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Sample records for acid-modified silica nanoparticles

  1. Hyaluronic acid modified mesoporous silica nanoparticles for targeted drug delivery to CD44-overexpressing cancer cells

    NASA Astrophysics Data System (ADS)

    Yu, Meihua; Jambhrunkar, Siddharth; Thorn, Peter; Chen, Jiezhong; Gu, Wenyi; Yu, Chengzhong

    2012-12-01

    In this paper, a targeted drug delivery system has been developed based on hyaluronic acid (HA) modified mesoporous silica nanoparticles (MSNs). HA-MSNs possess a specific affinity to CD44 over-expressed on the surface of a specific cancer cell line, HCT-116 (human colon cancer cells). The cellular uptake performance of fluorescently labelled MSNs with and without HA modification has been evaluated by confocal microscopy and fluorescence-activated cell sorter (FACS) analysis. Compared to bare MSNs, HA-MSNs exhibit a higher cellular uptake via HA receptor mediated endocytosis. An anticancer drug, doxorubicin hydrochloride (Dox), has been loaded into MSNs and HA-MSNs as drug delivery vehicles. Dox loaded HA-MSNs show greater cytotoxicity to HCT-116 cells than free Dox and Dox-MSNs due to the enhanced cell internalization behavior of HA-MSNs. It is expected that HA-MSNs have a great potential in targeted delivery of anticancer drugs to CD44 over-expressing tumors.

  2. Dual Mode Fluorophore-Doped Nickel Nitrilotriacetic Acid-Modified Silica Nanoparticles Combine Histidine-Tagged Protein Purification with Site-Specific Fluorophore Labeling

    PubMed Central

    Kim, Sung Hoon; Jeyakumar, M.; Katzenellenbogen, John A.

    2008-01-01

    We present the first example of a fluorophore-doped nickel chelate surface- modified silica nanoparticle that functions in a dual mode, combining histidine-tagged protein purification with site-specific fluorophore labeling. Tetramethylrhodamine (TMR)-doped silica nanoparticles, estimated to contain 700–900 TMRs per ca. 23-nm particle, were surface modified with nitrilotriacetic acid (NTA), producing TMR-SiO2-NTA-Ni+2. Silica-embedded TMR retains very high quantum yield, is resistant to quenching by buffer components and is modestly quenched and only to a certain depth (ca. 2 nm) by surface-attached Ni+2. When exposed to a bacterial lysate containing estrogen receptor α ligand binding domain (ERα) as a minor component, these beads showed very high specificity binding, enabling protein purification in one step. The capacity and specificity of these beads for binding a his-tagged protein were characterized by electrophoresis, radiometric counting, and MALDI-TOF MS. ERα, bound to TMR-SiO2-NTA-Ni++ beads in a site-specific manner, exhibited good activity for ligand binding and for ligand-induced binding to coactivators in solution FRET experiments and protein microarray fluorometric and FRET assays. This dual-mode type TMR-SiO2-NTA-Ni++ system represents a powerful combination of one-step histidine-tagged protein purification and site-specific labeling with multiple fluorophore species. BRIEFS Tetramethylrhodamine-doped silica nanoparticles surface modified with nitrilotriacetic acid are dual-mode agents that can be used to purify and site-specifically fluorophore label his-tagged proteins in one step for fluorometric and FRET experiments. PMID:17910454

  3. Tannic acid modified silver nanoparticles show antiviral activity in herpes simplex virus type 2 infection.

    PubMed

    Orlowski, Piotr; Tomaszewska, Emilia; Gniadek, Marianna; Baska, Piotr; Nowakowska, Julita; Sokolowska, Justyna; Nowak, Zuzanna; Donten, Mikolaj; Celichowski, Grzegorz; Grobelny, Jaroslaw; Krzyzowska, Malgorzata

    2014-01-01

    The interaction between silver nanoparticles and herpesviruses is attracting great interest due to their antiviral activity and possibility to use as microbicides for oral and anogenital herpes. In this work, we demonstrate that tannic acid modified silver nanoparticles sized 13 nm, 33 nm and 46 nm are capable of reducing HSV-2 infectivity both in vitro and in vivo. The antiviral activity of tannic acid modified silver nanoparticles was size-related, required direct interaction and blocked virus attachment, penetration and further spread. All tested tannic acid modified silver nanoparticles reduced both infection and inflammatory reaction in the mouse model of HSV-2 infection when used at infection or for a post-infection treatment. Smaller-sized nanoparticles induced production of cytokines and chemokines important for anti-viral response. The corresponding control buffers with tannic acid showed inferior antiviral effects in vitro and were ineffective in blocking in vivo infection. Our results show that tannic acid modified silver nanoparticles are good candidates for microbicides used in treatment of herpesvirus infections. PMID:25117537

  4. Diglycolamic acid modified silica gel for the separation of hazardous trivalent metal ions from aqueous solution.

    PubMed

    Suneesh, A S; Syamala, K V; Venkatesan, K A; Antony, M P; Vasudeva Rao, P R

    2015-01-15

    The surface of the silica gel was modified with diglycolamic acid moieties and the product (Si-DGAH) was characterized by elemental analysis, TG-DTA, (1)H and (29)Si NMR and scanning electron microscopy (SEM). The adsorption behavior of hazardous americium (III) and europium (III) in Si-DGAH was studied from aqueous nitric acid medium to examine the feasibility using the modified silica for the separation of Am(III) and Eu(III) from aqueous wastes. In this context, the effect of various parameters such as the duration of equilibration, and concentrations of europium, nitric acid, sodium nitrate and diethylenetriaminepentaacetic acid (DTPA) in aqueous phase, on the distribution coefficient (K(d)) of Am(III) and Eu(III) was investigated. The distribution coefficient of ∼10(3) mL/g (>99.9% extraction) was obtained for both Am(III) and Eu(III) at pH 3, and the K(d) values decreased with increase in the concentration of nitric acid. Rapid kinetics of extraction in the initial stages of equilibration, followed by the establishment of equilibrium occurred within 30 min. The extraction data were fitted into Langmuir adsorption model and the apparent europium extraction capacity was determined. Europium loading capacity of the sorbent was determined at various feed pH by column method. The study indicated the possibility of using diglycolamic acid-modified silica for the separation of Eu(III) and Am(III) from aqueous wastes. PMID:25454425

  5. Toxicity of tannic acid-modified silver nanoparticles in keratinocytes: potential for immunomodulatory applications.

    PubMed

    Orlowski, Piotr; Soliwoda, Katarzyna; Tomaszewska, Emilia; Bien, Karolina; Fruba, Aleksandra; Gniadek, Marianna; Labedz, Olga; Nowak, Zuzanna; Celichowski, Grzegorz; Grobelny, Jarosław; Krzyzowska, Malgorzata

    2016-09-01

    Hydrolyzable tannins are known to exhibit anti-inflammatory activity, which can be used in combination with silver nanoparticles (AgNPs) for dermal uses. In this study, we investigated the effects of tannic acid-modified 13, 33, 46nm and unmodified 10-65nm AgNPs using the human-derived keratinocyte HaCaT and VK2-E6/E7 cell lines in the form of stationary and spheroids cultures. After exposition to tannic acid-modified AgNPs, VK2-E6/E7 cells showed higher toxicity, increased production of reactive oxygen species (ROS) and activity of JNK stress kinase, while HaCaT cell line demonstrated less ROS production and activation of ERK kinase. AgNPs internalization was detected both in the superficial and internal layers of spheroids prepared from both cell lines. Tannic acid modified AgNPs sized above 30nm did not induce DNA breaks in comet assay performed in both cell lines. Tannic acid-modified but not unmodified AgNPs down-regulated TNF-α and LPS-triggered production of IL-8 in VK2-E6/E7 but not in HaCaT cells. In summary, tannic acid-modified AgNPs sized above 30nm show good toxicological profile both in vitro and possess immunomodulatory properties useful for potential dermal applications in humans. PMID:27216470

  6. Investigation of follicular and non-follicular pathways for polyarginine and oleic acid modified nanoparticles

    PubMed Central

    Hayden, Patrick; Singh, Mandip

    2013-01-01

    Purpose The aim of the current study was to investigate the percutaneous permeation pathways of cell penetrating peptide modified lipid nanoparticles and oleic acid modified polymeric nanoparticles. Methods Confocal microscopy was performed on skin cultures (EpiDermFT™) for modified and un-modified nanoparticles. Differential stripping was performed following in vitro skin permeation of Ibuprofen (Ibu) encapsulated nanoparticles to estimate Ibu levels in different skin layers and receiver compartment. The hair follicles (HF) were blocked and in vitro skin permeation of nanoparticles was then compared with unblocked HF. The surface modified nanoparticles were investigated for response on allergic contact dermatitis (ACD). Results Surface modified nanoparticles showed a significant higher (p < 0.05) in fluorescence in EpiDermFT™ cultures compared to controls. The HF play less than 5% role in total nanoparticle permeation into the skin. The Ibu levels were significantly high (p<0.05) for surface modified nanoparticles compared to controls. The Ibu levels in skin and receiver compartment were not significantly different when HF were open or closed. Modified nanoparticles showed significant improvement in treatment of ACD compared to solution. Conclusions Our studies demonstrate that increased skin permeation of surface modified nanoparticles is not only dependent on a follicular pathway but also occur through non-follicular pathway(s). PMID:23187866

  7. Doxorubicin-loaded glycyrrhetinic acid modified recombinant human serum albumin nanoparticles for targeting liver tumor chemotherapy.

    PubMed

    Qi, Wen-Wen; Yu, Hai-Yan; Guo, Hui; Lou, Jun; Wang, Zhi-Ming; Liu, Peng; Sapin-Minet, Anne; Maincent, Philippe; Hong, Xue-Chuan; Hu, Xian-Ming; Xiao, Yu-Ling

    2015-03-01

    Due to overexpression of glycyrrhetinic acid (GA) receptor in liver cancer cells, glycyrrhetinic acid modified recombinant human serum albumin (rHSA) nanoparticles for targeting liver tumor cells may result in increased therapeutic efficacy and decreased adverse effects of cancer therapy. In this study, doxorubicin (DOX) loaded and glycyrrhetinic acid modified recombinant human serum albumin nanoparticles (DOX/GA-rHSA NPs) were prepared for targeting therapy for liver cancer. GA was covalently coupled to recombinant human serum albumin nanoparticles, which could efficiently deliver DOX into liver cancer cells. The resultant GA-rHSA NPs exhibited uniform spherical shape and high stability in plasma with fixed negative charge (∼-25 mV) and a size about 170 nm. DOX was loaded into GA-rHSA NPs with a maximal encapsulation efficiency of 75.8%. Moreover, the targeted NPs (DOX/GA-rHSA NPs) showed increased cytotoxic activity in liver tumor cells compared to the nontargeted NPs (DOX/rHSA NPs, DOX loaded recombinant human serum albumin nanoparticles without GA conjugating). The targeted NPs exhibited higher cellular uptake in a GA receptor-positive liver cancer cell line than nontargeted NPs as measured by both flow cytometry and confocal laser scanning microscopy. Biodistribution experiments showed that DOX/GA-rHSA NPs exhibited a much higher level of tumor accumulation than nontargeted NPs at 1 h after injection in hepatoma-bearing Balb/c mice. Therefore, the DOX/GA-rHSA NPs could be considered as an efficient nanoplatform for targeting drug delivery system for liver cancer. PMID:25584860

  8. Binding of actin to thioglycolic acid modified superparamagnetic nanoparticles for antibody conjugation.

    PubMed

    Maltas, Esra; Ertekin, Betul

    2015-01-01

    Thioglycolic acid modified superparamagnetic iron oxide nanoparticles (TG-APTS-SPION) were synthesized by using (3-aminopropyl) triethoxysilane (APTS) and thioglycolic acid (TG). Actin was immobilized on the nanoparticle surfaces. Binding amount of the actin (Act) on TG-APTS-SPIONs was determined by using a calibration curve equation that was drawn using fluorescence spectra at 280 and 342 nm of excitation and emission wavelengths. Anti-Actin (anti-Act) was interacted with the actin immobilized TG-APTS-SPIONs as primary antibody. Horse radish peroxidase (HRP) was also interacted with antibody conjugated nanoparticles as secondary antibody. The binding capacity of primary and secondary antibodies was also estimated by fluorescence spectroscopy. Scanning electron microscopy (SEM), Infrared spectroscopy (FTIR) and energy dispersive X-ray (EDX) analysis were also clarified binding of the protein and antibodies to the nanoparticles' surfaces. Western blot analysis was also done for actin conjunction with anti Act antibody to confirm binding of the antibody to the protein. PMID:25451750

  9. Colorimetric Detection of Cadmium Ions Using DL-Mercaptosuccinic Acid-Modified Gold Nanoparticles.

    PubMed

    Chen, Na; Chen, Jun; Yang, Jing-Hua; Bai, Lian-Yang; Zhang, Yu-Ping

    2016-01-01

    A colorimetric assay has been developed for detection of Cd²⁺ utilizing DL-mercaptosuccinic acid-modified gold nanoparticles (MSA-AuNPs). The method showed good selectivity for Cd²⁺ over other metal ions. As a result, the linear relationships (r > 0.9606) between concentration 0.07 mM and 0.20 mM for cadmium ion were obtained. The detection limit was as low as 0.07 mM by the naked eye. The effect of pH on the aggregation was optimized. The MSA-AuNPs probe could be used to detect Cd²⁺ in an aqueous solution based on the aggregation-induced color change of MSA-AuNPs. PMID:27398533

  10. Poly(L-lactic acid)-modified silica stationary phase for reversed-phase and hydrophilic interaction liquid chromatography.

    PubMed

    Ohyama, Kaname; Takasago, Shizuka; Kishikawa, Naoya; Kuroda, Naotaka

    2015-03-01

    Poly(L-lactic acid) is a linear aliphatic thermoplastic polyester that can be produced from renewable resources. A poly(L-lactic acid)-modified silica stationary phase was newly prepared by amide bond reaction between amino groups on aminopropyl silica and carboxylic acid groups at the end of the poly(L-lactic acid) chain. The poly(L-lactic acid)-silica column was characterized in reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography with the use of different mobile phase compositions. The poly(L-lactic acid)-silica column was found to work in both modes, and the retention of test compounds depending on acetonitrile content exhibited "U-shaped" curves, which was an indicator of reversed-phase liquid chromatography/hydrophilic interaction liquid chromatography mixed-mode retention behavior. In addition, carbonyl groups included into the poly(L-lactic acid) backbone work as an electron-accepting group toward a polycyclic aromatic hydrocarbon and provide π-π interactions. PMID:25546473

  11. Hyaluronic Acid Modified Hollow Prussian Blue Nanoparticles Loading 10-hydroxycamptothecin for Targeting Thermochemotherapy of Cancer

    PubMed Central

    Jing, Lijia; shao, shangmin; Wang, Yang; Yang, Yongbo; Yue, Xiuli; Dai, Zhifei

    2016-01-01

    This paper reported the fabrication of a multifunctional nanoplatform by modifying hollow Prussian blue nanoparticles with hyaluronic acid grafting polyethylene glycol, followed by loading 10-hydroxycamptothecin for tumor-targeted thermochemotherapy. It was found that the surface modification of hollow Prussian blue nanoparticles with hyaluronic acid grafting polyethylene endowed a great colloidal stability, long blood circulation time and the capability for targeting Hela cells over-expressing the CD44 receptor. The obtained nanoagent exhibited efficient photothermal effect and a light triggered and stepwise release behavior of 10-hydroxycamptothecin due to the strong optical absorption in the near-infrared region. The investigations on the body weight change, histological injury and blood biochemical indexes showed that such nanoagent had excellent biocompatibility for medical application. Both in vitro and in vivo experiments proved that the combination of chemotherapy and photothermal therapy through the agent of hyaluronic acid modified Prussian blue nanoparticles loading 10-hydroxycamptothecin could significantly improve the therapeutic efficacy compared with either therapy alone because of a good synergetic effect. PMID:26722372

  12. Optimized synthesis of glycyrrhetinic acid-modified chitosan 5-fluorouracil nanoparticles and their characteristics

    PubMed Central

    Cheng, Mingrong; Chen, Houxiang; Wang, Yong; Xu, Hongzhi; He, Bing; Han, Jiang; Zhang, Zhiping

    2014-01-01

    The nanoparticle drug delivery system, which uses natural or synthetic polymeric material as a carrier to deliver drugs to targeted tissues, has a broad prospect for clinical application for its targeting, slow-release, and biodegradable properties. Here, we used chitosan (CTS) and hepatoma cell-specific binding molecule glycyrrhetinic acid to synthesize glycyrrhetinic acid-modified chitosan (GA-CTS). The synthetic product was confirmed by infrared (IR) spectra and hydrogen-1 nuclear magnetic resonance. The GA-CTS/5-fluorouracil (5-FU) nanoparticles were synthesized by combining GA-CTS and 5-FU and conjugating 5-FU onto the GA-CTS nanomaterial. The central composite design was performed to optimize the preparation process as CTS:tripolyphosphate sodium (TPP) weight ratio =5:1, 5-FU:CTS weight ratio =1:1, TPP concentration =0.05% (w/v), and cross-link time =50 minutes. GA-CTS/5-FU nanoparticles had a mean particle size of 193.7 nm, a polydispersity index of 0.003, a zeta potential of +27.4 mV, and a drug loading of 1.56%. The GA-CTS/5-FU nanoparticle had a protective effect on the drug against plasma degrading enzyme, and provided a sustained release system comprising three distinct phases of quick, steady, and slow release. Our study showed that the peak time, half-life time, mean residence time and area under the curve of GA-CTS/5-FU were longer or more than those of the 5-FU group, but the maximum concentration (Cmax) was lower. We demonstrated that the nanoparticles accumulated in the liver and have significantly inhibited tumor growth in an orthotropic liver cancer mouse model. PMID:24493926

  13. Synthesis of poly acrylic acid modified silver nanoparticles and their antimicrobial activities.

    PubMed

    Ni, Zhihui; Wang, Zhihua; Sun, Lei; Li, Binjie; Zhao, Yanbao

    2014-08-01

    Poly acrylic acid modified silver (Ag/PAA) nanoparticles (NPs) have been successfully synthesized in the aqueous solution by using tannic acid as a reductant. The structure, morphology and composition of Ag/PAA NPs were characterized by various techniques such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible absorption spectroscopy (UV-vis) and thermogravimetry analysis (TGA). The results show that PAA/Ag NPs have a quasi-ball shape with an average diameter of 10 nm and exhibit well crystalline, and the reaction conditions have some effect on products morphology and size distribution. In addition, the as-synthesized Ag/PAA NPs antimicrobial activities against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) were evaluated by the methods of broth dilution, cup diffusion, optical density (OD600) and electron microscopy observation. The as-synthesized Ag/PAA NPs exhibit excellent antibacterial activity. The antimicrobial mechanism may be attributed to the damaging of bacterial cell membrane and causing leakage of cytoplasm. PMID:24907758

  14. Phenylboronic acid modified silver nanoparticles for colorimetric dynamic analysis of glucose.

    PubMed

    Cao, Ke; Jiang, Xiaomei; Yan, Suting; Zhang, Laiying; Wu, Weitai

    2014-02-15

    The development of advanced nanostructures that allow dynamic quantification of glucose level can contribute to tight glucose control in diabetes management and other medical/biological fields. In this paper, we demonstrated that the assemblies of the 5-amino-2-fluorophenylboronic acid modified silver nanoparticles (FPBA-AgNPs) can be employed for highly modulating, sensitive, and selective colorimetric sensing of glucose over a physiologically important concentration range of 0-20mM at a physiological pH of 7.4. The glucose-modulated assembly of the FPBA-AgNPs occurred by the regulable formation of interparticle linkages via the bridged binding of 1,2-cis-diols and 5,6-cis-diols (for furanose form; or 4,6-cis-diols for pyranose form), respectively, of a glucose molecule to two FPBA-AgNPs. The detection limit was 89.0 μM. The mean error of glucose detection in a macro-bio-system, blood serum of adult, was smaller than 10%. Furthermore, we show that the glucose level variations associated with a model biological reaction process can be monitored by using the FPBA-AgNPs, whilst with the reaction mechanism remaining nearly unchanged. PMID:24055932

  15. Effect of oleic acid modified polymeric bilayered nanoparticles on percutaneous delivery of spantide II and ketoprofen

    PubMed Central

    Shah, Punit; Desai, Pinaki; Singh, Mandip

    2011-01-01

    The objective of present study was to evaluate the effect of oleic acid modified polymeric bilayered nanoparticles (NPS) on combined delivery of two anti-inflammatory drugs, spantide II (SP) and ketoprofen (KP) on the skin permeation. NPS were prepared using poly(lactic-co-glycolic acid) (PLGA) and chitosan. SP and KP were encapsulated in different layers alone or/and in combination (KP-NPS, SP-NPS and SP+KP-NPS). The surface of NPS was modified with oleic acid (OA) (`Nanoease' technology) using an established procedure in the laboratory (KP-NPS-OA, SP-NPS-OA and SP+KP-NPS-OA). Fluorescent dyes (DiO and DID) containing surface modified (DiO-NPS-OA and DID-NPS-OA) and unmodified NPS (DiO-NPS and DID-NPS) were visualized in lateral rat skin sections using confocal microscopy and Raman confocal spectroscopy after skin permeation. In vitro skin permeation was performed in dermatomed human skin and HPLC was used to analyze the drug levels in different skin layers. Further, allergic contact dermatitis (ACD) model was used to evaluate the response of KP-NPS, SP-NPS, SP+KP-NPS, KP-NPS-OA, SP-NPS-OA and SP+KP-NPS-OA treatment in C57BL/6 mice. The fluorescence from OA modified NPS was observed upto depth of 240 μm and was significantly higher as compared to non-modified NPS. The amount of SP and KP retained in skin layers from OA modified NPS increased by several folds compare to unmodified NPS and control solution. In addition, the combination index value calculated from ACD response for solution suggested additive effect and moderate synergism for NPS-OA. Our results strongly suggest that surface modification of bilayered nanoparticles with oleic acid improved drug delivery to the deeper skin layers. PMID:22134117

  16. Proton Conductivity of Nafion/Ex-Situ Sulfonic Acid-Modified Stöber Silica Nanocomposite Membranes As a Function of Temperature, Silica Particles Size and Surface Modification

    PubMed Central

    Muriithi, Beatrice; Loy, Douglas A.

    2016-01-01

    The introduction of sulfonic acid modified silica in Nafion nanocomposite membranes is a good method of improving the Nafion performance at high temperature and low relative humidity. Sulfonic acid-modified silica is bifunctional, with silica phase expected to offer an improvement in membranes hydration while sulfonic groups enhance proton conductivity. However, as discussed in this paper, this may not always be the case. Proton conductivity enhancement of Nafion nanocomposite membranes is very dependent on silica particle size, sometimes depending on experimental conditions, and by surface modification. In this study, Sulfonated Preconcentrated Nafion Stober Silica composites (SPNSS) were prepared by modification of Stober silica particles with mercaptopropyltriethoxysilane, dispersing the particles into a preconcentrated solution of Nafion, then casting the membranes. The mercapto groups were oxidized to sulfonic acids by heating the membranes in 10 wt % hydrogen peroxide for 1 h. At 80 °C and 100% relative humidity, a 20%–30% enhancement of proton conductivity was only observed when sulfonic acid modified particle less than 50 nm in diameter were used. At 120 °C, and 100% humidity, proton conductivity increased by 22%–42% with sulfonated particles with small particles showing the greatest enhancement. At 120 °C and 50% humidity, the sulfonated particles are less efficient at keeping the membranes hydrated, and the composites underperform Nafion and silica-Nafion nanocomposite membranes. PMID:26828525

  17. Proton Conductivity of Nafion/Ex-Situ Sulfonic Acid-Modified Stöber Silica Nanocomposite Membranes As a Function of Temperature, Silica Particles Size and Surface Modification.

    PubMed

    Muriithi, Beatrice; Loy, Douglas A

    2016-01-01

    The introduction of sulfonic acid modified silica in Nafion nanocomposite membranes is a good method of improving the Nafion performance at high temperature and low relative humidity. Sulfonic acid-modified silica is bifunctional, with silica phase expected to offer an improvement in membranes hydration while sulfonic groups enhance proton conductivity. However, as discussed in this paper, this may not always be the case. Proton conductivity enhancement of Nafion nanocomposite membranes is very dependent on silica particle size, sometimes depending on experimental conditions, and by surface modification. In this study, Sulfonated Preconcentrated Nafion Stober Silica composites (SPNSS) were prepared by modification of Stober silica particles with mercaptopropyltriethoxysilane, dispersing the particles into a preconcentrated solution of Nafion, then casting the membranes. The mercapto groups were oxidized to sulfonic acids by heating the membranes in 10 wt % hydrogen peroxide for 1 h. At 80 °C and 100% relative humidity, a 20%-30% enhancement of proton conductivity was only observed when sulfonic acid modified particle less than 50 nm in diameter were used. At 120 °C, and 100% humidity, proton conductivity increased by 22%-42% with sulfonated particles with small particles showing the greatest enhancement. At 120 °C and 50% humidity, the sulfonated particles are less efficient at keeping the membranes hydrated, and the composites underperform Nafion and silica-Nafion nanocomposite membranes. PMID:26828525

  18. Application of silica nanoparticles for increased silica availability in maize

    NASA Astrophysics Data System (ADS)

    Suriyaprabha, R.; Karunakaran, G.; Yuvakkumar, R.; Prabu, P.; Rajendran, V.; Kannan, N.

    2013-02-01

    Silica nanoparticles were extracted from rice husk and characterised comprehensively. The synthesised silica powders were amorphous in size with 99.7% purity (20-40 nm). Nanosilica was amended with red soil at 15 kg ha-1 along with micron silica. The influence of nanoscale on silica uptake, accumulation and nutritional variations in maize roots were evaluated through the studies such as root sectioning, elemental analysis and physiological parameters (root length and silica content) and compared with micron silica and control. Nanosilica treated soil reveals enhanced silica uptake and elongated roots which make the plant to resist in stress conditions like drought.

  19. Surface modification of silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Ranjan, Rajesh

    Surface modification of nanosized silica particles by polymer grafting is gaining attention. This can be attributed to the fact that it provides a unique opportunity to engineer the interfacial properties of these modified particles; at the same time the mechanical and thermal properties of the polymers can be improved. Controlled free radical polymerization is a versatile technique which affords control over molecular weight, molecular weight distribution, architecture and functionalities of the resulting polymer. Three commonly used controlled free radical polymerizations include nitroxide-mediated polymerization (NMP), atom transfer radical polymerization (ATRP) and reversible addition fragmentation transfer (RAFT) polymerization. ATRP and RAFT polymerization were explored in order to modify the silica surface with well-defined polymer brushes. A novel click-functionalized RAFT chain transfer agent (RAFT CTA) was synthesized which opened up the possibility of using RAFT polymerization and click chemistry together in surface modification. Using this RAFT CTA, the surface of silica nanoparticles was modified with polystyrene and polyacrylamide brushes via the "grafting to" approach. Both tethered polystyrene and polyacrylamide chains were found in the brush regime. The combination of ATRP and click chemistry was also explored for surface modification. A combination of RAFT polymerization and click chemistry was also studied to modify the surface via the "grafting from" approach. Our strategy included the (1) "grafting from" approach for brush formation (2) facile click reaction to immobilize the RAFT agent (3) synthesis of R-supported chain transfer agent and (4) use of the more active trithiocarbonate RAFT agent. Grafting density obtained by this method was significantly higher than reported values in the literature. Polystyrene (PS) grafted silica nanoparticles were also prepared by a tandem process that simultaneously employs reversible addition fragmentation

  20. Synthesis of mesoporous silica nanoparticles.

    PubMed

    Wu, Si-Han; Mou, Chung-Yuan; Lin, Hong-Ping

    2013-05-01

    Good control of the morphology, particle size, uniformity and dispersity of mesoporous silica nanoparticles (MSNs) is of increasing importance to their use in catalyst, adsorption, polymer filler, optical devices, bio-imaging, drug delivery, and biomedical applications. This review discusses different synthesis methodologies to prepare well-dispersed MSNs and hollow silica nanoparticles (HSNs) with tunable dimensions ranging from a few to hundreds of nanometers of different mesostructures. The methods include fast self-assembly, soft and hard templating, a modified Stöber method, dissolving-reconstruction and modified aerogel approaches. In practical applications, the MSNs prepared by these methods demonstrate good potential for use in high-performance catalysis, antireflection coating, transparent polymer-MSNs nanocomposites, drug-release and theranostic systems. PMID:23403864

  1. Cellular membrane trafficking of mesoporous silica nanoparticles

    SciTech Connect

    Fang, I-Ju

    2012-01-01

    This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulf some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine

  2. Hyaluronic acid modified mesoporous carbon nanoparticles for targeted drug delivery to CD44-overexpressing cancer cells

    NASA Astrophysics Data System (ADS)

    Wan, Long; Jiao, Jian; Cui, Yu; Guo, Jingwen; Han, Ning; Di, Donghua; Chang, Di; Wang, Pu; Jiang, Tongying; Wang, Siling

    2016-04-01

    In this paper, hyaluronic acid (HA) functionalized uniform mesoporous carbon spheres (UMCS) were synthesized for targeted enzyme responsive drug delivery using a facile electrostatic attraction strategy. This HA modification ensured stable drug encapsulation in mesoporous carbon nanoparticles in an extracellular environment while increasing colloidal stability, biocompatibility, cell-targeting ability, and controlled cargo release. The cellular uptake experiments of fluorescently labeled mesoporous carbon nanoparticles, with or without HA functionalization, demonstrated that HA-UMCS are able to specifically target cancer cells overexpressing CD44 receptors. Moreover, the cargo loaded doxorubicin (DOX) and verapamil (VER) exhibited a dual pH and hyaluronidase-1 responsive release in the tumor microenvironment. In addition, VER/DOX/HA-UMCS exhibited a superior therapeutic effect on an in vivo HCT-116 tumor in BALB/c nude mice. In summary, it is expected that HA-UMCS will offer a new method for targeted co-delivery of drugs to tumors overexpressing CD44 receptors.

  3. Hyaluronic Acid Modified Tantalum Oxide Nanoparticles Conjugating Doxorubicin for Targeted Cancer Theranostics.

    PubMed

    Jin, Yushen; Ma, Xibo; Feng, Shanshan; Liang, Xiao; Dai, Zhifei; Tian, Jie; Yue, Xiuli

    2015-12-16

    Theranostic tantalum oxide nanoparticles (TaOxNPs) of about 40 nm were successfully developed by conjugating functional molecules including polyethylene glycol (PEG), near-infrared (NIR) fluorescent dye, doxorubicin (DOX), and hyaluronic acid (HA) onto the surface of the nanoparticles (TaOx@Cy7-DOX-PEG-HA NPs) for actively targeting delivery, pH-responsive drug release, and NIR fluorescence/X-ray CT bimodal imaging. The obtained nanoagent exhibits good biocompatibility, high cumulative release rate in the acidic microenvironments, long blood circulation time, and superior tumor-targeting ability. Both in vitro and in vivo experiments show that it can serve as an excellent contrast agent to simultaneously enhance fluorescence imaging and CT imaging greatly. Most importantly, such a nanoagent could enhance the therapeutic efficacy of the tumor greatly and the tumor growth inhibition was evaluated to be 87.5%. In a word, multifunctional TaOx@Cy7-DOX-PEG-HA NPs can serve as a theranostic nanomedicine for fluorescence/X-ray CT bimodal imaging, remote-controlled therapeutics, enabling personalized detection, and treatment of cancer with high efficacy. PMID:26554699

  4. Pathway of cytotoxicity induced by folic acid modified selenium nanoparticles in MCF-7 cells.

    PubMed

    Pi, Jiang; Jin, Hua; Liu, Ruiying; Song, Bing; Wu, Qing; Liu, Li; Jiang, Jinhuan; Yang, Fen; Cai, Huaihong; Cai, Jiye

    2013-02-01

    Selenium nanoparticles (Se NPs) have been recognized as promising materials for biomedical applications. To prepare Se NPs which contained cancer targeting methods and to clarify the cellular localization and cytotoxicity mechanisms of these Se NPs against cancer cells, folic acid protected/modified selenium nanoparticles (FA-Se NPs) were first prepared by a one-step method. Some morphologic and spectroscopic methods were obtained to prove the successfully formation of FA-Se NPs while free folate competitive inhibition assay, microscope, and several biological methods were used to determine the in vitro uptake, subcellular localization, and cytotoxicity mechanism of FA-Se NPs in MCF-7 cells. The results indicated that the 70-nm FA-Se NPs were internalized by MCF-7 cells through folate receptor-mediated endocytosis and targeted to mitochondria located regions through endocytic vesicles transporting. Then, the FA-Se NPs entered into mitochondria; triggered the mitochondria-dependent apoptosis of MCF-7 cells which involved oxidative stress, Ca(2)+ stress changes, and mitochondrial dysfunction; and finally caused the damage of mitochondria. FA-Se NPs released from broken mitochondria were transported into nucleus and further into nucleolus which then induced MCF-7 cell cycle arrest. In addition, FA-Se NPs could induce cytoskeleton disorganization and induce MCF-7 cell membrane morphology alterations. These results collectively suggested that FA-Se NPs could be served as potential therapeutic agents and organelle-targeted drug carriers in cancer therapy. PMID:22945264

  5. Hyaluronic acid modified mesoporous carbon nanoparticles for targeted drug delivery to CD44-overexpressing cancer cells.

    PubMed

    Wan, Long; Jiao, Jian; Cui, Yu; Guo, Jingwen; Han, Ning; Di, Donghua; Chang, Di; Wang, Pu; Jiang, Tongying; Wang, Siling

    2016-04-01

    In this paper, hyaluronic acid (HA) functionalized uniform mesoporous carbon spheres (UMCS) were synthesized for targeted enzyme responsive drug delivery using a facile electrostatic attraction strategy. This HA modification ensured stable drug encapsulation in mesoporous carbon nanoparticles in an extracellular environment while increasing colloidal stability, biocompatibility, cell-targeting ability, and controlled cargo release. The cellular uptake experiments of fluorescently labeled mesoporous carbon nanoparticles, with or without HA functionalization, demonstrated that HA-UMCS are able to specifically target cancer cells overexpressing CD44 receptors. Moreover, the cargo loaded doxorubicin (DOX) and verapamil (VER) exhibited a dual pH and hyaluronidase-1 responsive release in the tumor microenvironment. In addition, VER/DOX/HA-UMCS exhibited a superior therapeutic effect on an in vivo HCT-116 tumor in BALB/c nude mice. In summary, it is expected that HA-UMCS will offer a new method for targeted co-delivery of drugs to tumors overexpressing CD44 receptors. PMID:26901756

  6. Polyacrylic acid modified upconversion nanoparticles for simultaneous pH-triggered drug delivery and release imaging.

    PubMed

    Jia, Xuekun; Yin, Jinjin; He, Dinggeng; He, Xiaoxiao; Wang, Kemin; Chen, Mian; Li, Yuhong

    2013-12-01

    A poly(acrylicacid)-modified NaYF4:Yb, Er upconversion nanoparticles (PAA-UCNPs) with dual functions of drug delivery and release imaging have been successfully developed. The PAA polymer coated on the surface of UCNPs serve as a pH-sensitive nanovalve for loading drug molecules via electrostatic interaction. The drug-loading efficiency of the PAA-UCNPs was investigated by using doxorubicin hydrochloride (DOX) as a model anticancer drug to evaluate their potential as a delivery system. Results showed loading and releasing of DOX from PAA-UCNPs were controlled by varying pH, with high encapsulation rate at weak alkaline conditions and an increased drug dissociation rate in acidic environment, which is favorable for construct a pH-responsive controlled drug delivery system. The in vitro cytotoxicity test using HeLa cell line indicated that the DOX loaded PAA-UCNPs (DOX@PAA-UCNPs) were distinctly cytotoxic to HeLa cells, while the PAA-UCNPs were highly biocompatible and suitable to use as drug carriers. Furthermore, the upconversion fluorescence resonance energy transfer (UFRET) imaging through the two-photon laser scanning microscopy (TLSM) revealed the time course of intracellular delivery of DOX from DOX@PAA-UCNPs. Thus, PAA-UCNPs are effective for constructing pH-responsive controlled drug delivery systems for multi-functional cancer therapy and imaging. PMID:24266261

  7. Fabrication and characterization of citric acid-modified starch nanoparticles/plasticized-starch composites.

    PubMed

    Ma, Xiaofei; Jian, Ruijuan; Chang, Peter R; Yu, Jiugao

    2008-11-01

    Starch nanoparticles (SN) were prepared by delivering ethanol as the precipitant into starch-paste solution dropwise. Citric acid (CA) modified SN (CASN) were fabricated with the dry preparation technique. According to the characterization of CASN with Fourier transform infrared, X-ray diffraction, rapid visco analyzer, and scanning electron microscopy (SEM), amorphous CASN could not be gelatinized in hot water because of the cross-linking, and most of CASN ranged in size from about 50 to 100 nm. The nanocomposites were also prepared using CASN as the filler in glycerol plasticized-pea starch (GPS) matrix by the casting process. SEM revealed that CASN was dispersed evenly in the GPS matrix. As shown in dynamic mechanical thermal analysis, the introduction of CASN could improve the storage modulus and the glass transition temperature of CASN/GPS composites. The tensile yield strength and Young's modulus increased from 3.94 to 8.12 MPa and from 49.8 to 125.1 MPa, respectively, when the CASN contents varied from 0 to 4 wt %. Moreover, the values of water vapor permeability decreased from 4.76 x 10(-10) to 2.72 x 10(-10) g m(-1) s(-1) Pa(-1). The improvement of these properties could be attributed to the good interaction between CASN filler and GPS matrix. The comprehensive application of green chemistry principles were demonstrated in the preparation of CASN and CASN/GPS composites. PMID:18844405

  8. Characterization and immobilization of trypsin on tannic acid modified Fe3O4 nanoparticles.

    PubMed

    Atacan, Keziban; Özacar, Mahmut

    2015-04-01

    Fe3O4 nanoparticles (NPs) were synthesized by co-precipitating Fe2+ and Fe3+ in an ammonia solution. Fe3O4 NPs functionalized with tannic acid were prepared. After functionalization process, trypsin enzyme was immobilized on these Fe3O4 NPs. The influence of pH, temperature, thermal stability, storage time stability and reusability on non-covalent immobilization was studied. The properties of Fe3O4 and its modified forms were examined by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), UV-vis spectrometer (UV) and X-ray diffraction (XRD), magnetization and zeta potential measurements. The immobilized enzyme was slightly more stable than the free enzyme at 45°C. According to the results, the activity of immobilized trypsin was preserved 55% at 45°C after 2 h and 90% after 120 days storage. In addition, the activity of the immobilized trypsin was preserved 40% of its initial activity after eight times of successive reuse. PMID:25686792

  9. Cadmium removal from water using thiolactic acid-modified titanium dioxide nanoparticles.

    SciTech Connect

    Skubal, L. R.; Meshkov, N. K.; Rajh, T.; Thurnauer, M.

    2002-05-31

    This study investigated the use of titanium dioxide (TiO{sub 2}) nanoparticles to remove aqueous cadmium from simulated wastewaters. Nanosized (45 A) colloids of anatase TiO{sub 2} were synthesized through the controlled hydrolysis of TiCl4 and their surfaces modified with the bidental chelating agent thiolactic acid (TLA). Colloids were introduced into 65 ppm cadmium-laden waters, and the suspensions were purged aerobically, anoxically with an inert gas, or by a sequential aerobic/anoxic purge. Suspensions were illuminated with 253.7 nm light. In each experiment, samples were taken from the reactor, filtered, and the filtrates analyzed by atomic absorption spectroscopy for residual cadmium. Results from the aerobic experiments exhibited minimal (approximately 10%) removal of the cadmium from solution and no reduction of the metal on either the modified or the unmodified colloid. Anoxic results were more promising, showing no cadmium reduction on the unmodified colloid but a 40% adsorption and reduction (from a +2 valence state to elemental cadmium as determined by methyl viologen tests) of cadmium on TLA-modified colloid in the presence of light. Results from the mixed atmospheric conditions fared the best and demonstrated that in the absence of light, approximately 20% of aqueous cadmium was sorbed to the modified colloid via a Freundlich adsorption isotherm. Upon illumination, greater than 90% of cadmium was removed by both adsorption and reduction processes onto the TLA-modified TiO{sub 2}. These removal and reduction processes were catalytic in nature. Results from this study are significant because to date, no other research in the literature has been able to accomplish cadmium removal and reduction using TiO{sub 2}.

  10. Encapsulation of silica nanoparticles by redox-initiated graft polymerization from the surface of silica nanoparticles.

    PubMed

    Wang, Huijun; Peng, Mao; Zheng, Jun; Li, Peng

    2008-10-01

    This study describes a facile and versatile method for preparing polymer-encapsulated silica particles by 'grafting from' polymerization initiated by a redox system comprising ceric ion (Ce(4+)) as an oxidant and an organic reductant immobilized on the surface of silica nanoparticles. The silica nanoparticles were firstly modified by 3-aminopropyltriethoxysilane, then reacted with poly(ethylene glycol) acrylate through the Michael addition reaction, so that hydroxyl-terminated poly(ethylene glycol) (PEG) were covalently attached onto the nanoparticle surface and worked as the reductant. Poly(methyl methacrylate) (PMMA), a common hydrophobic polymer, and poly(N-isopropylacrylamide) (PNIPAAm), a thermosensitive polymer, were successfully grafted onto the surface of silica nanoparticles by 'grafting from' polymerization initiated by the redox reaction of Ce(4+) with PEG on the silica surface in acid aqueous solutions. The polymer-encapsulated silica nanoparticles (referred to as silica@PMMA and silica@PNIPAAm, respectively) were characterized by infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy. On the contrary, graft polymerization did not occur on bare silica nanoparticles. In addition, during polymerization, sediments were observed for PMMA and for PNIPAAm at a polymerization temperature above its low critical solution temperature (LCST). But the silica@PNIPAAm particles obtained at a polymerization temperature below the LCST can suspend stably in water throughout the polymerization process. PMID:18684468

  11. Modeling of boldine alkaloid adsorption onto pure and propyl-sulfonic acid-modified mesoporous silicas. A comparative study.

    PubMed

    Geszke-Moritz, Małgorzata; Moritz, Michał

    2016-12-01

    The present study deals with the adsorption of boldine onto pure and propyl-sulfonic acid-functionalized SBA-15, SBA-16 and mesocellular foam (MCF) materials. Siliceous adsorbents were characterized by nitrogen sorption analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR) spectroscopy and thermogravimetric analysis. The equilibrium adsorption data were analyzed using the Langmuir, Freundlich, Redlich-Peterson, and Temkin isotherms. Moreover, the Dubinin-Radushkevich and Dubinin-Astakhov isotherm models based on the Polanyi adsorption potential were employed. The latter was calculated using two alternative formulas including solubility-normalized (S-model) and empirical C-model. In order to find the best-fit isotherm, both linear regression and nonlinear fitting analysis were carried out. The Dubinin-Astakhov (S-model) isotherm revealed the best fit to the experimental points for adsorption of boldine onto pure mesoporous materials using both linear and nonlinear fitting analysis. Meanwhile, the process of boldine sorption onto modified silicas was described the best by the Langmuir and Temkin isotherms using linear regression and nonlinear fitting analysis, respectively. The values of adsorption energy (below 8kJ/mol) indicate the physical nature of boldine adsorption onto unmodified silicas whereas the ionic interactions seem to be the main force of alkaloid adsorption onto functionalized sorbents (energy of adsorption above 8kJ/mol). PMID:27612776

  12. Investigations into the separation behaviour of perfluorinated C8 and undecanoic acid modified silica hydride stationary phases.

    PubMed

    Kulsing, Chadin; Yang, Yuanzhong; Sepehrifar, Roshanak; Lim, Michael; Toppete, Joshua; Matyska, Maria T; Pesek, Joseph J; Boysen, Reinhard I; Hearn, Milton T W

    2016-04-15

    In this study, the surface charge properties of perfluorinated C8 (PerfluoroC8) and undecanoic acid (UDA) modified silica hydride stationary phases have been investigated. The zeta potential values of these stationary phases were measured in aqueous/acetonitrile mobile phases of different pH, buffer concentrations and acetonitrile contents. The retention behaviour of several basic, acidic and neutral compounds were then examined with these two stationary phases, with U-shaped retention dependencies evident with regard to the organic solvent content of the mobile phase. Plots of the logarithmic retention factor versus buffer concentration revealed slopes ≥ -0.41 for both stationary phases, indicating the involvement of mixed mode retention mechanisms with contributions from both ionic and non-ionic interactions. Using a linear solvation energy relationship approach, the origins of these interactions under different mobile phase conditions were differentiated and quantified. The PerfluoroC8 stationary phase exhibited stronger retention for basic compounds under high acetonitrile content mobile phase conditions, whilst stronger retention was observed for all compounds with the UDA stationary phase under high aqueous content mobile phase conditions. The more negative zeta potentials of the UDA stationary phase correlated with higher total charge density, surface charge density and charge density at the beta plane (the outer plane of the double layer) compared to the PerfluoroC8 stationary phase. With mobile phases of low buffer concentrations, more negative zeta potential values were unexpectedly observed for the PerfluoroC8 stationary phase with slight increases in the C descriptor value, reflecting also the greater accessibility of the analytes to the stationary phase surface. Comparison of the retention behaviours on these phases with other types of silica hydride stationary phases has revealed different patterns of selectivity. PMID:27016444

  13. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Siloxane modified silica nanoparticles... Specific Chemical Substances § 721.10119 Siloxane modified silica nanoparticles (generic). (a) Chemical... as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this...

  14. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Siloxane modified silica nanoparticles... Specific Chemical Substances § 721.10119 Siloxane modified silica nanoparticles (generic). (a) Chemical... as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this...

  15. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Siloxane modified silica nanoparticles... Specific Chemical Substances § 721.10119 Siloxane modified silica nanoparticles (generic). (a) Chemical... as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this...

  16. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Siloxane modified silica nanoparticles... Specific Chemical Substances § 721.10119 Siloxane modified silica nanoparticles (generic). (a) Chemical... as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this...

  17. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Siloxane modified silica nanoparticles... Specific Chemical Substances § 721.10119 Siloxane modified silica nanoparticles (generic). (a) Chemical... as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this...

  18. Nonporous Silica Nanoparticles for Nanomedicine Application

    PubMed Central

    Tang, Li; Cheng, Jianjun

    2013-01-01

    Summary Nanomedicine, the use of nanotechnology for biomedical applications, has potential to change the landscape of the diagnosis and therapy of many diseases. In the past several decades, the advancement in nanotechnology and material science has resulted in a large number of organic and inorganic nanomedicine platforms. Silica nanoparticles (NPs), which exhibit many unique properties, offer a promising drug delivery platform to realize the potential of nanomedicine. Mesoporous silica NPs have been extensively reviewed previously. Here we review the current state of the development and application of nonporous silica NPs for drug delivery and molecular imaging. PMID:23997809

  19. Growth of hydroxyapatite nanoparticles on silica gels.

    PubMed

    Rivera-Muñoz, E M; Huirache-Acuña, R; Velázquez, R; Alonso-Núñez, G; Eguía-Eguía, S

    2011-06-01

    Synthetic, hydroxyapatite nanoparticles were grown on the surface of silica gels. The synthesis of those nanoparticles was obtained by immersing silica gels in a simulated body fluid (SBF) at 37 degrees C. The SBF was replaced every week to keep constant the Ca and P ion concentration and subsequent growth of hydroxyapatite was evaluated after 1-6 weeks of total soaking time in SBF. Hydroxyapatite nanoparticles were observed by scanning electron microscopy (SEM) on the surface of silica gel samples and confirmed by energy dispersive X-ray spectroscopy (EDS), Fourier Transform Infra Red Spectroscopy (FTIR) and powder X-ray Diffractometry (XRD) analysis. These particles show a regular shape and uniform size every week, keeping within the nanoscale always. Both the size and morphology of hydroxyapatite nanoparticles obtained are the result of the use of different chemical additives in the synthesis of silica gels, since they affect the liquid-to-solid interface, and the growth could correspond to a diffusion limited aggregation (DLA) process. A more detailed analysis, with higher magnifications, showed that hydroxyapatite nanoparticles are not solid spheres, showing a branched texture and their size depends on the scale and resolution of the measure instrument. PMID:21770224

  20. Bright photoluminescent hybrid mesostructured silica nanoparticles.

    PubMed

    Miletto, Ivana; Bottinelli, Emanuela; Caputo, Giuseppe; Coluccia, Salvatore; Gianotti, Enrica

    2012-07-28

    Bright photoluminescent mesostructured silica nanoparticles were synthesized by the incorporation of fluorescent cyanine dyes into the channels of MCM-41 mesoporous silica. Cyanine molecules were introduced into MCM-41 nanoparticles by physical adsorption and covalent grafting. Several photoluminescent nanoparticles with different organic loadings have been synthesized and characterized by X-ray powder diffraction, high resolution transmission electron microscopy and nitrogen physisorption porosimetry. A detailed photoluminescence study with the analysis of fluorescence lifetimes was carried out to elucidate the cyanine molecules distribution within the pores of MCM-41 nanoparticles and the influence of the encapsulation on the photoemission properties of the guests. The results show that highly stable photoluminescent hybrid materials with interesting potential applications as photoluminescent probes for diagnostics and imaging can be prepared by both methods. PMID:22706523

  1. Nanoparticle-assisted laser desorption/ionization using sinapic acid-modified iron oxide nanoparticles for mass spectrometry analysis.

    PubMed

    Komori, Hanaka; Hashizaki, Riho; Osaka, Issey; Hibi, Takao; Katano, Hajime; Taira, Shu

    2015-12-21

    Iron oxide-based nanoparticles (NP) were covalently modified with sinapic acid (SA) through a condensation reaction to assist the ionization of both large and small molecules. The morphology of SA-modified NPs (SA-NP) was characterized by transmission electron microscopy (TEM), and the modification of the NP surface with SA was confirmed using ultraviolet (UV) and infrared (IR) spectroscopy. The number of SA molecules was estimated to be 6 per NP. SA-NP-assisted laser desorption/ionization was carried out on small molecules, such as pesticides and plant hormones, and large molecules, such as peptides and proteins. A peptide fragment from degraded proteins was detected more efficiently compared with conventional methods. PMID:26535417

  2. Nanoparticle-doped radioluminescent silica optical fibers

    NASA Astrophysics Data System (ADS)

    Mrazek, J.; Nikl, M.; Kasik, I.; Podrazky, O.; Aubrecht, J.; Beitlerova, A.

    2014-05-01

    This contribution deals with the preparation and characterization of the silica optical fibers doped by nanocrystalline zinc silicate. The sol-gel approach was employed to prepare colloidal solution of zinc silicate precursors. Prepared sol was thermally treated to form nanocrystalline zinc silicate disperzed inside amorphous silica matrix or soaked inside the porous silica frit deposed inside the silica substrate tube which was collapsed into preform and drawn into optical fiber. Single mode optical fiber with the core diameter 15 μm and outer diamer 125 μm was prepared. Optical and waveguiding properties of the fiber were analyzed. Concentration of the zinc silicate in the fiber was 0.93 at. %. Radioluminescence properties of nanocrystalline zinc silicate powder and of the prepared optical fiber were investigated. The nanoparticle doped samples appear a emission maximum at 390 nm.

  3. Assembly of functional gold nanoparticle on silica microsphere.

    PubMed

    Wang, Hsuan-Lan; Lee, Fu-Cheng; Tang, Tse-Yu; Zhou, Chenguang; Tsai, De-Hao

    2016-05-01

    We demonstrate a controlled synthesis of silica microsphere with the surface-decorated functional gold nanoparticles. Surface of silica microsphere was modified by 3-aminopropypltriethoxysilane and 3-aminopropyldimethylethoxysilane to generate a positive electric field, by which the gold nanoparticles with the negative charges (unconjugated, thiolated polyethylene glycol functionalized with the traceable packing density and conformation) were able to be attracted to the silica microsphere. Results show that both the molecular conjugation on gold nanoparticle and the uniformity in the amino-silanization of silica microsphere influenced the loading and the homogeneity of gold nanoparticles on silica microsphere. The 3-aminopropyldimethylethoxysilane-functionalized silica microsphere provided an uniform field to attract gold nanoparticles. Increasing the ethanol content in aminosilane solution significantly improved the homogeneity and the loading of gold nanoparticles on the surface of silica microsphere. For the gold nanoparticle, increasing the molecular mass of polyethylene glycol yielded a greater homogeneity but a lower loading on silica microsphere. Bovine serum albumin induced the desorption of gold nanoparticles from silica microsphere, where the extent of desorption was suppressed by the presence of high-molecular mass polyethylene glycol on gold nanoparticles. This work provides the fundamental understanding for the synthesis of gold nanoparticle-silica microsphere constructs useful to the applications in chemo-radioactive therapeutics. PMID:26874272

  4. Electroactive Silica Nanoparticles for Biological Labeling

    SciTech Connect

    Wang, Jun; Liu, Guodong; Lin, Yuehe

    2006-08-29

    A novel electrochemical immuno-biosensor based on poly(guanine)-functionalized silica nanoparticle labels and mediator-generated catalytic reaction was described. The functionalized silica NPs conjugates were characterized by atomic force microscopy, X-ray photoelectron spectroscopy, and electrochemistry. This immunobiosensor is very sensitive and the limit of detection was found to be down to 0.2 ng/ml (4 pM), which was attributed to signal amplification by poly[G] functionalized silica NPs and guanine catalytic oxidation. Attractive feature of this approach is feasible to develop a cheap, sensitive and portable device for multiplexed diagnoses of different proteins. This method is simple, selective and reproducible for trace protein analysis and can be extended to study protein/protein, peptide/protein, and DNA/ protein interactions.

  5. Crystallization of hollow mesoporous silica nanoparticles.

    PubMed

    Drisko, Glenna L; Carretero-Genevrier, Adrian; Perrot, Alexandre; Gich, Martí; Gàzquez, Jaume; Rodriguez-Carvajal, Juan; Favre, Luc; Grosso, David; Boissière, Cédric; Sanchez, Clément

    2015-03-11

    Complex 3D macrostructured nanoparticles are transformed from amorphous silica into pure polycrystalline α-quartz using catalytic quantities of alkaline earth metals as devitrifying agent. Walls as thin as 10 nm could be crystallized without losing the architecture of the particles. The roles of cation size and the mol% of the incorporated devitrifying agent in crystallization behavior are studied, with Mg(2+), Ca(2+), Sr(2+) and Ba(2+) all producing pure α-quartz under certain conditions. PMID:25503642

  6. Cobalt silica magnetic nanoparticles with functional surfaces

    NASA Astrophysics Data System (ADS)

    Vadala, Michael L.; Zalich, Michael A.; Fulks, David B.; St. Pierre, Tim G.; Dailey, James P.; Riffle, Judy S.

    2005-05-01

    Cobalt nanoparticles encased in polysiloxane block copolymers have been heated at 600-700 °C to form protective shells around the particles, which contain crosslinked Si-O structures, and to anneal the cobalt. Methods to functionalize and modify the surfaces of the pyrolyzed/annealed silica-cobalt complexes with amines, isocyanates, poly(ethylene oxide), poly( L-lactide) and polydimethylsiloxane (PDMS) are presented.

  7. Mesoporous silica nanoparticles for active corrosion protection.

    PubMed

    Borisova, Dimitriya; Möhwald, Helmuth; Shchukin, Dmitry G

    2011-03-22

    This work presents the synthesis of monodisperse, mesoporous silica nanoparticles and their application as nanocontainers loaded with corrosion inhibitor (1H-benzotriazole (BTA)) and embedded in hybrid SiOx/ZrOx sol-gel coating for the corrosion protection of aluminum alloy. The developed porous system of mechanically stable silica nanoparticles exhibits high surface area (∼1000 m2·g(-1)), narrow pore size distribution (d∼3 nm), and large pore volume (∼1 mL·g(-1)). As a result, a sufficiently high uptake and storage of the corrosion inhibitor in the mesoporous nanocontainers was achieved. The successful embedding and homogeneous distribution of the BTA-loaded monodisperse silica nanocontainers in the passive anticorrosive SiOx/ZrOx film improve the wet corrosion resistance of the aluminum alloy AA2024 in 0.1 M sodium chloride solution. The enhanced corrosion protection of this newly developed active system in comparison to the passive sol-gel coating was observed during a simulated corrosion process by the scanning vibrating electrode technique (SVET). These results, as well as the controlled pH-dependent release of BTA from the mesoporous silica nanocontainers without additional polyelectrolyte shell, suggest an inhibitor release triggered by the corrosion process leading to a self-healing effect. PMID:21344888

  8. A Pd/silica composite with highly uniform Pd nanoparticles on silica lamella via layered silicate

    NASA Astrophysics Data System (ADS)

    Hao, Jing; Cui, Zhi-Min; Cao, Chang-Yan; Song, Weiguo

    2016-08-01

    Pd nanoparticles was loaded on silica lamella via layered silicate through a simple ion-exchange and in situ reduction method. The obtained Pd/silica composite has Pd nanoparticles with highly uniform size dispersed well on the silica lamella. The Pd/silica composite is active and recoverable catalyst for the hydrogenation reaction and the reaction can be completed in a short time of 2 h at room temperature and 1 atm H2 pressure.

  9. Glycyrrhetinic acid-modified chitosan nanoparticles enhanced the effect of 5-fluorouracil in murine liver cancer model via regulatory T-cells

    PubMed Central

    Cheng, Mingrong; Xu, Hongzhi; Wang, Yong; Chen, Houxiang; He, Bing; Gao, Xiaoyan; Li, Yingchun; Han, Jiang; Zhang, Zhiping

    2013-01-01

    Modified chitosan nanoparticles are a promising platform for drug, such as 5-fluorouracil (5-FU), gene, and vaccine delivery. Here, we used chitosan and hepatoma cell-specific binding molecule glycyrrhetinic acid (GA) to synthesize glycyrrhetinic acid-modified chitosan (GA-CTS). The synthetic product was confirmed by infrared spectroscopy and hydrogen nuclear magnetic resonance. By combining GA-CTS and 5-FU, we obtained a GA-CTS/5-FU nanoparticle, with a particle size of 193.7 nm, drug loading of 1.56%, and a polydispersity index of 0.003. The GA-CTS/5-FU nanoparticle provided a sustained-release system comprising three distinct phases of quick, steady, and slow release. In vitro data indicated that it had a dose- and time-dependent anticancer effect. The effective drug exposure time against hepatic cancer cells was increased in comparison with that observed with 5-FU. In vivo studies on an orthotropic liver cancer mouse model demonstrated that GA-CTS/5-FU significantly inhibited cancer cell proliferation, resulting in increased survival time. The antitumor mechanisms for GA-CTS/5-FU nanoparticle were possibly associated with an increased expression of regulatory T-cells, decreased expression of cytotoxic T-cell and natural killer cells, and reduced levels of interleukin-2 and interferon gamma. PMID:24187487

  10. Luminescent Silica Nanoparticles for cancer diagnosis

    PubMed Central

    Montalti, Marco; Petrizza, Luca; Rampazzo, Enrico; Zaccheroni, Nelsi; Marchiò, Serena

    2015-01-01

    Fluorescence imaging techniques are becoming essential in preclinical investigations, and the research of suitable tools for in vivo measurements is gaining more and more importance and attention. Nanotechnology entered the field to try to find solutions for many limitation at the state of the art, and luminescent nanoparticles (NPs) are one of the most promising materials proposed for future diagnostic implementation. NPs constitute also a versatile platform that can allow facile multi-functionalization to perform multimodal imaging or theranostic (simultaneous diagnosis and therapy). In this contribution we have focussed our attention only on dye doped silica or silica-based NPs conjugated with targeting moieties to enable specific cancer cells imaging and differentiation, even if also a few non targeted systems have been cited and discussed for completeness. We have summarized common synthetic approaches to these materials and then surveyed the most recent imaging applications of silica-based nanoparticles in cancer. The field of theranostic is so important and stimulating that, even if it is not the central topic of this paper, we have included some significant examples. We have then concluded with short hints on systems already in clinical trials and examples of specific applications in children tumours. This review tries to describe and discuss, through focussed examples, the great potentialities of these materials in the medical field, with the aim to encourage further research to implement applications that are still rare. PMID:23458621

  11. A bioinspired strategy for surface modification of silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Tian, Jianwen; Zhang, Haoxuan; Liu, Meiying; Deng, Fengjie; Huang, Hongye; Wan, Qing; Li, Zhen; Wang, Ke; He, Xiaohui; Zhang, Xiaoyong; Wei, Yen

    2015-12-01

    Silica nanoparticles have become one of the most promising nanomaterials for a vast of applications. In this work, a novel strategy for surface modification of silica nanoparticles has been developed for the first time via combination of mussel inspired chemistry and Michael addition reaction. In this procedure, thin polydopamine (PDA) films were first coated on the bare silica nanoparticles via self-polymerization of dopamine in alkaline condition. And then amino-containing polymers were introduced onto the PDA coated silica nanoparticles through Michael addition reaction, that are synthesized from free radical polymerization using poly(ethylene glycol) methyl methacrylate (PEGMA) and N-(3-aminopropyl) methacrylamide (NAPAM) as monomers and ammonium persulfate as the initiator. The successful modification of silica nanoparticles was evidenced by a series of characterization techniques. As compared with the bare silica nanoparticles, the polymers modified silica nanoparticles showed remarkable enhanced dispersibility in both aqueous and organic solution. This strategy is rather simple, effective and versatile. Therefore, it should be of specific importance for further applications of silica nanoparticles and will spark great research attention of scientists from different fields.

  12. Reliable methods for silica coating of Au nanoparticles.

    PubMed

    Pastoriza-Santos, Isabel; Liz-Marzán, Luis M

    2013-01-01

    The inherent properties of silica, such as optical transparency, high biocompatibility, chemical and colloidal stability, controllable porosity, and easy surface modification, provide silica materials with a tremendous potential in biomedicine. Therefore, the coating of Au nanoparticles with silica largely contributes to enhance the important applications of metal nanoparticles in biomedicine. We describe in this chapter a number of reliable strategies that have been reported for silica coating of different types of Au nanoparticles. All descriptions are based on tested protocols and are expected to provide a reference for scientists with an interest in this field. PMID:23918330

  13. Synthesis and surface functionalization of silica nanoparticles for nanomedicine

    PubMed Central

    Liberman, Alexander; Mendez, Natalie; Trogler, William C.; Kummel, Andrew C.

    2014-01-01

    There are a wide variety of silica nanoformulations being investigated for biomedical applications. Silica nanoparticles can be produced using a wide variety of synthetic techniques with precise control over their physical and chemical characteristics. Inorganic nanoformulations are often criticized or neglected for their poor tolerance; however, extensive studies into silica nanoparticle biodistributions and toxicology have shown that silica nanoparticles may be well tolerated, and in some case are excreted or are biodegradable. Robust synthetic techniques have allowed silica nanoparticles to be developed for applications such as biomedical imaging contrast agents, ablative therapy sensitizers, and drug delivery vehicles. This review explores the synthetic techniques used to create and modify an assortment of silica nanoformulations, as well as several of the diagnostic and therapeutic applications. PMID:25364083

  14. Synthesis and surface functionalization of silica nanoparticles for nanomedicine

    NASA Astrophysics Data System (ADS)

    Liberman, Alexander; Mendez, Natalie; Trogler, William C.; Kummel, Andrew C.

    2014-09-01

    There are a wide variety of silica nanoformulations being investigated for biomedical applications. Silica nanoparticles can be produced using a wide variety of synthetic techniques with precise control over their physical and chemical characteristics. Inorganic nanoformulations are often criticized or neglected for their poor tolerance; however, extensive studies into silica nanoparticle biodistributions and toxicology have shown that silica nanoparticles may be well tolerated, and in some case are excreted or are biodegradable. Robust synthetic techniques have allowed silica nanoparticles to be developed for applications such as biomedical imaging contrast agents, ablative therapy sensitizers, and drug delivery vehicles. This review explores the synthetic techniques used to create and modify an assortment of silica nanoformulations, as well as several of the diagnostic and therapeutic applications.

  15. Continuous polymer nanocoating on silica nanoparticles.

    PubMed

    Chen, Dengyue; Singh, Dhananjay; Sirkar, Kamalesh K; Zhu, Jiangtao; Pfeffer, Robert

    2014-07-01

    Continuous polymer coating of nanoparticles is of interest in many industries such as pharmaceuticals, cosmetics, food, and electronics. Here we introduce a polymer coating/precipitation technique to achieve a uniform and controllable nanosize polymer coating on nanoparticles in a continuous manner. The utility of this technique is demonstrated by coating Aerosil silica nanoparticles (SNPs) of diameter 12 nm with the polymer Eudragit RL 100. Both hydrophilic and hydrophobic SNPs were successfully coated. After determining the cloud point of an acetone solution of the polymer containing a controlled amount of the nonsolvent water, the solid hollow fiber cooling crystallization (SHFCC) technique was employed to continuously coat SNPs with the polymer. A suspension of the SNPs in an acetone-water solution of the polymer containing a surfactant was pumped through the lumen of solid polypropylene hollow fibers in a SHFCC device; cold liquid was circulated on the shell side. Because of rapid cooling-induced supersaturation and heterogeneous nucleation, precipitated polymers will coat the nanoparticles. The thickness and morphology of the nanocoating and the particle size distribution of the coated SNPs were analyzed by scanning transmission electron microscopy (STEM) with electron energy loss spectroscopy (EELS), thermogravimetric analysis (TGA), and dynamic light scattering (DLS). Results indicate that uniformly polymer-coated SNPs can be obtained from the SHFCC device after suitable post-treatments. The technique is also easily scalable by increasing the number of hollow fibers in the SHFCC device. PMID:24903705

  16. Silica and titanium dioxide nanoparticles cause pregnancy complications in mice

    NASA Astrophysics Data System (ADS)

    Yamashita, Kohei; Yoshioka, Yasuo; Higashisaka, Kazuma; Mimura, Kazuya; Morishita, Yuki; Nozaki, Masatoshi; Yoshida, Tokuyuki; Ogura, Toshinobu; Nabeshi, Hiromi; Nagano, Kazuya; Abe, Yasuhiro; Kamada, Haruhiko; Monobe, Youko; Imazawa, Takayoshi; Aoshima, Hisae; Shishido, Kiyoshi; Kawai, Yuichi; Mayumi, Tadanori; Tsunoda, Shin-Ichi; Itoh, Norio; Yoshikawa, Tomoaki; Yanagihara, Itaru; Saito, Shigeru; Tsutsumi, Yasuo

    2011-05-01

    The increasing use of nanomaterials has raised concerns about their potential risks to human health. Recent studies have shown that nanoparticles can cross the placenta barrier in pregnant mice and cause neurotoxicity in their offspring, but a more detailed understanding of the effects of nanoparticles on pregnant animals remains elusive. Here, we show that silica and titanium dioxide nanoparticles with diameters of 70 nm and 35 nm, respectively, can cause pregnancy complications when injected intravenously into pregnant mice. The silica and titanium dioxide nanoparticles were found in the placenta, fetal liver and fetal brain. Mice treated with these nanoparticles had smaller uteri and smaller fetuses than untreated controls. Fullerene molecules and larger (300 and 1,000 nm) silica particles did not induce these complications. These detrimental effects are linked to structural and functional abnormalities in the placenta on the maternal side, and are abolished when the surfaces of the silica nanoparticles are modified with carboxyl and amine groups.

  17. Antioxidative and antiinflammatory activities of quercetin-loaded silica nanoparticles.

    PubMed

    Lee, Ga Hyun; Lee, Sung June; Jeong, Sang Won; Kim, Hyun-Chul; Park, Ga Young; Lee, Se Geun; Choi, Jin Hyun

    2016-07-01

    Utilizing the biological activities of compounds by encapsulating natural components in stable nanoparticles is an important strategy for a variety of biomedical and healthcare applications. In this study, quercetin-loaded silica nanoparticles were synthesized using an oil-in-water microemulsion method, which is a suitable system for producing functional nanoparticles of controlled size and shape. The resulting quercetin-loaded silica nanoparticles were spherical, highly monodispersed, and stable in an aqueous system. Superoxide radical scavenging effects were found for the quercetin-loaded silica nanoparticles as well as free quercetin. The quercetin-loaded silica nanoparticles showed cell viability comparable to that of the controls. The amounts of proinflammatory cytokines produced by macrophages, such as interleukin 1 beta, interleukin 6, and tumor necrosis factor alpha, were reduced significantly for the quercetin-loaded silica nanoparticles. These results suggest that the antioxidative and antiinflammatory activities of quercetin are maintained after encapsulation in silica. Silica nanoparticles can be used for the effective and stable incorporation of biologically active natural components into composite biomaterials. PMID:27038916

  18. Colorimetric detection of Bi (III) in water and drug samples using pyridine-2,6-dicarboxylic acid modified silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Mohammadi, Somayeh; Khayatian, Gholamreza

    2015-09-01

    A new selective, simple, fast and sensitive method is developed for sensing assay of Bi (III) using pyridine-2,6-dicarboxylic acid or dipicolinic acid (DPA) modified silver nanoparticles (DPA-AgNPs). Silver nanoparticles (AgNPs) were synthesized by reducing silver nitrate (AgNO3) with sodium borohydride (NaBH4) in the presence of DPA. Bismuth detection is based on color change of nanoparticle solution from yellow to red that is induced in the presence of Bi (III). Aggregation of DPA-AgNPs has been confirmed with UV-vis absorption spectra and transmission electron microscopy (TEM) images. Under the optimized conditions, a good linear relationship (correlation coefficient r = 0.995) is obtained between the absorbance ratio (A525/A390) and the concentration of Bi (III) in the 0.40-8.00 μM range. This colorimetric probe allows Bi (III) to be rapidly quantified with a 0.01 μM limit of detection. The present method successfully applied to determine bismuth in real water and drug samples. Recoveries of water samples were in the range of 91.2-99.6%.

  19. Colorimetric detection of Bi (III) in water and drug samples using pyridine-2,6-dicarboxylic acid modified silver nanoparticles.

    PubMed

    Mohammadi, Somayeh; Khayatian, Gholamreza

    2015-09-01

    A new selective, simple, fast and sensitive method is developed for sensing assay of Bi (III) using pyridine-2,6-dicarboxylic acid or dipicolinic acid (DPA) modified silver nanoparticles (DPA-AgNPs). Silver nanoparticles (AgNPs) were synthesized by reducing silver nitrate (AgNO3) with sodium borohydride (NaBH4) in the presence of DPA. Bismuth detection is based on color change of nanoparticle solution from yellow to red that is induced in the presence of Bi (III). Aggregation of DPA-AgNPs has been confirmed with UV-vis absorption spectra and transmission electron microscopy (TEM) images. Under the optimized conditions, a good linear relationship (correlation coefficient r=0.995) is obtained between the absorbance ratio (A525/A390) and the concentration of Bi (III) in the 0.40-8.00 μM range. This colorimetric probe allows Bi (III) to be rapidly quantified with a 0.01 μM limit of detection. The present method successfully applied to determine bismuth in real water and drug samples. Recoveries of water samples were in the range of 91.2-99.6%. PMID:25919329

  20. Hyaluronic Acid-Modified Cationic Lipid-PLGA Hybrid Nanoparticles as a Nanovaccine Induce Robust Humoral and Cellular Immune Responses.

    PubMed

    Liu, Lanxia; Cao, Fengqiang; Liu, Xiaoxuan; Wang, Hai; Zhang, Chao; Sun, Hongfan; Wang, Chun; Leng, Xigang; Song, Cunxian; Kong, Deling; Ma, Guilei

    2016-05-18

    Here, we investigated the use of hyaluronic acid (HA)-decorated cationic lipid-poly(lactide-co-glycolide) acid (PLGA) hybrid nanoparticles (HA-DOTAP-PLGA NPs) as vaccine delivery vehicles, which were originally developed for the cytosolic delivery of genes. Our results demonstrated that after the NPs uptake by dendritic cells (DCs), some of the antigens that were encapsulated in HA-DOTAP-PLGA NPs escaped to the cytosolic compartment, and whereas some of the antigens remained in the endosomal/lysosomal compartment, where both MHC-I and MHC-II antigen presentation occurred. Moreover, HA-DOTAP-PLGA NPs led to the up-regulation of MHC, costimulatory molecules, and cytokines. In vivo experiments further revealed that more powerful immune responses were induced from mice immunized with HA-DOTAP-PLGA NPs when compared with cationic lipid-PLGA nanoparticles and free ovalbumin (OVA); the responses included antigen-specific CD4(+) and CD8(+) T-cell responses, the production of antigen-specific IgG antibodies and the generation of memory CD4(+) and CD8(+) T cells. Overall, these data demonstrate the high potential of HA-DOTAP-PLGA NPs for use as vaccine delivery vehicles to elevate cellular and humoral immune responses. PMID:27088457

  1. Bacteriostatic and anti-collagenolytic dental materials through the incorporation of polyacrylic acid modified CuI nanoparticles

    SciTech Connect

    Renne, Walter George; Mennito, Anthony Samuel; Schmidt, Michael Gerard; Vuthiganon, Jompobe; Chumanov, George

    2015-05-19

    Provided are antibacterial and antimicrobial surface coatings and dental materials by utilizing the antimicrobial properties of copper chalcogenide and/or copper halide (CuQ, where Q=chalcogens including oxygen, or halogens, or nothing). An antimicrobial barrier is created by incorporation of CuQ nanoparticles of an appropriate size and at a concentration necessary and sufficient to create a unique bioelectrical environment. The unique bioelectrical environment results in biocidal effectiveness through a multi-factorial mechanism comprising a combination of the intrinsic quantum flux of copper (Cu.sup.0, Cu.sup.1+, Cu.sup.2+) ions and the high surface-to-volume electron sink facilitated by the nanoparticle. The result is the constant quantum flux of copper which manifests and establishes the antimicrobial environment preventing or inhibiting the growth of bacteria. The presence of CuQ results in inhibiting or delaying bacterial destruction and endogenous enzymatic breakdown of the zone of resin inter-diffusion, the integrity of which is essential for dental restoration longevity.

  2. Phase behavior and rheological characterization of silica nanoparticle gel

    NASA Astrophysics Data System (ADS)

    Metin, Cigdem O.; Rankin, Kelli M.; Nguyen, Quoc P.

    2014-01-01

    Preferential injection into high permeability thief zones or fractures can result in early breakthrough at production wells and large unswept areas of high oil saturation, which impact the economic life of a well. A variety of conformance control techniques, including polymer and silica gel treatments, have been designed to block flow through the swept zones. Over a certain range of salinities, silica nanoparticle suspensions form a gel in bulk phase behavior tests. These gels have potential for in situ flow diversion, but in situ flow tests are required to determine their applicability. To determine the appropriate scope of the in situ tests, it is necessary to obtain an accurate description of nanoparticle phase behavior and gel rheology. In this paper, the equilibrium phase behavior of silica nanoparticle solutions in the presence of sodium chloride (NaCl) is presented with four phase regions classified as a function of salinity and nanoparticle concentration. Once the gelation window was clearly defined, rheology experiments of silica nanoparticle gels were also carried out. Gelation time decreases exponentially as a function of silica concentration, salinity, and temperature. Following a power law behavior, the storage modulus, G', increases with particle concentration. Steady shear measurements show that silica nanoparticle gels exhibit non-Newtonian, shear thinning behavior. This comprehensive study of the silica nanoparticle gels has provided a clear path forward for in situ tests to determine the gel's applicability for conformance control operations.

  3. Lactobionic acid-modified dendrimer-entrapped gold nanoparticles for targeted computed tomography imaging of human hepatocellular carcinoma.

    PubMed

    Liu, Hui; Wang, Han; Xu, Yanhong; Guo, Rui; Wen, Shihui; Huang, Yunpeng; Liu, Weina; Shen, Mingwu; Zhao, Jinglong; Zhang, Guixiang; Shi, Xiangyang

    2014-05-14

    Development of novel nanomaterial-based contrast agents for targeted computed tomography (CT) imaging of tumors still remains a great challenge. Here we describe a novel approach to fabricating lactobionic acid (LA)-modified dendrimer-entrapped gold nanoparticles (LA-Au DENPs) for in vitro and in vivo targeted CT imaging of human hepatocellular carcinoma. In this study, amine-terminated poly(amidoamine) dendrimers of generation 5 pre-modified with fluorescein isothiocyanate and poly(ethylene glycol)-linked LA were employed as templates to form Au nanoparticles. The remaining dendrimer terminal amines were subjected to an acetylation reaction to form LA-Au DENPs. The prepared LA-Au DENPs were characterized via different methods. Our results reveal that the multifunctional Au DENPs with a Au core size of 2.7 nm have good stability under different pH (5-8) and temperature (4-50 °C) conditions and in different aqueous media, and are noncytotoxic to normal cells but cytotoxic to the targeted hepatocarcinoma cells in the given concentration range. In vitro flow cytometry data show that the LA-Au DENPs can be specifically uptaken by a model hepatocarcinoma cell line overexpressing asialoglycoprotein receptors through an active receptor-mediated targeting pathway. Importantly, the LA-Au DENPs can be used as a highly effective nanoprobe for specific CT imaging of hepatocarcinoma cells in vitro and the xenoplanted tumor model in vivo. The developed LA-Au DENPs with X-ray attenuation property greater than clinically employed iodine-based CT contrast agents hold a great promise to be used as a nanoprobe for targeted CT imaging of human hepatocellular carcinoma. PMID:24712914

  4. Urocanic acid-modified chitosan nanoparticles can confer anti-inflammatory effect by delivering CD98 siRNA to macrophages.

    PubMed

    Xiao, Bo; Ma, Panpan; Viennois, Emilie; Merlin, Didier

    2016-07-01

    CD98 plays an important role in the development and progression of inflammation. Here, CD98 siRNA (siCD98) was complexed with urocanic acid-modified chitosan (UAC) to form nanoparticles (NPs), which were transfected into Raw 264.7 macrophages in an effort to convey anti-inflammatory effects. Characterization showed that the generated NPs had a desirable particle size (156.0-247.1nm), a slightly positive zeta potential (15.8-17.5mV), and no apparent cytotoxicity against Raw 264.7 macrophages and colon-26 cells compared to control NPs fabricated by Oligofectamine (OF) and siRNA. Cellular uptake experiments demonstrated that macrophages exhibited a time-dependent accumulation profile of UAC/siRNA NPs. Further in vitro gene silencing experiments revealed that UAC/siCD98 NPs with a weight ratio of 60:1 yielded the most efficient knockdowns of CD98 and the pro-inflammatory cytokine, TNF-α. Indeed, the RNAi efficiency obtained with our NPs was even higher than that of the positive control OF/siCD98 NPs. These results suggest that UAC/siCD98 NPs might be a safe, efficient and promising candidate for the treatment of inflammatory disease. PMID:27011348

  5. Hyaluronic acid-modified magnetic iron oxide nanoparticles for MR imaging of surgically induced endometriosis model in rats.

    PubMed

    Zhang, He; Li, Jingchao; Sun, Wenjie; Hu, Yong; Zhang, Guofu; Shen, Mingwu; Shi, Xiangyang

    2014-01-01

    Endometriosis is defined as the presence of endometrial tissue outside the uterine, which may affect nearly 60% of women in reproductive age. Deep infiltrating endometriosis (DIE) defined as an endometriotic lesion penetrating into the retroperitoneal space or the wall of the pelvic organs to a depth of at least 5 mm represents the most diagnostic challenge. Herein, we reported the use of hyaluronic acid (HA)-modified magnetic iron oxide nanoparticles (HA-Fe3O4 NPs) for magnetic resonance (MR) imaging of endometriotic lesions in the rodent model. Sixteen endometriotic lesions were surgically induced in eight rats by autologous transplantation. Four weeks after lesion induction, three rats were scanned via MR imaging after tail vein injection of the HA-Fe3O4 NPs. Accordingly, the remaining five mice were sacrificed in the corresponding time points. The ectopic uterine tissues (EUTs) were confirmed by histological analysis. Quantification of Fe in the EUT was also performed by inductively coupled plasma-optical emission spectroscopy. Our results showed that by using the HA-Fe3O4 NPs, the EUTs were able to be visualized via T2-weighted MR imaging at 2 hours post injection, corroborating the Prussian blue staining results. The developed HA-Fe3O4 NPs could be used as negative contrast agents for sensitively detecting endometriosis in a mouse model and may be applied for future hyperthermia treatment of endometriosis. PMID:24722347

  6. A facile and effective immobilization of glucose oxidase on tannic acid modified CoFe2O4 magnetic nanoparticles.

    PubMed

    Altun, Seher; Çakıroğlu, Bekir; Özacar, Münteha; Özacar, Mahmut

    2015-12-01

    This article presents a study of glucose oxidase (GOx) immobilization by employing tannic acid (TA) modified-CoFe2O4 (CFO) magnetic nanoparticles which demonstrates novel aspect for enzyme immobilization. By using the strong protein and tannic acid binding, GOx immobilization was carried out via physical adsorption in a simpler way compared with the other immobilization methods which require various chemicals and complicated procedures which is difficult, expensive, time-consuming, and destructive to the enzyme structure. CFO was synthesized by hydrothermal synthesis and modified with TA to immobilize GOx. The immobilized GOx demonstrated maximum catalytic activity at pH 6.5 and 45 °C. The samples were characterized by vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), zeta potential, and fourier transform infrared spectroscopy (FTIR), all of which confirm the surface modification of CFO and GOx immobilization. Also, field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) were performed to demonstrate the surface morphology and chemical structure of samples. According to the Lineweaver-Burk plot, GOx possessed lower affinity to glucose after immobilization, and the Michelis-Menten constant (KM) of immobilized and free GOx were found to be 50.05 mM and 28.00 mM, respectively. The immobilized GOx showed excellent reusability, and even after 8 consecutive activity assay runs, the immobilized GOx maintained ca. 60% of its initial activity. PMID:26562188

  7. Insitu grafting silica nanoparticles reinforced nanocomposite hydrogels

    NASA Astrophysics Data System (ADS)

    Yang, Jun; Han, Chun-Rui; Duan, Jiu-Fang; Xu, Feng; Sun, Run-Cang

    2013-10-01

    Highly flexible nanocomposite hydrogels were prepared by using silica nanoparticles (SNPs) as fillers and multi-functional cross-links to graft hydrophilic poly(acrylic acid) (PAA) by free radical polymerization from an aqueous solution. The SNPs were collected by neighboring polymer chains and dispersed uniformly within a PAA matrix. The mechanical properties of the nanocomposite hydrogels were tailored by the concentration of SNPs according to the percolation model. It was proposed that covalent bonds of adsorbed chains on the filler surface resulted in the formation of a shell of an immobilized glassy layer and trapped entanglements, where the glassy polymer layer greatly enhanced the elastic modulus and the release of trapped entanglements at deformation contributed to the viscoelastic properties.Highly flexible nanocomposite hydrogels were prepared by using silica nanoparticles (SNPs) as fillers and multi-functional cross-links to graft hydrophilic poly(acrylic acid) (PAA) by free radical polymerization from an aqueous solution. The SNPs were collected by neighboring polymer chains and dispersed uniformly within a PAA matrix. The mechanical properties of the nanocomposite hydrogels were tailored by the concentration of SNPs according to the percolation model. It was proposed that covalent bonds of adsorbed chains on the filler surface resulted in the formation of a shell of an immobilized glassy layer and trapped entanglements, where the glassy polymer layer greatly enhanced the elastic modulus and the release of trapped entanglements at deformation contributed to the viscoelastic properties. Electronic supplementary information (ESI) available: FTIR spectra of SNP after silane treatment, dynamic oscillatory shear measurements as a function of frequency, constrained polymer chain analysis by a change in the peak height in loss factor spectra, molecular weight of grafted chains at different stages of gelation, prediction of the SNP reinforcing mechanism in the

  8. Functionalized mesoporous silica nanoparticles for oral delivery of budesonide

    NASA Astrophysics Data System (ADS)

    Yoncheva, K.; Popova, M.; Szegedi, A.; Mihaly, J.; Tzankov, B.; Lambov, N.; Konstantinov, S.; Tzankova, V.; Pessina, F.; Valoti, M.

    2014-03-01

    Non-functionalized and amino-functionalized mesoporous silica nanoparticle were loaded with anti-inflammatory drug budesonide and additionally post-coated with bioadhesive polymer (carbopol). TEM images showed spherical shape of the nanoparticles and slightly higher polydispersity after coating with carbopol. Nitrogen physisorption and thermogravimetic analysis revealed that more efficient loading and incorporation into the pores of nanoparticles was achieved with the amino-functionalized silica carrier. Infrared spectra indicated that the post-coating of these nanoparticles with carbopol led to the formation of bond between amino groups of the functionalized carrier and carboxyl groups of carbopol. The combination of amino-functionalization of the carrier with the post-coating of the nanoparticles sustained budesonide release. Further, an in vitro model of inflammatory bowel disease showed that the cytoprotective effect of budesonide loaded in the post-coated silica nanoparticles on damaged HT-29 cells was more pronounced compared to the cytoprotection obtained with pure budesonide.

  9. Multifunctional mesoporous silica nanocomposite nanoparticles for theranostic applications.

    PubMed

    Lee, Ji Eun; Lee, Nohyun; Kim, Taeho; Kim, Jaeyun; Hyeon, Taeghwan

    2011-10-18

    Clever combinations of different types of functional nanostructured materials will enable the development of multifunctional nanomedical platforms for multimodal imaging or simultaneous diagnosis and therapy. Mesoporous silica nanoparticles (MSNs) possess unique structural features such as their large surface areas, tunable nanometer-scale pore sizes, and well-defined surface properties. Therefore, they are ideal platforms for constructing multifunctional materials that incorporate a variety of functional nanostructured materials. In this Account, we discuss recent progress by our group and other researchers in the design and fabrication of multifunctional nanocomposite nanoparticles based on mesoporous silica nanostructures for applications to simultaneous diagnosis and therapy. Versatile mesoporous silica-based nanocomposite nanoparticles were fabricated using various methods. Here, we highlight two synthetic approaches: the encapsulation of functional nanoparticles within a mesoporous silica shell and the assembly of nanoparticles on the surface of silica nanostructures. Various nanoparticles were encapsulated in MSNs using surfactants as both phase transfer agents and pore-generating templates. Using MSNs as a scaffold, functional components such as magnetic nanoparticles and fluorescent dyes have been integrated within these systems to generate multifunctional nanocomposite systems that maintain their individual functional characteristics. For example, uniform mesoporous dye-doped silica nanoparticles immobilized with multiple magnetite nanocrystals on their surfaces have been fabricated for their use as a vehicle capable of simultaneous magnetic resonance (MR) and fluorescence imaging and drug delivery. The resulting nanoparticle-incorporated MSNs were then tested in mice with tumors. These in vivo experiments revealed that these multifunctional nanocomposite nanoparticles were delivered to the tumor sites via passive targeting. These nanocomposite

  10. Selective porous gates made from colloidal silica nanoparticles

    PubMed Central

    Avetta, Paola; Calza, Paola; Fabbri, Debora; Magnacca, Giuliana; Scalarone, Dominique

    2015-01-01

    Summary Highly selective porous films were prepared by spin-coating deposition of colloidal silica nanoparticles on an appropriate macroporous substrate. Silica nanoparticles very homogenous in size were obtained by sol–gel reaction of a metal oxide silica precursor, tetraethyl orthosilicate (TEOS), and using polystyrene-block-poly(ethylene oxide) (PS-b-PEO) copolymers as soft-templating agents. Nanoparticles synthesis was carried out in a mixed solvent system. After spin-coating onto a macroporous silicon nitride support, silica nanoparticles were calcined under controlled conditions. An organized nanoporous layer was obtained characterized by a depth filter-like structure with internal porosity due to interparticle voids. Permeability and size-selectivity were studied by monitoring the diffusion of probe molecules under standard conditions and under the application of an external stimulus (i.e., electric field). Promising results were obtained, suggesting possible applications of these nanoporous films as selective gates for controlled transport of chemical species in solution. PMID:26665082

  11. Elastic Phase Response of Silica Nanoparticles Buried in Soft Matter

    SciTech Connect

    Tetard, Laurene; Passian, Ali; Lynch, Rachel M; Voy, Brynn H; Shekhawat, Gajendra; Dravid, Vinayak; Thundat, Thomas George

    2008-01-01

    Tracking the uptake of nanomaterials by living cells is an important component in assessing both potential toxicity and in designing future materials for use in vivo. We show that the difference in the local elasticity at the site of silica (SiO{sub 2}) nanoparticles confined within a macrophage enables functional ultrasonic interactions. By elastically exciting the cell, a phase perturbation caused by the buried SiO{sub 2} nanoparticles was detected and used to map the subsurface populations of nanoparticles. Localization and mapping of stiff chemically synthesized silica nanoparticles within the cellular structures of a macrophage are important in basic as well as applied studies.

  12. Functionalized mesoporous silica nanoparticles for oral delivery of budesonide

    SciTech Connect

    Yoncheva, K.; Popova, M.; Szegedi, A.; Mihaly, J.; Tzankov, B.; Lambov, N.; Konstantinov, S.; Tzankova, V.; Pessina, F.; Valoti, M.

    2014-03-15

    Non-functionalized and amino-functionalized mesoporous silica nanoparticle were loaded with anti-inflammatory drug budesonide and additionally post-coated with bioadhesive polymer (carbopol). TEM images showed spherical shape of the nanoparticles and slightly higher polydispersity after coating with carbopol. Nitrogen physisorption and thermogravimetic analysis revealed that more efficient loading and incorporation into the pores of nanoparticles was achieved with the amino-functionalized silica carrier. Infrared spectra indicated that the post-coating of these nanoparticles with carbopol led to the formation of bond between amino groups of the functionalized carrier and carboxyl groups of carbopol. The combination of amino-functionalization of the carrier with the post-coating of the nanoparticles sustained budesonide release. Further, an in vitro model of inflammatory bowel disease showed that the cytoprotective effect of budesonide loaded in the post-coated silica nanoparticles on damaged HT-29 cells was more pronounced compared to the cytoprotection obtained with pure budesonide. -- Graphical abstract: Silica mesoporous MCM-41 particles were amino-functionalized, loaded with budesonide and post-coated with bioadhesive polymer (carbopol) in order to achieve prolonged residence of anti-inflammatory drug in GIT. Highlights: • Higher drug loading in amino-functionalized mesoporous silica. • Amino-functionalization and post-coating of the nanoparticles sustained drug release. • Achievement of higher cytoprotective effect with drug loaded into the nanoparticles.

  13. Nanomachines on Porous Silica Nanoparticles for Cargo Delivery

    NASA Astrophysics Data System (ADS)

    Tarn, Derrick

    The field of nanomachines based on mesoporous and microporous silica nanoparticles is a relatively new one, but has quickly gained widespread popularity due to their large potential applications. These porous nanomaterials can both carry and release a therapeutic drug molecule at a targeted location. In order to regulate the movement of cargo, nanomachines are designed and assembled onto the silica nanoparticle, ultimately creating a delivery system on the nanoscale that is capable of a stimulus-responsive delivery of its cargo. This dissertation focuses on the design, synthesis and assembly of nanomachines on both meso- and microporous silica nanoparticles to achieve the goal of cargo delivery. The six chapters of this dissertation are presented as follows: 1) the design, synthesis and modification of silica nanoparticles for their use in biology, 2) a light activated, reversible nanovalve assembled on mesoporous silica nanoparticles to achieve a size-selective cargo delivery, 3) biological applications and the delivery of anti-cancer drugs using a pseudorotaxane-based light activated nanovalve, 4) a nanogate machine that is capable of the storage and delivery of both small metal ions and useful organic cargo molecules, 5) biological applications of the nanogate machine in order to deliver calcium ions to cancerous cells to induce cell apoptosis, and 6) thin wax coated microporous silica nanoparticles that are capable of delivering small ions including oxidizers.

  14. Fluorescence anisotropy metrology of electrostatically and covalently labelled silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Yip, Philip; Karolin, Jan; Birch, David J. S.

    2012-08-01

    We compare determining the size of silica nanoparticles using the time-resolved fluorescence anisotropy decay of dye molecules when electrostatically and covalently bound to stable silica nanoparticles. Covalent labelling is shown to offer advantages by simplifying the dye rotational kinetics and the appropriateness of various kinetic models is discussed. Silica nanoparticles produced using Stöber synthesis of tetraethylorthosilicate (TEOS) are found to be controllable between ˜3.1 and 3.8 nm radius by adjusting the relative water:TEOS concentration. Covalent labelling with fluorescein 5(6)-isothiocyanate (FITC) bound to (3-aminopropyl) trimethoxysilane (FITC-APS) predicts a larger particle than electrostatically labelling with rhodamine 6G. The difference is attributed to the presence of an additional depolarization mechanism to Brownian rotation of the nanoparticle and dye wobbling with electrostatic labelling in the form of dye diffusion on the surface of the nanoparticle.

  15. Mechanism of cellular uptake of genotoxic silica nanoparticles

    PubMed Central

    2012-01-01

    Mechanisms for cellular uptake of nanoparticles have important implications for nanoparticulate drug delivery and toxicity. We have explored the mechanism of uptake of amorphous silica nanoparticles of 14 nm diameter, which agglomerate in culture medium to hydrodynamic diameters around 500 nm. In HT29, HaCat and A549 cells, cytotoxicity was observed at nanoparticle concentrations ≥ 1 μg/ml, but DNA damage was evident at 0.1 μg/ml and above. Transmission electron microscopy (TEM) combined with energy-dispersive X-ray spectroscopy confirmed entry of the silica particles into A549 cells exposed to 10 μg/ml of nanoparticles. The particles were observed in the cytoplasm but not within membrane bound vesicles or in the nucleus. TEM of cells exposed to nanoparticles at 4°C for 30 minutes showed particles enter cells when activity is low, suggesting a passive mode of entry. Plasma lipid membrane models identified physical interactions between the membrane and the silica NPs. Quartz crystal microbalance experiments on tethered bilayer lipid membrane systems show that the nanoparticles strongly bind to lipid membranes, forming an adherent monolayer on the membrane. Leakage assays on large unilamellar vesicles (400 nm diameter) indicate that binding of the silica NPs transiently disrupts the vesicles which rapidly self-seal. We suggest that an adhesive interaction between silica nanoparticles and lipid membranes could cause passive cellular uptake of the particles. PMID:22823932

  16. TOXICITY OF AMORPHOUS SILICA NANOPARTICLES IN MOUSE KERATINOCYTES

    SciTech Connect

    Yu, Kyung; Wang, Wei; Gu, Baohua; Hussain, Saber

    2009-01-01

    The present study was designed to examine the uptake, localization and the cytotoxic effects of well-dispersed amorphous silica nanoparticles in mouse keratinocytes (HEL-30). Mouse keratinocytes were exposed for 24h to various concentrations of amorphous silica nanoparticles in homogeneous suspensions of average size distribution (30, 48, 118 and 535 nm SiO2) then assessed for uptake and biochemical changes. Results of transmission electron microscopy revealed all sizes of silica were taken up into the cells and localized into the cytoplasm. The lactate dehydrogenase (LDH) assay shows LDH leakage was dose- and size-dependent with exposure to 30 and 48 nm nanoparticles. However, no LDH leakage was observed for either 118 or 535 nm nanoparticles. The mitochondrial viability assay (MTT) showed significant toxicity for 30 and 48 nm at high concentrations (100 g/mL) compare to the 118 and 535 nm particles. Further studies were carried out to investigate if cellular reduced GSH and mitochondria membrane potential are involved in the mechanism of SiO2 toxicity. The redox potential of cells (GSH) was reduced significantly at concentrations of 50, 100 and 200 g/mL at 30 nm nanoparticle exposures. However, silica nanoparticles larger than 30 nm showed no changes in GSH levels. Reactive oxygen species (ROS) formation did not show any significant change between controls and the exposed cells. In summary, amorphous silica nanoparticles below 100 nm induced cytotoxicity suggest size-of the particles is critical to produce biological effects.

  17. Carbogenically coated silica nanoparticles and their forensic applications.

    PubMed

    Fernandes, D; Krysmann, M J; Kelarakis, A

    2016-07-01

    Carbogenically coated silica nanoparticles (C-SiO2) exhibit color-tunability and carry great promise for two important forensic applications. First, the C-SiO2 nanopowders are ideal for fingerprint development, yielding strong contrast against multicoloured and patterned backgrounds. Second, spontaneous nanoparticle aggregation leads to non-duplicable, inexpensive nanotags that can support sustainable technologies to combat counterfeiting. PMID:27294695

  18. Studying the interaction between silica nanoparticles and metals by spectrophotometry

    NASA Astrophysics Data System (ADS)

    Revina, A. A.; Potapov, V. V.; Baranova, E. K.; Smirnov, Yu. V.

    2013-02-01

    The optical absorption spectra of water silica sols containing nanoparticles (NPs) of metals (Ag, Pd, Fe, and Pt) are investigated. Silica sols are obtained from natural hydrothermal solutions via membrane concentration (ultrafiltration). Water sols of silica with specific sizes, pH values, ζ potentials of SiO2 NP surfaces, and low concentrations of SiO2 NPs are used. Plasmon resonance in optical absorption spectra is used to study the interaction between silica and metal NPs. Parameters of plasmon resonance (position, height, and half-width of optical absorption bands), from which the degree of interaction is assessed, are determined. Relationships between the optical properties of the surfaces of nanoparticle-size silica particles, the method of their production, and the effect of adsorbed metal particles on these properties are established.

  19. NIR fluorescent silica nanoparticles as reporting labels in bioanalytical applications

    NASA Astrophysics Data System (ADS)

    Patonay, Gabor; Henary, Maged; Chapman, Gala; Emer, Kyle; Crow, Sydney

    2015-03-01

    The use of the NIR spectral region (650-900 nm) for bioanalytical and biomedical analyses is advantageous due to the inherently lower background interference in biological matrices and the high molar absorptivities of NIR chromophores. There are several different groups of NIR fluorescing dye are available for bioanalytical applications. One of these groups, NIR carbocyanines are increasingly used in analytical, bioanalytical and medical applications. These dyes can be used as reporter labels for sensitive bioanalytical use, such as immunochemistry. Due to the spectroscopic sensitivity of NIR carbocyanines for polarity changes in the microenvironment fluorescence quantum yield can vary significantly dependent on the microenvironment. NIR dyes can have relatively low fluorescent quantum yields as compared to visible fluorophores, especially in aqueous buffers but the lower quantum yield is compensated for by a much higher molar absorptivity. The fluorescence intensity of NIR reporting labels can significantly be increased by enclosing several dye molecules in silica nanoparticles. Incorporation of NIR dyes in silica nanoparticles creates a unique challenge as these dyes can be unstable under certain chemical conditions present during silica nanoparticles syntheses. In addition, self quenching may also become a problem for carbocyanines at higher a concentrations that typically found inside of NIR dye loaded silica nanoparticles. Dyes possessing high Stokes' shift can significantly reduce this problem. NIR carbocyanines are uniquely positioned for achieving this goal using a synthetic route that substitutes meso position halogens in NIR fluorescent carbocyanines with a linker containing amino moiety, which can also serve as a linker for covalently attaching the dye molecule to the nanoparticle backbone. The resulting silica nanoparticles can contain a large number of NIR dyes dependent on their size. For example some NIR fluorescent silica nanoparticle labels

  20. Protein adsorption enhanced radio-frequency heating of silica nanoparticles

    PubMed Central

    Wosik, Jarek; Pande, Rohit; Xie, Leiming; Ketharnath, Dhivya; Srinivasan, Srimeenakshi; Godin, Biana

    2013-01-01

    Measurements of specific-absorption-rate (SAR) of silica 30, 50, and 100 nm nanoparticles (NP) suspended in water were carried out at 30 MHz in 7 kV/m radio-frequency (rf) electric field. Size dependent, NP-suspension interface related heating of silica NP was observed. To investigate a possible mechanism of heating, bovine serum albumin was adsorbed on the surface of silica NPs in suspension. It resulted in significant enhancement of SAR when compared to bare silica NPs. A calorimetric and rf loss model was used to calculate effective conductivity of silica NP with/without adsorbed albumin as a function of silica size and albumin concentration. PMID:23964135

  1. Surfactant-free small Ni nanoparticles trapped on silica nanoparticles prepared by pulsed laser ablation in liquid

    NASA Astrophysics Data System (ADS)

    Mafuné, Fumitaka; Okamoto, Takumi; Ito, Miho

    2014-01-01

    Small Ni nanoparticles supported on silica nanoparticles were formed by pulsed laser ablation in liquid. Water dispersing surfactant-free silica particles was used here as a solvent, and a bulk Ni metal plate as a target. The nanoparticles formed by laser ablation in water were readily stabilized by the silica particles, whereas Ni nanoparticles prepared in water without silica were found to be precipitated a few hours after aggregation into 5-30 nm particles. The nanoparticles were characterized by TEM, dark-field STEM and optical absorption spectroscopy, which indicated that small 1-3 nm Ni nanoparticles were adsorbed on the surface of silica.

  2. Surface treatment of silica nanoparticles for stable and charge-controlled colloidal silica

    PubMed Central

    Kim, Kyoung-Min; Kim, Hye Min; Lee, Won-Jae; Lee, Chang-Woo; Kim, Tae-il; Lee, Jong-Kwon; Jeong, Jayoung; Paek, Seung-Min; Oh, Jae-Min

    2014-01-01

    An attempt was made to control the surface charge of colloidal silica nanoparticles with 20 nm and 100 nm diameters. Untreated silica nanoparticles were determined to be highly negatively charged and have stable hydrodynamic sizes in a wide pH range. To change the surface to a positively charged form, various coating agents, such as amine containing molecules, multivalent metal cation, or amino acids, were used to treat the colloidal silica nanoparticles. Molecules with chelating amine sites were determined to have high affinity with the silica surface to make agglomerations or gel-like networks. Amino acid coatings resulted in relatively stable silica colloids with a modified surface charge. Three amino acid moiety coatings (L-serine, L-histidine, and L-arginine) exhibited surface charge modifying efficacy of L-histidine > L-arginine > L-serine and hydrodynamic size preservation efficacy of L-serine > L-arginine > L-histidine. The time dependent change in L-arginine coated colloidal silica was investigated by measuring the pattern of the backscattered light in a Turbiscan™. The results indicated that both the 20 nm and 100 nm L-arginine coated silica samples were fairly stable in terms of colloidal homogeneity, showing only slight coalescence and sedimentation. PMID:25565824

  3. Synthesis of internally functionalized silica nanoparticles for theranostic applications

    NASA Astrophysics Data System (ADS)

    Walton, Nathan Isaac

    This thesis addresses the synthesis and characterization of novel inorganic silica nanoparticle hybrids. It focuses in large part on their potential applications in the medical field. Silica acts as a useful carrier for a variety of compounds and this thesis silica will demonstrate its use as a carrier for boron or gadolinium. Boron-10 and gadolinium-157 have been suggested for the radiological treatment of tumor cells through the process called neutron capture therapy (NCT). Gadolinium is also commonly used as a Magnetic Resonance Imaging (MRI) contrast agent. Particles that carry it have potential theranostic applications of both imaging and treating tumors. Chapter 1 presents a background on synthetic strategies and usages of silica nanoparticles, and NCT theory. Chapter 2 describes a procedure to create mesoporous metal chelating silica nanoparticles, mDTTA. This is achieved via a co-condensation of tetraethoxysilane (TEOS) and 3-trimethoxysilyl-propyl diethylenetriamine (SiDETA) followed by a post-synthesis modification step with bromoacetic acid (BrAA). These particles have a large surface area and well-defined pores of ~2 nm. The mDTTA nanoparticles were used to chelate the copper(II), cobalt(II) and gadolinium(III). The chelating of gadolinium is the most interesting since it can be used as a MRI contrast agent and a neutron capture therapeutic. The synthetic procedure developed also allows for the attachment of a fluorophore that gives the gadolinium chelating mDTTA nanoparticles a dual imaging modality. Chapter 3 presents the synthetic method used to produce two classes of large surface area organically modified silica (ORMOSIL) nanoparticles. Condensating the organosilane vinyltrimethoxysilane in a micellar solution results in nanoparticles that are either surface rough (raspberry-like) or mesoporous nanoparticles, which prior to this thesis has not been demonstrated in ORMOSIL chemistry. Furthermore, the vinyl functionalities are modified, using

  4. Multifunctional clickable and protein-repellent magnetic silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Estupiñán, Diego; Bannwarth, Markus B.; Mylon, Steven E.; Landfester, Katharina; Muñoz-Espí, Rafael; Crespy, Daniel

    2016-01-01

    Silica nanoparticles are versatile materials whose physicochemical surface properties can be precisely adjusted. Because it is possible to combine several functionalities in a single carrier, silica-based materials are excellent candidates for biomedical applications. However, the functionality of the nanoparticles can get lost upon exposure to biological media due to uncontrolled biomolecule adsorption. Therefore, it is important to develop strategies that reduce non-specific protein-particle interactions without losing the introduced surface functionality. Herein, organosilane chemistry is employed to produce magnetic silica nanoparticles bearing differing amounts of amino and alkene functional groups on their surface as orthogonally addressable chemical functionalities. Simultaneously, a short-chain zwitterion is added to decrease the non-specific adsorption of biomolecules on the nanoparticles surface. The multifunctional particles display reduced protein adsorption after incubation in undiluted fetal bovine serum as well as in single protein solutions (serum albumin and lysozyme). Besides, the particles retain their capacity to selectively react with biomolecules. Thus, they can be covalently bio-functionalized with an antibody by means of orthogonal click reactions. These features make the described multifunctional silica nanoparticles a promising system for the study of surface interactions with biomolecules, targeting, and bio-sensing.Silica nanoparticles are versatile materials whose physicochemical surface properties can be precisely adjusted. Because it is possible to combine several functionalities in a single carrier, silica-based materials are excellent candidates for biomedical applications. However, the functionality of the nanoparticles can get lost upon exposure to biological media due to uncontrolled biomolecule adsorption. Therefore, it is important to develop strategies that reduce non-specific protein-particle interactions without losing the

  5. Silica-based mesoporous nanoparticles for controlled drug delivery.

    PubMed

    Kwon, Sooyeon; Singh, Rajendra K; Perez, Roman A; Abou Neel, Ensanya A; Kim, Hae-Won; Chrzanowski, Wojciech

    2013-01-01

    Drug molecules with lack of specificity and solubility lead patients to take high doses of the drug to achieve sufficient therapeutic effects. This is a leading cause of adverse drug reactions, particularly for drugs with narrow therapeutic window or cytotoxic chemotherapeutics. To address these problems, there are various functional biocompatible drug carriers available in the market, which can deliver therapeutic agents to the target site in a controlled manner. Among the carriers developed thus far, mesoporous materials emerged as a promising candidate that can deliver a variety of drug molecules in a controllable and sustainable manner. In particular, mesoporous silica nanoparticles are widely used as a delivery reagent because silica possesses favourable chemical properties, thermal stability and biocompatibility. Currently, sol-gel-derived mesoporous silica nanoparticles in soft conditions are of main interest due to simplicity in production and modification and the capacity to maintain function of bioactive agents. The unique mesoporous structure of silica facilitates effective loading of drugs and their subsequent controlled release. The properties of mesopores, including pore size and porosity as well as the surface properties, can be altered depending on additives used to fabricate mesoporous silica nanoparticles. Active surface enables functionalisation to modify surface properties and link therapeutic molecules. The tuneable mesopore structure and modifiable surface of mesoporous silica nanoparticle allow incorporation of various classes of drug molecules and controlled delivery to the target sites. This review aims to present the state of knowledge of currently available drug delivery system and identify properties of an ideal drug carrier for specific application, focusing on mesoporous silica nanoparticles. PMID:24020012

  6. Silica-based mesoporous nanoparticles for controlled drug delivery

    PubMed Central

    Kwon, Sooyeon; Singh, Rajendra K; Perez, Roman A; Abou Neel, Ensanya A

    2013-01-01

    Drug molecules with lack of specificity and solubility lead patients to take high doses of the drug to achieve sufficient therapeutic effects. This is a leading cause of adverse drug reactions, particularly for drugs with narrow therapeutic window or cytotoxic chemotherapeutics. To address these problems, there are various functional biocompatible drug carriers available in the market, which can deliver therapeutic agents to the target site in a controlled manner. Among the carriers developed thus far, mesoporous materials emerged as a promising candidate that can deliver a variety of drug molecules in a controllable and sustainable manner. In particular, mesoporous silica nanoparticles are widely used as a delivery reagent because silica possesses favourable chemical properties, thermal stability and biocompatibility. Currently, sol-gel-derived mesoporous silica nanoparticles in soft conditions are of main interest due to simplicity in production and modification and the capacity to maintain function of bioactive agents. The unique mesoporous structure of silica facilitates effective loading of drugs and their subsequent controlled release. The properties of mesopores, including pore size and porosity as well as the surface properties, can be altered depending on additives used to fabricate mesoporous silica nanoparticles. Active surface enables functionalisation to modify surface properties and link therapeutic molecules. The tuneable mesopore structure and modifiable surface of mesoporous silica nanoparticle allow incorporation of various classes of drug molecules and controlled delivery to the target sites. This review aims to present the state of knowledge of currently available drug delivery system and identify properties of an ideal drug carrier for specific application, focusing on mesoporous silica nanoparticles. PMID:24020012

  7. Incorporation of Ln-Doped LaPO4 Nanocrystals as Luminescent Markers in Silica Nanoparticles

    NASA Astrophysics Data System (ADS)

    van Hest, Jacobine J. H. A.; Blab, Gerhard A.; Gerritsen, Hans C.; Donega, Celso de Mello; Meijerink, Andries

    2016-05-01

    Lanthanide ions are promising for the labeling of silica nanoparticles with a specific luminescent fingerprint due to their sharp line emission at characteristic wavelengths. With the increasing use of silica nanoparticles in consumer products, it is important to label silica nanoparticles in order to trace the biodistribution, both in the environment and living organisms.

  8. Controlling stability of gold nanoparticles in mesoporous silica

    NASA Astrophysics Data System (ADS)

    Bore, Mangesh Tukaram

    Metal particles deposited on oxide supports are used extensively as heterogeneous catalysts. By using a suitable combination of active metal phases and supports, the catalysts are designed for high activity, selectivity and mechanical strength. However, catalysts undergo deactivation, with poisoning, fouling, sintering and volatilization being some of the common reasons for loss of catalyst activity. For supported metal catalysts, sintering of metal particles is a major cause of catalyst deactivation. The rate and extent of sintering of supported metals depends upon temperature, atmosphere, support, promoter and metal. It is known that gold nanoparticles show high reactivity for CO oxidation at low temperature, but only when the Au particles are very small (<5 nm). Gold nanoparticles supported on silica show rapid sintering at 200°C--400°C. Porosity of support could play an important role in controlling the sintering of metal particles. But the role of pore size, pore curvature and structure is difficult to study with conventional supported metal catalysts. Surfactant templated mesoporous silica is a promising support material since it provides well defined pores of uniform size and structure. Hence, these silica supports provide ideal model systems for control of nanoparticle sintering. Limitations of mesoporous silica are its low hydrothermal stability at elevated temperatures and its inert nature. The pores of mesoporous silica reportedly collapse at temperatures above 500°C and gold nanoparticles supported on reducible oxides such as TiO2, CO3O4 and Fe2O 3 are more active compared to pure silica for CO oxidation. In this work highly dispersed gold nanoparticles (<2 nm) were prepared within the pores of silica with pore sizes ranging from 2.2 nm to 6.5 nm and differing pore architecture (2D-hexagonal, 3D-hexagonal, cubic and pores coiled-up in spherical geometry). In the 2D-hexagonal pore structure, the pores are one dimensional and terminate on the particle

  9. Direct formation of S-nitroso silica nanoparticles from a single silica source.

    PubMed

    Chou, Hung-Chang; Chiu, Shih-Jiuan; Liu, Ying-Ling; Hu, Teh-Min

    2014-01-28

    Nitric oxide (NO) is a ubiquitous molecule in the body. Because of its multiple pathophysiologic roles, the potential for treating various diseases by the exogenous administration of NO has been under intensive investigation. However, the unstable, radical nature of NO poses a major challenge to the effective delivery of NO. Previously, silica nanoparticles synthesized by the traditional method have been developed into NO-carrying systems. In the present study, for the first time NO-carrying silica nanoparticles were prepared from a single silica precursor using a simple nanoprecipitation method. (3-Mercaptopropyl)-trimethoxysilane (MPTMS) was used as the sole silane source, which was subjected to acid-catalyzed S-nitrosation and condensation reactions in a one-pot organic phase. S-Nitroso silica nanoparticles (SNO-SiNPs) were then produced by injecting a smaller quantity of the organic phase into a larger amount of water without surfactants. Various preparation parameters were tested to obtain optimized conditions. Moreover, a phase diagram demonstrating the ouzo effect was constructed. The prepared SNO-SiNPs were spherical particles with a tunable size in the range of 100-400 nm. The nanoparticles in aqueous dispersions exhibited high colloid stability, possibly resulting from highly negatively charged surfaces. The result of solid-state (29)Si NMR shows the predominance of T(2) and T(3) silicon structures, suggesting that nanoparticles were formed from polycondensed silica species. In conclusion, NO-loaded silica nanoparticles have been directly prepared from a single silane precursor using a surfactant-free, low-energy, one-step nanoprecipitation approach. The method precludes the need for the initial formation of bare particles and subsequent functionalization steps. PMID:24410024

  10. Silicalites and Mesoporous Silica Nanoparticles for photodynamic therapy.

    PubMed

    Hocine, Ouahiba; Gary-Bobo, Magali; Brevet, David; Maynadier, Marie; Fontanel, Simon; Raehm, Laurence; Richeter, Sébastien; Loock, Bernard; Couleaud, Pierre; Frochot, Céline; Charnay, Clarence; Derrien, Gaëlle; Smaïhi, Monique; Sahmoune, Amar; Morère, Alain; Maillard, Philippe; Garcia, Marcel; Durand, Jean-Olivier

    2010-12-15

    The synthesis of silicalites and Mesoporous Silica Nanoparticles (MSN), which covalently incorporate original water-soluble photosensitizers for PDT applications is described. PDT was performed on MDA-MB-231 breast cancer cells. All the nanoparticles showed significant cell death after irradiation, which was not correlated with (1)O(2) quantum yield of the nanoparticles. Other parameters are involved and in particular the surface and shape of the nanoparticles which influence the pathway of endocytosis. Functionalization with mannose was necessary to obtain the best results with PDT due to an active endocytosis of mannose-functionalized nanoparticles. The quantity of mannose on the surface should be carefully adjusted as a too high amount of mannose impairs the phototoxicity of the nanoparticles. Fluorescein was also encapsulated in MCM-41 type MSN in order to localize the nanoparticles in the organelles of the cells by confocal microscopy. The MSN were localized in lysosomes after active endocytosis by mannose receptors. PMID:20934496

  11. Mesoporous silica nanoparticles deliver DNA and chemicals into plants

    NASA Astrophysics Data System (ADS)

    Torney, François; Trewyn, Brian G.; Lin, Victor S.-Y.; Wang, Kan

    2007-05-01

    Surface-functionalized silica nanoparticles can deliver DNA and drugs into animal cells and tissues. However, their use in plants is limited by the cell wall present in plant cells. Here we show a honeycomb mesoporous silica nanoparticle (MSN) system with 3-nm pores that can transport DNA and chemicals into isolated plant cells and intact leaves. We loaded the MSN with the gene and its chemical inducer and capped the ends with gold nanoparticles to keep the molecules from leaching out. Uncapping the gold nanoparticles released the chemicals and triggered gene expression in the plants under controlled-release conditions. Further developments such as pore enlargement and multifunctionalization of these MSNs may offer new possibilities in target-specific delivery of proteins, nucleotides and chemicals in plant biotechnology.

  12. Acetylcholinesterase immobilized onto PEI-coated silica nanoparticles.

    PubMed

    Tumturk, Hayrettin; Yüksekdag, Hazer

    2016-01-01

    Polyethyleneimine (PEI) coated-silica nanoparticles were prepared by the Stöber method. The formation and the structure of the nanoparticles were characterized by ATR-FT-IR spectroscopy and transmission electron microscopy (TEM). TEM images of the silica and PEI-coated nanoparticles revealed that they were well dispersed and that there was no agglomeration. The acetylcholineesterase enzyme was immobilized onto these nanoparticles. The effects of pH and temperature on the storage stability of the free and immobilized enzyme were investigated. The optimum pHs for free and immobilized enzymes were determined as 7.0 and 8.0, respectively. The optimum temperatures for free and immobilized enzymes were found to be 30.0 and 35.0°C, respectively. The maximum reaction rate (Vmax) and the Michaelis-Menten constant (Km) were investigated for the free and immobilized enzyme. The storage stability of acetylcholinesterase was increased when immobilized onto the novel PEI-coated silica nanoparticles. The reuse numbers of immobilized enzyme were also studied. These hybrid nanoparticles are desirable as carriers for biomedical applications. PMID:25365355

  13. Interaction of surface-modified silica nanoparticles with clay minerals

    NASA Astrophysics Data System (ADS)

    Omurlu, Cigdem; Pham, H.; Nguyen, Q. P.

    2016-05-01

    In this study, the adsorption of 5-nm silica nanoparticles onto montmorillonite and illite is investigated. The effect of surface functionalization was evaluated for four different surfaces: unmodified, surface-modified with anionic (sulfonate), cationic (quaternary ammonium (quat)), and nonionic (polyethylene glycol (PEG)) surfactant. We employed ultraviolet-visible spectroscopy to determine the concentration of adsorbed nanoparticles in conditions that are likely to be found in subsurface reservoir environments. PEG-coated and quat/PEG-coated silica nanoparticles were found to significantly adsorb onto the clay surfaces, and the effects of electrolyte type (NaCl, KCl) and concentration, nanoparticle concentration, pH, temperature, and clay type on PEG-coated nanoparticle adsorption were studied. The type and concentration of electrolytes were found to influence the degree of adsorption, suggesting a relationship between the interlayer spacing of the clay and the adsorption ability of the nanoparticles. Under the experimental conditions reported in this paper, the isotherms for nanoparticle adsorption onto montmorillonite at 25 °C indicate that adsorption occurs less readily as the nanoparticle concentration increases.

  14. Hierarchical mesoporous silica nanoparticles as superb light scattering materials.

    PubMed

    Ryu, Jaehoon; Yun, Juyoung; Lee, Jungsup; Lee, Kisu; Jang, Jyongsik

    2016-02-01

    A novel approach to enhance the light scattering effect was explored by applying hierarchical silica nanoparticles in DSSCs as scattering layers. The WSN-incorporated cells showed a PCE value of 9.53% and a PCE enhancement of 30.19% compared with those of the reference cells. PMID:26699659

  15. Synthesis of Ag@Silica Nanoparticles by Assisted Laser Ablation

    NASA Astrophysics Data System (ADS)

    González-Castillo, Jr.; Rodriguez, E.; Jimenez-Villar, E.; Rodríguez, D.; Salomon-García, I.; de Sá, Gilberto F.; García-Fernández, T.; Almeida, DB; Cesar, CL; Johnes, R.; Ibarra, Juana C.

    2015-10-01

    This paper reports the synthesis of silver nanoparticles coated with porous silica (Ag@Silica NPs) using an assisted laser ablation method. This method is a chemical synthesis where one of the reagents (the reducer agent) is introduced in nanometer form by laser ablation of a solid target submerged in an aqueous solution. In a first step, a silicon wafer immersed in water solution was laser ablated for several minutes. Subsequently, an AgNO3 aliquot was added to the aqueous solution. The redox reaction between the silver ions and ablation products leads to a colloidal suspension of core-shell Ag@Silica NPs. The influence of the laser pulse energy, laser wavelength, ablation time, and Ag+ concentration on the size and optical properties of the Ag@Silica NPs was investigated. Furthermore, the colloidal suspensions were studied by UV-VIS-NIR spectroscopy, X-Ray diffraction, and high-resolution transmission electron microscopy (HRTEM).

  16. Synthesis of Ag@Silica Nanoparticles by Assisted Laser Ablation.

    PubMed

    González-Castillo, J R; Rodriguez, E; Jimenez-Villar, E; Rodríguez, D; Salomon-García, I; de Sá, Gilberto F; García-Fernández, T; Almeida, D B; Cesar, C L; Johnes, R; Ibarra, Juana C

    2015-12-01

    This paper reports the synthesis of silver nanoparticles coated with porous silica (Ag@Silica NPs) using an assisted laser ablation method. This method is a chemical synthesis where one of the reagents (the reducer agent) is introduced in nanometer form by laser ablation of a solid target submerged in an aqueous solution. In a first step, a silicon wafer immersed in water solution was laser ablated for several minutes. Subsequently, an AgNO3 aliquot was added to the aqueous solution. The redox reaction between the silver ions and ablation products leads to a colloidal suspension of core-shell Ag@Silica NPs. The influence of the laser pulse energy, laser wavelength, ablation time, and Ag(+) concentration on the size and optical properties of the Ag@Silica NPs was investigated. Furthermore, the colloidal suspensions were studied by UV-VIS-NIR spectroscopy, X-Ray diffraction, and high-resolution transmission electron microscopy (HRTEM). PMID:26464175

  17. Fluorescent silica nanoparticles containing covalently bound dyes for reporter, marker, and sensor applications

    NASA Astrophysics Data System (ADS)

    Patonay, Gabor; Henary, Maged; Chapman, Gala; Emer, Kyle; Crow, Sidney

    2016-03-01

    Silica nanoparticles have proven to be useful in many bioanalytical and medical applications and have been used in numerous applications during the last decade. Combining the properties of silica nanoparticles and fluorescent dyes that may be used as chemical probes or labels can be relatively easy by simply soaking porous silica nanoparticles in a solution of the dye of interest. Under proper conditions the entrapped dye can stay inside the silica nanoparticle for several hours resulting in a useful probe. In spite of the relative durability of these probes, leaching can still occur. A much better approach is to synthesize silica nanoparticles that have the fluorescent dye covalently attached to the backbone structure of the silica nanoparticle. This can be achieved by using appropriately modified tetraethyl orthosilicate (TEOS) analogues during the silica nanoparticle synthesis. The molar ratio of TEOS and modified TEOS will determine the fluorescent dye load in the silica nanoparticle. Dependent on the chemical stability of the reporting dye either reverse micellar (RM) or Stöber method can be used for silica nanoparticle synthesis. If dye stability allows RM procedure is preferred as it results in a much easier control of the silica nanoparticle reaction itself. Also controlling the size and uniformity of the silica nanoparticles are much easier using RM method. Dependent on the functional groups present in the reporting dye used in preparation of the modified TEOS, the silica nanoparticles can be utilized in many applications such as pH sensor, metal ion sensors, labels, etc. In addition surface activated silica nanoparticles with reactive moieties are also excellent reporters or they can be used as bright fluorescent labels. Many different fluorescent dyes can be used to synthesize silica nanoparticles including visible and NIR dyes. Several bioanalytical applications are discussed including studying amoeba phagocytosis.

  18. Enhanced stab resistance of armor composites with functionalized silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Mahfuz, Hassan; Clements, Floria; Rangari, Vijaya; Dhanak, Vinod; Beamson, Graham

    2009-03-01

    Traditionally shear thickening fluid (STF) reinforced with Kevlar has been used to develop flexible armor. At the core of the STF-Kevlar composites is a mixture of polyethylene glycol (PEG) and silica particles. This mixture is often known as STF and is consisted of approximately 45 wt % PEG and 55 wt % silica. During rheological tests, STF shows instantaneous spike in viscosity above a critical shear rate. Fabrication of STF-Kevlar composites requires preparation of STF, dilution with ethanol, and then impregnation with Kevlar. In the current approach, nanoscale silica particles were dispersed directly into a mixture of PEG and ethanol through a sonic cavitation process. Two types of silica nanoparticles were used in the investigation: 30 nm crystalline silica and 7 nm amorphous silica. The admixture was then reinforced with Kevlar fabric to produce flexible armor composites. In the next step, silica particles are functionalized with a silane coupling agent to enhance bonding between silica and PEG. The performance of the resulting armor composites improved significantly. As evidenced by National Institute of Justice spike tests, the energy required for zero-layer penetration (i.e., no penetration) jumped twofold: from 12 to 25 J cm2/g. The source of this improvement has been traced to the formation of siloxane (Si-O-Si) bonds between silica and PEG and superior coating of Kevlar filaments with particles. Fourier transform infrared, x-ray photoemission spectroscopy, and scanning electron microscopy studies were performed to examine chemical bonds, elemental composition, and particle dispersion responsible for such improvement. In summary, our experiments have demonstrated that functionalization of silica particles followed by direct dispersion into PEG resulted in superior Kevlar composites having much higher spike resistance.

  19. Non-seeded synthesis and characterization of superparamagnetic iron oxide nanoparticles incorporated into silica nanoparticles via ultrasound.

    PubMed

    Sodipo, Bashiru Kayode; Abdul Aziz, Azlan

    2015-03-01

    A non-seeded method of incorporating superparamagnetic iron oxide nanoparticles (SPION) into silica nanoparticles is presented. Mixture of both SPION and silica nanoparticles was ultrasonically irradiated. The collapsed bubbles and shockwave generated from the ultrasonic irradiation produce tremendous force that caused inelastic collision and incorporation of SPION into the silica. Physicochemical analyses using transmission electron microscope (TEM), electronic spectroscopic imaging (ESI), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy demonstrated the formation of SPION/silica composite nanoparticles. The prepared composite nanoparticles exhibited superparamagnetic behaviour and nearly 70% of the initial saturation magnetization (Ms) of the SPION was retained. The presence and reactivity of the silica were demonstrated via assembling decanethiol monolayer on the composite nanoparticles. The silanol group of the silica provided the binding site for the alkyl group in the decanethiol molecules. Therefore, the thiol moiety became the terminal and functional group on the magnetic composite nanoparticles. PMID:25315418

  20. Dye-doped silica-based nanoparticles for bioapplications

    NASA Astrophysics Data System (ADS)

    Nhung Tran, Hong; Nghiem, Thi Ha Lien; Thuy Duong Vu, Thi; Tan Pham, Minh; Van Nguyen, Thi; Trang Tran, Thu; Chu, Viet Ha; Thuan Tong, Kim; Thuy Tran, Thanh; Le, Thi Thanh Xuan; Brochon, Jean-Claude; Quy Nguyen, Thi; Nhung Hoang, My; Nguyen Duong, Cao; Thuy Nguyen, Thi; Hoang, Anh Tuan; Hoa Nguyen, Phuong

    2013-12-01

    This paper presents our recent research results on synthesis and bioapplications of dye-doped silica-based nanoparticles. The dye-doped water soluble organically modified silicate (ORMOSIL) nanoparticles (NPs) with the size of 15-100 nm were synthesized by modified Stöber method from methyltriethoxysilane CH3Si(OCH3)3 precursor (MTEOS). Because thousands of fluorescent dye molecules are encapsulated in the silica-based matrix, the dye-doped nanoparticles are extremely bright and photostable. Their surfaces were modified with bovine serum albumin (BSA) and biocompatible chemical reagents. The highly intensive luminescent nanoparticles were combined with specific bacterial and breast cancer antigen antibodies. The antibody-conjugated nanoparticles can identify a variety of bacterium, such as Escherichia coli O157:H7, through antibody-antigen interaction and recognition. A highly sensitive breast cancer cell detection has been achieved with the anti-HER2 monoclonal antibody-nanoparticles complex. These results demonstrate the potential to apply these fluorescent nanoparticles in various biodetection systems.

  1. Chromogenic Detection of Aqueous Formaldehyde Using Functionalized Silica Nanoparticles.

    PubMed

    El Sayed, Sameh; Pascual, Lluı́s; Licchelli, Maurizio; Martínez-Máñez, Ramón; Gil, Salvador; Costero, Ana M; Sancenón, Félix

    2016-06-15

    Silica nanoparticles functionalized with thiol reactive units and bulky polar polyamines were used for the selective colorimetric detection of formaldehyde. The reaction of thiols groups in the nanoparticles surface with a squaraine dye resulted in loss of the π-conjugation of the chromophores, and the subsequent bleaching of the solution. However, when formaldehyde was present in the suspension, the thiol-squaraine reaction was inhibited and a chromogenic response was observed. A selective response to formaldehyde was observed only when the thiol and polyamine groups were anchored to the silica surface. The observed selective response was ascribed to the fact that bulky polyamines generate a highly polar environment around thiols, which were only able to react with the small and polar formaldehyde, but not with other aldehydes. The sensing nanoparticles showed a limit of detection (LOD) for formaldehyde of 36 ppb in water. PMID:27250594

  2. Thrombin-Responsive Gated Silica Mesoporous Nanoparticles As Coagulation Regulators.

    PubMed

    Bhat, Ravishankar; Ribes, Àngela; Mas, Núria; Aznar, Elena; Sancenón, Félix; Marcos, M Dolores; Murguía, Jose R; Venkataraman, Abbaraju; Martínez-Máñez, Ramón

    2016-02-01

    The possibility of achieving sophisticated actions in complex biological environments using gated nanoparticles is an exciting prospect with much potential. We herein describe new gated mesoporous silica nanoparticles (MSN) loaded with an anticoagulant drug and capped with a peptide containing a thrombin-specific cleavage site. When the coagulation cascade was triggered, active thrombin degraded the capping peptidic sequence and induced the release of anticoagulant drugs to delay the clotting process. The thrombin-dependent response was assessed and a significant increase in coagulation time in plasma from 2.6 min to 5 min was found. This work broadens the application of gated silica nanoparticles and demonstrates their ability to act as controllers in a complex scenario such as hemostasis. PMID:26794474

  3. Diatomite silica nanoparticles for drug delivery

    NASA Astrophysics Data System (ADS)

    Ruggiero, Immacolata; Terracciano, Monica; Martucci, Nicola M.; De Stefano, Luca; Migliaccio, Nunzia; Tatè, Rosarita; Rendina, Ivo; Arcari, Paolo; Lamberti, Annalisa; Rea, Ilaria

    2014-07-01

    Diatomite is a natural fossil material of sedimentary origin, constituted by fragments of diatom siliceous skeletons. In this preliminary work, the properties of diatomite nanoparticles as potential system for the delivery of drugs in cancer cells were exploited. A purification procedure, based on thermal treatments in strong acid solutions, was used to remove inorganic and organic impurities from diatomite and to make them a safe material for medical applications. The micrometric diatomite powder was reduced in nanoparticles by mechanical crushing, sonication, and filtering. Morphological analysis performed by dynamic light scattering and transmission electron microscopy reveals a particles size included between 100 and 300 nm. Diatomite nanoparticles were functionalized by 3-aminopropyltriethoxysilane and labeled by tetramethylrhodamine isothiocyanate. Different concentrations of chemically modified nanoparticles were incubated with cancer cells and confocal microscopy was performed. Imaging analysis showed an efficient cellular uptake and homogeneous distribution of nanoparticles in cytoplasm and nucleus, thus suggesting their potentiality as nanocarriers for drug delivery.

  4. Mesoporous Silica Nanoparticles and Films for Cargo Delivery

    NASA Astrophysics Data System (ADS)

    Guardado Alvarez, Tania Maria

    Mesoporous silica materials are well known materials that can range from films to nanoparticles. Mesoporous silica nanoparticles (MSNs) and mesoporous silica films have been of increasing interest among the scientific community for its use in cargo delivery. Silica provides ease of functionalization, a robust support and biocompatibility. Several methods have been used in order to give the mesoporous silica nanomaterials different qualities that render them a useful material with different characteristics. Among these methods is surface modification by taking advantage of the OH groups on the surface. When a molecule attached to the surface can act as a molecular machine it transforms the nanomaterial to act as delivery system that can be activated upon command. The work covered in this thesis focuses on the development and synthesis of different mesoporous silica materials for the purpose of trapping and releasing cargo molecules. Chapter 2 focuses in the photoactivation of "snap-top" stoppers over the pore openings of mesoporous silica nanoparticles that releases intact cargo molecules from the pores. The on-command release can be stimulated by either one UV photon or two coherent near-IR photons. Two-photon activation is particularly desirable for use in biological systems because it enables good tissue penetration and precise spatial control. Chapter 3 focuses on the design and synthesis of a nano-container consisting of mesoporous silica nanoparticles with the pore openings covered by "snap-top" caps that are opened by near-IR light. A photo transducer molecule that is a reducing agent in an excited electronic state is covalently attached to the system. Near IR two-photon excitation causes intermolecular electron transfer that reduces a disulfide bond holding the cap in place, thus allowing the cargo molecules to escape. The operation of the "snap-top" release mechanism by both one- and two photon is described. This system presents a proof of concept of a near

  5. Interferences of Silica Nanoparticles in Green Fluorescent Protein Folding Processes.

    PubMed

    Klein, Géraldine; Devineau, Stéphanie; Aude, Jean Christophe; Boulard, Yves; Pasquier, Hélène; Labarre, Jean; Pin, Serge; Renault, Jean Philippe

    2016-01-12

    We investigated the relationship between unfolded proteins, silica nanoparticles and chaperonin to determine whether unfolded proteins could stick to silica surfaces and how this process could impair heat shock protein activity. The HSP60 catalyzed green fluorescent protein (GFP) folding was used as a model system. The adsorption isotherms and adsorption kinetics of denatured GFP were measured, showing that denaturation increases GFP affinity for silica surfaces. This affinity is maintained even if the surfaces are covered by a protein corona and allows silica NPs to interfere directly with GFP folding by trapping it in its unstructured state. We determined also the adsorption isotherms of HSP60 and its chaperonin activity once adsorbed, showing that SiO2 NP can interfere also indirectly with protein folding through chaperonin trapping and inhibition. This inhibition is specifically efficient when NPs are covered first with a layer of unfolded proteins. These results highlight for the first time the antichaperonin activity of silica NPs and ask new questions about the toxicity of such misfolded proteins/nanoparticles assembly toward cells. PMID:26649773

  6. Mesoporous silica nanoparticles in target drug delivery system: A review

    PubMed Central

    Bharti, Charu; Nagaich, Upendra; Pal, Ashok Kumar; Gulati, Neha

    2015-01-01

    Due to lack of specification and solubility of drug molecules, patients have to take high doses of the drug to achieve the desired therapeutic effects for the treatment of diseases. To solve these problems, there are various drug carriers present in the pharmaceuticals, which can used to deliver therapeutic agents to the target site in the body. Mesoporous silica materials become known as a promising candidate that can overcome above problems and produce effects in a controllable and sustainable manner. In particular, mesoporous silica nanoparticles (MSNs) are widely used as a delivery reagent because silica possesses favorable chemical properties, thermal stability, and biocompatibility. The unique mesoporous structure of silica facilitates effective loading of drugs and their subsequent controlled release of the target site. The properties of mesoporous, including pore size, high drug loading, and porosity as well as the surface properties, can be altered depending on additives used to prepare MSNs. Active surface enables functionalization to changed surface properties and link therapeutic molecules. They are used as widely in the field of diagnosis, target drug delivery, bio-sensing, cellular uptake, etc., in the bio-medical field. This review aims to present the state of knowledge of silica containing mesoporous nanoparticles and specific application in various biomedical fields. PMID:26258053

  7. Surfactant-free synthesis of mesoporous and hollow silica nanoparticles with an inorganic template.

    PubMed

    Baù, Luca; Bártová, Barbora; Arduini, Maria; Mancin, Fabrizio

    2009-12-28

    A surfactant-free synthesis of mesoporous and hollow silica nanoparticles is reported in which boron acts as the templating agent. Using such a simple and mild procedure as a treatment with water, the boron-rich phase is selectively removed, affording mesoporous pure silica nanoparticles with wormhole-like pores or, depending on the synthetic conditions, silica nanoshells. PMID:20024287

  8. Luminescent Silica Nanoparticles Featuring Collective Processes for Optical Imaging.

    PubMed

    Rampazzo, Enrico; Prodi, Luca; Petrizza, Luca; Zaccheroni, Nelsi

    2016-01-01

    The field of nanoparticles has successfully merged with imaging to optimize contrast agents for many detection techniques. This combination has yielded highly positive results, especially in optical and magnetic imaging, leading to diagnostic methods that are now close to clinical use. Biological sciences have been taking advantage of luminescent labels for many years and the development of luminescent nanoprobes has helped definitively in making the crucial step forward in in vivo applications. To this end, suitable probes should present excitation and emission within the NIR region where tissues have minimal absorbance. Among several nanomaterials engineered with this aim, including noble metal, lanthanide, and carbon nanoparticles and quantum dots, we have focused our attention here on luminescent silica nanoparticles. Many interesting results have already been obtained with nanoparticles containing only one kind of photophysically active moiety. However, the presence of different emitting species in a single nanoparticle can lead to diverse properties including cooperative behaviours. We present here the state of the art in the field of silica luminescent nanoparticles exploiting collective processes to obtain ultra-bright units suitable as contrast agents in optical imaging and optical sensing and for other high sensitivity applications. PMID:26589504

  9. Evaluation of silica nanoparticle binding to major human blood proteins

    NASA Astrophysics Data System (ADS)

    Hata, Katsutomo; Higashisaka, Kazuma; Nagano, Kazuya; Mukai, Yohei; Kamada, Haruhiko; Tsunoda, Shin-ichi; Yoshioka, Yasuo; Tsutsumi, Yasuo

    2014-12-01

    Nanomaterials are used for various biomedical applications because they are often more effective than conventional materials. Recently, however, it has become clear that the protein corona that forms on the surface of nanomaterials when they make contact with biological fluids, such as blood, influences the pharmacokinetics and biological responses induced by the nanomaterials. Therefore, when evaluating nanomaterial safety and efficacy, it is important to analyze the interaction between nanomaterials and proteins in biological fluids and to evaluate the effects of the protein corona. Here, we evaluated the interaction of silica nanoparticles, a commonly used nanomaterial, with the human blood proteins albumin, transferrin, fibrinogen, and IgG. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed that the amount of albumin, transferrin, and IgG binding to the silica particles increased as the particle size decreased under conditions where the silica particle mass remained the same. However, under conditions in which the specific surface area remained constant, there were no differences in the binding of human plasma proteins to the silica particles tested, suggesting that the binding of silica particles with human plasma proteins is dependent on the specific surface area of the silica particles. Furthermore, the amount of albumin, transferrin, and IgG binding to silica nanoparticles with a diameter of 70 nm (nSP70) and a functional amino group was lower than that with unmodified nSP70, although there was no difference in the binding between nSP70 with the surface modification of a carboxyl functional group and nSP70. These results suggest that the characteristics of nanomaterials are important for binding with human blood proteins; this information may contribute to the development of safe and effective nanomaterials.

  10. Magnetic heating of silica-coated manganese ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Iqbal, Yousaf; Bae, Hongsub; Rhee, Ilsu; Hong, Sungwook

    2016-07-01

    Manganese ferrite nanoparticles were synthesized using the reverse micelle method; these particles were then coated with silica. The silica-coated nanoparticles were spherical in shape, with an average diameter of 14 nm. The inverse spinel crystalline structure was observed through X-ray diffraction patterns. The coating status of silica on the surface of the nanoparticles was confirmed with a Fourier transform infrared spectrometer. The superparamagnetic properties were revealed by the zero coercive force in the hysteresis curve. Controllable heating at a fixed temperature of 42 °C was achieved by changing either the concentration of nanoparticles in the aqueous solution or the intensity of the alternating magnetic field. We found that at a fixed field strength of 5.5 kA/m, the 2.6 mg/ml sample showed a saturation temperature of 42 °C for magnetic hyperthermia. On the other hand, at a fixed concentration of 3.6 mg/ml, a field intensity of 4.57 kA/m satisfied the required temperature of 42 °C.

  11. Facile Fabrication of Ultrafine Hollow Silica and Magnetic Hollow Silica Nanoparticles by a Dual-Templating Approach

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Xiao, Xiangheng; Zhang, Shaofeng; Fan, Lixia; Peng, Tangchao; Ren, Feng; Jiang, Changzhong

    2010-01-01

    The development of synthetic process for hollow silica materials is an issue of considerable topical interest. While a number of chemical routes are available and are extensively used, the diameter of hollow silica often large than 50 nm. Here, we report on a facial route to synthesis ultrafine hollow silica nanoparticles (the diameter of ca. 24 nm) with high surface area by using cetyltrimethylammmonium bromide (CTAB) and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as co-templates and subsequent annealing treatment. When the hollow magnetite nanoparticles were introduced into the reaction, the ultrafine magnetic hollow silica nanoparticles with the diameter of ca. 32 nm were obtained correspondingly. Transmission electron microscopy studies confirm that the nanoparticles are composed of amorphous silica and that the majority of them are hollow.

  12. Uniform silica nanoparticles encapsulating two-photon absorbing fluorescent dye

    SciTech Connect

    Wu Weibing; Liu Chang; Wang Mingliang; Huang Wei; Zhou Shengrui; Jiang Wei; Sun Yueming; Cui Yiping; Xu Chunxinag

    2009-04-15

    We have prepared uniform silica nanoparticles (NPs) doped with a two-photon absorbing zwitterionic hemicyanine dye by reverse microemulsion method. Obvious solvatochromism on the absorption spectra of dye-doped NPs indicates that solvents can partly penetrate into the silica matrix and then affect the ground and excited state of dye molecules. For dye-doped NP suspensions, both one-photon and two-photon excited fluorescence are much stronger and recorded at shorter wavelength compared to those of free dye solutions with comparative overall dye concentration. This behavior is possibly attributed to the restricted twisted intramolecular charge transfer (TICT), which reduces fluorescence quenching when dye molecules are trapped in the silica matrix. Images from two-photon laser scanning fluorescence microscopy demonstrate that the dye-doped silica NPs can be actively uptaken by Hela cells with low cytotoxicity. - Graphical abstract: Water-soluble silica NPs doped with a two-photon absorbing zwitterionic hemicyanine dye were prepared. They were found of enhanced one-photon and two-photon excited fluorescence compared to free dye solutions. Images from two-photon laser scanning fluorescence microscopy demonstrate that the dye-doped silica NPs can be actively uptaken by Hela cells.

  13. Effect of silica nanoparticles on microbial biomass and silica availability in maize rhizosphere.

    PubMed

    Rangaraj, Suriyaprabha; Gopalu, Karunakaran; Rathinam, Yuvakkumar; Periasamy, Prabu; Venkatachalam, Rajendran; Narayanasamy, Kannan

    2014-01-01

    The effect of silica nanoparticles and conventional silica sources on the changes in microbial biomass and silica availability to pure soil and maize rhizosphere was studied. Nanosilica (20-40 nm) was synthesized from rice husk and comprehensively characterized. The efficiency of nanosilica was evaluated in terms of its effects on beneficial microbial population such as phosphate solubilizers, nitrogen fixers, silicate solubilizers, microbial biomass carbon and nitrogen content, and silica content in comparison with other silica sources such as microsilica, sodium silicate, and silicic acid. Nanosilica significantly (P < 0.05) enhanced microbial populations, total biomass content (C = 1508 μg g(-1) and N = 178 μg g(-1) ), and silica content (14.75 mg mL(-1) ). Although microsilica sources enhanced factors associated with soil fertility, their use by maize roots and silicification in soil was found to be less. The results show that nanosilica plays a vital role in influencing soil nutrient content and microbial biota and, hence, may promote the growth of maize crop. PMID:24329970

  14. Diatomite silica nanoparticles for drug delivery

    PubMed Central

    2014-01-01

    Diatomite is a natural fossil material of sedimentary origin, constituted by fragments of diatom siliceous skeletons. In this preliminary work, the properties of diatomite nanoparticles as potential system for the delivery of drugs in cancer cells were exploited. A purification procedure, based on thermal treatments in strong acid solutions, was used to remove inorganic and organic impurities from diatomite and to make them a safe material for medical applications. The micrometric diatomite powder was reduced in nanoparticles by mechanical crushing, sonication, and filtering. Morphological analysis performed by dynamic light scattering and transmission electron microscopy reveals a particles size included between 100 and 300 nm. Diatomite nanoparticles were functionalized by 3-aminopropyltriethoxysilane and labeled by tetramethylrhodamine isothiocyanate. Different concentrations of chemically modified nanoparticles were incubated with cancer cells and confocal microscopy was performed. Imaging analysis showed an efficient cellular uptake and homogeneous distribution of nanoparticles in cytoplasm and nucleus, thus suggesting their potentiality as nanocarriers for drug delivery. PACS 87.85.J81.05.Rm; 61.46. + w PMID:25024689

  15. β-ray irradiation effects on silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Alessi, A.; Agnello, S.; Buscarino, G.; Boizot, B.; Cannas, M.; Gelardi, F. M.

    2015-04-01

    By electron paramagnetic resonance (EPR) measurements, we examine the amplitude of the signal typically due to a combination of NBOHC (Non Bridging Hole Center) and POR (Peroxy Radical) defects induced by β-ray irradiation (from 1.2 to 1200 MGy) in silica nanoparticles with diameter ranging from 7 to 20 nm. Our data indicate that the signal line-shapes recorded at different doses is quite independent from the particles sizes and from the dose. Furthermore, for each considered nanoparticles size, the concentration of defects is also almost constant with respect to dose, and it does not change significantly if measured after 2 or 9 months from the irradiation. By contrast, we observed that the concentration of NBOHC+POR decreases on increasing the specific surface, indicating that the content of the defects depends on the nanoparticles size. Such dependence can be explained by a shell model in which the detected defects are located in the inner part of the nanoparticles.

  16. Photothermally responsive gold nanoparticle conjugated polymer-grafted porous hollow silica nanocapsules.

    PubMed

    Paramelle, David; Gorelik, Sergey; Liu, Ye; Kumar, Jatin

    2016-08-01

    Polymer-grafted porous hollow silica nanoparticles prepared by reversible addition-fragmentation chain transfer polymerisation have an upper critical solution temperature of 45 °C. Conjugation of 5 nm gold nanoparticles onto polymer-grafted porous hollow silica nanoparticles enables remarkable specific photothermally-induced controlled release of encapsulated Rhodamine B by laser-stimulation at physiological temperature. PMID:27427407

  17. Silver nanoparticles incorporated onto ordered mesoporous silica from Tollen's reagent

    NASA Astrophysics Data System (ADS)

    Zienkiewicz-Strzałka, M.; Pasieczna-Patkowska, S.; Kozak, M.; Pikus, S.

    2013-02-01

    Noble metal nanostructures supported on mesoporous silica are bridge between traditional silica adsorbents and modern catalysts. In this work the Ag/SBA-15 mesoporous materials were synthesized and characterized. Various forms of nanosilver supported on ordered mesoporous template have been successfully obtained via proposed procedures. In all synthesized materials, Tollen's reagent (diammine silver complex [Ag(NH3)2]+) was used as a silver source. Silver nanoparticles were prepared by reduction of ammoniacal silver complex by formaldehyde in the solution of stabilizer. After reduction, Ag nanoparticles could be deposited on SBA-15, or added during traditional synthesis of SBA-15 giving silver or silver chloride nanoparticles in the combination with porous silica. Silver nanostructures as nanoparticles or nanowires were also embedded onto the SBA-15 by incipient wetness impregnation of silver ions. Absorbed silver ions were next reduced under hydrogen at high temperature. There are many advantages of utilized ammoniacal silver complex as a silver source. Proposed method is capable to synthesis of various metal nanostructures with controlled composition and morphology. The silver ammonia complex is composed of two ions surrounding and protecting the central silver ion, so it is possible to obtain very small nanoparticles using simple approach without any functionalization of external and internal surface of SBA-15. This approach allows obtaining greatly small silver nanoparticles on SBA-15 (4 nm) or nanowires depending on the metal loading amount. Moreover, the colloidal silver solution prepared from Tollen's reagent, in the presence of triblock copolymer, remains stable for a long time. Reduction of Tollen's reagent to silver colloidal solution seems to be efficient, fast and interesting approach for the preparation of supported silver nanostructures Obtained samples were characterized by powder X-ray diffraction, small angle X-ray scattering (SAXS), UV

  18. Silica nanoparticles as vehicles for therapy delivery in neurological injury

    NASA Astrophysics Data System (ADS)

    Schenk, Desiree

    Acrolein, a very reactive aldehyde, is a culprit in the biochemical cascade after primary, mechanical spinal cord injury (SCI), which leads to the destruction of tissue initially unharmed, referred to as "secondary injury". Additionally, in models of multiple sclerosis (MS) and some clinical research, acrolein levels are significantly increased. This aldehyde overwhelms the natural anti-oxidant system, reacts freely with proteins, and releases during lipid peroxidation (LPO), effectively regenerating its self. Due to its ability to make more copies of itself in the presence of tissue via lipid peroxidation, researchers believe that acrolein plays a role in the increased destruction of the central nervous system in both SCI and MS. Hydralazine, an FDA-approved hypertension drug, has been shown to scavenge acrolein, but its side effects and short half life at the appropriate dose for acrolein scavenging must be improved for beneficial clinical translation. Due to the inefficient delivery of therapeutic drugs, nanoparticles have become a major field of exploration for medical applications. Based on their material properties, they can help treat disease by delivering drugs to specific tissues, enhancing detection methods, or a mixture of both. Nanoparticles made from silica provide distinct advantages. They form porous networks that can carry therapeutic molecules throughout the body. Therefore, a nanomedical approach has been designed using silica nanoparticles as a porous delivery vehicle hydralazine. The silica nanoparticles are formed in a one-step method that incorporates poly(ethylene) glycol (PEG), a stealth molecule, directly onto the nanoparticles. As an additional avenue for study, a natural product in green tea, epigallocatechin gallate (EGCG), has been explored for its ability to react with acrolein, disabling its reactive capabilities. Upon demonstration of attenuating acrolein, EGCG's delivery may also be improved using the nanomedical approach. The

  19. Mesoporous silica nanoparticles for treating spinal cord injury

    NASA Astrophysics Data System (ADS)

    White-Schenk, Désirée.; Shi, Riyi; Leary, James F.

    2013-02-01

    An estimated 12,000 new cases of spinal cord injury (SCI) occur every year in the United States. A small oxidative molecule responsible for secondary injury, acrolein, is an important target in SCI. Acrolein attacks essential proteins and lipids, creating a feed-forward loop of oxidative stress in both the primary injury area and the surrounding areas. A small molecule used and FDA-approved for hypertension, hydralazine, has been found to "scavenge" acrolein after injury, but its delivery and short half-life, as well as its hypertension effects, hinder its application for SCI. Nanomedical systems broaden the range of therapeutic availability and efficacy over conventional medicine. They allow for targeted delivery of therapeutic molecules to tissues of interest, reducing side effects of untargeted therapies in unwanted areas. Nanoparticles made from silica form porous networks that can carry therapeutic molecules throughout the body. To attenuate the acrolein cascade and improve therapeutic availability, we have used a one-step, modified Stober method to synthesize two types of silica nanoparticles. Both particles are "stealth-coated" with poly(ethylene) glycol (PEG) (to minimize interactions with the immune system and to increase circulation time), which is also a therapeutic agent for SCI by facilitating membrane repair. One nanoparticle type contains an amine-terminal PEG (SiNP-mPEG-Am) and the other possesses a terminal hydrazide group (SiNP-mPEG-Hz). The former allows for exploration of hydralazine delivery, loading, and controlled release. The latter group has the ability to react with acrolein, allowing the nanoparticle to scavenge directly. The nanoparticles have been characterized and are being explored using neuronal PC-12 cells in vitro, demonstrating the potential of novel silica nanoparticles for use in attenuating secondary injury after SCI.

  20. Mesoporous silica nanoparticles for bioadsorption, enzyme immobilisation, and delivery carriers

    NASA Astrophysics Data System (ADS)

    Popat, Amirali; Hartono, Sandy Budi; Stahr, Frances; Liu, Jian; Qiao, Shi Zhang; Qing (Max) Lu, Gao

    2011-07-01

    Mesoporous silica nanoparticles (MSNs) provide a non-invasive and biocompatible delivery platform for a broad range of applications in therapeutics, pharmaceuticals and diagnosis. The creation of smart, stimuli-responsive systems that respond to subtle changes in the local cellular environment are likely to yield long term solutions to many of the current drug/gene/DNA/RNA delivery problems. In addition, MSNs have proven to be promising supports for enzyme immobilisation, enabling the enzymes to retain their activity, affording them greater potential for wide applications in biocatalysis and energy. This review provides a comprehensive summary of the advances made in the last decade and a future outlook on possible applications of MSNs as nanocontainers for storage and delivery of biomolecules. We discuss some of the important factors affecting the adsorption and release of biomolecules in MSNs and review of the cytotoxicity aspects of such nanomaterials. The review also highlights some promising work on enzyme immobilisation using mesoporous silica nanoparticles.

  1. Multi-photon imaging of amine-functionalized silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Natalio, Filipe; Kashyap, Anubha; Lorenz, Steffen; Kerschbaumer, Hannes; Dietzsch, Michael; Tahir, Muhammad Nawaz; Duschner, Heinz; Strand, Susanne; Strand, Dennis; Tremel, Wolfgang

    2012-07-01

    A convenient and simple strategy for preparing water soluble, photoluminescent functionalized silica nanoparticles (M-dots) in the absence of fluorophores or metal doping is demonstrated. These M-dots can be used for bioimaging using one and two-photon microscopy. Because of their high photostability, low toxicity and high biocompatibility compared with Lumidot™ CdSe/ZnS quantum dots, functionalized silica particles are superior alternatives for current bioimaging platforms. Moreover, the presence of a free amine group at the surface of the M-dots allows biomolecule conjugation (e.g. with antibodies, proteins) in a single step for converting these photoluminescent SiO2 nanoparticles into multifunctional efficient vehicles for theragnostics.A convenient and simple strategy for preparing water soluble, photoluminescent functionalized silica nanoparticles (M-dots) in the absence of fluorophores or metal doping is demonstrated. These M-dots can be used for bioimaging using one and two-photon microscopy. Because of their high photostability, low toxicity and high biocompatibility compared with Lumidot™ CdSe/ZnS quantum dots, functionalized silica particles are superior alternatives for current bioimaging platforms. Moreover, the presence of a free amine group at the surface of the M-dots allows biomolecule conjugation (e.g. with antibodies, proteins) in a single step for converting these photoluminescent SiO2 nanoparticles into multifunctional efficient vehicles for theragnostics. Electronic supplementary information (ESI) available: TEM images of unfunctionalized, XRD, UV-Vis spectra, XPS spectra and gallery of two-photon images. See DOI: 10.1039/c2nr30660c

  2. Highly ordered mesoporous silica nanoparticles and their application to DNA separation

    NASA Astrophysics Data System (ADS)

    Lee, Hye Sun; Chang, Jeong Ho

    2008-12-01

    This work describes the innovative development of high throughput human DNA purification process using the molecular self-assembled mesoporous silica nanoparticles. The mesoporous silica nanoparticles were prepared by sol-gel method and the formation of molecular self-assembled monolayers with functional groups was chemically demonstrated. The surface modification of functional groups was performed with aminofunctionallized organic silanes on mesoporous silica nanoparticles and the results of DNA separation was represented with electrophoresis images.

  3. Sonochemical synthesis of (3-aminopropyl)triethoxysilane-modified monodispersed silica nanoparticles for protein immobilization

    SciTech Connect

    Shen, Shou-Cang; Ng, Wai Kiong; Chia, Leonard; Dong, Yuan-Cai; Tan, Reginald B.H.

    2011-10-15

    Graphical abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by rapid sonochemical co-condensation to achieve high capability for protein immobilization. Highlights: {yields} Amino-modified monodispersed silica nanoparticles were synthesized by rapid co-condensation. {yields} Strong positive charge was created by aminopropyl-modification. {yields} Capability for immobilization of negatively charged protein was enhanced. {yields} Electrostatic interaction between proteins and surface contributed to the enhanced adsorption. -- Abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by a rapid sonochemical co-condensation synthesis procedure. The chemical nature of surface organic modifier on the obtained modified silica nanoparticle was characterized by {sup 13}C and {sup 29}Si MAS Nuclear Magnetic Resonance (NMR) spectroscopies, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA)- differential scanning calorimetry (DSC). Due to the strengthened positive surface charge of the silica nanoparticles by the modification with aminopropyl groups, the capability for bovine serum albumin (BSA) adsorption was significantly increased as compared with bare silica nanoparticles. 80 mg/g BSA was adsorbed on modified silica nanoparticles, whereas only 20 mg/g BSA could be loaded on pure silica nanoparticles. The enhanced positive surface charge repelled proteins with net positive charge and the modified silica nanoparticles exhibited negligible adsorption of lysozyme, thus a selective adsorption of proteins could be achieved.

  4. Multimodality Imaging with Silica-Based Targeted Nanoparticle Platforms

    SciTech Connect

    Jason S. Lewis

    2012-04-09

    Objectives: To synthesize and characterize a C-Dot silica-based nanoparticle containing 'clickable' groups for the subsequent attachment of targeting moieties (e.g., peptides) and multiple contrast agents (e.g., radionuclides with high specific activity) [1,2]. These new constructs will be tested in suitable tumor models in vitro and in vivo to ensure maintenance of target-specificity and high specific activity. Methods: Cy5 dye molecules are cross-linked to a silica precursor which is reacted to form a dye-rich core particle. This core is then encapsulated in a layer of pure silica to create the core-shell C-Dot (Figure 1) [2]. A 'click' chemistry approach has been used to functionalize the silica shell with radionuclides conferring high contrast and specific activity (e.g. 64Cu and 89Zr) and peptides for tumor targeting (e.g. cRGD and octreotate) [3]. Based on the selective Diels-Alder reaction between tetrazine and norbornene, the reaction is bioorthogonal, highyielding, rapid, and water-compatible. This radiolabeling approach has already been employed successfully with both short peptides (e.g. octreotate) and antibodies (e.g. trastuzumab) as model systems for the ultimate labeling of the nanoparticles [1]. Results: PEGylated C-Dots with a Cy5 core and labeled with tetrazine have been synthesized (d = 55 nm, zeta potential = -3 mV) reliably and reproducibly and have been shown to be stable under physiological conditions for up to 1 month. Characterization of the nanoparticles revealed that the immobilized Cy5 dye within the C-Dots exhibited fluorescence intensities over twice that of the fluorophore alone. The nanoparticles were successfully radiolabeled with Cu-64. Efforts toward the conjugation of targeting peptides (e.g. cRGD) are underway. In vitro stability, specificity, and uptake studies as well as in vivo imaging and biodistribution investigations will be presented. Conclusions: C-Dot silica-based nanoparticles offer a robust, versatile, and multi

  5. Biocide silver nanoparticles in two different silica-based coating

    NASA Astrophysics Data System (ADS)

    Babapour, A.; Yang, B.; Bahang, S.; Cao, W.

    2012-09-01

    Silica-based coatings containing biocide silver nanoparticles have been synthesized using low temperature sol-gel method. Two different silane based matrices, phenyltriethoxysilane (PhTEOS) and tetraethyl orthosilicate (TEOS), were selected as precursor to prepare silica-based film. The films were analyzed by using UV-visible spectrophotometry, atomic force microscopy (AFM) and scanning electron microscopy (SEM) for their optical, surface morphological as well as structural properties. Optical properties of nanosilver in these two matrices showed that the peak absorption observed at different wavelength, which is due to the fact that optical absorption of nanoparticles is affected by the surrounding medium. It is also found that the silver absorption has higher intensity in PhTEOS than in TEOS matrix, indicating higher concentration of silver nanoparticles being loaded into the coating. To study silver release property, the films were immersed in water for 12 and 20 days. AFM and SEM analyzes present that higher concentration of silver nanoparticles and smaller particle sizes were synthesis in PhTEOS coating and consequently, more particles remains on the surfaces after 20 days which leads to longer antibacterial activity of PhTEOS coating.

  6. M2 polarization enhances silica nanoparticle uptake by macrophages.

    PubMed

    Hoppstädter, Jessica; Seif, Michelle; Dembek, Anna; Cavelius, Christian; Huwer, Hanno; Kraegeloh, Annette; Kiemer, Alexandra K

    2015-01-01

    While silica nanoparticles have enabled numerous industrial and medical applications, their toxicological safety requires further evaluation. Macrophages are the major cell population responsible for nanoparticle clearance in vivo. The prevailing macrophage phenotype largely depends on the local immune status of the host. Whereas M1-polarized macrophages are considered as pro-inflammatory macrophages involved in host defense, M2 macrophages exhibit anti-inflammatory and wound-healing properties, but also promote tumor growth. We employed different models of M1 and M2 polarization: granulocyte-macrophage colony-stimulating factor/lipopolysaccharide (LPS)/interferon (IFN)-γ was used to generate primary human M1 cells and macrophage colony-stimulating factor (M-CSF)/interleukin (IL)-10 to differentiate M2 monocyte-derived macrophages (MDM). PMA-differentiated THP-1 cells were polarized towards an M1 type by LPS/IFN-γ and towards M2 by IL-10. Uptake of fluorescent silica nanoparticles (Ø26 and 41 nm) and microparticles (Ø1.75 μm) was quantified. At the concentration used (50 μg/ml), silica nanoparticles did not influence cell viability as assessed by MTT assay. Nanoparticle uptake was enhanced in M2-polarized primary human MDM compared with M1 cells, as shown by flow cytometric and microscopic approaches. In contrast, the uptake of microparticles did not differ between M1 and M2 phenotypes. M2 polarization was also associated with increased nanoparticle uptake in the macrophage-like THP-1 cell line. In accordance, in vivo polarized M2-like primary human tumor-associated macrophages obtained from lung tumors took up more nanoparticles than M1-like alveolar macrophages isolated from the surrounding lung tissue. In summary, our data indicate that the M2 polarization of macrophages promotes nanoparticle internalization. Therefore, the phenotypical differences between macrophage subsets should be taken into consideration in future investigations on nanosafety, but

  7. M2 polarization enhances silica nanoparticle uptake by macrophages

    PubMed Central

    Hoppstädter, Jessica; Seif, Michelle; Dembek, Anna; Cavelius, Christian; Huwer, Hanno; Kraegeloh, Annette; Kiemer, Alexandra K.

    2015-01-01

    While silica nanoparticles have enabled numerous industrial and medical applications, their toxicological safety requires further evaluation. Macrophages are the major cell population responsible for nanoparticle clearance in vivo. The prevailing macrophage phenotype largely depends on the local immune status of the host. Whereas M1-polarized macrophages are considered as pro-inflammatory macrophages involved in host defense, M2 macrophages exhibit anti-inflammatory and wound-healing properties, but also promote tumor growth. We employed different models of M1 and M2 polarization: granulocyte-macrophage colony-stimulating factor/lipopolysaccharide (LPS)/interferon (IFN)-γ was used to generate primary human M1 cells and macrophage colony-stimulating factor (M-CSF)/interleukin (IL)-10 to differentiate M2 monocyte-derived macrophages (MDM). PMA-differentiated THP-1 cells were polarized towards an M1 type by LPS/IFN-γ and towards M2 by IL-10. Uptake of fluorescent silica nanoparticles (Ø26 and 41 nm) and microparticles (Ø1.75 μm) was quantified. At the concentration used (50 μg/ml), silica nanoparticles did not influence cell viability as assessed by MTT assay. Nanoparticle uptake was enhanced in M2-polarized primary human MDM compared with M1 cells, as shown by flow cytometric and microscopic approaches. In contrast, the uptake of microparticles did not differ between M1 and M2 phenotypes. M2 polarization was also associated with increased nanoparticle uptake in the macrophage-like THP-1 cell line. In accordance, in vivo polarized M2-like primary human tumor-associated macrophages obtained from lung tumors took up more nanoparticles than M1-like alveolar macrophages isolated from the surrounding lung tissue. In summary, our data indicate that the M2 polarization of macrophages promotes nanoparticle internalization. Therefore, the phenotypical differences between macrophage subsets should be taken into consideration in future investigations on nanosafety, but

  8. Sodium hydroxide catalyzed monodispersed high surface area silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Bhakta, Snehasis; Dixit, Chandra K.; Bist, Itti; Abdel Jalil, Karim; Suib, Steven L.; Rusling, James F.

    2016-07-01

    Understanding of the synthesis kinetics and our ability to modulate medium conditions allowed us to generate nanoparticles via an ultra-fast process. The synthesis medium is kept quite simple with tetraethyl orthosilicate (TEOS) as precursor and 50% ethanol and sodium hydroxide catalyst. Synthesis is performed under gentle conditions at 20 °C for 20 min Long synthesis time and catalyst-associated drawbacks are most crucial in silica nanoparticle synthesis. We have addressed both these bottlenecks by replacing the conventional Stober catalyst, ammonium hydroxide, with sodium hydroxide. We have reduced the overall synthesis time from 20 to 1/3 h, ∼60-fold decrease, and obtained highly monodispersed nanoparticles with 5-fold higher surface area than Stober particles. We have demonstrated that the developed NPs with ∼3-fold higher silane can be used as efficient probes for biosensor applications.

  9. Morphology and Optical Properties of Bare and Silica Coated Hybrid Silver Nanoparticles.

    PubMed

    Ghimire, Sushant; Lebek, Werner; Godehardt, Reinhold; Lee, Wan In; Adhikari, Rameshwar

    2016-05-01

    Owing to their wide applications in the field of optoelectronics, photonics, catalysis, and medicine; plasmonic metal nanoparticles are attaining considerable interest nowadays. The optical properties of these metal nanoparticles depend upon their size, shape, and surrounding medium. The present work studies the morphology and optical properties of bare silver nanoparticles and silica coated hybrid silver nanoparticles. Aqueous phase mediated synthesis and water-in-oil microemulsion mediated synthesis are two different wet chemical routes employed for nanosynthesis. Direct coating of silica is performed in water-in-oil microemulsion on pre-synthesized silver nanoparticles using tetraethyl orthosilicate as silica precursor. This study shows that using different wet chemical routes the size of the synthesized nanoparticles could be tuned. In addition, using reverse micelles as nanoreactors, the thickness of the silica shell around the core silver nanoparticles could be significantly controlled. Further, the optical properties of silver nanoparticles could be adjusted through the size and the surface coating. PMID:27483900

  10. Microwave-assisted silica coating and photocatalytic activities of ZnO nanoparticles

    SciTech Connect

    Siddiquey, Iqbal Ahmed; Furusawa, Takeshi; Sato, Masahide; Suzuki, Noboru

    2008-12-01

    A new and rapid method for silica coating of ZnO nanoparticles by the simple microwave irradiation technique is reported. Silica-coated ZnO nanoparticles were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), CHN elemental analysis and zeta potential measurements. The FT-IR spectra and XPS clearly confirmed the silica coating on ZnO nanoparticles. The results of XPS analysis showed that the elements in the coating at the surface of the ZnO nanoparticles were Zn, O and Si. HR-TEM micrographs revealed a continuous and uniform dense silica coating layer of about 3 nm in thickness on the surface of ZnO nanoparticles. In addition, the silica coating on the ZnO nanoparticles was confirmed by the agreement in the zeta potential of the silica-coated ZnO nanoparticles with that of SiO{sub 2}. The results of the photocatalytic degradation of methylene blue (MB) in aqueous solution showed that silica coating effectively reduced the photocatalytic activity of ZnO nanoparticles. Silica-coated ZnO nanoparticles showed excellent UV shielding ability and visible light transparency.

  11. Chemoradiotherapeutic wrinkled mesoporous silica nanoparticles for use in cancer therapy

    SciTech Connect

    Munaweera, Imalka; Balkus, Kenneth J. Jr. E-mail: Anthony.DiPasqua@unthsc.edu; Koneru, Bhuvaneswari; Shi, Yi; Di Pasqua, Anthony J. E-mail: Anthony.DiPasqua@unthsc.edu

    2014-11-01

    Over the last decade, the development and application of nanotechnology in cancer detection, diagnosis, and therapy have been widely reported. Engineering of vehicles for the simultaneous delivery of chemo- and radiotherapeutics increases the effectiveness of the therapy and reduces the dosage of each individual drug required to produce an observable therapeutic response. We here developed a novel chemoradiotherapeutic 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid coated/uncoated platinum drug loaded, holmium-containing, wrinkled mesoporous silica nanoparticle. The materials were characterized with TEM, FTIR, {sup 1}H NMR, energy dispersive x-ray, inductively coupled plasma-mass spectrometry, and zeta potential measurements. In vitro platinum drug release from both lipid coated and uncoated chemoradiotherapeutic wrinkled mesoporous silica are reported. Various kinetic models were used to analyze the release kinetics. The radioactivity of the chemoradiotherapeutic nanocarriers was measured after neutron-activation.

  12. Chemoradiotherapeutic wrinkled mesoporous silica nanoparticles for use in cancer therapy

    NASA Astrophysics Data System (ADS)

    Munaweera, Imalka; Koneru, Bhuvaneswari; Shi, Yi; Di Pasqua, Anthony J.; Balkus, Kenneth J., Jr.

    2014-11-01

    Over the last decade, the development and application of nanotechnology in cancer detection, diagnosis, and therapy have been widely reported. Engineering of vehicles for the simultaneous delivery of chemo- and radiotherapeutics increases the effectiveness of the therapy and reduces the dosage of each individual drug required to produce an observable therapeutic response. We here developed a novel chemoradiotherapeutic 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid coated/uncoated platinum drug loaded, holmium-containing, wrinkled mesoporous silica nanoparticle. The materials were characterized with TEM, FTIR, 1H NMR, energy dispersive x-ray, inductively coupled plasma-mass spectrometry, and zeta potential measurements. In vitro platinum drug release from both lipid coated and uncoated chemoradiotherapeutic wrinkled mesoporous silica are reported. Various kinetic models were used to analyze the release kinetics. The radioactivity of the chemoradiotherapeutic nanocarriers was measured after neutron-activation.

  13. The infrared fingerprint signals of silica nanoparticles and its application in immunoassay

    NASA Astrophysics Data System (ADS)

    Ding, Yadan; Chu, Xueying; Hong, Xia; Zou, Peng; Liu, Yichun

    2012-01-01

    Infrared absorption properties of silica nanoparticles were studied. The transverse optical and the longitudinal optical phonon modes from the silica were proved to be the characteristic spectroscopic fingerprint signals. Based on this, a sandwich-structured immunoassay was performed, and the detection of the analyte (human IgG) was achieved by using biofunctional silica nanoparticles as infrared probes. The immunoassay based on Fourier transform infrared reflection absorption spectroscopy of silica nanoparticles shows significant value for potential applications in many areas, such as biomedicine, food safety, and waste treatment.

  14. One-pot synthesis of silica-coated copper nanoparticles with high chemical and thermal stability.

    PubMed

    Shiomi, Shohei; Kawamori, Makoto; Yagi, Shunsuke; Matsubara, Eiichiro

    2015-12-15

    With the recent development of nanotechnology, enhancement of the stability of nanomaterials is becoming ever more important for their practical applications. We studied the silica-coating of Cu nanoparticles and the enhanced stability of silica-coated Cu nanoparticles to oxidation. The metallic nanoparticles are easily oxidized and agglomerated compared with the bulk metals because the nanoparticles possess large specific surfaces. The Cu nanoparticle is one of the most difficult nanoparticles to be handled due to its absence of the oxidation stability. In the synthesis of silica-coated Cu nanoparticles via a sol-gel process using tetraethyl orthosilicate, the addition of NH3 as a catalyst of sol-gel reaction yielded homogeneous silica-coating. However, a large amount of Cu nanoparticles is instantly dissolved by forming complex ions in a NH3 solution during and before the silica-coating process. This is the difficulty in the silica-coating of Cu nanoparticles. In the present work, the dissolution behavior of Cu nanoparticles was electrochemically examined. This electrochemistry-based optimization of reducing power of a reaction bath enabled us to synthesize the silica-coated Cu nanoparticle via a consecutive liquid-phase reaction which requires only basic equipment and involves no separate centrifuging or extraction step. Cu nanoparticles coated by silica shells had the remarkable stability even in the presence of a strong oxidizing agent. Furthermore, we demonstrated that the highly stable Cu nanoparticles can be applied to a red pigment using a unique red color of Cu nanoparticles because of its surface plasmon resonance. PMID:26313712

  15. Gold nanorods-silica Janus nanoparticles for theranostics

    NASA Astrophysics Data System (ADS)

    Wang, Ying-Shuai; Shao, Dan; Zhang, Lu; Zhang, Xu-Lin; Li, Jing; Feng, Jing; Xia, Hong; Huo, Qi-Sheng; Dong, Wen-Fei; Sun, Hong-Bo

    2015-04-01

    A multi-functional gold nanorods-mesoporous silica Janus nanoparticles (NPs) were fabricated by a facile and mild strategy. These Janus NPs not only exhibit small shift of the local surface plasmon resonance wavelength but also have high potential for drug loading and low cytotoxicity. More importantly, the Janus nano-composites could efficiently deliver the imaging agents or drugs into liver cancer cells, at the same time the Janus NPs have good effect on photothermal, which indicate that the unique Janus NPs could be a promising candidate of theranostic system for combined photothermo-/chemo-cancer therapy.

  16. Producing ultra-thin silica coatings on iron-oxide nanoparticles to improve their surface reactivity

    NASA Astrophysics Data System (ADS)

    Kralj, Slavko; Makovec, Darko; Čampelj, Stanislav; Drofenik, Miha

    2010-07-01

    The reactivity of the relatively inert surfaces of iron-oxide magnetic nanoparticles can be significantly improved by coating the surfaces with silica. Unfortunately, however, this nonmagnetic silica layer tends to dilute the magnetic properties of the nanoparticles. Therefore, the silica layer should be as continuous, homogeneous, and as thin as possible. In this investigation we coated superparamagnetic maghemite nanoparticles by hydrolysis and the polycondensation of tetraethyl orthosilicate (TEOS), with the ethanol solution of TEOS being added to a stable suspension of citric acid-coated nanoparticles. The influences of the various parameters of the procedure on the quality of the coatings were systematically evaluated. The quality of the silica layer was characterized using electron microscopy and by performing leaching of the nanoparticles in HCl, while the surface reactivity was tested by grafting (3-aminopropyl) triethoxysilane (APS) onto the nanoparticles. We observed that the surface concentration of the grafted APS strongly increased when the nanoparticles were coated with a silica layer. The choice of experimental conditions for the coating procedure that favors the heterogeneous nucleation of silica on the surfaces of the nanoparticles enabled the preparation of very thin silica layers, less than 2 nm thick. By decreasing the amount of added TEOS to correspond to a monolayer of -Si-OH at the nanoparticles' surfaces, their surface reactivity could be very much improved, and with a reduction in their magnetization of only ˜10%.

  17. Passive targeting of ischemic-reperfused myocardium with adenosine-loaded silica nanoparticles

    PubMed Central

    Galagudza, Michael; Korolev, Dmitry; Postnov, Viktor; Naumisheva, Elena; Grigorova, Yulia; Uskov, Ivan; Shlyakhto, Eugene

    2012-01-01

    Pharmacological agents suggested for infarct size limitation have serious side effects when used at cardioprotective doses which hinders their translation into clinical practice. The solution to the problem might be direct delivery of cardioprotective drugs into ischemic-reperfused myocardium. In this study, we explored the potential of silica nanoparticles for passive delivery of adenosine, a prototype cardioprotective agent, into ischemic-reperfused heart tissue. In addition, the biodegradation of silica nanoparticles was studied both in vitro and in vivo. Immobilization of adenosine on the surface of silica nanoparticles resulted in enhancement of adenosine-mediated infarct size limitation in the rat model. Furthermore, the hypotensive effect of adenosine was attenuated after its adsorption on silica nanoparticles. We conclude that silica nanoparticles are biocompatible materials that might potentially be used as carriers for heart-targeted drug delivery. PMID:22619519

  18. Mesoporous-Silica-Functionalized Nanoparticles for Drug Delivery.

    PubMed

    Giret, Simon; Wong Chi Man, Michel; Carcel, Carole

    2015-09-28

    The ever-growing interest for finding efficient and reliable methods for treatment of diseases has set a precedent for the design and synthesis of new functional hybrid materials, namely porous nanoparticles, for controlled drug delivery. Mesoporous silica nanoparticles (MSNPs) represent one of the most promising nanocarriers for drug delivery as they possess interesting chemical and physical properties, thermal and mechanical stabilities, and are biocompatibile. In particular, their easily functionalizable surface allows a large number of property modifications further improving their efficiency in this field. This Concept article deals with the advances on the novel methods of functionalizing MSNPs, inside or outside the pores, as well as within the walls, to produce efficient and smart drug carriers for therapy. PMID:26250991

  19. Lysosomal Dysfunction Caused by Cellular Accumulation of Silica Nanoparticles.

    PubMed

    Schütz, Irene; Lopez-Hernandez, Tania; Gao, Qi; Puchkov, Dmytro; Jabs, Sabrina; Nordmeyer, Daniel; Schmudde, Madlen; Rühl, Eckart; Graf, Christina M; Haucke, Volker

    2016-07-01

    Nanoparticles (NPs) are widely used as components of drugs or cosmetics and hold great promise for biomedicine, yet their effects on cell physiology remain poorly understood. Here we demonstrate that clathrin-independent dynamin 2-mediated caveolar uptake of surface-functionalized silica nanoparticles (SiNPs) impairs cell viability due to lysosomal dysfunction. We show that internalized SiNPs accumulate in lysosomes resulting in inhibition of autophagy-mediated protein turnover and impaired degradation of internalized epidermal growth factor, whereas endosomal recycling proceeds unperturbed. This phenotype is caused by perturbed delivery of cargo via autophagosomes and late endosomes to SiNP-filled cathepsin B/L-containing lysosomes rather than elevated lysosomal pH or altered mTOR activity. Given the importance of autophagy and lysosomal protein degradation for cellular proteostasis and clearance of aggregated proteins, these results raise the question of beneficial use of NPs in biomedicine and beyond. PMID:27226546

  20. Fluorescent Silica Nanoparticles with Multivalent Inhibitory Effects towards Carbonic Anhydrases.

    PubMed

    Touisni, Nadia; Kanfar, Nasreddine; Ulrich, Sébastien; Dumy, Pascal; Supuran, Claudiu T; Mehdi, Ahmad; Winum, Jean-Yves

    2015-07-13

    Multifunctional silica nanoparticles decorated with fluorescent and sulfonamide carbonic anhydrase (CA) inhibitors were prepared and investigated as multivalent enzyme inhibitors against the cytosolic isoforms hCA I and II and the transmembrane tumor-associated ones hCA IX and XII. Excellent inhibitory effects were observed with these nanoparticles, with KI values in the low nanomolar range (6.2-0.67 nM) against all tested isozymes. A significant multivalency effect was seen for the inhibition of the monomeric enzymes hCA I and II compared to the dimeric hCA IX and hCA XII isoforms, where no multivalent effect was observed, suggesting that the multivalent binding is occurring through enzyme clustering. PMID:25965260

  1. Superparamagnetic iron oxide nanoparticles incorporated into silica nanoparticles by inelastic collision via ultrasonic field: Role of colloidal stability

    SciTech Connect

    Sodipo, Bashiru Kayode; Azlan, Abdul Aziz

    2015-04-24

    Superparamagnetic iron oxide nanoparticles (SPION)/Silica composite nanoparticles were prepared by ultrasonically irradiating colloidal suspension of silica and SPION mixture. Both silica and SPION were synthesized independently via co-precipitation and sol-gel method, respectively. Their mixtures were sonicated at different pH between 3 and 5. Electrophoresis measurement and other physicochemical analyses of the products demonstrate that at lower pH SPION was found incorporated into the silica. However, at pH greater than 4, SPION was unstable and unable to withstand the turbulence flow and shock wave from the ultrasonic field. Results suggest that the formation of the SPION/silica composite nanoparticles is strongly related to the inelastic collision induced by ultrasonic irradiation. More so, the formation the composite nanoparticles via the ultrasonic field are dependent on the zeta potential and colloidal stability of the particles.

  2. Superparamagnetic iron oxide nanoparticles incorporated into silica nanoparticles by inelastic collision via ultrasonic field: Role of colloidal stability

    NASA Astrophysics Data System (ADS)

    Sodipo, Bashiru Kayode; Azlan, Abdul Aziz

    2015-04-01

    Superparamagnetic iron oxide nanoparticles (SPION)/Silica composite nanoparticles were prepared by ultrasonically irradiating colloidal suspension of silica and SPION mixture. Both silica and SPION were synthesized independently via co-precipitation and sol-gel method, respectively. Their mixtures were sonicated at different pH between 3 and 5. Electrophoresis measurement and other physicochemical analyses of the products demonstrate that at lower pH SPION was found incorporated into the silica. However, at pH greater than 4, SPION was unstable and unable to withstand the turbulence flow and shock wave from the ultrasonic field. Results suggest that the formation of the SPION/silica composite nanoparticles is strongly related to the inelastic collision induced by ultrasonic irradiation. More so, the formation the composite nanoparticles via the ultrasonic field are dependent on the zeta potential and colloidal stability of the particles.

  3. Size-dependent interaction of silica nanoparticles with different surfactants in aqueous solution.

    PubMed

    Kumar, Sugam; Aswal, Vinod K; Kohlbrecher, Joachim

    2012-06-26

    The size-dependent interaction of anionic silica nanoparticles with ionic (anionic and cationic) and nonionic surfactants has been studied using small-angle neutron scattering (SANS). The surfactants used are anionic sodium dodecyl sulfate (SDS), cationic dodecyltrimethyl ammonium bromide (DTAB), and nonionic decaoxyethylene n-dodecylether (C(12)E(10)). The measurements have been carried out for three different sizes of silica nanoparticles (8, 16, and 26 nm) at fixed concentrations (1 wt % each) of nanoparticles and surfactants. It is found that irrespective of the size of the nanoparticles there is no significant interaction evolved between like-charged nanoparticles and the SDS micelles leading to any structural changes. However, the strong attraction of oppositely charged DTAB micelles with silica nanoparticles results in the aggregation of nanoparticles. The number of micelles mediating the nanoparticle aggregation increases with the size of the nanoparticle. The aggregates are characterized by fractal structure where the fractal dimension is found to be constant (D ≈ 2.3) independent of the size of the nanoparticles and consistent with diffusion-limited-aggregation-type fractal morphology in these systems. In the case of nonionic surfactant C(12)E(10), micelles interact with the individual silica nanoparticles. The number of adsorbed micelles per nanoparticle increases drastically whereas the percentage of adsorbed micelles on nanoparticles decreases with the increase in the size of the nanoparticles. PMID:22655980

  4. Bifunctional hairy silica nanoparticles as high-performance additives for lubricant

    PubMed Central

    Sui, Tianyi; Song, Baoyu; Wen, Yu-ho; Zhang, Feng

    2016-01-01

    Bifunctional hairy silica nanoparticles (BHSNs), which are silica nanoparticles covered with alkyl and amino organic chains, were prepared as high-performance additives for lubricants. Compared with hairy silica nanoparticles covered by a single type of organic chain, binary hairy silica nanoparticles exhibit the advantages of both types of organic chains, which exhibit excellent compatibility with lubricants and adsorbability to metal surfaces. Nanoparticles with different ratios of amino and alkyl ligands were investigated. In comparison to an untreated lubricant, BHSNs reduce the friction coefficient and wear scar diameter by 40% and 60%, respectively. The wear mechanism of BHSNs was investigated, and the protective and filling effect of the nanoparticles improved because of collaboration of amino and alkyl ligands. PMID:26936117

  5. Bifunctional hairy silica nanoparticles as high-performance additives for lubricant.

    PubMed

    Sui, Tianyi; Song, Baoyu; Wen, Yu-Ho; Zhang, Feng

    2016-01-01

    Bifunctional hairy silica nanoparticles (BHSNs), which are silica nanoparticles covered with alkyl and amino organic chains, were prepared as high-performance additives for lubricants. Compared with hairy silica nanoparticles covered by a single type of organic chain, binary hairy silica nanoparticles exhibit the advantages of both types of organic chains, which exhibit excellent compatibility with lubricants and adsorbability to metal surfaces. Nanoparticles with different ratios of amino and alkyl ligands were investigated. In comparison to an untreated lubricant, BHSNs reduce the friction coefficient and wear scar diameter by 40% and 60%, respectively. The wear mechanism of BHSNs was investigated, and the protective and filling effect of the nanoparticles improved because of collaboration of amino and alkyl ligands. PMID:26936117

  6. Bifunctional hairy silica nanoparticles as high-performance additives for lubricant

    NASA Astrophysics Data System (ADS)

    Sui, Tianyi; Song, Baoyu; Wen, Yu-Ho; Zhang, Feng

    2016-03-01

    Bifunctional hairy silica nanoparticles (BHSNs), which are silica nanoparticles covered with alkyl and amino organic chains, were prepared as high-performance additives for lubricants. Compared with hairy silica nanoparticles covered by a single type of organic chain, binary hairy silica nanoparticles exhibit the advantages of both types of organic chains, which exhibit excellent compatibility with lubricants and adsorbability to metal surfaces. Nanoparticles with different ratios of amino and alkyl ligands were investigated. In comparison to an untreated lubricant, BHSNs reduce the friction coefficient and wear scar diameter by 40% and 60%, respectively. The wear mechanism of BHSNs was investigated, and the protective and filling effect of the nanoparticles improved because of collaboration of amino and alkyl ligands.

  7. Silica nanoparticles for cell imaging and intracellular sensing

    NASA Astrophysics Data System (ADS)

    Korzeniowska, B.; Nooney, R.; Wencel, D.; McDonagh, C.

    2013-11-01

    There is increasing interest in the use of nanoparticles (NPs) for biomedical applications. In particular, nanobiophotonic approaches using fluorescence offers the potential of high sensitivity and selectivity in applications such as cell imaging and intracellular sensing. In this review, we focus primarily on the use of fluorescent silica NPs for these applications and, in so doing, aim to enhance and complement the key recent review articles on these topics. We summarize the main synthetic approaches, namely the Stöber and microemulsion processes, and, in this context, we deal with issues in relation to both covalent and physical incorporation of different types of dyes in the particles. The important issue of NP functionalization for conjugation to biomolecules is discussed and strategies published in the recent literature are highlighted and evaluated. We cite recent examples of the use of fluorescent silica NPs for cell imaging in the areas of cancer, stem cell and infectious disease research, and we review the current literature on the use of silica NPs for intracellular sensing of oxygen, pH and ionic species. We include a short final section which seeks to identify the main challenges and obstacles in relation to the potential widespread use of these particles for in vivo diagnostics and therapeutics.

  8. Colloidal mesoporous silica nanoparticles enhance the biological activity of resveratrol.

    PubMed

    Summerlin, Natalie; Qu, Zhi; Pujara, Naisarg; Sheng, Yong; Jambhrunkar, Siddharth; McGuckin, Michael; Popat, Amirali

    2016-08-01

    The naturally occurring polyphenol resveratrol (RES) has attracted increasing attention in recent years due to its antioxidant, anti-inflammatory, and anticancer activity. However, resveratrol's promising potential as a nutraceutical is hindered by its poor aqueous solubility, which limits its biological activity. Here we show that encapsulating resveratrol in colloidal mesoporous silica nanoparticles (MCM-48-RES) enhances its saturated solubility by ∼95% and increases its in vitro release kinetics compared to pure resveratrol. MCM-48-RES showed high loading capacity (20% w/w) and excellent encapsulation efficiency (100%). When tested against HT-29 and LS147T colon cancer cell lines, MCM-48-RES-mediated in vitro cell death was higher than that of pure resveratrol, mediated via the PARP and cIAP1 pathways. Finally, MCM-48-RES treatment also inhibited lipopolysaccharide-induced NF-κB activation in RAW264.7 cells, demonstrating improved anti-inflammatory activity. More broadly, our observations demonstrate the potential of colloidal mesoporous silica nanoparticles as next generation delivery carriers for hydrophobic nutraceuticals. PMID:27060664

  9. In Caenorhabditis elegans Nanoparticle-Bio-Interactions Become Transparent: Silica-Nanoparticles Induce Reproductive Senescence

    PubMed Central

    Bossinger, Olaf; von Mikecz, Anna

    2009-01-01

    While expectations and applications of nanotechnologies grow exponentially, little is known about interactions of engineered nanoparticles with multicellular organisms. Here we propose the transparent roundworm Caenorhabditis elegans as a simple but anatomically and biologically well defined animal model that allows for whole organism analyses of nanoparticle-bio-interactions. Microscopic techniques showed that fluorescently labelled nanoparticles are efficiently taken up by the worms during feeding, and translocate to primary organs such as epithelial cells of the intestine, as well as secondary organs belonging to the reproductive tract. The life span of nanoparticle-fed Caenorhabditis elegans remained unchanged, whereas a reduction of progeny production was observed in silica-nanoparticle exposed worms versus untreated controls. This reduction was accompanied by a significant increase of the ‘bag of worms’ phenotype that is characterized by failed egg-laying and usually occurs in aged wild type worms. Experimental exclusion of developmental defects suggests that silica-nanoparticles induce an age-related degeneration of reproductive organs, and thus set a research platform for both, detailed elucidation of molecular mechanisms and high throughput screening of different nanomaterials by analyses of progeny production. PMID:19672302

  10. Mechanized Silica Nanoparticles: A New Frontier in Theranostic Nanomedicine

    PubMed Central

    Ambrogio, Michael W.; Thomas, Courtney R.; Zhao, Yan-Li; Zink, Jeffrey I.; Stoddart, J. Fraser

    2011-01-01

    Conspectus Nanotechnology has been cited as a response to the most challenging issues facing society as a whole today. With nanoscale assemblies promising to improve on previously established therapeutic and diagnostic motifs, medicine stands to benefit significantly from advances in nanotechnology. To this end, the use of delivery platforms has attracted attention during the past decade, with researchers shifting their focus towards devising ways to deliver therapeutic and / or diagnostic agents, and away from developing new drug candidates. Metaphorically, the use of delivery platforms in medicine can be viewed as the “bow-and-arrow” approach, where the drugs are the arrows and the delivery vehicles are the bows. Even if one possesses the best arrows that money can buy, the arrows are not going to be useful if one does not have the appropriate bow to deliver the arrows to a desired location. The same can be said of drugs. Currently, a variety of strategies for delivering bioactive agents within living tissue exists. Dendrimers, polymers, micelles, vesicles, and nanoparticles have all been investigated for their use as possible delivery vehicles. With the growth of nanomedicine, one can then envisage the possibility in theranostic medicine of fabricating a vector that is capable of releasing simultaneously powerful therapeutics and diagnostic markers selectively to diseased tissue. In our design of new theranostic delivery systems, we have focused our attention on using mesoporous silica nanoparticles (SNPs). It is possible to store a payload of “cargo” molecules within such a robust platform that is stable to a wide range of chemical conditions. This stability allows SNPs to be functionalized with responsive mechanically interlocked molecules (MIMs) in the shape of bistable rotaxanes and psuedorotaxanes to yield mechanized silica nanoparticles (MSNPs). These MIMs can be designed in such a way that they either change shape or shed off some of their parts

  11. Sensitive and selective detection of trivalent chromium using Hyper Rayleigh Scattering with 5,5’-dithio-bis-(2-nitrobenzoic acid)-modified gold nanoparticles

    PubMed Central

    Hughes, Shantelle I.; Dasary, Samuel S. R.; Singh, Anant K.; Glenn, Zachery; Jamison, Hakim; Ray, Paresh C.; Yu, Hongtao

    2014-01-01

    Hyper Rayleigh Scattering (HRS) and absorption spectral assays using surface-modified gold nanoparticles (AuNP) have been developed for sensitive and selective detection of trivalent chromium (Cr3+) from other metal ions including hexavalent chromium (as Cr2O72−). Gold nanoparticles of 13 nm, covalently attached with 5,5’-dithio-bis-(2-nitrobenzoic acid) (AuNP-DTNBA), is used as a probe for both the absorption and HRS assays. AuNP-DTNBA is able to detect Cr3+ at 20 ppb level at pH 6.0 using absorption spectral change of the AuNP-DTNBA. Visible color change can be observed when mixed with 250 ppb of Cr3+, while there is no color change when mixed with 2 ppm level of some of the most common metal ions such as Cr2O72−, Hg2+, Ba2+, Fe3+, Pb2+, Na+, Zn2+, Cd2+, Co2+, Mn2+, Ca2+, and Ni2+. However, a color change is observed when mixed with Ni2+, Zn2+, and Cd2+ at a concentration higher than 2 ppm. The detection limit for the HRS assay is on a remarkable 25 ppt level, and there is no detectable HRS signal at 2 ppm level for Cr2O72−, Hg2+, Ba2+, Fe3+, Pb2+, Na+, Zn2+, Cd2+, Co2+, Mn2+, Ca2+, and Ni2+. PMID:24604926

  12. Preparation of spherical ceria coated silica nanoparticle abrasives for CMP application

    NASA Astrophysics Data System (ADS)

    Peedikakkandy, Lekha; Kalita, Laksheswar; Kavle, Pravin; Kadam, Ankur; Gujar, Vikas; Arcot, Mahesh; Bhargava, Parag

    2015-12-01

    This paper describes synthesis of spherical and highly mono-dispersed ceria coated silica nanoparticles of size ∼70-80 nm for application as abrasive particles in Chemical Mechanical Planarization (CMP) process. Core silica nanoparticles were initially synthesized using micro-emulsion method. Ceria coating on these ultrafine and spherical silica nanoparticles was achieved using controlled chemical precipitation method. Study of various parameters influencing the formation of ceria coated silica nanoparticles of size less than 100 nm has been undertaken and reported. Ceria coating over silica nanoparticles was varied by controlling the reaction temperature, pH and precursor concentrations. Characterization studies using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Energy Dispersive X-ray analysis show formation of crystalline CeO2 coating of ∼10 nm thickness over silica with spherical morphology and particle size <100 nm. Aqueous slurry of ceria coated silica abrasive was prepared and employed for polishing of oxide and nitride films on silicon substrates. Polished films were studied using ellipsometry and an improvement in SiO2:SiN selective removal rates up to 12 was observed using 1 wt% ceria coated silica nanoparticles slurry.

  13. Bioactive Silica Nanoparticles Reverse Age-Associated Bone Loss in Mice

    PubMed Central

    Vikulina, Tatyana; Roser-Page, Susanne; Lee, Jin-Kyu; Beck, George R.

    2015-01-01

    We recently reported that in vitro, engineered 50 nm spherical silica nanoparticles promote the differentiation and activity of bone building osteoblasts but suppress that of bone-resorbing osteoclasts. Furthermore, these nanoparticles promote bone accretion in young mice in vivo. In the present study the capacity of these nanoparticles to reverse bone loss in aged mice, a model of human senile osteoporosis, was investigated. Aged mice received nanoparticles weekly and bone mineral density (BMD), bone structure, and bone turnover was quantified. Our data revealed a significant increase in BMD, bone volume, and biochemical markers of bone formation. Biochemical and histological examinations failed to identify any abnormalities caused by nanoparticle administration. Our studies demonstrate that silica nanoparticles effectively blunt and reverse age-associated bone loss in mice by a mechanism involving promotion of bone formation. The data suggest that osteogenic silica nanoparticles may be a safe and effective therapeutic for counteracting age-associated bone loss. PMID:25680544

  14. Thermal stability of bimetallic Au/Fe nanoparticles in silica matrix

    SciTech Connect

    Pannu, Compesh Singh, Udai B. Hooda, Sonu Kabiraj, D. Avasthi, D. K.

    2014-04-24

    Thin silica film containing Au and Fe bimetallic nanoparticles were prepared by atom beam cosputtering. The samples were annealed at different temperatures from 400 to 800° C to study the thermal stability of bimetallic nanoparticles using X ray diffraction. It is observed that at 800° C strong structural rearrangement took place leading to thermal decomposition of bimetallic nanoparticles.

  15. Mesoporous silica nanoparticles for biomedical and catalytical applications

    SciTech Connect

    Sun, Xiaoxing

    2011-01-01

    Mesoporous silica materials, discovered in 1992 by the Mobile Oil Corporation, have received considerable attention in the chemical industry due to their superior textual properties such as high surface area, large pore volume, tunable pore diameter, and narrow pore size distribution. Among those materials, MCM-41, referred to Mobile Composition of Matter NO. 41, contains honeycomb liked porous structure that is the most common mesoporous molecular sieve studied. Applications of MCM-41 type mesoporous silica material in biomedical field as well as catalytical field have been developed and discussed in this thesis. The unique features of mesoporous silica nanoparticles were utilized for the design of delivery system for multiple biomolecules as described in chapter 2. We loaded luciferin into the hexagonal channels of MSN and capped the pore ends with gold nanoparticles to prevent premature release. Luciferase was adsorbed onto the outer surface of the MSN. Both the MSN and the gold nanoparticles were protected by poly-ethylene glycol to minimize nonspecific interaction of luciferase and keep it from denaturating. Controlled release of luciferin was triggered within the cells and the enzymatic reaction was detected by a luminometer. Further developments by varying enzyme/substrate pairs may provide opportunities to control cell behavior and manipulate intracellular reactions. MSN was also served as a noble metal catalyst support due to its large surface area and its stability with active metals. We prepared MSN with pore diameter of 10 nm (LP10-MSN) which can facilitate mass transfer. And we successfully synthesized an organo silane, 2,2'-Bipyridine-amide-triethoxylsilane (Bpy-amide-TES). Then we were able to functionalize LP10-MSN with bipyridinyl group by both post-grafting method and co-condensation method. Future research of this material would be platinum complexation. This Pt (II) complex catalyst has been reported for a C-H bond activation reaction as an

  16. Preparation of bio-compatible boron nanoparticles and novel mesoporous silica nanoparticles for bio-applications

    NASA Astrophysics Data System (ADS)

    Gao, Zhe

    This dissertation presents the synthesis and characterization of several novel inorganic and hybrid nanoparticles, including the bio-compatible boron nanoparticles (BNPs) for boron neutron capture therapy (BNCT), tannic acid-templated mesoporous silica nanoparticles and degradable bridged silsesquioxane silica nanoparticles. Chapter 1 provides background information of BNCT and reviews the development of design and synthesizing silica nanoparticles and the study of silica material degradability. Chapter 2 describes the preparation and characterization of dopamine modified BNPs and the preliminary cell study of them. The BNPs were first produced via ball milling, with fatty acid on the surface to stabilize the combustible boron elements. This chapter will mainly focus on the ligand-exchange strategy, in which the fatty acids were replaced by non-toxic dopamines in a facile one-pot reaction. The dopamine-coated BNPs (DA-BNPs) revealed good water dispersibility and low cytotoxicity. Chapter 3 describes the synthesis of tannic acid template mesoporous silica nanoparticles (TA-TEOS SiNPs) and their application to immobilize proteins. The monodispersed TA SiNPs with uniform pore size up to approximately 13 nm were produced by utilizing tannic acid as a molecular template. We studied the influence of TA concentration and reaction time on the morphology and pore size of the particles. Furthermore, the TA-TEOS particles could subsequently be modified with amine groups allowing them to be capable of incorporating imaging ligands and other guest molecules. The ability of the TA-TEOS particles to store biomolecules was preliminarily assessed with three proteins of different charge characteristics and dimensions. The immobilization of malic dehydrogenase on TA-TEOS enhanced the stability of the enzyme at room temperature. Chapter 4 details the synthesis of several bridged silsesquioxanes and the preparation of degradable hybrid SiNPs via co-condensation of bridged

  17. Membrane interactions of mesoporous silica nanoparticles as carriers of antimicrobial peptides.

    PubMed

    Braun, Katharina; Pochert, Alexander; Lindén, Mika; Davoudi, Mina; Schmidtchen, Artur; Nordström, Randi; Malmsten, Martin

    2016-08-01

    Membrane interactions are critical for the successful use of mesoporous silica nanoparticles as delivery systems for antimicrobial peptides (AMPs). In order to elucidate these, we here investigate effects of nanoparticle charge and porosity on AMP loading and release, as well as consequences of this for membrane interactions and antimicrobial effects. Anionic mesoporous silica particles were found to incorporate considerable amounts of the cationic AMP LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES (LL-37), whereas loading is much lower for non-porous or positively charged silica nanoparticles. Due to preferential pore localization, anionic mesoporous particles, but not the other particles, protect LL-37 from degradation by infection-related proteases. For anionic mesoporous nanoparticles, membrane disruption is mediated almost exclusively by peptide release. In contrast, non-porous silica particles build up a resilient LL-37 surface coating due to their higher negative surface charge, and display largely particle-mediated membrane interactions and antimicrobial effects. For positively charged mesoporous silica nanoparticles, LL-37 incorporation promotes the membrane binding and disruption displayed by the particles in the absence of peptide, but also causes toxicity against human erythrocytes. Thus, the use of mesoporous silica nanoparticles as AMP delivery systems requires consideration of membrane interactions and selectivity of both free peptide and the peptide-loaded nanoparticles, the latter critically dependent on nanoparticle properties. PMID:27174622

  18. Surface modification strategies on mesoporous silica nanoparticles for anti-biofouling zwitterionic film grafting.

    PubMed

    Khung, Yit Lung; Narducci, Dario

    2015-12-01

    In the past decade, zwitterionic-based anti-biofouling layers had gained much focus as a serious alternative to traditional polyhydrophilic films such as PEG. In the area of assembling silica nanoparticles with stealth properties, the incorporation of zwitterionic surface film remains fairly new but considering that silica nanoparticles had been widely demonstrated as useful biointerfacing nanodevice, zwitterionic film grafting on silica nanoparticle holds much potential in the future. This review will discuss on the conceivable functional chemistry approaches, some of which are potentially suitable for the assembly of such stealth systems. PMID:26589704

  19. Effect of acid and temperature on the discontinuous shear thickening phenomenon of silica nanoparticle suspensions

    NASA Astrophysics Data System (ADS)

    Li, Shuangbing; Wang, Jixiao; Cai, Wei; Zhao, Song; Wang, Zhi; Wang, Shichang

    2016-08-01

    The discontinuous shear thickening (DST) phenomenon of silica nanoparticle suspensions was investigated in this article. First, the non-aggregated silica nanoparticles were synthesized and characterized. The results indicate that the silica nanoparticles are spherical particles with a narrow size distribution with a diameter of approximately 90 nm. Next, the influence of nitric acid concentration and temperature on the DST phenomenon of shear thickening fluids (STFs) was investigated. The results indicate that the concentrated fluids with nitric acid concentration below 8.50 mmol/L and at a temperature below 40 °C exhibit a readily noticeable DST phenomenon.

  20. Citric acid modifies surface properties of commercial CeO2 nanoparticles reducing their toxicity and cerium uptake in radish (Raphanus sativus) seedlings.

    PubMed

    Trujillo-Reyes, J; Vilchis-Nestor, A R; Majumdar, S; Peralta-Videa, J R; Gardea-Torresdey, J L

    2013-12-15

    Little is known about the mobility, reactivity, and toxicity to plants of coated engineered nanoparticles (ENPs). Surface modification may change the interaction of ENPs with living organisms. This report describes surface changes in commercial CeO2 NPs coated with citric acid (CA) at molar ratios of 1:2, 1:3, 1:7, and 1:10 CeO2:CA, and their effects on radish (Raphanus sativus) seed germination, cerium and nutrients uptake. All CeO2 NPs and their absorption by radish plants were characterized by TEM, DLS, and ICP-OES. Radish seeds were germinated in pristine and CA coated CeO2 NPs suspensions at 50mg/L, 100mg/L, and 200mg/L. Deionized water and CA at 100mg/L were used as controls. Results showed ζ potential values of 21.6 mV and -56 mV for the pristine and CA coated CeO2 NPs, respectively. TEM images showed denser layers surrounding the CeO2 NPs at higher CA concentrations, as well as better distribution and smaller particle sizes. None of the treatments affected seed germination. However, at 200mg/L the CA coated NPs at 1:7 ratio produced significantly (p ≤ 0.05) more root biomass, increased water content and reduced by 94% the Ce uptake, compared to bare NPs. This suggests that CA coating decrease CeO2 NPs toxicity to plants. PMID:24231324

  1. Incorporation of Ln-Doped LaPO4 Nanocrystals as Luminescent Markers in Silica Nanoparticles.

    PubMed

    van Hest, Jacobine J H A; Blab, Gerhard A; Gerritsen, Hans C; Donega, Celso de Mello; Meijerink, Andries

    2016-12-01

    Lanthanide ions are promising for the labeling of silica nanoparticles with a specific luminescent fingerprint due to their sharp line emission at characteristic wavelengths. With the increasing use of silica nanoparticles in consumer products, it is important to label silica nanoparticles in order to trace the biodistribution, both in the environment and living organisms.In this work, we synthesized LaPO4 nanocrystals (NCs) with sizes ranging from 4 to 8 nm doped with europium or cerium and terbium. After silica growth using an inverse micelle method, monodisperse silica spheres were obtained with a single LaPO4 NC in the center. We demonstrate that the size of the silica spheres can be tuned in the 25-55 nm range by addition of small volumes of methanol during the silica growth reaction. Both the LaPO4 core and silica nanocrystal showed sharp line emission characteristic for europium and terbium providing unique optical labels in silica nanoparticles of variable sizes. PMID:27209405

  2. Improved gene transfer with histidine-functionalized mesoporous silica nanoparticles.

    PubMed

    Brevet, David; Hocine, Ouahiba; Delalande, Anthony; Raehm, Laurence; Charnay, Clarence; Midoux, Patrick; Durand, Jean-Olivier; Pichon, Chantal

    2014-08-25

    Mesoporous silica nanoparticles (MSN) were functionalized with aminopropyltriethoxysilane (MSN-NH2) then L-histidine (MSN-His) for pDNA delivery in cells and in vivo. The complexation of pDNA with MSN-NH2 and MSN-His was first studied with gel shift assay. pDNA complexed with MSN-His was better protected from DNase degradation than with MSN-NH2. An improvement of the transfection efficiency in cells was observed with MSN-His/pDNA compared to MSN-NH2/pDNA, which could be explained by a better internalization of MSN-His. The improvement of the transfection efficiency with MSN-His was also observed for gene transfer in Achilles tendons in vivo. PMID:24853464

  3. Rapid Imaging of Latent Fingerprints Using Biocompatible Fluorescent Silica Nanoparticles.

    PubMed

    Kim, Young-Jae; Jung, Hak-Sung; Lim, Joohyun; Ryu, Seung-Jin; Lee, Jin-Kyu

    2016-08-16

    Fluorescent silica nanoparticles (FSNPs) are synthesized through the Stöber method by incorporating silane-modified organic dye molecules. The modified fluorescent organic dye molecule is able to be prepared by allylation and hydrosilylation reactions. The optical properties of as-prepared FSNPs are shown the similar optical properties of PR254A (allylated Pigment Red 254) and have outstanding photostability. The polyvinylpyrrolidone (PVP) is introduced onto the surface of FSNP to enhance the binding affinity of PVP-coated FSNP for latent fingerprints (LFPs) detection. The simple preparation and easy control of surface properties of FSNPs show potential as a fluorescent labeling material for enhanced latent fingerprint detection on hydrophilic and hydrophobic substrates in forensic science for individual identification. PMID:27452188

  4. Mesoporous silica nanoparticles in tissue engineering--a perspective.

    PubMed

    Rosenholm, Jessica Maria; Zhang, Jixi; Linden, Mika; Sahlgren, Cecilia

    2016-02-01

    In this review, we summarize the latest developments and give a perspective on future applications of mesoporous silica nanoparticles (MSNs) in regenerative medicine. MSNs constitute a flexible platform for controlled delivery of drugs and imaging agents in tissue engineering and stem cell therapy. We highlight the recent advances in applying MSNs for controlled drug delivery and stem cell tracking. We touch upon novel functions of MSNs in real time imaging of drug release and biological function, and as tools to control the chemical and mechanical environment of stem cells. We discuss the need for novel model systems for studying biofunctionality and biocompatibility of MSNs, and how the interdisciplinary activities within the field will advance biotechnology research. PMID:26784861

  5. Porous thin films of functionalized mesoporous silica nanoparticles.

    PubMed

    Kobler, Johannes; Bein, Thomas

    2008-11-25

    The synthesis of extremely small mesoporous silica nanoparticles via a specific co-condensation process with phenyl groups is demonstrated. The suspensions are ideally suited for the production of nanoscale thin films by spin-coating. Thanks to the small particle size and the resulting low surface roughness, the films show excellent optical qualities and exhibit good diffusion properties and a highly accessible pore system. The availability of such homogeneous porous thin films made it possible to use ellipsometric porosimetry (EP) as a convenient method to determine the effective porosity of the films on their original support without destroying it. It was possible to record sorption isotherms of the thin films with ellipsometry and to correlate the data with nitrogen sorption data of dried powders of the same material. The thin films showed very low refractive indices of around 1.2. PMID:19206399

  6. Hydrogen and oxygen adsorption stoichiometries on silica supported ruthenium nanoparticles

    SciTech Connect

    Berthoud, Romain; Delichere, Pierre; Gajan, David; Lukens, Wayne; Pelzer, Katrin; Basset, Jean-Marie; Candy, Jean-Pierre; Coperet, Christophe

    2008-12-01

    Treatment under H{sub 2} at 300 C of Ru(COD)(COT) dispersed on silica yields 2 nm ruthenium nanoparticles, [Ru{sub p}/SiO{sub 2}], according to EXAFS, HRTEM and XPS. H{sub 2} adsorption measurements on [Ru{sub p}/SiO{sub 2}] in the absence of O{sub 2} show that Ru particles adsorb up to ca. 2 H per surface ruthenium atoms (2H/Ru{sub s}) on various samples; this technique can therefore be used to measure the dispersion of Ru particles. In contrast, O{sub 2} adsorption on [Ru{sub p}/SiO{sub 2}] leads to a partial oxidation of the bulk at 25 C, to RuO{sub 2} at 200 C and to sintering upon further reduction under H{sub 2}, showing that O{sub 2} adsorption cannot be used to measure the dispersion of Ru particles.

  7. In situ grafting silica nanoparticles reinforced nanocomposite hydrogels.

    PubMed

    Yang, Jun; Han, Chun-Rui; Duan, Jiu-Fang; Xu, Feng; Sun, Run-Cang

    2013-11-21

    Highly flexible nanocomposite hydrogels were prepared by using silica nanoparticles (SNPs) as fillers and multi-functional cross-links to graft hydrophilic poly(acrylic acid) (PAA) by free radical polymerization from an aqueous solution. The SNPs were collected by neighboring polymer chains and dispersed uniformly within a PAA matrix. The mechanical properties of the nanocomposite hydrogels were tailored by the concentration of SNPs according to the percolation model. It was proposed that covalent bonds of adsorbed chains on the filler surface resulted in the formation of a shell of an immobilized glassy layer and trapped entanglements, where the glassy polymer layer greatly enhanced the elastic modulus and the release of trapped entanglements at deformation contributed to the viscoelastic properties. PMID:24089085

  8. Breakable mesoporous silica nanoparticles for targeted drug delivery.

    PubMed

    Maggini, Laura; Cabrera, Ingrid; Ruiz-Carretero, Amparo; Prasetyanto, Eko A; Robinet, Eric; De Cola, Luisa

    2016-04-01

    "Pop goes the particle". Here we report on the preparation of redox responsive mesoporous organo-silica nanoparticles containing disulfide (S-S) bridges (ss-NPs) that, even upon the exohedral grafting of targeting ligands, retained their ability to undergo structural degradation, and increase their local release activity when exposed to a reducing agent. This degradation could be observed also inside glioma C6 cancer cells. Moreover, when anticancer drug-loaded pristine and derivatized ss-NPs were fed to glioma C6 cells, the responsive hybrids were more effective in their cytotoxic action compared to non-breakable particles. The possibility of tailoring the surface functionalization of this hybrid, yet preserving its self-destructive behavior and enhanced drug delivery properties, paves the way for the development of effective biodegradable materials for in vivo targeted drug delivery. PMID:26974603

  9. A comparative study of non-covalent encapsulation methods for organic dyes into silica nanoparticles

    PubMed Central

    2011-01-01

    Numerous luminophores may be encapsulated into silica nanoparticles (< 100 nm) using the reverse microemulsion process. Nevertheless, the behaviour and effect of such luminescent molecules appear to have been much less studied and may possibly prevent the encapsulation process from occurring. Such nanospheres represent attractive nanoplatforms for the development of biotargeted biocompatible luminescent tracers. Physical and chemical properties of the encapsulated molecules may be affected by the nanomatrix. This study examines the synthesis of different types of dispersed silica nanoparticles, the ability of the selected luminophores towards incorporation into the silica matrix of those nanoobjects as well as the photophysical properties of the produced dye-doped silica nanoparticles. The nanoparticles present mean diameters between 40 and 60 nm as shown by TEM analysis. Mainly, the photophysical characteristics of the dyes are retained upon their encapsulation into the silica matrix, leading to fluorescent silica nanoparticles. This feature article surveys recent research progress on the fabrication strategies of these dye-doped silica nanoparticles. PMID:21711855

  10. Superhydrophobicity of cotton fabrics treated with silica nanoparticles and water-repellent agent.

    PubMed

    Bae, Geun Yeol; Min, Byung Gil; Jeong, Young Gyu; Lee, Sang Cheol; Jang, Jin Ho; Koo, Gwang Hoe

    2009-09-01

    To obtain the superhydrophobic water-repellent cotton fabrics, cotton fabrics were treated with silica nanoparticles and/or a cost-effective water-repellent agent (WR agent). Two different silica nanoparticles were synthesized via a sol-gel process and their shapes, sizes, and compositions were characterized. It was found that silica particles are spherical and have diameters of 143 and 378 nm. For the cotton fabrics treated with the WR agent alone, the water contact angles on the fabric surface remained lower than 20 degrees at the WR agent concentration of 0.3 wt% or less. Silica nanoparticle treatment itself did not change the hydrophilic surface of cotton fabric, indicating that water drops were adsorbed into fabrics due to the hydroxyl groups on both cotton and silica nanoparticle surfaces. However, for the cotton fabrics treated with both silica nanoparticles and the WR agent, a contact angle above 130 degrees can be obtained even at the very low WR agent concentration of 0.1 wt%. Therefore, superhydrophobic cotton fabrics could be obtained via the combined treatment of silica nanoparticle and WR agent, which is cost effective compared with fluorinate silane treatment. PMID:19477460

  11. Breakable mesoporous silica nanoparticles for targeted drug delivery

    NASA Astrophysics Data System (ADS)

    Maggini, Laura; Cabrera, Ingrid; Ruiz-Carretero, Amparo; Prasetyanto, Eko A.; Robinet, Eric; de Cola, Luisa

    2016-03-01

    ``Pop goes the particle''. Here we report on the preparation of redox responsive mesoporous organo-silica nanoparticles containing disulfide (S-S) bridges (ss-NPs) that, even upon the exohedral grafting of targeting ligands, retained their ability to undergo structural degradation, and increase their local release activity when exposed to a reducing agent. This degradation could be observed also inside glioma C6 cancer cells. Moreover, when anticancer drug-loaded pristine and derivatized ss-NPs were fed to glioma C6 cells, the responsive hybrids were more effective in their cytotoxic action compared to non-breakable particles. The possibility of tailoring the surface functionalization of this hybrid, yet preserving its self-destructive behavior and enhanced drug delivery properties, paves the way for the development of effective biodegradable materials for in vivo targeted drug delivery.``Pop goes the particle''. Here we report on the preparation of redox responsive mesoporous organo-silica nanoparticles containing disulfide (S-S) bridges (ss-NPs) that, even upon the exohedral grafting of targeting ligands, retained their ability to undergo structural degradation, and increase their local release activity when exposed to a reducing agent. This degradation could be observed also inside glioma C6 cancer cells. Moreover, when anticancer drug-loaded pristine and derivatized ss-NPs were fed to glioma C6 cells, the responsive hybrids were more effective in their cytotoxic action compared to non-breakable particles. The possibility of tailoring the surface functionalization of this hybrid, yet preserving its self-destructive behavior and enhanced drug delivery properties, paves the way for the development of effective biodegradable materials for in vivo targeted drug delivery. Electronic supplementary information (ESI) available: Full experimental procedures, additional SEM and TEM images of particles, complete UV-Vis and PL-monitored characterization of the breakdown of

  12. Sol-Gel processing of silica nanoparticles and their applications.

    PubMed

    Singh, Lok P; Bhattacharyya, Sriman K; Kumar, Rahul; Mishra, Geetika; Sharma, Usha; Singh, Garima; Ahalawat, Saurabh

    2014-11-01

    Recently, silica nanoparticles (SNPs) have drawn widespread attention due to their applications in many emerging areas because of their tailorable morphology. During the last decade, remarkable efforts have been made on the investigations for novel processing methodologies to prepare SNPs, resulting in better control of the size, shape, porosity and significant improvements in the physio-chemical properties. A number of techniques available for preparing SNPs namely, flame spray pyrolysis, chemical vapour deposition, micro-emulsion, ball milling, sol-gel etc. have resulted, a number of publications. Among these, preparation by sol-gel has been the focus of research as the synthesis is straightforward, scalable and controllable. Therefore, this review focuses on the recent progress in the field of synthesis of SNPs exhibiting ordered mesoporous structure, their distribution pattern, morphological attributes and applications. The mesoporous silica nanoparticles (MSNPs) with good dispersion, varying morphology, narrow size distribution and homogeneous porous structure have been successfully prepared using organic and inorganic templates. The soft template assisted synthesis using surfactants for obtaining desirable shapes, pores, morphology and mechanisms proposed has been reviewed. Apart from single template, double and mixed surfactants, electrolytes, polymers etc. as templates have also been intensively discussed. The influence of reaction conditions such as temperature, pH, concentration of reagents, drying techniques, solvents, precursor, aging time etc. have also been deliberated. These MSNPs are suitable for a variety of applications viz., in the drug delivery systems, high performance liquid chromatography (HPLC), biosensors, cosmetics as well as construction materials. The applications of these SNPs have also been briefly summarized. PMID:25466691

  13. Magnetic mesoporous silica nanoparticles: fabrication and their laccase immobilization performance.

    PubMed

    Wang, Feng; Guo, Chen; Yang, Liang-rong; Liu, Chun-Zhao

    2010-12-01

    Newly large-pore magnetic mesoporous silica nanoparticles (MMSNPs) with wormhole framework structures were synthesized for the first time by using tetraethyl orthosilicate as the silica source and amine-terminated Jeffamine surfactants as template. Iminodiacerate was attached on these MMSNPs through a silane-coupling agent and chelated with Cu(2+). The Cu(2+)-chelated MMSNPs (MMSNPs-CPTS-IDA-Cu(2+)) showed higher adsorption capacity of 98.1 mg g(-1)-particles and activity recovery of 92.5% for laccase via metal affinity adsorption in comparison with MMSNPs via physical adsorption. The Michaelis constant (K(m)) and catalytic constant (k(cat)) of laccase immobilized on the MMSNPs-CPTS-IDA-Cu(2+) were 3.28 mM and 155.4 min(-1), respectively. Storage stability and temperature endurance of the immobilized laccase on MMSNPs-CPTS-IDA-Cu(2+) increased significantly, and the immobilized laccase retained 86.6% of its initial activity after 10 successive batch reactions operated with magnetic separation. PMID:20655206

  14. Surface modification of silica particles with gold nanoparticles as an augmentation of gold nanoparticle mediated laser perforation

    PubMed Central

    Kalies, Stefan; Gentemann, Lara; Schomaker, Markus; Heinemann, Dag; Ripken, Tammo; Meyer, Heiko

    2014-01-01

    Gold nanoparticle mediated (GNOME) laser transfection/perforation fulfills the demands of a reliable transfection technique. It provides efficient delivery and has a negligible impact on cell viability. Furthermore, it reaches high-throughput applicability. However, currently only large gold particles (> 80 nm) allow successful GNOME laser perforation, probably due to insufficient sedimentation of smaller gold nanoparticles. The objective of this study is to determine whether this aspect can be addressed by a modification of silica particles with gold nanoparticles. Throughout the analysis, we show that after the attachment of gold nanoparticles to silica particles, comparable or better efficiencies to GNOME laser perforation are reached. In combination with 1 µm silica particles, we report laser perforation with gold nanoparticles with sizes down to 4 nm. Therefore, our investigations have great importance for the future research in and the fields of laser transfection combined with plasmonics. PMID:25136494

  15. Surface modification of silica particles with gold nanoparticles as an augmentation of gold nanoparticle mediated laser perforation.

    PubMed

    Kalies, Stefan; Gentemann, Lara; Schomaker, Markus; Heinemann, Dag; Ripken, Tammo; Meyer, Heiko

    2014-08-01

    Gold nanoparticle mediated (GNOME) laser transfection/perforation fulfills the demands of a reliable transfection technique. It provides efficient delivery and has a negligible impact on cell viability. Furthermore, it reaches high-throughput applicability. However, currently only large gold particles (> 80 nm) allow successful GNOME laser perforation, probably due to insufficient sedimentation of smaller gold nanoparticles. The objective of this study is to determine whether this aspect can be addressed by a modification of silica particles with gold nanoparticles. Throughout the analysis, we show that after the attachment of gold nanoparticles to silica particles, comparable or better efficiencies to GNOME laser perforation are reached. In combination with 1 µm silica particles, we report laser perforation with gold nanoparticles with sizes down to 4 nm. Therefore, our investigations have great importance for the future research in and the fields of laser transfection combined with plasmonics. PMID:25136494

  16. Biomimetic synthesis of chiral erbium-doped silver/peptide/silica core-shell nanoparticles (ESPN).

    PubMed

    Mantion, Alexandre; Graf, Philipp; Florea, Ileana; Haase, Andrea; Thünemann, Andreas F; Mašić, Admir; Ersen, Ovidiu; Rabu, Pierre; Meier, Wolfgang; Luch, Andreas; Taubert, Andreas

    2011-12-01

    Peptide-modified silver nanoparticles have been coated with an erbium-doped silica layer using a method inspired by silica biomineralization. Electron microscopy and small-angle X-ray scattering confirm the presence of an Ag/peptide core and silica shell. The erbium is present as small Er(2)O(3) particles in and on the silica shell. Raman, IR, UV-Vis, and circular dichroism spectroscopies show that the peptide is still present after shell formation and the nanoparticles conserve a chiral plasmon resonance. Magnetic measurements find a paramagnetic behavior. In vitro tests using a macrophage cell line model show that the resulting multicomponent nanoparticles have a low toxicity for macrophages, even on partial dissolution of the silica shell. PMID:22031101

  17. Polystyrene-Core-Silica-Shell Hybrid Particles Containing Gold and Magnetic Nanoparticles.

    PubMed

    Tian, Jia; Vana, Philipp

    2016-02-18

    Polystyrene-core-silica-shell hybrid particles were synthesized by combining the self-assembly of nanoparticles and the polymer with a silica coating strategy. The core-shell hybrid particles are composed of gold-nanoparticle-decorated polystyrene (PS-AuNP) colloids as the core and silica particles as the shell. PS-AuNP colloids were generated by the self-assembly of the PS-grafted AuNPs. The silica coating improved the thermal stability and dispersibility of the AuNPs. By removing the "free" PS of the core, hollow particles with a hydrophobic cage having a AuNP corona and an inert silica shell were obtained. Also, Fe3O4 nanoparticles were encapsulated in the core, which resulted in magnetic core-shell hybrid particles by the same strategy. These particles have potential applications in biomolecular separation and high-temperature catalysis and as nanoreactors. PMID:26639677

  18. Label-Free Luminescent Mesoporous Silica Nanoparticles for Imaging and Drug Delivery

    PubMed Central

    Chen, Hongmin; Zhen, Zipeng; Tang, Wei; Todd, Trever; Chuang, Yen-Jun; Wang, Lianchun; Pan, Zhengwei; Xie, Jin

    2013-01-01

    We report herein a straightforward and label-free approach to prepare luminescent mesoporous silica nanoparticles. We found that calcination at 400 °C can grant mesoporous organosilica nanoparticles with strong fluorescence of great photo- and chemical stability. The luminescence is found to originate from the carbon dots generated from the calcination, rather than the defects in the silica matrix as was believed previously. The calcination does not impact the particles' abilities to load drugs and conjugate to biomolecules. In a proof-of-concept study, we demonstrated that doxorubicin (Dox) can be efficiently encapsulated into these fluorescent mesoporous silica nanoparticles. After coupled to c(RGDyK), the nanoconjugates can efficiently home to tumors through interactions with integrin αvβ3 overexpressed on the tumor vasculature. This calcination-induced luminescence is expected to find wide applications in silica-based drug delivery, nanoparticle coating, and immunofluorescence imaging. PMID:24052805

  19. Fabrication of pDMAEMA-coated silica nanoparticles and their enhanced antibacterial activity.

    PubMed

    Song, Jooyoung; Jung, Yujung; Lee, Inkyu; Jang, Jyongsik

    2013-10-01

    Thin pDMAEMA shells were formed on the surface of silica nanoparticles via vapor deposition polymerization. Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and elemental analysis have been used to characterize the resulting pDMAEMA-coated silica nanoparticles. Electron microscopy studies reveal that the thin polymer shell is formed on the silica surface. In this work, the particle diameter can be controlled (from ~19 to ~69 nm) by varying the size of silica core. The antibacterial performance of the core-shell nanoparticles was investigated against both Gram-positive (Escherichia coli) and Gram-negative (Staphylococcus aureus) bacteria. Importantly, the nano-sized pDMAEMA particles presented antibacterial activity against both bacteria without additional quaternization due to its enlarged surface area. Additionally, the bactericidal efficiency was enhanced by reducing the particle size, because the expanded surface area of the cationic polymer nanoparticles provides more active sites that can kill the bacteria. PMID:23838333

  20. Fabrication of autofluorescent porous silica nanoparticles for redox-responsive drug release.

    PubMed

    Cao, Na; Zhao, Yanbao; Sang, Bin; Wang, Zhihua; Cao, Liuqin; Sun, Lei; Zou, Xueyan

    2016-12-01

    Porous silica nanoparticles were prepared by emulsion-condensation route. The silica nanoparticles with diameter of 50nm have both accessible center-radial large pore channels (19.9nm) and small pore size of 3.5nm. The hierarchical porous structure endows them large pore volume for loading drugs and sustained release property. The silica nanoparticles were further modified with glucose-oxidized glutathione. The formulated Schiff base and disulfide bonds render the silica nanoparticles auto-fluorescent and redox-responsive properties. The cleavage of disulfide bonds caused by reactive thiols facilitates aminomethylbenzoic acid (AMA) release. The release of drug leads to the loss of fluorescence, which would be used to monitor the drug delivery and carrier distribution. PMID:27612720

  1. Quantification of Internalized Silica Nanoparticles via STED Microscopy

    PubMed Central

    Peuschel, Henrike; Ruckelshausen, Thomas; Cavelius, Christian; Kraegeloh, Annette

    2015-01-01

    The development of safe engineered nanoparticles (NPs) requires a detailed understanding of their interaction mechanisms on a cellular level. Therefore, quantification of NP internalization is crucial to predict the potential impact of intracellular NP doses, providing essential information for risk assessment as well as for drug delivery applications. In this study, the internalization of 25 nm and 85 nm silica nanoparticles (SNPs) in alveolar type II cells (A549) was quantified by application of super-resolution STED (stimulated emission depletion) microscopy. Cells were exposed to equal particle number concentrations (9.2 × 1010 particles mL−1) of each particle size and the sedimentation of particles during exposure was taken into account. Microscopy images revealed that particles of both sizes entered the cells after 5 h incubation in serum supplemented and serum-free medium. According to the in vitro sedimentation, diffusion, and dosimetry (ISDD) model 20–27% of the particles sedimented. In comparison, 102-103 NPs per cell were detected intracellularly serum-containing medium. Furthermore, in the presence of serum, no cytotoxicity was induced by the SNPs. In serum-free medium, large agglomerates of both particle sizes covered the cells whereas only high concentrations (≥ 3.8 × 1012 particles mL−1) of the smaller particles induced cytotoxicity. PMID:26125028

  2. Engineered silica nanoparticles as additives in lubricant oils

    NASA Astrophysics Data System (ADS)

    Díaz-Faes López, Teresa; Fernández González, Alfonso; Del Reguero, Ángel; Matos, María; Díaz-García, Marta E.; Badía-Laíño, Rosana

    2015-10-01

    Silica nanoparticles (SiO2 NPs) synthesized by the sol-gel approach were engineered for size and surface properties by grafting hydrophobic chains to prevent their aggregation and facilitate their contact with the phase boundary, thus improving their dispersibility in lubricant base oils. The surface modification was performed by covalent binding of long chain alkyl functionalities using lauric acid and decanoyl chloride to the SiO2 NP surface. The hybrid SiO2 NPs were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, simultaneous differential thermal analysis, nuclear magnetic resonance and dynamic light scattering, while their dispersion in two base oils was studied by static multiple light scattering at low (0.01% w/v) and high (0.50%w/v) concentrations. The nature of the functional layer and the functionalization degree seemed to be directly involved in the stability of the suspensions. The potential use of the functional SiO2 NPs as lubricant additives in base oils, specially designed for being used in hydraulic circuits, has been outlined by analyzing the tribological properties of the dispersions. The dendritic structure of the external layer played a key role in the tribological characteristics of the material by reducing the friction coefficient and wear. These nanoparticles reduce drastically the waste of energy in friction processes and are more environmentally friendly than other additives.

  3. Silica Nanoparticles Effects on Blood Coagulation Proteins and Platelets

    PubMed Central

    Gryshchuk, Volodymyr; Galagan, Natalya

    2016-01-01

    Interaction of nanoparticles with the blood coagulation is important prior to their using as the drug carriers or therapeutic agents. The aim of present work was studying of the primary effects of silica nanoparticles (SiNPs) on haemostasis in vitro. We studied the effect of SiNPs on blood coagulation directly estimating the activation of prothrombin and factor X and to verify any possible effect of SiNPs on human platelets. It was shown that SiNPs shortened coagulation time in APTT and PT tests and increased the activation of factor X induced by RVV possibly due to the sorption of intrinsic pathway factors on their surface. SiNPs inhibited the aggregation of platelet rich plasma induced by ADP but in the same time partially activated platelets as it was shown using flow cytometry. The possibility of SiNPs usage in nanomedicine is strongly dependant on their final concentration in bloodstream and the size of the particles that are used. However SiNPs are extremely promising as the haemostatic agents for preventing the blood loss after damage. PMID:26881078

  4. Mechanized silica nanoparticles: a new frontier in theranostic nanomedicine.

    PubMed

    Ambrogio, Michael W; Thomas, Courtney R; Zhao, Yan-Li; Zink, Jeffrey I; Stoddart, J Fraser

    2011-10-18

    Medicine can benefit significantly from advances in nanotechnology because nanoscale assemblies promise to improve on previously established therapeutic and diagnostic regimes. Over the past decade, the use of delivery platforms has attracted attention as researchers shift their focus toward new ways to deliver therapeutic and/or diagnostic agents and away from the development of new drug candidates. Metaphorically, the use of delivery platforms in medicine can be viewed as the "bow-and-arrow" approach, where the drugs are the arrows and the delivery vehicles are the bows. Even if one possesses the best arrows that money can buy, they will not be useful if one does not have the appropriate bow to deliver the arrows to their intended location. Currently, many strategies exist for the delivery of bioactive agents within living tissue. Polymers, dendrimers, micelles, vesicles, and nanoparticles have all been investigated for their use as possible delivery vehicles. With the growth of nanomedicine, one can envisage the possibility of fabricating a theranostic vector that could release powerful therapeutics and diagnostic markers simultaneously and selectively to diseased tissue. In our design of more robust theranostic delivery systems, we have focused our attention on using mesoporous silica nanoparticles (SNPs). The payload "cargo" molecules can be stored within this robust domain, which is stable to a wide range of chemical conditions. This stability allows SNPs to be functionalized with stimulus-responsive mechanically interlocked molecules (MIMs) in the shape of bistable rotaxanes and psuedorotaxanes to yield mechanized silica nanoparticles (MSNPs). In this Account, we chronicle the evolution of various MSNPs, which came about as a result of our decade-long collaboration, and discuss advances in the synthesis of novel hybrid SNPs and the various MIMs which have been attached to their surfaces. These MIMs can be designed in such a way that they either change shape

  5. Photoreactive azido-containing silica nanoparticle/polycation multilayers: durable superhydrophobic coating on cotton fabrics.

    PubMed

    Zhao, Yan; Xu, Zhiguang; Wang, Xungai; Lin, Tong

    2012-04-17

    In this study, we report the functionalization of silica nanoparticles with highly photoreactive phenyl azido groups and their utility as a negatively charged building block for layer-by-layer (LbL) electrostatic assembly to produce a stable silica nanoparticle coating. Azido-terminated silica nanoparticles were prepared by the functionalization of bare silica nanoparticles with 3-aminopropyltrimethoxysilane followed by the reaction with 4-azidobenzoic acid. The azido functionalization was confirmed by FTIR and XPS. Poly(allylamine hydrochloride) was also grafted with phenyl azido groups and used as photoreactive polycations for LbL assembly. For the photoreactive silica nanoparticle/polycation multilayers, UV irradiation can induce the covalent cross-linking within the multilayers as well as the anchoring of the multilayer film onto the organic substrate, through azido photochemical reactions including C-H insertion/abstraction reactions with surrounding molecules and dimerization of azido groups. Our results show that the stability of the silica nanoparticle/polycation multilayer film was greatly improved after UV irradiation. Combined with a fluoroalkylsilane post-treatment, the photoreactive LbL multilayers were used as a coating for superhydrophobic modification of cotton fabrics. Herein the LbL assembly method enables us to tailor the number of the coated silica nanoparticles through the assembly cycles. The superhydrophobicity of cotton fabrics was durable against acids, bases, and organic solvents, as well as repeated machine wash. Because of the unique azido photochemistry, the approach used here to anchor silica nanoparticles is applicable to almost any organic substrate. PMID:22462539

  6. Magnetic Silica-Supported Ruthenium Nanoparticles: An Efficient Catalyst for Transfer Hydrogenation of Carbonyl Compounds

    EPA Science Inventory

    One-pot synthesis of ruthenium nanoparticles on magnetic silica is described which involve the in situ generation of magnetic silica (Fe3O4@ SiO2) and ruthenium nano particles immobilization; the hydration of nitriles and transfer hydrogenation of carbonyl compounds occurs in hi...

  7. Silica nanoparticle stabilization of liquid crystalline lipid dispersions: impact on enzymatic digestion and drug solubilization.

    PubMed

    Bhatt, Achal B; Barnes, Timothy J; Prestidge, Clive A

    2015-01-01

    The high internal surface area and drug solubilizing capacity of liquid crystal lipids makes them promising oral drug delivery systems. Pluronic F127 is typically used to disperse highly viscous cubic liquid crystal lipids into cubosomes; however, such copolymers alter the internal structure and provide little control over enzymatic digestion. This study aimed to use hydrophilic silica nanoparticles to stabilize glyceryl monooleate (GMO) cubosomes prepared by ultrasonication. We investigate the influence of silica nanoparticles size and concentration on the physical (colloidal) and chemical (enzymatic digestion) stability, as well as in vitro solubilization of cinnarizine as a poorly soluble model drug. Silica stabilized nanostructured liquid crystal dispersions (120 nm to150 nm in diameter and zeta potentials of-30 mV to -60 mV) were successfully prepared with excellent long-term stability (<10% size change after 30 days). Silica stabilized GMO cubosomes demonstrated reduced enzymatic digestion compared to pluronic F127 stabilized cubosomes. This reduced digestion was attributed to a combination of adsorbed silica nanoparticles acting as a physical barrier and excess dispersed silica adsorbing/scavenging the lipase enzyme. Under simulated intestinal digestion conditions, silica stabilized GMO cubosomes showed a greater solubilization capacity for cinnarizine, which precipitated in non-crystalline form, in comparison to pure drug suspensions or pluronic F127 stabilized GMO cubosomes. Silica nanoparticle stabilized GMO liquid crystal dispersions are a promising oral delivery vehicle. PMID:25176029

  8. Cytotoxicity evaluation of silica nanoparticles using fish cell lines.

    PubMed

    Vo, Nguyen T K; Bufalino, Mary R; Hartlen, Kurtis D; Kitaev, Vladimir; Lee, Lucy E J

    2014-01-01

    Nanoparticles (NPs) have extensive industrial, biotechnological, and biomedical/pharmaceutical applications, leading to concerns over health risks to humans and biota. Among various types of nanoparticles, silica nanoparticles (SiO2 NPs) have become popular as nanostructuring, drug delivery, and optical imaging agents. SiO2 NPs are highly stable and could bioaccumulate in the environment. Although toxicity studies of SiO2 NPs to human and mammalian cells have been reported, their effects on aquatic biota, especially fish, have not been significantly studied. Twelve adherent fish cell lines derived from six species (rainbow trout, fathead minnow, zebrafish, goldfish, haddock, and American eel) were used to comparatively evaluate viability of cells by measuring metabolic impairment using Alamar Blue. Toxicity of SiO2 NPs appeared to be size-, time-, temperature-, and dose-dependent as well as tissue-specific. However, dosages greater than 100 μg/mL were needed to achieve 24 h EC50 values (effective concentrations needed to reduce cell viability by 50%). Smaller SiO2 NPs (16 nm) were relatively more toxic than larger sized ones (24 and 44 nm) and external lining epithelial tissue (skin, gills)-derived cells were more sensitive than cells derived from internal tissues (liver, brain, intestine, gonads) or embryos. Higher EC50 values were achieved when toxicity assessment was performed at higher incubation temperatures. These findings are in overall agreement with similar human and mouse cell studies reported to date. Thus, fish cell lines could be valuable for screening emerging contaminants in aquatic environments including NPs through rapid high-throughput cytotoxicity bioassays. PMID:24357037

  9. Apoptosis induction by silica nanoparticles mediated through reactive oxygen species in human liver cell line HepG2

    SciTech Connect

    Ahmad, Javed; Ahamed, Maqusood; Akhtar, Mohd Javed; Alrokayan, Salman A.; Siddiqui, Maqsood A.; Musarrat, Javed; Al-Khedhairy, Abdulaziz A.

    2012-03-01

    Silica nanoparticles are increasingly utilized in various applications including agriculture and medicine. In vivo studies have shown that liver is one of the primary target organ of silica nanoparticles. However, possible mechanisms of hepatotoxicity caused by silica nanoparticles still remain unclear. In this study, we explored the reactive oxygen species (ROS) mediated apoptosis induced by well-characterized 14 nm silica nanoparticles in human liver cell line HepG2. Silica nanoparticles (25–200 μg/ml) induced a dose-dependent cytotoxicity in HepG2 cells. Silica nanoparticles were also found to induce oxidative stress in dose-dependent manner indicated by induction of ROS and lipid peroxidation and depletion of glutathione (GSH). Quantitative real-time PCR and immunoblotting results showed that both the mRNA and protein expressions of cell cycle checkpoint gene p53 and apoptotic genes (bax and caspase-3) were up-regulated while the anti-apoptotic gene bcl-2 was down-regulated in silica nanoparticles treated cells. Moreover, co-treatment of ROS scavenger vitamin C significantly attenuated the modulation of apoptotic markers along with the preservation of cell viability caused by silica nanoparticles. Our data demonstrated that silica nanoparticles induced apoptosis in human liver cells, which is ROS mediated and regulated through p53, bax/bcl-2 and caspase pathways. This study suggests that toxicity mechanisms of silica nanoparticles should be further investigated at in vivo level. -- Highlights: ► We explored the mechanisms of toxicity caused by silica NPs in human liver HepG2 cells. ► Silica NPs induced a dose-dependent cytotoxicity in HepG2 cells. ► Silica NPs induced ROS generation and oxidative stress in a dose-dependent manner. ► Silica NPs were also modulated apoptosis markers both at mRNA and protein levels. ► ROS mediated apoptosis induced by silica NPs was preserved by vitamin C.

  10. Preparation of Silica Nanoparticles Through Microwave-assisted Acid-catalysis

    PubMed Central

    Lovingood, Derek D.; Owens, Jeffrey R.; Seeber, Michael; Kornev, Konstantin G.; Luzinov, Igor

    2013-01-01

    Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan δ solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials' morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by Stöber's methods, which have smooth surfaces. PMID:24379052

  11. Wettability alteration properties of fluorinated silica nanoparticles in liquid-loaded pores: An atomistic simulation

    NASA Astrophysics Data System (ADS)

    Sepehrinia, Kazem; Mohammadi, Aliasghar

    2016-05-01

    Control over the wettability of reservoir rocks is of crucial importance for enhancing oil and gas recovery. In order to develop chemicals for controlling the wettability of reservoir rocks, we present a study of functionalized silica nanoparticles as candidates for wettability alteration and improved gas recovery applications. In this paper, properties of fluorinated silica nanoparticles were investigated in water or decane-loaded pores of mineral silica using molecular dynamics simulation. Trifluoromethyl groups as water and oil repellents were placed on the nanoparticles. Simulating a pore in the presence of trapped water or decane molecules leads to liquid bridging for both of the liquids. Adsorption of nanoparticles on the pore wall reduces the density of liquid molecules adjacent to the wall. The density of liquid molecules around the nanoparticles decreases significantly with increasing the number of trifluoromethyl groups on the nanoparticles' surfaces. An increased hydrophobicity of the pore wall was observed in the presence of adsorbed fluorinated silica nanoparticles. Also, it is observed that increasing the number of the trifluoromethyl groups results in weakening of liquid bridges. Moreover, the free energy of adsorption on mineral surface was evaluated to be more favorable than that of aggregation of nanoparticles, which suggests nanoparticles adsorb preferably on mineral surface.

  12. Size dependent fractal aggregation mediated through surfactant in silica nanoparticle solution

    NASA Astrophysics Data System (ADS)

    Kumar, Sugam; Aswal, V. K.; Kohlbrecher, J.

    2012-06-01

    Small-angle neutron scattering (SANS) has been used to study aggregation of anionic silica nanoparticles in presence of cationic surfactant (DTAB) in aqueous solution. The measurements were carried out for different sizes of nanoparticles (8.2, 16.4 and 26.4 nm) at fixed (1 wt%) nanoparticles and surfactant concentration. It is found that the adsorption of surfactant micelles on the silica nanoparticles leads to the aggregation of nanoparticles, which is characterized by a fractal structure. The number of adsorbed micelles on nanoparticle increases from 7 to 152 with the increase in the size of the nanoparticle from 8.2 to 26.4 nm, whereas interestingly the fractal dimension remains same. The aggregate morphology in these systems is expected to be governed by the diffusion limited aggregation.

  13. Complete magnesiothermic reduction reaction of vertically aligned mesoporous silica channels to form pure silicon nanoparticles

    PubMed Central

    Kim, Kyoung Hwan; Lee, Dong Jin; Cho, Kyeong Min; Kim, Seon Joon; Park, Jung-Ki; Jung, Hee-Tae

    2015-01-01

    Owing to its simplicity and low temperature conditions, magnesiothermic reduction of silica is one of the most powerful methods for producing silicon nanostructures. However, incomplete reduction takes place in this process leaving unconverted silica under the silicon layer. This phenomenon limits the use of this method for the rational design of silicon structures. In this effort, a technique that enables complete magnesiothermic reduction of silica to form silicon has been developed. The procedure involves magnesium promoted reduction of vertically oriented mesoporous silica channels on reduced graphene oxides (rGO) sheets. The mesopores play a significant role in effectively enabling magnesium gas to interact with silica through a large number of reaction sites. Utilizing this approach, highly uniform, ca. 10 nm sized silicon nanoparticles are generated without contamination by unreacted silica. The new method for complete magnesiothermic reduction of mesoporous silica approach provides a foundation for the rational design of silicon structures. PMID:25757800

  14. On the stabilization of gold nanoparticles over silica-based magnetic supports modified with organosilanes.

    PubMed

    Oliveira, Rafael L; Zanchet, Daniela; Kiyohara, Pedro K; Rossi, Liane M

    2011-04-11

    The immobilization of gold nanoparticles (Au NPs) on silica is made possible by the functionalization of the silica surfaces with organosilanes. Au NPs could only be stabilized and firmly attached to silica-support surfaces that were previously modified with amino groups. Au NPs could not be stabilized on bare silica surfaces and most of the NPs were then found in the solution. The metal-support interactions before and after the Au NP formation, observed by X-ray absorption fine structure spectroscopy (XAFS), indicate a stronger interaction of gold(III) ions with amino-modified silica surfaces than with the silanol groups in bare silica. An amino-modified, silica-based, magnetic support was used to prepare an active Au NP catalyst for the chemoselective oxidation of alcohols, a reaction of great interest for the fine chemical industry. PMID:21360597

  15. Complete magnesiothermic reduction reaction of vertically aligned mesoporous silica channels to form pure silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Kim, Kyoung Hwan; Lee, Dong Jin; Cho, Kyeong Min; Kim, Seon Joon; Park, Jung-Ki; Jung, Hee-Tae

    2015-03-01

    Owing to its simplicity and low temperature conditions, magnesiothermic reduction of silica is one of the most powerful methods for producing silicon nanostructures. However, incomplete reduction takes place in this process leaving unconverted silica under the silicon layer. This phenomenon limits the use of this method for the rational design of silicon structures. In this effort, a technique that enables complete magnesiothermic reduction of silica to form silicon has been developed. The procedure involves magnesium promoted reduction of vertically oriented mesoporous silica channels on reduced graphene oxides (rGO) sheets. The mesopores play a significant role in effectively enabling magnesium gas to interact with silica through a large number of reaction sites. Utilizing this approach, highly uniform, ca. 10 nm sized silicon nanoparticles are generated without contamination by unreacted silica. The new method for complete magnesiothermic reduction of mesoporous silica approach provides a foundation for the rational design of silicon structures.

  16. The synthesis and application of two mesoporous silica nanoparticles as drug delivery system with different shape

    NASA Astrophysics Data System (ADS)

    Wang, Jiayi; Wang, Zhuyuan; Chen, Hui; Zong, Shenfei; Cui, Yiping

    2015-05-01

    Mesoporous silica nanospheres(MSNSs) have been obtained utilizing the conventional reverse micelles synthesis method while the mesoporous silica nanorods(MSNRs) have been acquired by means of changing certain parameters. Afterwards, the prepared mesoporous silica nanospheres and nanorods were used as drug carriers to load and release the classical cancer therapeutic drug—DOX. According to the absorption spectra, the encapsulation efficiency of the mesoporous silica nanospheres is almost as high as that of the nanospheres. Different from the familiar encapsulation efficiency, the release characteristic curves of the mesoporous silica nanospheres and nanorods possessed certain differences during the release process. Finally incellular fluorescence imaging was achieved to observe the endocytosis of the mesoporous silica materials. Our results show that although both of the two kinds of nanoparticles possess favourable properties for loading and releasing drugs, the mesoporous silica nanospheres perform better in dispersity and controlled release than the nanorods, which probably endow them the potential as incellular drug delivery system.

  17. Uniform dispersion of lanthanum hexaboride nanoparticles in a silica thin film: synthesis and optical properties.

    PubMed

    Jiang, Fei; Leong, Yee-Kwong; Saunders, Martine; Martyniuk, Mariusz; Faraone, Lorenzo; Keating, Adrian; Dell, John M

    2012-11-01

    Silica thin films containing uniformly dispersed lanthanum hexaboride (LaB₆) nanoparticles have been prepared by spin-coating a sol-gel silica solution containing cetyltrimethyl ammonium bromide (CTAB)-stabilized LaB₆ nanoparticles onto a glass substrate followed by a standard heat treatment. The production of this thin film involved three steps: (i) a CTAB-stabilized LaB₆ nanoparticle dispersion was prepared in water and then dried, (ii) the dried nanoparticles were redispersed in a small amount of water and mixed with tetraethoxyorthosilane (TEOS), ethanol, and a little acid to initiate the sol-gel reaction, and (iii) this reaction mixture was spun to produce a thin film and then was annealed. A range of techniques such as zeta potential, laser sizing, energy-filtered transmission electron microscopy (EFTEM), scanning TEM (STEM), scanning electron microscopy (SEM), and energy dispersive X-ray spectrum (EDS) were employed to characterize the particle's size, elemental composition, and stability and the optical properties of silica thin films with LaB₆ nanoparticles. On the basis of the optical transmittance and reflectance spectra of an annealed silica thin film with LaB₆ nanoparticles, the annealed thin films clearly showed positive absorption of radiation in the near infrared (NIR) region meeting a main objective of this study. A potential optical micro-electromechanical sensing system in the NIR range can be realized on the basis of this silica thin film with LaB₆ nanoparticles. PMID:23057614

  18. Surface functionalized mesoporous silica nanoparticles for intracellular drug delivery

    NASA Astrophysics Data System (ADS)

    Vivero-Escoto, Juan Luis

    Mesoporous silica nanoparticles (MSNs) are a highly promising platform for intracellular controlled release of drugs and biomolecules. Despite that the application of MSNs in the field of intracellular drug delivery is still at its infancy very exciting breakthroughs have been achieved in the last years. A general review of the most recent progress in this area of research is presented, including a description of the latest findings on the pathways of entry into live mammalian cells together with the intracellular trafficking, a summary on the contribution of MSNs to the development of site-specific drug delivery systems, a report on the biocompatibility of this material in vitro andin vivo, and a discussion on the most recent breakthroughs in the synthesis and application of stimuli-responsive mesoporous silica-based delivery vehicles. A gold nanoparticles (AuNPs)-capped MSNs-based intracellular photoinduced drug delivery system (PR-AuNPs-MSNs) for the controlled release of anticancer drug inside of human fibroblast and liver cells was synthesized and characterized. We found that the mesoporous channels of MSNs could be efficiently capped by the photoresponsive AuNPs without leaking the toxic drug, paclitaxel, inside of human cells. Furthermore, we demonstrated that the cargo-release property of this PR-AuNPs-MSNs system could be easily photo-controlled under mild and biocompatible conditions in vitro. In collaboration with Renato Mortera (a visiting student from Italy), a MSNs based intracellular delivery system for controlled release of cell membrane impermeable cysteine was developed. A large amount of cysteine molecules were covalently attached to the silica surface of MSNs through cleavable disulfide linkers. These cysteine-containing nanoparticles were efficiently endocytosed by human cervical cancer cells HeLa. These materials exhibit 450 times higher cell growth inhibition capability than that of the conventional N-acetylcysteine prodrug. The ability to

  19. A reversible light-operated nanovalve on mesoporous silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Tarn, Derrick; Ferris, Daniel P.; Barnes, Jonathan C.; Ambrogio, Michael W.; Stoddart, J. Fraser; Zink, Jeffrey I.

    2014-02-01

    Two azobenzene α-cyclodextrin based nanovalves are designed, synthesized and assembled on mesoporous silica nanoparticles. Under aqueous conditions, the cyclodextrin cap is tightly bound to the azobenzene moiety and capable of holding back loaded cargo molecules. Upon irradiation with a near-UV light laser, trans to cis-photoisomerization of azobenzene initiates a dethreading process, which causes the cyclodextrin cap to unbind followed by the release of cargo. The addition of a bulky stopper to the end of the stalk allows this design to be reversible; complete dethreading of cyclodextrin as a result of unbinding with azobenzene is prevented as a consequence of steric interference. As a result, thermal relaxation of cis- to trans-azobenzene allows for the rebinding of cyclodextrin and resealing of the nanopores, a process which entraps the remaining cargo. Two stalks were designed with different lengths and tested with alizarin red S and propidium iodide. No cargo release was observed prior to light irradiation, and the system was capable of multiuse. On/off control was also demonstrated by monitoring the release of cargo when the light stimulus was applied and removed, respectively.Two azobenzene α-cyclodextrin based nanovalves are designed, synthesized and assembled on mesoporous silica nanoparticles. Under aqueous conditions, the cyclodextrin cap is tightly bound to the azobenzene moiety and capable of holding back loaded cargo molecules. Upon irradiation with a near-UV light laser, trans to cis-photoisomerization of azobenzene initiates a dethreading process, which causes the cyclodextrin cap to unbind followed by the release of cargo. The addition of a bulky stopper to the end of the stalk allows this design to be reversible; complete dethreading of cyclodextrin as a result of unbinding with azobenzene is prevented as a consequence of steric interference. As a result, thermal relaxation of cis- to trans-azobenzene allows for the rebinding of cyclodextrin and

  20. Processing pathway dependence of amorphous silica nanoparticle toxicity: colloidal vs pyrolytic.

    PubMed

    Zhang, Haiyuan; Dunphy, Darren R; Jiang, Xingmao; Meng, Huan; Sun, Bingbing; Tarn, Derrick; Xue, Min; Wang, Xiang; Lin, Sijie; Ji, Zhaoxia; Li, Ruibin; Garcia, Fred L; Yang, Jing; Kirk, Martin L; Xia, Tian; Zink, Jeffrey I; Nel, Andre; Brinker, C Jeffrey

    2012-09-26

    We have developed structure/toxicity relationships for amorphous silica nanoparticles (NPs) synthesized through low-temperature colloidal (e.g., Stöber silica) or high-temperature pyrolysis (e.g., fumed silica) routes. Through combined spectroscopic and physical analyses, we have determined the state of aggregation, hydroxyl concentration, relative proportion of strained and unstrained siloxane rings, and potential to generate hydroxyl radicals for Stöber and fumed silica NPs with comparable primary particle sizes (16 nm in diameter). On the basis of erythrocyte hemolytic assays and assessment of the viability and ATP levels in epithelial and macrophage cells, we discovered for fumed silica an important toxicity relationship to postsynthesis thermal annealing or environmental exposure, whereas colloidal silicas were essentially nontoxic under identical treatment conditions. Specifically, we find for fumed silica a positive correlation of toxicity with hydroxyl concentration and its potential to generate reactive oxygen species (ROS) and cause red blood cell hemolysis. We propose fumed silica toxicity stems from its intrinsic population of strained three-membered rings (3MRs) along with its chainlike aggregation and hydroxyl content. Hydrogen-bonding and electrostatic interactions of the silanol surfaces of fumed silica aggregates with the extracellular plasma membrane cause membrane perturbations sensed by the Nalp3 inflammasome, whose subsequent activation leads to secretion of the cytokine IL-1β. Hydroxyl radicals generated by the strained 3MRs in fumed silica, but largely absent in colloidal silicas, may contribute to the inflammasome activation. Formation of colloidal silica into aggregates mimicking those of fumed silica had no effect on cell viability or hemolysis. This study emphasizes that not all amorphous silicas are created equal and that the unusual toxicity of fumed silica compared to that of colloidal silica derives from its framework and surface

  1. Processing pathway dependence of amorphous silica nanoparticle toxicity - colloidal versus pyrolytic

    PubMed Central

    Zhang, Haiyuan; Dunphy, Darren R.; Jiang, Xingmao; Meng, Huan; Sun, Bingbing; Tarn, Derrick; Xue, Min; Wang, Xiang; Lin, Sijie; Ji, Zhaoxia; Li, Ruibin; Garcia, Fred L.; Yang, Jing; Kirk, Martin L.; Xia, Tian; Zink, Jeffrey I; Nel, Andre; Brinker, C. Jeffrey

    2012-01-01

    We have developed structure/toxicity relationships for amorphous silica nanoparticles (NPs) synthesized through low temperature, colloidal (e.g. Stöber silica) or high temperature pyrolysis (e.g. fumed silica) routes. Through combined spectroscopic and physical analyses, we have determined the state of aggregation, hydroxyl concentration, relative proportion of strained and unstrained siloxane rings, and potential to generate hydroxyl radicals for Stöber and fumed silica NPs with comparable primary particle sizes (16-nm in diameter). Based on erythrocyte hemolytic assays and assessment of the viability and ATP levels in epithelial and macrophage cells, we discovered for fumed silica an important toxicity relationship to post-synthesis thermal annealing or environmental exposure, whereas colloidal silicas were essentially non-toxic under identical treatment conditions. Specifically, we find for fumed silica a positive correlation of toxicity with hydroxyl concentration and its potential to generate reactive oxygen species (ROS) and cause red blood cell hemolysis. We propose fumed silica toxicity stems from its intrinsic population of strained three-membered rings (3MRs) along with its chain-like aggregation and hydroxyl content. Hydrogen-bonding and electrostatic interactions of the silanol surfaces of fumed silica aggregates with the extracellular plasma membrane cause membrane perturbations sensed by the Nalp3 inflammasome, whose subsequent activation leads to secretion of the cytokine IL-1β. Hydroxyl radicals generated by the strained 3MRs in fumed silica but largely absent in colloidal silicas may contribute to the inflammasome activation. Formation of colloidal silica into aggregates mimicking those of fumed silica had no effect on cell viability or hemolysis. This study emphasizes that not all amorphous silica is created equal and that the unusual toxicity of fumed silica compared to colloidal silica derives from its framework and surface chemistry along

  2. Synthesis of superparamagnetic silica-coated magnetite nanoparticles for biomedical applications

    SciTech Connect

    Kaur, Navjot Chudasama, Bhupendra

    2015-05-15

    Multifunctional superparamagnetic iron oxide nanoparticles (SPIONs) coated with silica are widely researched for biomedical applications such as magnetic resonance imaging, tissue repair, cell separation, hyperthermia, drug delivery, etc. In this article synthesis of magnetite (Fe{sub 3}O{sub 4}) nanoparticles and their coating with SiO{sub 2} is reported. Fe{sub 3}O{sub 4} nanoparticles were synthesized by chemical co-precipitation and it was coated with silica by hydrolysis and condensation of tetraethylorthosilicate. XRD, FTIR, TEM and VSM techniques were used to characterize bare and coated nanoparticles. Results indicated that the average size of SPIONS was 8.4 nm. X-ray diffraction patterns of silica coated SPIONS were identical to that of SPIONS confirming the inner spinal structure of SPIONS. FTIR results confirmed the binding of silica with the magnetite and the formation of the silica shell around the magnetite core. Magnetic properties of SPIONS and silica coated SPIONS are determined by VSM. They are superparamagnetic. The major conclusion drawn from this study is that the synthesis route yields stable, non-aggregated magnetite-silica core-shell nanostructures with tailored morphology and excellent magnetic properties.

  3. Synthesis of superparamagnetic silica-coated magnetite nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Kaur, Navjot; Chudasama, Bhupendra

    2015-05-01

    Multifunctional superparamagnetic iron oxide nanoparticles (SPIONs) coated with silica are widely researched for biomedical applications such as magnetic resonance imaging, tissue repair, cell separation, hyperthermia, drug delivery, etc. In this article synthesis of magnetite (Fe3O4) nanoparticles and their coating with SiO2 is reported. Fe3O4 nanoparticles were synthesized by chemical co-precipitation and it was coated with silica by hydrolysis and condensation of tetraethylorthosilicate. XRD, FTIR, TEM and VSM techniques were used to characterize bare and coated nanoparticles. Results indicated that the average size of SPIONS was 8.4 nm. X-ray diffraction patterns of silica coated SPIONS were identical to that of SPIONS confirming the inner spinal structure of SPIONS. FTIR results confirmed the binding of silica with the magnetite and the formation of the silica shell around the magnetite core. Magnetic properties of SPIONS and silica coated SPIONS are determined by VSM. They are superparamagnetic. The major conclusion drawn from this study is that the synthesis route yields stable, non-aggregated magnetite-silica core-shell nanostructures with tailored morphology and excellent magnetic properties.

  4. Silica nanoparticles coencapsulating gadolinium oxide and horseradish peroxidase for imaging and therapeutic applications

    PubMed Central

    Gupta, Nikesh; Shrivastava, Anju; Sharma, Rakesh K

    2012-01-01

    Mesoporous silica nanoparticles coencapsulating gadolinium oxide and horseradish peroxidase (HRP) have been synthesized in the aqueous core of sodium bis-(2-ethylhexyl) sulfosuccinate (AOT)–hexane–water reverse micelle. The average diameter of these silica particles is around 25 nm and the particles are spherical and highly monodispersed as depicted using transmission electron microscopy. The entrapment efficiency of HRP was found to be as high as 95%. Practically, the entrapped enzyme shows zero leachability up to 90 days. The enzyme entrapped in these silica nanoparticles follows Michaelis–Menten kinetics. Peroxidase entrapped in silica nanoparticles shows higher stability towards temperature and pH change as compared to free enzymes. The gadolinium oxide-doped silica nanoparticles are paramagnetic as observed from the nuclear magnetic resonance line-broadening effect on the proton spectrum of the surrounding water molecule. The entrapped enzyme, HRP, has been used to convert a benign prodrug, indole-3-acetic acid (IAA), to a toxic oxidized product and its toxic effect has been tested on cancerous cell lines through thiazolyl blue tetrazolium blue (MTT) assay. In vitro studies on different cancerous cell lines show that the enzyme has been entrapped and retains its activity inside the silica nanoparticles. IAA alone has no cytotoxic effect and it becomes active only after oxidative decarboxylation by HRP. PMID:23233799

  5. Silica nanoparticles coencapsulating gadolinium oxide and horseradish peroxidase for imaging and therapeutic applications.

    PubMed

    Gupta, Nikesh; Shrivastava, Anju; Sharma, Rakesh K

    2012-01-01

    Mesoporous silica nanoparticles coencapsulating gadolinium oxide and horseradish peroxidase (HRP) have been synthesized in the aqueous core of sodium bis-(2-ethylhexyl) sulfosuccinate (AOT)-hexane-water reverse micelle. The average diameter of these silica particles is around 25 nm and the particles are spherical and highly monodispersed as depicted using transmission electron microscopy. The entrapment efficiency of HRP was found to be as high as 95%. Practically, the entrapped enzyme shows zero leachability up to 90 days. The enzyme entrapped in these silica nanoparticles follows Michaelis-Menten kinetics. Peroxidase entrapped in silica nanoparticles shows higher stability towards temperature and pH change as compared to free enzymes. The gadolinium oxide-doped silica nanoparticles are paramagnetic as observed from the nuclear magnetic resonance line-broadening effect on the proton spectrum of the surrounding water molecule. The entrapped enzyme, HRP, has been used to convert a benign prodrug, indole-3-acetic acid (IAA), to a toxic oxidized product and its toxic effect has been tested on cancerous cell lines through thiazolyl blue tetrazolium blue (MTT) assay. In vitro studies on different cancerous cell lines show that the enzyme has been entrapped and retains its activity inside the silica nanoparticles. IAA alone has no cytotoxic effect and it becomes active only after oxidative decarboxylation by HRP. PMID:23233799

  6. Hyaluronan degrading silica nanoparticles for skin cancer therapy

    NASA Astrophysics Data System (ADS)

    Scodeller, P.; Catalano, P. N.; Salguero, N.; Duran, H.; Wolosiuk, A.; Soler-Illia, G. J. A. A.

    2013-09-01

    We report the first nanoformulation of Hyaluronidase (Hyal) and its enhanced adjuvant effect over the free enzyme. Hyaluronic acid (HA) degrading enzyme Hyal was immobilized on 250 nm silica nanoparticles (SiNP) maintaining specific activity of the enzyme via the layer-by-layer self-assembly technique. This process was characterized by dynamic light scattering (DLS), zeta potential, infrared and UV-Vis spectroscopy, transmission electron microscopy (TEM) and enzymatic activity measurements. The nanoparticles were tested in vivo as adjuvants of carboplatin (CP), peritumorally injected in A375 human melanoma bearing mice and compared with the non-immobilized enzyme, on the basis of equal enzymatic activity. Alcian Blue staining of A375 tumors indicated large overexpression of hyaluronan. At the end of the experiment, tumor volume reduction with SiNP-immobilized Hyal was significantly enhanced compared to non-immobilized Hyal. Field emission scanning electron microscopy (FE-SEM) images together with energy dispersive X-ray spectroscopy (EDS) spectra confirmed the presence of SiNP on the tumor. We mean a proof of concept: this extracellular matrix (ECM) degrading enzyme, immobilized on SiNP, is a more effective local adjuvant of cancer drugs than the non-immobilized enzyme. This could prove useful in future therapies using other or a combination of ECM degrading enzymes.We report the first nanoformulation of Hyaluronidase (Hyal) and its enhanced adjuvant effect over the free enzyme. Hyaluronic acid (HA) degrading enzyme Hyal was immobilized on 250 nm silica nanoparticles (SiNP) maintaining specific activity of the enzyme via the layer-by-layer self-assembly technique. This process was characterized by dynamic light scattering (DLS), zeta potential, infrared and UV-Vis spectroscopy, transmission electron microscopy (TEM) and enzymatic activity measurements. The nanoparticles were tested in vivo as adjuvants of carboplatin (CP), peritumorally injected in A375 human

  7. Double-Layer Magnetic Nanoparticle-Embedded Silica Particles for Efficient Bio-Separation

    PubMed Central

    Kang, Homan; Cho, Hong-Jun; Park, Sung-Jun; Yang, Jin-Kyoung; Kim, Sehoon; Kim, Hyung-Mo; Jun, Bong-Hyun; Lee, Yoon-Sik

    2015-01-01

    Superparamagnetic Fe3O4 nanoparticles (NPs) based nanomaterials have been exploited in various biotechnology fields including biomolecule separation. However, slow accumulation of Fe3O4 NPs by magnets may limit broad applications of Fe3O4 NP-based nanomaterials. In this study, we report fabrication of Fe3O4 NPs double-layered silica nanoparticles (DL MNPs) with a silica core and highly packed Fe3O4 NPs layers. The DL MNPs had a superparamagnetic property and efficient accumulation kinetics under an external magnetic field. Moreover, the magnetic field-exposed DL MNPs show quantitative accumulation, whereas Fe3O4 NPs single-layered silica nanoparticles (SL MNPs) and silica-coated Fe3O4 NPs produced a saturated plateau under full recovery of the NPs. DL MNPs are promising nanomaterials with great potential to separate and analyze biomolecules. PMID:26599084

  8. Effect of catalyst concentration on size, morphology and optical properties of silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Arora, Ekta; Ritu, Kumar, Sacheen; Kumar, Dinesh

    2016-05-01

    Today, nanomaterials play a key role in various fields such as electronics, aerospace, pharmaceuticals and biomedical because of their unique physical, chemical and biological properties which are different from bulk materials. Nano sized silica particles have gained the prominent position in scientific research and have wide applications. The sol-gel method is the best method to synthesize silica nanoparticles because of its potential to produce monodispersed with narrow size distribution at mild conditions. The silica nanoparticles were obtained by hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol act as solvent. The synthesized nanoparticles were characterized by Field Emission Scanning electron Microscope (FE-SEM), UV Spectrometer. The smallest size of silica particles is around 150nm examined by using FE-SEM. The optical properties and band structure was analyzed using UV-visible spectroscopy which is found to be increase by reducing the size of particles. Concentration effect of catalyst on the size, morphology and optical properties were analyzed.

  9. Preparation and characterization of surface-engineered coarse microcrystalline cellulose through dry coating with silica nanoparticles.

    PubMed

    Zhou, Qun; Shi, Limin; Chattoraj, Sayantan; Sun, Changquan Calvin

    2012-11-01

    A popular grade of microcrystalline cellulose (MCC) exhibits excellent tabletability, but marginal flowability for high-speed tableting operations. Accordingly, an enhancement in flowability, while preserving its tabletability, will make it a more useful excipient in pharmaceutical tablet formulations, especially for the direct compression process. In this work, we show that surface coating by silica nanoparticles, using either a dry comilling process or simple mechanical blending, is a valid strategy for achieving the goal. The effects of milling intensity, either the number of comilling cycles or blending time, and silica loading level have been evaluated. Results show that surface deposition of 0.1% silica nanoparticles substantially improves the flowability of this grade of MCC while preserving a significant portion of its tabletability. Higher silica loading leads to better flowability, but at the cost of reduced tabletability. However, even up to 2.0% silica deposition, its tabletability remains superior. PMID:22927169

  10. Characterizing structural and vibrational properties of nanoparticles embedded in silica with XAS, SAXS and auxiliary techniques

    NASA Astrophysics Data System (ADS)

    Araujo, Leandro L.; Kluth, Patrick; Giulian, Raquel; Sprouster, David J.; Johannessen, Bernt; Foran, Garry J.; Cookson, David J.; Ridgway, Mark C.

    2009-01-01

    Synchrotron-based techniques were combined with conventional analysis methods to probe in detail the structural and vibrational properties of nanoparticles grown in a silica matrix by ion implantation and thermal annealing, as well as the evolution of such properties as a function of nanoparticle size. This original approach was successfully applied for several elemental nanoparticles (Au, Co, Cu, Ge, Pt) and the outcomes for Ge are reported here, illustrating the power of this combined methodology. The thorough analysis of XANES, EXAFS, SAXS, TEM and Raman data for Ge nanoparticles with mean diameters between 4 and 9 nm revealed that the peculiar properties of embedded Ge nanoparticles, like the existence of amorphous Ge layers between the silica matrix and the crystalline nanoparticle core, are strongly dependent on particle size and mainly governed by the variation in the surface area-to-volume ratio. Such detailed information provides valuable input for the efficient planning of technological applications.

  11. Codelivery of anticancer drugs and siRNA by mesoporous silica nanoparticles.

    PubMed

    Hanafi-Bojd, Mohammad Yahya; Ansari, Legha; Malaekeh-Nikouei, Bizhan

    2016-09-01

    The most common method for cancer treatment is chemotherapy. Multidrug resistance (MDR) is one of the major obstacles in chemotherapeutic treatment of many human cancers. One strategy to overcome this challenge is the delivery of anticancer drugs and siRNA simultaneously using nanoparticles. Mesoporous silica nanoparticles are one of the most popular nanoparticles for cargo delivery because of their intrinsic porosity. This paper highlights recent advances in codelivery of chemotherapeutic and siRNA with mesoporous silica nanoparticles for cancer therapy. In addition, synthesis and functionalization approaches of these nanoparticles are summarized. This review presents insight into the utilization of nanoparticles and combination therapy to achieve more promising results in chemotherapy. PMID:27582236

  12. Characterizing structural and vibrational properties of nanoparticles embedded in silica with XAS, SAXS and auxiliary techniques

    SciTech Connect

    Araujo, Leandro L.; Kluth, Patrick; Giulian, Raquel; Sprouster, David J.; Ridgway, Mark C.; Johannessen, Bernt; Foran, Garry J.; Cookson, David J.

    2009-01-29

    Synchrotron-based techniques were combined with conventional analysis methods to probe in detail the structural and vibrational properties of nanoparticles grown in a silica matrix by ion implantation and thermal annealing, as well as the evolution of such properties as a function of nanoparticle size. This original approach was successfully applied for several elemental nanoparticles (Au, Co, Cu, Ge, Pt) and the outcomes for Ge are reported here, illustrating the power of this combined methodology. The thorough analysis of XANES, EXAFS, SAXS, TEM and Raman data for Ge nanoparticles with mean diameters between 4 and 9 nm revealed that the peculiar properties of embedded Ge nanoparticles, like the existence of amorphous Ge layers between the silica matrix and the crystalline nanoparticle core, are strongly dependent on particle size and mainly governed by the variation in the surface area-to-volume ratio. Such detailed information provides valuable input for the efficient planning of technological applications.

  13. Mechanized Silica Nanoparticles: A New Frontier in Theranostic Nanomedicine

    NASA Astrophysics Data System (ADS)

    Ambrogio, Michael William

    Nanotechnology has emerged as one of humanity's most promising prospects for addressing a plethora of significant challenges facing society. One of these challenges is the effective treatment of cancer, and while cancer treatment has enjoyed many significant advances over the past several years, it is by no means perfect, and still suffers from many drawbacks. For example, although there are several drugs on the market that can kill cancer tissue quite effectively, these drugs are often non-selective, resulting in a large amount of healthy tissue being killed as well. When healthy tissue is destroyed, it results in many of the horrendous side-effects that we typically associate with cancer treatment, such as hair loss and extreme nausea. The use of selective drug delivery vehicles has the potential to reduce these side effects significantly, since they are able to deliver drugs directly to the tumor site, leaving healthy tissue intact. As a result, the use of sophisticated delivery platforms - mechanized silica nanoparticles (MSNPs) in particular - has attracted attention during the past decade, with researchers shifting their focus towards devising ways to deliver therapeutic and / or diagnostic agents, and away from developing new drug candidates. The advancement of these MSNP delivery systems is featured in this Dissertation, and highlights the fabrication of several new MSNPs, as well as biological experiments that have been initiated on these systems.

  14. Dual surface plasmon resonances in Ni nanoparticles in silica

    SciTech Connect

    Majhi, Jayanta K.; Kuiri, Probodh K.

    2015-06-24

    We report the observations of two broad absorption bands (at ∼3.5 and ∼6.0 eV) in the optical absorption (OA) spectra of Ni nanoparticles (NPs) in silica. For the calculations of the OA spectra, Maxwell-Garnett type effective medium theory has been used with NP radii in the range of 1 – 50 nm. The peak positions of both the OA bands have been found to shift towards higher energy (blue-shift) with decrease in NP radius. In addition, the OA spectra are found to more sensitive for smaller NPs as compare to larger NPs. These observations are argued as due to the confinement of the mean free path of free electrons in Ni NPs. Based on this, we conclude that the observed OA bands are due to the surface plasmon resonance (SPR) absorptions irrespective of the satisfaction of the criteria of the SPR conditions, thus resolving the unclear understanding of the appearance of two absorption bands in Ni NPs.

  15. Hydrophobic Silica Nanoparticles Induce Gel Phases in Phospholipid Monolayers.

    PubMed

    Orsi, Davide; Rimoldi, Tiziano; Guzmán, Eduardo; Liggieri, Libero; Ravera, Francesca; Ruta, Beatrice; Cristofolini, Luigi

    2016-05-17

    Silica nanoparticles (SiNP) can be incorporated in phospholipid layers to form hybrid organic-inorganic bidimensional mesostructures. Controlling the dynamics in these mesostructures paves the way to high-performance drug-delivery systems. Depending on the different hydrophobicity/hydrophilicity of SiNP, recent X-ray reflectivity experiments have demonstrated opposite structural effects. While these are reasonably well understood, less is known about the effects on the dynamics, which in turn determine molecular diffusivity and the possibility of drug release. In this work we characterize the dynamics of a mixed Langmuir layer made of phospholipid and hydrophobic SiNP. We combine X-ray photon correlation spectroscopy and epifluorescence discrete Fourier microscopy to cover more than 2 decades of Q-range (0.3-80 μm(-1)). We obtain evidence for the onset of an arrested state characterized by intermittent stress-relaxation rearrangement events, corresponding to a gel dominated by attractive interactions. We compare this with our previous results from phospholipid/hydrophilic SiNP films, which show an arrested glassy phase of repulsive disks. PMID:27133453

  16. Near Infrared Light-Powered Janus Mesoporous Silica Nanoparticle Motors.

    PubMed

    Xuan, Mingjun; Wu, Zhiguang; Shao, Jingxin; Dai, Luru; Si, Tieyan; He, Qiang

    2016-05-25

    We describe fuel-free, near-infrared (NIR)-driven Janus mesoporous silica nanoparticle motors (JMSNMs) with diameters of 50, 80, and 120 nm. The Janus structure of the JMSNMs is generated by vacuum sputtering of a 10 nm Au layer on one side of the MSNMs. Upon exposure to an NIR laser, a localized photothermal effect on the Au half-shells results in the formation of thermal gradients across the JMSNMs; thus, the generated self-thermophoresis can actively drive the nanomotors to move at an ultrafast speed, for instance, up to 950 body lengths/s for 50 nm JMSNMs under an NIR laser power of 70.3 W/cm(2). The reversible "on/off" motion of the JMSNMs and their directed movement along the light gradient can be conveniently modulated by a remote NIR laser. Moreover, dynamic light scattering measurements are performed to investigate the coexisting translational and rotational motion of the JMSNMs in the presence of both self-thermophoretic forces and strong Brownian forces. These NIR-powered nanomotors demonstrate a novel strategy for overcoming the necessity of chemical fuels and exhibit a significant improvement in the maneuverability of nanomotors while providing potential cargo transportation in a biofriendly manner. PMID:27152728

  17. Effective water disinfection using silver nanoparticle containing silica beads

    NASA Astrophysics Data System (ADS)

    Quang, Dang Viet; Sarawade, Pradip B.; Jeon, Sun Jeong; Kim, Sang Hoon; Kim, Jong-Kil; Chai, Young Gyu; Kim, Hee Taik

    2013-02-01

    The shortage of safe drinking water in developing countries and at the sites of natural disaster has spurred scientists to develop more effective materials for water disinfection at the point of use. In the present study, silver nanoparticle supported silica beads (Ag-NPBs) with sizes ranging from 0.5 to 1 mm were prepared, and their potential for water disinfection was examined. Escherichia coli was utilized to assess water disinfection potential by flow tests using a filter column filled with Ag-NPBs. Ag-NPBs inactivated > 99% of E. coli with a contact time of several seconds when the input water had a bacterial load of approximately 106 colony-forming units per mL. Ag-NPBs have an antibacterial capacity of 4.5 L/g. The effect of ammonium and urea on the release rate of silver into filtrate was investigated. The results suggest that Ag-NPBs could be an effective material for water disinfection.

  18. Hollow mesoporous silica nanoparticles for intracellular delivery of fluorescent dye

    PubMed Central

    2011-01-01

    In this study, hollow mesoporous silica nanoparticles (HMSNs) were synthesized using the sol-gel/emulsion approach and its potential application in drug delivery was assessed. The HMSNs were characterized, by transmission electron microscopy (TEM), Scanning Electron Microscopy (SEM), nitrogen adsorption/desorption and Brunauer-Emmett-Teller (BET), to have a mesoporous layer on its surface, with an average pore diameter of about 2 nm and a surface area of 880 m2/g. Fluorescein isothiocyanate (FITC) loaded into these HMSNs was used as a model platform to assess its efficacy as a drug delivery tool. Its release kinetic study revealed a sequential release of FITC from the HMSNs for over a period of one week when soaked in inorganic solution, while a burst release kinetic of the dye was observed just within a few hours of soaking in organic solution. These FITC-loaded HMSNs was also found capable to be internalized by live human cervical cancer cells (HeLa), wherein it was quickly released into the cytoplasm within a short period of time after intracellular uptake. We envision that these HMSNs, with large pores and high efficacy to adsorb chemicals such as the fluorescent dye FITC, could serve as a delivery vehicle for controlled release of chemicals administered into live cells, opening potential to a diverse range of applications including drug storage and release as well as metabolic manipulation of cells. PMID:21208421

  19. Facile synthesis of size controllable dendritic mesoporous silica nanoparticles.

    PubMed

    Yu, Ye-Jun; Xing, Jun-Ling; Pang, Jun-Ling; Jiang, Shu-Hua; Lam, Koon-Fung; Yang, Tai-Qun; Xue, Qing-Song; Zhang, Kun; Wu, Peng

    2014-12-24

    The synthesis of highly uniform mesoporous silica nanospheres (MSNs) with dendritic pore channels, particularly ones with particle sizes below 200 nm, is extremely difficult and remains a grand challenge. By a combined synthetic strategy using imidazolium ionic liquids (ILs) with different alkyl lengths as cosurfactants and Pluronic F127 nonionic surfactants as inhibitors of particle growth, the preparation of dendritic MSNs with controlled diameter between 40 and 300 nm was successfully realized. An investigation of dendritic MSNs using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen physisorption revealed that the synthesis of dendritic MSNs at larger size (100-300 nm) strongly depends on the alkyl lengths of cationic imidazolium ILs; while the average size of dendritic MSNs can be controlled within the range of 40-100 nm by varying the amount of Pluronic F127. The Au@MSNs can be used as a catalyst for the reduction of 4-nitrophenol by NaBH4 into 4-aminophenol and exhibit excellent catalytic performance. The present discovery of the extended synthesis conditions offers reproducible, facile, and large-scale synthesis of the monodisperse spherical MSNs with precise size control and, thus, has vast prospects for future applications of ultrafine mesostructured nanoparticle materials in catalysis and biomedicine. PMID:25454255

  20. Highly Loaded Mesoporous Silica/Nanoparticle Composites and Patterned Mesoporous Silica Films

    NASA Astrophysics Data System (ADS)

    Kothari, Rohit; Hendricks, Nicholas R.; Wang, Xinyu; Watkins, James J.

    2014-03-01

    Novel approaches for the preparation of highly filled mesoporous silica/nanoparticle (MS/NP) composites and for the fabrication of patterned MS films are described. The incorporation of iron platinum NPs within the walls of MS is achieved at high NP loadings by doping amphiphilic poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (Pluronic®) copolymer templates via selective hydrogen bonding between the pre-synthesized NPs and the hydrophilic portion of the block copolymer. The MS is then synthesized by means of phase selective condensation of tetraethylorthosilicate (TEOS) within the NP loaded block copolymer templates dilated with supercritical carbon dioxide (scCO2) followed by calcination. For patterned films, microphase separated block copolymer/small molecule additive blends are patterned using UV-assisted nanoimprint lithography. Infusion and condensation of a TEOS within template films using ScCO2 as a processing medium followed by calcination yields the patterned MS films. Scanning electron microscopy is used characterize pattern fidelity and transmission electron microscopy analysis confirms the presence of the mesopores. Long range order in nanocomposites is confirmed by low angle x-ray diffraction.

  1. SANS study of interaction of silica nanoparticles with BSA protein and their resultant structure

    SciTech Connect

    Yadav, Indresh Aswal, V. K.; Kohlbrecher, J.

    2014-04-24

    Small angle neutron scattering (SANS) has been carried out to study the interaction of anionic silica nanoparticles (88 Å) with globular protein Bovine Serum Albumin (BSA) (M.W. 66.4 kD) in aqueous solution. The measurements have been carried out on fixed concentration (1 wt %) of Ludox silica nanoparticles with varying concentration of BSA (0–5 wt %) at pH7. Results show that silica nanoparticles and BSA coexist as individual entities at low concentration of BSA where electrostatic repulsive interactions between them prevent their aggregation. However, as the concentration of BSA increases (≥ 0.5 wt %), it induces the attractive depletion interaction among nanoparticles leading to finally their aggregation at higher BSA concentration (2 wt %). The aggregates are found to be governed by the diffusion limited aggregation (DLA) morphology of fractal nature having fractal dimension about 2.4.

  2. Silica nanoparticle-based dual imaging colloidal hybrids: cancer cell imaging and biodistribution.

    PubMed

    Lee, Haisung; Sung, Dongkyung; Kim, Jinhoon; Kim, Byung-Tae; Wang, Tuntun; An, Seong Soo A; Seo, Soo-Won; Yi, Dong Kee

    2015-01-01

    In this study, fluorescent dye-conjugated magnetic resonance (MR) imaging agents were investigated in T mode. Gadolinium-conjugated silica nanoparticles were successfully synthesized for both MR imaging and fluorescence diagnostics. Polyamine and polycarboxyl functional groups were modified chemically on the surface of the silica nanoparticles for efficient conjugation of gadolinium ions. The derived gadolinium-conjugated silica nanoparticles were investigated by zeta potential analysis, transmission electron microscopy, inductively coupled plasma mass spectrometry, and energy dispersive x-ray spectroscopy. MR equipment was used to investigate their use as contrast-enhancing agents in T1 mode under a 9.4 T magnetic field. In addition, we tracked the distribution of the gadolinium-conjugated nanoparticles in both lung cancer cells and organs in mice. PMID:26357472

  3. A New Class of Silica Crosslinked Micellar Core-Shell /nanoparticles."

    SciTech Connect

    Huo, Qisheng; Liu, Jun; Wang, Li Q.; Jiang, Yingbing; Lambert, Timothy N.; Fang, Erica

    2006-05-17

    Micellar nanoparticles made of surfactants and polymers have attracted wide attention in the materials and biomedical community for controlled drug delivery, molecular imaging and sensing; however, their long-term stability remains a topic of intense study. Here we report a new class of robust, ultrafine (10nm) silica core-shell nanoparticles formed from silica crosslinked, individual block copolymer micelles. Compared with pure polymer micelles, the new core-shell nanoparticles have significantly improved stability and do not break down during dilution. They also achieve much higher loading capacity for a wide range of chemicals, with the entrapped molecules slowly released over a much longer period of time. A wide range of functional groups can be easily incorporated through co-condensation with the silica matrix. The potential to deliver hydrophobic agents into cancer cells has been demonstrated. Because of their unique properties, these novel core-shell nanoparticles could potentially provide a new nanomedicine platform for imaging, detection and treatment.

  4. Removal of sulphur mustard, sarin and simulants on impregnated silica nanoparticles.

    PubMed

    Saxena, Amit; Srivastava, Avanish K; Singh, Beer; Goyal, Anshu

    2012-04-15

    Silica nanoparticles of diameter, 24-75 nm and surface area, 875 m(2)/g were synthesized using aero-gel route. Thereafter, nanoparticles were impregnated with reactive chemicals, and used as reactive adsorbent to study the removal of toxic nerve and blister chemical warfare agents and their simulants from solutions. Trichloroisocyanuric acid impregnated silica nanoparticles showed the best performance and indicated physisorption followed by chemisorption/degradation of toxicants. This indicated their suitability as universal decontaminant for nerve and blister agents. This system showed a decrease in t(1/2) from 1210 to 2.8 min for the removal of king of chemical warfare agents, i.e., sulphur mustard. Hydrolysis, dehydrohalogenation and oxidation reactions were found to be the route of degradation of toxicants over impregnated silica nanoparticles. PMID:21871717

  5. SANS study of interaction of silica nanoparticles with BSA protein and their resultant structure

    NASA Astrophysics Data System (ADS)

    Yadav, Indresh; Aswal, V. K.; Kohlbrecher, J.

    2014-04-01

    Small angle neutron scattering (SANS) has been carried out to study the interaction of anionic silica nanoparticles (88 Å) with globular protein Bovine Serum Albumin (BSA) (M.W. 66.4 kD) in aqueous solution. The measurements have been carried out on fixed concentration (1 wt %) of Ludox silica nanoparticles with varying concentration of BSA (0-5 wt %) at pH7. Results show that silica nanoparticles and BSA coexist as individual entities at low concentration of BSA where electrostatic repulsive interactions between them prevent their aggregation. However, as the concentration of BSA increases (≥ 0.5 wt %), it induces the attractive depletion interaction among nanoparticles leading to finally their aggregation at higher BSA concentration (2 wt %). The aggregates are found to be governed by the diffusion limited aggregation (DLA) morphology of fractal nature having fractal dimension about 2.4.

  6. Preparation and characterization of poly (ethylene glycol)-coated Stoeber silica nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Kopelman, Raoul; Xu, Hao; Yan, Fei; Monson, Eric E.; Tang, Wei; Schneider, Randy; Philbert, Martin A.

    2002-06-01

    Monodisperse, spherical, polyethylene glycol (PEG)-coated silica nanoparticles have been prepared in the size range of 50-350 nm, and their size distribution were characterized by SEM and multi-angle static light scattering experiments. The chemical binding of PEG to the silica nanoparticles was confirmed by IR spectroscopy. The biocompatibility of these PEGylated nanoparticles was also studied by non-specific protein binding tests and in-vivo toxicology studies in live animals. These silica nanoparticles, as a matrix for encapsulation of certain reagents, have been used for the fabrication of intracellular sensors and have potential for applications to in vivo diagnosis, analysis and measurements, due to their small physical size and their biocompatibility, both stemming from the specialized PEG coating.

  7. Supramolecular Complex Antioxidant Consisting of Vitamins C, E and Hydrophilic-Hydrophobic Silica Nanoparticles

    NASA Astrophysics Data System (ADS)

    Laguta, I. V.; Kuzema, P. O.; Stavinskaya, O. N.; Kazakova, O. A.

    Samples with varied amount of surface trimethylsilyl groups were obtained via gas-phase chemical modification of silica nanoparticles. The biocompatibility tests conducted in erythrocyte suspension have shown that hydrophobization of silica decreases its damaging effect to the cells. Being wettable in aqueous media, partially silylated silicas have higher affinity to hydrophobic bioactive molecules in comparison with the initial silica. Novel antioxidant consisting of vitamins C and E and silica with 40% of surface trimethylsilyl groups was formulated. It was found that supramolecular complexes are formed on the silica surface due to the affinity of water- and fat-soluble antioxidants to hydrophilic silanol and hydrophobic trimethylsilyl groups, respectively. Test reactions (total phenolic index determination, DPPH test) and in vitro studies (spectral analysis of erythrocyte suspensions undergoing UV irradiation) revealed the correlation between antioxidant activity of the complex antioxidant and the vitamins’ content. The antioxidant remained active during long-term storage under standard conditions.

  8. Supramolecular Complex Antioxidant Consisting of Vitamins C, E and Hydrophilic-Hydrophobic Silica Nanoparticles

    NASA Astrophysics Data System (ADS)

    Laguta, I. V.; Kuzema, P. O.; Stavinskaya, O. N.; Kazakova, O. A.

    Samples with varied amount of surface trimethylsilyl groups were obtained via gas-phase chemical modification of silica nanoparticles. The biocompatibility tests conducted in erythrocyte suspension have shown that hydrophobization of silica decreases its damaging effect to the cells. Being wettable in aqueous media, partially silylated silicas have higher affinity to hydrophobic bioactive molecules in comparison with the initial silica. Novel antioxidant consisting of vitamins C and E and silica with 40% of surface trimethylsilyl groups was formulated. It was found that supramolecular complexes are formed on the silica surface due to the affinity of water- and fat-soluble antioxidants to hydrophilic silanol and hydrophobic trimethylsilyl groups, respectively. Test reactions (total phenolic index determination, DPPH test) and in vitro studies (spectral analysis of erythrocyte suspensions undergoing UV irradiation) revealed the correlation between antioxidant activity of the complex antioxidant and the vitamins' content. The antioxidant remained active during long-term storage under standard conditions.

  9. Surface functionalization of silica-coated magnetic nanoparticles for covalent attachment of cholesterol oxidase

    NASA Astrophysics Data System (ADS)

    Šulek, Franja; Drofenik, Miha; Habulin, Maja; Knez, Željko

    2010-01-01

    A systematic approach towards the fabrication of highly functionalized silica shell magnetic nanoparticles, presently used for enzyme immobilization, is herein fully presented. The synthesis of bare maghemite (γ-Fe 2O 3) nanoparticles was accomplished by thermal co-precipitation of iron ions in ammonia alkaline solution at harsh reaction conditions, respectively. Primary surface engineering of maghemite nanoparticles was successfully performed by the proper deposition of silica onto nanoparticles surface under strictly regulated reaction conditions. Next, the secondary surface functionalization of the particles was achieved by coating the particles with organosilane followed by glutaraldehyde activation in order to enhance protein immobilization. Covalent immobilization of cholesterol oxidase was attempted afterwards. The structural and magnetic properties of magnetic silica nanocomposites were characterized by TEM and vibrating sample magnetometer (VSM) instruments. X-ray diffraction measurements confirmed the spinel structure and average size of uncoated maghemite nanoparticles to be around 20 nm in diameter. SEM-EDS spectra indicated a strong signal for Si, implying the coating procedure of silica onto the particles surface to be successfully accomplished. Fourier transform infrared (FT-IR) spectra analysis confirmed the binding of amino silane molecules onto the surface of the maghemite nanoparticles mediated Si-O-Si chemical bonds. Compared to the free enzyme, the covalently bound cholesterol oxidase retained 50% of its activity. Binding of enzyme onto chemically modified magnetic nanoparticles via glutaraldehyde activation is a promising method for developing biosensing components in biomedicine.

  10. In vivo penetration of bare and lipid-coated silica nanoparticles across the human stratum corneum.

    PubMed

    Iannuccelli, Valentina; Bertelli, Davide; Romagnoli, Marcello; Scalia, Santo; Maretti, Eleonora; Sacchetti, Francesca; Leo, Eliana

    2014-10-01

    Skin penetration of silica nanoparticles (NP) currently used in pharmaceutical and cosmetic products is a topic of interest not only to evaluate their possible toxicity, but also to understand their behaviour upon contact with the skin and to exploit their potential positive effects in drug or cosmetic delivery field. Therefore, the present work aimed to elucidate the in vivo mechanism by which amorphous hydrophilic silica NP enter human stratum corneum (SC) through the evaluation of the role played by the nanoparticle surface polarity and the human hair follicle density. Two silica samples, bare hydrophilic silica (B-silica, 162±51nm in size) and hydrophobic lipid-coated silica (LC-silica, 363±74nm in size) were applied on both the volar and dorsal side of volunteer forearms. Twelve repetitive stripped tapes were removed from the human skin and evaluated for elemental composition by Energy Dispersive X-ray (EDX) analysis and for silicon content by Inductively Coupled Plasma quadrupole Mass Spectrometry (ICP-MS). All the stripped tapes revealed nanosized structures generally located in the broad spaces between corneocytes and characterized by the same elemental composition (relative weight percentage of silicon and silicon to oxygen weight ratio) than that of the applied samples. However, only about 10% B-silica permeated until the deepest SC layers considered in the study indicating a silica retention in the upper layers of SC, regardless of the hair follicle density. Otherwise, the exposure to LC-silica led to a greater silica skin penetration extent into the deeper SC layers (about 42% and 18% silica following volar and dorsal forearm application, respectively) indicating that the NP surface polarity played a predominant role on that of their size in determining the route and the extent of penetration. PMID:25139292

  11. Modeling the self-assembly of silica-templated nanoparticles in the initial stages of zeolite formation.

    PubMed

    Chien, Szu-Chia; Auerbach, Scott M; Monson, Peter A

    2015-05-01

    The reaction ensemble Monte Carlo method was used to model the self-assembly and structure of silica nanoparticles found in the initial stages of the clear-solution synthesis of the silicalite-1 zeolite. Such nanoparticles, which comprise both silica and organic structure-directing agents (OSDAs), are believed to play a crucial role in the formation of silica nanoporous materials, yet very limited atomic-level structural information is available for these nanoparticles. We have modeled silica monomers as flexible tetrahedra with spring constants fitted in previous work to silica bulk moduli and OSDAs as spheres attracted to anionic silica monomers. We have studied one-step and two-step formation mechanisms, the latter involving the initial association of silica species and OSDAs driven by physical solution forces, followed by silica condensation/hydrolysis reactions simulated with reaction ensemble Monte Carlo. The two-step process with preassociation was found to be crucial for generating nearly spherical nanoparticles; otherwise, without preassociation they exhibited jagged, ramified structures. The two-step nanoparticles were found to exhibit a core-shell structure with mostly silica in the core surrounded by a diffuse shell of OSDAs, in agreement with SANS and SAXS data. The Qn distribution, quantifying silicon atoms bound to n bridging oxygens, found in the simulated nanoparticles is in broad agreement with (29)Si solid-state NMR data on smaller, 2 nm nanoparticle populations. Ring-size distributions from the simulated nanoparticles show that five-membered rings are prevalent when considering OSDA/silica mole fractions (∼0.2) that lead to silicalite-1, in agreement with a previous IR and modeling study. Nanoparticles simulated with higher OSDA concentrations show ring-size distributions shifted to smaller rings, with three-membered silica rings dominating at an OSDA/silica mole fraction of 0.8. Our simulations show no evidence of long-range silicalite-1

  12. Synthesis of Polystyrene-Silica Composite Particles via One-Step Nanoparticle-Stabilized Emulsion Polymerization

    NASA Astrophysics Data System (ADS)

    Dai, Lenore; Ma, Huan

    2009-03-01

    Polystyrene-silica core-shell composite particles are prepared by one-step emulsion polymerization with a nonionic initiator VA-086, solely stabilized by silica nanoparticles. The silica nanoparticles are successfully incorporated into as the shell, likely due to the fact that the nanoparticles are thermodynamically favorable to self-assemble and remain at the liquid-liquid interfaces during the emulsion polymerization. The silica content, determined by thermogravimetric analysis, is approximately 20 wt% in the composite particles. In addition, we further explore the polymerization mechanism by studying the particle growth as a function of initiator concentration and reaction time: when the silica/monomer ratio is increased from 0.83 wt% to 2.5 wt%, the particle size at 24 hour reaction time decreases for a fixed monomer amount, probably due to a larger number of nuclei at the initial stage of polymerization. Further increasing the initiator/monomer ratio to 4.2 wt% does not continually decrease the particle size, which may be limited by the stabilization provided by a fixed concentration of silica nanoparticles. The surface coverage also changes with initiator concentration and reaction time although the underlying mechanism is not fully understood.

  13. Effect of silica nanoparticles on reinforcement of poly(phenylene ether) based thermoplastic elastomer.

    PubMed

    Gupta, Samik; Maiti, Parnasree; Krishnamoorthy, Kumar; Krishnamurthy, Raja; Menon, Ashok; Bhowmick, Anil K

    2008-04-01

    Reinforcement of a novel poly(phenylene ether) (PPE) based thermoplastic elastomer (TPE), i.e., styrene-ethylene-butylene-styrene (SEBS)/ethylene vinyl acetate (EVA) and PPE-polystyrene (PS), was studied to develop a reinforced thermoplastic elastomer or thermoplastic vulcanizate (TPV). An effort was made to reinforce selectively the elastomeric dispersed phase of EVA by silica nanoparticles and silica sol-gel precursors, like alkoxy orthosilanes, using twin-screw extrusion and injection molding processes. Improvement of tensile strength and percent elongation at break was observed both with silica nanoparticles and tetraethoxy orthosilane (TEOS). Addition of TEOS transformed the dispersed EVA lamellar morphology into semispherical domains as a consequence of possible crosslinking. Soxhlet extraction was done on the silica and TEOS reinforced materials. The insoluble residues collected from both the silica and TEOS reinforced samples were analyzed in detail using both morphological and spectroscopic studies. This extensive study also provided an in-depth conceptual understanding of the PPE based TPE behavior upon reinforcement with silica nanoparticles and silica sol-gel precursors and the effect of reinforcement on recycling behavior. PMID:18572622

  14. Effect of silica nanoparticles on polyurethane foaming process and foam properties

    NASA Astrophysics Data System (ADS)

    Francés, A. B.; Navarro Bañón, M. V.

    2014-08-01

    Flexible polyurethane foams (FPUF) are commonly used as cushioning material in upholstered products made on several industrial sectors: furniture, automotive seating, bedding, etc. Polyurethane is a high molecular weight polymer based on the reaction between a hydroxyl group (polyol) and isocyanate. The density, flowability, compressive, tensile or shearing strength, the thermal and dimensional stability, combustibility, and other properties can be adjusted by the addition of several additives. Nanomaterials offer a wide range of possibilities to obtain nanocomposites with specific properties. The combination of FPUF with silica nanoparticles could develop nanocomposite materials with unique properties: improved mechanical and thermal properties, gas permeability, and fire retardancy. However, as silica particles are at least partially surface-terminated with Si-OH groups, it was suspected that the silica could interfere in the reaction of poyurethane formation.The objective of this study was to investigate the enhancement of thermal and mechanical properties of FPUF by the incorporation of different types of silica and determining the influence thereof during the foaming process. Flexible polyurethane foams with different loading mass fraction of silica nanoparticles (0-1% wt) and different types of silica (non treated and modified silica) were synthesized. PU/SiO2 nanocomposites were characterized by FTIR spectroscopy, TGA, and measurements of apparent density, resilience and determination of compression set. Addition of silica nanoparticles influences negatively in the density and compression set of the foams. However, resilience and thermal stability of the foams are improved. Silica nanoparticles do not affect to the chemical structure of the foams although they interfere in the blowing reaction.

  15. Bioconjugated fluorescent silica nanoparticles for the rapid detection of Entamoeba histolytica.

    PubMed

    Hemadi, Ahmad; Ekrami, Alireza; Oormazdi, Hormozd; Meamar, Ahmad Reza; Akhlaghi, Lame; Samarbaf-Zadeh, Ali Reza; Razmjou, Elham

    2015-05-01

    Rapid detection of Entamoeba histolytica based on fluorescent silica nanoparticle (FSNP) indirect immunofluorescence microscopy was evaluated. Silica nanoparticles were synthesized using Stöber's method, with their surface activated to covalently bind to, and immobilize, protein A. For biolabeling, FSNP was added to conjugated E. histolytica trophozoites with monoclonal anti-E. histolytica IgG1 for microscopic observation of fluorescence. Fluorescent silica nanoparticle sensitivity was determined with axenically cultured E. histolytica serially diluted to seven concentrations. Specificity was evaluated using other intestinal protozoa. Fluorescent silica nanoparticles detected E. histolytica at the lowest tested concentration with no cross-reaction with Entamoeba dispar, Entamoeba moshkovskii, Blastocystis sp., or Giardia lamblia. Visualization of E. histolytica trophozoites with anti-E. histolytica antibody labeled with fluorescein isothiocyanate (FITC) was compared with that using anti-E. histolytica antibody bioconjugated FSNP. Although FITC and FSNP produced similar results, the amount of specific antibody required for FITC to induce fluorescence of similar intensity was fivefold that for FSNP. Fluorescent silica nanoparticles delivered a rapid, simple, cost-effective, and highly sensitive and specific method of detecting E. histolytica. Further study is needed before introducing FSNP for laboratory diagnosis of amoebiasis. PMID:25697865

  16. Preparation, characterization, and in vivo evaluation of tanshinone IIA solid dispersions with silica nanoparticles

    PubMed Central

    Jiang, Yan-rong; Zhang, Zhen-hai; Liu, Qi-yuan; Hu, Shao-ying; Chen, Xiao-yun; Jia, Xiao-bin

    2013-01-01

    We prepared solid dispersions (SDs) of tanshinone IIA (TSIIA) with silica nanoparticles, which function as dispersing carriers, using a spray-drying method and evaluated their in vitro dissolution and in vivo performance. The extent of TSIIA dissolution in the silica nanoparticles/TSIIA system (weight ratio, 5:1) was approximately 92% higher than that of the pure drug after 60 minutes. However, increasing the content of silica nanoparticles from 5:1 to 7:1 in this system did not significantly increase the rate or extent of TSIIA dissolution. The physicochemical properties of SDs were investigated using scanning electron microscopy, differential scanning calorimetry, X-ray powder diffraction, and Fourier transforms infrared spectroscopy. Studying the stability of the SDs of TSIIA revealed that the drug content of the formulation and dissolution behavior was unchanged under the applied storage conditions. In vivo tests showed that SDs of the silica nanoparticles/TSIIA had a significantly larger area under the concentration-time curve, which was 1.27 times more than that of TSIIA (P < 0.01). Additionally, the values of maximum plasma concentration and the time to reach maximum plasma concentration of the SDs were higher than those of TSIIA and the physical mixing system. Based on these results, we conclude that the silica nanoparticle based SDs achieved complete dissolution, increased absorption rate, maintained drug stability, and showed improved oral bioavailability compared to TSIIA alone. PMID:23836971

  17. Uptake of bright fluorophore core-silica shell nanoparticles by biological systems

    PubMed Central

    Zane, Andrew; McCracken, Christie; Knight, Deborah A; Young, Tanya; Lutton, Anthony D; Olesik, John W; Waldman, W James; Dutta, Prabir K

    2015-01-01

    Nanoparticles are used in a variety of consumer applications. Silica nanoparticles in particular are common, including as a component of foods. There are concerns that ingested nano-silica particles can cross the intestinal epithelium, enter the circulation, and accumulate in tissues and organs. Thus, tracking these particles is of interest, and fluorescence spectroscopic methods are well-suited for this purpose. However, nanosilica is not fluorescent. In this article, we focus on core-silica shell nanoparticles, using fluorescent Rhodamine 6G, Rhodamine 800, or CdSe/CdS/ZnS quantum dots as the core. These stable fluorophore/silica nanoparticles had surface characteristics similar to those of commercial silica particles. Thus, they were used as model particles to examine internalization by cultured cells, including an epithelial cell line relevant to the gastrointestinal tract. Finally, these particles were administered to mice by gavage, and their presence in various organs, including stomach, small intestine, cecum, colon, kidney, lung, brain, and spleen, was examined. By combining confocal fluorescence microscopy with inductively coupled plasma mass spectrometry, the presence of nanoparticles, rather than their dissolved form, was established in liver tissues. PMID:25759579

  18. Highly efficient antibody immobilization with multimeric protein Gs coupled magnetic silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Choi, H. K.; Chang, J. H.

    2011-10-01

    This work reports the immobilization of monomeric, dimeric and trimer protein Gs onto silica magnetic nanoparticles for self-oriented antibody immobilization. To achieve this, we initially prepared the silica-coated magnetic nanoparticle having about 170 nm diameters. The surface of the silica coated magnetic nanoparticles was modified with 3- aminopropyl-trimethoxysilane (APTMS) to chemically link to multimeric protein Gs. The conjugation of amino groups on the SiO2-MNPs to cysteine tagged in multimeric protein Gs was performed using a sulfo-SMCC coupling procedure. The binding efficiencies of monomer, dimer and trimer were 77 %, 67 % and 55 % respectively. However, the efficiencies of antibody immobilization were 70 %, 83 % and 95 % for monomeric, dimeric and trimeric protein G, respectively. To prove the enhancement of accessibility by using multimeric protein G, FITC labeled goat-anti-mouse IgG was treated to mouse IgG immobilized magnetic silica nanoparticles through multimeric protein G. FITC labeled goat anti-mouse IgGs were more easily bound to mouse IgG immobilized by trimeric protein G than others. Finally protein G bound silica magnetic nanoparticles were utilized to develop highly sensitive immunoassay to detect hepatitis B antigen.

  19. Substrate responsive colloidal system based on luminescent Tb(III) doped silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Mustafina, Asiya R.; Bochkova, Olga D.; Fedorenko, Svetlana V.; Skripacheva, Viktoriya V.; Zakharova, Lucia Ya.; Kadirov, Marcil K.; Nizameyev, Irek R.; Konovalov, Alexander I.; Soloveva, Svetlana E.

    2010-09-01

    Positively charged luminescent silica nanoparticles loaded with Tb(III) complex were prepaired by reverse microemulsion procedure with further modification by gemini surfactant. The ξ-potential values and dynamic light scattering data indicate high positive charge and colloidal stability of the as prepaired nanoparticles. The high affinity of these nanoparticles to anions is verified by spectrophotometric measurements with dye molecules, namely phenol red. The insertion of phenol red anions into surfactant bilayer at silica/water interface results in the quenching effect on Tb(III)-centered luminescence of the nanoparticles. Thus "on-off" switching of Tb-centered luminescence indicates the formation of the positively charged bilayer at the silica/water interface. The binding of dodecylsulfate anions with cationic adlayer at the silica/water interface results in the recharging of silica nanoparticles. This recharging can be manifested through the "off-on" luminescent switching, resulted from the displacement of dye anions and reestablishment of Tb(III)-centered luminescence.

  20. Substrate responsive colloidal system based on luminescent Tb(III) doped silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Mustafina, Asiya R.; Bochkova, Olga D.; Fedorenko, Svetlana V.; Skripacheva, Viktoriya V.; Zakharova, Lucia Ya.; Kadirov, Marcil K.; Nizameyev, Irek R.; Konovalov, Alexander I.; Soloveva, Svetlana E.

    2011-02-01

    Positively charged luminescent silica nanoparticles loaded with Tb(III) complex were prepaired by reverse microemulsion procedure with further modification by gemini surfactant. The ξ-potential values and dynamic light scattering data indicate high positive charge and colloidal stability of the as prepaired nanoparticles. The high affinity of these nanoparticles to anions is verified by spectrophotometric measurements with dye molecules, namely phenol red. The insertion of phenol red anions into surfactant bilayer at silica/water interface results in the quenching effect on Tb(III)-centered luminescence of the nanoparticles. Thus "on-off" switching of Tb-centered luminescence indicates the formation of the positively charged bilayer at the silica/water interface. The binding of dodecylsulfate anions with cationic adlayer at the silica/water interface results in the recharging of silica nanoparticles. This recharging can be manifested through the "off-on" luminescent switching, resulted from the displacement of dye anions and reestablishment of Tb(III)-centered luminescence.

  1. Inducing cell cycle arrest and apoptosis by dimercaptosuccinic acid modified Fe3O4 magnetic nanoparticles combined with nontoxic concentration of bortezomib and gambogic acid in RPMI-8226 cells

    PubMed Central

    Zhang, Wei; Qiao, Lixing; Wang, Xinchao; Senthilkumar, Ravichandran; Wang, Fei; Chen, Baoan

    2015-01-01

    The purpose of this study was to determine the potential benefits of combination therapy using dimercaptosuccinic acid modified iron oxide (DMSA-Fe3O4) magnetic nanoparticles (MNPs) combined with nontoxic concentration of bortezomib (BTZ) and gambogic acid (GA) on multiple myeloma (MM) RPMI-8226 cells and possible underlying mechanisms. The effects of BTZ-GA-loaded MNP-Fe3O4 (BTZ-GA/MNPs) on cell proliferation were assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,4,-diphenyltetrazolium bromide (MTT) method. Cell cycle and apoptosis were detected using the terminal deoxyribonucleotidyl transferase (TdT)-mediated biotin-16-dUTP nick-end labeling (TUNEL) assay and flow cytometry (FCM). Furthermore, DMSA-Fe3O4 MNPs were characterized in terms of distribution, apoptotic morphology, and cellular uptake by transmission electron microscopy (TEM) and 4,6-diamidino-2-phenylindole (DAPI) staining. Subsequently, the effect of BTZ-GA/MNPs combination on PI3K/Akt activation and apoptotic-related protein were appraised by Western blotting. MTT assay and hematoxylin and eosin (HE) staining were applied to elevate the functions of BTZ-GA/MNPs combination on the tumor xenograft model and tumor necrosis. The results of this study revealed that the majority of MNPs were quasi-spherical and the MNPs taken up by cells were located in the endosome vesicles of cytoplasm. Nontoxic concentration of BTZ-GA/MNPs increased G2/M phase cell cycle arrest and induced apoptosis in RPMI-8226 cells. Furthermore, the combination of BTZ-GA/MNPs activated phosphorylated Akt levels, Caspase-3, and Bax expression, and down-regulated the PI3K and Bcl-2 levels significantly. Meanwhile, the in vivo tumor xenograft model indicated that the treatment of BTZ-GA/MNPs decreased the tumor growth and volume and induced cell apoptosis and necrosis. These findings suggest that chemotherapeutic agents polymerized MNPs-Fe3O4 with GA could serve as a better alternative for targeted therapeutic approaches to treat multiple

  2. Molecular dynamics simulations of silica nanoparticles grafted with poly(ethylene oxide) oligomer chains.

    PubMed

    Hong, Bingbing; Panagiotopoulos, Athanassios Z

    2012-03-01

    A molecular model of silica nanoparticles grafted with poly(ethylene oxide) oligomers has been developed for predicting the transport properties of nanoparticle organic-hybrid materials (NOHMs). Ungrafted silica nanoparticles in a medium of poly(ethylene oxide) oligomers were also simulated to clarify the effect of grafting on the dynamics of nanoparticles and chains. The model approximates nanoparticles as solid spheres and uses a united-atom representation for chains, including torsional and bond-bending interactions. The calculated viscosities from Green-Kubo relationships and temperature extrapolation are of the same order of magnitude as experimental data but show a smaller activation energy relative to real NOHMs systems. Grafted systems have higher viscosities, smaller diffusion coefficients, and slower chain dynamics than the ungrafted ones at high temperatures. At lower temperatures, grafted systems exhibit faster dynamics for both nanoparticles and chains relative to ungrafted systems, because of lower aggregation of particles and enhanced correlations between nanoparticles and chains. This agrees with the experimental observation that NOHMs have liquidlike behavior in the absence of a solvent. For both grafted and ungrafted systems at low temperatures, increasing chain length reduces the volume fraction of nanoparticles and accelerates the dynamics. However, at high temperatures, longer chains slow down nanoparticle diffusion. From the Stokes-Einstein relationship, it was determined that the coarse-grained treatment of nanoparticles leads to slip on the nanoparticle surfaces. Grafted systems obey the Stokes-Einstein relationship over the temperature range simulated, but ungrafted systems display deviations from it. PMID:22243140

  3. Exposure to silica nanoparticles causes reversible damage of the spermatogenic process in mice.

    PubMed

    Xu, Ying; Wang, Na; Yu, Yang; Li, Yang; Li, Yan-Bo; Yu, Yong-Bo; Zhou, Xian-Qing; Sun, Zhi-Wei

    2014-01-01

    Environmental exposure to nanomaterials is inevitable, as nanomaterials have become part of our daily life now. In this study, we firstly investigated the effects of silica nanoparticles on the spermatogenic process according to their time course in male mice. 48 male mice were randomly divided into control group and silica nanoparticle group with 24 mice per group, with three evaluation time points (15, 35 and 60 days after the first dose) per group. Mice were exposed to the vehicle control and silica nanoparticles at a dosage of 20 mg/kg every 3 days, five times over a 13-day period, and were sacrificed at 15, 35 and 60 days after the first dose. The results showed that silica nanoparticles caused damage to the mitochondrial cristae and decreased the levels of ATP, resulting in oxidative stress in the testis by days 15 and 35; however, the damage was repaired by day 60. DNA damage and the decreases in the quantity and quality of epididymal sperm were found by days 15 and 35; but these changes were recovered by day 60. In contrast, the acrosome integrity and fertility in epididymal sperm, the numbers of spermatogonia and sperm in the testes, and the levels of three major sex hormones were not significantly affected throughout the 60-day period. The results suggest that nanoparticles can cause reversible damage to the sperms in the epididymis without affecting fertility, they are more sensitive than both spermatogonia and spermatocytes to silica nanoparticle toxicity. Considering the spermatogenesis time course, silica nanoparticles primarily influence the maturation process of sperm in the epididymis by causing oxidative stress and damage to the mitochondrial structure, resulting in energy metabolism dysfunction. PMID:25003337

  4. Silica Supported Ceria Nanoparticles: A Hybrid Nanostructure To Increase Stability And Surface Reactivity Of Nano-crystalline Ceria

    SciTech Connect

    Munusamy, Prabhakaran; Sanghavi, Shail P.; Varga, Tamas; Thevuthasan, Suntharampillai

    2014-01-21

    The mixed oxidation state (3+/4+) of ceria nanoparticles of smaller sizes make them attractive materials for their catalytic antioxidant biological properties. However the unmodified smaller ceria nanoparticles are limited in their use due to particles agglomeration and reduced surface chemical reactivity in the solutions used to disperse the nanoparticles. This work describes an effort to stabilize small ceria nanoparticles, retaining their desired activity, on a larger stable silica support. The ceria nanoparticles attached to silica was synthesized by a solution synthesis technique in which the surface functional groups of silica nanoparticles were found to be essential for the formation of smaller ceria nanoparticles. The surface chemical and vibrational spectroscopy analysis revealed cerium–silicate (Ce-O-Si) covalent bond linkage between silica and cerium oxide nanoparticles. The colloidal properties (agglomerate particle size and suspension stability) of ceria attached to silica was significantly improved due to inherent physico-chemical characteristics of silica against random collision and gravitation settling as opposed to unmodified ceria nanoparticles in solution. The bio-catalytic activity of ceria nanoparticles in the 3+ oxidation state was not found to be limited by attachment to the silica support as measured by free radical scavenging activity in different biological media conditions.

  5. Modifications in interaction and structure of silica nanoparticle-BSA protein system in aqueous electrolyte solution

    NASA Astrophysics Data System (ADS)

    Yadav, Indresh; Aswal, V. K.; Kohlbrecher, J.

    2015-06-01

    SANS measurements have been carried out to examine the modifications in interaction and structure of anionic silica nanoparticle with anionic BSA protein in presence of an electrolyte. The phase behaviour of anionic silica nanoparticle and anionic BSA protein is governed by the protein induced depletion interaction between nanoparticles. Both nanoparticle and protein coexist individually at low protein concentrations as electrostatic repulsion dominates over the depletion interaction. However, depletion induced fractal aggregates of nanoparticles are formed at higher protein concentrations. These aggregates can be formed at much smaller protein concentration in presence of an electrolyte. We show that both the electrostatic (decrease) and depletion interaction (increase) are modified with an electrolyte. The range of the depletion interaction is found to be significantly larger than the electrostatic interaction.

  6. Anisotropic magnetic porous assemblies of oxide nanoparticles interconnected via silica bridges for catalytic application.

    PubMed

    Wacker, Josias B; Parashar, Virendra K; Gijs, Martin A M

    2011-04-19

    We report the microfluidic chip-based assembly of colloidal silanol-functionalized silica nanoparticles using monodisperse water-in-oil droplets as templates. The nanoparticles are linked via silica bridges, thereby forming superstructures that range from doublets to porous spherical or rod-like micro-objects. Adding magnetite nanoparticles to the colloid generates micro-objects that can be magnetically manipulated. We functionalized such magnetic porous assemblies with horseradish peroxidase and demonstrate the catalytic binding of fluorescent dye-labeled tyramide over the complete effective surface of the superstructure. Such nanoparticle assemblies permit easy manipulation and recovery after a heterogeneous catalytic process while providing a large surface similar to that of the individual nanoparticles. PMID:21417232

  7. Rose Bengal-decorated silica nanoparticles as photosensitizers for inactivation of gram-positive bacteria

    NASA Astrophysics Data System (ADS)

    Guo, Yanyan; Rogelj, Snezna; Zhang, Peng

    2010-02-01

    A new type of photosensitizer, made from Rose Bengal (RB)-decorated silica (SiO2-NH2-RB) nanoparticles, was developed to inactivate gram-positive bacteria, including Methicillin-resistant Staphylococcus aureus (MRSA), with high efficiency through photodynamic action. The nanoparticles were characterized microscopically and spectroscopically to confirm their structures. The characterization of singlet oxygen generated by RB, both free and immobilized on a nanoparticle surface, was performed in the presence of anthracene-9,10-dipropionic acid. The capability of SiO2-NH2-RB nanoparticles to inactivate bacteria was tested in vitro on both gram-positive and gram-negative bacteria. The results showed that RB-decorated silica nanoparticles can inactivate MRSA and Staphylococcus epidermidis (both gram-positive) very effectively (up to eight-orders-of-magnitude reduction). Photosensitizers of such design should have good potential as antibacterial agents through a photodynamic mechanism.

  8. The effect of silica nanoparticles on the mechanical properties of fiber-reinforced composite resins.

    PubMed

    Rezvani, Mohammad Bagher; Atai, Mohammad; Hamze, Faeze; Hajrezai, Reihane

    2016-01-01

    Background. Nanotechnology has introduced many nanoparticles in recent years, which can be incorporated for mechanical improvement of dental materials. However, the existing data are widely sparse. This study investigated the reinforcing effect of silica nanoparticles when incorporated into the matrix phase of an experimental dental fiber-reinforced compositeresin (FRC) through evaluation of its flexural properties. Methods. In this experimental study FRC samples were divided into two main groups (containing two or three bundles),either of whic consisted of five subgroups with 0, 0.2, 0.5, 2 and 5 wt% of silica nanoparticles in the matrix resin (n=10 in each subgroup); a commercial FRC (Angelus, Brazil) was used as the control group (n=10). Three-point bending test was performed to evaluate the flexural strength and modulus. Thereafter, the microstructure of the fractured samples was evalu-ated using scanning electron microscopy (SEM). The results were analyzed with one-way ANOVA and HSD Tukey tests (α = 0.05). Results. The results revealed that the silica nanoparticles had a significant and positive effect on the flexural strength and modulus of FRCs (P<0.05), with no significant differences from 0.2 to 5 wt% of nanoparticles (P > 0.05) in either group with two or three bundles of fibers. Conclusion. Incorporating silica nanoparticles into the FRC resin phase resulted in improved flexural strength and modulus of the final product. PMID:27429728

  9. The effect of silica nanoparticles on the mechanical properties of fiber-reinforced composite resins

    PubMed Central

    Rezvani, Mohammad Bagher; Atai, Mohammad; Hamze, Faeze; Hajrezai, Reihane

    2016-01-01

    Background. Nanotechnology has introduced many nanoparticles in recent years, which can be incorporated for mechanical improvement of dental materials. However, the existing data are widely sparse. This study investigated the reinforcing effect of silica nanoparticles when incorporated into the matrix phase of an experimental dental fiber-reinforced compositeresin (FRC) through evaluation of its flexural properties. Methods. In this experimental study FRC samples were divided into two main groups (containing two or three bundles),either of whic consisted of five subgroups with 0, 0.2, 0.5, 2 and 5 wt% of silica nanoparticles in the matrix resin (n=10 in each subgroup); a commercial FRC (Angelus, Brazil) was used as the control group (n=10). Three-point bending test was performed to evaluate the flexural strength and modulus. Thereafter, the microstructure of the fractured samples was evalu-ated using scanning electron microscopy (SEM). The results were analyzed with one-way ANOVA and HSD Tukey tests (α = 0.05). Results. The results revealed that the silica nanoparticles had a significant and positive effect on the flexural strength and modulus of FRCs (P<0.05), with no significant differences from 0.2 to 5 wt% of nanoparticles (P > 0.05) in either group with two or three bundles of fibers. Conclusion. Incorporating silica nanoparticles into the FRC resin phase resulted in improved flexural strength and modulus of the final product. PMID:27429728

  10. Lung toxicities of core–shell nanoparticles composed of carbon, cobalt, and silica

    PubMed Central

    Al Samri, Mohammed T; Silva, Rafael; Almarzooqi, Saeeda; Albawardi, Alia; Othman, Aws Rashad Diab; Al Hanjeri, Ruqayya SMS; Al Dawaar, Shaikha KM; Tariq, Saeed; Souid, Abdul-Kader; Asefa, Tewodros

    2013-01-01

    We present here comparative assessments of murine lung toxicity (biocompatibility) after in vitro and in vivo exposures to carbon (C–SiO2-etched), carbon–silica (C–SiO2), carbon–cobalt–silica (C–Co–SiO2), and carbon–cobalt oxide–silica (C–Co3O4–SiO2) nanoparticles. These nanoparticles have potential applications in clinical medicine and bioimaging, and thus their possible adverse events require thorough investigation. The primary aim of this work was to explore whether the nanoparticles are biocompatible with pneumatocyte bioenergetics (cellular respiration and adenosine triphosphate content). Other objectives included assessments of caspase activity, lung structure, and cellular organelles. Pneumatocyte bioenergetics of murine lung remained preserved after treatment with C–SiO2-etched or C–SiO2 nanoparticles. C–SiO2-etched nanoparticles, however, increased caspase activity and altered lung structure more than C–SiO2 did. Consistent with the known mitochondrial toxicity of cobalt, both C–Co–SiO2 and C–Co3O4–SiO2 impaired lung tissue bioenergetics. C–Co–SiO2, however, increased caspase activity and altered lung structure more than C–Co3O4–SiO2. The results indicate that silica shell is essential for biocompatibility. Furthermore, cobalt oxide is the preferred phase over the zerovalent Co(0) phase to impart biocompatibility to cobalt-based nanoparticles. PMID:23658487

  11. Targeted anticancer prodrug with mesoporous silica nanoparticles as vehicles

    NASA Astrophysics Data System (ADS)

    Fan, Jianquan; Fang, Gang; Wang, Xiaodan; Zeng, Fang; Xiang, Yufei; Wu, Shuizhu

    2011-11-01

    A targeted anticancer prodrug system was fabricated with 180 nm mesoporous silica nanoparticles (MSNs) as carriers. The anticancer drug doxorubicin (DOX) was conjugated to the particles through an acid-sensitive carboxylic hydrazone linker which is cleavable under acidic conditions. Moreover, folic acid (FA) was covalently conjugated to the particle surface as the targeting ligand for folate receptors (FRs) overexpressed in some cancer cells. The in vitro release profiles of DOX from the MSN-based prodrug systems showed a strong dependence on the environmental pH values. The fluorescent dye FITC was incorporated in the MSNs so as to trace the cellular uptake on a fluorescence microscope. Cellular uptakes by HeLa, A549 and L929 cell lines were tested for FA-conjugated MSNs and plain MSNs respectively, and a much more efficient uptake by FR-positive cancer cells (HeLa) can be achieved by conjugation of folic acid onto the particles because of the folate-receptor-mediated endocytosis. The cytotoxicities for the FA-conjugated MSN prodrug, the plain MSN prodrug and free DOX against three cell lines were determined, and the result indicates that the FA-conjugated MSN prodrug exhibits higher cytotoxicity to FR-positive cells, and reduced cytotoxicity to FR-negative cells. Thus, with 180 nm MSNs as the carriers for the prodrug system, good drug loading, selective targeting and sustained release of drug molecules within targeted cancer cells can be realized. This study may provide useful insights for designing and improving the applicability of MSNs in targeted anticancer prodrug systems.

  12. Composites of Eu(3+)-doped calcium apatite nanoparticles and silica particles: comparative study of two preparation methods.

    PubMed

    Isobe, Ayumu; Takeshita, Satoru; Isobe, Tetsuhiko

    2015-02-10

    We synthesized composites of Eu(3+)-doped calcium apatite (CaAp:Eu(3+)) nanoparticles and silica particles via two methods: (i) in situ synthesis of CaAp:Eu(3+) in the presence of silica particles and (ii) electrostatic adsorption of CaAp:Eu(3+) nanoparticles on silica particle surfaces. In both methods, submicrometer spherical silica particles were covered with CaAp:Eu(3+) nanoparticles without forming any impurity phases, as confirmed by X-ray diffractometry, Fourier-transform infrared spectroscopy, and scanning electron microscopy. In method i, part of the silica surface acted as a nucleation site for apatite crystals and silica particles were inhomogeneously covered with CaAp:Eu(3+) nanoparticles. In method ii, positively charged CaAp:Eu(3+) nanoparticles were homogeneously adsorbed on the negatively charged silica surface through electrostatic interactions. The bonds between the silica surface and CaAp:Eu(3+) nanoparticles are strong enough not to break under ultrasonic irradiation, irrespective of the synthetic method used. The composite particles showed red photoluminescence corresponding to 4f → 4f transitions of Eu(3+) under near-UV irradiation. Although the absorption coefficient of the forbidden 4f → 4f transitions of Eu(3+) was small, the red emission was detectable with a commercial fluorescence microscope because the CaAp:Eu(3+) nanoparticles accumulated on the silica particle surfaces. PMID:25616077

  13. Capillary electrochromatography using monoamine- and triamine-bonded silica nanoparticles as pseudostationary phases.

    PubMed

    Takeda, Yuto; Hayashi, Yuka; Utamura, Naonori; Takamoto, Chise; Kinoshita, Mitsuhiro; Yamamoto, Sachio; Hayakawa, Takao; Suzuki, Shigeo

    2016-01-01

    Monoamine- and triamine-bonded silica nanoparticles were prepared using 3-aminopropyltrimethoxysilane and N(1)-(3-trimethoxysilylpropyl)diethylenetriamine, respectively, and used as pseudostationary phases for capillary electrochromatography. The amine-bonded silica nanoparticles were tightly adsorbed on the inner wall of a capillary and generated fast electro-osmotic flow (2.59 × 10(-4) cm(2) V(-1) s(-1)) toward the anode in an electric field. The electro-osmotic velocities obtained with 20 nm triamine-bonded silica were three to five times larger than those generated by a fused silica capillary and two times faster than those for the commercial cationic polymer-modified capillary. Fast electro-osmotic flow enables rapid analysis. This method was applied to hydrophilic interaction chromatography (HILIC) mode separation of various samples including the size separation of glucose oligomer derivatives and the resolution of four nucleic acid bases. PMID:26700155

  14. Rapid synthesis of ordered hexagonal mesoporous silica and their incorporation with Ag nanoparticles by solution plasma

    SciTech Connect

    Pootawang, Panuphong; Saito, Nagahiro; Takai, Osamu; Lee, Sang Yul

    2012-10-15

    Graphical abstract: Overall reactions of mesoporous silica and AgNPs-incorporated mesoporous silica syntheses by solution plasma process (SPP). Highlights: ► SPP for rapid synthesis of mesoporous silica. ► SPP for rapid synthesis of mesoporous silica and AgNPs incorporation. ► Higher surface area and larger pore diameter of mesoporous silica synthesized by SPP. -- Abstract: Rapid synthesis of silica with ordered hexagonal mesopore arrangement was obtained using solution plasma process (SPP) by discharging the mixture of P123 triblock copolymer/TEOS in acid solution. SPP, moreover, was utilized for Ag nanoparticles (AgNPs) incorporation in silica framework as one-batch process using silver nitrate (AgNO{sub 3}) solution as precursor. The turbid silicate gel was clearly observed after discharge for 1 min and the white precipitate formed at 3 min. The mesopore with hexagonal arrangement and AgNPs were observed in mesoporous silica. Two regions of X-ray diffraction patterns (2θ < 2° and 2θ = 35–90°) corresponded to the mesoporous silica and Ag nanocrystal characteristics. Comparing with mesoporous silica prepared by a conventional sol–gel route, surface area and pore diameter of mesoporous silica prepared by solution plasma were observed to be larger. In addition, the increase in Ag loading resulted in the decrease in surface area with insignificant variation in the pore diameter of mesoporous silica. SPP could be successfully utilized not only to enhance gelation time but also to increase surface area and pore diameter of mesoporous silica.

  15. Rapid silica atomic layer deposition on large quantities of cohesive nanoparticles.

    PubMed

    Liang, Xinhua; Barrett, Kathryn S; Jiang, Ying-Bing; Weimer, Alan W

    2010-08-01

    Conformal silica films were deposited on anatase titania nanoparticles using rapid silica atomic layer deposition (ALD) in a fluidized bed reactor. Alternating doses of tris(tert-pentoxy)silanol (TPS) and trimethylaluminum (TMA) precursor vapors were used at 175 degrees C. In situ mass spectroscopy verified the growth mechanism through a siloxane polymerization process. Transmission electron microscopy revealed highly conformal and uniform silica nanofilms on the surface of titania nanoparticles. A growth rate of approximately 1.8 nm/cycle was achieved for an underdosed and incomplete polymerization reaction. Primary nanoparticles were coated despite their strong tendency to form dynamic agglomerates during fluidization. Methylene blue oxidation tests indicated that the photoactivity of anatase titania particles was mitigated with the ALD films. PMID:20735095

  16. Effect of particle size on the thermoluminescence (TL) response of silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Siti Shafiqah, A. S.; Amin, Y. M.; Nor, R. Md.; Bradley, D. A.

    2015-12-01

    By means of the sol-gel technique, silica nanoparticles have been synthesized at room temperature using tetraethyl orthosilicate, ethanol, deionized water, and ammonia solution. By increasing the amount of ethanol in the mixture, fine spherically shaped silica nanoparticles have been obtained. Using finite element scanning electron microscopy and energy dispersive x-ray spectroscopy, characterization was made of the morphology and elemental composition of the nanoparticles. The mean particle sizes of three of the samples were measured to be of the order of 80, 140, 550 nm, while the remaining sample contained particles of diameter <10 nm. To provide for thermoluminescence measurements, the samples were irradiated with γ-rays, delivering doses from 1-200 Gy. The smaller size silica particles, of around 80 nm, were observed to produce the largest thermoluminescence yield as a result of the surface to volume ratio increase, providing more accessible thermoluminescence carriers.

  17. Reactions of methyl radicals with silica supported silver nanoparticles in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Zidki, Tomer; Hänel, Andreas; Bar-Ziv, Ronen

    2016-07-01

    Silica supported silver nanoparticles (Ag°-SiO2-NCs, NCs=nanocomposites) suspended in aqueous solutions are efficient catalysts for the dimerization of methyl radicals to produce ethane, while bare silica is quite inert towards the interaction with methyl radicals. In the presence of small amounts of ethanol adsorbed on the SiO2 surface, the reaction path with methyl radicals is changed and methane is formed as the major product.

  18. Phthalocyanine-Gold Nanoparticle Hybrids: Modulating Quenching with a Silica Matrix Shell.

    PubMed

    Baldovi, Herme G; Blas-Ferrando, Vicente M; Ortiz, Javier; Garcia, Hermenegildo; Fernández-Lázaro, Fernando; Sastre-Santos, Ángela

    2016-06-01

    An asymmetrically substituted zinc phthalocyanine (ZnPc) with a terminal dithiolane group is anchored to Au nanoparticles (NPs) directly or through an interposed silica matrix. Transient absorption spectroscopy shows that the quenching of the ZnPc excited state by AuNPs occurs through a photoinduced electron transfer, the efficiency of which is modulated by the presence of the insulating silica matrix. PMID:26956128

  19. Cellulose conjugated FITC-labelled mesoporous silica nanoparticles: intracellular accumulation and stimuli responsive doxorubicin release

    NASA Astrophysics Data System (ADS)

    Hakeem, Abdul; Zahid, Fouzia; Duan, Ruixue; Asif, Muhammad; Zhang, Tianchi; Zhang, Zhenyu; Cheng, Yong; Lou, Xiaoding; Xia, Fan

    2016-02-01

    Herein, we design novel cellulose conjugated mesoporous silica nanoparticle (CLS-MSP) based nanotherapeutics for stimuli responsive intracellular doxorubicin (DOX) delivery. DOX molecules are entrapped in pores of the fabricated mesoporous silica nanoparticles (MSPs) while cellulose is used as an encapsulating material through esterification on the outlet of the pores of the MSPs to avoid premature DOX release under physiological conditions. In in vitro studies, stimuli responsive DOX release is successfully achieved from DOX loaded cellulose conjugated mesoporous silica nanoparticles (DOX/CLS-MSPs) by pH and cellulase triggers. Intracellular accumulation of DOX/CLS-MSPs in human liver cancer cells (HepG2 cells) is investigated through confocal microscope magnification. Cell viability of HepG2 cells is determined as the percentage of the cells incubated with DOX/CLS-MSPs compared with that of non-incubated cells through an MTT assay.Herein, we design novel cellulose conjugated mesoporous silica nanoparticle (CLS-MSP) based nanotherapeutics for stimuli responsive intracellular doxorubicin (DOX) delivery. DOX molecules are entrapped in pores of the fabricated mesoporous silica nanoparticles (MSPs) while cellulose is used as an encapsulating material through esterification on the outlet of the pores of the MSPs to avoid premature DOX release under physiological conditions. In in vitro studies, stimuli responsive DOX release is successfully achieved from DOX loaded cellulose conjugated mesoporous silica nanoparticles (DOX/CLS-MSPs) by pH and cellulase triggers. Intracellular accumulation of DOX/CLS-MSPs in human liver cancer cells (HepG2 cells) is investigated through confocal microscope magnification. Cell viability of HepG2 cells is determined as the percentage of the cells incubated with DOX/CLS-MSPs compared with that of non-incubated cells through an MTT assay. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08753h

  20. Anomalous increase in the magnetorheological properties of magnetic fluid induced by silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Desai, Rucha; Upadhyay, R. V.

    2014-12-01

    Magnetorheological properties are experimentally investigated in aqueous magnetic fluid containing spherical silica nanoparticles. A bi-dispersed system is prepared using aqueous suspension of silica nanoparticles and aqueous magnetic fluid. Both these fluids exhibit Newtonian viscosity with nominal values of 1.3 and 5.8 mPa\\cdot s at 20 °C. Three different samples are prepared by varying silica and magnetic fluid concentrations and keeping the total volume constant. The addition of silica nanoparticles leads to enhancement of the magnetic field induced viscosity up to the order 107 Pa\\cdot s. The magnetic field induced viscosity is analyzed using the structural viscosity model. Magnetic field induced static and dynamic yield stress values to reveal the existence of field induced clustering. An attempt is made to explain this yielding behavior using chain-like and micromechanical models. It is found that high silica fraction leads to the formation of chain-like structure. At low silica fraction, chains overlap and result into layer aggregates, which are responsible for the anomalous increase in the magnetorheological properties. This is further confirmed using magnetic field microscopic chain formations.

  1. Morphology controlling method for amorphous silica nanoparticles and jellyfish-like nanowires and their luminescence properties

    NASA Astrophysics Data System (ADS)

    Liu, Haitao; Huang, Zhaohui; Huang, Juntong; Xu, Song; Fang, Minghao; Liu, Yan-Gai; Wu, Xiaowen; Zhang, Shaowei

    2016-03-01

    Uniform silica nanoparticles and jellyfish-like nanowires were synthesized by a chemical vapour deposition method on Si substrates treated without and with Ni(NO3)2, using silicon powder as the source material. Composition and structural characterization using field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and fourier-transform infrared spectroscopy showed that the as-prepared products were silica nanoparticles and nanowires which have amorphous structures. The form of nanoparticles should be related to gas-phase nucleation procedure. The growth of the nanowires was in accordance with vapour-liquid-solid mechanism, followed by Ostwald ripening to form the jellyfish-like morphology. Photoluminescence and cathodoluminescence measurements showed that the silica products excited by different light sources show different luminescence properties. The emission spectra of both silica nanoparticles and nanowires are due to the neutral oxygen vacancies (≡Si-Si≡). The as-synthesized silica with controlled morphology can find potential applications in future nanodevices with tailorable photoelectric properties.

  2. Effect of Silica Nanoparticles on the Photoluminescence Properties of BCNO Phosphor

    NASA Astrophysics Data System (ADS)

    Nuryadin, Bebeh W.; Faryuni, Irfana Diah; Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal, Khairurrijal

    2011-12-01

    Effect of additional silica nanoparticles on the photoluminescence (PL) performance of boron carbon oxy-nitride (BCNO) phosphor was investigated. As a precursor, boric acid and urea were used as boron and nitrogen sources, respectively. The carbon sources was polyethylene glycol (PEG) with average molecule weight 20000 g/mol.. Precursor solutions were prepared by mixing these raw materials in pure water, followed by stirring to achieve homogeneous solutions. In this precursor, silica nanoparticles were added at various mass ratio from 0 to 7 %wt in the solution. The precursors were then heated at 750 °C for 60 min in a ceramic crucible under atmospheric pressure. The photoluminescence (PL) spectrum that characterized by spectrophotometer showed a single, distinct, and broad emission band varied from blue to near red color, depend on the PEG, boric acid and urea ratio in the precursor. The addition of silica nanoparticles caused the increasing of PL intensity as well as the shifting of peak wavelength of PL spectrum. The peak shifting of PL was affected by the concentration of silica nanoparticles that added into the precursor. We believe that the BCNO-silica composite phosphor becomes a promising material for the phosphor conversion-based white light-emitting diodes.

  3. Morphology controlling method for amorphous silica nanoparticles and jellyfish-like nanowires and their luminescence properties.

    PubMed

    Liu, Haitao; Huang, Zhaohui; Huang, Juntong; Xu, Song; Fang, Minghao; Liu, Yan-Gai; Wu, Xiaowen; Zhang, Shaowei

    2016-01-01

    Uniform silica nanoparticles and jellyfish-like nanowires were synthesized by a chemical vapour deposition method on Si substrates treated without and with Ni(NO3)2, using silicon powder as the source material. Composition and structural characterization using field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and fourier-transform infrared spectroscopy showed that the as-prepared products were silica nanoparticles and nanowires which have amorphous structures. The form of nanoparticles should be related to gas-phase nucleation procedure. The growth of the nanowires was in accordance with vapour-liquid-solid mechanism, followed by Ostwald ripening to form the jellyfish-like morphology. Photoluminescence and cathodoluminescence measurements showed that the silica products excited by different light sources show different luminescence properties. The emission spectra of both silica nanoparticles and nanowires are due to the neutral oxygen vacancies (≡Si-Si≡). The as-synthesized silica with controlled morphology can find potential applications in future nanodevices with tailorable photoelectric properties. PMID:26940294

  4. Morphology controlling method for amorphous silica nanoparticles and jellyfish-like nanowires and their luminescence properties

    PubMed Central

    Liu, Haitao; Huang, Zhaohui; Huang, Juntong; Xu, Song; Fang, Minghao; Liu, Yan-gai; Wu, Xiaowen; Zhang, Shaowei

    2016-01-01

    Uniform silica nanoparticles and jellyfish-like nanowires were synthesized by a chemical vapour deposition method on Si substrates treated without and with Ni(NO3)2, using silicon powder as the source material. Composition and structural characterization using field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and fourier-transform infrared spectroscopy showed that the as-prepared products were silica nanoparticles and nanowires which have amorphous structures. The form of nanoparticles should be related to gas-phase nucleation procedure. The growth of the nanowires was in accordance with vapour-liquid-solid mechanism, followed by Ostwald ripening to form the jellyfish-like morphology. Photoluminescence and cathodoluminescence measurements showed that the silica products excited by different light sources show different luminescence properties. The emission spectra of both silica nanoparticles and nanowires are due to the neutral oxygen vacancies (≡Si-Si≡). The as-synthesized silica with controlled morphology can find potential applications in future nanodevices with tailorable photoelectric properties. PMID:26940294

  5. Silica nanoparticles and silver-doped silica nanoparticles induce endoplasmatic reticulum stress response and alter cytochrome P4501A activity.

    PubMed

    Christen, Verena; Fent, Karl

    2012-04-01

    Engineered silica nanoparticles (SiO(2)-NPs) find widespread application and may lead to exposure of humans and the environment. Here we compare the effects of SiO(2)-NPs and SiO(2)-NPs doped with silver (SiO(2)-Ag-NPs) on survival and cellular function of human liver cells (Huh7) and Pimephales promelas (fathead minnow) fibroblast cells (FMH). In Huh7 cells we investigate effects on the endoplasmatic reticulum (ER), including ER stress, and interactions of nanoparticles (NPs) with metabolizing enzymes and efflux transporters. The NPs formed agglomerates/aggregates in cell culture media as revealed by SEM and TEM. SiO(2) and SiO(2)-1% Ag-NPs were taken up into cells as demonstrated by agglomerates occurring in vesicular-like structures or freely dispersed in the cytosol. Cytotoxicity was more pronounced in Huh7 than in FMH cells, and increased with silver content in silver-doped NPs. Dissolved silver was the most significant factor for cytotoxicity. At toxic and non-cytotoxic concentrations SiO(2)-NPs and SiO(2)-1% Ag-NPs induced perturbations in the function of ER. In Huh7 cells NPs induced the unfolded protein response (UPR), or ER stress response, as demonstrated in induced expression of BiP and splicing of XBP1 mRNA, two selective markers of ER stress. Additionally, SiO(2)-1% Ag-NPs and AgNO(3) induced reactive oxygen species. Pre-treatment of Huh7 cells with SiO(2)-1% Ag-NPs followed by exposure to the inducer benzo(a)pyrene caused a significant reduced induction of CYP1A activity. NPs did not alter the activity of ABC transporters. These data demonstrate for the first time that SiO(2)-NPs and SiO(2)-1% Ag-NPs result in perturbations of the ER leading to the ER stress response. This represents a novel and significant cellular signalling pathway contributing to the cytotoxicity of NPs. PMID:22245057

  6. Gold nanoparticle decorated graphene oxide/silica composite stationary phase for high-performance liquid chromatography.

    PubMed

    Liang, Xiaojing; Wang, Xusheng; Ren, Haixia; Jiang, Shengxiang; Wang, Licheng; Liu, Shujuan

    2014-06-01

    In the initial phase of this study, graphene oxide (GO)/silica was fabricated by assembling GO onto the silica particles, and then gold nanoparticles (GNPs) were used to modify the GO/silica to prepare a novel stationary phase for high-performance liquid chromatography. The new stationary phase could be used in both reversed-phase chromatography and hydrophilic interaction liquid chromatography modes. Good separations of alkylbenzenes, isomerides, amino acids, nucleosides, and nucleobases were achieved in both modes. Compared with the GO/silica phase and GNPs/silica phase, it is found that except for hydrophilicity, large π-electron systems, hydrophobicity, and coordination functions, this new stationary phase also exhibited special separation performance due to the combination of 2D GO with zero-dimensional GNPs. PMID:24723561

  7. Coating thickness and coverage effects on the forces between silica nanoparticles in water.

    PubMed

    Salerno, K Michael; Ismail, Ahmed E; Lane, J Matthew D; Grest, Gary S

    2014-05-21

    The structure and interactions of coated silica nanoparticles have been studied in water using molecular dynamics simulations. For 5 nm diameter amorphous silica nanoparticles, we studied the effects of varying the chain length and grafting density of polyethylene oxide on the nanoparticle coating's shape and on nanoparticle-nanoparticle effective forces. For short ligands of length n = 6 and n = 20 repeat units, the coatings are radially symmetric while for longer chains (n = 100) the coatings are highly anisotropic. This anisotropy appears to be governed primarily by chain length, with coverage playing a secondary role. For the largest chain lengths considered, the strongly anisotropic shape makes fitting to a simple radial force model impossible. For shorter ligands, where the coatings are isotropic, we found that the force between pairs of nanoparticles is purely repulsive and can be fit to the form (R/2r(core) - 1)(-b) where R is the separation between the center of the nanoparticles, r(core) is the radius of the silica core, and b is measured to be between 2.3 and 4.1. PMID:24852560

  8. Growth of Fe-Pt Magnetic Nanoparticles on Silica Particles Modified with Organic Molecules

    NASA Astrophysics Data System (ADS)

    Kitamoto, Yoshitaka; Fuchigami, Teruaki; Namiki, Yoshihisa

    2013-11-01

    In the present paper, we describe the formation of an assembly composed of Fe-Pt magnetic nanoparticles on a template particle. The assembly is composed of a magnetic nanoshell for core/shell particles or hollow particles for application in nanomedicine devices. For this purpose, magnetic nanoparticles should be densely accumulated or deposited on template particles, Fe-Pt nanoparticles completely cover silica template particles by modifying them with a polymer such as poly(diallyldimethylammonium chloride) (PDDA), polyethyleneimine (PEI), or poly(N-vinyl-2-pyrrolidone) (PVP) followed by the polyol reduction of Fe and Pt compounds. Studies of their morphological, crystallographic, and magnetic properties reveal that Fe-Pt nanoparticles are selectively grown on the polymer-modified silica template particles; the polymer probably supplies nucleation sites for the formation of such nanoparticles. The species of polymer used strongly affects crystallographic and magnetic properties of the nanoparticles, particularly, the atomic ordering of Fe-Pt nanoparticles formed on silica template particles.

  9. Preparation and characterization of Ag nanoparticle-embedded blank and ligand-anchored silica gels.

    PubMed

    Im, Hee-Jung; Lee, Byung Cheol; Yeon, Jei-Won

    2013-11-01

    Ag nanoparticles, used for halogen (especially iodine) adsorption and an evaluation of halogen behavior, were embedded in synthesized inorganic-organic hybrid gels. In particular, an irradiation method using an electron beam plays a part in introducing Ag nanoparticles to the organofunctionalized silica gels from AgNO3 solutions in a simple way at atmospheric pressure and room temperature. For preparation of the Ag nanoparticle-embedded inorganic-organic hybrid gels, ligands of ethylenediamine (NH2CH2CH2NH-, TMSen) and mercapto (HS-) functionalized three-dimensional porous SiO2 sol-gels were first synthesized through hydrolysis and condensation reactions, and Ag nanoparticles were then embedded into the ethylenediamine- and mercapto-anchored silica gels each, through electron-beam irradiation. The addition of ligands yielded larger average pore sizes than the absence of any ligand. Moreover, the ethylenediamine ligand led to looser structures and better access of the Ag nanoparticles to the ethylenediamine-anchored gel. As a result, more Ag nanoparticles were introduced into the ethylenediamine-anchored gel. The preparation and characterization of Ag nanoparticle-embedded blank and ligand-anchored silica gels are discussed in detail. PMID:24245307

  10. EXAFS and DFT study of the cadmium and lead adsorption on modified silica nanoparticles.

    PubMed

    Arce, Valeria B; Gargarello, Romina M; Ortega, Florencia; Romañano, Virginia; Mizrahi, Martín; Ramallo-López, José M; Cobos, Carlos J; Airoldi, Claudio; Bernardelli, Cecilia; Donati, Edgardo R; Mártire, Daniel O

    2015-12-01

    Silica nanoparticles of 7 nm diameter were modified with (3-aminopropyl) triethoxysilane (APTES) and characterized by CP-MAS (13)C and (29)Si NMR, FTIR, zeta potential measurements, and thermogravimetry. The particles were shown to sorb successfully divalent lead and cadmium ions from aqueous solution. Lead complexation with these silica nanoparticles was clearly confirmed by EXAFS (Extended X-ray Absorption Fine Structure) with synchrotron light measurements. Predicted Pb-N and Pb-C distances obtained from quantum-chemical calculations are in very good agreement with the EXAFS determinations. The calculations also support the higher APTES affinity for Pb(2+) compared to Cd(2+). PMID:26135536

  11. Removal of mercury from aqueous solution using mesoporous silica nanoparticles modified with polyamide receptor.

    PubMed

    He, Chunsheng; Ren, Long; Zhu, Weiping; Xu, Yufang; Qian, Xuhong

    2015-11-15

    Based on the principle of supramolecular recognition and fluorescent chemical sensors, a novel kind of material for the separation of toxic heavy metal ions was designed and synthesized. Mesoporous silica nanoparticles MCM-41 with high surface areas and large ordered pores were used as the supporting matrix. Poly-amide derivative, was grafted to the mesoporous silica nanoparticles for extracting and separating trace Hg(2+) from aqueous solution, with a short adsorption time (t=3min) and a wide range of pH application (pH 3-11). The separation material could also extract trace mercury from Traditional Chinese Medicine, and has no influence on their effective components. PMID:26232282

  12. Incorporation of magnetite nanoparticle clusters in fluorescent silica nanoparticles for high-performance brain tumor delineation.

    PubMed

    Wan, Jiaqi; Meng, Xiangxi; Liu, Enzhong; Chen, Kezheng

    2010-06-11

    Bifunctional nanoprobes with both magnetic and optical contrast have been developed for ultra-sensitive brain tumor imaging at the cellular level. The nanoprobes were synthesized by simultaneously incorporating a magnetite nanoparticle cluster and fluorescence dyes into silica encapsulation by a sol-gel approach under ultrasonic treatment. The nanoprobes maintain superparamagnetic behavior at room temperature and possess enhanced transverse relaxivity and good photostability. As a glioma targeting ligand, chlorotoxin was covalently bonded to the surface of the nanoprobes. In vitro cellular uptake assays demonstrated that the nanoprobes were highly specific, taken up by human U251-MG glioma cells via receptor-mediated endocytosis. The labeled glioma cells were readily detectable by both MR imager and confocal laser scanning microscopy. PMID:20472942

  13. Hydroxyl density affects the interaction of fibrinogen with silica nanoparticles at physiological concentration.

    PubMed

    Marucco, Arianna; Turci, Francesco; O'Neill, Luke; Byrne, Hugh J; Fubini, Bice; Fenoglio, Ivana

    2014-04-01

    An increasing interest in the interaction between blood serum proteins and nanoparticles has emerged over the last years. In fact, this process plays a key role in the biological response to nanoparticles. The behavior of proteins at the biofluid/material interface is driven by the physico-chemical properties of the surface. However, much research is still needed to gain insight into the process at a molecular level. In this study, the effect of silanol density on the interaction of fibrinogen at physiological concentrations with silica nanoparticle/flat surfaces has been studied. Silica nanoparticles and silica wafers were modified and characterized to obtain a set of samples with different silanols density. The interaction with fibrinogen has been studied by evaluating the extent of coverage (bicinchoninic acid assay) and the irreversibility of adsorption (shift of the ζ potential). To clarify the molecular mechanism of fibrinogen/surface interactions, confocal micro-Raman spectroscopy (nanoparticles) and atomic force microscopy (wafers) were used. Finally the effect of fibrinogen on the agglomeration of nanoparticles has been evaluated by Flow Particle Image Analysis. The data reported here show that a minimal variation in the state of the silica surface modifies the adsorption behavior of fibrinogen, which appears mediated by a competition between protein/protein and protein/surface interactions. By comparing the data obtained on nanoparticles and silicon-supported silica layers, we found that hydrophilicity increases the tendency of fibrinogen molecules to interact with the surface rather than with other molecules, thus inhibiting fibrinogen self-assembly. This study contributes to the knowledge of the processes occurring at the surface/biological fluids interface, needed for the design of new biocompatible materials. PMID:24491335

  14. Robust antireflection coatings By UV cross-linking of silica nanoparticles and diazo-resin polycation

    NASA Astrophysics Data System (ADS)

    Ridley, Jason I.; Heflin, James R.; Ritter, Alfred L.

    2007-09-01

    Antireflection coatings have been fabricated by self-assembly using silica nanoparticles. The ionic self-assembled multilayer (ISAM) films are tightly packed and homogeneous. While the geometric properties of a matrix of spherical particles with corresponding void interstices are highly suitable to meet the conditions for minimal reflectivity, it is also a cause for the lack of cohesion within the constituent body, as well as to the substrate surface. This study investigates methods for improving the interconnectivity of the nanoparticle structure. One such method involves UV curing of diazo-resin (DAR)/silica nanoparticle films, thereby converting the ionic interaction into a stronger covalent bond. Factorial analysis and response surface methods are incorporated to determine factors that affect film properties, and to optimize their optical and adhesive capabilities. The second study looks at the adhesive strength of composite multilayer films. Films are fabricated with silica nanoparticles and poly(allylamine hydrochloride) (PAH), and dipped into aqueous solutions of PAH and poly(methacrylic acid, sodium salt) (PMA) to improve cohesion of silica nanoparticles in the matrix, as well as binding strength to the substrate surface. The results of the two studies are discussed.

  15. Chitosan-mediated formation of biomimetic silica nanoparticles: an effective method for manganese peroxidase immobilization and stabilization.

    PubMed

    Luan, Pan-Pan; Jiang, Yan-Jun; Zhang, Song-Ping; Gao, Jing; Su, Zhi-Guo; Ma, Guang-Hui; Zhang, Yu-Fei

    2014-11-01

    Our work here, for the first time, reported the use of chitosan-mediated biomimetic silica nanoparticles in enzyme immobilization. In order to make clear the relationship among silicification process, silica nanoparticle structure and immobilized enzyme activity, a mechanism of chitosan-mediated silicification using sodium silicate as the silica source was primarily evaluated. Chitosan was demonstrated effectively to promote the silicification not only in accelerating the aggregation rate of sodium silicate, but also in templating the formation of silica nanoparticles. Although the whole biomimetic silicification process contained polycondensation-aggregation-precipitation three stages, the elemental unit in precipitated silica was confirmed to be nanoparticles with 100 nm diameter regardless of the chitosan and silicate concentration used. Furthermore, the effect of enzyme on silicification process was also investigated. The introducing of manganese peroxidase (MnP) to silica precursor solution had no obvious effect on the silicification rate and nanoparticle morphology. The residual activity and embedding rate of immobilized MnP were 64.2% and 36.4% respectively under the optimum conditions. In addition, compared to native MnP, the MnP embedded in chitosan/silica nanoparticles exhibited improved stability against organic solvent and ultrasonic wave. After ultrasonic treatment for 20 min, 77% of the initial activity was remained due to the protective effect of chitosan/silica nanoparticles, while native MnP lost almost all of its original activity. PMID:24913823

  16. Effect of amino-modified silica nanoparticles on the corrosion protection properties of epoxy resin-silica hybrid materials.

    PubMed

    Chang, Kung-Chin; Lin, Hui-Fen; Lin, Chang-Yu; Kuo, Tai-Hung; Huang, Hsin-Hua; Hsu, Sheng-Chieh; Yeh, Jui-Ming; Yang, Jen-Chang; Yu, Yuan-Hsiang

    2008-06-01

    In this paper, a series of organic-inorganic hybrid materials consisting of epoxy resin frameworks and dispersed nanoparticles of amino-modified silica (AMS) were successfully prepared. First of all, the AMS nanoparticles were synthesized by carrying out the conventional acid-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) in the presence of (3-aminopropyl)-trimethoxysilane (APTES) molecules. The as-prepared AMS nanoparticles were then characterized by FTIR, 13C-NMR and 29Si-NMR spectroscopy. Subsequently, a series of hybrid materials were prepared by performing in-situ thermal ring-opening polymerization reactions of epoxy resin in the presence of as-prepared AMS nanoparticles and raw silica (RS) particles. The as-prepared epoxy-silica hybrid materials with AMS nanoparticles were found to show better dispersion capability than that of RS particles existed in hybrid materials based on the morphological observation of transmission electron microscopy (TEM). The hybrid materials containing AMS nanoparticles in the form of coating on cold-rolled steel (CRS) were found to be much superior in corrosion protection over those of hybrid materials with RS particles when tested by a series of electrochemical measurements of potentiodynamic and impedance spectroscopy in 5 wt% aqueous NaCI electrolyte. The increase of corrosion protection effect of hybrid coatings may have probably resulted from the enhancement of the adhesion strength of the hybrid coatings on CRS coupons, which may be attributed to the formation of Fe-O-Si covalent bond at the interface of coating/CRS system based on the FTIR-RAS (reflection absorption spectroscopy) studies. The better dispersion capability of AMS nanoparticles in hybrid materials were found to lead more effectively enhanced molecular barrier property, mechanical strength, surface hydrophobicity and optical clarity as compared to that of RS particles, in the form of coating and membrane, based on the measurements of molecular

  17. Observations on size confinement effect in B-C-N nanoparticles embedded in mesoporous silica channels

    SciTech Connect

    Tripathi, Neeti; Yamashita, Masaru; Akai, Tomoko; Uchida, Takeyuki

    2014-07-07

    Fluorescent B-C-N/silica nanoparticles were synthesized by solution impregnation method. Effect of B-C-N particle size on the optical properties was investigated by varying the silica pore sizes. Formation of B-C-N nanoparticles within the mesoporous matrix is confirmed by x-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. Furthermore, a remarkable blue-shift in emission peak centres with decreasing pore size in conjugation with band gap modification, ascribed to the size confinement effect. A detailed analysis of experimental results by theoretically defined confinement models demonstrates that the B-C-N nanoparticles in the size range of 3–13 nm falls within the confinement regime. This work demonstrated the experimental evidence of the size confinement effect in smaller size B-C-N nanoparticles.

  18. Self-organized patterning through the dynamic segregation of DNA and silica nanoparticles

    PubMed Central

    Joksimovic, Rastko; Watanabe, Shun; Riemer, Sven; Gradzielski, Michael; Yoshikawa, Kenichi

    2014-01-01

    Exotic pattern formation as a result of drying of an aqueous solution containing DNA and silica nanoparticles is reported. The pattern due to segregation was found to critically depend on the relative ratio of nanoparticles and DNA, as revealed by polarization microscopy, scanning electron microscopy, and fluorescence microscopy. The blurred radial pattern that is usually observed in the drying of a colloidal solution was shown to be vividly sharpened in the presence of DNA. Uniquely curved, crescent-shaped micrometer-scale domains are generated in regions that are rich in nanoparticles. The characteristic segregated patterns observed in the present study are interpreted in terms of a large aspect ratio between the persistence length (∼50 nm) and the diameter (∼2 nm) of double-stranded DNA, and the relatively small silica nanoparticles (radius: 5 nm). PMID:24413900

  19. H2-induced copper and silver nanoparticle precipitation inside sol-gel silica optical fiber preforms

    PubMed Central

    2012-01-01

    Ionic copper- or silver-doped dense silica rods have been prepared by sintering sol-gel porous silica xerogels doped with ionic precursors. The precipitation of Cu or Ag nanoparticles was achieved by heat treatment under hydrogen followed by annealing under air atmosphere. The surface plasmon resonance bands of copper and silver nanoparticles have been clearly observed in the absorption spectra. The spectral positions of these bands were found to depend slightly on the particle size, which could be tuned by varying the annealing conditions. Hence, transmission electron microscopy showed the formation of spherical copper nanoparticles with diameters in the range of 3.3 to 5.6 nm. On the other hand, in the case of silver, both spherical nanoparticles with diameters in the range of 3 to 6 nm and nano-rods were obtained. PMID:22937818

  20. Characterization of Electret Based on Inorganic-organic Nanocomposite Using Fluoropolymer and Silica Nanoparticles

    NASA Astrophysics Data System (ADS)

    Suzuki, M.; Shimokizaki, M.; Takahashi, T.; Yoshikawa, Y.; Aoyagi, S.

    2015-12-01

    An A novel electret based on inorganic-organic nano composite using fluoropolymer and silica nanoparticles was developed in this study. CYTOP® is used to fabricate the nanocomposite electret, which is one of fluoropolymer. Three kinds of silica nanoparticles dispersed in methyl ethyl ketone were employed. Each type of nanoparticles was mixed in the CYTOP or stuck between three layers of CYTOP. Then, negative charge was implanted by corona discharge method. The initial surface potential of the nanocomposite electret was higher than that of a control electret made of pure CYTOP. Additionally, time stability of those was also better than that of control electret. However, above mentioned properties of the mix-typed electret was worse than that of stuck-typed electret, because of discharging through aggregates composed of the nanoparticles.

  1. Cellular uptake, evolution, and excretion of silica nanoparticles in human cells

    NASA Astrophysics Data System (ADS)

    Chu, Zhiqin; Huang, Yuanjie; Tao, Qian; Li, Quan

    2011-08-01

    A systematic study on the interaction of silica nanoparticles (NPs) with human cells has been carried out in the present work. Endocytosis and exocytosis are identified as major pathways for NPs entering, and exiting the cells, respectively. Most of the NPs are found to be enclosed in membrane bounded organelles, which are fairly stable (against rupture) as very few NPs are released into the cytoplasm. The nanoparticle-cell interaction is a dynamic process, and the amount of NPs inside the cells is affected by both the amount and morphology (degree of aggregation) of NPs in the medium. These interaction characteristics determine the low cytotoxicity of SiO2 NPs at low feeding concentration.A systematic study on the interaction of silica nanoparticles (NPs) with human cells has been carried out in the present work. Endocytosis and exocytosis are identified as major pathways for NPs entering, and exiting the cells, respectively. Most of the NPs are found to be enclosed in membrane bounded organelles, which are fairly stable (against rupture) as very few NPs are released into the cytoplasm. The nanoparticle-cell interaction is a dynamic process, and the amount of NPs inside the cells is affected by both the amount and morphology (degree of aggregation) of NPs in the medium. These interaction characteristics determine the low cytotoxicity of SiO2 NPs at low feeding concentration. Electronic supplementary information (ESI) available: Low magnification TEM image of 400 nm amorphous silica NPs; TEM images depicting the evolution process of 50 nm silica NPs inside cells; Confocal microscopy images showing the interaction of silica NPs with cells; ζ potential of NPs in dispersion with different pH value; MTT results of H1299 and NE083 cells incubated with 400 nm and 10-20 nm amorphous silica NPs and light microscopy images of H1299 cells treated with 50 nm silica NPs. See DOI: 10.1039/c1nr10499c

  2. Amorphous silica nanoparticles enhance cross-presentation in murine dendritic cells

    SciTech Connect

    Hirai, Toshiro; Yoshioka, Yasuo; Takahashi, Hideki; Ichihashi, Ko-ichi; Yoshida, Tokuyuki; Tochigi, Saeko; Nagano, Kazuya; Abe, Yasuhiro; Nabeshi, Hiromi; Yoshikawa, Tomoaki; Tsutsumi, Yasuo

    2012-10-26

    Highlights: Black-Right-Pointing-Pointer Silica nanoparticles enhanced cross-presentation. Black-Right-Pointing-Pointer Silica nanoparticles induced endosomal release of exogenous antigens. Black-Right-Pointing-Pointer Silica nanoparticle-induced cross-presentation was mediated by scavenger receptors. Black-Right-Pointing-Pointer Surface-modification may enable the manufacture of safer silica nanoparticles. -- Abstract: Nanomaterials (NMs) exhibit unique physicochemical properties and innovative functions, and they are increasingly being used in a wide variety of fields. Ensuring the safety of NMs is now an urgent task. Recently, we reported that amorphous silica nanoparticles (nSPs), one of the most widely used NMs, enhance antigen-specific cellular immune responses and may therefore aggravate immune diseases. Thus, to ensure the design of safer nSPs, investigations into the effect of nSPs on antigen presentation in dendritic cells, which are central orchestrators of the adaptive immune response, are now needed. Here, we show that nSPs with diameters of 70 and 100 nm enhanced exogenous antigen entry into the cytosol from endosomes and induced cross-presentation, whereas submicron-sized silica particles (>100 nm) did not. Furthermore, we show that surface modification of nSPs suppressed cross-presentation. Although further studies are required to investigate whether surface-modified nSPs suppress immune-modulating effects in vivo, the current results indicate that appropriate regulation of the characteristics of nSPs, such as size and surface properties, will be critical for the design of safer nSPs.

  3. Nanoparticle-based PARACEST agents: the quenching effect of silica nanoparticles on the CEST signal from surface-conjugated chelates.

    PubMed

    Evbuomwan, Osasere M; Merritt, Matthew E; Kiefer, Garry E; Dean Sherry, A

    2012-01-01

    Silica nanoparticles of average diameter 53 ± 3 nm were prepared using standard water-in-oil microemulsion methods. After conversion of the surface Si-OH groups to amino groups for further conjugation, the PARACEST agent, EuDOTA-(gly)₄ (-) was coupled to the amines via one or more side-chain carboxyl groups in an attempt to trap water molecules in the inner-sphere of the complex. Fluorescence and ICP analyses showed that approximately 1200 Eu(3+) complexes were attached to each silica nanoparticle, leaving behind excess protonated amino groups. CEST spectra of the modified silica nanoparticles showed that attachment of the EuDOTA-(gly)₄ (-) to the surface of the nanoparticles did not result in a decrease in water exchange kinetics as anticipated, but rather resulted in a complete elimination of the normal Eu(3+) -bound water exchange peak and broadening of the bulk water signal. This observation was traced to catalysis of proton exchange from the Eu(3+) -bound water molecule by excess positively charged amino groups on the surface of the nanoparticles. PMID:22344876

  4. Coupling gold nanoparticles to silica nanoparticles through disulfide bonds for glutathione detection

    NASA Astrophysics Data System (ADS)

    Shi, Yupeng; Zhang, Heng; Yue, Zhenfeng; Zhang, Zhaomin; Teng, Kar-Seng; Li, Mei-Jin; Yi, Changqing; Yang, Mengsu

    2013-09-01

    Advances in the controlled assembly of nanoscale building blocks have resulted in functional devices which can find applications in electronics, biomedical imaging, drug delivery etc. In this study, novel covalent nanohybrid materials based upon [Ru(bpy)3]2+-doped silica nanoparticles (SiNPs) and gold nanoparticles (AuNPs), which could be conditioned as OFF-ON probes for glutathione (GSH) detection, were designed and assembled in sequence, with the disulfide bonds as the bridging elements. The structural and optical properties of the nanohybrid architectures were characterized using transmission electron microscopy, UV-vis spectroscopy and fluorescence spectroscopy, respectively. Zeta potential measurements, x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were employed to monitor the reaction processes of the SiNPs-S-S-COOH and SiNPs-S-S-AuNPs synthesis. It was found that the covalent nanohybrid architectures were fluorescently dark (OFF state), indicating that SiNPs were effectively quenched by AuNPs. The fluorescence of the OFF-ON probe was resumed (ON state) when the bridge of the disulfide bond was cleaved by reducing reagents such as GSH. This work provides a new platform and strategy for GSH detection using covalent nanohybrid materials.

  5. Effects of silica nanoparticles on copper nanowire dispersions in aqueous PVA solutions

    NASA Astrophysics Data System (ADS)

    Lee, Seung Hak; Song, Hyeong Yong; Hyun, Kyu

    2016-05-01

    In this study, the effects of adding silica nanoparticles to PVA/CuNW suspensions were investigated rheologically, in particular, by small and large amplitude oscillatory shear (SAOS and LAOS) test. Interesting, the SAOS test showed the complex viscosities of CuNW/silica based PVA matrix were smaller than those of PVA/CuNW without silica. These phenomena show that nano-sized silica affects the dispersion of CuNW in aqueous PVA, which suggests small particles can prevent CuNW aggregation. Nonlinearity (third relative intensity ≡ I 3/1) was calculated from LAOS test results using Fourier Transform rheology (FT-rheology) and nonlinear linear viscoelastic ratio (NLR) value was calculated using the nonlinear parameter Q and complex modulus G*. Nonlinearity ( I 3/1) results showed more CuNW aggregation in PVA/CuNW without silica than in PVA/CuNW with silica. NLR (= [ Q 0( ϕ)/ Q 0(0)]/[ G*( ϕ)/ G*(0)]) results revealed an optimum concentration ratio of silica to CuNW to achieve a well-dispersed state. Degree of dispersion was assessed through the simple optical method. SAOS and LAOS test, and dried film morphologies showed nano-sized silica can improve CuNW dispersion in aqueous PVA solutions.

  6. Evaluation of silica nanoparticle toxicity after topical exposure for 90 days

    PubMed Central

    Ryu, Hwa Jung; Seong, Nak-won; So, Byoung Joon; Seo, Heung-sik; Kim, Jun-ho; Hong, Jeong-Sup; Park, Myeong-kyu; Kim, Min-Seok; Kim, Yu-Ri; Cho, Kyu-Bong; Seo, Mu Yeb; Kim, Meyoung-Kon; Maeng, Eun Ho; Son, Sang Wook

    2014-01-01

    Silica is a very common material that can be found in both crystalline and amorphous forms. Well-known toxicities of the lung can occur after exposure to the crystalline form of silica. However, the toxicities of the amorphous form of silica have not been thoroughly studied. The majority of in vivo studies of amorphous silica nanoparticles (NPs) were performed using an inhalation exposure method. Since silica NPs can be commonly administered through the skin, a study of dermal silica toxicity was necessary to determine any harmful effects from dermal exposures. The present study focused on the results of systemic toxicity after applying 20 nm colloidal silica NPs on rat skin for 90 days, in accordance with the Organization for Economic Cooperation and Development test guideline 411 with a good laboratory practice system. Unlike the inhalation route or gastrointestinal route, the contact of silica NPs through skin did not result in any toxicity or any change in internal organs up to a dose of 2,000 mg/kg in rats. PMID:25565831

  7. Evaluation of silica nanoparticle toxicity after topical exposure for 90 days.

    PubMed

    Ryu, Hwa Jung; Seong, Nak-won; So, Byoung Joon; Seo, Heung-sik; Kim, Jun-ho; Hong, Jeong-Sup; Park, Myeong-kyu; Kim, Min-Seok; Kim, Yu-Ri; Cho, Kyu-Bong; Seo, Mu Yeb; Kim, Meyoung-Kon; Maeng, Eun Ho; Son, Sang Wook

    2014-01-01

    Silica is a very common material that can be found in both crystalline and amorphous forms. Well-known toxicities of the lung can occur after exposure to the crystalline form of silica. However, the toxicities of the amorphous form of silica have not been thoroughly studied. The majority of in vivo studies of amorphous silica nanoparticles (NPs) were performed using an inhalation exposure method. Since silica NPs can be commonly administered through the skin, a study of dermal silica toxicity was necessary to determine any harmful effects from dermal exposures. The present study focused on the results of systemic toxicity after applying 20 nm colloidal silica NPs on rat skin for 90 days, in accordance with the Organization for Economic Cooperation and Development test guideline 411 with a good laboratory practice system. Unlike the inhalation route or gastrointestinal route, the contact of silica NPs through skin did not result in any toxicity or any change in internal organs up to a dose of 2,000 mg/kg in rats. PMID:25565831

  8. Template synthesis of precisely monodisperse silica nanoparticles within self-assembled organometallic spheres

    NASA Astrophysics Data System (ADS)

    Suzuki, Kosuke; Sato, Sota; Fujita, Makoto

    2010-01-01

    One of the key challenges in materials science is to control the size and shape of inorganic nanoparticles with a high degree of precision, as these parameters have a significant influence on the nanoparticles' properties and potential applications. Here, we describe the preparation of highly monodisperse silica nanoparticles smaller than 5 nm in diameter by using self-assembled, hollow, spherical compounds as `endo-templates'. These coordination complexes with pendant sugar groups lining their interiors-assembled from 12 metal ions and 24 bis-pyridyl ligands containing glucose substituents-acted as structurally well-defined templates for the sol-gel condensation of alkoxysilanes. The polydispersities of the silica nanoparticles made with this method approached unity, with Mw/Mn < 1.01. The component ligands are modified easily, which enables an accurate expansion of the coordination complex and the subsequent control of the monodisperse silica nanoparticles that span molecular weights of 5,000 to 31,000 Da (corresponding to 2-4 nm in diameter). This method could be applicable to the preparation of other inorganic nanoparticles.

  9. Surface engineering of silica nanoparticles for oral insulin delivery: characterization and cell toxicity studies.

    PubMed

    Andreani, Tatiana; Kiill, Charlene P; de Souza, Ana Luiza R; Fangueiro, Joana F; Fernandes, Lisete; Doktorovová, Slavomira; Santos, Dario L; Garcia, Maria L; Gremião, Maria Palmira D; Souto, Eliana B; Silva, Amélia M

    2014-11-01

    The present work aimed at studying the interaction between insulin and SiNP surfaced with mucoadhesive polymers (chitosan, sodium alginate or polyethylene glycol) and the evaluation of their biocompatibility with HepG2 and Caco-2 cell lines, which mimic in vivo the target of insulin-loaded nanoparticles upon oral administration. Thus, a systematic physicochemical study of the surface-modified insulin-silica nanoparticles (Ins-SiNP) using mucoadhesive polymers has been described. The surfacing of nanoparticle involved the coating of silica nanoparticles (SiNP) with different mucoadhesive polymers, to achieve high contact between the systems and the gut mucosa to enhance the oral insulin bioavailability. SiNP were prepared by a modified Stöber method at room temperature via hydrolysis and condensation of tetraethyl orthosilicate (TEOS). Interaction between insulin and nanoparticles was assessed by differential scanning calorimetry (DSC), X-ray and Fourier-transform infrared (FTIR) studies. The high efficiency of nanoparticles' coating resulted in more stable system. FTIR spectra of insulin-loaded nanoparticles showed amide absorption bands which are characteristic of α-helix content. In general, all developed nanoparticles demonstrated high biocompatible, at the tested concentrations (50-500 μg/mL), revealing no or low toxicity in the two human cancer cell lines (HepG2 and Caco-2). In conclusion, the developed insulin-loaded SiNP surfaced with mucoadhesive polymers demonstrated its added value for oral administration of proteins. PMID:25466464

  10. Magnetic properties of Ni nanoparticles embedded in silica matrix (KIT-6) synthesized via novel chemical route

    SciTech Connect

    Dalavi, Shankar B.; Panda, Rabi N.; Raja, M. Manivel

    2015-06-24

    Thermally stable Ni nanoparticles have been embedded in mesoporous silica matrix (KIT-6) via novel chemical reduction method by using superhydride as reducing agent. X-ray diffraction (XRD) study confirms that pure and embedded Ni nanoparticles crystallize in face centered cubic (fcc) structure. Crystallite sizes of pure Ni, 4 wt% and 8 wt% Ni in silica were estimated to be 6.0 nm, 10.4 nm and 10.5 nm, respectively. Morphology and dispersion of Ni in silica matrix were studied by scanning electron microscopy (SEM). Magnetic study shows enhancement of magnetic moments of Ni nanoparticles embedded in silica matrix compared with that of pure Ni. The result has been interpreted on the basis of size reduction and magnetic exchange effects. Saturation magnetization values for pure Ni, 4 wt% and 8 wt% Ni in silica were found to be 15.77 emu/g, 5.08 emu/g and 2.00 emu/g whereas coercivity values were 33.72 Oe, 92.47 Oe and 64.70 Oe, respectively. We anticipate that the observed magnetic properties may find application as soft magnetic materials.

  11. Surfactant templating effects on the encapsulation of iron oxide nanoparticles within silica microspheres.

    PubMed

    Zheng, Tonghua; Pang, Jiebin; Tan, Grace; He, Jibao; McPherson, Gary L; Lu, Yunfeng; John, Vijay T; Zhan, Jingjing

    2007-04-24

    Hollow silica microspheres encapsulating ferromagnetic iron oxide nanoparticles were synthesized by a surfactant-aided aerosol process and subsequent treatment. The cationic surfactant cetyltrimethyl ammonium bromide (CTAB) played an essential role in directing the structure of the composite. Translation from mesoporous silica particles to hollow particles was a consequence of increased loading of ferric species in the precursor solution and the competitive partitioning of CTAB between silicate and ferric colloids. The hypothesis was that CTAB preferentially adsorbed onto more positively charged ferric colloids under acidic conditions. At a critical Fe/Si ratio, most of the CTAB was adsorbed onto ferric colloids and coagulated the colloids to form larger clusters. During the aerosol process, a silica shell was first formed due to the preferred silicate condensation on the gas-liquid interface of the aerosol droplet. Subsequent drying concentrated the ferric clusters inside the silica shell and resulted in a silica shell/ferric core particle. Thermal treatment of the core shell particle led to encapsulation of a single iron oxide nanoparticle inside each silica hollow microsphere. PMID:17397201

  12. Aluminothermic reduction enabled synthesis of silicon hollow microspheres from commercialized silica nanoparticles for superior lithium storage.

    PubMed

    Zhou, Zheng-Wei; Liu, Yi-Tao; Xie, Xu-Ming; Ye, Xiong-Ying

    2016-06-28

    We report the aluminothermic reduction enabled synthesis of silicon hollow microspheres from commercialized silica nanoparticles by controlled transformation and organization. The synergistically integrated merits of a simple process and delicate structural design lay a basis for developing an industrially viable silicon anode with optimized electrochemical performances. PMID:27302245

  13. CD44-engineered mesoporous silica nanoparticles for overcoming multidrug resistance in breast cancer

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Liu, Ying; Wang, Shouju; Shi, Donghong; Zhou, Xianguang; Wang, Chunyan; Wu, Jiang; Zeng, Zhiyong; Li, Yanjun; Sun, Jing; Wang, Jiandong; Zhang, Longjiang; Teng, Zhaogang; Lu, Guangming

    2015-03-01

    Multidrug resistance is a major impediment for the successful chemotherapy in breast cancer. CD44 is over-expressed in multidrug resistant human breast cancer cells. CD44 monoclonal antibody exhibits anticancer potential by inhibiting proliferation and regulating P-glycoprotein-mediated drug efflux activity in multidrug resistant cells. Thereby, CD44 monoclonal antibody in combination with chemotherapeutic drug might be result in enhancing chemosensitivity and overcoming multidrug resistance. The purpose of this study is to investigate the effects of the CD44 monoclonal antibody functionalized mesoporous silica nanoparticles containing doxorubicin on human breast resistant cancer MCF-7 cells. The data showed that CD44-modified mesoporous silica nanoparticles increased cytotoxicity and enhanced the downregulation of P-glycoprotein in comparison to CD44 antibody. Moreover, CD44-engineered mesoporous silica nanoparticles provided active target, which promoted more cellular uptake of DOX in the resistant cells and more retention of DOX in tumor tissues than unengineered counterpart. Animal studies of the resistant breast cancer xenografts demonstrated that CD44-engineered drug delivery system remarkably induced apoptosis and inhibited the tumor growth. Our results indicated that the CD44-engineered mesoporous silica nanoparticle-based drug delivery system offers an effective approach to overcome multidrug resistance in human breast cancer.

  14. A fluorescence ratiometric nano-pH sensor based on dual-fluorophore-doped silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Gao, Feng; Tang, Lijuan; Dai, Lu; Wang, Lun

    2007-06-01

    We have synthesized dual-fluorophore-doped core-shell silica nanoparticles used as ratiometric pH sensor. The nanoparticles were prepared with a reverse microemulsion technique by simultaneously encapsulating two different fluorophores, the pH-sensitive dye fluorescein as a pH indicator and the pH-insensitive dye phenosafranine as an internal reference for fluorescence ratiometric measurement, into silica shell. The nanoparticles prevent the fluorescence dyes leaching from the silica matrix when immersed inside water. The hydrophilic silica shells were made by hydrolysing and polymerizing tetraethoxysilane (TEOS) in water-in-oil microemulsion. The fluorescence intensity ratio of the two dyes varied linearly as a function of pH in the range from 4.0 to 8.0. The sensor was also applied to measure pH of real water samples. The results are in good agreements with that using the conventional glass electrode method. The as-prepared fluorescent nanoparticles showed rapid response, excellent stability and high reproducibility as pH sensors.

  15. Impregnated silica nanoparticles for the reactive removal of sulphur mustard from solutions.

    PubMed

    Singh, Beer; Saxena, Amit; Nigam, Anil Kumar; Ganesan, Kumaran; Pandey, Pratibha

    2009-01-30

    High surface area (887.3m(2)/g) silica nanoparticles were synthesized using aerogel route and thereafter, characterized by N(2)-Brunauer-Emmet-Teller (BET), SEM and TEM techniques. The data indicated the formation of nanoparticles of silica in the size range of 24-75 nm with mesoporous characteristics. Later, these were impregnated with reactive chemicals such as N-chloro compounds, oxaziridines, polyoxometalates, etc., which have already been proven to be effective against sulphur mustard (HD). Thus, developed novel mesoporous reactive sorbents were tested for their self-decontaminating feature by conducting studies on kinetics of adsorptive removal of HD from solution. Trichloroisocyanuric acid impregnated silica nanoparticles (10%, w/w)-based system was found to be the best with least half-life value (t(1/2)=2.8 min) among prepared systems to remove and detoxify HD into nontoxic degradation products. Hydrolysis, dehydrohalogenation and oxidation reactions were found to be the route of degradation of HD over prepared sorbents. The study also inferred that 10% loading of impregnants over high surface area and low density silica nanoparticles enhances the rate of reaction kinetics and seems to be useful in the field of heterogeneous reaction kinetics. PMID:18513865

  16. Ionic liquid decorated mesoporous silica nanoparticles: a new high-performance hybrid electrolyte for lithium batteries.

    PubMed

    Li, Yang; Wong, Ka-Wai; Ng, Ka-Ming

    2016-03-10

    We report a novel hybrid electrolyte based on mesoporous silica nanoparticles decorated with an ionic liquid, which exhibits a superior lithium ion transference number of >0.8, and an excellent electrochemical window of >5 V with attractive ionic conductivity. The insights obtained pave a new way for the preparation of high-performance electrolytes with mesoporous structures. PMID:26926805

  17. Cell-specific intracellular anticancer drug delivery from mesoporous silica nanoparticles with pH sensitivity.

    PubMed

    Luo, Zhong; Cai, Kaiyong; Hu, Yan; Zhang, Beilu; Xu, Dawei

    2012-05-01

    A nanoreservoir for efficient intracellular anticancer drug delivery based on mesoporous silica nanoparticles end-capped with lactobionic acid-grafted bovine serum albumin is fabricated. It demonstrates great potential for both cell-specific endocytosis and intracellular pH-responsive controlled release of drugs. A possible endocytosis pathway/mechanism of the smart controlled drug release system is proposed. PMID:23184747

  18. Monodisperse metal nanoparticle catalysts on silica mesoporous supports: synthesis, characterizations, and catalytic reactions

    SciTech Connect

    Somorjai, G.A.

    2009-09-14

    The design of high performance catalyst achieving near 100% product selectivity at maximum activity is one of the most important goals in the modern catalytic science research. To this end, the preparation of model catalysts whose catalytic performances can be predicted in a systematic and rational manner is of significant importance, which thereby allows understanding of the molecular ingredients affecting the catalytic performances. We have designed novel 3-dimensional (3D) high surface area model catalysts by the integration of colloidal metal nanoparticles and mesoporous silica supports. Monodisperse colloidal metal NPs with controllable size and shape were synthesized using dendrimers, polymers, or surfactants as the surface stabilizers. The size of Pt, and Rh nanoparticles can be varied from sub 1 nm to 15 nm, while the shape of Pt can be controlled to cube, cuboctahedron, and octahedron. The 3D model catalysts were generated by the incorporation of metal nanoparticles into the pores of mesoporous silica supports via two methods: capillary inclusion (CI) and nanoparticle encapsulation (NE). The former method relies on the sonication-induced inclusion of metal nanoparticles into the pores of mesoporous silica, whereas the latter is performed by the encapsulation of metal nanoparticles during the hydrothermal synthesis of mesoporous silica. The 3D model catalysts were comprehensively characterized by a variety of physical and chemical methods. These catalysts were found to show structure sensitivity in hydrocarbon conversion reactions. The Pt NPs supported on mesoporous SBA-15 silica (Pt/SBA-15) displayed significant particle size sensitivity in ethane hydrogenolysis over the size range of 1-7 nm. The Pt/SBA-15 catalysts also exhibited particle size dependent product selectivity in cyclohexene hydrogenation, crotonaldehyde hydrogenation, and pyrrole hydrogenation. The Rh loaded SBA-15 silica catalyst showed structure sensitivity in CO oxidation reaction. In

  19. Deposition of gold nanoparticles on silica spheres by electroless metal plating technique.

    PubMed

    Kobayashi, Yoshio; Tadaki, Yohei; Nagao, Daisuke; Konno, Mikio

    2005-03-15

    A previously proposed method for metal deposition with silver [Kobayashi et al., Chem. Mater. 13 (2001) 1630] was extended to uniform deposition of gold nanoparticles on submicrometer-sized silica spheres. The present method consisted of three steps: (1) the adsorption of Sn(2+) ions took place on surface of silica particles, (2) Ag(+) ions added were reduced and simultaneously adsorbed to the surface, while Sn(2+) was oxidized to Sn(4+), and (3) Au(+) ions added were reduced and deposited on the Ag surface. TEM observation, X-ray diffractometry, and UV-vis absorption spectroscopy revealed that gold metal nanoparticles with an average particle size of 13 nm and a crystal size of 5.1 nm were formed on the silica spheres with a size of 273 nm at an Au concentration of 0.77 M. PMID:15721938

  20. The influence of applied silica nanoparticles on a bio-renewable castor oil based polyurethane nanocomposite and its physicochemical properties.

    PubMed

    Seeni Meera, Kamal Mohamed; Murali Sankar, Rajavelu; Paul, Jaya; Jaisankar, Sellamuthu N; Mandal, Asit Baran

    2014-05-28

    Novel bio-renewable castor oil based polyurethane (PU)-silica nanocomposite films were prepared using castor oil, 1,6-hexamethylene diisocyanate and dibutyltin dilaurate in tetrahydrofuran at room temperature. ATR-FTIR spectra confirm the formation of polyurethane and the presence of silica nanoparticles in the polyurethane matrix. The increase of Si nanoparticle content shifts the peak position of N-H and C[double bond, length as m-dash]O (both hydrogen and non-hydrogen bonded) groups present in the polyurethane structure. Furthermore, Raman spectra confirmed the urethane-amide interaction present in the polyurethane-silica nanocomposites. (29)Si CP/MAS NMR spectra evidence the formation and the presence of completely condensed SiO2 species in the polyurethane nanocomposite films. The incorporation of silica nanoparticles increases the thermal stability of the above-mentioned polyurethane films, which can be seen from the increase in activation energy (Ea) values of the degradation process. The Ea values at two stages (Tmax1 and Tmax2) of the degradation process are 133, 139 and 157, 166 kJ mol(-1) for PU control and PU-5AMS (5 wt% amine modified silica nanoparticles), respectively. DSC results prove the interfacial interaction present between silica nanoparticles and the polyurethane hard segment, which decreases the melting temperature. Optical transmittance of the polyurethane films decreased with increasing silica content due to the scattering at the interfaces between the silica nanoparticles and polyurethane. It is interesting to note that the presence of silica nanoparticles gives reinforcement to polyurethane film, thereby increasing the storage modulus up to 24% for PU-5AMS. FE-SEM and HR-TEM images confirm the presence of silica nanoparticles in the polyurethane matrix. PMID:24714842

  1. Silica aerogel-polymer nanocomposites and new nanoparticle syntheses

    NASA Astrophysics Data System (ADS)

    Boday, Dylan Joseph

    Aerogels are extremely high surface area, low density materials with applications including thermal and acoustic insulators, radiation detectors and cometary dust particle traps. However, their low density and aggregate structure makes them extremely fragile and practically impossible to machine or handle without breaking. This has led to the development of aerogel composites with enhanced mechanical properties through the addition of polymers or surface modifiers. To date, attempts to strengthen aerogels have come with significant increases in density and processing time. Here I will describe our search for a solution to these problems with our invention using methyl cyanoacrylate chemical vapor deposition (CVD) to strengthen silica, aminated silica and bridged polysilsesquioxane aerogels. This approach led to a strength improvement of the composites within hours and the strongest composite prepared had a 100x strength improvement over the precursor aerogel. We also developed the first approach to control the molecular weight of the polymers that reinforce silica aerogels using surface-initiated atom transfer radical polymerization (SI-ATRP). Although PMMA reinforcement of silica aerogels improved the mechanical properties, further strength improvements were achieved by cross-linking the grafted PMMA. Additionally, we developed the first silica aerogels reinforced with polyaniline nanofibers that were strong and electrically conductive. Reinforcing silica aerogels with polyaniline allowed them to be used as a sensor for the detection of protonating and deprotonating gaseous species. Finally we developed a new approach for the synthesis of silica and bridged polysilsesquioxane spheres using a surfactant free synthesis. This approach allowed for the first in-situ incorporation of base sensitive functionalities during the sol-gel polymerization.

  2. Growth of gold nanoparticles at gelatin-silica bio-interfaces

    NASA Astrophysics Data System (ADS)

    Bensaid, Imen; Masse, Sylvie; Selmane, Mohamed; Fessi, Shemseddine; Coradin, Thibaud

    2016-01-01

    The growth of gold nanoparticles via chemical reduction of HAuCl4 dispersed in gelatin-silicate mixtures was studied. Gelatin leads to densely packed nanoparticles whereas open colloidal aggregates with tight boundaries are formed within silica. Within the bio-hybrid systems, gold species are located within the gelatin-silicate particles and/or within the gelatin phase, depending on the preparation conditions. These various localizations and their impact on the final nanoparticle structure are discussed considering attractive and repulsive electrostatic interactions existing between the three components. These data suggest that bio-hybrid systems are interesting and versatile interfaces to study crystallization processes in confined environments.

  3. Aerosol Droplet Delivery of Mesoporous Silica Nanoparticles: A Strategy for Respiratory-Based Therapeutics

    PubMed Central

    Li, Xueting; Xue, Min; Raabe, Otto G.; Aaron, Holly L.; Eisen, Ellen A.; Evans, James E.; Hayes, Fred A.; Inaga, Sumire; Tagmout, Abderrahmane; Takeuchi, Minoru; Vulpe, Chris; Zink, Jeffrey I.; Risbud, Subhash H.; Pinkerton, Kent E.

    2015-01-01

    A highly versatile nanoplatform that couples mesoporous silica nanoparticles (MSN) with an aerosol technology to achieve direct nanoscale delivery to the respiratory tract is described. This novel method can deposit MSN nanoparticles throughout the entire respiratory tract, including nasal, tracheobronchial and pulmonary regions using a water-based aerosol. This delivery method was successfully tested in mice by inhalation. The MSN nanoparticles used have the potential for carrying and delivering therapeutic agents to highly specific target sites of the respiratory tract. The approach provides a critical foundation for developing therapeutic treatment protocols for a wide range of diseases where aerosol delivery to the respiratory system would be desirable. PMID:25819886

  4. High-Aluminum-Affinity Silica Is a Nanoparticle That Seeds Secondary Aluminosilicate Formation

    PubMed Central

    Jugdaohsingh, Ravin; Brown, Andy; Dietzel, Martin; Powell, Jonathan J.

    2013-01-01

    Despite the importance and abundance of aluminosilicates throughout our natural surroundings, their formation at neutral pH is, surprisingly, a matter of considerable debate. From our experiments in dilute aluminum and silica containing solutions (pH ~ 7) we previously identified a silica polymer with an extraordinarily high affinity for aluminium ions (high-aluminum-affinity silica polymer, HSP). Here, further characterization shows that HSP is a colloid of approximately 2.4 nm in diameter with a mean specific surface area of about 1,000 m2 g-1 and it competes effectively with transferrin for Al(III) binding. Aluminum binding to HSP strongly inhibited its decomposition whilst the reaction rate constant for the formation of the β-silicomolybdic acid complex indicated a diameter between 3.6 and 4.1 nm for these aluminum-containing nanoparticles. Similarly, high resolution microscopic analysis of the air dried aluminum-containing silica colloid solution revealed 3.9 ± 1.3 nm sized crystalline Al-rich silica nanoparticles (ASP) with an estimated Al:Si ratio of between 2 and 3 which is close to the range of secondary aluminosilicates such as imogolite. Thus the high-aluminum-affinity silica polymer is a nanoparticle that seeds early aluminosilicate formation through highly competitive binding of Al(III) ions. In niche environments, especially in vivo, this may serve as an alternative mechanism to polyhydroxy Al(III) species binding monomeric silica to form early phase, non-toxic aluminosilicates. PMID:24349573

  5. Passive mass transport for direct and quantitative SERS detection using purified silica encapsulated metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Shrestha, Binaya Kumar

    This thesis focuses on understanding implications of nanomaterial quality control and mass transport through internally etched silica coated nanoparticles for direct and quantitative molecular detection using surface enhanced Raman scattering (SERS). Prior to use, bare nanoparticles (partially or uncoated with silica) are removal using column chromatography to improve the quality of these nanomaterials and their SERS reproducibility. Separation of silica coated nanoparticles with two different diameters is achieved using Surfactant-free size exclusion chromatography with modest fractionation. Next, selective molecular transport is modeled and monitored using SERS and evaluated as a function of solution ionic strength, pH, and polarity. Molecular detection is achieved when the analytes first partition through the silica membrane then interact with the metal surface at short distances (i.e., less than 2 nm). The SERS intensities of unique molecular vibrational modes for a given molecule increases as the number of molecules that bind to the metal surface increases and are enhanced via both chemical and electromagnetic enhancement mechanisms as long as the vibrational mode has a component of polarizability tensor along the surface normal. SERS signals increase linearly with molecular concentration until the three-dimensional SERS-active volume is saturated with molecules. Implications of molecular orientation as well as surface selection rules on SERS intensities of molecular vibrational modes are studied to improve quantitative and reproducible SERS detection using internally etched Ag Au SiO2 nanoparticles. Using the unique vibrational modes, SERS intensities for p-aminothiophenol as a function of metal core compositions and plasmonics are studied. By understanding molecular transport mechanisms through internally etched silica matrices coated on metal nanoparticles, important experimental and materials design parameters are learned, which can be subsequently applied

  6. Study of Mesoporous Silica Nanoparticles' (MSNs) intracellular trafficking and their application as drug delivery vehicles

    NASA Astrophysics Data System (ADS)

    Yanes, Rolando Eduardo

    Mesoporous silica nanoparticles (MSNs) are attractive drug delivery vehicle candidates due to their biocompatibility, stability, high surface area and efficient cellular uptake. In this dissertation, I discuss three aspects of MSNs' cellular behavior. First, MSNs are targeted to primary and metastatic cancer cell lines, then their exocytosis from cancer cells is studied, and finally they are used to recover intracellular proteins. Targeting of MSNs to primary cancer cells is achieved by conjugating transferrin on the surface of the mesoporous framework, which resulted in enhancement of nanoparticle uptake and drug delivery efficacy in cells that overexpress the transferrin receptor. Similarly, RGD peptides are used to target metastatic cancer cell lines that over-express integrin alphanubeta3. A circular RGD peptide is bound to the surface of MSNs and the endocytosis and cell killing efficacy of camptothecin loaded nanoparticles is significantly improved in cells that express the target receptor. Besides targeting, I studied the ultimate fate of phosphonate coated mesoporous silica nanoparticles inside cells. I discovered that the nanoparticles are exocytosed from cells through lysosomal exocytosis. The nanoparticles are exocytosed in intact form and the time that they remain inside the cells is affected by the surface properties of the nanoparticles and the type of cells. Cells that have a high rate of lysosomal exocytosis excrete the nanoparticles rapidly, which makes them more resistant to drug loaded nanoparticles because the amount of drug that is released inside the cell is limited. When the exocytosis of MSNs is inhibited, the cell killing efficacy of nanoparticles loaded with camptothecin is enhanced. The discovery that MSNs are exocytosed by cells led to a study to determine if proteins could be recovered from the exocytosed nanoparticles. The procedure to isolate exocytosed zinc-doped iron core MSNs and identify the proteins bound to them was developed

  7. Preparation of silica coated cobalt ferrite magnetic nanoparticles for the purification of histidine-tagged proteins

    NASA Astrophysics Data System (ADS)

    Aygar, Gülfem; Kaya, Murat; Özkan, Necati; Kocabıyık, Semra; Volkan, Mürvet

    2015-12-01

    Surface modified cobalt ferrite (CoFe2O4) nanoparticles containing Ni-NTA affinity group were synthesized and used for the separation of histidine tag proteins from the complex matrices through the use of imidazole side chains of histidine molecules. Firstly, CoFe2O4 nanoparticles with a narrow size distribution were prepared in an aqueous solution using the controlled co-precipitation method. In order to obtain small CoFe2O4 agglomerates, oleic acid and sodium chloride were used as dispersants. The CoFe2O4 particles were coated with silica and subsequently the surface of these silica coated particles (SiO2-CoFe2O4) was modified by amine (NH2) groups in order to add further functional groups on the silica shell. Then, carboxyl (-COOH) functional groups were added to the SiO2-CoFe2O4 magnetic nanoparticles through the NH2 groups. After that Nα,Nα-Bis(carboxymethyl)-L-lysine hydrate (NTA) was attached to carboxyl ends of the structure. Finally, the surface modified nanoparticles were labeled with nickel (Ni) (II) ions. Furthermore, the modified SiO2-CoFe2O4 magnetic nanoparticles were utilized as a new system that allows purification of the N-terminal His-tagged recombinant small heat shock protein, Tpv-sHSP 14.3.

  8. In vitro developmental toxicity test detects inhibition of stem cell differentiation by silica nanoparticles

    SciTech Connect

    Park, Margriet V.D.Z. Annema, Wijtske; Salvati, Anna; Lesniak, Anna; Elsaesser, Andreas; Barnes, Clifford; McKerr, George; Howard, C. Vyvyan; Lynch, Iseult; Dawson, Kenneth A.; Piersma, Aldert H.; Jong, Wim H. de

    2009-10-01

    While research into the potential toxic properties of nanomaterials is now increasing, the area of developmental toxicity has remained relatively uninvestigated. The embryonic stem cell test is an in vitro screening assay used to investigate the embryotoxic potential of chemicals by determining their ability to inhibit differentiation of embryonic stem cells into spontaneously contracting cardiomyocytes. Four well characterized silica nanoparticles of various sizes were used to investigate whether nanomaterials are capable of inhibition of differentiation in the embryonic stem cell test. Nanoparticle size distributions and dispersion characteristics were determined before and during incubation in the stem cell culture medium by means of transmission electron microscopy (TEM) and dynamic light scattering. Mouse embryonic stem cells were exposed to silica nanoparticles at concentrations ranging from 1 to 100 {mu}g/ml. The embryonic stem cell test detected a concentration dependent inhibition of differentiation of stem cells into contracting cardiomyocytes by two silica nanoparticles of primary size 10 (TEM 11) and 30 (TEM 34) nm while two other particles of primary size 80 (TEM 34) and 400 (TEM 248) nm had no effect up to the highest concentration tested. Inhibition of differentiation of stem cells occurred below cytotoxic concentrations, indicating a specific effect of the particles on the differentiation of the embryonic stem cells. The impaired differentiation of stem cells by such widely used particles warrants further investigation into the potential of these nanoparticles to migrate into the uterus, placenta and embryo and their possible effects on embryogenesis.

  9. Predictable Heating and Positive MRI Contrast from a Mesoporous Silica-Coated Iron Oxide Nanoparticle.

    PubMed

    Hurley, Katie R; Ring, Hattie L; Etheridge, Michael; Zhang, Jinjin; Gao, Zhe; Shao, Qi; Klein, Nathan D; Szlag, Victoria M; Chung, Connie; Reineke, Theresa M; Garwood, Michael; Bischof, John C; Haynes, Christy L

    2016-07-01

    Iron oxide nanoparticles have great potential as diagnostic and therapeutic agents in cancer and other diseases; however, biological aggregation severely limits their function in vivo. Aggregates can cause poor biodistribution, reduced heating capability, and can confound their visualization and quantification by magnetic resonance imaging (MRI). Herein, we demonstrate that the incorporation of a functionalized mesoporous silica shell can prevent aggregation and enable the practical use of high-heating, high-contrast iron oxide nanoparticles in vitro and in vivo. Unmodified and mesoporous silica-coated iron oxide nanoparticles were characterized in biologically relevant environments including phosphate buffered saline, simulated body fluid, whole mouse blood, lymph node carcinoma of prostate (LNCaP) cells, and after direct injection into LNCaP prostate cancer tumors in nude mice. Once coated, iron oxide nanoparticles maintained colloidal stability along with high heating and relaxivity behaviors (SARFe = 204 W/g Fe at 190 kHz and 20 kA/m and r1 = 6.9 mM(-1) s(-1) at 1.4 T). Colloidal stability and minimal nonspecific cell uptake allowed for effective heating in salt and agarose suspensions and strong signal enhancement in MR imaging in vivo. These results show that (1) aggregation can lower the heating and imaging performance of magnetic nanoparticles and (2) a coating of functionalized mesoporous silica can mitigate this issue, potentially improving clinical planning and practical use. PMID:26991550

  10. Dye-Doped Silica Nanoparticle Labels/Protein Microarray for Detection of Protein Biomarkers

    SciTech Connect

    Wu, Hong; Huo, Qisheng; Varnum, Susan M.; Liu, Guodong; Wang, Jun; Nie, Zimin; Liu, Jun; Lin, Yuehe

    2008-10-20

    Biomarkers serve as indicators of biological and pathological processes, or physiological and pharmacological responses to a drug treatment. Interleukin-6 (IL-6), a biomarker with its important biological and pathological functions, has been studied for decades. Conventional fluorescence immunoassay has been widely used for analysis of biomakers like IL-6. However, single fluorophore labeling shows its limitations of low intensity and poor stability. We report a dye-encapsulated silica nanoparticle as a label, with the advantages of high fluorescence intensity, photostability, and biocompatibility, in conjunction with microarray technology for sensitive immunoassay of IL-6 on a microarray format. The tris (2,2’-bipyridyl)ruthenium (II)chloride hexahydrate (Rubpy) dye incorporated into silica nanoparticles using a simple one-step microemulsion synthesis step. The nanoparticles are uniform in size with a diameter of 50 nm. The microarray fluorescent immunoassay approach based on dye-doped silica nanoparticle labels has high sensitivity for practical applications with a limit of detection for IL-6 down to 0.1 ng mL-1. The calibration curve is linear over the range from 0.1 ng mL-1 to 10 ng mL-1. Furthermore, results illustrated that the assay is highly specific for IL-6 in the presence of range of cytokines or proteins. The RuDS dye-labeled nanoparticles in connection with protein microarrays show the promise for clinical diagnosis of biomarkers.

  11. The shape and size effects of polycation functionalized silica nanoparticles on gene transfection.

    PubMed

    Lin, Xinyi; Zhao, Nana; Yan, Peng; Hu, Hao; Xu, Fu-Jian

    2015-01-01

    Silica nanoparticles are attractive candidates for the development of safe and efficient non-viral gene carriers, owing to their controlled morphologies, potential of facile surface modification and excellent biocompatibility as well as in vivo biodegradability. Conversely, the size and shape of nanoparticles are considered to have an intense influence on their interaction with cells and biological systems, but the effects of particle size and shape on gene transfection are poorly understood. In this work, a series of novel gene carriers were designed employing polycation modified silica nanoparticles with five different morphologies, while keeping uniform zeta potential and surface functionality. Then the effects of particle size and shape of these five different carriers on gene transfection were investigated. The morphology of silica nanoparticles is demonstrated to play an important role in gene transfection, especially when the amount of polycation is low. Chiral nanorods with larger aspect ratio were found to fabricate the most efficient gene carriers with compromised cytotoxicity. It was also noted that hollow nanosphere-based carriers exhibited better gene transfection performance than did solid counterparts. These results may provide new strategies to develop promising gene carriers and useful information for the application of nanoparticles in biomedical areas. PMID:25219349

  12. Multifunctional mesoporous silica nanoparticles mediated co-delivery of paclitaxel and tetrandrine for overcoming multidrug resistance.

    PubMed

    Jia, Lejiao; Li, Zhenyu; Shen, Jingyi; Zheng, Dandan; Tian, Xiaona; Guo, Hejian; Chang, Ping

    2015-07-15

    The objective of the study is to fabricate multifunctional mesoporous silica nanoparticles for achieving co-delivery of conventional antitumor drug paclitaxel (PTX) and the multidrug resistance reversal agent tetrandrine (TET) expecting to overcome multidrug resistance of MCF-7/ADR cells. The nanoparticles were facile to prepare by self-assemble in situ drug loading approach. Namely, PTX and TET were solubilized in the cetyltrimethylammonium bromide (CTAB) micelles and simultaneously silica resources hydrolyze and condense to form nanoparticles. The obtained nanoparticles, denoted as PTX/TET-CTAB@MSN, exhibited pH-responsive release property with more easily released in the weak acidic environment. Studies on cellular uptake of nanoparticles demonstrated TET could markedly increase intracellular accumulation of nanoparticles. Furthermore, the PTX/TET-CTAB@MSN suppressed tumor cells growth more efficiently than only delivery of PTX (PTX-CTAB@MSN) or the free PTX. Moreover, the nanoparticle loading drugs with a PTX/TET molar ratio of 4.4:1 completely reversed the resistance of MCF-7/ADR cells to PTX and the resistance reversion index was 72.3. Mechanism research showed that both TET and CTAB could arrest MCF-7/ADR cells at G1 phase; and besides PTX arrested cells at G2 phase. This nanocarrier might have important potential in clinical implications for co-delivery of multiple drugs to overcome MDR. PMID:25956050

  13. Silica nanoparticle addition to control the calcium-leaching in cement-based materials

    NASA Astrophysics Data System (ADS)

    Gaitero, J. J.; Sáez de Ibarra, Y.; Erkizia, E.; Campillo, I.

    2006-05-01

    The calcium leaching of the cement hydrated matrix is of vital importance for constructions like water containers, dams, bridges, etc which have to be in contact with water during their lifetime. The aim of this work is the study of the reduction of such a negative phenomenon by the addition of silica nanoparticles. Several characterisation techniques such as 29Si MAS NMR, X-ray diffraction, mercury intrusion porosimetry and EDX-microanalysis have been used to evaluate the effect of the nanoparticles in the cement matrix nanostructure and in their impact on the evolution of the Ca leaching throughout time. Subsequent analysis of the results indicates that silica nanoparticles can reduce the Ca-leaching both decreasing the amount of portlandite in the matrix and controlling the degradation rate of the C-S-H gel.

  14. Kinetically-controlled synthesis of ultra-small silica nanoparticles and ultra-thin coatings

    NASA Astrophysics Data System (ADS)

    Ding, Tao; Yao, Lin; Liu, Cuicui

    2016-02-01

    The understanding of silica as a polymer-like globule allows us to synthesize ultra-small silica nanoparticles (NPs) via a kinetic controlled process. The synthetic system is quite simple with Tetraethyl orthosilicate (TESO) as the precursor and H2O as the solvent and reactant. The reaction conditions are gentle with a temperature of around 35 to 60 °C with an incubation time of 7-12 hours. The final product of the silica NPs is very uniform and could be as small as 10 nm. The silica NPs can further grow up to 18 nm under the controlled addition of the precursors. Also, these silica NPs can be used as seeds to generate larger silica NPs with sizes ranging from 20 to 100 nm, which can be a useful supplement to the size range made by the traditional Stöber method. Moreover, these ultra-small Au NPs can be used as a depletion reagent or as building blocks for an ultrathin silica coating, which has significant applications in fine-tuning the plasmons of AuNPs and thin spacers for surface enhanced spectroscopies.The understanding of silica as a polymer-like globule allows us to synthesize ultra-small silica nanoparticles (NPs) via a kinetic controlled process. The synthetic system is quite simple with Tetraethyl orthosilicate (TESO) as the precursor and H2O as the solvent and reactant. The reaction conditions are gentle with a temperature of around 35 to 60 °C with an incubation time of 7-12 hours. The final product of the silica NPs is very uniform and could be as small as 10 nm. The silica NPs can further grow up to 18 nm under the controlled addition of the precursors. Also, these silica NPs can be used as seeds to generate larger silica NPs with sizes ranging from 20 to 100 nm, which can be a useful supplement to the size range made by the traditional Stöber method. Moreover, these ultra-small Au NPs can be used as a depletion reagent or as building blocks for an ultrathin silica coating, which has significant applications in fine-tuning the plasmons of Au

  15. Functionalization and Characterization of Metal Oxide Coatings of Stainless Steel and Silica Nanoparticles

    NASA Astrophysics Data System (ADS)

    Slaney, Anne Margaret

    The development of tolerogens, fabricated devices eliciting tolerance toward incompatible donor ABO antigens in implant patients, is the ultimate goal of this project. This would permit ABO incompatible organ transplants, increase the donor pool for patients, increase efficiency in the use of available organs, reduce waitlist times and reduce mortality rates of patients. Stainless steel stents and silica nanoparticles were chosen as platforms for the stationary and circulating tolerogens. Stainless steel was coated with silica by solgel dip-coating, electrodeposition, and atomic layer deposition (ALD). The coatings were evaluated by CV, EIS, SEM, AFM, VASE, FTIR, XPS, and AES. Of the silica films, those deposited by ALD provided superior insulating, conformal, and thin coatings. These silica ALD films outperformed even titania ALD films upon stressing. Silica ALD films were subsequently functionalized with mixtures of silane derivatives of poly(ethylene glycol) (PEG), to prevent nonspecific protein binding, and monosaccharides (MS) or trisaccharide and tetrasaccharide (TS) antigens. Functionalizations were characterized by FTIR, XPS and UV-Vis following enzyme-linked lectin assays (ELLAs) or enzyme-linked immunosorbent assays (ELISAs). Effective functionalization allowing biological availability and activity even after incubation in blood plasma was confirmed. Microarray microscope slides were similarly developed with all ABO antigen subtypes, characterized by ToF-SIMS and ELISA, and proved useful in detecting antibodies in human blood samples. Silica nanoparticles, including fluorescent and magnetic varieties, in a range of sizes were prepared by sol-gel synthesis. The nanoparticles were evaluated by SEM, DLS, zeta potential measurements, fluorescence imaging, flow cytometry, two-photon excitation fluorescence correlation spectroscopy and TEM. Different dye incorporation methods were used for effective detection of NPs, and additional silica layers improved

  16. Efficient internalization of silica-coated iron oxide nanoparticles of different sizes by primary human macrophages and dendritic cells

    SciTech Connect

    Kunzmann, Andrea; Andersson, Britta; Vogt, Carmen; Feliu, Neus; Ye Fei; Gabrielsson, Susanne; Toprak, Muhammet S.; Buerki-Thurnherr, Tina; Laurent, Sophie; Vahter, Marie; Krug, Harald; Muhammed, Mamoun; Scheynius, Annika; Fadeel, Bengt

    2011-06-01

    Engineered nanoparticles are being considered for a wide range of biomedical applications, from magnetic resonance imaging to 'smart' drug delivery systems. The development of novel nanomaterials for biomedical applications must be accompanied by careful scrutiny of their biocompatibility. In this regard, particular attention should be paid to the possible interactions between nanoparticles and cells of the immune system, our primary defense system against foreign invasion. On the other hand, labeling of immune cells serves as an ideal tool for visualization, diagnosis or treatment of inflammatory processes, which requires the efficient internalization of the nanoparticles into the cells of interest. Here, we compare novel monodispersed silica-coated iron oxide nanoparticles with commercially available dextran-coated iron oxide nanoparticles. The silica-coated iron oxide nanoparticles displayed excellent magnetic properties. Furthermore, they were non-toxic to primary human monocyte-derived macrophages at all doses tested whereas dose-dependent toxicity of the smaller silica-coated nanoparticles (30 nm and 50 nm) was observed for primary monocyte-derived dendritic cells, but not for the similarly small dextran-coated iron oxide nanoparticles. No macrophage or dendritic cell secretion of pro-inflammatory cytokines was observed upon administration of nanoparticles. The silica-coated iron oxide nanoparticles were taken up to a significantly higher degree when compared to the dextran-coated nanoparticles, irrespective of size. Cellular internalization of the silica-coated nanoparticles was through an active, actin cytoskeleton-dependent process. We conclude that these novel silica-coated iron oxide nanoparticles are promising materials for medical imaging, cell tracking and other biomedical applications.

  17. Size-Tunable and Functional Core-Shell Structured Silica Nanoparticles for Drug Release

    SciTech Connect

    Chi, Fangli; Guo, Ya Nan; Liu, Jun; Liu, Yunling; Huo, Qisheng

    2010-02-18

    Size-tunable silica cross-linked micellar core-shell nanoparticles (SCMCSNs) were successfully synthesized from a Pluronic nonionic surfactant (F127) template system with organic swelling agents such as 1,3,5-trimethylbenzene (TMB) and octanoic acid at room temperature. The size and morphology of SCMCSNs were directly evidenced by TEM imaging and DLS measurements (up to ~90 nm). Pyrene and coumarin 153 (C153) were used as fluorescent probe molecules to investigate the effect and location of swelling agent molecules. Papaverine as a model drug was used to measure the loading capacity and release property of nanoparticles. The swelling agents can enlarge the nanoparticle size and improve the drug loading capacity of nanoparticles. Moreover, the carboxylic acid group of fatty acid can adjust the release behavior of the nanoparticles.

  18. (7)Be-recoil radiolabelling of industrially manufactured silica nanoparticles.

    PubMed

    Holzwarth, Uwe; Bellido, Elena; Dalmiglio, Matteo; Kozempel, Jan; Cotogno, Giulio; Gibson, Neil

    2014-01-01

    Radiolabelling of industrially manufactured nanoparticles is useful for nanoparticle dosimetry in biodistribution or cellular uptake studies for hazard and risk assessment. Ideally for such purposes, any chemical processing post production should be avoided as it may change the physico-chemical characteristics of the industrially manufactured species. In many cases, proton irradiation of nanoparticles allows radiolabelling by transmutation of a tiny fraction of their constituent atoms into radionuclides. However, not all types of nanoparticles offer nuclear reactions leading to radionuclides with adequate radiotracer properties. We describe here a process whereby in such cases nanoparticles can be labelled with (7)Be, which exhibits a physical half-life of 53.29 days and emits γ-rays of 478 keV energy, and is suitable for most radiotracer studies. (7)Be is produced via the proton-induced nuclear reaction (7)Li(p,n)(7)Be in a fine-grained lithium compound with which the nanoparticles are mixed. The high recoil energy of (7)Be atoms gives them a range that allows the (7)Be-recoils to be transferred from the lithium compound into the nanoparticles by recoil implantation. The nanoparticles can be recovered from the mixture by dissolving the lithium compound and subsequent filtration or centrifugation. The method has been applied to radiolabel industrially manufactured SiO2 nanoparticles. The process can be controlled in such a way that no alterations of the (7)Be-labelled nanoparticles are detectable by dynamic light scattering, X-ray diffraction and electron microscopy. Moreover, cyclotrons with maximum proton energies of 17-18 MeV that are available in most medical research centres could be used for this purpose. PMID:25285032

  19. Adsorption and stabilizing effects of highly-charged latex nanoparticles in dispersions of weakly-charged silica colloids.

    PubMed

    Herman, David; Walz, John Y

    2015-07-01

    An experimental study was undertaken to determine the effectiveness of using highly-charged nanoparticles as stabilizers for colloidal dispersions. The specific systems used here involved cationic (amidine) and anionic (sulfate) polystyrene latex nanoparticles with an approximate diameter of 20 nm and silica microparticles of diameter 1.0 μm, and experiments were conducted at the isoelectric point of the silica. It was found that while both types of nanoparticles adsorbed to the silica microparticles and increased the zeta potential to values where stability was expected, long term stability was not achieved, even at bulk nanoparticle concentrations as high as 0.5 vol.%. It is theorized that the incomplete coverage of the microparticles by the nanoparticles (i.e., surface coverage never exceeded 50%) allowed either direct contact between bare patches of the underlying microparticles or, alternatively, for nanoparticles adsorbed on one microparticle to bridge to bare spots on a neighboring microparticle. PMID:25498877

  20. Altered Gene Transcription in Human Cells Treated with Ludox® Silica Nanoparticles

    PubMed Central

    Fede, Caterina; Millino, Caterina; Pacchioni, Beniamina; Celegato, Barbara; Compagnin, Chiara; Martini, Paolo; Selvestrel, Francesco; Mancin, Fabrizio; Celotti, Lucia; Lanfranchi, Gerolamo; Mognato, Maddalena; Cagnin, Stefano

    2014-01-01

    Silica (SiO2) nanoparticles (NPs) have found extensive applications in industrial manufacturing, biomedical and biotechnological fields. Therefore, the increasing exposure to such ultrafine particles requires studies to characterize their potential cytotoxic effects in order to provide exhaustive information to assess the impact of nanomaterials on human health. The understanding of the biological processes involved in the development and maintenance of a variety of pathologies is improved by genome-wide approaches, and in this context, gene set analysis has emerged as a fundamental tool for the interpretation of the results. In this work we show how the use of a combination of gene-by-gene and gene set analyses can enhance the interpretation of results of in vitro treatment of A549 cells with Ludox® colloidal amorphous silica nanoparticles. By gene-by-gene and gene set analyses, we evidenced a specific cell response in relation to NPs size and elapsed time after treatment, with the smaller NPs (SM30) having higher impact on inflammatory and apoptosis processes than the bigger ones. Apoptotic process appeared to be activated by the up-regulation of the initiator genes TNFa and IL1b and by ATM. Moreover, our analyses evidenced that cell treatment with Ludox® silica nanoparticles activated the matrix metalloproteinase genes MMP1, MMP10 and MMP9. The information derived from this study can be informative about the cytotoxicity of Ludox® and other similar colloidal amorphous silica NPs prepared by solution processes. PMID:25170680

  1. Hemopexin as biomarkers for analyzing the biological responses associated with exposure to silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Higashisaka, Kazuma; Yoshioka, Yasuo; Yamashita, Kohei; Morishita, Yuki; Pan, Huiyan; Ogura, Toshinobu; Nagano, Takashi; Kunieda, Akiyoshi; Nagano, Kazuya; Abe, Yasuhiro; Kamada, Haruhiko; Tsunoda, Shin-ichi; Nabeshi, Hiromi; Yoshikawa, Tomoaki; Tsutsumi, Yasuo

    2012-10-01

    Practical uses of nanomaterials are rapidly spreading to a wide variety of fields. However, potential harmful effects of nanomaterials are raising concerns about their safety. Therefore, it is important that a risk assessment system is developed so that the safety of nanomaterials can be evaluated or predicted. Here, we attempted to identify novel biomarkers of nanomaterial-induced health effects by a comprehensive screen of plasma proteins using two-dimensional differential in gel electrophoresis (2D-DIGE) analysis. Initially, we used 2D-DIGE to analyze changes in the level of plasma proteins in mice after intravenous injection via tail veins of 0.8 mg/mouse silica nanoparticles with diameters of 70 nm (nSP70) or saline as controls. By quantitative image analysis, protein spots representing >2.0-fold alteration in expression were found and identified by mass spectrometry. Among these proteins, we focused on hemopexin as a potential biomarker. The levels of hemopexin in the plasma increased as the silica particle size decreased. In addition, the production of hemopexin depended on the characteristics of the nanomaterials. These results suggested that hemopexin could be an additional biomarker for analyzing the biological responses associated with exposure to silica nanoparticles. We believe that this study will contribute to the development of biomarkers to ensure the safety of silica nanoparticles.

  2. Interference of silica nanoparticles with the traditional Limulus amebocyte lysate gel clot assay.

    PubMed

    Kucki, Melanie; Cavelius, Christian; Kraegeloh, Annette

    2014-04-01

    Endotoxin contaminations of engineered nanomaterials can be responsible for observed biological responses, especially for misleading results in in vitro test systems, as well as in vivo studies. Therefore, endotoxin testing of nanomaterials is necessary to benchmark their influence on cells. Here, we tested the traditional Limulus amebocyte lysate gel clot assay for the detection of endotoxins in nanoparticle suspensions with a focus on possible interference of the particles with the test system. We systematically investigated the effects of nanomaterials made of, or covered by, the same material. Different types of bare or PEGylated silica nanoparticles, as well as iron oxide-silica core shell nanoparticles, were tested. Detailed inhibition/enhancement controls revealed enhanced activity in the Limulus coagulation cascade for all particles with bare silica surface. In comparison, PEGylation led to a lower degree of enhancement. These results indicate that the protein-particle interactions are the basis for the observed inhibition and enhancement effects. The enhancement activity of a particle type was positively related to the calculated particle surface area. For most silica particles tested, a dilution of the sample within the maximum valid dilution was sufficient to overcome non-valid enhancement, enabling semi-quantification of the endotoxin contamination. PMID:23884096

  3. Synthesis of silica nanoparticles from Vietnamese rice husk by sol-gel method

    NASA Astrophysics Data System (ADS)

    Le, Van Hai; Thuc, Chi Nhan Ha; Thuc, Huy Ha

    2013-02-01

    Silica powder at nanoscale was obtained by heat treatment of Vietnamese rice husk following the sol-gel method. The rice husk ash (RHA) is synthesized using rice husk which was thermally treated at optimal condition at 600°C for 4 h. The silica from RHA was extracted using sodium hydroxide solution to produce a sodium silicate solution and then precipitated by adding H2SO4 at pH = 4 in the mixture of water/butanol with cationic presence. In order to identify the optimal condition for producing the homogenous silica nanoparticles, the effects of surfactant surface coverage, aging temperature, and aging time were investigated. By analysis of X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, the silica product obtained was amorphous and the uniformity of the nanosized sample was observed at an average size of 3 nm, and the BET result showed that the highest specific surface of the sample was about 340 m2/g. The results obtained in the mentioned method prove that the rice husk from agricultural wastes can be used for the production of silica nanoparticles.

  4. Synthesis of silica nanoparticles from Vietnamese rice husk by sol–gel method

    PubMed Central

    2013-01-01

    Silica powder at nanoscale was obtained by heat treatment of Vietnamese rice husk following the sol–gel method. The rice husk ash (RHA) is synthesized using rice husk which was thermally treated at optimal condition at 600°C for 4 h. The silica from RHA was extracted using sodium hydroxide solution to produce a sodium silicate solution and then precipitated by adding H2SO4 at pH = 4 in the mixture of water/butanol with cationic presence. In order to identify the optimal condition for producing the homogenous silica nanoparticles, the effects of surfactant surface coverage, aging temperature, and aging time were investigated. By analysis of X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, the silica product obtained was amorphous and the uniformity of the nanosized sample was observed at an average size of 3 nm, and the BET result showed that the highest specific surface of the sample was about 340 m2/g. The results obtained in the mentioned method prove that the rice husk from agricultural wastes can be used for the production of silica nanoparticles. PMID:23388152

  5. Synthesis of silica nanoparticles from Vietnamese rice husk by sol-gel method.

    PubMed

    Le, Van Hai; Thuc, Chi Nhan Ha; Thuc, Huy Ha

    2013-01-01

    Silica powder at nanoscale was obtained by heat treatment of Vietnamese rice husk following the sol-gel method. The rice husk ash (RHA) is synthesized using rice husk which was thermally treated at optimal condition at 600°C for 4 h. The silica from RHA was extracted using sodium hydroxide solution to produce a sodium silicate solution and then precipitated by adding H2SO4 at pH = 4 in the mixture of water/butanol with cationic presence. In order to identify the optimal condition for producing the homogenous silica nanoparticles, the effects of surfactant surface coverage, aging temperature, and aging time were investigated. By analysis of X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, the silica product obtained was amorphous and the uniformity of the nanosized sample was observed at an average size of 3 nm, and the BET result showed that the highest specific surface of the sample was about 340 m2/g. The results obtained in the mentioned method prove that the rice husk from agricultural wastes can be used for the production of silica nanoparticles. PMID:23388152

  6. Gold Nanoparticle Coated Silica Nanorods for Sensitive Visual Detection of microRNA on a Lateral Flow Strip Biosensor.

    PubMed

    Takalkar, Sunitha; Xu, Hui; Chen, Jiao; Baryeh, Kwaku; Qiu, Wanwei; Zhao, Julia X; Liu, And Guodong

    2016-01-01

    We present a rapid and highly sensitive approach for visual detection of microRNA (miRNA) using a gold nanoparticles coated silica nanorod label and lateral flow strip biosensor. Gold nanoparticles were decorated on the silica nanorod surface by a seeding and growth procedure. A single strand DNA probe was immobilized on the gold nanoparticles-silica nanorod surface by a self-assembling process, and the formed DNA-gold nanoparticles-silica nanorod conjugate was used to construct the lateral flow nucleic acid biosensor for detecting miRNA. The captured gold nanoparticles-silica nanorods by sandwich-type hybridization reactions (DNA-RNA-DNA) on the test zone of the lateral flow nucleic acid biosensor produced the characteristic color bands, enabling visual detection of miRNA. After systematic optimization, the new lateral flow nucleic acid biosensor was capable of detecting 10 pM of the miRNA target without instrumentation, which is six times lower than that obtained with the gold nanoparticle-based lateral flow nucleic acid biosensor. The gold nanoparticles coated silica nanorod thus provides a new and sensitive nanolabel for visual detection of biological molecules on the lateral flow biosensor. PMID:27302581

  7. Sensitive electrochemical immunoassay for 2,4,6-trinitrotoluene based on functionalized silica nanoparticle labels

    SciTech Connect

    Wang, Jun; Liu, Guodong; Wu, Hong; Lin, Yuehe

    2008-03-03

    We present a poly(guanine)-functionalized silica nanoparticle (NP) label-based electrochemical immunoassay for sensitively detecting 2,4,6-trinitrotoluene (TNT). This immunoassay takes advantage of magnetic bead–based platform for competitive displacement immunoreactions and separation, and use electroactive nanoparticles as labels for signal amplification. For this assay, anti-TNT-coated magnetic beads interacted with TNT analog-conjugated poly(guanine)-silica NPs and formed analog-anti-TNT immunocomplexes on magnetic beads. The immunocomplexes coated magnetic beads were exposed to TNT samples, which resulted in displacing the analog conjugated poly(guanine) silica NPs into solution by TNT. In contrast, there are no guanine residues releasing into the solution in the absence of TNT. The reaction solution was then separated from the magnetic beads and transferred to the electrode surface for electrochemical measurements of guanine oxidation with Ru(bpy)32+ as mediator. The sensitivity of this TNT assay was greatly enhanced through dual signal amplifications: 1) a large amount of guanine residues on silica nanoparticles is introduced into the test solution by displacement immunoreactions and 2) a Ru(bpy)32+-induced guanine catalytic oxidation further enhances the electrochemical signal. Some experimental parameters for the nanoparticle label-based electrochemical immunoassay were studied and the performance of this assay was evaluated. The method is found to be very sensitive and the detection limit of this assay is ~ 0.1 ng mL-1 TNT. The electrochemical immunoassay based on the poly[guanine]-functionalized silica NP label offers a new approach for sensitive detection of explosives.

  8. Precise quantification of silica and ceria nanoparticle uptake revealed by 3D fluorescence microscopy

    PubMed Central

    Torrano, Adriano A

    2014-01-01

    Summary Particle_in_Cell-3D is a powerful method to quantify the cellular uptake of nanoparticles. It combines the advantages of confocal fluorescence microscopy with fast and precise semi-automatic image analysis. In this work we present how this method was applied to investigate the impact of 310 nm silica nanoparticles on human vascular endothelial cells (HUVEC) in comparison to a cancer cell line derived from the cervix carcinoma (HeLa). The absolute number of intracellular silica nanoparticles within the first 24 h was determined and shown to be cell type-dependent. As a second case study, Particle_in_Cell-3D was used to assess the uptake kinetics of 8 nm and 30 nm ceria nanoparticles interacting with human microvascular endothelial cells (HMEC-1). These small nanoparticles formed agglomerates in biological medium, and the particles that were in effective contact with cells had a mean diameter of 417 nm and 316 nm, respectively. A significant particle size-dependent effect was observed after 48 h of interaction, and the number of intracellular particles was more than four times larger for the 316 nm agglomerates. Interestingly, our results show that for both particle sizes there is a maximum dose of intracellular nanoparticles at about 24 h. One of the causes for such an interesting and unusual uptake behavior could be cell division. PMID:25383274

  9. Multivalent linkers for improved covalent binding of oligonucleotides to dye-doped silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Kelleher, S. M.; Nooney, R. I.; Flynn, S. P.; Clancy, E.; Burke, M.; Daly, S.; Smith, T. J.; Daniels, S.; McDonagh, C.

    2015-09-01

    This paper describes the fabrication of oligonucleotide-coated Cy5-doped silica nanoparticles using a combination of multivalent linkers and their use in surface-based DNA sandwich hybridization assays. Dipodal silane is introduced as a means to fabricate amine-coated silica nanoparticles and its advantages compared to monopodal silanes are discussed. The use of dipodal silane in conjunction with three different polymer linkers (oxidized dextran, linear and 8-arm polyethylene glycol (PEG)) to immobilize single-stranded DNA to Cy5-doped nanoparticles is investigated and dynamic light scattering measurements and Fourier transform infrared spectroscopy are used to follow the progression of the functionalization of the nanoparticles. We observe a significant improvement in the binding stability of the single-stranded DNA when the dipodal silane and 8-arm PEG are used in combination, when compared to alternative conjugation strategies. Both 8mer and 22mer oligonucleotides are securely conjugated to the high-brightness nanoparticles and their availability to hybridize with a complementary strand is confirmed using solution-based DNA hybridization experiments. In addition, a full surface-based sandwich assay demonstrates the potential these nanoparticles have in the detection of less than 500 femtomolar of a DNA analogue of micro RNA, miR-451.

  10. Multivalent linkers for improved covalent binding of oligonucleotides to dye-doped silica nanoparticles.

    PubMed

    Kelleher, S M; Nooney, R I; Flynn, S P; Clancy, E; Burke, M; Daly, S; Smith, T J; Daniels, S; McDonagh, C

    2015-09-11

    This paper describes the fabrication of oligonucleotide-coated Cy5-doped silica nanoparticles using a combination of multivalent linkers and their use in surface-based DNA sandwich hybridization assays. Dipodal silane is introduced as a means to fabricate amine-coated silica nanoparticles and its advantages compared to monopodal silanes are discussed. The use of dipodal silane in conjunction with three different polymer linkers (oxidized dextran, linear and 8-arm polyethylene glycol (PEG)) to immobilize single-stranded DNA to Cy5-doped nanoparticles is investigated and dynamic light scattering measurements and Fourier transform infrared spectroscopy are used to follow the progression of the functionalization of the nanoparticles. We observe a significant improvement in the binding stability of the single-stranded DNA when the dipodal silane and 8-arm PEG are used in combination, when compared to alternative conjugation strategies. Both 8mer and 22mer oligonucleotides are securely conjugated to the high-brightness nanoparticles and their availability to hybridize with a complementary strand is confirmed using solution-based DNA hybridization experiments. In addition, a full surface-based sandwich assay demonstrates the potential these nanoparticles have in the detection of less than 500 femtomolar of a DNA analogue of micro RNA, miR-451. PMID:26294441

  11. Tetracycline-Containing MCM-41 Mesoporous Silica Nanoparticles for the Treatment of Escherichia coli.

    PubMed

    Koneru, Bhuvaneswari; Shi, Yi; Wang, Yu-Chieh; Chavala, Sai H; Miller, Michael L; Holbert, Brittany; Conson, Maricar; Ni, Aiguo; Di Pasqua, Anthony J

    2015-01-01

    Tetracycline (TC) is a well-known broad spectrum antibiotic, which is effective against many Gram positive and Gram negative bacteria. Controlled release nanoparticle formulations of TC have been reported, and could be beneficial for application in the treatment of periodontitis and dental bone infections. Furthermore, TC-controlled transcriptional regulation systems (Tet-on and Tet-off) are useful for controlling transgene expression in vitro and in vivo for biomedical research purposes; controlled TC release systems could be useful here, as well. Mesoporous silica nanomaterials (MSNs) are widely studied for drug delivery applications; Mobile crystalline material 41 (MCM-41), a type of MSN, has a mesoporous structure with pores forming channels in a hexagonal fashion. We prepared 41 ± 4 and 406 ± 55 nm MCM-41 mesoporous silica nanoparticles and loaded TC for controlled dug release; TC content in the TC-MCM-41 nanoparticles was 18.7% and 17.7% w/w, respectively. Release of TC from TC-MCM-41 nanoparticles was then measured in phosphate-buffered saline (PBS), pH 7.2, at 37 °C over a period of 5 h. Most antibiotic was released from both over this observation period; however, the majority of TC was released over the first hour. Efficacy of the TC-MCM-41 nanoparticles was then shown to be superior to free TC against Escherichia coli (E. coli) in culture over a 24 h period, while blank nanoparticles had no effect. PMID:26528964

  12. Thermally Stable Nanocatalyst for High Temperature Reactions: Pt-Mesoporous Silica Core-Shell Nanoparticles

    SciTech Connect

    Joo, Sang Hoon; Park, J.Y.; Tsung, C.-K.; Yamada, Y.; Yang, P.; Somorjai, G.A.

    2008-10-25

    Recent advances in colloidal synthesis enabled the precise control of size, shape and composition of catalytic metal nanoparticles, allowing their use as model catalysts for systematic investigations of the atomic-scale properties affecting catalytic activity and selectivity. The organic capping agents stabilizing colloidal nanoparticles, however, often limit their application in high-temperature catalytic reactions. Here we report the design of a high-temperature stable model catalytic system that consists of Pt metal core coated with a mesoporous silica shell (Pt{at}mSiO{sub 2}). While inorganic silica shells encaged the Pt cores up to 750 C in air, the mesopores directly accessible to Pt cores made the Pt{at}mSiO{sub 2} nanoparticles as catalytically active as bare Pt metal for ethylene hydrogenation and CO oxidation. The high thermal stability of Pt{at}mSiO{sub 2} nanoparticles permitted high-temperature CO oxidation studies, including ignition behavior, which was not possible for bare Pt nanoparticles because of their deformation or aggregation. The results suggest that the Pt{at}mSiO{sub 2} nanoparticles are excellent nanocatalytic systems for high-temperature catalytic reactions or surface chemical processes, and the design concept employed in the Pt{at}mSiO{sub 2} core-shell catalyst can be extended to other metal-metal oxide compositions.

  13. Magnetic properties of magnetite nanoparticles coated with mesoporous silica by sonochemical method

    SciTech Connect

    Ursachi, Irina; Vasile, Aurelia; Chiriac, Horia; Postolache, Petronel; Stancu, Alexandru

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer MCM-41-coating of magnetite nanoparticles performed under ultrasonic irradiation. Black-Right-Pointing-Pointer Ultrasonic irradiation accelerates the formation of the MCM-41 framework. Black-Right-Pointing-Pointer The hysteretic response to an applied field was investigated applying FORC diagram. Black-Right-Pointing-Pointer The average coercive field of the Fe{sub 3}O{sub 4} nanoparticles increased after coating. -- Abstract: In this paper we present the magnetic properties of mesoporous silica-coated Fe{sub 3}O{sub 4} nanoparticles. The coating of magnetite nanoparticles with mesoporous silica shell was performed under ultrasonic irradiation. The obtained mesoporous silica-coated magnetite nanoparticles were characterized by powder X-ray diffraction, focused ion beam-scanning electron microscopy, nitrogen adsorption-desorption isotherms and vibrating sample magnetometer. The hysteretic behavior was studied using first-order reversal curves diagrams. The X-ray diffraction result indicates that the extreme chemical and physical conditions created by acoustic cavitations have an insignificant effect on crystallographic structural characteristic of magnetite nanoparticles. Changes in the coercivity distributions of the magnetite nanoparticles were observed on the first-order reversal curves diagrams for the samples with coated particles compared with the samples containing uncoated particles of magnetite. The coated particles show an increased most probable coercivity of about 20% compared with the uncoated particles which can be associated with an increased anisotropy due to coating even if the interaction field distribution measured on the diagrams are virtually identical for coated/uncoated samples.

  14. Enzyme-controlled sensing-actuating nanomachine based on Janus Au-mesoporous silica nanoparticles.

    PubMed

    Villalonga, Reynaldo; Díez, Paula; Sánchez, Alfredo; Aznar, Elena; Martínez-Máñez, Ramón; Pingarrón, José M

    2013-06-10

    Novel Janus nanoparticles with Au and mesoporous silica faces on opposite sides were prepared using a Pickering emulsion template with paraffin wax as the oil phase. These anisotropic colloids were employed as integrated sensing-actuating nanomachines for enzyme-controlled stimuli-responsive cargo delivery. As a proof of concept, we demonstrated the successful use of the Janus colloids for controlled delivery of tris(2,2'-bipyridyl) ruthenium(II) chloride from the mesoporous silica face, which was grafted with pH-sensitive gatelike scaffoldings. The release was mediated by the on-demand catalytic decomposition of urea by urease, which was covalently immobilized on the Au face. PMID:23649789

  15. Experimental and analytical study of ionic self-assembly of silica and titania nanoparticles

    NASA Astrophysics Data System (ADS)

    Simpson, Brian; Banks, Will; Kim, Vincent; Seredinski, Andrew; Wilson, Katy; Mazilu, Irina; Mazilu, Dan

    2013-03-01

    Using the ionically self-assembled monolayers (ISAM) technique we investigate the time dependence of the surface coverage of thin films that consist of alternating layers of silica or titania nanoparticles deposited on polymer substrates. We conduct experiments in order to investigate the significant observable factors that affected the quality of the coatings including the dipping time, pH, and the molarity of the silica, titania, and PDDA solutions. Using SEM micrographs, we analyzed the surface coverage and compared it to analytical results obtained using a cooperative sequential adsorption model.

  16. Synthesis and characterization of ultra-small superparamagnetic iron oxide nanoparticles thinly coated with silica

    NASA Astrophysics Data System (ADS)

    Bumb, A.; Brechbiel, M. W.; Choyke, P. L.; Fugger, L.; Eggeman, A.; Prabhakaran, D.; Hutchinson, J.; Dobson, P. J.

    2008-08-01

    Ultra-small superparamagnetic iron oxide nanoparticles were synthesized by co-precipitation of iron chloride salts with ammonia and then encapsulated with thin (~2 nm) layers of silica. The particles have been characterized for size, diffraction pattern, surface charge, and magnetic properties. This rapid and economical synthesis has a number of industrial applications; however, the silica-coated particles have been optimized for use in medical applications such as magnetic resonance contrast agents and biosensors, and in DNA capturing, bioseparation and enzyme immobilization.

  17. Silica nanoparticles as a delivery system for nucleic acid-based reagents

    PubMed Central

    Hom, Christopher; Lu, Jie

    2010-01-01

    The transport of nucleic acid-based reagents is predicated upon developing structurally stable delivery systems that can preferentially bind and protect DNA and RNA, and release their cargo upon reaching their designated sites. Recent advancements in tailoring the size, shape, and external surface functionalization of silica materials have led to increased biocompatibility and efficiency of delivery. In this Feature Article, we highlight recent research progress in the use of silica nanoparticles as a delivery vehicle for nucleic acid-based reagents. PMID:20740060

  18. Preparation of fluorescent mesoporous hollow silica-fullerene nanoparticles via selective etching for combined chemotherapy and photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Yang, Yannan; Yu, Meihua; Song, Hao; Wang, Yue; Yu, Chengzhong

    2015-07-01

    Well-dispersed mesoporous hollow silica-fullerene nanoparticles with particle sizes of ~50 nm have been successfully prepared by incorporating fullerene molecules into the silica framework followed by a selective etching method. The fabricated fluorescent silica-fullerene composite with high porosity demonstrates excellent performance in combined chemo/photodynamic therapy.Well-dispersed mesoporous hollow silica-fullerene nanoparticles with particle sizes of ~50 nm have been successfully prepared by incorporating fullerene molecules into the silica framework followed by a selective etching method. The fabricated fluorescent silica-fullerene composite with high porosity demonstrates excellent performance in combined chemo/photodynamic therapy. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02769a

  19. Enhanced hydrophobicity of polyurethane via non-solvent induced surface aggregation of silica nanoparticles.

    PubMed

    Seyfi, Javad; Hejazi, Iman; Jafari, Seyed Hassan; Khonakdar, Hossein Ali; Simon, Frank

    2016-09-15

    Fabrication of superhydrophobic surfaces from hydrophilic polymers has always been regarded as a challenge. In this study, to achieve superhydrophobic polyurethane (PU) surfaces, silica nanoparticles and ethanol as non-solvent were simultaneously utilized during a solution casting-based process. Such modified version of phase separation process was found to be highly efficient, and also it required much lower concentration of nanoparticles to achieve superhydrophobicity as compared to the previously reported methods in the literature. According to the proposed mechanism, non-solvent induces a more profound aggregation of silica nanoparticles at the surface's top layer causing the surface energy to be highly diminished, and thus, the water repellency is improved. Morphology and topography results showed that a unique "triple-sized" structure was formed on the surface of superhydrophobic samples. X-ray photoelectron spectroscopy results proved that both PU macromolecules and silica nanoparticles were concurrently present at the surface layer of the superhydrophobic sample. It was concluded that surface composition and roughness could be regarded as competing factors in achieving superhydrophobicity. Based on the obtained results, the proposed method exhibits a promising potential in large-scale fabrication of surface layers with superhydrophobic property. Moreover, a mechanism was also presented to further explicate the physics behind the suggested method. PMID:27288577

  20. Embedded silica nanoparticles in poly(caprolactone) nanofibrous scaffolds enhanced osteogenic potential for bone tissue engineering.

    PubMed

    Ganesh, Nitya; Jayakumar, Rangasamy; Koyakutty, Manzoor; Mony, Ullas; Nair, Shantikumar V

    2012-09-01

    Poly(caprolactone) (PCL) has been frequently considered for bone tissue engineering because of its excellent biocompatibility. A drawback, however, of PCL is its inadequate mechanical strength for bone tissue engineering and its inadequate bioactivity to promote bone tissue regeneration from mesenchymal stem cells. To correct this deficiency, this work investigates the addition of nanoparticles of silica (nSiO(2)) to the scaffold to take advantage of the known bioactivity of silica as an osteogenic material and also to improve the mechanical properties through nanoscale reinforcement of the PCL fibers. The nanocomposite scaffolds and the pristine PCL scaffolds were evaluated physicochemically, mechanically, and biologically in the presence of human mesenchymal stem cells (hMSCs). The results indicated that, when the nanoparticles of size approximately 10 nm (concentrations of 0.5% and 1% w/v) were embedded within, or attached to, the PCL nanofibers, there was a substantial increase in scaffold strength, protein adsorption, and osteogenic differentiation of hMSCs. These nSiO(2) nanoparticles, when directly added to the cells evidently pointed to ingestion of these particles by the cells followed by cell death. The polymer nanofibers appeared to protect the cells by preventing ingestion of the silica nanoparticles, while at the same time adequately exposing them on fiber surfaces for their desired bioactivity. PMID:22725098

  1. Immune response to functionalized mesoporous silica nanoparticles for targeted drug delivery.

    PubMed

    Heidegger, Simon; Gössl, Dorothée; Schmidt, Alexandra; Niedermayer, Stefan; Argyo, Christian; Endres, Stefan; Bein, Thomas; Bourquin, Carole

    2016-01-14

    Multifunctional mesoporous silica nanoparticles (MSN) have attracted substantial attention with regard to their high potential for targeted drug delivery. For future clinical applications it is crucial to address safety concerns and understand the potential immunotoxicity of these nanoparticles. In this study, we assess the biocompatibility and functionality of multifunctional MSN in freshly isolated, primary murine immune cells. We show that the functionalized silica nanoparticles are rapidly and efficiently taken up into the endosomal compartment by specialized antigen-presenting cells such as dendritic cells. The silica nanoparticles showed a favorable toxicity profile and did not affect the viability of primary immune cells from the spleen in relevant concentrations. Cargo-free MSN induced only very low immune responses in primary cells as determined by surface expression of activation markers and release of pro-inflammatory cytokines such as Interleukin-6, -12 and -1β. In contrast, when surface-functionalized MSN with a pH-responsive polymer capping were loaded with an immune-activating drug, the synthetic Toll-like receptor 7 agonist R848, a strong immune response was provoked. We thus demonstrate that MSN represent an efficient drug delivery vehicle to primary immune cells that is both non-toxic and non-inflammagenic, which is a prerequisite for the use of these particles in biomedical applications. PMID:26659601

  2. Synthesis, characterization, and biodistribution studies of (99m)Tc-labeled SBA-16 mesoporous silica nanoparticles.

    PubMed

    de Barros, André Luís Branco; de Oliveira Ferraz, Karina Silva; Dantas, Thais Cristina Soares; Andrade, Gracielle Ferreira; Cardoso, Valbert Nascimento; Sousa, Edésia Martins Barros de

    2015-11-01

    Along with anti-cancer drug delivery researches, many efforts have been done to develop new tracers for diagnostic applications. Based on advances in molecular imaging, nanoparticles can be used to visualize, characterize and measure biological process at molecular and cellular level. Therefore, the purpose of this study was to synthesize, characterize and radiolabeled mesoporous silica nanoparticles (MSNs) for in vivo applications. The nanoparticles were synthesized, functionalized with 3-aminopropyltriethoxysilane (APTES) and then, anchored with diethylenetriaminepentaacetic acid (DTPA). Particles were physicochemical characterized by elemental analysis (CHN), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and zeta potential, and were morphologically characterized by scanning electron microscopy (SEM), low-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. Results indicate that functionalization process was successfully achieved. Next, functionalized silica nanoparticles were radiolabeled with technetium-99m showing high radiochemical yields and high radiolabeled stability. These findings allow the use of the particles for in vivo applications. Biodistribution and scintigraphic images were carried out in healthy mice in order to determine the fate of the particles. Results from in vivo experiments showed high uptake by liver, as expected due to phagocytosis. However, particles also showed a significant uptake in the lungs, indicated by high lung-to-non-target tissue ratio. In summary, taking into account the great potential of these silica mesoporous structures to carry molecules this platform could be a good strategy for theranostic purposes. PMID:26249579

  3. Aggregation-Induced Emission Luminogen-Embedded Silica Nanoparticles Containing DNA Aptamers for Targeted Cell Imaging.

    PubMed

    Wang, Xiaoyan; Song, Panshu; Peng, Lu; Tong, Aijun; Xiang, Yu

    2016-01-13

    Conventional fluorophores usually undergo aggregation-caused quenching (ACQ), which limits the loading amount of these fluorophores in nanoparticles for bright fluorescence imaging. On the contrary, fluorophores with aggregation-induced emission (AIE) characteristics are strongly fluorescent in their aggregate states and have been an ideal platform for developing highly fluorescent nanomaterials, such as fluorescent silica nanoparticles (FSNPs). In this work, AIE luminogens based on salicylaldehyde hydrazones were embedded in silica nanoparticles through a facile noncovalent approach, which afforded AIE-FSNPs emitting much brighter fluorescence than that of some commercial fluorescein-doped silica and polystyrene nanoparticles. These AIE-FSNPs displaying multiple fluorescence colors were fabricated by a general method, and they underwent much less fluorescence variation due to environmental pH changes compared with fluorescein-hybridized FSNPs. In addition, a DNA aptamer specific to nucleolin was functionalized on the surface of AIE-FSNPs for targeted cell imaging. Fluorescent microscopy and flow cytometry studies both revealed highly selective fluorescence staining of MCF-7 (a cancer cell line with nucleolin overexpression) over MCF-10A (normal) cells by the aptamer-functionalized AIE-FSNPs. The fluorescence imaging in different color channels was achieved using AIE-FSNPs containing each of the AIE luminogens, as well as photoactivatable fluorescent imaging of target cells by the caged AIE fluorophore. PMID:26653325

  4. Development of silica-coated silver iodide nanoparticles and their biodistribution.

    PubMed

    Sakurai, Yu; Tada, Hiroshi; Gonda, Kohsuke; Takeda, Motohiro; Cong, Liman; Amari, Masakazu; Kobayashi, Yoshio; Watanabe, Mika; Ishida, Takanori; Ohuchi, Noriaki

    2012-01-01

    Nanomaterials have great potential in the field of medicine and have been studied extensively. In a previous study, we addressed the potential of silver iodide (AgI) as X-ray contrast media, because it possessed high imaging ability in the measurement by X-ray computed tomography (X-CT) in vitro, and its surface can be modified with many functional groups. We developed the method of silica coating to make AgI nanoparticles more stable and uniform in size. However, the safety and metabolism of nanoparticles in vivo remains to be determined. The objective of the present study was to evaluate the in vivo biodistribution of silica-coated AgI nanoparticles (SAgINPs). X-CT, transmission electron microscopy (TEM), and inductively coupled plasma atomic emission spectrometry (ICP-AES) were performed prior to and at intervals following the intravenous administration of SAgINPs to rats and rabbits. ICP-AES is a spectral technique that can determine the presence and concentrations of metal samples. The X-CT study showed long-period enhancement in the liver and spleen, but not in the bladder of rats. The TEM study demonstrated that SAgINPs were found in hepatocytes. Using ICP-AES, Ag was detected in the bile juice of rabbits, but not found in the urine of these animals, suggesting that SAgINPs are excreted via the liver. This study shows the quantitative biodistribution of silica-coated nanoparticles for the first time, indicating that our silica coating technique is useful for development of nanoparticles with hepatic excretion. In conclusion, the SAgINPs may provide X-ray contrast media with high imaging ability and biocompatibility. PMID:23132228

  5. Biological Applications and Transmission Electron Microscopy Investigations of Mesoporous Silica Nanoparticles

    SciTech Connect

    Brian G. Trewyn

    2006-05-01

    The research presented and discussed within involves the development of novel biological applications of mesoporous silica nanoparticles (MSN) and an investigation of mesoporous material by transmission electron microscopy (TEM). Mesoporous silica nanoparticles organically functionalized shown to undergo endocytosis in cancer cells and drug release from the pores was controlled intracellularly and intercellularly. Transmission electron microscopy investigations demonstrated the variety of morphologies produced in this field of mesoporous silica nanomaterial synthesis. A series of room-temperature ionic liquid (RTIL) containing mesoporous silica nanoparticle (MSN) materials with various particle morphologies, including spheres, ellipsoids, rods, and tubes, were synthesized. By changing the RTIL template, the pore morphology was tuned from the MCM-41 type of hexagonal mesopores to rotational moire type of helical channels, and to wormhole-like porous structures. These materials were used as controlled release delivery nanodevices to deliver antibacterial ionic liquids against Escherichia coli K12. The involvement of a specific organosiloxane function group, covalently attached to the exterior of fluorescein doped mesoporous silica nanoparticles (FITC-MSN), on the degree and kinetics of endocytosis in cancer and plant cells was investigated. The kinetics of endocystosis of TEG coated FITC-MSN is significantly quicker than FITC-MSN as determined by flow cytometry experiments. The fluorescence confocal microscopy investigation showed the endocytosis of TEG coated-FITC MSN triethylene glycol grafted fluorescein doped MSN (TEG coated-FITC MSN) into both KeLa cells and Tobacco root protoplasts. Once the synthesis of a controlled-release delivery system based on MCM-41-type mesoporous silica nanorods capped by disulfide bonds with superparamagnetic iron oxide nanoparticles was completed. The material was characterized by general methods and the dosage and kinetics of the

  6. Amine modification of nonporous silica nanoparticles reduces inflammatory response following intratracheal instillation in murine lungs.

    PubMed

    Morris, Angie S; Adamcakova-Dodd, Andrea; Lehman, Sean E; Wongrakpanich, Amaraporn; Thorne, Peter S; Larsen, Sarah C; Salem, Aliasger K

    2016-01-22

    Amorphous silica nanoparticles (NPs) possess unique material properties that make them ideal for many different applications. However, the impact of these materials on human and environmental health needs to be established. We investigated nonporous silica NPs both bare and modified with amine functional groups (3-aminopropyltriethoxysilane (APTES)) in order to evaluate the effect of surface chemistry on biocompatibility. In vitro data showed there to be little to no cytotoxicity in a human lung cancer epithelial cell line (A549) for bare silica NPs and amine-functionalized NPs using doses based on both mass concentration (below 200μg/mL) and exposed total surface area (below 14m(2)/L). To assess lung inflammation, C57BL/6 mice were administered bare or amine-functionalized silica NPs via intra-tracheal instillation. Two doses (0.1 and 0.5mg NPs/mouse) were tested using the in vivo model. At the higher dose used, bare silica NPs elicited a significantly higher inflammatory response, as evidence by increased neutrophils and total protein in bronchoalveolar lavage (BAL) fluid compared to amine-functionalized NPs. From this study, we conclude that functionalization of nonporous silica NPs with APTES molecules reduces murine lung inflammation and improves the overall biocompatibility of the nanomaterial. PMID:26562768

  7. Gold and silica-coated gold nanoparticles as thermographic labels for DNA detection.

    PubMed

    Cerruti, Marta G; Sauthier, Marc; Leonard, Donovan; Liu, Dage; Duscher, Gerard; Feldheim, Daniel L; Franzen, Stefan

    2006-05-15

    The infrared emissivity of Au and silica-coated Au nanoparticles (Au NPs) deposited on indium tin oxide substrates was investigated. NPs were irradiated with laser light at a frequency close to the Au plasmon resonance band, and the blackbody radiation emitted as a result was monitored with an IR camera equipped with an InAs array detector. The differences in temperature before and after laser irradiation were recorded (T-jumps) and were found to be directly proportional to the number of particles present on the slide and to the laser power used in the experiment. Coating Au NPs with silica increased the measured T-jumps 2-5 times, depending on the thickness of the silica shell. This was in agreement with the observation that silica has a much higher IR emissivity than Au. Both Au and silica-coated Au NPs were then tested as labels for thermographic DNA detection. Target DNA concentrations as low as 100 pM were recorded when Au NPs were used as labels and as low as 10 pM when silica-coated Au NPs were used. PMID:16689528

  8. Silica Nanoparticles Target a Wnt Signal Transducer for Degradation and Impair Embryonic Development in Zebrafish.

    PubMed

    Yi, Hongyang; Wang, Zhuyao; Li, Xiaojiao; Yin, Min; Wang, Lihua; Aldalbahi, Ali; El-Sayed, Nahed Nasser; Wang, Hui; Chen, Nan; Fan, Chunhai; Song, Haiyun

    2016-01-01

    Many types of biocompatible nanomaterials have proven of low cytotoxicity and hold great promise for various applications in nanomedicine. Whereas they generally do not cause apparent organ toxicity or tissue damage in adult animals, it is yet to determine their biological consequences in more general contexts. In this study, we investigate how silica nanoparticles (NPs) affect cellular activities and functions under several physiological or pathological conditions. Although silica NPs are generally regarded as "inert" nanocarriers and widely employed in biomedical studies, we find that they actively affect Wnt signaling in various types of cell lines, diminishing its anti-adipogenic effect in preadipocytes and pro-invasive effect in breast cancer cells, and more significantly, impair Wnt-regulated embryonic development in Zebrafish. We further demonstrate that intracellular silica NPs block Wnt signal transduction in a way resembling signaling molecules. Specifically, silica NPs target the Dvl protein, a key component of Wnt signaling cascade, for lysosomal degradation. As Wnt signaling play significant roles in embryonic development and adipogenesis, the observed physiological effects beyond toxicity imply potential risk of obesity, or developmental defects in somitogenesis and osteogenesis upon exposure to silica NPs. In addition, given the clinical implications of Wnt signaling in tumorigenesis and cancer metastasis, our work also establishes for the first time a molecular link between nanomaterials and the Wnt signaling pathway, which opens new door for novel applications of unmodified silica NPs in targeted therapy for cancers and other critical illness. PMID:27570552

  9. Silica-coating as protective shell for the risk management of nanoparticles

    NASA Astrophysics Data System (ADS)

    Gardini, D.; Blosi, M.; Delpivo, C.; Ortelli, S.; Costa, A. L.

    2013-04-01

    Nanoparticles (NPs) surface functionalization with silica (SiO2) has attracted high attention due to hydrophilicity, biocompatibility, chemical and thermal stability of silica. The present work is addressed to the production and characterization of SiO2-coatings on titanium dioxide (TiO2) and silver (Ag) NPs dispersed in aqueous solutions (commercial nanosols) with the aim to manage the potential risk that such NPs could generate in occupational exposure scenarios. A colloidal approach, based on principles of heterocoagulation in which opposite charged NPs are forced to coagulate in hierarchical structures, imposed by their relative size and weight ratio, was followed. The results were compared with a chemical approach, based on nucleation of silica phase from silica precursor solutions on the surfaces of TiO2 or Ag NPs seeds. In order to increase the adhesion of silica on TiO2 and Ag surfaces, heterocoagulated sols were spray-dried and subsequently redispersed in water to check the feasibility of such approach at industrial level. Physicochemical properties such as zeta potential, electrical conductivity, particle-size distribution, specific surface area and morphology of the samples produced with different SiO2:TiO2 and SiO2:Ag weight ratios were collected and compared. Indirect evidences of silica coating were obtained.

  10. A dual role of transient receptor potential melastatin 2 channel in cytotoxicity induced by silica nanoparticles

    PubMed Central

    Yu, Peilin; Li, Jin; Jiang, Jialin; Zhao, Zunquan; Hui, Zhaoyuan; Zhang, Jun; Zheng, Yifan; Ling, Daishun; Wang, Lie; Jiang, Lin-Hua; Luo, Jianhong; Zhu, Xinqiang; Yang, Wei

    2015-01-01

    Silica nanoparticles (NPs) have remarkable applications. However, accumulating evidence suggests NPs can cause cellular toxicity by inducing ROS production and increasing intracellular Ca2+ ([Ca2+]i), but the underlying molecular mechanism is largely unknown. Transient receptor potential melastatin 2 (TRPM2) channel is known to be a cellular redox potential sensor that provides an important pathway for increasing the [Ca2+]i under oxidative stress. In this study, we examined the role of TRPM2 channel in silica NPs-induced oxidative stress and cell death. By quantitation of cell viability, ROS production, [Ca2+]i, and protein identification, we showed that TRPM2 channel is required for ROS production and Ca2+ increase induced by silica NPs through regulating NADPH oxidase activity in HEK293 cells. Strikingly, HEK293 cells expressing low levels of TRPM2 were more susceptible to silica NPs than those expressing high levels of TRPM2. Macrophages from young mice showed significantly lower TRPM2 expression than those from senescent mice and had significantly lower viability after silica NPs exposure than those from senescent ones. Taken together, these findings demonstrate for the first time that TRPM2 channel acts as an oxidative stress sensor that plays a dual role in silica NPs-induced cytotoxicity by differentially regulating the NADPH oxidase activity and ROS generation. PMID:26656285

  11. Silica Nanoparticles Target a Wnt Signal Transducer for Degradation and Impair Embryonic Development in Zebrafish

    PubMed Central

    Yi, Hongyang; Wang, Zhuyao; Li, Xiaojiao; Yin, Min; Wang, Lihua; Aldalbahi, Ali; El-Sayed, Nahed Nasser; Wang, Hui; Chen, Nan; Fan, Chunhai; Song, Haiyun

    2016-01-01

    Many types of biocompatible nanomaterials have proven of low cytotoxicity and hold great promise for various applications in nanomedicine. Whereas they generally do not cause apparent organ toxicity or tissue damage in adult animals, it is yet to determine their biological consequences in more general contexts. In this study, we investigate how silica nanoparticles (NPs) affect cellular activities and functions under several physiological or pathological conditions. Although silica NPs are generally regarded as “inert” nanocarriers and widely employed in biomedical studies, we find that they actively affect Wnt signaling in various types of cell lines, diminishing its anti-adipogenic effect in preadipocytes and pro-invasive effect in breast cancer cells, and more significantly, impair Wnt-regulated embryonic development in Zebrafish. We further demonstrate that intracellular silica NPs block Wnt signal transduction in a way resembling signaling molecules. Specifically, silica NPs target the Dvl protein, a key component of Wnt signaling cascade, for lysosomal degradation. As Wnt signaling play significant roles in embryonic development and adipogenesis, the observed physiological effects beyond toxicity imply potential risk of obesity, or developmental defects in somitogenesis and osteogenesis upon exposure to silica NPs. In addition, given the clinical implications of Wnt signaling in tumorigenesis and cancer metastasis, our work also establishes for the first time a molecular link between nanomaterials and the Wnt signaling pathway, which opens new door for novel applications of unmodified silica NPs in targeted therapy for cancers and other critical illness. PMID:27570552

  12. Charge separation across the silica nanoparticle/water interface

    SciTech Connect

    Dimitrijevic, N.M.; Henglein, A.; Meisel, D.

    1999-08-26

    Aqueous suspensions of silica particles at high concentrations were irradiated with a short pulse of electrons in the presence of scavengers of OH radicals. The scavengers were chosen to minimize their adsorption on the particle surface. It was found that essentially no holes cross the particle/water interface to generate OH radicals. All of the holes that are originally generated by the ionizing radiation in the silica remain in the particle; even at the smallest size used (7-nm diameter). This is contrasted with electrons, which were earlier shown to escape the particles into the water, even at much larger particle sizes. Implications to removal of pollutants and to management of radioactive materials are often cited as motivation for these studies.

  13. Fracture Behavior of Silica- and Rubber-Nanoparticle-Toughed Epoxies

    NASA Astrophysics Data System (ADS)

    Labak, Amelia K.

    Particle-toughened crosslinked epoxies are popular materials for a variety of applications, including the microelectronics industry. For this application, the properties of these materials, such as a high fracture toughness and a low coefficient of thermal expansion, are highly appealing. In order to achieve these properties, inorganic particles are often added into the matrix. For this study, both inorganic and organic particles-toughened epoxies are investigated in the hopes of finding an optimized system. In particular, in this study, micron-sized silica and nano-sized rubbery block copolymers are added to an amine-cured epoxy matrix. A series of rubber-only and silica-only systems are investigated for their contribution to the fracture toughness. Then, a series of hybrid systems are investigated. The hypothesis is that the rubber will contribute toughness through rubber particle cavitation and matrix void growth and the silica will contribute toughness through crack pinning and bridging and particle debonding. In the hybrid systems, these mechanisms will take place at a different scale. Therefore, the nanoscale mechanisms of the rubber will be able to function at the same time as the micron sized mechanisms of the silica and the resultant toughness will be synergistically higher. The results from this study show an interesting contribution from the rubber particles both in the rubber-only systems and the hybrid system. Ultimately, there was a marked increase in the fracture toughness of the hybrid systems, although not synergistic. This increase indicates that it would be possible to create an optimized hybrid system from the combined addition of these particles.

  14. A facile one-pot synthesis of ruthenium hydroxide nanoparticles on magnetic silica: Aqueous hydration of nitriles to amides

    EPA Science Inventory

    One-pot synthesis of ruthenium hydroxide nanoparticles on magnetic silica is described which involve the in situ generation of magnetic silica (Fe3O4@ SiO2) and ruthenium hydroxide immobilization; the hydration of nitriles occurs in high yield and excellent selectivity using this...

  15. Fabrication, Light Emission, and Magnetism of Silica Nanoparticles Hybridized with AIE Luminogens and Inorganic Nanostructures

    NASA Astrophysics Data System (ADS)

    Faisal, Mahtab

    Much research efforts have been devoted in developing new synthetic approaches for fluorescent silica nanoparticles (FSNPs) due to their potential high-technological applications. However, light emissions from most of the FSNPs prepared so far have been rather weak. This is due to the emission quenching caused by the aggregation of fluorophores in the solid state. We have observed a novel phenomenon of aggregation-induced emission (AIE): a series of propeller-shaped molecules such as tetraphenylethene (TPE) and silole are induced to emit efficiently by aggregate formation. Thus, they are ideal fluorophors for the construction of FSNPs and my thesis work focuses on the synthesis of silica nanoparticles containing these luminogens and magnetic nanostructures. Highly emissive FSNPs with core-shell structures are fabricated by surfactant-free sol-gel reactions of tetraphenylethene- (TPE) and silole-functionalized siloxanes followed by the reactions with tetraethoxysilane. The FSNPs are uniformly sized, surface-charged and colloidally stable. The diameters of the FSNPs are tunable in the range of 45--295 nm by changing the reaction conditions. Whereas their TPE and silole precursors are non-emissive, the FSNPs emit strong visible lights, thanks to the novel aggregation-induced emission characteristics of the TPE and silole aggregates in the hybrid nanoparticles. The FSNPs pose no toxicity to living cells and can be utilized to selectively image cytoplasm of HeLa cells. Applying the same tool in the presence of citrate-coated magnetite nanoparticles, uniform magnetic fluorescent silica nanoparticles (MFSNPs) with smooth surfaces are fabricated. These particles exhibit appreciable surface charges and hence good colloidal stability. They are superparamagnetic, exhibiting no hysteresis at room temperature. UV irradiation of a suspension of MFSNPs in ethanol gives strong blue and green emissions. The MFSNPs can selectively stain the cytoplasmic regions of the living cells

  16. Functionalized Silica Nanoparticles As an Alternative Platform for Targeted Drug-Delivery of Water Insoluble Drugs.

    PubMed

    de Oliveira, Luciane França; Bouchmella, Karim; Gonçalves, Kaliandra de Almeida; Bettini, Jefferson; Kobarg, Jörg; Cardoso, Mateus Borba

    2016-04-01

    The selective action of drugs in tumor cells is a major problem in cancer therapy. Most chemotherapy drugs act nonspecifically and damage both cancer and healthy cells causing various side effects. In this study, the preparation of a selective drug delivery system, which is able to act as a carrier for hydrophobic and anticancer drugs is reported. Amino-functionalized silica nanoparticles loaded with curcumin were successfully synthesized via sol-gel approach and duly characterized. Thereafter, the targeting ligand, folate, was covalently attached to amino groups of nanoparticle surface through amide bond formation. The cytotoxic effect of nanoparticles on prostate cancer cells line was evaluated and compared to normal cells line (prostate epithelial cell). Cytotoxicity experiments demonstrated that folate-functionalized nanoparticles were significantly cytotoxic to tumor cells, whereas normal cells were much less affected by the presence of these structures. PMID:26930039

  17. Titanium dioxide encapsulation of supported Ag nanoparticles on the porous silica bead for increased photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Deng, Lu; Sun, Chaochao; Li, Junqi; Zhu, Zhenfeng

    2015-01-01

    A new synthetic strategy has been developed to encapsulate Ag nanoparticles in heterogeneous catalysts to prevent their dropping and sintering. Ag nanoparticles with diameters about 5-10 nm were first supported on the porous silica bead. These were then covered with a fresh layer of titanium dioxide with the thickness about 5 nm. SEM and TEM images were used to confirm the success of each synthesis step, and the photocatalytic activity of the as-synthesized samples was evaluated by photocatalytic decolorization of Rhodamine B (Rh B) aqueous solution at ambient temperature under both UV and visible light irradiation. The resulting titanium dioxide encapsulated Ag nanoparticles exhibited an enhanced photocatalytic activity under both UV and visible light irradiation, this can be attributed to effective charge separation and light harvesting of the plasmonic silver nanoparticles decoration, even the reducing of the exciton recombination rate caused by the small grain size of anatase TiO2 nanocrystals.

  18. Enhancement of Electrochromic Durability of a Film Made of Silica-Polyaniline Core-Shell Nanoparticles

    NASA Astrophysics Data System (ADS)

    Hwang, Taejin; Lee, Heungyeol; Kim, Hohyeong; Kim, Gyuntak; Mun, Gyeongjin

    Enhancing the operation life time or the electrochemical durability is one of the key issues in electrochromic material studies. It is generally accepted that the inorganic-organic hybrid structure is one of the effective ways to enhance the chemical stability of the material. In this study, an electrochromic film made of silica-polyaniline core-shell composite nanoparticles was tested. The composite particles were prepared through a chemical dispersion polymerization of aniline in an aqueous colloidal solution of silica. The synthesized particles were then dispersed into ethanol and the solution was deposited onto an Indium Tin Oxide (ITO)-coated glass substrate. The electrochromic characterization on the prepared films was performed using the cyclovoltammetry and the optical response to a switching potential. The results showed that the inorganic-organic core-shell hybrid nanoparticle could be a promising choice for the enhancement of electrochromic durability.

  19. Core–Shell Bimetallic Nanoparticles Robustly Fixed on the Outermost Surface of Magnetic Silica Microspheres

    PubMed Central

    Park, Hye Hun; Woo, Kyoungja; Ahn, Jae-Pyoung

    2013-01-01

    The major challenges in practically utilising the immense potential benefits of nanomaterials are controlling aggregation, recycling the nanomaterials, and fabricating well-defined nanoparticulate materials using innovative methods. We present a novel innovative synthetic strategy for core–shell bimetallic nanoparticles that are well-defined, ligand-free, and robustly fixed on the outermost surface of recyclable magnetic silica microspheres. The strategy includes seeding, coalescing the seeds to cores, and then growing shells from the cores on aminopropyl-functionalised silica microspheres so that the cores and aminopropyl moieties are robustly embedded in the shell materials. The representative Au–Ag bimetallic nanoparticles fixed on the microsphere showed excellent catalytic performance that remained consistent during repeated catalytic cycles. PMID:23511209

  20. Photophysical studies of newly derivatized mono substituted phthalocyanines grafted onto silica nanoparticles via click chemistry.

    PubMed

    Fashina, Adedayo; Amuhaya, Edith; Nyokong, Tebello

    2015-04-01

    This work reports on the synthesis, characterization and photophysical studies of newly derived phthalocyanine complexes and the phthalocyanine-silica nanoparticles conjugates. The derived phthalocyanine complexes have one terminal alkyne group. The derived phthalocyanine complexes showed improved photophysical properties (ФF, ФT, ΦΔ and τT) compared to the respective phthalocyanine complexes from which they were derived. The derived phthalocyanine complexes were conjugated to the surface of an azide functionalized silica nanoparticles via copper (1) catalyzed cyclo-addition reaction. All the conjugates showed lower triplet quantum yields ranging from 0.37 to 0.44 compared to the free phthalocyanine complexes. The triplet lifetimes ranged from 352 to 484 μs for the conjugates and from 341 to 366 μs for the free phthalocyanine complexes. PMID:25615674

  1. Photophysical studies of newly derivatized mono substituted phthalocyanines grafted onto silica nanoparticles via click chemistry

    NASA Astrophysics Data System (ADS)

    Fashina, Adedayo; Amuhaya, Edith; Nyokong, Tebello

    2015-04-01

    This work reports on the synthesis, characterization and photophysical studies of newly derived phthalocyanine complexes and the phthalocyanine-silica nanoparticles conjugates. The derived phthalocyanine complexes have one terminal alkyne group. The derived phthalocyanine complexes showed improved photophysical properties (ФF, ФT, ΦΔ and τT) compared to the respective phthalocyanine complexes from which they were derived. The derived phthalocyanine complexes were conjugated to the surface of an azide functionalized silica nanoparticles via copper (1) catalyzed cyclo-addition reaction. All the conjugates showed lower triplet quantum yields ranging from 0.37 to 0.44 compared to the free phthalocyanine complexes. The triplet lifetimes ranged from 352 to 484 μs for the conjugates and from 341 to 366 μs for the free phthalocyanine complexes.

  2. Biomedical Applications of Functionalized Hollow Mesoporous Silica Nanoparticles: Focusing on Molecular Imaging

    PubMed Central

    Shi, Sixiang; Chen, Feng; Cai, Weibo

    2013-01-01

    Hollow mesoporous silica nanoparticles (HMSNs), with a large cavity inside each original mesoporous silica nanoparticle (MSN), have recently gained increasing interest due to their tremendous potential for cancer imaging and therapy. The last several years have witnessed a rapid development in engineering of functionalized HMSNs (i.e. f-HMSNs) with various types of inorganic functional nanocrystals integrated into the system for imaging and therapeutic applications. In this review article, we summarize the recent progress in the design and biological applications of f-HMSNs, with a special emphasis on molecular imaging. Commonly used synthetic strategies for the generation of high quality HMSNs will be discussed in detail, followed by a systematic review of engineered f-HMSNs for optical, positron emission tomography, magnetic resonance, and ultrasound imaging in preclinical studies. Lastly, we also discuss the challenges and future research directions regarding the use of f-HMSNs for cancer imaging and therapy. PMID:24279491

  3. Surface functionalization of silica nanoparticles with cysteine: a low-fouling zwitterionic surface.

    PubMed

    Rosen, Joshua E; Gu, Frank X

    2011-09-01

    Herein, we report on the functionalization of silica nanoparticles with a small molecule, the amino acid cysteine, in order to create a low-fouling zwitterionic surface for nanomedicine applications. The cysteine functionalization was shown to impart the particles with excellent stability in both salt and single-protein solutions of lysozyme (positively charged) and bovine serum albumin (negatively charged). Bare silica particles precipitated immediately in a lysozyme solution, while cysteine-functionalized particles were stable for 20 h. Furthermore, the particles displayed excellent long-term stability in solutions of human serum showing no aggregation over a period of 14 days. The functionalized particles also possess multiple reactive surface groups for further coupling reactions. We believe that the surface functionalization schemes described in this report represent a versatile and effective method of stabilizing nanoparticle systems in biological media for their use in a variety of therapeutic and diagnostic applications. PMID:21761888

  4. Influence of Scaffold Size on Bactericidal Activity of Nitric Oxide Releasing Silica Nanoparticles

    PubMed Central

    Carpenter, Alexis W.; Slomberg, Danielle L.; Rao, Kavitha S.; Schoenfisch, Mark H.

    2011-01-01

    A reverse microemulsion synthesis was used to prepare amine functionalized silica nanoparticles of three distinct sizes (i.e., 50, 100, and 200 nm) with identical amine concentrations. The resulting hybrid nanoparticles, consisting of N-(6 aminohexyl) aminopropyltrimethoxysilane and tetraethoxysilane, were highly monodisperse in size. N-diazeniumdiolate nitric oxide (NO) donors were subsequently formed on secondary amines while controlling reaction conditions to keep the total amount of nitric oxide (NO) released constant for each particle size. The bactericidal efficacy of the NO releasing nanoparticles against Pseudomonas aeruginosa increased with decreasing particle size. Additionally, smaller diameter nanoparticles were found to associate with the bacteria at a faster rate and to a greater extent than larger particles. Neither control (non-NO-releasing) nor NO releasing particles exhibited toxicity towards L929 mouse fibroblasts at concentrations above their respective minimum bactericidal concentrations. This study represents the first investigation of the bactericidal efficacy of NO-releasing silica nanoparticles as a function of particle size. PMID:21842899

  5. Chondroitin sulfate functionalized mesostructured silica nanoparticles as biocompatible carriers for drug delivery

    PubMed Central

    Xi, Juqun; Qin, Jin; Fan, Lei

    2012-01-01

    Mesoporous silica nanoparticles (MSNs) have garnered a great deal of attention as potential carriers for therapeutic payloads. Here, we report a pH-responsive drug-carrier based on chondroitin sulfate functionalized mesostructured silica nanoparticles (NMChS-MSNs) ie, the amidation between NMChS macromer and amino group functionalized MSNs. The prepared nanoparticles were characterized using dynamic light scattering, fourier transform infrared spectroscopy and transmission electron microscopy. The resultant NMChS-MSNs were uniform spherical nanoparticles with a mean diameter of approximately 74 nm. Due to the covalent graft of hydrophilic and pH responsive NMChS, the NMChS-MSNs could be well dispersed in aqueous solution, which is favorable to being utilized as drug carriers to construct a pH-responsive controlled drug delivery system. Doxorubicin hydrochloride (DOX), a well-known anticancer drug, could be effectively loaded into the channels of NMChS-MSNs through electrostatic interactions between drug and matrix. The drug release rate of DOX@NMChS-MSNs was pH dependent and increased with the decrease of pH. The in vitro cytotoxicity test indicated that NMChS-MSNs were highly biocompatible and suitable to use as drug carriers. Our results imply that chondroitin sulfate functionalized nanoparticles are promising platforms to construct the pH-responsive controlled drug delivery systems for cancer therapy. PMID:23091377

  6. Colorimetric-based detection of TNT explosives using functionalized silica nanoparticles.

    PubMed

    Idros, Noorhayati; Ho, Man Yi; Pivnenko, Mike; Qasim, Malik M; Xu, Hua; Gu, Zhongze; Chu, Daping

    2015-01-01

    This proof-of-concept study proposes a novel sensing mechanism for selective and label-free detection of 2,4,6-trinitrotoluene (TNT). It is realized by surface chemistry functionalization of silica nanoparticles (NPs) with 3-aminopropyl-triethoxysilane (APTES). The primary amine anchored to the surface of the silica nanoparticles (SiO2-NH2) acts as a capturing probe for TNT target binding to form Meisenheimer amine-TNT complexes. A colorimetric change of the self-assembled (SAM) NP samples from the initial green of a SiO2-NH2 nanoparticle film towards red was observed after successful attachment of TNT, which was confirmed as a result of the increased separation between the nanoparticles. The shift in the peak wavelength of the reflected light normal to the film surface and the associated change of the peak width were measured, and a merit function taking into account their combined effect was proposed for the detection of TNT concentrations from 10-12 to 10-4 molar. The selectivity of our sensing approach is confirmed by using TNT-bound nanoparticles incubated in AptamerX, with 2,4-dinitrotoluene (DNT) and toluene used as control and baseline, respectively. Our results show the repeatable systematic color change with the TNT concentration and the possibility to develop a robust, easy-to-use, and low-cost TNT detection method for performing a sensitive, reliable, and semi-quantitative detection in a wide detection range. PMID:26046595

  7. Encapsulation of FRET-based glucose and maltose biosensors to develop functionalized silica nanoparticles.

    PubMed

    Faccio, G; Bannwarth, M B; Schulenburg, C; Steffen, V; Jankowska, D; Pohl, M; Rossi, R M; Maniura-Weber, K; Boesel, L F; Richter, M

    2016-06-20

    Silicate nanoparticles with immobilized FRET-based biosensors were developed for the detection of glucose and maltose. Immobilization of the protein biosensor in the nanoparticle was achieved through specific interaction between the hexa-histidine tag of the protein and a calcium-silicate complex of the silica matrix. Encapsulation of the biosensors preserved the affinity for the respective sugar. Compared to the free biosensors, encapsulation had a stabilizing effect on the biosensor towards chemical and thermal denaturation. The demonstrated immobilization strategy for specific sensing proteins paves the way towards the development of protein-inorganic nanostructures for application in metabolite analyses. PMID:26811852

  8. Cancer therapy improvement with mesoporous silica nanoparticles combining targeting, drug delivery and PDT.

    PubMed

    Gary-Bobo, Magali; Hocine, Ouahiba; Brevet, David; Maynadier, Marie; Raehm, Laurence; Richeter, Sébastien; Charasson, Virginie; Loock, Bernard; Morère, Alain; Maillard, Philippe; Garcia, Marcel; Durand, Jean-Olivier

    2012-02-28

    The synthesis of mesoporous silica nanoparticles (MSN) covalently encapsulating fluoresceine or a photosensitizer, functionalized with galactose on the surface is described. Confocal microscopy experiments demonstrated that the uptake of galactose-functionalized MSN by colorectal cancer cells was mediated by galactose receptors leading to the accumulation of the nanoparticles in the endosomal and lysosomal compartments. The MSN functionalized with a photosensitizer and galactose were loaded with the anti-cancer drug camptothecin. Those MSN combining drug delivery and photodynamic therapy were tested on three cancer cell lines and showed a dramatic enhancement of cancer cell death compared to separate treatments. PMID:22178618

  9. Functional silica nanoparticles synthesized by water-in-oil microemulsion processes.

    PubMed

    Aubert, Tangi; Grasset, Fabien; Mornet, Stéphane; Duguet, Etienne; Cador, Olivier; Cordier, Stéphane; Molard, Yann; Demange, Valérie; Mortier, Michel; Haneda, Hajime

    2010-01-15

    Water-in-oil (W/O) microemulsion is a well-suitable confined reacting medium for the synthesis of structured functional nanoparticles of controlled size and shape. During the last decade, it allowed the synthesis of multi-functional silica nanoparticles with morphologies as various as core-shell, homogenous dispersion or both together. The morphology and properties of the different intermediates and final materials obtained through this route are discussed in the light of UV-Vis-NIR spectroscopy, dynamic light scattering (DLS) and X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and magnetometer SQUID analysis. PMID:19875127

  10. Activators generated by electron transfer for atom transfer radical polymerization of styrene in the presence of mesoporous silica nanoparticles

    SciTech Connect

    Khezri, Khezrollah; Roghani-Mamaqani, Hossein

    2014-11-15

    Graphical abstract: Effect of mesoporous silica nanoparticles (MCM-41) on the activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP) is investigated. Decrement of conversion and number average molecular weight and also increment of polydispersity index (PDI) values are three main results of addition of MCM-41 nanoparticles. Incorporation of MCM-41 nanoparticles in the polystyrene matrix can clearly increase thermal stability and decrease glass transition temperature of the nanocomposites. - Highlights: • Spherical morphology, hexagonal structure, and high surface area with regular pore diameters of the synthesized MCM-41 nanoparticles are examined. • AGET ATRP of styrene in the presence of MCM-41 nanoparticles is performed. • Effect of MCM-41 nanoparticles addition on the polymerization rate, conversion and molecular weights of the products are discussed. • Improvement in thermal stability of the nanocomposites and decreasing T{sub g} values was also observed by incorporation of MCM-41 nanoparticles. - Abstract: Activator generated by electron transfer for atom transfer radical polymerization was employed to synthesize well-defined mesoporous silica nanoparticles/polystyrene composites. Inherent features of spherical mesoporous silica nanoparticles were evaluated by nitrogen adsorption/desorption isotherm, X-ray diffraction and scanning electron microscopy analysis techniques. Conversion and molecular weight evaluations were carried out using gas and size exclusion chromatography respectively. By the addition of only 3 wt% mesoporous silica nanoparticles, conversion decreases from 81 to 58%. Similarly, number average molecular weight decreases from 17,116 to 12,798 g mol{sup −1}. However, polydispersity index (PDI) values increases from 1.24 to 1.58. A peak around 4.1–4.2 ppm at proton nuclear magnetic resonance spectroscopy results clearly confirms the living nature of the polymerization. Thermogravimetric

  11. Functionalized magnetic mesoporous silica nanoparticles for U removal from low and high pH groundwater.

    PubMed

    Li, Dien; Egodawatte, Shani; Kaplan, Daniel I; Larsen, Sarah C; Serkiz, Steven M; Seaman, John C

    2016-11-01

    U(VI) species display limited adsorption onto sediment minerals and synthetic sorbents in pH <4 or pH >8 groundwater. In this work, magnetic mesoporous silica nanoparticles (MMSNs) with magnetite nanoparticle cores were functionalized with various organic molecules using post-synthetic methods. The functionalized MMSNs were characterized using N2 adsorption-desorption isotherms, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), (13)C cross polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy, and powder X-ray diffraction (XRD), which indicated that mesoporous silica (MCM-41) particles of 100-200nm formed around a core of magnetic iron oxide, and the functional groups were primarily grafted into the mesopores of ∼3.0nm in size. The functionalized MMSNs were effective for U removal from pH 3.5 and 9.6 artificial groundwater (AGW). Functionalized MMSNs removed U from the pH 3.5 AGW by as much as 6 orders of magnitude more than unfunctionalized nanoparticles or silica and had adsorption capacities as high as 38mg/g. They removed U from the pH 9.6 AGW as much as 4 orders of magnitude greater than silica and 2 orders of magnitude greater than the unfunctionalized nanoparticles with adsorption capacities as high as 133mg/g. These results provide an applied solution for treating U contamination that occurs at extreme pH environments and a scientific foundation for solving critical industrial issues related to environmental stewardship and nuclear power production. PMID:27341378

  12. Mechanical characteristics of mesenchymal stem cells under impact of silica-based nanoparticles

    NASA Astrophysics Data System (ADS)

    Ogneva, Irina V.; Buravkov, Sergey V.; Shubenkov, Alexander N.; Buravkova, Ludmila B.

    2014-06-01

    Silica-based nanoparticles (NPs) pose great potential for medical and biological applications; however, their interactions with living cells have not been investigated in full. The objective of this study was to analyze the mechanical characteristics of mesenchymal stem cells when cultured in the presence of silica (Si) and silica-boron (SiB) nanoparticles. Cell stiffness was measured using atomic force microscopy; F-actin structure was evaluated using TRITC-phalloidin by confocal microscopy. The obtained data suggested that the cell stiffness increased within the following line: `Control' - `Si' - `SiB' (either after 1-h cultivation or 24-h incubation). Moreover, the cell stiffness was found to be higher after 1-h cultivation as compared to 24-h cultivation. This result shows that there is a two-phase process of particle diffusion into cells and that the particles interact directly with the membrane and, further, with the submembranous cytoskeleton. Conversely, the intensity of phalloidin fluorescence dropped within the same line: Control - Si - SiB. It could be suggested that the effects of silica-based particles may result in structural reorganization of cortical cytoskeleton with subsequent stiffness increase and concomitant F-actin content decrease (for example, in recruitment of additional actin-binding proteins within membrane and regrouping of actin filaments).

  13. Inorganic/Organic Hybrid Silica Nanoparticles as a Nitric Oxide Delivery Scaffold.

    PubMed

    Shin, Jae Ho; Schoenfisch, Mark H

    2008-01-01

    The preparation and characterization of nitric oxide (NO)-releasing silica particles formed following the synthesis of N-diazeniumdiolate-modified aminoalkoxysilanes are reported. Briefly, an aminoalkoxysilane solution was prepared by dissolving an appropriate amount of aminoalkoxysilane in a mixture of ethanol, methanol, and sodium methoxide (NaOMe) base. The silane solution was reacted with NO (5 atm) to form N-diazeniumdiolate NO donor moieties on the amino-alkoxysilanes. Tetraethoxy- or tetramethoxysilane (TEOS or TMOS) was then mixed with different ratios of N-diazeniumdiolate-modified aminoalkoxysilane (10 - 75 mol%, balance TEOS or TMOS). Finally, the silane mixture was added into ethanol in the presence of an ammonia catalyst to form NO donor silica nanoparticles via a sol-gel process. This synthetic approach allows for the preparation of NO delivery silica scaffolds with remarkably improved NO storage and release properties, surpassing all macromolecular NO donor systems reported to date with respect to NO payload (11.26μmol·mg(-1)), maximum NO release amount (357000 ppb·mg(-1)), NO release half-life (253 min), and NO release duration (101 h). The N-diazeniumdiolate-modified silane monomers and the resulting silica nanoparticles were characterized by (29)Si nuclear magnetic resonance (NMR) spectroscopy, UV-visible spectroscopy, chemiluminescence, atomic force microscopy (AFM), gas adsorption-desorption isotherms, and elemental analysis. PMID:23833394

  14. Mechanical characteristics of mesenchymal stem cells under impact of silica-based nanoparticles

    PubMed Central

    2014-01-01

    Silica-based nanoparticles (NPs) pose great potential for medical and biological applications; however, their interactions with living cells have not been investigated in full. The objective of this study was to analyze the mechanical characteristics of mesenchymal stem cells when cultured in the presence of silica (Si) and silica-boron (SiB) nanoparticles. Cell stiffness was measured using atomic force microscopy; F-actin structure was evaluated using TRITC-phalloidin by confocal microscopy. The obtained data suggested that the cell stiffness increased within the following line: ‘Control’ - ‘Si’ - ‘SiB’ (either after 1-h cultivation or 24-h incubation). Moreover, the cell stiffness was found to be higher after 1-h cultivation as compared to 24-h cultivation. This result shows that there is a two-phase process of particle diffusion into cells and that the particles interact directly with the membrane and, further, with the submembranous cytoskeleton. Conversely, the intensity of phalloidin fluorescence dropped within the same line: Control - Si - SiB. It could be suggested that the effects of silica-based particles may result in structural reorganization of cortical cytoskeleton with subsequent stiffness increase and concomitant F-actin content decrease (for example, in recruitment of additional actin-binding proteins within membrane and regrouping of actin filaments). PMID:24948901

  15. Stable Encapsulation of Air in Mesoporous Silica Nanoparticles: Fluorocarbon-Free Nanoscale Ultrasound Contrast Agents.

    PubMed

    Yildirim, Adem; Chattaraj, Rajarshi; Blum, Nicholas T; Goldscheitter, Galen M; Goodwin, Andrew P

    2016-06-01

    While gas-filled micrometer-sized ultrasound contrast agents vastly improve signal-to-noise ratios, microbubbles have short circulation lifetimes and poor extravasation from the blood. Previously reported fluorocarbon-based nanoscale contrast agents are more stable but their contrast is generally lower owing to their size and dispersity. The contrast agents reported here are composed of silica nanoparticles of ≈100 nm diameter that are filled with ≈3 nm columnar mesopores. Functionalization of the silica surface with octyl groups and resuspension with Pluronic F127 create particles with pores that remain filled with air but are stable in buffer and serum. Administration of high intensity focused ultrasound (HIFU) allows sensitive imaging of the silica nanoparticles down to 10(10) particles mL(-1) , with continuous imaging for at least 20 min. Control experiments with different silica particles supported the hypothesis that entrapped air could be pulled into bubble nuclei, which can then in turn act as acoustic scatterers. This process results in very little hemolysis in whole blood, indicating potential for nontoxic blood pool imaging. Finally, the particles are lyophilized and reconstituted or stored in PBS (phosphate-buffered saline, at least for four months) with no loss in contrast, indicating stability to storage and reformulation. PMID:26990167

  16. Fluorescent Cy5 silica nanoparticles for cancer cell imaging

    NASA Astrophysics Data System (ADS)

    O'Connell, Claire; Nooney, Robert I.; Glynn, MacDara; Ducree, Jens; McDonagh, Colette

    2015-08-01

    Cancer is a leading cause of death worldwide, with metastasis responsible for the majority of cancer-related deaths. Circulating tumour cells (CTCs) play a central role in metastasis. Fluorescent silica particles (NPs), of diameter ~50 nm which contain a large concentration of Cy5 dye molecules and are extremely bright, have been developed to detect these rare CTCs. Due to this brightness, the particles have superior performance compared to single Cy5 dye molecule labels, for detecting cancer cells. Fluorescence measurements show that the NPs are almost 100 times brighter than the free dye. They do not photo bleach as readily and, due to the biocompatible silica surface, they can be chemically modified, layer-by-layer, in order to bind to cells. The choice of these chemical layers, in particular the NP to antibody linker, along with the incubation period and type of media used in the incubation, has a strong influence on the specific binding abilities of the NPs. In this work, NPs have been shown to selectively bind to the MCF-7 cell line by targeting epithelial cellular adhesion molecule (EpCAM) present on the MCF-7 cell membrane by conjugating anti-EpCAM antibody to the NP surface. Results have shown a high signal to noise ratio for this cell line in comparison to a HeLa control line. NP attachment to cells was verified qualitatively with the use of fluorescence microscopy and quantitatively using image analysis methods. Once the system has been optimised, other dyes will be doped into the silica NPs and their use in multiplexing will be investigated.

  17. Inside-out disruption of silica/gold core-shell nanoparticles by pulsed laser irradiation.

    PubMed

    Prasad, V; Mikhailovsky, A; Zasadzinski, J A

    2005-08-01

    Near-infrared (NIR) femtosecond laser irradiation of metallodielectric core-shell silica-gold (SiO(2)-Au) nanoparticles can induce extreme local heating prior to the rapid dissipation of energy caused by the large surface area/volume ratio of nanometer-scale objects. At low pulse intensities, the dielectric silica core is removed, leaving an incomplete gold shell behind. The gold shells with water inside and out still efficiently absorb NIR light from subsequent pulses, showing that a complete shell is not necessary for absorption. At higher pulse intensities, the gold shell itself is melted and disrupted, leading to smaller, approximately 20-nm gold nanoparticles. Spectroscopic measurements show that this disruption is accompanied by optical hole burning of the peak at 730 nm and formation of a new peak at 530 nm. The silica removal and gold shell disruption confirms significant temperature rise of the core-shall nanoparticle. However, the entire process leads to minimal heating of the bulk solution due to the low net energy input. PMID:16042490

  18. Bifunctional silica nanoparticles for the exploration of biofilms of Pseudomonas aeruginosa.

    PubMed

    Mauline, L; Gressier, M; Roques, C; Hammer, P; Ribeiro, S J L; Caiut, J M A; Menu, M-J

    2013-01-01

    Luminescent silica nanoparticles are frequently employed for biotechnology applications mainly because of their easy functionalization, photo-stability, and biocompatibility. Bifunctional silica nanoparticles (BSNPs) are described here as new efficient tools for investigating complex biological systems such as biofilms. Photoluminescence is brought about by the incorporation of a silylated ruthenium(II) complex. The surface properties of the silica particles were designed by reaction with amino-organosilanes, quaternary ammonium-organosilanes, carboxylate-organosilanes and hexamethyldisilazane. BSNPs were characterized extensively by DRIFT, (13)C and (29)Si solid state NMR, XPS, and photoluminescence. Zeta potential and contact angle measurements exhibited various surface properties (hydrophilic/hydrophobic balance and electric charge) according to the functional groups. Confocal laser scanning microscopy (CLSM) measurements showed that the spatial distribution of these nanoparticles inside a biofilm of Pseudomonas aeruginosa PAO1 depends more on their hydrophilic/hydrophobic characteristics than on their size. CLSM observations using two nanosized particles (25 and 68 nm) suggest that narrow diffusion paths exist through the extracellular polymeric substances matrix. PMID:23805884

  19. Improvements of physical, mechanical and biodegradation properties of polybutadiene rubber insulators by chitosan and silica nanoparticles.

    PubMed

    Saboktakin, Amin; Saboktakin, Mohammadreza

    2016-10-01

    1,4-cis-Polybutadiene rubber(1,4-cis pBR) as an insulation material is developing that will provide superior thermal insulation properties, flexibility, toughness by natural polymers such as chitosan(CS) and silica nanoparticles. This material is widely used in the insulation industries specially architecture. This research concerns physical, mechanical properties and also biodegradation of 1,4-cis pBR, which to be composed with the natural polymers such as CS. Silica nanoparticles were used as filler to improve the physical and mechanical properties of 1,4-cis pBR. To evaluating its physical and mechanical properties, stretching and bending and impact tests were used and the results show some improvement in these properties. Our observations show that temperature plays an important role as main factor in order to improve the mechanical properties of nanocomposites. Similar improvements in tensile modulus and strength have been observed for 1,4-cis pBR/CS-silica nanoparticles. PMID:27353394

  20. The Influence of Silica Nanoparticles on Ionic Liquid Behavior: A Clear Difference between Adsorption and Confinement

    PubMed Central

    Wang, Yaxing; Li, Cheng; Guo, Xiaojing; Wu, Guozhong

    2013-01-01

    The phase behaviors of ionic liquids (ILs) confined in nanospace and adsorbed on outer surface of nanoparticles are expected to be different from those of the bulk. Anomalous phase behaviors of room temperature ionic liquid tributylhexadecylphosphonium bromide (P44416Br) confined in ordered mesoporous silica nanoparticles with average pore size 3.7 nm and adsorbed on outer surface of the same silica nanoparticles were reported. It was revealed that the melting points (Tm) of confined and adsorbed ILs depressed significantly in comparison with the bulk one. The Tm depressions for confined and adsorbed ILs are 8 °C and 14 °C, respectively. For comparison with the phase behavior of confined P44416Br, 1-butyl-3-methylimidazolium bromide (BmimBr) was entrapped within silica nanopores, we observed an enhancement of 50 °C in Tm under otherwise similar conditions. The XRD analysis indicates the formation of crystalline-like phase under confinement, in contrast to the amorphous phase in adsorbed IL. It was confirmed that the behavior of IL has clear difference. Moreover, the complex π-π stacking and H-bonding do not exist in the newly proposed phosphonium-based IL in comparison with the widely studied imidazolium-based IL. The opposite change in melting point of P44416Br@SiO2 and BmimBr@SiO2 indicates that the cationic species plays an important role in the variation of melting point. PMID:24145752

  1. Doxorubicin-loaded mesoporous silica nanoparticle composite nanofibers for long-term adjustments of tumor apoptosis

    NASA Astrophysics Data System (ADS)

    Yuan, Ziming; Pan, Yue; Cheng, Ruoyu; Sheng, Lulu; Wu, Wei; Pan, Guoqing; Feng, Qiming; Cui, Wenguo

    2016-06-01

    There is a high local recurrence (LR) rate in breast-conserving therapy (BCT) and enhancement of the local treatment is promising as a way to improve this. Thus we propose a drug delivery system using doxorubicin (DOX)-loaded mesoporous silica nanoparticle composite nanofibers which can release anti-tumor drugs in two phases—burst release in the early stage and sustained release at a later stage—to reduce the LR of BCT. In the present study, we designed a novel composite nanofibrous scaffold to realize the efficient release of drugs by loading both DOX and DOX-loaded mesoporous silica nanoparticles into an electrospun PLLA nanofibrous scaffold. In vitro results demonstrated that this kind of nanomaterial can release DOX in two phases, and the results of in vivo experiments showed that this hybrid nanomaterial significantly inhibited the tumor growth in a solid tumor model. Histopathological examination demonstrated that the apoptosis of tumor cells in the treated group over a 10 week period was significant. The anti-cancer effects were also accompanied with decreased expression of Bcl-2 and TNF-α, along with up-regulation of Bax, Fas and the activation of caspase-3 levels. The present study illustrates that the mesoporous silica nanoparticle composite nanofibrous scaffold could have anti-tumor properties and could be further developed as adjuvant therapeutic protocols for the treatment of cancer.

  2. Dopamine/Silica Nanoparticle Assembled, Microscale Porous Structure for Versatile Superamphiphobic Coating.

    PubMed

    Li, Fang; Du, Miao; Zheng, Qiang

    2016-02-23

    Artificial superamphiphobic surfaces, which could repel both water and low surface tension organic liquids, have been limited to particular kinds of materials or surfaces thus far. In this work, a kind of microscale porous coating was developed. Taking dopamine and hydrophilic fumed silica nanoparticles as initial building blocks, microscale porous coating was constructed via ice templation. Polydopamine bound silica nanoparticles together to form a porous structure network and rendered the coating to have potential for further postfunctionalization. After two-step CVD, the microscale porous coating changes from superhydrophilic to superamphiphobic, exhibiting super-repellency to droplets with surface tension of 73-23 mN/m. The influences of concentration of initial dopamine, hydrophilic fumed silica nanoparticles, and dry conditions on the formation of the porous structure have been studied to optimize the conditions. Coatings with different pore sizes and pore heights have been fabricated to discover the relationship between the structure parameters and the repellency of the porous coatings. Only with optimal pore size and pore height can the porous coating display superamphiphobicity. Compared with nanoscale, the microscale structure favors the achievement of superamphiphobicity. Given the outstanding adhesive ability of polydopamine, the superamphiphobic coatings have been successfully applied to various materials including artificial materials and natural materials. PMID:26828414

  3. Iron Nanoparticles-Encapsulating Silica Microspheres for Arterial Embolization Hyperthermia

    NASA Astrophysics Data System (ADS)

    Li, Z.; Kawashita, M.

    2011-10-01

    We attempted to prepare α-Fe-encapsulating silica (αFeSi) microspheres by a sol-gel process using tetramethoxysilane (TMOS) in water-in-oil emulsion. The effect of preparation conditions on the structure, magnetic and heating properties of resultant products were investigated. Oil phase consisted of kerosene with 32 wt% of surfactants (sorbitan monooleate / sorbitan monostearate in 3:1 weight ratio). Water phase consisted of TMOS, ethanol (CH2CH3OH), water and iron nitrate (Fe(NO3)3·9H2O) with TMOS / CH2CH3OH/H2O/Fe3+ in 1:7.4:16.2:0.4~1.2 molar ratio. Fe3+-containing silica gel (FeSiG) microspheres 5 to 30 μm in size were successfully obtained by adding the water phase into the oil phase at 60 °C under stirring of 1500 rpm for 100 min. αFeSi microspheres was obtained by heating the FeSiG microspheres at 850°C in argon atmosphere. The obtained αFeSi microspheres have a saturation magnetization (Ms) up to 21 emu g-1 and a coercive force (Hc) of 133 Oe. The in vitro heating generation was evaluated under an alternating current (AC) magnetic field of 300 Oe and 100 kHz.

  4. Making silica nanoparticle-covered graphene oxide nanohybrids as general building blocks for large-area superhydrophilic coatings.

    PubMed

    Kou, Liang; Gao, Chao

    2011-02-01

    We report a facile strategy to synthesize silica nanoparticles-coated graphene oxide (GO-SiO2) nanohybrids in a water-alcohol mixture at room temperature. AFM observations revealed that silica nanoparticles with ca. 50 nm in size were densely and evenly covered on graphene oxide sheets. Due to the space layer of silica nanoparticles, micro-scale GO-SiO2 hybrid plates could be individually dispersed in water and polar organic solvents, promising good solution-based processibility. The growth process of GO-supported silica is traced by TGA and XRD measurements, showing that 24 hours is enough to achieve a fine cover effect for the disappearance of (002) diffraction peak of GO. Based on the high dense overlaying of silica nanoparticles, up to micro-scale silica sheets with thickness of ca. 8 nm were readily fabricated by burning GO-SiO2 at 650 °C in air. Likewise, a centimeter-scale semitransparent film of silica nanosheets was prepared by calcining a GO-SiO2 film. Interestingly, the GO-SiO2 nanohybrids exhibit excellent hydrophilic nature and can be directly applied as a general kind of building blocks to construct large-area superhydrophilic surfaces on arbitrary substrates (e.g., lotus leaf, ceramic tile and polypropylene) through the simple drop-coating method. Such a coating methodology paves the way for making large-area superhydrophilic surface without extra process treatments and damaging the intrinsic structure of substrates. PMID:21109865

  5. Synthesis and magnetic properties of DyMnO3 nanoparticles in mesoporous silica

    NASA Astrophysics Data System (ADS)

    Tajiri, Takayuki; Kohno, Atsushi; Hamamoto, Kenta; Ando, Yuhki; Deguchi, Hiroyuki; Mito, Masaki

    2013-08-01

    We synthesized nanoparticles of the perovskite manganite DyMnO3 in pores of mesoporous silica SBA-15 and investigated their magnetic properties. X-ray diffraction patterns of the nanoparticles indicated successful synthesis of the DyMnO3 nanoparticles with a particle size of about 10 nm in the pores of SBA-15. The temperature dependence of the DC magnetic susceptibility for the DyMnO3 nanoparticles exhibited a pronounced magnetic irreversibility between the field-cooling and the zero-field-cooling susceptibility due to the blocking phenomena and indicated a change of the magnetic exchange interactions from those for the bulk crystal. The in-phase susceptibility χ' and the out-of-phase susceptibility χ″ of the AC susceptibility for the nanoparticles exhibited a peak at the blocking temperature, and that peak shifted toward higher temperature with increasing frequency. Magnetization curves for the nanoparticles were reproduced by using a Langevin function and exhibited a hysteresis loop at temperatures below the blocking temperature. Magnetic size effects and superparamagnetic behaviors were observed in the DyMnO3 nanoparticles.

  6. Interaction of lysozyme protein with different sized silica nanoparticles and their resultant structures

    NASA Astrophysics Data System (ADS)

    Yadav, Indresh; Aswal, V. K.; Kohlbrecher, J.

    2016-05-01

    The interaction of model protein-lysozyme with three different sized anionic silica nanoparticles has been studied by UV-vis spectroscopy, dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The surface area and curvature of the nanoparticles change with size, which significantly influence their interaction with protein. The lysozyme adsorbs on the surface of the nanoparticles due to electrostatic attraction and leads to the phase transformation from one phase (clear) to two-phase (turbid) of the nanoparticle-protein system. The dominance of lysozyme induced short-range attraction over long-range electrostatic repulsion between nanoparticles is responsible for phase transformation and modeled by the two-Yukawa potential. The magnitude of the attractive interaction increases with the size of the nanoparticles as a result the phase transformation commences relatively at lower concentration of lysozyme. The structure of the nanoparticle-protein system in two-phase is characterized by the diffusion limited aggregate type of mass fractal morphology.

  7. Bioavailability of Silica, Titanium Dioxide, and Zinc Oxide Nanoparticles in Rats.

    PubMed

    Kim, Mi-Kyung; Lee, Jeong-A; Jo, Mi-Rae; Choi, Soo-Jin

    2016-06-01

    Inorganic nanoparticles have been widely applied to various industrial fields and biological applications. However, the question as to whether nanoparticles are more efficiently absorbed into the systemic circulation than bulk-sized materials remains to be unclear. In the present study, the physico-chemical and dissolution properties of the most extensively developed inorganic nanoparticles, such as silica (SiO2), titanium dioxide (TiO2), and zinc oxide (ZnO), were analyzed, as compared with bulk-sized particles. Furthermore, the bioavailability of nanoparticles versus their bulk counterparts was evaluated in rats after a single oral administration and intravenous injection, respectively. The results demonstrated that all bulk materials had slightly higher crystallinity than nanoparticles, however, their dissolution properties were not affected by particle size. No significant difference in oral absorption and bioavailability of both SiO2 and TiO2 was found between nano- and bulk-sized materials, while bulk ZnO particles were more bioavailable in the body than ZnO nanoparticles. These finding will provide critical information to apply nanoparticles with high efficiency as well as to predict their toxicity potential. PMID:27427756

  8. Microwave-induced synthesis of highly dispersed gold nanoparticles within the pore channels of mesoporous silica

    NASA Astrophysics Data System (ADS)

    Gu, Jinlou; Fan, Wei; Shimojima, Atsushi; Okubo, Tatsuya

    2008-04-01

    Highly dispersed gold nanoparticles have been incorporated into the pore channels of SBA-15 mesoporous silica through a newly developed strategy assisted by microwave radiation (MR). The sizes of gold are effectively controlled attributed to the rapid and homogeneous nucleation, simultaneous propagation and termination of gold precursor by MR. Diol moieties with high dielectric and dielectric loss constants, and hence a high microwave activation, were firstly introduced to the pore channels of SBA-15 by a simple addition reaction between amino group and glycidiol and subsequently served as the reduction centers for gold nanoparticles. Extraction of the entrapped gold from the nanocomposite resulted in milligram quantities of gold nanoparticles with low dispersity. The successful assembly process of diol groups and formation of gold nanoparticles were monitored and tracked by solid-state NMR and UV-vis measurements. Characterization by small angle X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the incorporation of gold nanoparticles would not breakup the structural integrity and long-range periodicity of SBA-15. The gold nanoparticles had a narrow size distribution with diameters in the size range of 5-10 nm through TEM observation. The average particles size is 7.9 nm via calculation by the Scherrer formula and TEM measurements. Nitrogen adsorption and desorption isotherms gave further evidence that the employed method was efficient and gold nanoparticles were successfully incorporated into the pore channels of SBA-15.

  9. Rheological Properties of Silica Nanoparticles in Brine and Brine-Surfactant Systems

    NASA Astrophysics Data System (ADS)

    Pales, Ashley; Kinsey, Erin; Li, Chunyan; Mu, Linlin; Bai, Lingyun; Clifford, Heather; Darnault, Christophe

    2016-04-01

    Rheological Properties of Silica Nanoparticles in Brine and Brine-Surfactant Systems Ashley R. Pales, Erin Kinsey, Chunyan Li, Linlin Mu, Lingyun Bai, Heather Clifford, and Christophe J. G. Darnault Department of Environmental Engineering and Earth Sciences, Laboratory of Hydrogeoscience and Biological Engineering, L.G. Rich Environmental Laboratory, Clemson University, Clemson, SC, USA Nanofluids are suspensions of nanometer sized particles in any fluid base, where the nanoparticles effect the properties of the fluid base. Commonly, nanofluids are water based, however, other bases such as ethylene-glycol, glycerol, and propylene-glycol, have been researched to understand the rheological properties of the nanofluids. This work aims to understand the fundamental rheological properties of silica nanoparticles in brine based and brine-surfactant based nanofluids with temperature variations. This was done by using variable weight percent of silica nanoparticles from 0.001% to 0.1%. Five percent brine was used to create the brine based nanofluids; and 5% brine with 2CMC of Tween 20 nonionic surfactant (Sigma-Aldrich) was used to create the brine-surfactant nanofluid. Rheological behaviors, such as shear rate, shear stress, and viscosity, were compared between these nanofluids at 20C and at 60C across the varied nanoparticle wt%. The goal of this work is to provide a fundamental basis for future applied testing for enhanced oil recovery. It is hypothesized that the addition of surfactant will have a positive impact on nanofluid properties that will be useful for enhance oil recovery. Differences have been observed in preliminary data analysis of the rheological properties between these two nanofluids indicating that the surfactant is having the hypothesized effect.

  10. Monodisperse Mesoporous Carbon Nanoparticles from Polymer/Silica Self-Aggregates and Their Electrocatalytic Activities.

    PubMed

    Huang, Xiaoxi; Zhou, Li-Jing; Voiry, Damien; Chhowalla, Manish; Zou, Xiaoxin; Asefa, Tewodros

    2016-07-27

    In our quest to make various chemical processes sustainable, the development of facile synthetic routes and inexpensive catalysts can play a central role. Herein we report the synthesis of monodisperse, polyaniline (PANI)-derived mesoporous carbon nanoparticles (PAMCs) that can serve as efficient metal-free electrocatalysts for the hydrogen peroxide reduction reaction (HPRR) as well as the oxygen reduction reaction (ORR) in fuel cells. The materials are synthesized by polymerization of aniline with the aid of (NH4)2S2O8 as oxidant and colloidal silica nanoparticles as templates, then carbonization of the resulting PANI/silica composite material at different high temperatures, and finally removal of the silica templates from the carbonized products. The PAMC materials that are synthesized under optimized synthetic conditions possess monodisperse mesoporous carbon nanoparticles with an average size of 128 ± 12 nm and an average pore size of ca. 12 nm. Compared with Co3O4, a commonly used electrocatalyst for HPRR, these materials show much better catalytic activity for this reaction. In addition, unlike Co3O4, the PAMCs remain relatively stable during the reaction, under both basic and acidic conditions. The nanoparticles also show good electrocatalytic activity toward ORR. Based on the experimental results, PAMCs' excellent electrocatalytic activity is attributed partly to their heteroatom dopants and/or intrinsic defect sites created by vacancies in their structures and partly to their high porosity and surface area. The reported synthetic method is equally applicable to other polymeric precursors (e.g., polypyrrole (PPY)), which also produces monodisperse, mesoporous carbon nanoparticles in the same way. The resulting materials are potentially useful not only for electrocatalysis of HPRR and ORR in fuel cells but also for other applications where high surface area, small sized, nanostructured carbon materials are generally useful for (e.g., adsorption

  11. Anti-amyloid compounds protect from silica nanoparticle-induced neurotoxicity in the nematode C. elegans

    PubMed Central

    Scharf, Andrea; Gührs, Karl-Heinz; von Mikecz, Anna

    2016-01-01

    Abstract Identifying nanomaterial-bio-interactions are imperative due to the broad introduction of nanoparticle (NP) applications and their distribution. Here, we demonstrate that silica NPs effect widespread protein aggregation in the soil nematode Caenorhabditis elegans ranging from induction of amyloid in nucleoli of intestinal cells to facilitation of protein aggregation in body wall muscles and axons of neural cells. Proteomic screening revealed that exposure of adult C. elegans with silica NPs promotes segregation of proteins belonging to the gene ontology (GO) group of “protein folding, proteolysis and stress response” to an SDS-resistant aggregome network. Candidate proteins in this group include chaperones, heat shock proteins and subunits of the 26S proteasome which are all decisively involved in protein homeostasis. The pathway of protein homeostasis was validated as a major target of silica NPs by behavioral phenotyping, as inhibitors of amyloid formation rescued NP-induced defects of locomotory patterns and egg laying. The analysis of a reporter worm for serotonergic neural cells revealed that silica NP-induced protein aggregation likewise occurs in axons of HSN neurons, where presynaptic accumulation of serotonin, e.g. disturbed axonal transport reduces the capacity for neurotransmission and egg laying. The results suggest that in C. elegans silica NPs promote a cascade of events including disturbance of protein homeostasis, widespread protein aggregation and inhibition of serotonergic neurotransmission which can be interrupted by compounds preventing amyloid fibrillation. PMID:26444998

  12. Biocompatibility assessment of rice husk-derived biogenic silica nanoparticles for biomedical applications.

    PubMed

    Alshatwi, Ali A; Athinarayanan, Jegan; Periasamy, Vaiyapuri Subbarayan

    2015-02-01

    Synthetic forms of silica have low biocompatibility, whereas biogenic forms have myriad beneficial effects in current toxicological applications. Among the various sources of biogenic silica, rice husk is considered a valuable agricultural biomass material and a cost-effective resource that can provide biogenic silica for biomedical applications. In the present study, highly pure biogenic silica nanoparticles (bSNPs) were successfully harvested from rice husks using acid digestion under pressurized conditions at 120°C followed by a calcination process. The obtained bSNPs were subjected to phase identification analysis using X-ray diffraction, which revealed the amorphous nature of the bSNPs. The morphologies of the bSNPs were observed using transmission electron microscopy (TEM), which revealed spherical particles 10 to 30 nm in diameter. Furthermore, the biocompatibility of the bSNPs with human lung fibroblast cells (hLFCs) was investigated using a viability assay and assessing cellular morphological changes, intracellular ROS generation, mitochondrial transmembrane potential and oxidative stress-related gene expression. Our results revealed that the bSNPs did not have any significant incompatibility in these in vitro cell-based approaches. These preliminary findings suggest that bSNPs are biocompatible, could be the best alternative to synthetic forms of silica and are applicable to food additive and biomedical applications. PMID:25492167

  13. Immunogold labeling reveals subcellular localisation of silica nanoparticles in a human blood-brain barrier model

    NASA Astrophysics Data System (ADS)

    Ye, Dong; Anguissola, Sergio; O'Neill, Tiina; Dawson, Kenneth A.

    2015-05-01

    Subcellular location of nanoparticles has been widely investigated with fluorescence microscopy, via fluorescently labeled antibodies to visualise target antigens in cells. However, fluorescence microscopy, such as confocal or live cell imaging, has generally limited 3D spatial resolution. Conventional electron microscopy can be useful in bridging resolution gap, but still not ideal in resolving subcellular organelle identities. Using the pre-embedding immunogold electron microscopic imaging, we performed accurate examination of the intracellular trafficking and gathered further evidence of transport mechanisms of silica nanoparticles across a human in vitro blood-brain barrier model. Our approach can effectively immunolocalise a variety of intracellular compartments and provide new insights into the uptake and subcellular transport of nanoparticles.Subcellular location of nanoparticles has been widely investigated with fluorescence microscopy, via fluorescently labeled antibodies to visualise target antigens in cells. However, fluorescence microscopy, such as confocal or live cell imaging, has generally limited 3D spatial resolution. Conventional electron microscopy can be useful in bridging resolution gap, but still not ideal in resolving subcellular organelle identities. Using the pre-embedding immunogold electron microscopic imaging, we performed accurate examination of the intracellular trafficking and gathered further evidence of transport mechanisms of silica nanoparticles across a human in vitro blood-brain barrier model. Our approach can effectively immunolocalise a variety of intracellular compartments and provide new insights into the uptake and subcellular transport of nanoparticles. Electronic supplementary information (ESI) available: Nanoparticle characterisation data, preservation of cellular structures, staining controls, optimisation of size amplification via the silver enhancement, and more imaging results from anti-clathrin and anti-caveolin 1

  14. Extended release of ketotifen from silica shell nanoparticle-laden hydrogel contact lenses: in vitro and in vivo evaluation.

    PubMed

    Maulvi, Furqan A; Mangukiya, Mayurkumar A; Patel, Prachi A; Vaidya, Rutvi J; Koli, Akshay R; Ranch, Ketan M; Shah, Dinesh O

    2016-06-01

    Ketotifen an anti-allergic drug delivered via eye drops has major limitations, including poor ocular bioavailability and poor patient compliance. The objective of the research work was to fabricate ketotifen loaded microemulsion laden hydrogels and silica shell nanoparticle-laden (prepared from microemulsion using octyltrimethoxysilane) hydrogels to achieve extended ocular drug delivery. The porous silica shell membrane was synthesized at the liquid interface of microemulsion, which facilitates the prolongation of drug release duration from hydrogels. Drug encapsulated microemulsion and silica shell nanoparticles were dispersed separately in pre-monomer mixture, and fabricated to hydrogel. For comparison, hydrogel with direct drug entrapment was also fabricated. Significant loss in transmittance and physical properties was observed in hydrogels with direct drug entrapment. While, microemulsion and silica shell nanoparticle-laden hydrogels did not show significant effect on transmittance and physical properties. The in vitro drug release data showed extended release of ketotifen from hydrogels in following order: direct loadingsilica shell nanoparticles. The results of cytotoxicity and animal study confirmed the safety of hydrogels. The in vivo pharmacokinetic study showed extended ketotifen release for more than 10 days. The results demonstrated the translational potential of silica shell nanoparticles for extended drug delivery without compromising the critical lens properties. PMID:27178036

  15. One-pot synthesis of monodispersed silica nanoparticles for diarylethene-based reversible fluorescence photoswitching in living cells.

    PubMed

    Jung, Hye-youn; You, Suyeon; Lee, Chaewoon; You, Seungkwon; Kim, Yoonkyung

    2013-09-01

    A small 29 nm monodispersed silica nanoparticle 1a was synthesized as a diarylethene-based reversible fluorescence photoswitch by copolymerizing silane precursors in one-pot including 3a and 4. Reversible photoswitching of nanoparticle 1a was successfully achieved in living cells to show its potential as a highly distinguishable and safe fluorescence probe for cell tracking. PMID:23863959

  16. Surface modification of zinc oxide nanoparticles with amorphous silica alters their fate in the circulation.

    PubMed

    Konduru, Nagarjun V; Murdaugh, Kimberly M; Swami, Archana; Jimenez, Renato J; Donaghey, Thomas C; Demokritou, Philip; Brain, Joseph D; Molina, Ramon M

    2016-08-01

    Nanoparticle (NP) pharmacokinetics and biological effects are influenced by many factors, especially surface physicochemical properties. We assessed the effects of an amorphous silica coating on the fate of zinc after intravenous (IV) injection of neutron activated uncoated (65)ZnO or silica-coated (65)ZnO NPs in male Wistar Han rats. Groups of IV-injected rats were sequentially euthanized, and 18 tissues were collected and analyzed for (65)Zn radioactivity. The protein coronas on each ZnO NP after incubation in rat plasma were analyzed by SDS-PAGE gel electrophoresis and mass spectrometry of selected gel bands. Plasma clearance for both NPs was biphasic with rapid initial and slower terminal clearance rates. Half-lives of plasma clearance of silica-coated (65)ZnO were shorter (initial - <1 min; terminal - 2.5 min) than uncoated (65)ZnO (initial - 1.9 min; terminal - 38 min). Interestingly, the silica-coated (65)ZnO group had higher (65)Zn associated with red blood cells and higher initial uptake in the liver. The (65)Zn concentrations in all the other tissues were significantly lower in the silica-coated than uncoated groups. We also found that the protein corona formed on silica-coated ZnO NPs had higher amounts of plasma proteins, particularly albumin, transferrin, A1 inhibitor 3, α-2-hs-glycoprotein, apoprotein E and α-1 antitrypsin. Surface modification with amorphous silica alters the protein corona, agglomerate size, and zeta potential of ZnO NPs, which in turn influences ZnO biokinetic behavior in the circulation. This emphasizes the critical role of the protein corona in the biokinetics, toxicology and nanomedical applications of NPs. PMID:26581431

  17. The study of poly(L-lactide) grafted silica nanoparticles on the film blowing of poly(L-lactide)

    NASA Astrophysics Data System (ADS)

    Wu, Feng; Liu, Zhengying; Yang, Mingbo

    2015-05-01

    PLA nanocomposites are prepared by us, and to better develop the function of silica nanoparticle, the surface of silica nanoparticles are modified by introducing PLA chains via "grafting to" method in our research. According to the results of 1H NMR and TGA, it shows that the PLA grafted Silica nanoparticles are successfully synthesized by controlling the reaction condition, and the molecular weight of the grafted PLA chains is relatively as high as 22 400 g/mol. PLA Nanocomposites with modified nanoparticles are prepared using a convenient melt blending method to guarantee well-distribution of the particles. The well-dispersion state of silica nanospheres is confirmed by Scan Electrical Micrograph (SEM) technology. From the dynamic shear rheology tests, the strain and time sweep both reveal that stability networks are formed in these nanocomposites. And the frequency sweep shows that the nanoparticles with long grafted chains dramatically enhanced the storage and viscosity of the pure PLA. The rheology testing suggests that strong particle-matrix interactions between molecularly/nano-level dispersed grafted silica and PLA chains formed; and the elongational viscosity of PLA has been markedly improved with the addition of the nanoparticle. The effect of modified nanoparticles on the thermal properties of PLA has also been studied by us using Differential Scanning Calorimetry (DSC). It reveals that the crystallization rate of PLA has been improved as the long grafted chains play as the nucleation sites for PLA. Finally based on these rheology and crystallization researches, the nanocomposites are used to prepare PLA blowing films. Compared to pure PLA and PLA/unmodified silica nanocomposites, the results show that the stability of the film blowing has been greatly improved and the blow-up ratio has been increased with the addition of PLA grafted nanoparticles. The modified nanoparticles hold significant candidates to improve the thermal stability and the

  18. Compaction of DNA with Lipid Modified Silica Nanoparticles

    NASA Astrophysics Data System (ADS)

    Savarala, Sushma; Wunder, Stephanie L.; Ilies, Marc

    2012-02-01

    There is an increasing interest in modified inorganic nanoparticles, polymers or hybrid polymer-inorganic nanoparticles for use in DNA transfection, rather than viral vectors or liposomes. Adsorption of the DNA to the nanoparticles prevents enzymatic degradation of the DNA, although the reason for this protection is not completely understood. In order to compact the negatively charged DNA, a positively charged surface is required, and for transfection applications, the nanosystems must remain stable in suspension. It is also useful to minimize the amount of cytotoxic cationic lipid needed for DNA compaction in delivery applications. Here we investigate the colloidal stability of supported lipid bilayers (SLBs) composed of mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC, 14:0 PC) and 1,2-dimyristoyl-3-trimethylammonium-propane (DMTAP, 14:0 TAP), and their ability to compact plasmid DNA. Ionic strengths and DMPC/DMTAP ratios that resulted in SLB formation, no excess small unilamellar vesicles (SUVs) in the suspensions, and colloidal stability, were determined. DNA/SLB/lipid ratios that resulted in compaction were then investigated.

  19. In Vivo Integrity and Biological Fate of Chelator-Free Zirconium-89-Labeled Mesoporous Silica Nanoparticles

    PubMed Central

    2015-01-01

    Traditional chelator-based radio-labeled nanoparticles and positron emission tomography (PET) imaging are playing vital roles in the field of nano-oncology. However, their long-term in vivo integrity and potential mismatch of the biodistribution patterns between nanoparticles and radio-isotopes are two major concerns for this approach. Here, we present a chelator-free zirconium-89 (89Zr, t1/2 = 78.4 h) labeling of mesoporous silica nanoparticle (MSN) with significantly enhanced in vivo long-term (>20 days) stability. Successful radio-labeling and in vivo stability are demonstrated to be highly dependent on both the concentration and location of deprotonated silanol groups (−Si–O–) from two types of silica nanoparticles investigated. This work reports 89Zr-labeled MSN with a detailed labeling mechanism investigation and long-term stability study. With its attractive radio-stability and the simplicity of chelator-free radio-labeling, 89Zr-MSN offers a novel, simple, and accurate way for studying the in vivo long-term fate and PET image-guided drug delivery of MSN in the near future. PMID:26213260

  20. Preparation, characterization and FE-simulation of the reinforcement of polycaprolactone with PEGylated silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Moussaif, N.; Viejo, I.; Bielsa, J. M.; Crespo, C.; Irusta, S.; Yagüe, C.; Meier, J. G.

    2012-09-01

    We recently published the preparation and characterization of polycaprolactone (PCL) nanocomposites with a 45% increased modulus reinforced with only 4 wt% PEGylated silica (polyethylene-glycol/SiO2) nanoparticles obtained by melt-extrusion [1]. The achieved reinforcement is related to an excellent dispersion of the nanoparticles due to the polyethylene-glycol graft of the nanoparticles which was obtained by a simple one-pot synthesis. X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FTIR) analyses identified the location of the PEG at the PCL/silica interface. However, the extension of the interface could not be resolved. In an attempt to describe the effect of the interface on the reinforcement we applied several analytical micromechanical models. Models considering core-shell systems fitted the experimental data well and gave estimations of the modulus and extension of the interphase. However, different sets of parameters gave equally good representations. In an alternative approach, 3D representative volume elements (RVE) of the composite with spherical nanoparticles including the shell were built-up from the morphological data to carry out computational micromechanics based on finite elements (FE). The interphase was modeled in the RVE. Both approaches demonstrated the need of an interphase extension of roughly twice the radius of the particle. The FEM approach estimates the interface-modulus much higher than the analytical models.

  1. Synthesis of Biomolecule-Modified Mesoporous Silica Nanoparticles for Targeted Hydrophobic Drug Delivery to Cancer Cells

    PubMed Central

    Ferris, Daniel P.; Lu, Jie; Gothard, Chris; Yanes, Rolando; Thomas, Courtney R.; Olsen, John-Carl; Stoddart, J. Fraser; Tamanoi, Fuyuhiko; Zink, Jeffrey I.

    2011-01-01

    Synthetic methodologies integrating hydrophobic drug delivery and biomolecular targeting with mesoporous silica nanoparticles are described. Transferrin and cyclic-RGD peptides are covalently attached to the nanoparticles utilizing different techniques and provide selectivity between primary and metastatic cancer cells. The increase in cellular uptake of the targeted particles is examined using fluorescence microscopy and flow cytometry. Transferrin-modified silica nanoparticles display enhancement in particle uptake by Panc-1 cancer cells over that of normal HFF cells. The endocytotic pathway for these particles is further investigated through plasmid transfection of the transferrin receptor into the normal HFF cell line, which results in an increase in particle endocytosis as compared to unmodified HFF cells. By designing and attaching a synthetic cyclic-RGD, selectivity between primary cancer cells (BT-549) and metastatic cancer cells (MDA-MB 435) is achieved with enhanced particle uptake by the metastatic cancer cell line. Incorporation of the hydrophobic drug Camptothecin into these two types of biomolecular-targeted nanoparticles causes an increase in mortality of the targeted cancer cells compared to that caused by both the free drug and nontargeted particles. These results demonstrate successful biomolecular-targeted hydrophobic drug delivery carriers that selectively target specific cancer cells and result in enhanced drug delivery and cell mortality. PMID:21595023

  2. Rheological Properties of Nanoparticle Silica-Surfactant Stabilized Crude Oil Emulsions: Influence of Temperature, Nanoparticle Concentration and Water Volume Fraction"

    NASA Astrophysics Data System (ADS)

    Kinsey, Erin; Pales, Ashley; Li, Chunyan; Mu, Linlin; Bai, Lingyun; Clifford, Heather; Darnault, Christophe

    2016-04-01

    Oil in water emulsions occur during oil extraction due to the presence of water, naturally-occurring surface-active agents and mechanical mixing in pipelines or from oil spillage. Emulsions present difficulties for use of oil in fuel and their rheological properties are important to treat environmental impacts of spills. The objective of this study is to assess the rheological characteristics of oil in water emulsions stabilized by 5% NaCl brine, Tween 20 surfactant and silica nanoparticles to gain knowledge about the behavior of oil flow in pipelines and characterize them for environmental applications. Rheological behaviors such as shear rate, shear stress, and viscosity of Prudhoe Bay crude oil emulsions were analyzed with varying percent of water volume fractions (12.5, 25 and 50%), varying weight percent of silica nanoparticles (0.001, 0.01 and 0.1 weight %), with and without 2 CMC Tween 20 nonionic surfactant. Emulsions with varying water volume fractions were analyzed at 20, 40 and 60 degrees Celsius. Flow curve analysis of the emulsions was performed using an Anton-Paar rheometer. Preliminary findings indicate that increased temperature and increasing the concentration of nanoparticles both produced lower shear stress and that the addition of surfactant decreased the viscosity and shear stress of the emulsions.

  3. Functionalized Fe3O4@silica core-shell nanoparticles as microalgae harvester and catalyst for biodiesel production.

    PubMed

    Chiang, Ya-Dong; Dutta, Saikat; Chen, Ching-Tien; Huang, Yu-Tzu; Lin, Kuen-Song; Wu, Jeffrey C S; Suzuki, Norihiro; Yamauchi, Yusuke; Wu, Kevin C-W

    2015-03-01

    Core-shell Fe3O4@silica magnetic nanoparticles functionalized with a strong base, triazabicyclodecene (TBD), were successfully synthesized for harvesting microalgae and for one-pot microalgae-to-fatty acid methyl ester (FAME, or so-called biodiesel) conversion. Three types of algae oil sources (i.e., dried algae, algae oil, and algae concentrate) were used and the reaction conditions were optimized to achieve the maximum biodiesel yield. The results obtained in this study show that our TBD-functionalized Fe3O4@silica nanoparticles could effectively convert algae oil to biodiesel with a maximum yield of 97.1 %. Additionally, TBD-Fe3O4@silica nanoparticles act as an efficient algae harvester because of their adsorption and magnetic properties. The method presented in this study demonstrates the wide scope for the use of covalently functionalized core-shell nanoparticles for the production of liquid transportation fuels from algal biomass. PMID:25477296

  4. The development of a silica nanoparticle-based label-free DNA biosensor

    NASA Astrophysics Data System (ADS)

    Kell, Arnold J.; Pagé, Lilianne; Tan, Sophie; Charlebois, Isabelle; Boissinot, Maurice; Leclerc, Mario; Simard, Benoit

    2011-09-01

    A silica nanoparticle-based DNA biosensor capable of detecting Bacillus anthracis bacteria through the use of unlabelled ss-oligonucleotides has been developed. The biosensor makes use of the optical changes that accompany a nanoparticle-immobilized cationic conjugated polymer (polythiophene) interacting with single-stranded vs. hybridized oligonucleotides, where a fluorescence signal appears only when hybridized DNA is present (i.e. only when the ss-oligonucleotide interacting with the polymer has hybridized with its complement). In order to enhance the sensitivity of the biosensor, two different nanoparticle architectures were developed and used to elucidate how the presence of neighboring fluorophores on the nanoparticle surface affects Förster-resonant energy transfer (FRET) between the polythiophene/oligonucleotide complex (FRET donor) and the fluorophores (FRET acceptors). We demonstrate that the silica nanoparticle-based FRET platform lowers the limit of detection at least 10-fold in comparison to the polythiophene itself, and allows the detection of ~2 × 10-12 moles of ss-oligonucleotide in a 100 μL sample with a standard fluorimeter (i.e. has a limit of detection of ~2 nM ssDNA). Such nanoparticle-based biosensor platforms are beneficial because of the robustness and stability inherent to their covalent assembly and they provide a valuable new tool that may allow for the sensitive, label-free detection (the target DNA that produces the fluorescence signal is unlabelled) without the use of polymerase chain reaction.A silica nanoparticle-based DNA biosensor capable of detecting Bacillus anthracis bacteria through the use of unlabelled ss-oligonucleotides has been developed. The biosensor makes use of the optical changes that accompany a nanoparticle-immobilized cationic conjugated polymer (polythiophene) interacting with single-stranded vs. hybridized oligonucleotides, where a fluorescence signal appears only when hybridized DNA is present (i.e. only when

  5. Durable superhydrophobic and antireflective surfaces by trimethylsilanized silica nanoparticles-based sol-gel processing.

    PubMed

    Manca, Michele; Cannavale, Alessandro; De Marco, Luisa; Aricò, Antonino S; Cingolani, Roberto; Gigli, Giuseppe

    2009-06-01

    We present a robust and cost-effective coating method to fabricate long-term durable superhydrophobic andsimultaneouslyantireflective surfaces by a double-layer coating comprising trimethylsiloxane (TMS) surface-functionalized silica nanoparticles partially embedded into an organosilica binder matrix produced through a sol-gel process. A dense and homogeneous organosilica gel layer was first coated onto a glass substrate, and then, a trimethylsilanized nanospheres-based superhydrophobic layer was deposited onto it. After thermal curing, the two layers turned into a monolithic film, and the hydrophobic nanoparticles were permanently fixed to the glass substrate. Such treated surfaces showed a tremendous water repellency (contact angle = 168 degrees ) and stable self-cleaning effect during 2000 h of outdoor exposure. Besides this, nanotextured topology generated by the self-assembled nanoparticles-based top layer produced a fair antireflection effect consisting of more than a 3% increase in optical transmittance. PMID:19466786

  6. Dynamics at the Polymer/Nanoparticle Interface in Poly(2-vinylpyridine)/Silica Nanocomposites.

    SciTech Connect

    Holt, Adam P; Griffin, Phillip; Bocharova, Vera; Agapov, Alexander L; Imel, Adam E; Dadmun, Mark D; Sangoro, Joshua R; Sokolov, Alexei P

    2014-01-01

    The static and dynamic properties of poly(2-vinylpyridine)/silica nanocomposites are investigated by temperature modulated differential scanning calorimetry, broadband dielectric spectroscopy (BDS), small-angle X-ray scattering (SAXS), and transmission electron microscopy. Both BDS and SAXS detect the existence of an interfacial polymer layer on the surface of nanoparticles. The results show that whereas the calorimetric glass transition temperature varies only weakly with nanoparticle loading, the segmental mobility of the polymer interfacial layer is slower than the bulk polymer by 2 orders of magnitude. Detailed analysis of BDS and SAXS data reveal that the interfacial layer has a thickness of 4 6 nm irrespective of the nanoparticle concentration. These results demonstrate that in contrast to some recent articles on polymer nanocomposites, the interfacial polymer layer is by no means a dead layer . However, its existence might provide some explanation for controversies surrounding the dynamics of polymer nanocomposites.

  7. Broadband tunability of surface plasmon resonance in graphene-coating silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhe, Shi; Yang, Yang; Lin, Gan; Zhi-Yuan, Li

    2016-05-01

    Graphene decorated nanomaterials and nanostructures can potentially be used in military and medical science applications. In this article, we study the optical properties of a graphene wrapping silica core–shell spherical nanoparticle under illumination of external light by using the Mie theory. We find that the nanoparticle can exhibit surface plasmon resonance (SPR) that can be broadly tuned from mid infrared to near infrared via simply changing the geometric parameters. A simplified equivalent dielectric permittivity model is developed to better understand the physics of SPR, and the calculation results agree well qualitatively with the rigorous Mie theory. Both calculations suggest that a small radius of graphene wrapping nanoparticle with high Fermi level could move the SPR wavelength of graphene into the near infrared regime. Project supported by the National Natural Science Foundation of China (Grant Nos. 11204365 and 11434017) and the National Basic Research Program of China (Grant No. 2013CB632704).

  8. Size-dependent interaction of silica nanoparticles with lysozyme and bovine serum albumin proteins

    NASA Astrophysics Data System (ADS)

    Yadav, Indresh; Aswal, Vinod K.; Kohlbrecher, Joachim

    2016-05-01

    The interaction of three different sized (diameter 10, 18, and 28 nm) anionic silica nanoparticles with two model proteins—cationic lysozyme [molecular weight (MW) 14.7 kDa)] and anionic bovine serum albumin (BSA) (MW 66.4 kDa) has been studied by UV-vis spectroscopy, dynamic light scattering (DLS), and small-angle neutron scattering (SANS). The adsorption behavior of proteins on the nanoparticles, measured by UV-vis spectroscopy, is found to be very different for lysozyme and BSA. Lysozyme adsorbs strongly on the nanoparticles and shows exponential behavior as a function of lysozyme concentration irrespective of the nanoparticle size. The total amount of adsorbed lysozyme, as governed by the surface-to-volume ratio, increases on lowering the size of the nanoparticles for a fixed volume fraction of the nanoparticles. On the other hand, BSA does not show any adsorption for all the different sizes of the nanoparticles. Despite having different interactions, both proteins induce similar phase behavior where the nanoparticle-protein system transforms from one phase (clear) to two phase (turbid) as a function of protein concentration. The phase behavior is modified towards the lower concentrations for both proteins with increasing the nanoparticle size. DLS suggests that the phase behavior arises as a result of the nanoparticles' aggregation on the addition of proteins. The size-dependent modifications in the interaction potential, responsible for the phase behavior, have been determined by SANS data as modeled using the two-Yukawa potential accounting for the repulsive and attractive interactions in the systems. The protein-induced interaction between the nanoparticles is found to be short-range attraction for lysozyme and long-range attraction for BSA. The magnitude of attractive interaction irrespective of protein type is enhanced with increase in the size of the nanoparticles. The total (attractive+repulsive) potential leading to two-phase formation is found to be

  9. Size-dependent interaction of silica nanoparticles with lysozyme and bovine serum albumin proteins.

    PubMed

    Yadav, Indresh; Aswal, Vinod K; Kohlbrecher, Joachim

    2016-05-01

    The interaction of three different sized (diameter 10, 18, and 28 nm) anionic silica nanoparticles with two model proteins-cationic lysozyme [molecular weight (MW) 14.7 kDa)] and anionic bovine serum albumin (BSA) (MW 66.4 kDa) has been studied by UV-vis spectroscopy, dynamic light scattering (DLS), and small-angle neutron scattering (SANS). The adsorption behavior of proteins on the nanoparticles, measured by UV-vis spectroscopy, is found to be very different for lysozyme and BSA. Lysozyme adsorbs strongly on the nanoparticles and shows exponential behavior as a function of lysozyme concentration irrespective of the nanoparticle size. The total amount of adsorbed lysozyme, as governed by the surface-to-volume ratio, increases on lowering the size of the nanoparticles for a fixed volume fraction of the nanoparticles. On the other hand, BSA does not show any adsorption for all the different sizes of the nanoparticles. Despite having different interactions, both proteins induce similar phase behavior where the nanoparticle-protein system transforms from one phase (clear) to two phase (turbid) as a function of protein concentration. The phase behavior is modified towards the lower concentrations for both proteins with increasing the nanoparticle size. DLS suggests that the phase behavior arises as a result of the nanoparticles' aggregation on the addition of proteins. The size-dependent modifications in the interaction potential, responsible for the phase behavior, have been determined by SANS data as modeled using the two-Yukawa potential accounting for the repulsive and attractive interactions in the systems. The protein-induced interaction between the nanoparticles is found to be short-range attraction for lysozyme and long-range attraction for BSA. The magnitude of attractive interaction irrespective of protein type is enhanced with increase in the size of the nanoparticles. The total (attractive+repulsive) potential leading to two-phase formation is found to be

  10. Immune response to functionalized mesoporous silica nanoparticles for targeted drug delivery

    NASA Astrophysics Data System (ADS)

    Heidegger, Simon; Gößl, Dorothée; Schmidt, Alexandra; Niedermayer, Stefan; Argyo, Christian; Endres, Stefan; Bein, Thomas; Bourquin, Carole

    2015-12-01

    Multifunctional mesoporous silica nanoparticles (MSN) have attracted substantial attention with regard to their high potential for targeted drug delivery. For future clinical applications it is crucial to address safety concerns and understand the potential immunotoxicity of these nanoparticles. In this study, we assess the biocompatibility and functionality of multifunctional MSN in freshly isolated, primary murine immune cells. We show that the functionalized silica nanoparticles are rapidly and efficiently taken up into the endosomal compartment by specialized antigen-presenting cells such as dendritic cells. The silica nanoparticles showed a favorable toxicity profile and did not affect the viability of primary immune cells from the spleen in relevant concentrations. Cargo-free MSN induced only very low immune responses in primary cells as determined by surface expression of activation markers and release of pro-inflammatory cytokines such as Interleukin-6, -12 and -1β. In contrast, when surface-functionalized MSN with a pH-responsive polymer capping were loaded with an immune-activating drug, the synthetic Toll-like receptor 7 agonist R848, a strong immune response was provoked. We thus demonstrate that MSN represent an efficient drug delivery vehicle to primary immune cells that is both non-toxic and non-inflammagenic, which is a prerequisite for the use of these particles in biomedical applications.Multifunctional mesoporous silica nanoparticles (MSN) have attracted substantial attention with regard to their high potential for targeted drug delivery. For future clinical applications it is crucial to address safety concerns and understand the potential immunotoxicity of these nanoparticles. In this study, we assess the biocompatibility and functionality of multifunctional MSN in freshly isolated, primary murine immune cells. We show that the functionalized silica nanoparticles are rapidly and efficiently taken up into the endosomal compartment by specialized

  11. Microwave-induced synthesis of highly dispersed gold nanoparticles within the pore channels of mesoporous silica

    SciTech Connect

    Gu Jinlou; Fan Wei; Shimojima, Atsushi; Okubo, Tatsuya

    2008-04-15

    Highly dispersed gold nanoparticles have been incorporated into the pore channels of SBA-15 mesoporous silica through a newly developed strategy assisted by microwave radiation (MR). The sizes of gold are effectively controlled attributed to the rapid and homogeneous nucleation, simultaneous propagation and termination of gold precursor by MR. Diol moieties with high dielectric and dielectric loss constants, and hence a high microwave activation, were firstly introduced to the pore channels of SBA-15 by a simple addition reaction between amino group and glycidiol and subsequently served as the reduction centers for gold nanoparticles. Extraction of the entrapped gold from the nanocomposite resulted in milligram quantities of gold nanoparticles with low dispersity. The successful assembly process of diol groups and formation of gold nanoparticles were monitored and tracked by solid-state NMR and UV-vis measurements. Characterization by small angle X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the incorporation of gold nanoparticles would not breakup the structural integrity and long-range periodicity of SBA-15. The gold nanoparticles had a narrow size distribution with diameters in the size range of 5-10 nm through TEM observation. The average particles size is 7.9 nm via calculation by the Scherrer formula and TEM measurements. Nitrogen adsorption and desorption isotherms gave further evidence that the employed method was efficient and gold nanoparticles were successfully incorporated into the pore channels of SBA-15. - Graphical abstract: A facile and novel strategy has been developed to incorporate gold nanoparticles into the pore channels of mesoporous SBA-15 assisted by microwave radiation (MR) with mild reaction condition and rapid reaction speed. Due to the rapid and homogeneous nucleation, simultaneous propagation and termination by MR, the size of gold nanoparticles are effectively controlled.

  12. Interactions of silica nanoparticles with therapeutics for oxidative stress attenuation in neurons

    NASA Astrophysics Data System (ADS)

    White-Schenk, Desiree; Shi, Riyi; Leary, James F.

    2015-03-01

    Oxidative stress plays a major role in many disease pathologies, notably in the central nervous system (CNS). For instance, after initial spinal cord injury, the injury site tends to increase during a secondary chemical injury process based on oxidative stress from necrotic cells and the inflammatory response. Prevention of this secondary chemical injury would represent a major advance in the treatment of people with spinal cord injuries. Few therapeutics are useful in combating such stress in the CNS due to side effects, low efficacy, or half-life. Mesoporous silica nanoparticles show promise for delivering therapeutics based on the formation of a porous network during synthesis. Ideally, they increase the circulation time of loaded therapeutics to increase the half-life while reducing overall concentrations to avoid side effects. The current study explored the use of silica nanoparticles for therapeutic delivery of anti-oxidants, in particular, the neutralization of acrolein which can lead to extensive tissue damage due to its ability to generate more and more copies of itself when it interacts with normal tissue. Both an FDA-approved therapeutic, hydralazine, and natural product, epigallocatechin gallate, were explored as antioxidants for acrolein with nanoparticles for increased efficacy and stability in neuronal cell cultures. Not only were the nanoparticles explored in neuronal cells, but also in a co-cultured in vitro model with microglial cells to study potential immune responses to near-infrared (NIRF)-labeled nanoparticles and uptake. Studies included nanoparticle toxicity, uptake, and therapeutic response using fluorescence-based techniques with both dormant and activated immune microglia co-cultured with neuronal cells.

  13. Biosafety evaluations of well-dispersed mesoporous silica nanoparticles: towards in vivo-relevant conditions

    NASA Astrophysics Data System (ADS)

    Liu, Tsang-Pai; Wu, Si-Han; Chen, Yi-Ping; Chou, Chih-Ming; Chen, Chien-Tsu

    2015-04-01

    This study aimed to investigate how mesoporous silica nanoparticles (MSNs), especially focussing on their surface functional groups, interacted with Raw 264.7 macrophages, as well as with zebrafish embryos. Upon introducing nanoparticles into a biological milieu, adsorption of proteins and biomolecules onto the nanoparticle surface usually progresses rapidly. Nanoparticles bound with proteins can result in physiological and pathological changes, but the mechanisms remain to be elucidated. In order to evaluate how protein corona affected MSNs and the subsequent cellular immune responses, we experimented in both serum and serum-deprived conditions. Our findings indicated that the level of p-p38 was significantly elevated by the positively charged MSNs, whereas negatively charged MSNs resulted in marked ROS production. Most significantly, our experiments demonstrated that the presence of protein efficiently mitigated the potential nano-hazard. On the other hand, strongly positively charged MSNs caused 94% of the zebrafish embryos to die. In that case, the toxicity caused by the quaternary ammonium ligands on the surface of those nanoparticles was exerted in a dose-dependent manner. In summary, these fundamental studies here provide valuable insights into the design of better biocompatible nanomaterials in the future.This study aimed to investigate how mesoporous silica nanoparticles (MSNs), especially focussing on their surface functional groups, interacted with Raw 264.7 macrophages, as well as with zebrafish embryos. Upon introducing nanoparticles into a biological milieu, adsorption of proteins and biomolecules onto the nanoparticle surface usually progresses rapidly. Nanoparticles bound with proteins can result in physiological and pathological changes, but the mechanisms remain to be elucidated. In order to evaluate how protein corona affected MSNs and the subsequent cellular immune responses, we experimented in both serum and serum-deprived conditions. Our

  14. Size and ζ-Potential Measurement of Silica Nanoparticles in Serum Using Tunable Resistive Pulse Sensing.

    PubMed

    Sikora, Aneta; Shard, Alexander G; Minelli, Caterina

    2016-03-01

    The contact of nanoparticles with biological fluids such as serum results in rapid adsorption of proteins at the nanoparticle surface in a layer known as the "protein corona". Protein coatings modify and control the behavior of the nanoparticles potentially altering the aggregation state and cellular response, which may influence their fate and hazard to human health. Cells are likely to interact with the protein interface rather than with bare surface; therefore it is important to study the protein layer and develop appropriate measurement tools. In this study we investigate how adsorbed proteins from serum affect the size and the surface charge of plain and aminated silica nanoparticles. Particle size and size distributions in buffer and serum-based biological media were studied using tunable resistive pulse sensing (TRPS), as well as differential centrifugal sedimentation (DCS) and dynamic light scattering (DLS). Average and single particle ζ-potentials (related to surface charge) were also measured by electrophoretic light scattering (ELS) and TRPS, respectively. Size measurements showed an increase in size of the nanoparticles upon acquisition of a protein layer, thus allowing an estimation of its thickness. DLS proved incapable of providing an accurate measurement of the nanoparticles' size in serum due to the presence of agglomerates. The ability of TRPS to measure sample agglomeration was investigated by comparison with the high resolution technique of DCS. Particle-by-particle ζ-potential measurements by TRPS were consistent with those performed with ELS and allowed a description of the ζ-potential distribution within the samples. PMID:26869024

  15. Direct imaging Au nanoparticle migration inside mesoporous silica channels.

    PubMed

    Liu, Zhengwang; Che, Renchao; Elzatahry, Ahmed A; Zhao, Dongyuan

    2014-10-28

    Supported metal nanoparticle (NP) catalysts have been widely used in many industry processes and catalytic reactions. Catalyst deactivation is mainly caused by the sintering of supported metal NPs. Hence, understanding the metal NPs' sintering behaviors has great significance in preventing catalyst deactivation. Here we report the metal particle migration inside/between mesochannels by scanning transmission electron microscopy and electron energy loss spectroscopy via an in situ TEM heating technique. A sintering process is proposed that particle migration predominates, driven by the difference of gravitational potential from the height of the uneven internal surface of the mesopores; when the distance of the gold nanoparticles with a size of about 3 and 5 nm becomes short after migration, the coalescence process is completed, which is driven by an "octopus-claw-like" expansion of a conduction electron cloud outside the Au NPs. The supports containing an abundance of micropores help to suppress particle migration and coalescence. Our findings provide the understanding toward the rational design of supported industrial catalysts and other nanocomposites with enhanced activity and stability for applications such as batteries, catalysis, drug delivery, gas sensors, and solar cells. PMID:25264601

  16. Electrochemical Properties of Carbon Nanoparticles Entrapped in Silica Matrix

    PubMed Central

    Bok, Sangho; Lubguban, Arnold A.; Gao, Yuanfang; Bhattacharya, Shantanu; Korampally, Venu; Hossain, Maruf; Gillis, Kevin D.; Gangopadhyay, Shubhra

    2008-01-01

    Carbon-based electrode materials have been widely used for many years for electrochemical charge storage, energy generation, and catalysis. We have developed an electrode material with high specific capacitance by entrapping graphite nanoparticles into a sol-gel network. Films from the resulting colloidal suspensions were highly porous due to the removal of the entrapped organic solvents from sol-gel matrix giving rise to high Brunauer-Emmett-Teller (BET) specific surface areas (654 m2/g) and a high capacitance density (∼37 F/g). An exponential increase of capacitance was observed with decreasing scan rates in cyclic voltammetry studies on these films suggesting the presence of pores ranging from micro (< 2 nm) to mesopores. BET surface analysis and scanning electron microscope images of these films also confirmed the presence of the micropores as well as mesopores. A steep drop in the double layer capacitance with polar electrolytes was observed when the films were rendered hydrophilic upon exposure to a mild oxygen plasma. We propose a model whereby the microporous hydrophobic sol-gel matrix perturbs the hydration of ions which moves ions closer to the graphite nanoparticles and consequently increase the capacitance of the film. PMID:18953420

  17. Amorphous silica nanoparticles trigger nitric oxide/peroxynitrite imbalance in human endothelial cells: inflammatory and cytotoxic effects

    PubMed Central

    Corbalan, J Jose; Medina, Carlos; Jacoby, Adam; Malinski, Tadeusz; Radomski, Marek W

    2011-01-01

    Background The purpose of this study was to investigate the mechanism of noxious effects of amorphous silica nanoparticles on human endothelial cells. Methods Nanoparticle uptake was examined by transmission electron microscopy. Electrochemical nanosensors were used to measure the nitric oxide (NO) and peroxynitrite (ONOO−) released by a single cell upon nanoparticle stimulation. The downstream inflammatory effects were measured by an enzyme-linked immunosorbent assay, real-time quantitative polymerase chain reaction, and flow cytometry, and cytotoxicity was measured by lactate dehydrogenase assay. Results We found that the silica nanoparticles penetrated the plasma membrane and rapidly stimulated release of cytoprotective NO and, to a greater extent, production of cytotoxic ONOO−. The low [NO]/[ONOO−] ratio indicated increased nitroxidative/oxidative stress and correlated closely with endothelial inflammation and necrosis. This imbalance was associated with nuclear factor κB activation, upregulation of key inflammatory factors, and cell death. These effects were observed in a nanoparticle size-dependent and concentration-dependent manner. Conclusion The [NO]/[ONOO−] imbalance induced by amorphous silica nanoparticles indicates a potentially deleterious effect of silica nanoparticles on vascular endothelium. PMID:22131828

  18. Preparation and Characterization of Rifampin Loaded Mesoporous Silica Nanoparticles as a Potential System for Pulmonary Drug Delivery

    PubMed Central

    Mohseni, Meysam; Gilani, Kambiz; Mortazavi, Seyed Alireza

    2015-01-01

    The goal of this research is to determine the feasibility of loading rifampin into mesoporous silica nanoparticles. Rifampin was selected as a model lipophilic molecule since it is a well-documented and much used anti tuberculosis drug. The mesoporous silica nanoparticles were prepared by using tetraethyl ortho silicate and cetyltrimethyl ammonium bromide (as surfactant). The prepared nanoparticles were characterized in terms of their particle size measurement and porosimetry. The results showed that the particle size is 218 ± 46 nm (mean ± SD) and surface area is 816 m2g-1. In order to load rifampin within the mesopores, adsorption experiments using three different solvents (methanol, water and dimethyl sulfoxide) were carried out. The loading procedure resulted in a significant improvement in the amount of rifampin loaded into mesoporous silica nanoparticles and methanol was found to be a suitable solvent, providing a drug entrapment efficiency of 52 %. Rifampin loaded nanoparticles underwent different in-vitro tests including, SEM and drug release. The in-vitro drug release was investigated using buffer phosphate (pH=7.4). Regarding the drug release study, a biphasic pattern of release was observed. The drug-loaded mesoporous silica nanoparticles were capable of releasing 95% of their drug content after 24 h, following a faster release in the first four hours. The prepared rifampin loaded nanoparticles seem to have potential for use as a pulmonary drug delivery. PMID:25561909

  19. Synthesis of amino-rich silica-coated magnetic nanoparticles for the efficient capture of DNA for PCR.

    PubMed

    Bai, Yalong; Cui, Yan; Paoli, George C; Shi, Chunlei; Wang, Dapeng; Zhou, Min; Zhang, Lida; Shi, Xianming

    2016-09-01

    Magnetic separation has great advantages over traditional bio-separation methods and has become popular in the development of methods for the detection of bacterial pathogens, viruses, and transgenic crops. Functionalization of magnetic nanoparticles is a key factor for efficient capture of the target analytes. In this paper, we report the synthesis of amino-rich silica-coated magnetic nanoparticles using a one-pot method. This type of magnetic nanoparticle has a rough surface and a higher density of amino groups than the nanoparticles prepared by a post-modification method. Furthermore, the results of hydrochloric acid treatment indicated that the magnetic nanoparticles were stably coated. The developed amino-rich silica-coated magnetic nanoparticles were used to directly adsorb DNA. After magnetic separation and blocking, the magnetic nanoparticles and DNA complexes were used directly for the polymerase chain reaction (PCR), without onerous and time-consuming purification and elution steps. The results of real-time quantitative PCR showed that the nanoparticles with higher amino group density resulted in improved DNA capture efficiency. The results suggest that amino-rich silica-coated magnetic nanoparticles are of great potential for efficient bio-separation of DNA prior to detection by PCR. PMID:27187190

  20. Solid-State NMR Characterization of Mixed Phosphonic Acid Ligand Binding and Organization on Silica Nanoparticles.

    PubMed

    Davidowski, Stephen K; Holland, Gregory P

    2016-04-01

    As ligand functionalization of nanomaterials becomes more complex, methods to characterize the organization of multiple ligands on surfaces is required. In an effort to further the understanding of ligand-surface interactions, a combination of multinuclear ((1)H, (29)Si, (31)P) and multidimensional solid-state nuclear magnetic resonance (NMR) techniques was utilized to characterize the phosphonic acid functionalization of fumed silica nanoparticles using methylphosphonic acid (MPA) and phenylphosphonic acid (PPA). (1)H → (29)Si cross-polarization (CP)-magic angle spinning (MAS) solid-state NMR was used to selectively detect silicon atoms near hydrogen atoms (primarily surface species); these results indicate that geminal silanols are preferentially depleted during the functionalization with phosphonic acids. (1)H → (31)P CP-MAS solid-state NMR measurements on the functionalized silica nanoparticles show three distinct resonances shifted upfield (lower ppm) and broadened compared to the resonances of the crystalline ligands. Quantitative (31)P MAS solid-state NMR measurements indicate that ligands favor a monodentate binding mode. When fumed silica nanoparticles were functionalized with an equal molar ratio of MPA and PPA, the MPA bound the nanoparticle surface preferentially. Cross-peaks apparent in the 2D (1)H exchange spectroscopy (EXSY) NMR measurements of the multiligand sample at short mixing times indicate that the MPA and PPA are spatially close (≤5 Å) on the surface of the nanostructure. Furthermore, (1)H-(1)H double quantum-single quantum (DQ-SQ) back-to-back (BABA) 2D NMR spectra further confirmed that MPA and PPA are strongly dipolar coupled with observation of DQ intermolecular contacts between the ligands. DQ experimental buildup curves and simulations indicate that the average distance between MPA and PPA is no further than 4.2 ± 0.2 Å. PMID:26914738

  1. Magnetite-containing spherical silica nanoparticles for biocatalysis and bioseparations.

    PubMed

    Yang, Huang-Hao; Zhang, Shu-Qiong; Chen, Xiao-Lan; Zhuang, Zhi-Xia; Xu, Jin-Gou; Wang, Xiao-Ru

    2004-03-01

    The simultaneous entrapment of biological macromolecules and nanostructured silica-coated magnetite in sol-gel materials using a reverse-micelle technique leads to a bioactive, mechanically stable, nanometer-sized, and magnetically separable particles. These spherical particles have a typical diameter of 53 +/- 4 nm, a large surface area of 330 m(2)/g, an average pore diameter of 1.5 nm, a total pore volume of 1.427 cm(3)/g and a saturated magnetization (M(S)) of 3.2 emu/g. Peroxidase entrapped in these particles shows Michaelis-Mentan kinetics and high activity. The catalytic reaction will take place immediately after adding these particles to the reaction solution. These enzyme entrapping particles catalysts can be easily separated from the reaction mixture by simply using an external magnetic field. Experiments have proved that these catalysts have a long-term stability toward temperature and pH change, as compared to free enzyme molecules. To further prove the application of this novel magnetic biomaterial in analytical chemistry, a magnetic-separation immunoassay system was also developed for the quantitative determination of gentamicin. The calibration for gentamicin has a working range of 200-4000 ng/mL, with a detection limit of 160 ng/mL, which is close to that of the fluorescent polarization immunoassay (FPIA) using the same reactants. PMID:14987087

  2. Bioprobes Based on Aptamer and Silica Fluorescent Nanoparticles for Bacteria Salmonella typhimurium Detection

    NASA Astrophysics Data System (ADS)

    Wang, Qiu-Yue; Kang, Yan-Jun

    2016-03-01

    In this study, we have developed an efficient method based on single-stranded DNA (ssDNA) aptamers along with silica fluorescence nanoparticles for bacteria Salmonella typhimurium detection. Carboxyl-modified Tris(2,2'-bipyridyl)dichlororuthenium(II) hexahydrate (RuBPY)-doped silica nanoparticles (COOH-FSiNPs) were prepared using reverse microemulsion method, and the streptavidin was conjugated to the surface of the prepared COOH-FSiNPs. The bacteria S. typhimurium was incubated with a specific ssDNA biotin-labeled aptamer, and then the aptamer-bacteria conjugates were treated with the synthetic streptavidin-conjugated silica fluorescence nanoprobes (SA-FSiNPs). The results under fluorescence microscopy show that SA-FSiNPs can be applied effectively for the labeling of bacteria S. typhimurium with great photostable property. To further verify the specificity of SA-FSiNPs out of multiple bacterial conditions, variant concentrations of bacteria mixtures composed of bacteria S. typhimurium, Escherichia coli, and Bacillus subtilis were treated with SA-FSiNPs.

  3. A silica optical fiber doped with yttrium aluminosilicate nanoparticles for supercontinuum generation

    NASA Astrophysics Data System (ADS)

    Cheng, Tonglei; Liao, Meisong; Xue, Xiaojie; Li, Jiang; Gao, Weiqing; Li, Xia; Chen, Danping; Zheng, Shupei; Pan, Yubai; Suzuki, Takenobu; Ohishi, Yasutake

    2016-03-01

    We design and fabricate a silica optical fiber doped with yttrium aluminosilicate (YAS, Y2O3-Al2O3-SiO2) nanoparticles in the core. The optical fiber is drawn directly from a silica tube with YAG (Y3Al5O12) ceramics and silica powders (the molar ratio 1:18) in the core at the temperature of ∼1950 °C. The YAS nanoparticles are formed during the optical fiber drawing process. Supercontinuum (SC) generation in the optical fiber is investigated at different pump wavelength. At the pump wavelength of ∼1750 nm which is in the deep anomalous dispersion region, SC spectrum evolution is mainly due to multiple solitons and dispersive waves (DWs), and three pairs of multiple optical solitons and DWs are observed. When the pump wavelength shifts to ∼1500 nm which is close to the zero-dispersion wavelength (ZDW), flattened SC spectrum with ±7 dB uniformity is obtained at the wavelength region of ∼990-1980 nm, and only one obvious soliton and DW are observed. At the pump wavelength of ∼1100 nm, a narrow SC spectrum from ∼1020 to 1180 nm is obtained in the normal dispersion region due to self-phase modulation (SPM) effect.

  4. Optimization of protocell of silica nanoparticles using 3² factorial designs.

    PubMed

    Kaur, Gunjeet; Rath, Goutam; Heer, Hemraj; Goyal, Amit K

    2012-03-01

    The purpose of the research is to carry out systemic optimization of protocells (liposomes entrapped with silica particles). Optimization was carried out using 3(2) factorial designs for the selection of the optimized protocell composition with reference to particle size distribution and zetapotential. This design was carried out to study the effect of independent variables such as molar ratio of phosphatidylcholine to cholesterol and concentration of silica nanoparticles. A total of nine formulations of protocells were prepared and analyzed using Design expert® software from Stat-Ease, Inc. (Version 8.0.4.1 trial 2010) for the selection of the optimized combination. Contour plots were constructed with independent variables like size and potential. Protocell with 7:3 ratio of phosphatidyl choline to cholesterol and 0.5 mg/ml of silica nanoparticles demonstrated better colloidal behaviors. The findings obtained from the software corresponding to independent variables demonstrated accurate means for the optimization of the pharmaceutical formulations. PMID:22173376

  5. Protocells: Modular Mesoporous Silica Nanoparticle-Supported Lipid Bilayers for Drug Delivery.

    PubMed

    Butler, Kimberly S; Durfee, Paul N; Theron, Christophe; Ashley, Carlee E; Carnes, Eric C; Brinker, C Jeffrey

    2016-04-27

    Mesoporous silica nanoparticle-supported lipid bilayers, termed 'protocells,' represent a potentially transformative class of therapeutic and theranostic delivery vehicle. The field of targeted drug delivery poses considerable challenges that cannot be addressed with a single 'magic bullet'. Consequently, the protocell has been designed as a modular platform composed of interchangeable biocompatible components. The mesoporous silica core has variable size and shape to direct biodistribution and a controlled pore size and surface chemistry to accommodate diverse cargo. The encapsulating supported lipid bilayer can be modified with targeting and trafficking ligands as well as polyethylene glycol (PEG) to effect selective binding, endosomal escape of cargo, drug efflux prevention, and potent therapeutic delivery, while maintaining in vivo colloidal stability. This review describes the individual components of the platform, including the mesoporous silica nanoparticle core and supported lipid bilayer, their assembly (by multiple techniques) into a protocell, and the combined, often synergistic, performance of the protocell based on in vitro and in vivo studies, including the assessment of biocompatibility and toxicity. In closing, the many emerging variations of the protocell theme and the future directions for protocell research are commented on. PMID:26780591

  6. Fabrication of high specificity hollow mesoporous silica nanoparticles assisted by Eudragit for targeted drug delivery.

    PubMed

    She, Xiaodong; Chen, Lijue; Velleman, Leonora; Li, Chengpeng; Zhu, Haijin; He, Canzhong; Wang, Tao; Shigdar, Sarah; Duan, Wei; Kong, Lingxue

    2015-05-01

    Hollow mesoporous silica nanoparticles (HMSNs) are one of the most promising carriers for effective drug delivery due to their large surface area, high volume for drug loading and excellent biocompatibility. However, the non-ionic surfactant templated HMSNs often have a broad size distribution and a defective mesoporous structure because of the difficulties involved in controlling the formation and organization of micelles for the growth of silica framework. In this paper, a novel "Eudragit assisted" strategy has been developed to fabricate HMSNs by utilising the Eudragit nanoparticles as cores and to assist in the self-assembly of micelle organisation. Highly dispersed mesoporous silica spheres with intact hollow interiors and through pores on the shell were fabricated. The HMSNs have a high surface area (670 m(2)/g), small diameter (120 nm) and uniform pore size (2.5 nm) that facilitated the effective encapsulation of 5-fluorouracil within HMSNs, achieving a high loading capacity of 194.5 mg(5-FU)/g(HMSNs). The HMSNs were non-cytotoxic to colorectal cancer cells SW480 and can be bioconjugated with Epidermal Growth Factor (EGF) for efficient and specific cell internalization. The high specificity and excellent targeting performance of EGF grafted HMSNs have demonstrated that they can become potential intracellular drug delivery vehicles for colorectal cancers via EGF-EGFR interaction. PMID:25617610

  7. Bioprobes Based on Aptamer and Silica Fluorescent Nanoparticles for Bacteria Salmonella typhimurium Detection.

    PubMed

    Wang, Qiu-Yue; Kang, Yan-Jun

    2016-12-01

    In this study, we have developed an efficient method based on single-stranded DNA (ssDNA) aptamers along with silica fluorescence nanoparticles for bacteria Salmonella typhimurium detection. Carboxyl-modified Tris(2,2'-bipyridyl)dichlororuthenium(II) hexahydrate (RuBPY)-doped silica nanoparticles (COOH-FSiNPs) were prepared using reverse microemulsion method, and the streptavidin was conjugated to the surface of the prepared COOH-FSiNPs. The bacteria S. typhimurium was incubated with a specific ssDNA biotin-labeled aptamer, and then the aptamer-bacteria conjugates were treated with the synthetic streptavidin-conjugated silica fluorescence nanoprobes (SA-FSiNPs). The results under fluorescence microscopy show that SA-FSiNPs can be applied effectively for the labeling of bacteria S. typhimurium with great photostable property. To further verify the specificity of SA-FSiNPs out of multiple bacterial conditions, variant concentrations of bacteria mixtures composed of bacteria S. typhimurium, Escherichia coli, and Bacillus subtilis were treated with SA-FSiNPs.In addition, the feasibility of SA-FSiNPs for bacteria S. typhimurium detection in chicken samples was assessed. All the results display that the established aptamer-based nanoprobes exhibit the superiority for bacteria S. typhimurium detection, which is referentially significant for wider application prospects in pathogen detection. PMID:26983430

  8. pH and ion strength modulated ionic species loading in mesoporous silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Liu, Jianbo; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Yang, Meng; Li, Li; Xu, Jianguo

    2013-10-01

    Mesoporous silica nanoparticles (MSN) have emerged as appealing host materials to accommodate guest molecules for biomedical applications, and recently various methods have been developed to modulate the loading of guest molecules in the silica matrix. Herein, it was demonstrated that pH and ion strength showed great influence on the loading of charged species into the nanoparticles, taking MCM-41 as a host MSN model and methylviologen (MV2+) and 1,5-naphthalene disulfonate (NDS2-) as typical charged ionic guest molecules. As the pH increased from 3.0 to 8.0, the loading amount of MV2+ increased gradually, while on the contrary, it decreased gradually for NDS2-, for the solution pH changed the electrostatic interaction between the silica matrix and the ionic guest molecules. Additionally, the adding of NaCl reduced the electrostatic interaction, which resulted in a decreasing of the electrostatic rejection and electrostatic accumulation for the molecules carrying the same and the opposite charge to the particle respectively. Thus, pH and ion strength can be employed as simple approaches to modulate the loading of charged molecules and permselectivity in MSN. This work has a definite guidance function for molecule loading, transport modulation, controlled release as well as sensors based on MSN.

  9. Molecular Imprinting of Silica Nanoparticle Surfaces via Reversible Addition-Fragmentation Polymerization for Optical Biosensing Applications

    NASA Astrophysics Data System (ADS)

    Oluz, Zehra; Nayab, Sana; Kursun, Talya Tugana; Caykara, Tuncer; Yameen, Basit; Duran, Hatice

    Azo initiator modified surface of silica nanoparticles were coated via reversible addition-fragmentation polymerization (RAFT) of methacrylic acid and ethylene glycol dimethacrylate using 2-phenylprop 2-yl dithobenzoate as chain transfer agent. Using L-phenylalanine anilide as template during polymerization led molecularly imprinted nanoparticles. RAFT polymerization offers an efficient control of grafting process, while molecularly imprinted polymers shows enhanced capacity as sensor. L-phenylalanine anilide imprinted silica particles were characterized by X-Ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM). Performances of the particles were followed by surface plasmon resonance spectroscopy (SPR) after coating the final product on gold deposited glass substrate against four different analogous of analyte molecules: D-henylalanine anilide, L-tyrosine, L-tryptophan and L-phenylalanine. Characterizations indicated that silica particles coated with polymer layer do contain binding sites for L-phenylalanine anilide, and are highly selective for the molecule of interest. This project was supported by TUBITAK (Project No:112M804).

  10. Hyaluronic acid-tagged silica nanoparticles in colon cancer therapy: therapeutic efficacy evaluation

    PubMed Central

    Liu, Kai; Wang, Zhi-qi; Wang, Shi-jiang; Liu, Ping; Qin, Yue-hong; Ma, Yan; Li, Xiao-Chen; Huo, Zhi-Jun

    2015-01-01

    Colon cancer is one of the leading causes of cancer-related death worldwide, and the therapeutic application of 5-fluorouracil (5-FU) is limited due to its nonspecificity, low bioavailability, and overdose. The present study is an attempt to improve the chemotherapeutic efficacy of 5-FU in colon cancers. Therefore, we have prepared 5-FU-loaded hyaluronic acid (HA)-conjugated silica nanoparticles (SiNPs) to target to colon cancer cells. In this study, we have showed the specific binding and intracellular accumulation of targeted nanoparticles based on HA surface modifications in colon carcinoma cells. The particles had spherical shapes with sizes of approximately 130 nm. HA-conjugated nanoparticles showed a sustained release pattern for 5-FU and continuously released for 120 hours. We have further investigated the cytotoxicity potential of targeted and nontargeted nanoparticles in colo-205 cancer cells. IC50 value of 5-FU/hyaluronic acid-conjugated silica nanoparticles (HSNP) was 0.65 µg/mL compared with ~2.8 µg/mL for 5-FU/SNP after 24 hours of incubation. The result clearly showed that HA-conjugated NP was more effective in inducing apoptosis in cancer cells than nontargeted NP. The 5-FU/HSNP showed ~45% of cell apoptosis (early and late apoptosis stage) compared with only 20% for 5-FU/silica nanoparticles (SNP)-treated group. The HA-conjugated nanoparticles provide the possibility of efficient drug transport into tumors that could effectively reduce the side effects in the normal tissues. 5-FU/HSNP was highly efficient in suppressing the tumor growth in xenograft tumor model. The proportion of Ki67 in 5-FU/HSNP-treated group was significantly lower than that of either free drug or nontargeted SiNPs. Altogether, we have showed that conjugation of HA to SiNPs could result in enhanced uptake of 5-FU through CD44-mediated endocytosis uptake and could result in significant antitumor efficacy. Thus, 5-FU/HSNP could be a promising drug delivery system for colon cancer

  11. Fabrication of superhydrophobic and antibacterial surface on cotton fabric by doped silica-based sols with nanoparticles of copper

    PubMed Central

    2011-01-01

    The study discussed the synthesis of silica sol using the sol-gel method, doped with two different amounts of Cu nanoparticles. Cotton fabric samples were impregnated by the prepared sols and then dried and cured. To block hydroxyl groups, some samples were also treated with hexadecyltrimethoxysilane. The average particle size of colloidal silica nanoparticles were measured by the particle size analyzer. The morphology, roughness, and hydrophobic properties of the surface fabricated on cotton samples were analyzed and compared via the scanning electron microscopy, the transmission electron microscopy, the scanning probe microscopy, with static water contact angle (SWC), and water shedding angle measurements. Furthermore, the antibacterial efficiency of samples was quantitatively evaluated using AATCC 100 method. The addition of 0.5% (wt/wt) Cu into silica sol caused the silica nanoparticles to agglomerate in more grape-like clusters on cotton fabrics. Such fabricated surface revealed the highest value of SWC (155° for a 10-μl droplet) due to air trapping capability of its inclined structure. However, the presence of higher amounts of Cu nanoparticles (2% wt/wt) in silica sol resulted in the most slippery smooth surface on cotton fabrics. All fabricated surfaces containing Cu nanoparticles showed the perfect antibacterial activity against both of gram-negative and gram-positive bacteria. PMID:22085594

  12. Adsorption of Surface-Modified Silica Nanoparticles to the Interface of Melt Poly(lactic acid) and Supercritical Carbon Dioxide.

    PubMed

    Sarikhani, K; Jeddi, K; Thompson, R B; Park, C B; Chen, P

    2015-05-26

    With the purpose of fabricating polymer nanocomposite foams and preventing coalescence in foaming processes, the interfacial tension of poly(lactic acid) (PLA)-silica composites is investigated in this work. Synthesized silica nanoparticles (SNs) with a CO2-philic surface modification are used as the dispersed nanoparticles. Interfacial tension is a key parameter in processing of polymer foams since it directly affects the final foam properties, such as cell size and cell density. Interfacial tension of silica-containing PLA and supercritical carbon dioxide (CO2) is measured using axisymmetric drop shape analysis profile (ADSA-P) pendant drop method at high pressures and high temperatures. The interfacial tension between PLA and supercritical CO2 is observed to decrease as a result of the nanoparticles' adsorption to the interface. These results indicate that the reduction in interfacial tension with increasing silica content significantly deviates from a linear trend; there is a minimum at 2 wt % loading of the SNs and then the interfacial tension curve reaches a plateau. Contact angle measurements show an affinity of the SNs for the polymer-supercritical CO2 interface, and these obtained results are used to calculate the binding energy of the nanoparticles to the PLA/CO2 interface. In addition to interfacial properties, the adsorption of silica nanoparticles at the interface is also studied in detail with scanning electron microscopy. PMID:25919815

  13. Biological applications and transmission electron microscopy investigation of mesoporous silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Trewyn, Brian G.

    The research presented and discussed within involves the development of novel biological applications of mesoporous silica nanoparticles (MSN) and an investigation of mesoporous material by transmission electron microscopy (TEM). A series of room-temperature ionic liquid (RTIL) containing mesoporous silica nanoparticle (MSN) materials with various particle morphologies, including spheres, ellipsoids, rods, and tubes, were synthesized. By changing the RTIL template, the pore morphology was tuned from the MCM-41 type of hexagonal mesopores to rotational moire type of helical channels, and to wormhole-like porous structures. These materials were used as controlled release delivery nanodevices to deliver antibacterial ionic liquids against Escherichia coli K12. The involvement of a specific organosiloxane function group, covalently attached to the exterior of fluorescein doped mesoporous silica nanoparticles (FITC-MSN), on the degree and kinetics of endocytosis in cancer and plant cells was investigated. The kinetics of endocystosis of TEG coated FITC-MSN is significantly quicker than FITC-MSN as determined by flow cytometry experiments. The fluorescence confocal microscopy investigation showed the endocytosis of TEG coated-FITC MSN triethylene glycol grafted fluorescein doped MSN (TEG coated-FITC MSN) into both HeLa cells and Tobacco root protoplasts. Once the synthesis of a controlled-release delivery system based on MCM-41-type mesoporous silica nanorods capped by disulfide bonds with superparamagnetic iron oxide nanoparticles was completed. The material was characterized by general methods and the dosage and kinetics of the antioxidant dependent release was measured. Finally, the biological interaction of the material was determined along with TEM measurements. An electron microscopy investigation proved that the pore openings of the MSN were indeed blocked by the Fe 3O4 nanoparticles. The biological interaction investigation demonstrated Fe3O4-capped MSN

  14. Cellular Recognition and Trafficking of Amorphous Silica Nanoparticles by Macrophage Scavenger Receptor A

    SciTech Connect

    Orr, Galya; Chrisler, William B.; Cassens, Kaylyn J.; Tan, Ruimin; Tarasevich, Barbara J.; Markillie, Lye Meng; Zangar, Richard C.; Thrall, Brian D.

    2011-09-01

    The internalization of engineered nanoparticles (ENPs) into cells is known to involve active transport mechanisms, yet the precise biological molecules involved are poorly understood. We demonstrate that the uptake of amorphous silica ENPs (92 nm) by macrophage cells is strongly inhibited by silencing expression of scavenger receptor A (SR-A). In addition, ENP uptake is augmented by introducing SR-A expression into human cells that are normally non-phagocytic. Confocal fluorescent microscopy analyses show that the majority of single or small clusters of silica ENPs co-localize intracellularly with SR-A and are internalized through a pathway characteristic of clathrin-dependent endocytosis. In contrast, larger silica NP agglomerates (>500 nm) are poorly co-localized with the receptor, suggesting independent trafficking or internalization pathways are involved. SR-A silencing also caused decreased cellular secretion of pro-inflammatory cytokines in response to silica ENPs. As SR-A is expressed in macrophages throughout the reticulo-endothelial system, this pathway is likely an important determinant of the biodistribution of, and cellular response to ENPs.

  15. Effect of Silica Nanoparticles on Compressive Strength of Leaves-Waste Composite

    NASA Astrophysics Data System (ADS)

    Masturi, Masturi; Aliah, Hasniah; Aji, Mahardika Prasetya; Sagita, Adi Ardian; Bukit, Minsyahril; Sustini, Euis; Khairurrijal, Khairurrijal; Abdullah, Mikrajuddin

    2011-12-01

    The utilization of solid-waste, especially leaves-waste is one of interesting research of environmental field. One of them is making a composite using polyvinyl acetate (PVAc) polymer as binder (matrix) and silica nanoparticles as reinforcement (filler) to improve the strength of composite-produced. Those raw materials preliminary were mixed by simple mixing with varied compositions and then hot-pressed at 36 MPa and 100 °C for 20 minutes. From compressive strength test, it was found that composite with composition 7:8 of PVAc and leaves-waste had maximum compressive strength, i.e. 57.60 MPa. It was also that the enhancement of strength due to PVAc fraction (w/w) increasing is a percolation behavior, even though its mathematical explanation has not been performed. Into composition of maximum strength above, silica with average size is 74 nm then was added to improve the strength and found that at silica weight fraction of 0.79 (%w/w), the composite had optimum compressive strength, i.e. 70.5 MPa, or increased up to 22.4% of that without silica. The final compressive strength was very comparable to some building goods such as sandstones and bricks. The composite density was also measured and obtained that it was about 0.9 g/cm3 that is very close to some usual woods.

  16. Surface spin-glass in cobalt ferrite nanoparticles dispersed in silica matrix

    NASA Astrophysics Data System (ADS)

    Zeb, F.; Sarwer, W.; Nadeem, K.; Kamran, M.; Mumtaz, M.; Krenn, H.; Letofsky-Papst, I.

    2016-06-01

    Surface effects in cobalt ferrite (CoFe2O4) nanoparticles dispersed in a silica (SiO2) matrix were studied by using AC and DC magnetization. Nanoparticles with different concentration of SiO2 were synthesized by using sol-gel method. Average crystallite size lies in the range 25-34 nm for different SiO2 concentration. TEM image showed that particles are spherical and elongated in shape. Nanoparticles with higher concentration of SiO2 exhibit two peaks in the out-of-phase ac-susceptibility. First peak lies in the high temperature regime and corresponds to average blocking temperature of the nanoparticles. Second peak lies in the low temperature regime and is attributed to surface spin-glass freezing in these nanoparticles. Low temperature peak showed SiO2 concentration dependence and was vanished for large uncoated nanoparticles. The frequency dependence of the AC-susceptibility of low temperature peak was fitted with dynamic scaling law which ensures the presence of spin-glass behavior. With increasing applied DC field, the low temperature peak showed less shift as compared to blocking peak, broaden, and decreased in magnitude which also signifies its identity as spin-glass peak for smaller nanoparticles. M-H loops showed the presence of more surface disorder in nanoparticles dispersed in 60% SiO2 matrix. All these measurements revealed that surface effects become strengthen with increasing SiO2 matrix concentration and surface spins freeze in to spin-glass state at low temperatures.

  17. Monolithic stationary phases with incorporated fumed silica nanoparticles. Part II. Polymethacrylate-based monolithic column with "covalently" incorporated modified octadecyl fumed silica nanoparticles for reversed-phase chromatography.

    PubMed

    Aydoğan, Cemil; El Rassi, Ziad

    2016-05-01

    This study is concerned with the incorporation of surface modified fumed silica nanoparticles (FSNPs) into polymethacrylate based monolithic columns for use in reversed phase chromatography (RPC) of small solutes and proteins. First, FSNPs were modified with 3-(trimethoxysilyl)propylmethacrylate (TMSPM) to yield the "hybrid" methacryloyl fumed silica nanoparticle (MFSNP) monomer. The resulting MFSNP was then mixed with glyceryl monomethacrylate (GMM) and ethylene dimethacrylate (EDMA) in a binary porogenic solvent composed of cyclohexanol and dodecanol, and the in situ copolymerization of MFSNP, GMM and EDMA was performed in a stainless steel column of 4.6 mm i.d. The silanol groups of the hybrid monolith thus obtained were grafted with octadecyl ligands by perfusing the hybrid monolithic column with a solution of 4% w/v of dimethyloctadecylchlorosilane (DODCS) in toluene while the column was maintained at 110°C for 6h (in a heated HPLC oven). One of the originalities of this study was to demonstrate MFSNP as a novel derivatized "hybrid monomer" in making RPC monolithic columns with surface bound octadecyl ligands. In this respect, the RPC behavior of the monolithic column with "covalently" incorporated FNSPs having surface grafted octadecyl ligands was evaluated with alkylbenzenes, aniline derivatives and phenolic compounds. The results showed that the hybrid poly(GMA-EDMA-MFSNP) having surface bound octadecyl ligands exhibited hydrophobic interactions under reversed phase elution conditions. Furthermore, six standard proteins were baseline separated on the column using a 10min linear gradient elution at increasing ACN concentration in the mobile phase at a flow rate of 1.0mL/min using a 10 cm×4.6mm i.d. column. The relative standard deviations (RSDs) for the retention times of the tested solutes were lower than 2.1% and 2.4% under isocratic elution and gradient elution conditions, respectively. PMID:27059396

  18. Mesoporous Silica Nanoparticles Decorated with Carbosilane Dendrons as New Non-viral Oligonucleotide Delivery Carriers.

    PubMed

    Martínez, Ángel; Fuentes-Paniagua, Elena; Baeza, Alejandro; Sánchez-Nieves, Javier; Cicuéndez, Mónica; Gómez, Rafael; de la Mata, F Javier; González, Blanca; Vallet-Regí, María

    2015-10-26

    A novel nanosystem based on mesoporous silica nanoparticles covered with carbosilane dendrons grafted on the external surface of the nanoparticles is reported. This system is able to transport single-stranded oligonucleotide into cells, avoiding an electrostatic repulsion between the cell membrane and the negatively charged nucleic acids thanks to the cationic charge provided by the dendron coating under physiological conditions. Moreover, the presence of the highly ordered pore network inside the silica matrix would make possible to allocate other therapeutic agents within the mesopores with the aim of achieving a double delivery. First, carbosilane dendrons of second and third generation possessing ammonium or tertiary amine groups as peripheral functional groups were prepared. Hence, different strategies were tested in order to obtain their suitable grafting on the outer surface of the nanoparticles. As nucleic acid model, a single-stranded DNA oligonucleotide tagged with a fluorescent Cy3 moiety was used to evaluate the DNA adsorption capacity. The hybrid material functionalised with the third generation of a neutral dendron showed excellent DNA binding properties. Finally, the cytotoxicity as well as the capability to deliver DNA into cells, was tested in vitro by using a human osteoblast-like cell line, achieving good levels of internalisation of the vector DNA/carbosilane dendron-functionalised material without affecting the cellular viability. PMID:26361378

  19. Fluorescent core-shell silica nanoparticles: an alternative radiative materials platform

    NASA Astrophysics Data System (ADS)

    Herz, Erik; Burns, Andrew; Lee, Stephanie; Sengupta, Prabuddha; Bonner, Daniel; Ow, Hooisweng; Liddell, Chekesha; Baird, Barbara; Wiesner, Ulrich

    2006-02-01

    We report on monodisperse fluorescent core-shell silica nanoparticles (C dots) with enhanced brightness and photostability as compared to parent free dye in aqueous solution. Dots containing either tetramethylrhodamine or 7-nitrobenz-2-oxa-1,3-diazole dyes with diameters ranging from tens of nanometers to microns are discussed. The benefits of the core-shell architecture are described in terms of enhanced fluorescent yield of the fluorophores in the quasi-solid-state environment within the particle as compared with parent free dye in water. Several applications of these particles in the fields of photonics and the life sciences are discussed. Specifically, fluorescent core-shell silica nanoparticles are investigated as an active medium for photonic building blocks assembled on zinc sulfide-based seed particles. Initial assembly results for these composite raspberry structures are shown. Finally, applications in the life sciences are explored, including targeting of specific antibody receptors using these single-emission nanoparticles. We expand on single-emission core-shell architecture to incorporate environmentally-sensitive fluorophores to create quantitative ratiometric nanoscale sensors capable of interrogating chemical concentrations on the sub-cellular to molecular levels and demonstrate initial results of intracellular pH imaging. The concept of a single particle laboratory (SPL) is introduced as an active investigator of its environment.

  20. Mixtures of Supported and Hybrid Lipid Membranes on Heterogeneously Modified Silica Nanoparticles

    PubMed Central

    Piper-Feldkamp, Aundrea R.; Wegner, Maria; Brzezinski, Peter; Reed, Scott M.

    2013-01-01

    Simple supported lipid bilayers do not accurately reflect the complex heterogeneity of cellular membranes; however, surface modification makes it possible to tune membrane properties to better mimic biological systems. Here, 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (DETAS), a silica modifier, facilitated formation of supported lipid bilayers on silica nanoparticles. Evidence for a stable supported bilayer came from the successful entrapment of a soluble fluorophore within an interstitial water layer. A fluorescence-quenching assay that utilized a pore-forming peptide was used to demonstrate the existence of two separate lipid leaflets. In this assay, fluorescence was quenched by dithionite in roughly equal proportions prior to and after addition of melittin. When a hydrophobic modifier, octadecyltriethoxysilane, was co-deposited on the nanoparticles with DETAS, there was a decrease in the amount of supported bilayer on the nanoparticles and an increase in the quantity of hybrid membrane. This allowed for a controlled mixture of two distinct types of membranes on a single substrate, one separated by a water cushion and the other anchored directly on the surface, thereby providing a new mimic of cellular membranes. PMID:23387352

  1. Vapor Sensing Using Conjugated Molecule-Linked Au Nanoparticles in a Silica Matrix

    DOE PAGESBeta

    Dirk, Shawn M.; Howell, Stephen W.; Price, B. Katherine; Fan, Hongyou; Washburn, Cody; Wheeler, David R.; Tour, James M.; Whiting, Joshua; Simonson, R. Joseph

    2009-01-01

    Cross-linkedmore » assemblies of nanoparticles are of great value as chemiresistor-type sensors. Herein, we report a simple method to fabricate a chemiresistor-type sensor that minimizes the swelling transduction mechanism while optimizing the change in dielectric response. Sensors prepared with this methodology showed enhanced chemoselectivity for phosphonates which are useful surrogates for chemical weapons. Chemoselective sensors were fabricated using an aqueous solution of gold nanoparticles that were then cross-linked in the presence of the silica precursor, tetraethyl orthosilicate with the α -, ω -dithiolate (which is derived from the in situ deprotection of 1,4-di(Phenylethynyl- 4 ′ , 4 ″ -diacetylthio)-benzene ( 1 ) with wet triethylamine). The cross-linked nanoparticles and silica matrix were drop coated onto interdigitated electrodes having 8  μ m spacing. Samples were exposed to a series of analytes including dimethyl methylphosphonate (DMMP), octane, and toluene. A limit of detection was obtained for each analyte. Sensors assembled in this fashion were more sensitive to dimethyl methylphosphonate than to octane by a factor of 1000.« less

  2. A new strategy for intracellular delivery of enzyme using mesoporous silica nanoparticles: superoxide dismutase.

    PubMed

    Chen, Yi-Ping; Chen, Chien-Tsu; Hung, Yann; Chou, Chih-Ming; Liu, Tsang-Pai; Liang, Ming-Ren; Chen, Chao-Tsen; Mou, Chung-Yuan

    2013-01-30

    We developed mesoporous silica nanoparticle (MSN) as a multifunctional vehicle for enzyme delivery. Enhanced transmembrane delivery of a superoxide dismutase (SOD) enzyme embedded in MSN was demonstrated. Conjugation of the cell-penetrating peptide derived from the human immunodeficiency virus 1 (HIV) transactivator protein (TAT) to mesoporous silica nanoparticle is shown to be an effective way to enhance transmembrane delivery of nanoparticles for intracellular and molecular therapy. Cu,Zn-superoxide dismutase (SOD) is a key antioxidant enzyme that detoxifies intracellular reactive oxygen species, ROS, thereby protecting cells from oxidative damage. In this study, we fused a human Cu,Zn-SOD gene with TAT in a bacterial expression vector to produce a genetic in-frame His-tagged TAT-SOD fusion protein. The His-tagged TAT-SOD fusion protein was expressed in E. coli using IPTG induction and purified using FMSN-Ni-NTA. The purified TAT-SOD was conjugated to FITC-MSN forming FMSN-TAT-SOD. The effectiveness of FMSN-TAT-SOD as an agent against ROS was investigated, which included the level of ROS and apoptosis after free radicals induction and functional recovery after ROS damage. Confocal microscopy on live unfixed cells and flow cytometry analysis showed characteristic nonendosomal distribution of FMSN-TAT-SOD. Results suggested that FMSN-TAT-SOD may provide a strategy for the therapeutic delivery of antioxidant enzymes that protect cells from ROS damage. PMID:23289802

  3. Comparison of Nanoparticle Exposures Between Fumed and Sol-gel Nano-silica Manufacturing Facilities

    PubMed Central

    OH, Sewan; KIM, Boowook; KIM, Hyunwook

    2014-01-01

    Silica nanoparticles (SNPs) are widely used all around the world and it is necessary to evaluate appropriate risk management measures. An initial step in this process is to assess worker exposures in their current situation. The objective of this study was to compare concentrations and morphologic characteristics of fumed (FS) and sol-gel silica nanoparticles (SS) in two manufacturing facilities. The number concentration (NC) and particle size were measured by a real-time instrument. Airborne nanoparticles were subsequently analyzed using a TEM/EDS. SNPs were discharged into the air only during the packing process, which was the last manufacturing step in both the manufacturing facilities studied. In the FS packing process, the geometric mean (GM) NC in the personal samples was 57,000 particles/cm3. The geometric mean diameter (GMD) measured by the SMPS was 64 nm. Due to the high-temperature formation process, the particles exhibited a sintering coagulation. In the SS packing process that includes a manual jet mill operation, the GM NC was calculated to be 72,000 particles/cm3 with an assumption of 1,000,000 particles/cm3 when the upper limit is exceeded (5% of total measure). The particles from SS process had a spherical-shaped morphology with GMD measured by SMPS of 94 nm. PMID:24583511

  4. Dioxetane-doped silica nanoparticles as ultrasensitive reagentless thermochemiluminescent labels for bioanalytics.

    PubMed

    Roda, Aldo; Di Fusco, Massimo; Quintavalla, Arianna; Guardigli, Massimo; Mirasoli, Mara; Lombardo, Marco; Trombini, Claudio

    2012-11-20

    Thermochemiluminescence (TCL; the light emission originating by the thermally triggered decomposition of a molecule) was proposed in the late 1980s as a detection technique for immunoassays. However, after little pioneering work, this technique was abandoned because of the high temperatures required and the poor detectability in comparison to other labels. Here we describe for the first time a thermochemiluminescent acridine-based 1,2-dioxetane with a remarkably low (i.e., below 100 °C) emission-triggering temperature, which made it possible to obtain light emission even in an aqueous environment, as well as amino-functionalized silica nanoparticles loaded with this compound and the fluorescent energy acceptor dipyridamole. Thanks to the signal amplification due to the large number of 1,2-dioxetane molecules in each nanoparticle (about 10(4)) and the increased emission efficiency due to energy transfer to the fluorescent acceptor, the doped nanoparticles could be revealed with a detectability close to that of chemiluminescent enzyme labels (the limit of detection of doped nanoparticles by TCL imaging was 1 × 10(-16) mol mm(-2), thus approaching the value of 5 × 10(-17) mol mm(-2) obtained for the enzyme label horseradish peroxidase with chemiluminescence detection). They could thus be used as highly detectable labels in the development of sensitive TCL-based immunoassays and nucleic acid hybridization assays, in which the detection step does not require any additional chemical reagent. We believe that these doped silica nanoparticles could pave the way for the revival of TCL detection in bioanalytics, taking advantage of the reagentless detection and the high signal/noise ratio in comparison with conventional luminescence detection techniques. PMID:23121217

  5. Colorimetric-Based Detection of TNT Explosives Using Functionalized Silica Nanoparticles

    PubMed Central

    Idros, Noorhayati; Ho, Man Yi; Pivnenko, Mike; Qasim, Malik M.; Xu, Hua; Gu, Zhongze; Chu, Daping

    2015-01-01

    This proof-of-concept study proposes a novel sensing mechanism for selective and label-free detection of 2,4,6-trinitrotoluene (TNT). It is realized by surface chemistry functionalization of silica nanoparticles (NPs) with 3-aminopropyl-triethoxysilane (APTES). The primary amine anchored to the surface of the silica nanoparticles (SiO2-NH2) acts as a capturing probe for TNT target binding to form Meisenheimer amine–TNT complexes. A colorimetric change of the self-assembled (SAM) NP samples from the initial green of a SiO2-NH2 nanoparticle film towards red was observed after successful attachment of TNT, which was confirmed as a result of the increased separation between the nanoparticles. The shift in the peak wavelength of the reflected light normal to the film surface (λpeak) and the associated change of the peak width were measured, and a merit function taking into account their combined effect was proposed for the detection of TNT concentrations from 10−12 to 10−4 molar. The selectivity of our sensing approach is confirmed by using TNT-bound nanoparticles incubated in AptamerX, with 2,4-dinitrotoluene (DNT) and toluene used as control and baseline, respectively. Our results show the repeatable systematic color change with the TNT concentration and the possibility to develop a robust, easy-to-use, and low-cost TNT detection method for performing a sensitive, reliable, and semi-quantitative detection in a wide detection range. PMID:26046595

  6. Micropatterning of silica nanoparticles by electrospray deposition through a stencil mask.

    PubMed

    Higashi, Kazuhiko; Uchida, Kazuhiro; Hotta, Atsushi; Hishida, Koichi; Miki, Norihisa

    2014-02-01

    This article describes the local deposition, or micropatterning, of silica nanoparticles (NPs) using an electrospray method with a stencil mask. The proposed technique can be carried out in a single step at room temperature and atmospheric pressure under dry conditions, allowing it to be used with water- or vacuum-sensitive materials, and leading to cost reductions and high throughput. An evaluation of the patterning accuracy using a 20 µm thick mask showed that for patterns with line widths greater than 50 µm, the pattern was reproduced with an accuracy greater than 95%. When silver NPs were preferably deposited on the silica NPs using a modified silver mirror reaction, they were found to exhibit strong surface-enhanced Raman scattering effects. The proposed process is readily applicable to the development of high-performance micro total analysis systems. PMID:23821680

  7. Thermal Stability and Catalytic Activity of Gold Nanoparticles Supported on Silica

    SciTech Connect

    Veith, G.; Lupini, A; Rashkeev, S; Pennycook, S; Mullins, D; Schwartz, V; Bridges, C; Dudney, N

    2009-01-01

    2.5 nm gold nanoparticles were grown on a fumed silica support, using the physical vapor deposition technique of magnetron sputtering, that are thermally stable when annealed in an oxygen containing environment up to at least 500 C. Traditional Au/TiO{sub 2} catalysts rapidly sinter to form large 13.9 nm gold clusters under these annealing conditions. This surprising stability of Au/SiO{sub 2} is attributed to the absence of residual impurities (ensured by the halide-free production method) and a strong bond between gold and defects at the silica surface (about 3 eV per bond) estimated from density functional theory (DFT) calculations. The Au/SiO{sub 2} catalysts are less active for CO oxidation than the prototypical Au/TiO2 catalysts, however they can be regenerated far more easily, allowing the activity of a catalyst to be fully recovered after deactivation.

  8. Mesoporous silica nanoparticles with controllable morphology prepared from oil-in-water emulsions.

    PubMed

    Gustafsson, Hanna; Isaksson, Simon; Altskär, Annika; Holmberg, Krister

    2016-04-01

    Mesoporous silica nanoparticles are an important class of materials with a wide range of applications. This paper presents a simple protocol for synthesis of particles as small as 40nm and with a pore size that can be as large as 9nm. Reaction conditions including type of surfactant, type of catalyst and presence of organic polymer were investigated in order to optimize the synthesis. An important aim of the work was to understand the mechanism behind the formation of these unusual structures and an explanation based on silica condensation in the small aqueous microemulsion droplets that are present inside the drops of an oil-in-water emulsion is put forward. PMID:26803604

  9. Stability in the memory state of the silica nanoparticle-doped hybrid aligned nematic device

    NASA Astrophysics Data System (ADS)

    Huang, Chi-Yen; Chen, Jian-Hong; Hsieh, Chia-Ting; Song, Heng-Cheng; Wang, Yu-Wu; Horng, Lance; Tian, Ching-Jui; Hwang, Shug-June

    2011-01-01

    We investigate the stability in the memory state of the silica nanoparticle doped hybrid aligned nematic (SN-HAN) cell. The mixed polyimide (PI)-coated planar substrate provides the SN-HAN cell with a stable memory state. The mixed PI comprises the homogeneous PI and small amounts of the homeotropic PI (H-PI). The tiny H-PI dopant decreases the surface energy, increases the roughness of the planar substrate, and increases the pretilt angle of the liquid crystals (LCs). When the pretilt angle is high, the relaxation torque that rewinds the LCs from the electrically addressed homeotropic state to the originally HAN state is too small to break the formed aggregated silica networks, which stabilize the LCs at the electrically addressed homeotropic state. Consequently, the memory state of the SN-HAN cell is stable when the pretilt angle of the LCs is high.

  10. 3D plasmonic transducer based on gold nanoparticles produced by laser ablation on silica nanowires

    NASA Astrophysics Data System (ADS)

    Gontad, F.; Caricato, A. P.; Manera, M. G.; Colombelli, A.; Resta, V.; Taurino, A.; Cesaria, M.; Leo, C.; Convertino, A.; Klini, A.; Perrone, A.; Rella, R.; Martino, M.

    2016-05-01

    Silica two-dimensional substrates and nanowires (NWs) forests have been successfully decorated with Au nanoparticles (NPs) through laser ablation by using a pulsed ArF excimer laser, for sensor applications. A uniform coverage of both substrate surfaces with NPs has been achieved controlling the number of laser pulses. The annealing of the as-deposited particles resulted in a uniform well-defined distribution of spherical NPs with an increased average diameter up to 25 nm. The deposited samples on silica NWs forest present a very good plasmonic resonance which resulted to be very sensitive to the changes of the environment (ethanol/water solutions with increasing concentration of ethanol) allowing the detection of changes on the second decimal digit of the refractive index, demonstrating its potentiality for further biosensing functionalities.

  11. Second-harmonic response of multilayer nanocomposites of silver-decorated nanoparticles and silica

    PubMed Central

    Zdanowicz, Mariusz; Harra, Juha; Mäkelä, Jyrki M.; Heinonen, Esa; Ning, Tingyin; Kauranen, Martti; Genty, Goëry

    2014-01-01

    We perform a detailed characterisation of the second-order nonlinear optical response of nanocomposites consisting of alternating layers of silver-decorated silica glass nanoparticles and pure silica glass. The samples are fabricated using aerosol techniques and electron-beam dielectric coating, resulting in a bulk-like material with symmetry-breaking induced by the porosity of the alternating layers. The second-order nonlinear response increases with the number of layers. Further, by determining the components of the second-order susceptibility tensor of the samples, we show that the structural properties of the samples are well maintained as the sample thickness is increased. Our results form an important baseline for any further optimization of these types of structures, which can be fabricated using very straightforward methods. PMID:25034367

  12. Silica nanoparticle: a potential new insecticide for mosquito vector control.

    PubMed

    Barik, Tapan K; Kamaraju, Raghavendra; Gowswami, Arunava

    2012-09-01

    Presently, there is a need for increased efforts to develop newer and effective methods to control mosquito vectors as the existing chemical and biological methods are not as effective as in earlier period owing to different technical and operational reasons. The use of nanomaterial products in various sectors of science including health increased during the last decade. We tested three types of nanosilica, namely lipophilic, hydrophilic and hydrophobic, to assess their larvicidal, pupicidal and growth inhibitor properties and also their influence on oviposition behaviour (attraction/deterrence) of mosquito species that transmit human diseases, namely malaria (Anopheles), yellow fever, chickungunya and dengue (Aedes), lymphatic filariasis and encephalitis (Culex and Aedes). Application of hydrophobic nanosilica at 112.5 ppm was found effective against mosquito species tested. The larvicidal effect of hydrophobic nanosilica on mosquito species tested was in the order of Anopheles stephensi > Aedes aegypti > Culex quinquefasciatus, and the pupicidal effect was in the order of A. stephensi > C. quinquefasciatus > Ae. aegypti. Results of combined treatment of hydrophobic nanosilica with temephos in larvicidal test indicated independent toxic action without any additive effect. This is probably the first report that demonstrated that nanoparticles particularly nanosilica could be used in mosquito vector control. PMID:22565400

  13. Superhydrophobic durable coating based on UV-photoreactive silica nanoparticles

    SciTech Connect

    Nahum, T.; Dodiuk, H.; Dotan, A.; Kenig, S.; Lellouche, J. P.

    2015-05-22

    Superhydrophobic surfaces with contact angle (CA) >150 and sliding angle (SA) <10 have been aroused curiosity over the years due to their various applications. Superhydrophobicity can be obtained tailoring the chemistry and the roughness of the surface, mimicking the Lotus flower. Most superhydrophobic surfaces based on secondary bonding lose their roughness in harsh conditions and are unsuitable for practical applications. Photoreactive SiO{sub 2} nanoparticles (NPs) based on benzophenone (BP) can be a very effective tool for formation of reactive species that function as a molecular bridge by covalent bonding between the NP and any polymer matrix with C-C and C-H bonds. The present work focused on thermoset radiation curing urethane acrylate. Upon UV irradiation reactive excited nπ* triplet benzophenone species are formed and react through hydrogen abstraction to form ketyl radicals which interact with a radicals from the UV irradiated polymer matrix to yield covalent bonding. Roughness was achieved by dipping the substrate in SiO{sub 2}@BPs NPs dispersion followed by irradiation. Fluoroalkylsilane was used to obtain hydrophobic top layer. AFM nano manipulation was used to verify the immobilization of NPs. Evaluation of durability was made using air flow at 300 km/hr. Preliminary results indicate the formation of super hydrophobic surfaces (CA>150 and SA<10) with improved stability.

  14. Superhydrophobic durable coating based on UV-photoreactive silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Nahum, T.; Dodiuk, H.; Dotan, A.; Kenig, S.; Lellouche, J. P.

    2015-05-01

    Superhydrophobic surfaces with contact angle (CA) >150 and sliding angle (SA) <10 have been aroused curiosity over the years due to their various applications. Superhydrophobicity can be obtained tailoring the chemistry and the roughness of the surface, mimicking the Lotus flower. Most superhydrophobic surfaces based on secondary bonding lose their roughness in harsh conditions and are unsuitable for practical applications. Photoreactive SiO2 nanoparticles (NPs) based on benzophenone (BP) can be a very effective tool for formation of reactive species that function as a molecular bridge by covalent bonding between the NP and any polymer matrix with C-C and C-H bonds. The present work focused on thermoset radiation curing urethane acrylate. Upon UV irradiation reactive excited nπ* triplet benzophenone species are formed and react through hydrogen abstraction to form ketyl radicals which interact with a radicals from the UV irradiated polymer matrix to yield covalent bonding. Roughness was achieved by dipping the substrate in SiO2@BPs NPs dispersion followed by irradiation. Fluoroalkylsilane was used to obtain hydrophobic top layer. AFM nano manipulation was used to verify the immobilization of NPs. Evaluation of durability was made using air flow at 300 km/hr. Preliminary results indicate the formation of super hydrophobic surfaces (CA>150 and SA<10) with improved stability.

  15. Antimicrobial and wound healing properties of nitric oxide-releasing xerogels and silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Hetrick, Evan M.

    Indwelling medical devices continue to be plagued by the body's response to foreign materials and the ever-present threat of microbial infection. Endogenously-produced nitric oxide (NO) has been shown to play beneficial roles in both wound healing and the body's defense against infection. To exploit NO's favorable properties for biomaterials applications, previous studies have detailed the synthesis of xerogel polymers and silica nanoparticles capable of storing and releasing NO via diazeniumdiolate NO-donors. Here, the ability of NO-releasing materials to reduce bacterial adhesion under flow conditions, modulate the foreign body response, and kill microbial pathogens is described. To more thoroughly characterize the antibacterial properties of NO-releasing xerogels, studies were conducted with Pseudomonas aeruginosa in a parallel plate flow cell. Xerogels modified to release NO reduced bacterial adhesion in a flux-dependent manner, with a NO flux of ˜21 pmol·cm -2·s-1 inhibiting P. aeruginosa adhesion by 65% compared to controls. Fluorescent viability probes indicated that bacteria adhered to NO-releasing xerogels were killed within 7 h of adhesion. In terms of tissue biocompatibility, the foreign body response was studied in an animal model at the site of subcutaneous implants coated with NO-releasing xerogels. Implant-derived NO reduced capsule thickness and the chronic inflammatory response by 50 and 30%, respectively, compared to controls. Additionally, 77% more blood vessels were observed in proximity to NO-releasing implants after 1 week compared to controls. Along with their ability to reduce bacterial adhesion and mitigate the foreign body response, NO-releasing materials may prove useful for treating infections due to the broad-spectrum antimicrobial properties of NO. Recently, silica nanoparticles have been developed that release micromolar quantities of NO, and here the efficacy of such nanoparticles was examined against both planktonic and biofilm

  16. Mesoporous silica nanoparticles with organo-bridged silsesquioxane framework as innovative platforms for bioimaging and therapeutic agent delivery.

    PubMed

    Du, Xin; Li, Xiaoyu; Xiong, Lin; Zhang, Xueji; Kleitz, Freddy; Qiao, Shi Zhang

    2016-06-01

    Mesoporous silica material with organo-bridged silsesquioxane frameworks is a kind of synergistic combination of inorganic silica, mesopores and organics, resulting in some novel or enhanced physicochemical and biocompatible properties compared with conventional mesoporous silica materials with pure Si-O composition. With the rapid development of nanotechnology, monodispersed nanoscale periodic mesoporous organosilica nanoparticles (PMO NPs) and organo-bridged mesoporous silica nanoparticles (MSNs) with various organic groups and structures have recently been synthesized from 100%, or less, bridged organosilica precursors, respectively. Since then, these materials have been employed as carrier platforms to construct bioimaging and/or therapeutic agent delivery nanosystems for nano-biomedical application, and they demonstrate some unique and/or enhanced properties and performances. This review article provides a comprehensive overview of the controlled synthesis of PMO NPs and organo-bridged MSNs, physicochemical and biocompatible properties, and their nano-biomedical application as bioimaging agent and/or therapeutic agent delivery system. PMID:27017579

  17. Lanthano phosphomolybdate-decorated silica nanoparticles: novel hybrid materials with photochromic properties.

    PubMed

    Pinto, Tânia V; Fernandes, Diana M; Pereira, Clara; Guedes, Alexandra; Blanco, Ginesa; Pintado, Jose M; Pereira, Manuel F R; Freire, Cristina

    2015-03-14

    Novel photochromic hybrid nanomaterials were prepared through the immobilization of the lacunary Keggin-type phosphomolybdate (TBA4H3[PMo11O39]·xH2O, denoted as PMo11) and sandwich-type lanthano phosphomolybdates (K11[Ln(III)(PMo11O39)2]·xH2O, denoted as Ln(PMo11)2, where Ln(III) = Sm, Eu, Gd, Tb and Dy) onto positively-charged functionalized silica nanoparticles. The functionalized silica nanoparticles were prepared by a one-step co-condensation route between tetraethyl orthosilicate and dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, presenting an average particle size of 95 ± 26 nm, a spherical morphology and a pore diameter of 13.7 nm. All characterization techniques proved the successful immobilization of the phosphomolybdates. The photochromic properties of the resulting hybrid nanomaterials in the solid state were evaluated by UV-Vis spectroscopy and colorimetry. All materials revealed promising photochromic properties under UV irradiation (λ = 254 nm). The lacunary phosphomolybdate anchored onto the silica nanoparticles, C18-SiO2@PMo11, showed the best photoswitching properties, with the color changing from green to dark-blue (ΔE* = 26.8). Among the Ln(PMo11)2-based hybrid nanomaterials, those containing higher Mo loadings--Eu(III)- and Tb(III)-based samples--presented more significant color changes from green to dark-blue (ΔE* = 18.8-18.9). These results revealed that the optical properties of the as-prepared hybrid nanomaterials did not depend directly on the type of Ln(III) cation, but only on the amount of Mo, which was the target element responsible for the photochromic behavior. PMID:25652698

  18. Synthesis of hybrid inorganic/organic nitric oxide-releasing silica nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Carpenter, Alexis Wells

    Nitric oxide (NO) is an endogenously produced free radical involved in a number of physiological processes. Thus, much research has focused on developing scaffolds that store and deliver exogenous NO. Herein, the synthesis of N-diazeniumdiolate-modified silica nanoparticles of various physical and chemical properties for biomedical applications is presented. To further develop NO-releasing silica particles for antimicrobial applications, a reverse microemulsion synthesis was designed to achieve nanoparticles of distinct sizes and similar NO release characteristics. Decreasing scaffold size resulted in improved bactericidal activity against Pseudomonas aeruginosa. Confocal microscopy revealed that the improved efficacy resulted from faster particle-bacterium association kinetics. To broaden the therapeutic potential of NO-releasing silica particles, strategies to tune NO release characteristics were evaluated. Initially, surface hydrophobicity and NO release kinetics were tuned by grafting hydrocarbon- and fluorocarbon-based silanes onto the surface of N-diazeniumdiolate-modified particles. The addition of fluorocarbons resulted in a 10x increase in the NO release half-life. The addition of short-chained hydrocarbons to the particle surface increased their stability in hydrophobic electrospun polyurethanes. Although NO release kinetics were longer than that of unmodified particles, durations were still limited to <7 days. An alternative strategy for increasing NO release duration involved directly stabilizing the N-diazeniumdiolate using O2-protecting groups. O2-Methoxymethyl 1-(4-(3-(trimethoxysilyl)propyl))piperazin-1-yl)diazen-1-ium-1,2-diolate (MOM-Pip/NO) was grafted onto mesoporous silica nanoparticles to yield scaffolds with an NO payload of 2.5 μmol NO/mg and an NO release half-life of 23 d. Doping the MOM-Pip/NO-modified particles into resin composites yielded antibacterial NO-releasing dental restorative materials. A 3-log reduction in viable adhered

  19. Facile Fabrication of Well-Dispersed Pt Nanoparticles in Mesoporous Silica with Large Open Spaces and Their Catalytic Applications.

    PubMed

    Liu, Xianchun; Chen, Dashu; Chen, Lin; Jin, Renxi; Xing, Shuangxi; Xing, Hongzhu; Xing, Yan; Su, Zhongmin

    2016-06-27

    In this paper, a facile strategy is reported for the preparation of well-dispersed Pt nanoparticles in ordered mesoporous silica (Pt@OMS) by using a hybrid mesoporous phenolic resin-silica nanocomposite as the parent material. The phenolic resin polymer is proposed herein to be the key in preventing the aggregation of Pt nanoparticles during their formation process and making contributions both to enhance the surface area and enlarge the pore size of the support. The Pt@OMS proves to be a highly active and stable catalyst for both gas-phase oxidation of CO and liquid-phase hydrogenation of 4-nitrophenol. This work might open new avenues for the preparation of noble metal nanoparticles in mesoporous silica with unique structures for catalytic applications. PMID:27245766

  20. Size-dependent interactions of silica nanoparticles with a flat silica surface.

    PubMed

    Seo, Jihoon; Kim, Joo Hyun; Lee, Myoungjae; Moon, Jinok; Yi, Dong Kee; Paik, Ungyu

    2016-12-01

    We have investigated the surface chemistry of SiO2 nanoparticles (NPs) with different sizes and their corresponding interactions with a flat substrate of surface curvature ∼0. As the size of the NPs increases, the SiO2 surface is increasingly covered with H-bonded silanol groups, thereby increasing the ζ-potential and shifting the isoelectric point higher in pH. Interactions between the SiO2 NPs and the flat SiO2 surface were analyzed in situ using quartz crystal microbalance with dissipation (QCM-D) method, and the results were interpreted based on an extended Derjaguin-Landau-Verwey-Overbeek theory. At very low ionic strength (1mM NaCl), there was no particle adsorption onto the surface due to the highly repulsive energy barriers to this interaction. On the other hand, QCM-D results showed that the significant adsorption of SiO2 NPs onto a flat SiO2 surface occurred under conditions of high ionic strength (100mM NaCl). Interestingly, the adsorption behaviors of three different-sized SiO2 NPs on the surface varied considerably with size. SiO2 NPs with small size have high adsorption affinity with the flat SiO2 surface due to an extremely low energy barrier for the interactions, whereas relatively large SiO2 NPs have very weak adsorption affinity with the flat surface due to the repulsive energy barrier formed by the increase in the electrostatic and hydration repulsion energy. PMID:27552426

  1. Aptamer-Functionalized Fluorescent Silica Nanoparticles for Highly Sensitive Detection of Leukemia Cells

    NASA Astrophysics Data System (ADS)

    Tan, Juntao; Yang, Nuo; Hu, Zixi; Su, Jing; Zhong, Jianhong; Yang, Yang; Yu, Yating; Zhu, Jianmeng; Xue, Dabin; Huang, Yingying; Lai, Zongqiang; Huang, Yong; Lu, Xiaoling; Zhao, Yongxiang

    2016-06-01

    A simple, highly sensitive method to detect leukemia cells has been developed based on aptamer-modified fluorescent silica nanoparticles (FSNPs). In this strategy, the amine-labeled Sgc8 aptamer was conjugated to carboxyl-modified FSNPs via amide coupling between amino and carboxyl groups. Sensitivity and specificity of Sgc8-FSNPs were assessed using flow cytometry and fluorescence microscopy. These results showed that Sgc8-FSNPs detected leukemia cells with high sensitivity and specificity. Aptamer-modified FSNPs hold promise for sensitive and specific detection of leukemia cells. Changing the aptamer may allow the FSNPs to detect other types of cancer cells.

  2. Neoglycoenzyme-Gated Mesoporous Silica Nanoparticles: Toward the Design of Nanodevices for Pulsatile Programmed Sequential Delivery.

    PubMed

    Díez, Paula; Sánchez, Alfredo; de la Torre, Cristina; Gamella, María; Martínez-Ruíz, Paloma; Aznar, Elena; Martínez-Máñez, Ramón; Pingarrón, José M; Villalonga, Reynaldo

    2016-03-01

    We report herein the design of a stimulus-programmed pulsatile delivery system for sequential cargo release based on the use of a lactose-modified esterase as a capping agent in phenylboronic acid functionalized mesoporous silica nanoparticles. The dual-release mechanism was based on the distinct stability of the cyclic boronic acid esters formed with lactose residues and the long naturally occurring glycosylation chains in the modified neoglycoenzyme. Cargo delivery in succession was achieved using glucose and ethyl butyrate as triggers. PMID:26966914

  3. Mesoporous silica nanoparticles with controlled loading of cationic dendrimer for gene delivery

    NASA Astrophysics Data System (ADS)

    Lin, Jian-Tao; Wang, Chao; Zhao, Yi; Wang, Guan-Hai

    2014-09-01

    In this work, a series of polyamidoamine (PAMAM) dendrimer-functionalized mesoporous silica nanoparticles (MSNs) with predictable and adjustable cationic charge densities for gene delivery were designed, synthesized and characterized. The ‘clickable’ MSNs with controlled and randomly distributed azide groups were synthesized by co-condensation method, and PAMAM dendrimer was conjugated to MSNs via quantitative click modification. The structures of PAMAM-functionalized MSNs were characterized by FTIR, XRD and TEM analyses. Dendrimer-functionalized MSNs formed complexes with plasmid DNA (pDNA), and the complexes were successfully transfected into human kidney cell 293 T. The in vitro cytotoxicity and gene transfection efficacy were also investigated.

  4. Aptamer-Functionalized Fluorescent Silica Nanoparticles for Highly Sensitive Detection of Leukemia Cells.

    PubMed

    Tan, Juntao; Yang, Nuo; Hu, Zixi; Su, Jing; Zhong, Jianhong; Yang, Yang; Yu, Yating; Zhu, Jianmeng; Xue, Dabin; Huang, Yingying; Lai, Zongqiang; Huang, Yong; Lu, Xiaoling; Zhao, Yongxiang

    2016-12-01

    A simple, highly sensitive method to detect leukemia cells has been developed based on aptamer-modified fluorescent silica nanoparticles (FSNPs). In this strategy, the amine-labeled Sgc8 aptamer was conjugated to carboxyl-modified FSNPs via amide coupling between amino and carboxyl groups. Sensitivity and specificity of Sgc8-FSNPs were assessed using flow cytometry and fluorescence microscopy. These results showed that Sgc8-FSNPs detected leukemia cells with high sensitivity and specificity. Aptamer-modified FSNPs hold promise for sensitive and specific detection of leukemia cells. Changing the aptamer may allow the FSNPs to detect other types of cancer cells. PMID:27299653

  5. Observation of blue phase in chiral nematic liquid crystal and its stabilization by silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Singh, Arshdeep; Malik, Praveen; Jayoti, Divya

    2016-01-01

    In the present work, we report the blue phase (BP) in a binary mixture of cholesteryl nonanoate (CN) and N-(4-ethoxybenzylidene)-4-butylaniline (EBBA). The mixture exhibits BP over a temperature range of 2.3 K at optimum composition (50:50) of liquid crystals (LCs). The effect of silica nanoparticles (SNPs) doping on thermal stability of BPs has also been demonstrated and nearly 6 K wide BP temperature range was achieved at 0.5 wt.% of SNPs. A porous type texture was also observed during the BP formation process in the doped samples.

  6. Nanoparticle metrology of silica colloids and super-resolution studies using the ADOTA fluorophore

    NASA Astrophysics Data System (ADS)

    Stewart, Hazel L.; Yip, Philip; Rosenberg, Martin; Just Sørensen, Thomas; Laursen, Bo W.; Knight, Alex E.; Birch, David J. S.

    2016-04-01

    We describe how a new fluorescent dye, methyl ADOTA (N-methyl-azadioxatriangulenium tetrafluoroborate), is an improvement on dyes reported previously for measuring silica nanoparticle size in sols using the decay of fluorescence anisotropy. Me(thyl)-ADOTA possesses the unusual combination of having a red emission and a long fluorescence lifetime of ~20 ns, leaving it better-placed to reveal particle sizes at the upper end of the 1-10 nm measurement range. For stable LUDOX colloids, Me-ADOTA is shown to offer higher measurement precision in  ⩽1/30th of the measurement time required for dyes previously used. In measurement times of only ~20 min nanoparticle radii for LUDOX SM-AS, AM and AS-40 of 4.6  ±  0.3 nm, 5.9  ±  0.2 nm and 11.1  ±  1.1 nm, are in good agreement with two of the manufacturer’s values of 3.5 nm, 6 nm and 11 nm respectively. Unlike the Si-ADOTA (N-(4-(triethoxysilylethyl)urea-phenyl-) ADOTA tetrafluoroborate) derivative containing a reactive trimetoxysilane group, Me-ADOTA is shown to not induce aggregation of colloidal silica. Measurements on nanoparticles growing in an acidic silica hydrogel at pH 0.94, prior to the gel time of ~50 h, reveals an average nanoparticle size up to ~6.3 nm, significantly larger than the 4.5 nm reported previously. The difference is most certainly due to the longer fluorescence lifetime of Me-ADOTA (~20 ns) revealing the presence of larger particles. Studies of growing silica clusters in an alcogel of tetraethyl orthosilicate (TEOS) were able to resolve a monotonically increasing average radius of 1.42  ±  0.10 nm to 1.81  ±  0.14 nm over a period of 48 h. We have also assessed a carboxylic acid derivative of ADOTA (N-(3-carboxypropylene)-ADOTA tetrafluoroborate-Acid-ADOTA) using dSTORM super-resolution microscopy. Although demonstrating high photochemical stability and blinking, its lower brightness and relative propensity to aggregate

  7. Phase decomposition of AuFe alloy nanoparticles embedded in silica matrix under swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Pannu, Compesh; Bala, Manju; Singh, U. B.; Srivastava, S. K.; Kabiraj, D.; Avasthi, D. K.

    2016-07-01

    AuFe alloy nanoparticles embedded in silica matrix are synthesized using atom beam sputtering technique and subsequently irradiated with 100 MeV Au ions at various fluences ranging from 1 × 1013 to 6 × 1013 ions/cm2. The X-ray diffraction, absorption spectroscopy, X-ray photo electron spectroscopy and transmission electron microscopy results show that swift heavy ion irradiation leads to decomposition of AuFe alloy nanoparticles from surface region and subsequent reprecipitation of Au and Fe nanoparticles occur. The process of phase decomposition and reprecipitation of individual element nanoparticles is explained on the basis of inelastic thermal spike model.

  8. Effect of hydrophilic silica nanoparticles on the magnetorheological properties of ferrofluids: a study using opto-magnetorheometer.

    PubMed

    Felicia, Leona J; Philip, John

    2015-03-24

    For many technological applications of ferrofluids, the magnetorheological properties require being precisely controlled. We study the effect of hydrophilic silica on the magnetorheology of an oil-based ferrofluid containing Fe3O4 nanoparticles of size ∼10 nm. We observe that the presence of silica nanoparticles lowers the yield stresses, viscoelastic moduli, and shear thinning behavior of the ferrofluid because of the weakening of dipolar interactions, which was evident from the observed lower yield stresses exponent (<2). The ferrofluid containing silica exhibits a dominant elastic behavior, a reduced hysteresis during the forward and reverse magnetic field sweeps, and a longer linear viscoelastic regime under nonlinear deformation. The Mason number plots at low shear rates and magnetic fields show deviations from the master curve in the presence of silica. The magnetic field induced microstructures, visualized using opto-magnetorheometer, showed columnar aggregate structures along the field directions, which are reoriented along the shear flow direction at high shear rates. The image analysis shows that the average thickness of the columnar aggregates in pure ferrofluid is much larger than that of the mixed system, which suggests that the intervening silica matrix hampers the zippering transition of columns at higher magnetic field and shear rates. Our results suggest that optimization of rheological properties of ferrofluids is possible by carefully adding suitable silica nanoparticles, which may find practical applications such as dynamic seals, heat transfer, sensors, and opto-fluidic devices, etc. PMID:25734232

  9. Nanomolar detection of dopamine at multi-walled carbon nanotube grafted silica network/gold nanoparticle functionalised nanocomposite electrodes.

    PubMed

    Komathi, Shanmugasundaram; Gopalan, Anantha Iyengar; Lee, Kwang-Pill

    2010-02-01

    This is the first report on ultrahigh sensitive and selective electrochemical detection of nanomolar concentrations of dopamine (DA) in the presence of ascorbic acid (AA) at a modified electrode fabricated with a new functional nanocomposite, comprising of multi-walled carbon nanotube (MWNT) grafted silica network (silica NW) and gold nanoparticles (Au NPs) (MWNT-g-silica NW/Au NPs). The fabrication of MWNT-g-silica NW/Au NPs modified electrodes involves two steps: covalent functionaliztion of MWNT with silica NW and deposition of Au NP. Cyclic voltammetry and differential pulse voltammetry experiments were performed for the individual and simultaneous electrochemical detection of DA (in nanomolar concentrations) and AA. Differential pulse voltammograms at ITO/MWNT-g-silica NW/Au NPs modified electrode (ME) revealed that the current response is linear for DA in the concentration range of 0.1 nM-30 nM with a detection limit of 0.1 nM. This is the lowest detection limit reported for DA. A plausible mechanism is presented for the excellent performance of ITO/MWNT-g-silica NW/Au NPs-ME towards nanomolar detection of DA. The results revealed that MWNT, silica NW and Au NPs in ITO/MWNT-g-silica NW/Au NPs-ME synergistically contribute to the ultrasensitivity and selectivity for the electrochemical detection of nanomolar concentrations of DA in the presence of coexisting species. PMID:20098776

  10. Mesoporous Silica Nanoparticle-Stabilized and Manganese-Modified Rhodium Nanoparticles as Catalysts for Highly Selective Synthesis of Ethanol and Acetaldehyde from Syngas

    SciTech Connect

    Huang, Yulin; Deng, Weihua; Guo, Enruo; Chung, Po-Wen; Chen, Senniang; Trewyn, Brian; Brown, Robert; Lin, Victor

    2012-03-30

    Well-defined and monodispersed rhodium nanoparticles as small as approximately 2 nm were encapsulated in situ and stabilized in a mesoporous silica nanoparticle (MSN) framework during the synthesis of the mesoporous material. Although both the activity and selectivity of MSN-encapsulated rhodium nanoparticles in CO hydrogenation could be improved by the addition of manganese oxide as expected, the carbon selectivity for C2 oxygenates (including ethanol and acetaldehyde) was unprecedentedly high at 74.5 % with a very small amount of methanol produced if rhodium nanoparticles were modified by manganese oxide with very close interaction.

  11. The interfacial interactions of Tb-doped silica nanoparticles with surfactants and phospholipids revealed through the fluorescent response.

    PubMed

    Bochkova, Olga D; Mustafina, Asiya R; Mukhametshina, Alsu R; Burilov, Vladimir A; Skripacheva, Viktoriya V; Zakharova, Lucia Ya; Fedorenko, Svetlana V; Konovalov, Alexander I; Soloveva, Svetlana E; Antipin, Igor S

    2012-04-01

    The quenching effect of dyes (phenol red and bromothymol blue) on Tb(III)-centered luminescence enables to sense the aggregation of cationic and anionic surfactants near the silica surface of Tb-doped silica nanoparticles (SN) in aqueous solutions. The Tb-centered luminescence of non-decorated SNs is diminished by the inner