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Sample records for fluorescent silica nanoparticles

  1. 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

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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.

  11. 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.

  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. 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

  14. 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.

  15. 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

  16. Folate receptor targeting silica nanoparticle probe for two-photon fluorescence bioimaging

    PubMed Central

    Wang, Xuhua; Yao, Sheng; Ahn, Hyo-Yang; Zhang, Yuanwei; Bondar, Mykhailo V.; Torres, Joseph A.; Belfield, Kevin D.

    2010-01-01

    Narrow dispersity organically modified silica nanoparticles (SiNPs), diameter ~30 nm, entrapping a hydrophobic two-photon absorbing fluorenyl dye, were synthesized by hydrolysis of triethoxyvinylsilane and (3-aminopropyl)triethoxysilane in the nonpolar core of Aerosol-OT micelles. The surface of the SiNPs were functionalized with folic acid, to specifically deliver the probe to folate receptor (FR) over-expressing Hela cells, making these folate two-photon dye-doped SiNPs potential candidates as probes for two-photon fluorescence microscopy (2PFM) bioimaging. In vitro studies using FR over-expressing Hela cells and low FR expressing MG63 cells demonstrated specific cellular uptake of the functionalized nanoparticles. One-photon fluorescence microscopy (1PFM) imaging, 2PFM imaging, and two-photon fluorescence lifetime microscopy (2P-FLIM) imaging of Hela cells incubated with folate-modified two-photon dye-doped SiNPs were demonstrated. PMID:21258480

  17. Indirect immunofluorescence detection of E. coli O157:H7 with fluorescent silica nanoparticles.

    PubMed

    Chen, Ze-Zhong; Cai, Li; Chen, Min-Yan; Lin, Yi; Pang, Dai-Wen; Tang, Hong-Wu

    2015-04-15

    A method of fluorescent nanoparticle-based indirect immunofluorescence assay using either fluorescence microscopy or flow cytometry for the rapid detection of pathogenic Escherichia coli O157:H7 was developed. The dye-doped silica nanoparticles (NPs) were synthesized using W/O microemulsion methods with the combination of 3-aminopropyltriethoxysilane (APTES) and fluorescein isothiocyanate (FITC) and polymerization reaction with carboxyethylsilanetriol sodium salt (CEOS). Protein A was immobilized at the surface of the NPs by covalent binding to the carboxyl linkers and the surface coverage of Protein A on NPs was determined by the Bradford method. Rabbit anti-E. Coli O157:H7 antibody was used as primary antibody to recognize E. coli O157:H7 and then antibody binding protein (Protein A) labeled with FITC-doped silica NPs (FSiNPs) was used to generate fluorescent signal. With this method, E. Coli O157:H7 in buffer and bacterial mixture was detected. In addition, E. coli O157:H7 in several spiked background beef samples were measured with satisfactory results. Therefore, the FSiNPs are applicable in signal-amplified bioassay of pathogens due to their excellent capabilities such as brighter fluorescence and higher photostability than the direct use of conventional fluorescent dyes. PMID:25460888

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. 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

  3. Mixed anionic surfactant-templated mesoporous silica nanoparticles for fluorescence detection of Fe(3.).

    PubMed

    Gai, Fangyuan; Zhou, Tianlei; Chu, Guang; Li, Ye; Liu, Yunling; Huo, Qisheng; Akhtar, Farid

    2016-01-14

    This work demonstrates a novel method for the synthesis of large pore mesoporous silica nanoparticles (MSNs) with a pore diameter of 10.3 nm and a particle diameter of ∼50 nm based on the incorporation of mixed anionic surfactants sodium dodecyl benzene sulfonate (SDBS) and sodium dodecyl sulphate (SDS) as the template in the synthesis process. The dispersity, morphology, pore structure and size of mesoporous nanoparticles were adjusted by changing the molar ratio of two anionic surfactants, the concentration of the co-structure-directing agent (3-aminopropyltrimethoxysilane) and the reaction temperature. The results of synthesis experiments suggested that the formation of large pore MSNs involved a nucleation and growth process. MSNs were post-grafted with a Schiff base moiety for fluorescence sensing of Fe(3+) in water. The applicability of functionalized MSNs was demonstrated by selective fluorescence detection of Fe(3+) in aqueous media. PMID:26616310

  4. Investigating the colloidal stability of fluorescent silica nanoparticles under isotonic conditions for biomedical applications.

    PubMed

    Nooney, Robert I; White, Angela; O'Mahony, Christy; O'Connell, Claire; Kelleher, Susan M; Daniels, Stephen; McDonagh, Colette

    2015-10-15

    Fluorescent silica nanoparticle (NP) labels are of great interest in biomedical diagnostics, however, when used in bioassays under physiological conditions they rapidly agglomerate and precipitate from solution leading to high levels of non-specific binding. In this work, using size and zeta-potential data obtained from Dynamic and Electrophoretic Light Scattering analysis, the improvement in colloidal stability of silica NPs under physiological conditions was correlated with an increase in the concentration of three additives: (1) a protein, bovine serum albumin (BSA); (2) a neutral surfactant, Tween 20®; and (3) a charged surfactant, sodium dodecyl sulfate (SDS). The number of BSA molecules present in the NP corona at each concentration was calculated using UV-Vis spectroscopy and a bicinchoninic acid protein assay (BCA). The optimal concentration of each additive was also effective in stabilizing antibody labeled fluorescent nanoparticles (αNPs) under physiological conditions. Using a fourth additive, trehalose, the colloidal stability of αNPs after freeze-drying and long-term storage also significantly improved. Both as-prepared and freeze-dried αNPs were tested in a standard fluorescence immunoassay for the detection of human IgG. The as-prepared assay showed a higher sensitivity at low concentration and a lower limit of detection when compared to a free dye assay. Assays performed with freeze dried αNPs after 4 and 22 days also showed good reproducibility. PMID:26092116

  5. Resonance energy transfer-amplifying fluorescence quenching at the surface of silica nanoparticles toward ultrasensitive detection of TNT.

    PubMed

    Gao, Daming; Wang, Zhenyang; Liu, Bianhua; Ni, Lin; Wu, Minghong; Zhang, Zhongping

    2008-11-15

    This paper reports a resonance energy transfer-amplifying fluorescence quenching at the surface of silica nanoparticles for the ultrasensitive detection of 2,4,6-trinitrotoluene (TNT) in solution and vapor environments. Fluorescence dye and organic amine were covalently modified onto the surface of silica nanoparticles to form a hybrid monolayer of dye fluorophores and amine ligands. The fluorescent silica particles can specifically bind TNT species by the charge-transfer complexing interaction between electron-rich amine ligands and electron-deficient aromatic rings. The resultant TNT-amine complexes bound at the silica surface can strongly suppress the fluorescence emission of the chosen dye by the fluorescence resonance energy transfer (FRET) from dye donor to the irradiative TNT-amine acceptor through intermolecular polar-polar interactions at spatial proximity. The quenching efficiency of the hybrid nanoparticles with TNT is greatly amplified by at least 10-fold that of the corresponding pure dye. The nanoparticle-assembled arrays on silicon wafer can sensitively detect down to approximately 1 nM TNT with the use of only 10 microL of solution (approximately 2 pg TNT) and several ppb of TNT vapor in air. The simple FRET-based nanoparticle sensors reported here exhibit a high and stable fluorescence brightness, strong analyte affinity, and good assembly flexibility and can thus find many applications in the detection of ultratrace analytes. PMID:18847285

  6. Functionalized silica nanoparticles: a platform for fluorescence imaging at the cell and small animal levels.

    PubMed

    Wang, Kemin; He, Xiaoxiao; Yang, XiaoHai; Shi, Hui

    2013-07-16

    Going in vivo, including living cells and the whole body, is very important for gaining a better understanding of the mystery of life and requires specialized imaging techniques. The diversity, composition, and temporal-spatial variation of life activities from cells to the whole body require the analysis techniques to be fast-response, noninvasive, highly sensitive, and stable, in situ and in real-time. Functionalized nanoparticle-based fluorescence imaging techniques have the potential to meet such needs through real-time and noninvasive visualization of biological events in vivo. Functionalized silica nanoparticles (SiNPs) doped with fluorescent dyes appear to be an ideal and flexible platform for developing fluorescence imaging techniques used in living cells and the whole body. We can select and incorporate different dyes inside the silica matrix either noncovalently or covalently. These form the functionalized hybrid SiNPs, which support multiplex labeling and ratiometric sensing in living systems. Since the silica matrix protects dyes from outside quenching and degrading factors, this enhances the photostability and biocompatibility of the SiNP-based probes. This makes them ideal for real-time and long-time tracking. One nanoparticle can encapsulate large numbers of dye molecules, which amplifies their optical signal and temporal-spatial resolution response. Integrating fluorescent dye-doped SiNPs with targeting ligands using various surface modification techniques can greatly improve selective recognition. Along with the endocytosis, functionalized SiNPs can be efficiently internalized into cells for noninvasive localization, assessment, and monitoring. These unique characteristics of functionalized SiNPs substantially support their applications in fluorescence imaging in vivo. In this Account, we summarize our efforts to develop functionalized dye-doped SiNPs for fluorescence imaging at the cell and small animal levels. We first discuss how to design and

  7. Use of fluorescent NIR dyes in silica nanoparticles and as enzyme substrates in bioanalytical applications

    NASA Astrophysics Data System (ADS)

    Patonay, Gabor; Chapman, Gala; Beckford, Garfield; Henary, Maged; Ellis, Holly

    2014-03-01

    Near-Infrared (NIR) absorbing carbocyanine dyes have been increasingly used in analytical, biological and medical fields as they can be useful for developing bioanalytical and biomedical methods. The utilization of the NIR spectral region (650-900 nm) is advantageous and is due to the inherently lower background interference and the high molar absorptivities of NIR chromophores. NIR dyes typically have relatively lower fluorescent quantum yield as compared to visible fluorophores, but much higher molar absorptivities which more than compensates for the lower quantum yields regarding detection limits. Fluorescence intensity of NIR dyes significantly increases by enclosing several dye molecules in silica nanoparticles. Self quenching may become a problem for carbocyanines at such high concentrations that may be present in the silica nanoparticles. Dyes that have large Stokes' shift can significantly decrease this problem. Increased Stokes' shift for carbocyanines dyes can be achieved by substituting meso position halogens with a linker containing aliphatic or aromatic amino moiety which also serves as a covalent linker for attaching the dye molecule to the nanoparticle backbone. The primary applications of these particles are for bright fluorescent labels to be used in bioanalytical applications such as immunochemistry, flow cytometry, etc. This work also discusses the use of NIR dyes as enzyme substrates. NIR dyes can be used as enzyme substrates and hence for characterization of enzyme activity. The well characterized alkenesulfonate monooxygenase enzyme was chosen for these studies. Carbocyanines containing alkylsulfonate moieties do not exhibit significant fluorescence change upon binding to biomolecules however otherwise identical NIR dye analogs that contain alkylaldehyde moiety at the same position do exhibit changes which can be utilized for characterization of alkenesulfonate monooxygenase enzyme activity using near infrared dyes as substrates. In this study

  8. Composite silica coated gold nanosphere and quantum dots nanoparticles for X-ray CT and fluorescence bimodal imaging.

    PubMed

    Song, Ji-Tao; Yang, Xiao-Quan; Zhang, Xiao-Shuai; Yan, Dong-Mei; Yao, Ming-Hao; Qin, Meng-Yao; Zhao, Yuan-Di

    2015-07-01

    In this study, silica coated Au nanospheres (Au@SiO2) were prepared by a reverse microemulsion method; subsequently, a layer of fluorescent quantum dots (QDs) were adsorbed onto it and then it was coated with silica again. After modifying with PVP, the composite silica coated gold nanosphere and quantum dots nanoparticle (Au@SiO2-QDs/SiO2-PVP) was obtained. This composite structure contained Au and QDs, and it could be used for contrast-enhanced X-ray CT imaging and fluorescence imaging. Characterization showed that the composite nanoparticle had good dispersity, a high fluorescence intensity and a good effect of X-ray absorption, and it was suitable for using as a bimodal imaging probe. PMID:26008798

  9. Development of highly fluorescent silica nanoparticles chemically doped with organic dye for sensitive DNA microarray detection.

    PubMed

    Liu, Aihua; Wu, Liyou; He, Zhili; Zhou, Jizhong

    2011-10-01

    Increasing the sensitivity in DNA microarray hybridization can significantly enhance the capability of microarray technology for a wide range of research and clinical diagnostic applications, especially for those with limited sample biomass. To address this issue, using reverse microemulsion method and surface chemistry, a novel class of homogenous, photostable, highly fluorescent streptavidin-functionalized silica nanoparticles was developed, in which Alexa Fluor 647 (AF647) molecules were covalently embedded. The coating of bovine serum albumin on the resultant fluorescent particles can greatly eliminate nonspecific background signal interference. The thus-synthesized fluorescent nanoparticles can specifically recognize biotin-labeled target DNA hybridized to the microarray via streptavidin-biotin interaction. The response of this DNA microarray technology exhibited a linear range within 0.2 to 10 pM complementary DNA and limit of detection of 0.1 pM, enhancing microarray hybridization sensitivity over tenfold. This promising technology may be potentially applied to other binding events such as specific interactions between proteins. PMID:21822973

  10. Synthesis and characterization of fluorescence-labelled silica core-shell and noble metal-decorated ceria nanoparticles

    PubMed Central

    Rennhak, Markus; Reller, Armin

    2014-01-01

    Summary The present review article covers work done in the cluster NPBIOMEM in the DFG priority programme SPP 1313 and focuses on synthesis and characterization of fluorescent silica and ceria nanoparticles. Synthetic methods for labelling of silica and polyorganosiloxane/silica core–shell nanoparticles with perylenediimide derivatives are described, as well as the modification of the shell with thiol groups. Photometric methods for the determination of the number of thiol groups and an estimate for the number of fluorescent molecules per nanoparticles, including a scattering correction, have been developed. Ceria nanoparticles decorated with noble metals (Pt, Pd, Rh) are models for the decomposition products of automobile catalytic converters which appear in the exhaust gases and finally interact with biological systems including humans. The control of the degree of agglomeration of small ceria nanoparticles is the basis for their synthesis. Almost monodisperse agglomerates (40 ± 4–260 ± 40 nm diameter) can be prepared and decorated with noble metal nanoparticles (2–5 nm diameter). Fluorescence labelling with ATTO 647N gave the model particles which are now under biophysical investigation. PMID:25671137

  11. Goat anti-rabbit IgG conjugated fluorescent dye-doped silica nanoparticles for human breast carcinoma cell recognition.

    PubMed

    Chen, Min-Yan; Chen, Ze-Zhong; Wu, Ling-Ling; Tang, Hong-Wu; Pang, Dai-Wen

    2013-11-12

    We report an indirect method for cancer cell recognition using photostable fluorescent silica nanoprobes as biological labels. The dye-doped fluorescent silica nanoparticles were synthesized using the water-in-oil (W/O) reverse microemulsion method. The silica matrix was produced by the controlled hydrolysis of tetraethylorthosilicate (TEOS) in water nanodroplets with the initiation of ammonia (NH3·H2O). Fluorescein isothiocyanate (FITC) or rhodamine B isothiocyanate conjugated with dextran (RBITC-Dextran) was doped in silica nanoparticles (NPs) with a size of 60 ± 5 nm as a fluorescent signal element by covalent bonding and steric hindrance, respectively. The secondary antibody, goat anti-rabbit IgG, was conjugated on the surface of the PEG-terminated modified FITC-doped or RBITC-Dextran-doped silica nanoparticles (PFSiNPs or PBSiNPs) by covalent binding to the PEG linkers using the cyanogen bromide method. The concentrations of goat anti-rabbit IgG covering the nanoprobes were quantified via the Bradford method. In the proof-of-concept experiment, an epithelial cell adhesion molecule (EpCAM) on the human breast cancer SK-Br-3 cell surface was used as the tumor marker, and the nanoparticle functionalized with rabbit anti-EpCAM antibody was employed as the nanoprobe for cancer cell recognition. Compared with fluorescent dye labeled IgG (FITC-IgG and RBITC-IgG), the designed nanoprobes display dramatically increased stability of fluorescence as well as photostability under continuous irradiation. PMID:24179992

  12. Layer-by-layer engineering fluorescent polyelectrolyte coated mesoporous silica nanoparticles as pH-sensitive nanocarriers for controlled release

    NASA Astrophysics Data System (ADS)

    Du, Pengcheng; Zhao, Xubo; Zeng, Jin; Guo, Jinshan; Liu, Peng

    2015-08-01

    Fluorescent core/shell composite has been fabricated by the layer-by-layer (LbL) assembly of the fluorescein isothiocyanate modified chitosan (CS-FITC) and sodium alginate (AL) onto the carboxyl modified mesoporous silica nanoparticles (MSN-COOH), followed by PEGylation. It exhibits stability in high salt-concentration media and the pH responsive fluorescent feature can be used for cell imaging. Furthermore, the modified MSN cores can enhance the DOX loading capacity and the multifunctional polyelectrolyte shell can adjust the drug release upon the media pH, showing a low leakage quantity at the neutral environment but significantly enhanced release at lower pH media mimicking the tumor environments. Therefore, the biocompatible fluorescent polyelectrolyte coated mesoporous silica nanoparticles (MSN-LBL-PEG) offer promise for tumor therapy.

  13. Iodinated oil-loaded, fluorescent mesoporous silica-coated iron oxide nanoparticles for magnetic resonance imaging/computed tomography/fluorescence trimodal imaging.

    PubMed

    Xue, Sihan; Wang, Yao; Wang, Mengxing; Zhang, Lu; Du, Xiaoxia; Gu, Hongchen; Zhang, Chunfu

    2014-01-01

    In this study, a novel magnetic resonance imaging (MRI)/computed tomography (CT)/fluorescence trifunctional probe was prepared by loading iodinated oil into fluorescent mesoporous silica-coated superparamagnetic iron oxide nanoparticles (i-fmSiO4@SPIONs). Fluorescent mesoporous silica-coated superparamagnetic iron oxide nanoparticles (fmSiO4@SPIONs) were prepared by growing fluorescent dye-doped silica onto superparamagnetic iron oxide nanoparticles (SPIONs) directed by a cetyltrimethylammonium bromide template. As prepared, fmSiO4@SPIONs had a uniform size, a large surface area, and a large pore volume, which demonstrated high efficiency for iodinated oil loading. Iodinated oil loading did not change the sizes of fmSiO4@SPIONs, but they reduced the MRI T2 relaxivity (r2) markedly. I-fmSiO4@SPIONs were stable in their physical condition and did not demonstrate cytotoxic effects under the conditions investigated. In vitro studies indicated that the contrast enhancement of MRI and CT, and the fluorescence signal intensity of i-fmSiO4@SPION aqueous suspensions and macrophages, were intensified with increased i-fmSiO4@SPION concentrations in suspension and cell culture media. Moreover, for the in vivo study, the accumulation of i-fmSiO4@SPIONs in the liver could also be detected by MRI, CT, and fluorescence imaging. Our study demonstrated that i-fmSiO4@SPIONs had great potential for MRI/CT/fluorescence trimodal imaging. PMID:24904212

  14. Iodinated oil-loaded, fluorescent mesoporous silica-coated iron oxide nanoparticles for magnetic resonance imaging/computed tomography/fluorescence trimodal imaging

    PubMed Central

    Xue, Sihan; Wang, Yao; Wang, Mengxing; Zhang, Lu; Du, Xiaoxia; Gu, Hongchen; Zhang, Chunfu

    2014-01-01

    In this study, a novel magnetic resonance imaging (MRI)/computed tomography (CT)/fluorescence trifunctional probe was prepared by loading iodinated oil into fluorescent mesoporous silica-coated superparamagnetic iron oxide nanoparticles (i-fmSiO4@SPIONs). Fluorescent mesoporous silica-coated superparamagnetic iron oxide nanoparticles (fmSiO4@SPIONs) were prepared by growing fluorescent dye-doped silica onto superparamagnetic iron oxide nanoparticles (SPIONs) directed by a cetyltrimethylammonium bromide template. As prepared, fmSiO4@SPIONs had a uniform size, a large surface area, and a large pore volume, which demonstrated high efficiency for iodinated oil loading. Iodinated oil loading did not change the sizes of fmSiO4@SPIONs, but they reduced the MRI T2 relaxivity (r2) markedly. I-fmSiO4@SPIONs were stable in their physical condition and did not demonstrate cytotoxic effects under the conditions investigated. In vitro studies indicated that the contrast enhancement of MRI and CT, and the fluorescence signal intensity of i-fmSiO4@SPION aqueous suspensions and macrophages, were intensified with increased i-fmSiO4@SPION concentrations in suspension and cell culture media. Moreover, for the in vivo study, the accumulation of i-fmSiO4@SPIONs in the liver could also be detected by MRI, CT, and fluorescence imaging. Our study demonstrated that i-fmSiO4@SPIONs had great potential for MRI/CT/fluorescence trimodal imaging. PMID:24904212

  15. Hybrid silica-gold core-shell nanoparticles for fluorescence enhancement

    NASA Astrophysics Data System (ADS)

    Grzelak, J.; Krajewska, A.; Krajnik, B.; Jamiola, D.; Choma, J.; Jankiewicz, B.; Piątkowski, D.; Nyga, P.; Mackowski, S.

    2016-06-01

    We demonstrate that SiO2 nanoparticles coated with a gold island film (GIF) provide an efficient plasmonic platform for enhancing fluorescence intensity of chlorophyll-containing photosynthetic complexes. Fluorescence images obtained for single SiO2-Au coreshell nanoparticles mixed with photosynthetic complexes reveal very uniform emission patterns of a circular shape, similarly as observed for bare SiO2 nanoparticles. The fluorescence enhancement of chlorophyll emission for SiO2-Au nanostructures is up to four-fold compared to bare SiO2 nanoparticles and shortening of fluorescence decay indicates its plasmonic origin. For doublets or triplets of core-shell SiO2-Au nanoparticles, the intensity of emission is further increased as a result of hot-spot formation at the interfaces of such assemblies.

  16. A highly sensitive and selective fluorescent Cu2+ sensor synthesized with silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Zheng, Jiannan; Xiao, Chuan; Fei, Qiang; Li, Ming; Wang, Baojun; Feng, Guodong; Yu, Hongmei; Huan, Yanfu; Song, Zhiguang

    2010-01-01

    A novel fluorescent nanosensor for the determination of Cu2+ was synthesized with N-(quinoline-8-yl)-2-(3-triethoxysilyl-propylamino)-acetamide (QlOEt) grafted onto the surface of silica nanoparticles (SiNPs) using the reverse microemulsion method. Spherical SiNPs were used as substrate and QlOEt was used simultaneously as the binding and readout system for Cu2+. This sensor has been realized as a highly sensitive and selective technique for the detection and quantification of trace amounts of Cu2+. The probe exhibits a dynamic response range for Cu2+ from 2.0 × 10-6 to 2.0 × 10-5 M, with a detection limit of 3.8 × 10-7 M. Other alkali, alkaline earth, and transitional metal ions including Li+, K+, Mg2+, Ca2+, Sr2+, Mn2+, Zn2+, Mo6+, Pb2+, Ag+ had no significant interference on Cu2+ determination. Poisonous and flammable reagents are avoided during the synthesis of this nanosensor. Therefore the strategy explored in this work can be extended to the synthesis of other chemo- and biosensors for direct detection of specific targets in an intracellular environment.

  17. On the incorporation of Rhodamine B and 2‧,7‧-dichlorofluorescein dyes in silica: Synthesis of fluorescent nanoparticles

    NASA Astrophysics Data System (ADS)

    Gomes, Elis C. C.; de Carvalho, Idalina M. M.; Diógenes, Izaura C. N.; de Sousa, Eduardo H. S.; Longhinotti, Elisane

    2014-05-01

    The present paper reports the incorporation of 2‧,7‧-dichlorofluorescein (DCF) and Rhodamine B (RhB) dyes in silica nanoparticles by using the Stöber's method with some modifications. Based on infrared and electronic spectroscopies, these dyes were successfully incorporated resulting in fluorescent nanomaterials of an average size of 80 nm. A composite fluorescent nanomaterial containing both dyes was also synthesized and showed the occurrence of Förster resonant energy transfer process (FRET) with the average distance between the donor (DCF) and acceptor (RhB) of 3.6 nm. Furthermore, these fluorescent nanoparticles were modified with folic acid producing nanomaterials whose Zeta potential values were in the range of -2 to -13 mV. These values are consistent with the low dispersivity observed by TEM micrographs. Altogether, these suitable properties can lead to the development of nanomaterials for cancer bioimaging and drug release.

  18. A novel fluorescent aptasensor based on gold and silica nanoparticles for the ultrasensitive detection of ochratoxin A

    NASA Astrophysics Data System (ADS)

    Taghdisi, Seyed Mohammad; Danesh, Noor Mohammad; Beheshti, Hamed Reza; Ramezani, Mohammad; Abnous, Khalil

    2016-02-01

    Analytical approaches for the detection and quantitation of ochratoxin A (OTA) in blood serum and food products are high in demand. In this study, a fluorescent aptamer-based sensor (aptasensor) is developed for the selective and sensitive detection of OTA, based on a complementary strand of aptamer (CS) and two types of nanoparticles, gold nanoparticles (AuNPs) and silica nanoparticles (SNPs) coated with streptavidin. The fabricated aptasensor inherits the characteristics of SNPs, as enhancers of fluorescence intensity; AuNPs, such as large surface area and unique optical properties; and high affinity of the aptamer toward its target compared to its CS. In the absence of OTA, no FAM and biotin-labeled CS is in the environment of the SNPs coated with streptavidin, which leads to no fluorescence emission. In the presence of the target, an FAM and biotin-labeled CS-SNPs coated with streptavidin conjugate is formed, thus resulting in a very strong fluorescence emission. The designed fluorescent aptasensor exhibits high selectivity toward OTA with a limit of detection (LOD) as low as 0.098 nM. Furthermore, the fabricated aptasensor was successfully applied for the detection of OTA in grape juice and serum with LODs of 0.113 and 0.152 nM, respectively.

  19. Fluorescent magnetic nanoparticles for cell labeling: flux synthesis of manganite particles and novel functionalization of silica shell.

    PubMed

    Kačenka, Michal; Kaman, Ondřej; Kikerlová, Soňa; Pavlů, Barbora; Jirák, Zdeněk; Jirák, Daniel; Herynek, Vít; Černý, Jan; Chaput, Frédéric; Laurent, Sophie; Lukeš, Ivan

    2015-06-01

    Novel synthetic approaches for the development of multimodal imaging agents with high chemical stability are demonstrated. The magnetic cores are based on La0.63Sr0.37MnO3 manganite prepared as individual grains using a flux method followed by additional thermal treatment in a protective silica shell allowing to enhance their magnetic properties. The cores are then isolated and covered de novo with a hybrid silica layer formed through the hydrolysis and polycondensation of tetraethoxysilane and a fluorescent silane synthesized from rhodamine, piperazine spacer, and 3-iodopropyltrimethoxysilane. The aminoalkyltrialkoxysilanes are strictly avoided and the resulting particles are hydrolytically stable and do not release dye. The high colloidal stability of the material and the long durability of the fluorescence are reinforced by an additional silica layer on the surface of the particles. Structural and magnetic studies of the products using XRD, TEM, and SQUID magnetometry confirm the importance of the thermal treatment and demonstrate that no mechanical treatment is required for the flux-synthesized manganite. Detailed cell viability tests show negligible or very low toxicity at concentrations at which excellent labeling is achieved. Predominant localization of nanoparticles in lysosomes is confirmed by immunofluorescence staining. Relaxometric and biological studies suggest that the functionalized nanoparticles are suitable for imaging applications. PMID:25702866

  20. A Fluorescent Sensor Synthesized Using Silica Nanoparticles for Detecting Hg²⁺ in Aqueous Solution.

    PubMed

    Zhao, Wenqi; Liu, Xingliang; Lv, Haitang; Fu, Hua; Huang, Ziping; Han, Aixia

    2016-01-01

    With the aim of detecting Hg²⁺ in aqueous solution, a new fluorescent nanosensor (RhB-APTES-SiNPs) for the determination of Hg²⁺ has been successfully developed. This senor was synthesized by immobilizing RhB-APTES on the surface of silica nanoparticles (SiNPs), which were prepared using the reverse microemulsion method. RhB-APTES-SiNPs can detect Hg²⁺ on-line, in real time and with the naked eye, thus providing "turn-on" fluorescence enhancement. The developed nanosensor exhibits highly sensitivity and selectivity over several cations in aqueous solution. Additionally, RhB-APTES-SiNPs exhibits an excellent ability to detect Hg²⁺ within a linear range from 1 to 6 µM, and its detection limit was calculated to be 0.5 ppb. PMID:27398518

  1. Cyclodextrin-clicked silica/CdTe fluorescent nanoparticles for enantioselective recognition of amino acids

    NASA Astrophysics Data System (ADS)

    Zhou, Jie; Liu, Yun; Zhang, Zhixing; Yang, Sha; Tang, Jian; Liu, Wei; Tang, Weihua

    2016-03-01

    Fluorescent sensors based on semiconductor quantum dots (QDs) have been immensely investigated for achiral molecular recognition. For chiral discrimination of amino acids (AAs), we herein report a versatile fluorescent sensor, i.e., CdTe QDs encapsulated with cyclodextrin (CD) clicked silica via layer-by-layer modification. The as-obtained hybrid molecular recognition platform exhibited excellent chirality sensing of AAs at micromolar concentrations in water. By taking advantage of the inclusion complexation of CD and the optical properties of the QD core, chiral discrimination was realized on the basis of the different binding energies of the CD-AA enantiomer complexes, as revealed using density-functional theory calculation. The fluorescent probe exhibited linearly enhanced photoluminescence with increased concentration of d-histidine at 0-60 μM and l-histidine at 0-20 μM. These water-soluble fluorescent sensors using a chiral host with a covalently linked chromophore may find applications in the robust sensing of a wide range of achiral and chiral molecules in water.Fluorescent sensors based on semiconductor quantum dots (QDs) have been immensely investigated for achiral molecular recognition. For chiral discrimination of amino acids (AAs), we herein report a versatile fluorescent sensor, i.e., CdTe QDs encapsulated with cyclodextrin (CD) clicked silica via layer-by-layer modification. The as-obtained hybrid molecular recognition platform exhibited excellent chirality sensing of AAs at micromolar concentrations in water. By taking advantage of the inclusion complexation of CD and the optical properties of the QD core, chiral discrimination was realized on the basis of the different binding energies of the CD-AA enantiomer complexes, as revealed using density-functional theory calculation. The fluorescent probe exhibited linearly enhanced photoluminescence with increased concentration of d-histidine at 0-60 μM and l-histidine at 0-20 μM. These water

  2. Cyclodextrin-clicked silica/CdTe fluorescent nanoparticles for enantioselective recognition of amino acids.

    PubMed

    Zhou, Jie; Liu, Yun; Zhang, Zhixing; Yang, Sha; Tang, Jian; Liu, Wei; Tang, Weihua

    2016-03-14

    Fluorescent sensors based on semiconductor quantum dots (QDs) have been immensely investigated for achiral molecular recognition. For chiral discrimination of amino acids (AAs), we herein report a versatile fluorescent sensor, i.e., CdTe QDs encapsulated with cyclodextrin (CD) clicked silica via layer-by-layer modification. The as-obtained hybrid molecular recognition platform exhibited excellent chirality sensing of AAs at micromolar concentrations in water. By taking advantage of the inclusion complexation of CD and the optical properties of the QD core, chiral discrimination was realized on the basis of the different binding energies of the CD-AA enantiomer complexes, as revealed using density-functional theory calculation. The fluorescent probe exhibited linearly enhanced photoluminescence with increased concentration of d-histidine at 0-60 μM and L-histidine at 0-20 μM. These water-soluble fluorescent sensors using a chiral host with a covalently linked chromophore may find applications in the robust sensing of a wide range of achiral and chiral molecules in water. PMID:26893164

  3. High MRI performance fluorescent mesoporous silica-coated magnetic nanoparticles for tracking neural progenitor cells in an ischemic mouse model

    NASA Astrophysics Data System (ADS)

    Zhang, Lu; Wang, Yao; Tang, Yaohui; Jiao, Zheng; Xie, Chengying; Zhang, Haijiao; Gu, Ping; Wei, Xunbin; Yang, Guo-Yuan; Gu, Hongchen; Zhang, Chunfu

    2013-05-01

    Multifunctional probes with high MRI sensitivity and high efficiency for cell labeling are desirable for MR cell imaging. Herein, we have fabricated fluorescent mesoporous silica-coated superparamagnetic iron oxide nanoparticles (fmSiO4@SPIONs) for neural progenitor cell (C17.2) MR imaging. FmSiO4@SPIONs were discrete and uniform in size, and had a clear core-shell structure. The magnetic core size was about 10 nm and the fluorescent mesoporous silica coating layer was around 20 nm. Compared with fluorescent dense silica-coated SPIONs (fdSiO4@SPIONs) with a similar size, fmSiO4@SPIONs demonstrated higher MR sensitivity and cell labeling efficiency. When implanted into the right hemisphere of stroke mice, contralateral to the ischemic territory, a small amount of labeled cells were able to be tracked migrating to the lesion sites using a clinical MRI scanner (3 T). More impressively, even when administered intravenously, the labeled cells could also be monitored homing to the ischemic area. MRI observations were corroborated by histological studies of the brain tissues. Our study demonstrated that fmSiO4@SPIONs are highly effective for cell imaging and hold great promise for MRI cell tracking in future.Multifunctional probes with high MRI sensitivity and high efficiency for cell labeling are desirable for MR cell imaging. Herein, we have fabricated fluorescent mesoporous silica-coated superparamagnetic iron oxide nanoparticles (fmSiO4@SPIONs) for neural progenitor cell (C17.2) MR imaging. FmSiO4@SPIONs were discrete and uniform in size, and had a clear core-shell structure. The magnetic core size was about 10 nm and the fluorescent mesoporous silica coating layer was around 20 nm. Compared with fluorescent dense silica-coated SPIONs (fdSiO4@SPIONs) with a similar size, fmSiO4@SPIONs demonstrated higher MR sensitivity and cell labeling efficiency. When implanted into the right hemisphere of stroke mice, contralateral to the ischemic territory, a small amount of

  4. A DNA hybridization detection based on fluorescence resonance energy transfer between dye-doped core-shell silica nanoparticles and gold nanoparticles.

    PubMed

    Gao, Feng; Cui, Peng; Chen, Xiaoxiao; Ye, Qingqing; Li, Maoguo; Wang, Lun

    2011-10-01

    A novel and efficient method to evaluate the DNA hybridization based on a fluorescence resonance energy transfer (FRET) system, with fluorescein isothiocyanate (FITC)-doped fluorescent silica nanoparticles (SiNPs) as donor and gold nanoparticles (AuNPs) as acceptor, has been reported. The strategy for specific DNA sequence detecting is based on DNA hybridization event, which is detected via excitation of SiNPs-oligonucleotide conjugates and energy transfer to AuNPs-oligonucleotide conjugates. The proximity required for FRET arises when the SiNPs-oligonucleotide conjugates hybridize with partly complementary AuNPs-oligonucleotide conjugates, resulting in the fluorescence quenching of donors, SiNPs-oligonucleotide conjugates, and the formation of a weakly fluorescent complex, SiNPs-dsDNA-AuNPs. Upon the addition of the target DNA sequence to SiNPs-dsDNA-AuNPs complex, the fluorescence restores (turn-on). Based on the restored fluorescence, a homogeneous assay for the target DNA is proposed. Our results have shown that the linear range for target DNA detection is 0-35.0 nM with a detection limit (3σ) of 3.0 picomole. Compared with FITC-dsDNA-AuNPs probe system, the sensitivity of the proposed probe system for target DNA detection is increased by a factor of 3.4-fold. PMID:21845282

  5. Functional Tomographic Fluorescence Imaging of pH Microenvironments in Microbial Biofilms by Use of Silica Nanoparticle Sensors▿ †

    PubMed Central

    Hidalgo, Gabriela; Burns, Andrew; Herz, Erik; Hay, Anthony G.; Houston, Paul L.; Wiesner, Ulrich; Lion, Leonard W.

    2009-01-01

    Attached bacterial communities can generate three-dimensional (3D) physicochemical gradients that create microenvironments where local conditions are substantially different from those in the surrounding solution. Given their ubiquity in nature and their impacts on issues ranging from water quality to human health, better tools for understanding biofilms and the gradients they create are needed. Here we demonstrate the use of functional tomographic imaging via confocal fluorescence microscopy of ratiometric core-shell silica nanoparticle sensors (C dot sensors) to study the morphology and temporal evolution of pH microenvironments in axenic Escherichia coli PHL628 and mixed-culture wastewater biofilms. Testing of 70-, 30-, and 10-nm-diameter sensor particles reveals a critical size for homogeneous biofilm staining, with only the 10-nm-diameter particles capable of successfully generating high-resolution maps of biofilm pH and distinct local heterogeneities. Our measurements revealed pH values that ranged from 5 to >7, confirming the heterogeneity of the pH profiles within these biofilms. pH was also analyzed following glucose addition to both suspended and attached cultures. In both cases, the pH became more acidic, likely due to glucose metabolism causing the release of tricarboxylic acid cycle acids and CO2. These studies demonstrate that the combination of 3D functional fluorescence imaging with well-designed nanoparticle sensors provides a powerful tool for in situ characterization of chemical microenvironments in complex biofilms. PMID:19801466

  6. Fungus-Mediated Preferential Bioleaching of Waste Material Such as Fly - Ash as a Means of Producing Extracellular, Protein Capped, Fluorescent and Water Soluble Silica Nanoparticles

    PubMed Central

    Khan, Shadab Ali; Uddin, Imran; Moeez, Sana; Ahmad, Absar

    2014-01-01

    In this paper, we for the first time show the ability of the mesophilic fungus Fusarium oxysporum in the bioleaching of waste material such as Fly-ash for the extracellular production of highly crystalline and highly stable, protein capped, fluorescent and water soluble silica nanoparticles at ambient conditions. When the fungus Fusarium oxysporum is exposed to Fly-ash, it is capable of selectively leaching out silica nanoparticles of quasi-spherical morphology within 24 h of reaction. These silica nanoparticles have been completely characterized by UV-vis spectroscopy, Photoluminescence (PL), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Energy dispersive analysis of X-rays (EDAX). PMID:25244567

  7. Fungus-mediated preferential bioleaching of waste material such as fly - ash as a means of producing extracellular, protein capped, fluorescent and water soluble silica nanoparticles.

    PubMed

    Khan, Shadab Ali; Uddin, Imran; Moeez, Sana; Ahmad, Absar

    2014-01-01

    In this paper, we for the first time show the ability of the mesophilic fungus Fusarium oxysporum in the bioleaching of waste material such as Fly-ash for the extracellular production of highly crystalline and highly stable, protein capped, fluorescent and water soluble silica nanoparticles at ambient conditions. When the fungus Fusarium oxysporum is exposed to Fly-ash, it is capable of selectively leaching out silica nanoparticles of quasi-spherical morphology within 24 h of reaction. These silica nanoparticles have been completely characterized by UV-vis spectroscopy, Photoluminescence (PL), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Energy dispersive analysis of X-rays (EDAX). PMID:25244567

  8. Magnetic bead-based fluorescence immunoassay for aflatoxin B1 in food using biofunctionalized rhodamine B-doped silica nanoparticles.

    PubMed

    Tang, Dianping; Yu, Yongliang; Niessner, Reinhard; Miró, Manuel; Knopp, Dietmar

    2010-10-01

    A simple and sensitive fluorescence immunoassay for the detection of aflatoxin B(1) (AFB(1), as a model compound) in food was developed using AFB(1)-bovine serum albumin conjugate (AFB(1)-BSA)-functionalized magnetic beads as immunosensing probes. The recognition elements were prepared by doping of rhodamine B (RB) fluorophore into silica nanoparticles followed by immobilization of monoclonal anti-AFB(1) antibodies on the silica shell. Based on a competitive-type immunoassay format, the assay was performed both in low-binding polypropylene 96-well microtiter plates (MTPs) and in an automated sequential injection (SI) format. Similar detection limit (LOD) of 0.2 ng mL(-1)vs. 0.1 ng mL(-1) but narrower dynamic working linear range of 0.5-7 ng mL(-1)vs. 0.5-30 ng mL(-1) was obtained toward AFB(1) standards with the flow setup compared to the MTP format. Intra-batch assay precision was substantially improved (≤5.3% vs.≤8.7%) by resorting to the SI manifold. The proposed method features unbiased identification of negative (blank) and positive samples. No significant differences at the 95% confidence level were encountered in the analysis of naturally contaminated peanut samples between the proposed immunoassay and liquid chromatography for determination of AFB(1). PMID:20820489

  9. Synthesis and functionalization of silica-based nanoparticles with fluorescent biocompounds extracted from Eysenhardtia polystachya for biological applications.

    PubMed

    Ferreira, Guadalupe; Hernandez-Martinez, Angel R; Pool, Hector; Molina, Gustavo; Cruz-Soto, Martha; Luna-Barcenas, Gabriel; Estevez, Miriam

    2015-12-01

    Several types of dyes or fluorophores are used for the detection of interactions between drug carriers and cells, within biomedicine field. However, many of them have a certain level of toxicity and instability affecting their biological properties. Different studies have demonstrated that nanoparticles (NPs) have interesting properties that could be used to stabilize diverse biomolecules, including dyes. Here, we report the synthesis of a novel nanosystem by the functionalization of silica NPs using biocompounds extracted from Mexican tree "Palo azul" (Eysenhardtia polystachya) and APTES as a coupling agent. Particle size, electrical properties, and morphology of the novel nanosystem were analyzed. The extracted biocompounds presented fluorescence which prevails over time, even after nanosystem formation and apparent cellular internalization. These were detected using MCF-7 cells visualized by confocal laser-scanning microscopy (CLSM), finding that the nanosystem was able to internalize into cells and act as a fluorescent biomarker. By this method, our novel nanosystem opens the possibilities to obtain sensitive data in a noninvasive manner for biological applications, such as early-stage cancer diagnosis, drug delivery, and pathogen detection. PMID:26354239

  10. Synthesis of fluorescent dye-doped silica nanoparticles for target-cell-specific delivery and intracellular microRNA imaging.

    PubMed

    Li, Henan; Mu, Yawen; Qian, Shanshan; Lu, Jusheng; Wan, Yakun; Fu, Guodong; Liu, Songqin

    2015-01-21

    MicroRNA (miRNA) is found to be up-regulated in many kinds of cancer and therefore is classified as an oncomiR. Herein, we design a multifunctional fluorescent nanoprobe (FSiNP-AS/MB) with the AS1411 aptamer and a molecular beacon (MB) co-immobilized on the surface of the fluorescent dye-doped silica nanoparticles (FSiNPs) for target-cell-specific delivery and intracellular miRNA imaging. The FSiNPs were prepared by a facile reverse microemulsion method from tetraethoxysilane and silane derivatized coumarin that was previously synthesized by click chemistry. The as-prepared FSiNPs possess uniform size distribution, good optical stability and biocompatibility. In addition, there is a remarkable affinity interaction between the AS1411 aptamer and the nucleolin protein on the cancer cell surface. Thus, a target-cell-specific delivery system by the FSiNP-AS/MB is proposed for effectively transferring a MB into the cancer cells to recognize the target miRNA. Using miRNA-21 in MCF-7 cells (a human breast cancer cell line) as a model, the proposed multifunctional nanosystems not only allow target-cell-specific delivery with the binding affinity of AS1411, but also can track simultaneously the transfected cells and detect intracellular miRNA in situ. The proposed multifunctional nanosystems are a promising platform for a highly sensitive luminescent nonviral vector in biomedical and clinical research. PMID:25417796

  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 filter effect of both dyes. The decoration of the silica surface by cationic surfactants induces the quenching through the energy transfer between silica coated Tb(III) complexes and dye anions inserted into surfactant aggregates. Thus the distribution of surfactants aggregates at the silica/water interface and in the bulk of solution greatly affects dynamic quenching efficiency. The displacement of dye anions from the interfacial surfactant adlayer by anionic surfactants and phospholipids is accompanied by the "off-on" switching of Tb(III)-centered luminescence. PMID:22209651

  12. Silica nanoparticles for separation of biologically active amines by capillary electrophoresis with laser-induced native fluorescence detection.

    PubMed

    Kuo, I-Ting; Huang, Yu-Fen; Chang, Huan-Tsung

    2005-06-01

    This paper describes the analysis of biologically active amines by capillary electrophoresis (CE) in conjunction with laser-induced native fluorescence detection. In order to simultaneously analyze amines and acids as well as to achieve high sensitivity, 10 mM formic acid solutions (pH < 4.0) containing silica nanoparticles (SiNPs) were chosen as the background electrolytes. With increasing SiNP concentration, the migration times for seven analytes decrease as a result of increase in electroosmotic flow (EOF) and decrease in their electrophoretic mobilities against EOF. A small EOF generated at pH 3.0 reveals adsorption of SiNPs on the deactivated capillary wall. The decreases in electrophoretic mobilities with increasing SiNP concentration up to 0.3x indicate the interactions between the analytes and the SiNPs. Having a great sensitivity (the limits of detection at a signal-to-noise ratio (S/N) = 3 of 0.09 nM for tryptamine (TA)), high efficiency, and excellent reproducibility (less than 2.4% of the migration times), this developed method has been applied to the analysis of urinal samples with the concentrations of 0.50 +/- 0.02 microM, 0.49 +/- 0.04 microM, and 74 +/- 2 microM for TA, 5-hydroxytryptamine, and tryptophan, respectively. The successful examples demonstrated in this study open up a possibility of using functional nanoparticles for the separation of different analytes by CE. PMID:15937981

  13. LaB6 nanoparticles with carbon-doped silica coating for fluorescence imaging and near-IR photothermal therapy of cancer cells.

    PubMed

    Lai, B-H; Chen, D-H

    2013-07-01

    In this study, LaB6 nanoparticles are used as a novel nanomaterial for near-infrared (NIR) photothermal therapy because they are cheaper than nanostructured gold, are easy to prepare and have an excellent NIR photothermal conversion property. Furthermore, the surface of LaB6 nanoparticles is coated with a carbon-doped silica (C-SiO2) shell to introduce a fluorescent property and improve stability and biocompatibility. The resulting LaB6@C-SiO2 nanoparticles retain the excellent NIR photothermal conversion property and exhibit a bright blue emission under UV irradiation or a green emission under visible irradiation. Using a HeLa cancer cell line, it is demonstrated that LaB6@C-SiO2 nanoparticles have no significant cytotoxicity, but their presence leads to remarkable cell death after NIR irradiation. In addition, from the observation of cellular uptake, the fluorescence labeling function of LaB6@SiO2 (LaB6 core/SiO2 shell) nanoparticles is also confirmed. These results suggest that LaB6@C-SiO2 nanoparticles may potentially serve as an efficient multifunctional nano-platform for simultaneous fluorescent imaging and NIR-triggered photothermal therapy of cancer cells. PMID:23542555

  14. Volume labeling with Alexa Fluor dyes and surface functionalization of highly sensitive fluorescent silica (SiO2) nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Nallathamby, Prakash D.; Foster, Carmen M.; Morrell-Falvey, Jennifer L.; Mortensen, Ninell P.; Doktycz, Mitchel J.; Gu, Baohua; Retterer, Scott T.

    2013-10-01

    A new synthesis approach is described that allows the direct incorporation of fluorescent labels into the volume or body of SiO2 nanoparticles. In this process, fluorescent Alexa Fluor dyes with different emission wavelengths were covalently incorporated into the SiO2 nanoparticles during their formation by the hydrolysis of tetraethoxysilane. The dye molecules were homogeneously distributed throughout the SiO2 nanoparticles. The quantum yields of the Alexa Fluor volume-labeled SiO2 nanoparticles were much higher than nanoparticles labeled using conventional organic dyes. The size of the resulting nanoparticles was controlled using microemulsion reaction media with sizes in the range of 20-100 nm and a polydispersity of <15%. In comparison with conventional surface tagged particles created by post-synthesis modification, this process maintains the physical and surface chemical properties that have the most pronounced effect on colloidal stability and interactions with their surroundings. These volume-labeled nanoparticles have proven to be extremely robust, showing excellent signal strength, negligible photobleaching, and minimal loss of functional organic components. The native or ``free'' surface of the volume-labeled particles can be altered to achieve a specific surface functionality without altering fluorescence. Their utility was demonstrated for visualizing the association of surface-modified fluorescent particles with cultured macrophages. Differences in particle agglomeration and cell association were clearly associated with differences in observed nanoparticle toxicity. The capacity to maintain particle fluorescence while making significant changes to surface chemistry makes these particles extremely versatile and useful for studies of particle agglomeration, uptake, and transport in environmental and biological systems.A new synthesis approach is described that allows the direct incorporation of fluorescent labels into the volume or body of SiO2

  15. 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

  16. Synthetic pathways to make nanoparticles fluorescent

    NASA Astrophysics Data System (ADS)

    Sokolova, Viktoriya; Epple, Matthias

    2011-05-01

    In biosciences, it is often necessary to follow the pathway of nanoparticles within cells or tissues. The nanoparticles can be used as labeled sensors which may, e.g., address functionalities within a cell, carry other specific agents like drugs or be magnetic for tumor thermotherapy. In the context of nanotoxicology, the fate of a given nanoparticle is of interest. As many methods in cell biology are based on fluorescence detection, there is a strong demand to make nanoparticles fluorescent. Different ways to introduce fluorescence are reviewed and exemplified with typical kinds of nanoparticles, i.e. polymers, silica and calcium phosphate.

  17. Metal enhanced fluorescence with gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Mattingly, Shaina LaRissa Strating

    A novel hybrid nanocomposite of Au nanoparticle-modified silicon nanowire was developed for surface enhanced fluorescence applications. The designed nanocomposite contained a silicon nanowire, gold nanoparticles and a silica layer doped with dye molecules. The hybrid nanomaterial was characterized using scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), fluorescence measurements, Fourier transform infrared (FT-IR) spectroscopy, and energy-dispersive X-ray spectroscopy (EDS). The results showed that the gold nanoparticles were uniformly adhered on the silicon nanowires and covered by a thin silica layer. The nanostructure exhibited strong capacity for surface enhanced fluorescence. Different enhancement factors were obtained by changing synthetic conditions. The second goal of the project was to determine if the shape of gold nanoparticles affects the extent of its fluorescence enhancement under constant external factors. Two shapes of gold nanoparticles were synthesized and characterized by SEM, STEM, zeta potential and absorbance measurements. Then they were coated with fluorescent dye-doped silica and the fluorescence intensity was measured and compared to the pure fluorescent dye. Gold nanorods enhanced fluorescence more than gold nanostars and that the fluorescent dye Alexafluor 700 showed a greater fluorescence intensity change in the presence of nanoparticles than methylene blue.

  18. Near-Infrared Light and pH-Responsive Polypyrrole@Polyacrylic acid/Fluorescent Mesoporous Silica Nanoparticles for Imaging and Chemo-Photothermal Cancer Therapy.

    PubMed

    Zhang, Manjie; Wang, Tingting; Zhang, Lingyu; Li, Lu; Wang, Chungang

    2015-11-01

    We have rationally designed a new theranostic agent by coating near-infrared (NIR) light-absorbing polypyrrole (PPY) with poly(acrylic acid) (PAA), in which PAA acts as a nanoreactor and template, followed by growing small fluorescent silica nanoparticles (fSiO2 NPs) inside the PAA networks, resulting in the formation of polypyrrole@polyacrylic acid/fluorescent mesoporous silica (PPY@PAA/fmSiO2 ) core-shell NPs. Meanwhile, DOX-loaded PPY@PAA/fmSiO2 NPs as pH and NIR dual-sensitive drug delivery vehicles were employed for fluorescence imaging and chemo-photothermal synergetic therapy in vitro and in vivo. The results demonstrate that the PPY@PAA/fmSiO2 NPs show high in vivo tumor uptake by the enhanced permeability and retention (EPR) effect after intravenous injection as revealed by in vivo fluorescence imaging, which is very helpful for visualizing the location of the tumor. Moreover, the obtained NPs inhibit tumor growth (95.6 % of tumors were eliminated) because of the combination of chemo-photothermal therapy, which offers a synergistically improved therapeutic outcome compared with the use of either therapy alone. Therefore, the present study provides new insights into developing NIR and pH-stimuli responsive PPY-based multifunctional platform for cancer theranostics. PMID:26494031

  19. Fluorescent intensity-based differential counting of FITC-doped silica nanoparticles: applications of CD4+ T-cell detection in microchip-type flowcytometers

    NASA Astrophysics Data System (ADS)

    Yun, Hoyoung; Bang, Hyunwoo; Lee, Won Gu; Lim, Hyunchang; Park, Junha; Lee, Joonmo; Riaz, Asif; Cho, Keunchang; Chung, Chanil; Han, Dong-Chul; Chang, Jun Keun

    2007-12-01

    Although CD4+ T-cells are an important target of HIV detection, there have been still major problems in making a diagnosis and monitoring in the third world and the region with few medical facilities. Then, it is necessary to use portable diagnosis devices at low cost when you put an enumeration of CD4+ T-cells. In general, the counting of CD4 below 200cells/uL makes it necessary to initiate antiretroviral treatment in adults (over 13 years old). However, lymphocyte subsets (including CD4 counts) of infants and young children are higher than those of adults. This fact shows the percentage of CD4+ T-cells of blood subsets, i.e., CD4/CD45%, CD4/CD8% or CD4/CD3% means a more reliable indicator of HIV infection than absolute counts in children. To know the percentage of CD4+ T-cell by using two fluorescent dyes of different emission wavelength, at least, one laser and two PMT detectors are in general needed. Then, it is so hard to develop a portable device like a 'toaster size' because this makes such a device more complex including many peripheral modules. In this study, we developed a novel technique to control the intensity of fluorescent dye-doped silica nanoparticles. I synthesized FITC-doped silica nanoparticles conjugated CD4 antibody 10 times brighter than FITC-conjugated CD45 antibody. With the difference of intensity of two fluorescent dyes, we measured two parameters by using only a single detector and laser. Most experiments were achieved with uFACS (microfabricated fluorescence-activated cell sorter) on an inverted microscope (IX71, Olympus). In conclusion, this method enables us to discriminate the difference between CD4 and CD45 in an intensity domain simultaneously. Furthermore, this technique would make it possible develop much cheaper and smaller devices which can count the number of CD4 T-cells.

  20. NIR-responsive silica-coated NaYbF4:Er/Tm/Ho upconversion fluorescent nanoparticles with tunable emission colors and their applications in immunolabeling and fluorescent imaging of cancer cells

    PubMed Central

    Wang, Meng; Mi, Congcong; Zhang, Yixin; Liu, Jinling; Li, Feng; Mao, Chuanbin; Xu, Shukun

    2009-01-01

    NaYbF4: RE upconversion (UC) fluorescent nanoparticles (NPs) were synthesized with variable rare-earth dopants (RE= Er3+, Tm3+, or Ho3+, or a combination of these ions), from rare-earth stearate precursors in a water-ethanol-oleic acid system by using a two-phase solvothermal method. The NPs were shown to emit visible light such as orange, yellow, green, cyan, blue or pink light in response to near infrared (NIR) irradiation, and their emission colors could be simply tuned by changing either the co-dopant concentration or dopant species. The UC NPs were well-dispersed and spherical with an average size of 15~35 nm. They emitted strong UC fluorescence under the 980 nm NIR excitation. The effects of solvothermal reaction time and temperature on nanoparticle size and phase structure as well as UC fluorescence intensity were systematically studied. Water dispersibility was achieved by forming a silica coat on the surface of the UC NPs. After animo-functionalization, the silica-coated UC NPs were chemically conjugated with the rabbit anti-CEA8 antibody and then used as fluorescent biolabels for the immunolabeling and imaging of HeLa cells. The NIR-responsive multicolor visible light emission of these UC NPs will enable potential applications in biolabeling and multiplexed analysis because NIR light can penetrate tissue as deep as several inches and is safe to human body. PMID:20160878

  1. Silica-covered Au nanoresonators for fluorescence modulating of a graphene quantum dot

    NASA Astrophysics Data System (ADS)

    Wang, Su-Feng; He, Da-Wei; Wang, Yong-Sheng; Hu, Yin; Duan, Jia-Hua; Fu, Ming; Wang, Wen-Shuo

    2014-09-01

    We synthesize Au@SiO2 composite particles with a core-shell structure, and utilize the Au@SiO2 nanoparticles to modulate the fluorescence emission of the graphene quantum dot (GQD) through varying the silica shell thickness. The silica shell thickness can be easily controlled by varying the coating time. After silica coating, we investigate the influence of the silica thickness on the fluorescence emission of the GQD and find that the fluorescence property of the GQD can be changed as expected by varying the thickness of the silica shell. We propose an optimized coating time for the silica shell under the interaction of fluorescence quenching and enhancement.

  2. A combination of positive dielectrophoresis driven on-line enrichment and aptamer-fluorescent silica nanoparticle label for rapid and sensitive detection of Staphylococcus aureus.

    PubMed

    Shangguan, Jingfang; Li, Yuhong; He, Dinggeng; He, Xiaoxiao; Wang, Kemin; Zou, Zhen; Shi, Hui

    2015-07-01

    Staphylococcus aureus (S. aureus) is an important human pathogen that causes several diseases ranging from superficial skin infections to life-threatening diseases. Here, a method combining positive dielectrophoresis (pDEP) driven on-line enrichment and aptamer-fluorescent silica nanoparticle label has been developed for the rapid and sensitive detection of S. aureus in microfluidic channels. An aptamer, having high affinity to S. aureus, is used as the molecular recognition tool and immobilized onto chloropropyl functionalized fluorescent silica nanoparticles through a click chemistry approach to obtain S. aureus aptamer-nanoparticle bioconjugates (Apt(S.aureus)/FNPs). The pDEP driven on-line enrichment technology was used for accumulating the Apt(S.aureus)/FNP labeled S. aureus. After incubating with S. aureus, the mixture of Apt(S.aureus)/FNP labeled S. aureus and Apt(S.aureus)/FNPs was directly introduced into the pDEP-based microfluidic system. By applying an AC voltage in a pDEP frequency region, the Apt(S.aureus)/FNP labelled S. aureus moved to the electrodes and accumulated in the electrode gap, while the free Apt(S.aureus)/FNPs flowed away. The signal that came from the Apt(S.aureus)/FNP labelled S. aureus in the focused detection areas was then detected. Profiting from the specificity of aptamer, signal amplification of FNP label and pDEP on-line enrichment, this assay can detect as low as 93 and 270 cfu mL(-1)S. aureus in deionized water and spiked water samples, respectively, with higher sensitivities than our previously reported Apt(S.aureus)/FNP based flow cytometry. Moreover, without the need for separation and washing steps usually required for FNP label involved bioassays, the total assay time including sample pretreatment was within 2 h. PMID:25963028

  3. Aptamer/Graphene Quantum Dots Nanocomposite Capped Fluorescent Mesoporous Silica Nanoparticles for Intracellular Drug Delivery and Real-Time Monitoring of Drug Release.

    PubMed

    Zheng, Fen-Fen; Zhang, Peng-Hui; Xi, Yu; Chen, Jing-Jia; Li, Ling-Ling; Zhu, Jun-Jie

    2015-12-01

    Great challenges in investigating the release of drug in complex cellular microenvironments necessitate the development of stimuli-responsive drug delivery systems with real-time monitoring capability. In this work, a smart drug nanocarrier based on fluorescence resonance energy transfer (FRET) is fabricated by capping graphene quantum dots (GQDs, the acceptor) onto fluorescent mesoporous silica nanoparticles (FMSNs, the donor) via ATP aptamer for real-time monitoring of ATP-triggered drug release. Under extracellular conditions, the fluorescence of FMSNs remains in the "off" state in the low ATP level which is unable to trigger the release of drug. Once specifically recognized and internalized into the target tumor cells by AS1411 aptamer, in the ATP-rich cytoplasm, the conformation switch of the ATP aptamer causes the shedding of the GQDs from the nanocarriers, leading to the release of the loaded drugs and consequently severe cytotoxicity. Simultaneously, the fluorescence of FMSNs turns "on" along with the dissociation of GQDs, which allows real-time monitoring of the release of drug from the pores. Such a drug delivery system features high specificity of dual-target recognition with AS1411 and ATP aptamer as well as high sensitivity of the FRET-based monitoring strategy. Thus, the proposed multifunctional ATP triggered FRET-nanocarriers will find potential applications for versatile drug-release monitoring, efficient drug transport, and targeted cancer therapeutics. PMID:26524192

  4. Optimization of metal-enhanced fluorescence by different concentrations of gold-silica core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Jiawei; Wang, Kai; Wu, Ke; Qian, Lihua; Long, Hua; Wang, Bing; Lu, Peixiang

    2015-08-01

    Colloidal solutions of Au/SiO2 core-shell nanoparticles (NPs) are synthesized. The diameters of Au core are 40 nm, 60 nm, 80 nm and 110 nm and the thickness of SiO2 shell is 20 nm. The metal-enhanced fluorescence of CdTe quantum dots (QDs) in aqueous solutions is studied by mixing the Au/SiO2 NPs colloidal solutions with different concentrations. As the molar ratio of the Au/SiO2 NPs and the CdTe QDs increases, the fluorescence enhancement factor grows rapidly because of the plasmonic enhancement, and then a reduction of the enhancement factor is observed because of the absorption of Au/SiO2 NPs. The largest fluorescence enhancement factor of 8 is obtained at the optimal molar ratio, when the surface plasmon resonance of the Au/SiO2 NPs (60 nm) matches the emission peak of the CdTe QDs. The results of our theoretical analysis support the experimental results.

  5. 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.

  6. Development of dual-emission ratiometric probe-based on fluorescent silica nanoparticle and CdTe quantum dots for determination of glucose in beverages and human body fluids.

    PubMed

    Zhai, Hong; Feng, Ting; Dong, Lingyu; Wang, Liyun; Wang, Xiangfeng; Liu, Hailing; Liu, Yuan; Chen, Luan; Xie, MengXia

    2016-08-01

    A novel dual emission ratiometric fluorescence probe for determination of glucose has been developed. The reference dye fluorescence isothiocyanate (FITC) has been encapsulated in the silica nanoparticles and then the red emission CdTe QDs were grafted on the surface of the silica particles to obtain the fluorescence probe. With glucose and dopamine as substrates, the glucose level was proportional to the fluorescence ratio change of above probe caused by dopamine oxidation, which was produced via bienzyme catalysis (glucose oxidase and horseradish peroxidase). The established approach was sensitive and selective, and has been applied to determine the glucose in beverage, urine and serum samples. The average recoveries of the glucose at various spiking levels ranged from 95.5% to 108.9% with relative standard deviations from 1.5% to 4.3%. The results provided a clue to develop sensors for rapid determination of the target analytes from complex matrices. PMID:26988523

  7. 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

  8. 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

  9. Fluorescent nanoparticles based on AIE fluorogens for bioimaging

    NASA Astrophysics Data System (ADS)

    Yan, Lulin; Zhang, Yan; Xu, Bin; Tian, Wenjing

    2016-01-01

    Fluorescent nanoparticles (FNPs) have recently attracted increasing attention in the biomedical field because of their unique optical properties, easy fabrication and outstanding performance in imaging. Compared with conventional molecular probes including small organic dyes and fluorescent proteins, FNPs based on aggregation-induced emission (AIE) fluorogens have shown significant advantages in tunable emission and brightness, good biocompatibility, superb photo- and physical stability, potential biodegradability and facile surface functionalization. In this review, we summarize the latest advances in the development of fluorescent nanoparticles based on AIE fluorogens including polymer nanoparticles and silica nanoparticles over the past few years, and the various biomedical applications based on these fluorescent nanoparticles are also elaborated.

  10. Mesoporous silica nanoparticles functionalized with fluorescent and MRI reporters for the visualization of murine tumors overexpressing αvβ3 receptors

    NASA Astrophysics Data System (ADS)

    Hu, He; Arena, Francesca; Gianolio, Eliana; Boffa, Cinzia; di Gregorio, Enza; Stefania, Rachele; Orio, Laura; Baroni, Simona; Aime, Silvio

    2016-03-01

    A novel fluorescein/Gd-DOTAGA containing nanoprobe for the visualization of tumors by optical and Magnetic Resonance Imaging (MRI) is reported herein. It is based on the functionalization of the surface of small mesoporous silica nanoparticles (MSNs) (~30 nm) with the arginine-glycine-aspartic (RGD) moieties, which are known to target αvβ3 integrin receptors overexpressed in several tumor cells. The obtained nanoprobe (Gd-MSNs-RGD) displays good stability, tolerability and high relaxivity (37.6 mM-1 s-1 at 21.5 MHz). After a preliminary evaluation of their cytotoxicity and targeting capability toward U87MG cells by in vitro fluorescence and MR imaging, the nanoprobes were tested in vivo by T1-weighted MR imaging of xenografted murine tumor models. The obtained results demonstrated that the Gd-MSNs-RGD nanoprobes are good reporters both in vitro and in vivo for the MR-visualization of tumor cells overexpressing αvβ3 integrin receptors.A novel fluorescein/Gd-DOTAGA containing nanoprobe for the visualization of tumors by optical and Magnetic Resonance Imaging (MRI) is reported herein. It is based on the functionalization of the surface of small mesoporous silica nanoparticles (MSNs) (~30 nm) with the arginine-glycine-aspartic (RGD) moieties, which are known to target αvβ3 integrin receptors overexpressed in several tumor cells. The obtained nanoprobe (Gd-MSNs-RGD) displays good stability, tolerability and high relaxivity (37.6 mM-1 s-1 at 21.5 MHz). After a preliminary evaluation of their cytotoxicity and targeting capability toward U87MG cells by in vitro fluorescence and MR imaging, the nanoprobes were tested in vivo by T1-weighted MR imaging of xenografted murine tumor models. The obtained results demonstrated that the Gd-MSNs-RGD nanoprobes are good reporters both in vitro and in vivo for the MR-visualization of tumor cells overexpressing αvβ3 integrin receptors. Electronic supplementary information (ESI) available: Absorption and emission spectra, energy

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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

  16. 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

  17. 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

  18. Multifunctional particles: Magnetic nanocrystals and gold nanorods coated with fluorescent dye-doped silica shells

    SciTech Connect

    Heitsch, Andrew T.; Smith, Danielle K.; Patel, Reken N.; Ress, David; Korgel, Brian A.

    2008-07-15

    Multifunctional colloidal core-shell nanoparticles of magnetic nanocrystals (of iron oxide or FePt) or gold nanorods encapsulated in silica shells doped with the fluorescent dye, Tris(2,2'-bipyridyl)dichlororuthenium(II) hexahydrate (Rubpy) were synthesized. The as-prepared magnetic nanocrystals are initially hydrophobic and were coated with silica using a microemulsion approach, while the as-prepared gold nanorods are hydrophilic and were coated with silica using a Stoeber type of process. Each approach yielded monodisperse nanoparticles with uniform fluorescent dye-doped silica shells. These colloidal heterostructures have the potential to be used as dual-purpose tags-exhibiting a fluorescent signal that could be combined with either dark-field optical contrast (in the case of the gold nanorods), or enhanced contrast in magnetic resonance images (in the case of magnetic nanocrystal cores). The optical and magnetic properties of the fluorescent silica-coated gold nanorods and magnetic nanocrystals are reported. - Graphical abstract: Colloidal gold nanorods and iron platinum and iron oxide nanocrystals were encapsulated with fluorescent dye-doped silica shells using a generic coating strategy. These heterostructures are promising contrast agents for dual-mode medical imaging. Their optical and magnetic properties were studied and are reported here.

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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

  5. 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

  6. 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

  7. Mesoporous Silica Nanoparticles and Films for Cargo Delivery

    NASA Astrophysics Data System (ADS)

    Guardado Alvarez, Tania Maria

    -IR photoredox-induced nanoparticle delivery system that may lead to a new type of photodynamic drug release therapy. Chapter 4 focuses on the attachment of a photoacid molecule on the surface of silica nanoparticles. Upon light irradiation the pKa of the photoacid molecules decreases causing the dissociation of the proton and the acidification of the nanoparticle surface. The local nanoparticle surface acidification was probed using a pH sensitive nanovalve that was attached to MSNs next to a photoacid. The particles were loaded with a fluorescent dye that was contained by the naovalve and released upon acidification of the surrounding environment. The amount of the dye release was measure continuously by detecting its fluorescence. Chapter 5 focuses on the synthesis of materials that utilize the micropatterned structure of a mesoporous silica film to successfully load and release cargo using a thermal sensitive polymer. Films with pore sizes of ˜2 and ˜5 nm aligned in the pulling direction were synthesized using evaporation induced self-assembly techniques. The pores are exposed using a new method of stamping micropatterns without the use hydrofluoric acid. A well-studied temperature dependent polymer [poly(N-isopropylacrylamide-co-acrylamide)] was grafted onto the surface of these films to act as a temperature activated gatekeeper. Below the lower critical solution temperature (LCST) the polymer is erect and can block the pore openings, trapping cargo inside the pores. When the temperature is above the LCST the polymer collapses and unblocks the pores, allowing cargo to escape. The loading capacities as well as the reusability of these films were studied.

  8. 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.

  9. 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

  10. A new type of silica-coated Gd2(CO3)3:Tb nanoparticle as a bifunctional agent for magnetic resonance imaging and fluorescent imaging

    NASA Astrophysics Data System (ADS)

    Wu, Yanli; Xu, Xianzhu; Tang, Qun; Li, Yongxiu

    2012-05-01

    We report a new type of dual modal nanoprobe to combine optical and magnetic resonance bioimaging. A simple reverse microemulsion method and coating process was introduced to synthesize silica-coated Gd2(CO3)3:Tb nanoparticles, and the particles, with an average diameter of 16 nm, can be dispersed in water. As in vitro cell imaging of the nanoprobe shows, the nanoprobe accomplishes delivery to gastric SGC7901 cancer cells successfully in a short time, as well as NCI-H460 lung cancer cells. Furthermore, it presents no evidence of cell toxicity or adverse affect on kidney cell growth under high dose, which makes the nanoprobe’s optical bioimaging modality available. The possibility of using the nanoprobe for magnetic resonance imaging is also demonstrated, and the nanoprobe displays a clear T1-weighted effect and could potentially serve as a bimodal T1-positive contrast agent. Therefore, the new nanoprobe formed from carbonate nanoprobe doped with rare earth ions provides the dual modality of optical and magnetic resonance imaging.

  11. 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

  12. 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

  13. 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.

  14. Multifunctional Particles: Magnetic Nanocrystals and Gold Nanorods Coated with Fluorescent Dye-Doped Silica Shells

    PubMed Central

    Heitsch, Andrew T.; Smith, Danielle K.; Patel, Reken E.; Ress, David; Korgel, Brian A.

    2008-01-01

    Multifunctional colloidal core-shell nanoparticles of magnetic nanocrystals (of iron oxide or FePt) or gold nanorods encapsulated in silica shells doped with the fluorescent dye, Tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate (Rubpy) were synthesized. The as-prepared magnetic nanocrystals are initially hydrophobic and were coated with silica using a microemulsion approach, while the as-prepared gold nanorods are hydrophilic and were coated with silica using a Stöber-type of process. Each approach yielded monodisperse nanoparticles with uniform fluorescent dye-doped silica shells. These colloidal heterostructures have the potential to be used as dual-purpose tags—exhibiting a fluorescent signal that could be combined with either dark-field optical contrast (in the case of the gold nanorods), or enhanced contrast in magnetic resonance images (in the case of magnetic nanocrystal cores). The optical and magnetic properties of the fluorescent silica-coated gold nanorods and magnetic nanocrystals are reported. PMID:19578476

  15. 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

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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

  9. 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

  10. 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.

  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. 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

  13. 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.

  14. 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

  15. Synthesis, modification, bioconjugation of silica coated fluorescent quantum dots and their application for mycotoxin detection.

    PubMed

    Goftman, Valentina V; Aubert, Tangi; Ginste, Dries Vande; Van Deun, Rik; Beloglazova, Natalia V; Hens, Zeger; De Saeger, Sarah; Goryacheva, Irina Yu

    2016-05-15

    To create bright and stable fluorescent biolabels for immunoassay detection of mycotoxin deoxynivalenol in food and feed, CdSe/CdS/ZnS core-shell quantum dots (QDs) were encapsulated in silica nanoparticles through a water-in-oil reverse microemulsion process. The optical properties and stability of the obtained silica coated QDs (QD@SiO2), modified with amino, carboxyl and epoxy groups and stabilized with polyethylene glycol fragments, were characterized in order to assess their bioapplicability. The developed co-condensation techniques allowed maintaining 80% of the initial fluorescent properties and yielded stable fluorescent labels that could be easily activated and bioconjugated. Further, the modified QD@SiO2 were efficiently conjugated with antibodies and applied as a novel label in a microtiter plate based immunoassay and a quantitative column-based rapid immunotest for deoxynivalenol detection with IC50 of 473 and 20 ng/ml, respectively. PMID:26745794

  16. 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

  17. Stable and responsive fluorescent carbon nanotube silica gels

    SciTech Connect

    Dattelbaum, Andrew M; Gupta, Gautam; Doorn, Stephen K; Duque, Juan G

    2010-05-03

    Here we report a general route to prepare silica nanocomposite gels doped with fluorescent single walled carbon nanotubes (SWNT). We show that tetramethylorthosilicate (TMOS) vapors can be used to gel an aqueous suspension of surfactant-wrapped SWNT while maintaining fluorescence from the semiconducting nanotubes. The vapor phase silica process is performed at room temperature and is simple, reproducible, relatively quick, and requires no dilution of SWNT dispersions. However, exposure of aqueous SWNT suspensions to TMOS vapors resulted in an acidification of the suspension prior to gelation that caused a decrease in the emission signal from sodium dodecylsulfate (SDS) wrapped SWNT. We also show that although the SWNT are encapsulated in silica the emission signal from the encapsulated SWNT may be attenuated by exposing the nanocomposites to small aromatic molecules known to mitigate SWNT emission. These results demonstrate a new route for the preparation of highly luminescent SWNT/silica composite materials that are potentially useful for future sensing applications.

  18. Dual-emissive fluorescence measurements of hydroxyl radicals using a coumarin-activated silica nanohybrid probe.

    PubMed

    Liu, Saisai; Zhao, Jun; Zhang, Kui; Yang, Lei; Sun, Mingtai; Yu, Huan; Yan, Yehan; Zhang, Yajun; Wu, Lijun; Wang, Suhua

    2016-04-01

    This work reports a novel dual-emissive fluorescent probe based on dye hybrid silica nanoparticles for ratiometric measurement of the hydroxyl radical (˙OH). In the probe sensing system, the blue emission of coumarin dye (coumarin-3-carboxylic acid, CCA) immobilized on the nanoparticle surface is selectively enhanced by ˙OH due to the formation of a coumarin hydroxylation product with strong fluorescence, whereas the emission of red fluorescent dye encapsulated in the silica nanoparticle is insensitive to ˙OH as a self-referencing signal, and so the probe provides a good quantitative analysis based on ratiometric fluorescence measurement with a detection limit of 1.65 μM. Moreover, the probe also shows high selectivity for ˙OH determination against metal ions, other reactive oxygen species and biological species. More importantly, it exhibits low cytotoxicity and high biocompatibility in living cells, and has been successfully used for cellular imaging of ˙OH, showing its promising application for monitoring of intracellular ˙OH signaling events. PMID:26958658

  19. 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.

  20. 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.

  1. Nanoparticle metrology in sol-gels using multiphoton excited fluorescence

    NASA Astrophysics Data System (ADS)

    Karolin, J.; Geddes, C. D.; Wynne, K.; Birch, D. J. S.

    2002-01-01

    We have developed a method of measuring the growth of nanoparticles during sol-gel glass formation based on labelling the particle with a fluorescent dye and determining the multiphoton excited decay of fluorescence anisotropy due to Brownian rotation. Multiphoton excitation is shown to give a higher dynamic range of measurement than one-photon excitation. We illustrate the sub-nanometre resolution and stability of our approach by detecting a 0.8-1.1 nm silica particle hydrodynamic mean radius increase in a tetramethylorthosilicate sol at pH 2.3 labelled with rhodamine 6G and observed over ≈4 weeks and also with a stable silica colloid of radius 6 nm, pH 8.9, labelled with a 6-methoxyquinoline-type dye.

  2. Fluorescence enhancement of light-harvesting complex 2 from purple bacteria coupled to spherical gold nanoparticles

    SciTech Connect

    Bujak, Ł.; Czechowski, N.; Piatkowski, D.; Litvin, R.; Mackowski, S.; Brotosudarmo, T. H. P.; Pichler, S.; Cogdell, R. J.; Heiss, W.

    2011-10-24

    The influence of plasmon excitations in spherical gold nanoparticles on the optical properties of a light-harvesting complex 2 (LH2) from the purple bacteria Rhodopseudomonas palustris has been studied. Systematic analysis is facilitated by controlling the thickness of a silica layer between Au nanoparticles and LH2 complexes. Fluorescence of LH2 complexes features substantial increase when these complexes are separated by 12 nm from the gold nanoparticles. At shorter distances, non-radiative quenching leads to a decrease of fluorescence emission. The enhancement of fluorescence originates predominantly from an increase of absorption of pigments comprising the LH2 complex.

  3. Fluorescence enhancement of light-harvesting complex 2 from purple bacteria coupled to spherical gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Bujak, Ł.; Czechowski, N.; Piatkowski, D.; Litvin, R.; Mackowski, S.; Brotosudarmo, T. H. P.; Cogdell, R. J.; Pichler, S.; Heiss, W.

    2011-10-01

    The influence of plasmon excitations in spherical gold nanoparticles on the optical properties of a light-harvesting complex 2 (LH2) from the purple bacteria Rhodopseudomonas palustris has been studied. Systematic analysis is facilitated by controlling the thickness of a silica layer between Au nanoparticles and LH2 complexes. Fluorescence of LH2 complexes features substantial increase when these complexes are separated by 12 nm from the gold nanoparticles. At shorter distances, non-radiative quenching leads to a decrease of fluorescence emission. The enhancement of fluorescence originates predominantly from an increase of absorption of pigments comprising the LH2 complex.

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. Concentration Dependence of Gold Nanoparticles for Fluorescence Enhancement

    NASA Astrophysics Data System (ADS)

    Solomon, Joel; Wittmershaus, Bruce

    Noble metal nanoparticles possess a unique property known as surface plasmon resonance in which the conduction electrons oscillate due to incoming light, dramatically increasing their absorption and scattering of light. The oscillating electrons create a varying electric field that can affect nearby molecules. The fluorescence and photostability of fluorophores can be enhanced significantly when they are near plasmonic nanoparticles. This effect is called metal enhanced fluorescence (MEF). MEF from two fluorescence organic dyes, Lucifer Yellow CH and Riboflavin, was measured with different concentrations of 50-nm colloidal gold nanoparticles (Au-NP). The concentration range of Au-NP was varied from 2.5 to 250 pM. To maximize the interaction, the dyes were chosen so their emission spectra had considerable overlap with the absorption spectra of the Au-NP, which is common in MEF studies. If the dye molecules are too close to the surface of Au-NP, fluorescence quenching can occur instead of MEF. To try to observe this difference, silica-coated Au-NP were compared to citrate-based Au-NP; however, fluorescence quenching was observed with both Au-NP. This material is based upon work supported by the National Science Foundation under Grant Number NSF-ECCS-1306157.

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. Carbon Nanoparticle-based Fluorescent Bioimaging Probes

    PubMed Central

    Bhunia, Susanta Kumar; Saha, Arindam; Maity, Amit Ranjan; Ray, Sekhar C.; Jana, Nikhil R.

    2013-01-01

    Fluorescent nanoparticle-based imaging probes have advanced current labelling technology and are expected to generate new medical diagnostic tools based on their superior brightness and photostability compared with conventional molecular probes. Although significant progress has been made in fluorescent semiconductor nanocrystal-based biological labelling and imaging, the presence of heavy metals and the toxicity issues associated with heavy metals have severely limited the application potential of these nanocrystals. Here, we report a fluorescent carbon nanoparticle-based, alternative, nontoxic imaging probe that is suitable for biological staining and diagnostics. We have developed a chemical method to synthesise highly fluorescent carbon nanoparticles 1–10 nm in size; these particles exhibit size-dependent, tunable visible emission. These carbon nanoparticles have been transformed into various functionalised nanoprobes with hydrodynamic diameters of 5–15 nm and have been used as cell imaging probes. PMID:23502324

  15. 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.

  16. Fluorescence properties of dye doped mesoporous silica

    NASA Astrophysics Data System (ADS)

    Carbonaro, Carlo M.; Corpino, Riccardo; Ricci, Pier Carlo; Chiriu, Daniele; Cannas, Carla

    2014-10-01

    In this paper we present a review of the main results we obtained studying the emission properties of organic-inorganic hybrids obtained combining mesoporous silica and Xantene dyes, in particular the standard referenc Rhodamine 6G. The purpose of the review is to show the possibility to efficiently "dope" the transparent inorganic porous matrix to obtain promising systems for photonic and biomedical applications. The strategies to solve the concentration effect and the leaching phenomenon are discussed within the framework of the single exciton theory.

  17. Fluorescence properties of dye doped mesoporous silica

    SciTech Connect

    Carbonaro, Carlo M. Corpino, Riccardo Ricci, Pier Carlo Chiriu, Daniele; Cannas, Carla

    2014-10-21

    In this paper we present a review of the main results we obtained studying the emission properties of organic-inorganic hybrids obtained combining mesoporous silica and Xantene dyes, in particular the standard reference Rhodamine 6G. The purpose of the review is to show the possibility to efficiently 'dope' the transparent inorganic porous matrix to obtain promising systems for photonic and biomedical applications. The strategies to solve the concentration effect and the leaching phenomenon are discussed within the framework of the single exciton theory.

  18. 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

  19. 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.

  20. Glutaraldehyde-chitosan and poly (vinyl alcohol) blends, and fluorescence of their nano-silica composite films.

    PubMed

    Hu, Huawen; Xin, John H; Hu, Hong; Chan, Allan; He, Liang

    2013-01-01

    In this study, a commercial chitosan cross-linked with glutaraldehyde (GA-chitosan) having the autofluorescent property was effectively blended with a poly (vinyl alcohol) (PVA) matrix, in the formation of a transparent and fluorescent blend film. The fluorescent efficiency of the film was enhanced with red-shifted emission band by increasing the concentrations of the GA-chitosan and decreasing the PVA crystallinity. It was found that the incorporation of silica nanoparticles could further decrease the PVA crystallinity, enhance the fluorescent efficiency, and largely redshift the emission band, as compared with the neat GA-chitosan-PVA blend film. This fluorescent property could be finely tuned by careful doping of the silica nanoparticles and change of the PVA crystallinity. These phenomena could be reasonably explained by high extent of isolation of the fluorophores, increase of the stiffness of the fluorescent conjugated planar structure, and further decrease of the PVA crystallinity. In addition, the introduction of the nano-silica could improve the water and heat resistances of the GA-chitosan-PVA based silica nanocomposites. PMID:23044137

  1. Optical tracking of organically modified silica nanoparticles as DNA carriers: A nonviral, nanomedicine approach for gene delivery

    NASA Astrophysics Data System (ADS)

    Roy, Indrajit; Ohulchanskyy, Tymish Y.; Bharali, Dhruba J.; Pudavar, Haridas E.; Mistretta, Ruth A.; Kaur, Navjot; Prasad, Paras N.

    2005-01-01

    This article reports a multidisciplinary approach to produce fluorescently labeled organically modified silica nanoparticles as a nonviral vector for gene delivery and biophotonics methods to optically monitor intracellular trafficking and gene transfection. Highly monodispersed, stable aqueous suspensions of organically modified silica nanoparticles, encapsulating fluorescent dyes and surface functionalized by cationic-amino groups, are produced by micellar nanochemistry. Gel-electrophoresis studies reveal that the particles efficiently complex with DNA and protect it from enzymatic digestion of DNase 1. The electrostatic binding of DNA onto the surface of the nanoparticles, due to positively charged amino groups, is also shown by intercalating an appropriate dye into the DNA and observing the Förster (fluorescence) resonance energy transfer between the dye (energy donor) intercalated in DNA on the surface of nanoparticles and a second dye (energy acceptor) inside the nanoparticles. Imaging by fluorescence confocal microscopy shows that cells efficiently take up the nanoparticles in vitro in the cytoplasm, and the nanoparticles deliver DNA to the nucleus. The use of plasmid encoding enhanced GFP allowed us to demonstrate the process of gene transfection in cultured cells. Our work shows that the nanomedicine approach, with nanoparticles acting as a drug-delivery platform combining multiple optical and other types of probes, provides a promising direction for targeted therapy with enhanced efficacy as well as for real-time monitoring of drug action. nonviral vector | ORMOSIL nanoparticles | confocal microscopy

  2. 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

  3. 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.

  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. 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

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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

  18. 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

  19. Photosensitive Fluorescent Dye Contributes to Phototoxicity and Inflammatory Responses of Dye-doped Silica NPs in Cells and Mice

    PubMed Central

    Zhao, Yang; Ye, Yan; Zhou, Xikun; Chen, Jiao; Jin, Yuihui; Hanson, Aaron; Zhao, Julia Xiaojun; Wu, Min

    2014-01-01

    Dye-doped fluorescent silica nanoparticles provide highly intense and photostable fluorescence signals. However, some dopant dye molecules are photosensitive. A widely-used photosensitive fluorescent dopant, RuBpy, was chosen to systematically investigate the phototoxicity of the dye-doped silica nanoparticles (NPs). We investigated cell viability, DNA damage, and Reactive Oxygen Species (ROS) levels in alveolar macrophages using the dye-doped NPs with or without irradiation. Our results showed that the RuBpy-doped silica NPs could induce significant amount of ROS, DNA damage, apoptosis and impaired proliferation in MH-S cells. In vivo studies in mice showed that RuBpy-doped silica NPs induced significant inflammatory cytokine production and lowered expression in signaling proteins such as ERK1/2 and NF-κB as well as increased lung injury determined by myeloperoxidase and lipid peroxidation. Strikingly, we also found that both RuBpy alone and NPs induced systemic signaling activation in the kidney compared to the liver and lung where showed highly selective signaling patterns, which is more pronounced than RuBpy-doped silica NPs. Moreover, we discovered a critical biomarker (e.g., HMGB1) for silica NPs-induced stress and toxicity and demonstrated differentially-regulated response patterns in various organs. Our results indicate for the first time that the RuBpy-doped silica NPs may impose less inflammatory responses but stronger thermotherapeutic effects on target cells in animals than naked NPs in a time- and dose-dependent manner. PMID:24578727

  20. A convenient sandwich assay of thrombin in biological media using nanoparticle-enhanced fluorescence polarization.

    PubMed

    Yue, Qiaoli; Shen, Tongfei; Wang, Lei; Xu, Shuling; Li, Haibo; Xue, Qingwang; Zhang, Yuanfu; Gu, Xiaohong; Zhang, Shuqiu; Liu, Jifeng

    2014-06-15

    A new aptamer biosensor was presented for the detection of thrombin in this work, which was based on fluorescence polarization (FP) using silica nanoparticles as enhancement probe. The silica nanoparticles covered by streptavidin were tagged with a thrombin aptamer (5'-biotin-GGTTGGTGTGGTTGG-3'), which was bound to the surface of silica nanoparticle through the specific interaction between streptavidin and biotin. In the presence of thrombin, it induced the aptamer to form quadruplex structure. When the other thrombin aptamer labeled with fluorescein (5'-FAM-AGTCCGTGGTAGGGCAGGTTGGGGTGACT-3') was added to the above system, a sandwich structure can form at the surface of silica nanoparticles. The fluorescence polarization was therefore enhanced and quantification between fluorescence polarization signal and concentration of thrombin was built. The sensor provided a linear range from 0.6 to 100 nM for thrombin with a detection limit of 0.20 nM (3.29 SB/m, according to the recent recommendation of IUPAC) in a homogeneous media. The same linear range was obtained in spiked human serum samples with a slightly higher detection limit (0.26 nM), demonstrating high anti-interference of the sensor in a complex biological sample matrix. And the sensor can be used to monitor spiked concentration of thrombin level in real human plasma with satisfactory results obtained. PMID:24508546

  1. 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.

  2. Fluorescent Functionalized Mesoporous Silica for Radioactive Material Extraction

    SciTech Connect

    Li, Juan; Zhu, Kake; Shang, Jianying; Wang, Donghai; Nie, Zimin; Guo, Ruisong; Liu, Chongxuan; Wang, Zheming; Li, Xiaolin; Liu, Jun

    2012-08-01

    Mesoporous silica with covalently bound salicylic acid molecules incorporated in the structure was synthesized with a one-pot, co-condensation reaction at room temperature. The as-synthesized material has a large surface area, uniform particle size, and an ordered pore structure as determined by characterization with transmission electron microscopy, thermal gravimetric analysis, and infrared spectra, etc. Using the strong fluorescence and metal coordination capability of salicylic acid, functionalized mesoporous silica (FMS) was developed to track and extract radionuclide contaminants, such as uranyl [U(VI)] ions encountered in subsurface environments. Adsorption measurements showed a strong affinity of the FMS toward U(VI) with a Kd value of 105 mL/g, which is four orders of magnitude higher than the adsorption of U(VI) onto most of the sediments in natural environments. The new materials have a potential for synergistic environmental monitoring and remediation of the radionuclide U(VI) from contaminated subsurface environments.

  3. 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.

  4. 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

  5. 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.

  6. Silica micro/nanospheres for theranostics: from bimodal MRI and fluorescent imaging probes to cancer therapy

    PubMed Central

    Walia, Shanka

    2015-01-01

    Summary Nano-theranostics offer remarkable potential for future biomedical technology with simultaneous applications for diagnosis and therapy of disease sites. Through smart and careful chemical modifications of the nanoparticle surface, these can be converted to multifunctional tiny objects which in turn can be used as vehicle for delivering multimodal imaging agents and therapeutic material to specific target sites in vivo. In this sense, bimodal imaging probes that simultaneously enable magnetic resonance imaging and fluorescence imaging have gained tremendous attention because disease sites can be characterized quick and precisely through synergistic multimodal imaging. But such hybrid nanocomposite materials have limitations such as low chemical stability (magnetic component) and harsh cytotoxic effects (fluorescent component) and, hence, require a biocompatible protecting agent. Silica micro/nanospheres have shown promise as protecting agent due to the high stability and low toxicity. This review will cover a full description of MRI-active and fluorescent multifunctional silica micro/nanospheres including the design of the probe, different characterization methods and their application in imaging and treatment in cancer. PMID:25821696

  7. Fluorescence studies of beer protein uptake by silica

    NASA Astrophysics Data System (ADS)

    Apperson, Kathleen; Birch, David J. S.; Leiper, Kenneth; McKeown, Ian P.

    2001-05-01

    Fluorescence has been investigated with respect to new methods for monitoring protein uptake by silica, with particular attention being given to haze forming proteins and foam proteins present in beer. These are of particular interest to the brewing industry as an important aspect of the brewing process is the prevention of chill haze formation. This is necessary in order to maintain the clarity of the beer and to extend the shelf life. Chill haze, which is a result of the interaction of certain proteins with some polyphenols, can be prevented by the removal of one or both of these constituents.

  8. 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

  9. 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).

  10. 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

  11. 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.

  12. 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

  13. Labelling of silica microspheres with fluorescent lanthanide-doped LaF3 nanocrystals

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Lu, Meihua

    2007-07-01

    Fluorescent microspheres have been demonstrated to be useful in a variety of biological applications. Fluorescent silica or polymer microspheres have been produced by incorporation of chromophores into the microspheres, which usually produces microspheres with nonuniform sizes and reduced fluorescence. Here we present a simple and straightforward method to produce silica microspheres with fluorescent lanthanide-doped LaF3 nanocrystals grown on the surface. LaF3 nanocrystals are in situ grown on silica microspheres of different sizes to form a raspberry-like structure. The microspheres exhibit strong fluorescence and the colour could be altered by changing the lanthanide ions doped in LaF3 nanocrystals.

  14. 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

  15. 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

  16. Photoswitchable fluorescent nanoparticles and their emerging applications

    NASA Astrophysics Data System (ADS)

    Zhang, Yuanlin; Zhang, Kaiquan; Wang, Jie; Tian, Zhiyuan; Li, Alexander D. Q.

    2015-11-01

    Although fluorescence offers ultrasensitivity, real-world applications of fluorescence techniques encounter many practical problems. As a noninvasive means to investigate biomolecular mechanisms, pathways, and regulations in living cells, the intrinsic heterogeneity and inherent complexity of biological samples always generates optical interferences such as autofluorescence. Therefore, innovative fluorescence technologies are needed to enhance measurement reliability while not compromising sensitivity. In this review, we present current strategies that use photoswitchable nanoparticles to address these real-world challenges. The unique feature in these photoswitchable nanoparticles is that fundamental molecular photoswitches are playing the critical role of fluorescence modulation rather than traditional methods like modulating the light source. As a result, new innovative technologies that have recently emerged include super-resolution imaging, frequency-domain imaging, antiphase dual-color correlation, etc. Some of these methods improve imaging resolution down to the nanometer level, while others boost the detection sensitivity by orders of magnitude and confirm the nanoparticle probes unambiguously. These enhancements, which are not possible with non-photoswitching molecular probes, are the central topics of this review.

  17. 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.

  18. 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).

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. Fluorescent nanoparticle probes for imaging of cancer.

    PubMed

    Santra, Swadeshmukul; Malhotra, Astha

    2011-01-01

    Fluorescent nanoparticles (FNPs) have received immense popularity in cancer imaging in recent years because of their attractive optical properties. In comparison to traditional organic-based fluorescent dyes and fluorescent proteins, FNPs offer much improved sensitivity and photostability. FNPs in certain size range have a strong tendency to enter and retain in solid tumor tissue with abnormal (leaky) vasculature--a phenomenon known as Enhanced Permeation and Retention (EPR) effect, advancing their use for in vivo tumor imaging. Furthermore, large surface area of FNPs and their usual core-shell structure offer a platform for designing and fabricating multimodal/multifunctional nanoparticles (MMNPs). For effective cancer imaging, often the optical imaging modality is integrated with other nonoptical-based imaging modalities such as MRI, X-ray, and PET, thus creating multimodal nanoparticle (NP)-based imaging probes. Such multimodal NP probes can be further integrated with therapeutic drug as well as cancer targeting agent leading to multifunctional NPs. Biocompatibility of FNPs is an important criterion that must be seriously considered during FNP design. NP composition, size, and surface chemistry must be carefully selected to minimize potential toxicological consequences both in vitro and in vivo. In this article, we will mainly focus on three different types of FNPs: dye-loaded NPs, quantum dots (Qdots), and phosphores; briefly highlighting their potential use in translational research. PMID:21480546

  12. 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

  13. 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.

  14. 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

  15. 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

  16. 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

  17. 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.

  18. Loading of atorvastatin and linezolid in β-cyclodextrin-conjugated cadmium selenide/silica nanoparticles: A spectroscopic study.

    PubMed

    Antony, Eva Janet; Shibu, Abhishek; Ramasamy, Sivaraj; Paulraj, Mosae Selvakumar; Enoch, Israel V M V

    2016-08-01

    The preparation of β-cyclodextrin-conjugated cadmium selenide-silica nanoparticles, the loading of two drugs viz., Atorvastatin and linezolid in the cyclodextrin cavity, and the fluorescence energy transfer between CdSe/SiO2 nanoparticles and the drugs encapsulated in the cyclodextrin cavity are reported in this paper. IR spectroscopy, X-ray diffractometry, transmission electron microscopy, and particle size analysis by light-scattering experiment were used as the tools of characterizing the size and the crystal system of the nanoparticles. The nanoparticles fall under hexagonal system. The silica-shell containing CdSe nanoparticles were functionalized by reaction with aminoethylamino-β-cyclodextrin. Fluorescence spectra of the nanoparticles in their free and drug-encapsulated forms were studied. The FÖrster distances between the encapsulated drugs and the CdSe nanoparticles are below 3nm. The change in the FÖrster resonance energy parameters under physiological conditions may aid in tracking the release of drugs from the cavity of the cyclodextrin. PMID:27157743

  19. 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

  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. Benefits of Silica Core-Shell Structures on the Temperature Sensing Properties of Er,Yb:GdVO4 Up-Conversion Nanoparticles.

    PubMed

    Savchuk, Oleksandr A; Carvajal, Joan J; Cascales, C; Aguiló, M; Díaz, F

    2016-03-23

    We studied the temperature-dependent luminescence of GdVO4 nanoparticles co-doped with Er(3+) (1 mol %) and Yb(3+) (20 mol %) and determined their thermal sensing properties through the fluorescence intensity ratio (FIR) technique. We also analyzed how a silica coating, in a core-shell structure, affects the temperature sensing properties of this material. Spectra were recorded in the range of biological temperatures (298-343 K). The absolute sensitivity for temperature determination calculated for the core-shell nanoparticles is double the one calculated for bare nanoparticles, achieving a thermal resolution of 0.4 K. Moreover, silica-coated nanoparticles show good dispersibility in different solvents, such as water, DMSO, and methanol. Also, they show good luminescence stability without interactions with solvent molecules. Furthermore, we also observed that the silica coating shell prevents progressive heating of the nanoparticles during prolonged excitation periods with the 980 nm laser, preventing effects on their thermometric applications. PMID:26949971

  2. Development of fluorescent nanoparticle-labeled lateral flow assay for the detection of nucleic acids.

    PubMed

    Wang, Yuhong; Nugen, Sam R

    2013-10-01

    The rapid, specific and sensitive detection of nucleic acids is of utmost importance for the identification of infectious agents, diagnosis and treatment of genetic diseases, and the detection of pathogens related to human health and safety. Here we report the development of a simple and sensitive nucleic acid sequence-based and Ru(bpy)3 (2+)-doped silica nanoparticle-labeled lateral flow assay which achieves low limit of detection by using fluorescencent nanoparticles. The detection of the synthetic nucleic acid sequences representative of Trypanosoma mRNA, the causative agent for African sleeping sickness, was utilized to demonstrate this assay. The 30 nm spherical Ru(bpy)3 (2+)-doped silica nanoparticles were prepared in aqueous medium by a novel method recently reported. The nanoparticles were modified by 3-glycidoxypropyl trimethoxysilane in order to conjugate to amine-capped oligonucleotide reporter probes. The fluorescent intensities of the fluorescent assays were quantified on a mictrotiter plate reader using a custom holder. The experimental results showed that the lateral flow fluorescent assay developed was more sensitive compared with the traditional colloidal gold test strips. The limit of detection for the fluorescent lateral flow assay developed is approximately 0.066 fmols as compared to approximately 15 fmols for the colloidal gold. The limit of detection can further be reduced about one order of magnitude when "dipstick" format was used. PMID:23525961

  3. 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

  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. 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.

  6. Spectral variation of fluorescence lifetime near single metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Jia; Krasavin, Alexey V.; Webster, Linden; Segovia, Paulina; Zayats, Anatoly V.; Richards, David

    2016-02-01

    We explore the spectral dependence of fluorescence enhancement and the associated lifetime modification of fluorescent molecules coupled to single metal nanoparticles. Fluorescence lifetime imaging microscopy and single-particle dark-field spectroscopy are combined to correlate the dependence of fluorescence lifetime reduction on the spectral overlap between the fluorescence emission and the localised surface plasmon (LSP) spectra of individual gold nanoparticles. A maximum lifetime reduction is observed when the fluorescence and LSP resonances coincide, with good agreement provided by numerical simulations. The explicit comparison between experiment and simulation, that we obtain, offers an insight into the spectral engineering of LSP mediated fluorescence and may lead to optimized application in sensing and biomedicine.

  7. Nanoprecipitation of Fluorescent Conjugated Polymer onto the Surface of Plasmonic Nanoparticle for Fluorescence/Dark-Field Dual-Modality Single Particle Imaging.

    PubMed

    Luo, Wenjuan; Wu, Ming; Li, Shuang; Xu, Yueling; Ye, Zhongju; Wei, Lin; Chen, Bo; Xu, Qing-Hua; Xiao, Lehui

    2016-07-01

    In this work, a hybridized nanoparticle with fluorescence/dark-field dual-modality imaging capability was prepared by nanoprecipitation of fluorescent conjugated polymer onto the surface of silica-coated rod-shape plasmonic nanoparticle. According to the spectroscopic and microscopic characterizations, the fluorescence intensity of conjugated polymer poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(1,4-benzo(2,1',3)-thiadiazole)] (PFBT) could be enhanced around 2-fold after assembling onto the silica-decorated metal nanorod surface compared with the fluorescence intensity of regular PFBT polymer dots without the metal core. The in situ nanorod etching experiment further confirmed this result at the single particle level. In addition to the fluorescence enhancement effect, improved fluorescence stability was obtained from the single particle fluorescence intensity characterizations. As a consequence, this self-assembled functional nanoparticle could be extensively applied to biological imaging such as cellular labeling and single particle tracking owing to the novel and unique optical features, for example, the superior optical stability and specific identification capability from the scattering and fluorescence domain, respectively. Furthermore, the amendable peripheral polymer surface of this nanostructure will promote its applications in biological sensing and imaging-guided functional molecule delivery in the future. PMID:27292151

  8. Upconverting fluorescent nanoparticles for biodetection and photoactivation

    NASA Astrophysics Data System (ADS)

    Huang, Kai; Li, WenKai; Jayakumar, Muthu Kumara Gnanasammandhan; Zhang, Yong

    2013-03-01

    Fluorophores including fluorescent dyes/proteins and quantum dots (QDs) are used for fluorescence-based imaging and detection. These are based on `downconversion fluorescence' and have several drawbacks: photobleaching, autofluorescence, short tissue penetration depth and tissue photo-damage. Upconversion fluorescent nanoparticles (UCNs) emit detectable photons of higher energy in the short wavelength range upon irradiation with near-infrared (NIR) light based on a process termed `upconversion'. UCNs show absolute photostability, negligible autofluorescence, high penetration depth and minimum photodamage to biological tissues. Lanthanide doped nanocrystals with nearinfrared NIR-to-NIR and/or NIR-to-VIS and/or NIR-to-UV upconversion fluorescence emission have been synthesized. The nanocrystals with small size and tunable multi-color emission have been developed. The emission can be tuned by doping different upconverting lanthanide ions into the nanocrystals. The nanocrystals with core-shell structure have also been prepared to tune the emission color. The surfaces of these nanocrystals have been modified to render them water dispersible and biocompatible. They can be used for ultrasensitive interference-free biodetection because most biomolecules do not have upconversion properties. UCNs are also useful for light based therapy with enhanced efficiency, for example, photoactivation.

  9. Synthesis of fluorophore encapsulated silica nanoparticles for the evaluation of the biological fate and toxicity of food relevant nanoparticles

    NASA Astrophysics Data System (ADS)

    Zane, Andrew Paul

    fluorophores, rhodamine 6G and rhodamine 800, into silica shells for direct monitoring in intestinal epithelial cells and tissues of exposed mice. We show that, for small nanoparticles, a typical Stober-type ammonia driven synthesis does not yield stable fluorescence. This has been observed in literature and is attributed to incompletely hydrolyzed silica precursor causing partial dissolution of the silica shell. We remedy this by applying an arginine driven silica shell synthesis, which is known to produce a denser and more stable product at smaller particle sizes. We show that all three fluorophores can be coated in a simple generalized procedure, and the resulting particles all show stable fluorescence with no evidence of dye leakage. Using these particles, we demonstrate that silica nanoparticles can be observed internalizing into C2BBe1 intestinal epithelial cells, and in the tissues of mice that were fed the particles by gavage. We find direct evidence that the particles are absorbed into circulation and subsequently localize in organs throughout the body. Future efforts will attempt to better quantify this accumulation, as well as generalize the procedure to other food relevant nanoparticles such as TiO2.

  10. Fluorescence enhancement of Rhodamine B by monodispersed silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Suslov, A.; Lama, P. T.; Dorsinville, R.

    2015-06-01

    A strong enhancement in fluorescence of Rhodamine B dye in the vicinity of silver monodisperse nanoparticles is presented. The fluorescence of the dye increased as much as by 23 times in the presence of monodispersed silver nanoparticles. The fluorescence enhancement due to monodispersed silver nanoparticles was about 2-3 times larger than in the presence of polydispersed silver nanoparticles. The additional enhancement is explained in terms of emergence of uniform and large local electromagnetic field induced by surface plasmon resonance around an ensemble of monodispersed silver nanoparticles.

  11. A target-induced fluorescent nanoparticle for in situ monitoring of Zn(II).

    PubMed

    John, Carrie L; Huan, Yanfu; Wu, Xu; Jin, Yuhui; Pierce, David T; Zhao, Julia Xiaojun

    2013-09-01

    A target-induced fluorescent silica nanoparticle has been developed for the identification, enrichment and in situ determination of trace amounts of zinc(II). The nanoparticle combines the advantages of target-induced fluorescent compounds and the small size of the nanomaterial to produce a new, smarter nanosignaling material that is capable of selectively enriching a target and detecting a specific binding process in one step. As the target analyte, Zn(II), changes the fluorescence characteristics of the nanoparticle and effectively 'turns on' the fluorescence signal, no separation step is needed to confirm or quantify the binding process. The designed nanoparticle was characterized by several aspects prior to monitoring of Zn(II) in situ. The interferences from common metal ions were studied in detail. The photostability and reversibility of the sensing materials were investigated as well. The ability of this nanoparticle to detect the target Zn(II) provides a great advantage for in situ monitoring targets in biological samples under the fluorescence microscope. PMID:23799230

  12. 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.

  13. Fluorescent colloidal silica rods - synthesis and phase behavior

    NASA Astrophysics Data System (ADS)

    Kuijk, A.

    2012-01-01

    Although the experimental study of spherical colloids has been extensive, similar studies on rod-like particles are rare because suitable model systems are scarce. To fulfill this need, we present the synthesis of monodisperse rod-like silica colloids with tunable dimensions. Rods were produced with diameters of 200 nm and larger and lengths up to 10 µm, which resulted in aspect ratios ranging from 1 to 25. The growth mechanism of these rods involves emulsion droplets of water in pentanol, inside which silica condensation takes place. Since the silica nucleus is attached to the water/pentanol interface, the supply of reactants to the nucleus is anisotropic, causing it to grow on one side only, which results in rod formation. The rods were made suitable for quantitative real-space studies by confocal laser scanning microscopy. Several methods of fluorescent labeling are presented that resulted in constant fluorescence levels, gradients from one rod-end to the other, and even patterns of two colors. Single particle imaging was achieved by creating core-shell rods that had a fluorescent core and a non-fluorescent shell. Alternatively, the rods could be dispersed in a solvent with a low dielectric constant to induce micron-sized double layers. To enable quantitative measurements, a tracking algorithm was developed that identifies the rods' positions and orientations. The newly developed model system was used to study the phase behavior of rods. By combining real-space confocal laser scanning microscopy and small angle X-ray scattering methods, a phase diagram depending on concentration and aspect ratio was constructed, which shows good qualitative agreement with simulation results in literature. This phase diagram includes nematic and smectic phases for the higher aspect ratios. Also, the effect of external fields (electric fields, shear and templates) on the phase behavior was studied. In an electric field, rods aligned themselves with the applied field due to an

  14. 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.

  15. Quenching of chlorophyll fluorescence induced by silver nanoparticles.

    PubMed

    Queiroz, A M; Mezacasa, A V; Graciano, D E; Falco, W F; M'Peko, J-C; Guimarães, F E G; Lawson, T; Colbeck, I; Oliveira, S L; Caires, A R L

    2016-11-01

    The interaction between chlorophyll (Chl) and silver nanoparticles (AgNPs) was evaluated by analyzing the optical behavior of Chl molecules surrounded by different concentrations of AgNPs (10, 60, and 100nm of diameter). UV-Vis absorption, steady state and time-resolved fluorescence measurements were performed for Chl in the presence and absence of these nanoparticles. AgNPs strongly suppressed the Chl fluorescence intensity at 678nm. The Stern-Volmer constant (KSV) showed that fluorescence suppression is driven by the dynamic quenching process. In particular, KSV was nanoparticle size-dependent with an exponential decrease as a function of the nanoparticle diameter. Finally, changes in the Chl fluorescence lifetime in the presence of nanoparticles demonstrated that the fluorescence quenching may be induced by the excited electron transfer from the Chl molecules to the metal nanoparticles. PMID:27280858

  16. Dual aptamer-functionalized silica nanoparticles for the highly sensitive detection of breast cancer.

    PubMed

    Jo, Hunho; Her, Jin; Ban, Changill

    2015-09-15

    In this study, we synthesized dual aptamer-modified silica nanoparticles that simultaneously target two types of breast cancer cells: the mucin 1 (MUC1)(+) and human epidermal growth factor receptor 2 (HER2)(+) cell lines. Dual aptamer system enables a broad diagnosis for breast cancer in comparison with the single aptamer system. The dye-doped silica nanoparticles offer great stability with respect to photobleaching and enable the accurate quantification of breast cancer cells. The morphological and spectroscopic characteristics of the designed Dual-SiNPs were demonstrated via diverse methods such as DLS, zeta potential measurements, UV-vis spectroscopy, and fluorescence spectroscopy. Negatively charged Dual-SiNPs with a homogeneous size distribution showed robust and strong fluorescence. In addition, Dual-SiNPs did not affect cell viability, implying that this probe might be readily available for use in an in vivo system. Through ratio optimization of the MUC1 and HER2 aptamers, the binding capacities of the Dual-SiNPs to both cell lines were maximized. Based on Dual-SiNPs, a highly sensitive quantification of breast cancer cells was performed, resulting in a detection limit of 1 cell/100 μL, which is significantly lower compared with those reported in other studies. Moreover, the developed detection platform displayed high selectivity for only the MUC1(+) and HER2(+) cell lines. It is expected that this valuable diagnostic probe will be a noteworthy platform for the diagnosis and prognosis of breast cancer. PMID:25897882

  17. Multicolor core/shell silica nanoparticles for in vivo and ex vivo imaging

    NASA Astrophysics Data System (ADS)

    Rampazzo, Enrico; Boschi, Federico; Bonacchi, Sara; Juris, Riccardo; Montalti, Marco; Zaccheroni, Nelsi; Prodi, Luca; Calderan, Laura; Rossi, Barbara; Becchi, Serena; Sbarbati, Andrea

    2012-01-01

    Biocompatible highly bright silica nanoparticles were designed, prepared and tested in small living organisms for both in vivo and ex vivo imaging. The results that we report here demonstrate that they are suitable for optical imaging applications as a possible alternative to commercially available fluorescent materials including quantum dots. Moreover, the tunability of their photophysical properties, which was enhanced by the use of different dyes as doping agents, constitutes a very important added value in the field of medical diagnostics.Biocompatible highly bright silica nanoparticles were designed, prepared and tested in small living organisms for both in vivo and ex vivo imaging. The results that we report here demonstrate that they are suitable for optical imaging applications as a possible alternative to commercially available fluorescent materials including quantum dots. Moreover, the tunability of their photophysical properties, which was enhanced by the use of different dyes as doping agents, constitutes a very important added value in the field of medical diagnostics. Electronic supplementary information (ESI) available: Particle size distribution by DLS and TEM images. See DOI: 10.1039/c1nr11401h

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. Avidin-biotin capped mesoporous silica nanoparticles as an ion-responsive release system to determine lead(II).

    PubMed

    Song, Weiling; Li, Jingyu; Li, Qing; Ding, Wenyao; Yang, Xiaoyan

    2015-02-15

    We have developed DNAzyme-functionalized silica nanoparticles for the rapid, sensitive, and selective detection of lead ion (Pb(2+)). The specific binding between avidin and biotinylated DNAzymes was used to cap the pore of dye-trapped silica nanoparticles. In the presence of Pb(2+), DNAzymes were catalytically cleaved to uncap the pore, releasing the dye cargo with detectable enhancements of fluorescence signal. This method enables rapid (15 min) and sensitive (limit of detection=8.0 nM) detection. Moreover, the Pb(2+)-responsive behavior shows high selectivity with other metal ions. The superior properties of the as-designed DNAzyme-functionalized silica nanoparticles can be attributed to the large loading capacity and highly ordered pore structure of mesoporous silica nanoparticles as well as the catalytical cleaving of DNAzymes with Pb(2+). The recoveries obtained by standard Pb(II) addition to real samples-tap water, commercial mineral water, and lake water-were all from 98 to 101%. Our design serves as a new prototype for metal-ion sensing systems, and it also has promising potential for detection of various targets in stimulus-release systems. PMID:25447495

  3. 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

  4. 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.

  5. Affibody-functionalized gold-silica nanoparticles for Raman molecular imaging of the epidermal growth factor receptor.

    PubMed

    Jokerst, Jesse V; Miao, Zheng; Zavaleta, Cristina; Cheng, Zhen; Gambhir, Sanjiv S

    2011-03-01

    The affibody functionalization of fluorescent surface-enhanced Raman scattering gold-silica nanoparticles as multimodal contrast agents for molecular imaging specific to epidermal growth factor receptor (EGFR) is reported. This nanoparticle bioconjugate reports EGFR-positive A431 tumors with a signal nearly 35-fold higher than EGFR-negative MDA-435S tumors. The low-level EGFR expression in adjacent healthy tissue is 7-fold lower than in the positive tumors. Validation via competitive inhibition reduces the signal by a factor of six, and independent measurement of EGFR via flow cytometry correlates at R(2) = 0.92. PMID:21302357

  6. 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.

  7. 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.

  8. Gold Functionalized Mesoporous Silica Nanoparticle Mediated Protein and DNA Codelivery to Plant Cells Via the Biolistic Method

    SciTech Connect

    Martin-Ortigosa, Susana; Valenstein, Justin S.; Lin, Victor S.-Y.; Trewyn, Brian G.; Wang, Kan

    2012-09-11

    The synthesis and characterization of a gold nanoparticle functionalized mesoporous silica nanoparticle (Au-MSN) platform for codelivery of proteins and plasmid DNA to plant tissues using a biolistic particle delivery system is reported. The in vitro uptake and release profiles of fluorescently labeled bovine serum albumin (BSA) and enhanced green fluorescent protein (eGFP) are investigated. As a proof-of-concept demonstration, Au-MSN with large average pore diameters (10 nm) are shown to deliver and subsequently release proteins and plasmid DNA to the same cell after passing through the plant cell wall upon bombardment. Release of fluorescent eGFP indicates the delivery of active, non-denatured proteins to plant cells. This advance represents the first example of biolistic-mediated codelivery of proteins and plasmid DNA to plant cells via gold-functionalized MSN and provides a powerful tool for both fundamental and applied research of plant sciences.

  9. 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.

  10. 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

  11. 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.

  12. Heparinized magnetic mesoporous silica nanoparticles as multifunctional growth factor delivery carriers

    NASA Astrophysics Data System (ADS)

    Wu, Qiang; Liu, Chaoqun; Fan, Luna; Shi, Jiahua; Liu, Zhiqiang; Li, Ruifang; Sun, Liwei

    2012-12-01

    Well-defined magnetic mesoporous silica nanoparticles (MMSNs) with a core/shell structure were prepared via a one pot synthesis. Sphere-like magnetite aggregates were obtained as cores of the final nanoparticles by assembly in the presence of polyvinyl pyrrolidone and cetyltrimethylammonium bromide. The nanoparticles have the property of superparamagnetism with a saturation magnetization value of 20.3 emu g-1. In addition, the combination of heparin and fluorescence-labeled MMSNs endows the resultant particles (denoted as MFMSNs-HP) with magnetism and fluorescence properties, excellent dispersity in the buffer solutions and cell culture media, anticoagulant activity in the blood stream, and the controlled release of basic fibroblast growth factor (bFGF). Furthermore, the bFGF cell viability assays indicate that MFMSNs-HP has nearly no toxicity to human umbilical vein endothelial cells (HUVEC) up to a concentration of 200 μg ml-1, and the proliferation activity of bFGF incorporated into MFMSNs-HP could be retained for at least 6 days. All of these suggest that MFMSNs-HP may serve as a multifunctional carrier for the delivery of growth factors.

  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. 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%.

  15. 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

  16. 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

  17. 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

  18. Red Fluorescent Carbon Nanoparticle-Based Cell Imaging Probe.

    PubMed

    Ali, Haydar; Bhunia, Susanta Kumar; Dalal, Chumki; Jana, Nikhil R

    2016-04-13

    Fluorescent carbon nanoparticle-based probes with tunable visible emission are biocompatible, environment friendly and most suitable for various biomedical applications. However, synthesis of red fluorescent carbon nanoparticles and their transformation into functional nanoparticles are very challenging. Here we report red fluorescent carbon nanoparticle-based nanobioconjugates of <25 nm hydrodynamic size and their application as fluorescent cell labels. Hydrophobic carbon nanoparticles are synthesized via high temperature colloid-chemical approach and transformed into water-soluble functional nanoparticles via coating with amphiphilic polymer followed by covalent linking with desired biomolecules. Following this approach, carbon nanoparticles are functionalized with polyethylene glycol, primary amine, glucose, arginine, histidine, biotin and folic acid. These functional nanoparticles can be excited with blue/green light (i.e., 400-550 nm) to capture their emission spanning from 550 to 750 nm. Arginine and folic acid functionalized nanoparticles have been demonstrated as fluorescent cell labels where blue and green excitation has been used for imaging of labeled cells. The presented method can be extended for the development of carbon nanoparticle-based other bioimaging probes. PMID:27011336

  19. 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.

  20. 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.

  1. An efficient core-shell fluorescent silica nanoprobe for ratiometric fluorescence detection of pH in living cells.

    PubMed

    Fu, Jingni; Ding, Changqin; Zhu, Anwei; Tian, Yang

    2016-08-01

    Intracellular pH plays a vital role in cell biology, including signal transduction, ion transport and homeostasis. Herein, a ratiometric fluorescent silica probe was developed to detect intracellular pH values. The pH sensitive dye fluorescein isothiocyanate isomer I (FITC), emitting green fluorescence, was hybridized with reference dye rhodamine B (RB), emitting red fluorescence, as a dual-emission fluorophore, in which RB was embedded in a silica core of ∼40 nm diameter. Moreover, to prevent fluorescence resonance energy transfer between FITC and RB, FITC was grafted onto the surface of core-shell silica colloidal particles with a shell thickness of 10-12 nm. The nanoprobe exhibited dual emission bands centered at 517 and 570 nm, under single wavelength excitation of 488 nm. RB encapsulated in silica was inert to pH change and only served as reference signals for providing built-in correction to avoid environmental effects. Moreover, FITC (λem = 517 nm) showed high selectivity toward H(+) against metal ions and amino acids, leading to fluorescence variation upon pH change. Consequently, variations of the two fluorescence intensities (Fgreen/Fred) resulted in a ratiometric pH fluorescent sensor. The specific nanoprobe showed good linearity with pH variation in the range of 6.0-7.8. It can be noted that the fluorescent silica probe demonstrated good water dispersibility, high stability and low cytotoxicity. Accordingly, imaging and biosensing of pH variation was successfully achieved in HeLa cells. PMID:27291898

  2. 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

  3. 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

  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. Laser-induced fluorescence of fused silica irradiated by ArF excimer laser

    SciTech Connect

    Zhang Haibo; Yuan Zhijun; Zhou Jun; Dong Jingxing; Wei Yunrong; Lou Qihong

    2011-07-01

    Laser-induced fluorescence (LIF) of high-purity fused silica irradiated by ArF excimer laser is studied experimentally. LIF bands of the fused silica centered at 281 nm, 478 nm, and 650 nm are observed simultaneously. Furthermore, the angular distribution of the three fluorescence peaks is examined. Microscopic image of the laser modified fused silica indicates that scattering of the generated fluorescence by laser-induced damage sites is the main reason for the angular distribution of LIF signals. Finally, the dependence of LIF signals intensities of the fused silica on laser power densities is presented. LIF signals show a squared power density dependence, which indicates that laser-induced defects are formed mainly via two-photon absorption processes.

  8. Nanometer fluorescent hybrid silica particle as ultrasensitive and photostable biological labels.

    PubMed

    Yang, Huang-Hao; Qu, Hui-Ying; Lin, Peng; Li, Shun-Hua; Ding, Ma-Tai; Xu, Jin-Gou

    2003-05-01

    Nanometer-sized fluorescent hybrid silica (NFHS) particles were prepared for use as sensitive and photostable fluorescent probes in biological staining and diagnostics. The first step of the synthesis involves the covalent modification of 3-aminopropyltrimethoxysilane with an organic fluorophore, such as fluorescein isothiocyanate, under N2 atmosphere for getting a fluorescent silica precursor. Then the NFHS particles, with a diameter of well below 40 nm, were prepared by controlled hydrolysis of the fluorescent silica precursor with tetramethoxysilane (TMOS) using the reverse micelle technique. The fluorophores are dispersed homogeneously in the silica network of the NFHS particles and well protected from the environmental oxygen. Furthermore, since the fluorophores are covalently bound to the silica network, there is no migration, aggregation and leakage of the fluorophores. In comparison with common single organic fluorophores, these particle probes are brighter, more stable against photobleaching and do not suffer from intermittent on/off light emission (blinking). We have used these newly developed NFHS particles as a fluorescent marker to label antibodies, using silica immobilization method, for the immunoassay of human alpha-fetoprotein (AFP). The detection limit of this method was down to 0.05 ng mL(-1) under our current experimental conditions. We think this material would attract much attention and be applied widely in biotechnology. PMID:12790198

  9. Biomedical imaging of colorectal cancer by near infrared fluorescent nanoparticles.

    PubMed

    Tivony, Ran; Larush, Liraz; Sela-Tavor, Osnat; Magdassi, Shlomo

    2014-06-01

    In this paper we describe the preparation of novel Near Infrared (NIR) fluorescent nanoparticles for application in medical imaging of colorectal tumors. The nanoparticles are prepared by using only non-covalent binding processes of molecules which are approved for clinical use. The preparation process is based on the precipitation of a polycation, Eudragit-RS, followed by sequential adsorption of a blocking protein, sodium caseinate, NIR fluorescent dye, Indocyanine Green (ICG) and optionally, a targeting molecule, anti-CEA antibody. Fluorescence measurements have shown that these nanoparticles have higher resistance to photobleaching and higher quantum yield relatively to free ICG. Imaging experiments in orthotopic colorectal cancer mice models have shown that these fluorescent nanoparticles are capable of binding to LS174T human colon tumors in vivo with high specificity, even without the targeting molecule. These nanoparticles, composed of all FDA approved materials, open the way to clinical bioimaging and diagnostics of colon cancer. PMID:24749398

  10. 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

  11. Horseradish peroxidase-immobilized magnetic mesoporous silica nanoparticles as a potential candidate to eliminate intracellular reactive oxygen species

    NASA Astrophysics Data System (ADS)

    Shen, Yajing; Zhang, Ye; Zhang, Xiang; Zhou, Xiuhong; Teng, Xiyao; Yan, Manqing; Bi, Hong

    2015-02-01

    Horseradish peroxidase-immobilized magnetic mesoporous silica nanoparticles (MMSNs-HRP) have been synthesized by a NHS/EDC coupling between the amino groups of horseradish peroxidase (HRP) and the carboxyl groups on the MMSNs surface. It is found that the immobilized HRP on MMSNs still retain high activity and the MMSNs-HRP can eliminate the reactive oxygen species (ROS) in Chinese hamster ovary (CHO) cells induced by the addition of H2O2 aqueous solution. Further, the fluorescent MMSN-HRP-CD nanoparticles have been prepared by attaching biocompatible, fluorescent carbon dots (CDs) to MMSNs-HRP. We have also investigated the effect of an applied magnetic field on cellular uptake of MMSNs-HRP-CDs and found that the internalization of MMSNs-HRP-CDs by CHO cells could be enhanced within 2 hours under the magnetic field. This work provides us with a novel and efficient method to eliminate ROS in living cells by using HRP-immobilized nanoparticles.Horseradish peroxidase-immobilized magnetic mesoporous silica nanoparticles (MMSNs-HRP) have been synthesized by a NHS/EDC coupling between the amino groups of horseradish peroxidase (HRP) and the carboxyl groups on the MMSNs surface. It is found that the immobilized HRP on MMSNs still retain high activity and the MMSNs-HRP can eliminate the reactive oxygen species (ROS) in Chinese hamster ovary (CHO) cells induced by the addition of H2O2 aqueous solution. Further, the fluorescent MMSN-HRP-CD nanoparticles have been prepared by attaching biocompatible, fluorescent carbon dots (CDs) to MMSNs-HRP. We have also investigated the effect of an applied magnetic field on cellular uptake of MMSNs-HRP-CDs and found that the internalization of MMSNs-HRP-CDs by CHO cells could be enhanced within 2 hours under the magnetic field. This work provides us with a novel and efficient method to eliminate ROS in living cells by using HRP-immobilized nanoparticles. Electronic supplementary information (ESI) available: TEM image of CDs, BET XRD

  12. 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

  13. Highly Flexible Platform for Tuning Surface Properties of Silica Nanoparticles and Monitoring Their Biological Interaction.

    PubMed

    Ojea-Jiménez, Isaac; Urbán, Patricia; Barahona, Francisco; Pedroni, Matteo; Capomaccio, Robin; Ceccone, Giacomo; Kinsner-Ovaskainen, Agnieszka; Rossi, François; Gilliland, Douglas

    2016-02-24

    The following work presents a simple, reliable and scalable seeding-growth methodology to prepare silica nanoparticles (SiO2 NPs) (20, 30, 50 and 80 nm) directly in aqueous phase, both as plain- as well as fluorescent-labeled silica. The amount of fluorescent label per particle remained constant regardless of size, which facilitates measurements in terms of number-based concentrations. SiO2 NPs in dispersion were functionalized with an epoxysilane, thus providing a flexible platform for the covalent linkage of wide variety of molecules under mild experimental conditions. This approach was validated with ethylenediamine, two different amino acids and three akylamines to generate a variety of surface modifications. Accurate characterization of particle size, size distributions, morphology and surface chemistry is provided, both for as-synthesized particles and after incubation in cell culture medium. The impact of physicochemical properties of SiO2 NPs was investigated with human alveolar basal epithelial cells (A549) such as the effect in cytotoxicity, cell internalization and membrane interaction. PMID:26779668

  14. Monolayer formation of luminescent germanium nanoparticles on silica surface in aqueous buffer solution.

    PubMed

    Shirahata, Naoto

    2014-03-01

    The present paper reports monolayer formation of germanium nanoparticles (Ge NPs) on silica substrate. The NPs were prepared by hydride reduction of GeCl4, which is encapsulated with an inverse micelle of dimethyldioctylammonium bromide, with lithium aluminum hydride, and subsequent hydrogermylation of allylamine in the presence of platinum catalyst. The resultant NPs showed the blue photoluminescence property. Due to the terminal amine, the NPs were soluble highly in aqueous buffer solution. To fabricate a monolayer of Ge NPs, the chemical reactivity of the NPs was studied using a multi-functional microarray in which different kinds of siloxane monolayers were periodically aligned on a silica substrate. We observed using fluorescence microscope whether the terminal amines of the NPs recognize the specific monolayers in the microarray. In terms of fluorescence observation, the entire surface of the monolayer-covered microsize-domains emits uniformly the blue light. This suggests a high degree of coverage of the luminescent NPs covering over the monolayer regions in the microarray, and implies the non-occurrence of quenching through energy transfer between adjacent NPs. PMID:24745276

  15. Magnetic and fluorescent core-shell nanoparticles for ratiometric pH sensing

    NASA Astrophysics Data System (ADS)

    Lapresta-Fernández, Alejandro; Doussineau, Tristan; Dutz, Silvio; Steiniger, Frank; Moro, Artur J.; Mohr, Gerhard J.

    2011-10-01

    This paper describes the preparation of nanoparticles composed of a magnetic core surrounded by two successive silica shells embedding two fluorophores, showing uniform nanoparticle size (50-60 nm in diameter) and shape, which allow ratiometric pH measurements in the pH range 5-8. Uncoated iron oxide magnetic nanoparticles (~10 nm in diameter) were formed by the coprecipitation reaction of ferrous and ferric salts. Then, they were added to a water-in-oil microemulsion where the hydrophilic silica shells were obtained through hydrolysis and condensation of tetraethoxyorthosilicate together with the corresponding silylated dye derivatives—a sulforhodamine was embedded in the inner silica shell and used as the reference dye while a pH-sensitive fluorescein was incorporated in the outer shell as the pH indicator. The magnetic nanoparticles were characterized using vibrating sample magnetometry, dynamic light scattering, transmission electron microscopy, x-ray diffraction and Fourier transform infrared spectroscopy. The relationship between the analytical parameter, that is, the ratio of fluorescence between the sensing and reference dyes versus the pH was adjusted to a sigmoidal fit using a Boltzmann type equation giving an apparent pKa value of 6.8. The fluorescence intensity of the reference dye did not change significantly (~3.0%) on modifying the pH of the nanoparticle dispersion. Finally, the proposed method was statistically validated against a reference procedure using samples of water and physiological buffer with 2% of horse serum, indicating that there are no significant statistical differences at a 95% confidence level.

  16. 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.

  17. 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

  18. Bare magnetic nanoparticles as fluorescence quenchers for detection of thrombin.

    PubMed

    Yu, Jiemiao; Yang, Liangrong; Liang, Xiangfeng; Dong, Tingting; Liu, Huizhou

    2015-06-21

    Rapid and sensitive detection of thrombin has very important significance in clinical diagnosis. In this work, bare magnetic iron oxide nanoparticles (magnetic nanoparticles) without any modification were used as fluorescence quenchers. In the absence of thrombin, a fluorescent dye (CY3) labeled thrombin aptamer (named CY3-aptamer) was adsorbed on the surface of magnetic nanoparticles through interaction between a phosphate backbone of the CY3-aptamer and hydroxyl groups on the bare magnetic nanoparticles in binding solution, leading to fluorescence quenching. Once thrombin was introduced, the CY3-aptamer formed a G-quartet structure and combined with thrombin, which resulted in the CY3-aptamer being separated from the magnetic nanoparticles and restoration of fluorescence. This proposed assay took advantage of binding affinity between the CY3-aptamer and thrombin for specificity, and bare magnetic nanoparticles for fluorescence quenching. The fluorescence signal had a good linear relationship with thrombin concentration in the range of 1-60 nM, and the limit of detection for thrombin was estimated as low as 0.5 nM. Furthermore, this method could be applied for other target detection using the corresponding fluorescence labeled aptamer. PMID:25894923

  19. 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.

  20. Antifouling surfaces for proteins labeled with dye-doped silica nanoparticles.

    PubMed

    Wang, Hui; Tong, Qi; Yan, Mingdi

    2013-01-01

    We report that proteins labeled with fluorescein-doped silica nanoparticles (FSNPs) showed drastically different fouling behavior than those labeled with the fluorescein dye. Arrays of polymer films were covalently immobilized on silicon wafers and were treated with protein conjugated on FSNPs. Fluorescence imaging showed that the protein-FSNP conjugate adsorbed strongly on hydrophilic polymers such as poly(ethylene oxide) (PEO) and weakly on hydrophobic polymers such as polystyrene (PS), and the extent of adsorption decreased with increasing hydrophobicity of the polymer film. Thus, carbohydrate microarrays probed with FSNP-labeled lectin showed significantly enhanced signals when PS was used as the antifouling coating than when PEO was used, or when using bovine serum albumin as the blocking agent. PMID:23236953

  1. Antifouling Surfaces for Proteins Labeled with Dye-Doped Silica Nanoparticles

    PubMed Central

    Wang, Hui; Tong, Qi; Yan, Mingdi

    2012-01-01

    We report that proteins labeled with fluorescein-doped silica nanoparticles (FSNPs) showed drastically different fouling behavior than those labeled with the fluorescein dye. Arrays of polymer films were covalently immobilized on silicon wafers, and were treated with protein conjugated on FSNPs. Fluorescence imaging showed that the protein-FSNP conjugate adsorbed strongly on hydrophilic polymers such as poly(ethylene oxide) (PEO) and weakly on hydrophobic polymers such as polystyrene (PS), and the extent of adsorption decreased with increasing hydrophobicity of the polymer film. Thus, carbohydrate microarrays probed with FSNP-labeled lectin showed significantly enhanced signals when PS was used as the antifouling coating than PEO as well as when bovine serum albumin was used as the blocking agent. PMID:23236953

  2. Advances in Peptide Functionalization on Mesoporous Silica Nanoparticles for Controlled Drug Release.

    PubMed

    Hu, Jing-Jing; Xiao, Dong; Zhang, Xian-Zheng

    2016-07-01

    During the last decade, using versatile, promising, and fascinating mesoporous silica nanoparticles (MSNs) as site-specific and stimuli-responsive drug delivery systems (DDSs) has received concentrated research interest. As one of the most attractive surface modification units, peptides have inherent bioactivity, biodegradability and biocompatibility. Recent progresses in the utilization of versatile peptides for surface functionalization of MSNs to achieve cell-specific targeting, fluorescence imaging, and intracellular diagnosis and treatment of tumors are summarized in this review. The various functional peptides decorated on the MSNs are introduced and classified into three types, including targeting peptides, stimuli-responsive peptides and multifunctional chimeric peptides. The limitations and challenges of peptide modified MSNs and their potential applications are further discussed. PMID:27152737

  3. Probing the Microenvironment in the Confined Pores of Mesoporous Silica Nanoparticles

    PubMed Central

    2015-01-01

    The microenvironment inside of the pores of mesoporous silica nanoparticles is probed using spectroscopic techniques. The probe molecules are sealed inside of the pores by a nanovalve system that is capable of controlling the access to the pore and ensuring the exclusive probing of the pore environment without any interference from the probe molecules on the outer surface of the particles or from the surrounding solution. Rigidochromism studies are used to evaluate the rigidity of the solvent matrix inside of the pore, and dynamic fluorescence anisotropy experiments are employed to determine the rotational diffusion freedom of the probe molecule. The data show that those probe molecules are neither completely free to move nor tightly attached to the pore wall, and their mobility is changed by altering the charge of the pore wall. PMID:24803992

  4. 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

  5. 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

  6. 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

  7. Spectral variation of fluorescence lifetime near single metal nanoparticles

    PubMed Central

    Li, Jia; Krasavin, Alexey V.; Webster, Linden; Segovia, Paulina; Zayats, Anatoly V.; Richards, David

    2016-01-01

    We explore the spectral dependence of fluorescence enhancement and the associated lifetime modification of fluorescent molecules coupled to single metal nanoparticles. Fluorescence lifetime imaging microscopy and single-particle dark-field spectroscopy are combined to correlate the dependence of fluorescence lifetime reduction on the spectral overlap between the fluorescence emission and the localised surface plasmon (LSP) spectra of individual gold nanoparticles. A maximum lifetime reduction is observed when the fluorescence and LSP resonances coincide, with good agreement provided by numerical simulations. The explicit comparison between experiment and simulation, that we obtain, offers an insight into the spectral engineering of LSP mediated fluorescence and may lead to optimized application in sensing and biomedicine. PMID:26876780

  8. Simultaneous spectroscopic measurements of the interior temperature and induced cargo release from pore-restricted mesoporous silica nanoparticles.

    PubMed

    Dong, Juyao; Zink, Jeffrey I

    2016-05-19

    Temperature changes initiated within nano structures are being increasingly used to externally activate responsive delivery vehicles. Yet, the precise measurement of the nano environment temperature increase and its correlation with the induced macroscopic cargo release are difficult to achieve. In this study, we focus on a photothermally activated drug delivery system based on mesoporous silica nanoparticles, and use an optical nanothermometer - NaYF4:Yb(3+),Er(3+) crystals - for a ratiometric temperature measurement. Using fluorescent dyes as the payload molecule, both the nanoparticle interior temperature change and the macroscopic cargo release amount are monitored simultaneously by fluorescent spectroscopy. We found that the cargo release lags the temperature increase by about 5 min, revealing the threshold temperature that the particles have to reach before a substantial release could happen. Using this spectroscopic method, we are able to directly compare and correlate a nano environment event with its stimulated macroscopic results. PMID:27150579

  9. Distance and wavelength dependent quenching of molecular fluorescence by Au@SiO2 core-shell nanoparticles.

    PubMed

    Reineck, Philipp; Gómez, Daniel; Ng, Soon Hock; Karg, Matthias; Bell, Toby; Mulvaney, Paul; Bach, Udo

    2013-08-27

    Gold nanoparticles and nearby fluorophores interact via electromagnetic coupling upon light excitation. We determine the distance and wavelength dependence of this coupling theoretically and experimentally via steady-state and time-resolved fluorescence spectroscopy. For the first time, the fluorescence quenching of four different dye molecules, which absorb light at different wavelengths across the visible spectrum and into the near-infrared, is studied using a rigid silica shell as a spacer. A comprehensive experimental determination of the distance dependence from complete quenching to no coupling is carried out by a systematic variation of the silica shell thickness. Electrodynamic theory predicts the observed quenching quantitatively in terms of energy transfer from the molecular emitter to the gold nanoparticle. The plasmonic field enhancement in the vicinity of the 13 nm gold nanoparticles is calculated as a function of distance and excitation wavelength and is included in all calculations. Relative radiative and energy transfer rates are determined experimentally and are in good agreement with calculated rates. We demonstrate and quantify the severe effect of dye-dye interactions on the fluorescence properties of dyes attached to the surface of a silica nanoparticle in control experiments. This allows us to determine the experimental conditions, under which dye-dye interactions do not affect the experimental results. PMID:23713513

  10. 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

  11. 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.

  12. Hybrid semiconducting polymer nanoparticles as polarization-sensitive fluorescent probes

    PubMed Central

    Zeigler, Maxwell B.; Sun, Wei; Rong, Yu; Chiu, Daniel T.

    2013-01-01

    Much work has been done on collapsed chains of conjugated semiconducting polymers and their applications as fluorescent probes or sensors. On surfaces spin-coated with semiconducting polymers, excitation energy transfer along the polymer backbone can be used to quickly and efficiently funnel energy to chromophores with localized energy minima. If each chromophore is immobilized within its matrix, this can result in large fluorescence anisotropy. Through nanoprecipitation of a matrix polymer blended at low mass ratios with short-chain, hydrophobic, fluorescent semiconducting polymers, we take advantage of this large fluorescence anisotropy to make polarization-sensitive nanoparticles. These nanoparticles are small at approximately 7 nm in diameter; exhibit a high quantum yield of 0.75; and are easily functionalized to bind to protein targets. By exciting the nanoparticles with polarized light on a wide-field fluorescence microscope, we are able to monitor not only protein location, but also changes in their orientation. PMID:23895535

  13. 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

  14. Simultaneous spectroscopic measurements of the interior temperature and induced cargo release from pore-restricted mesoporous silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Dong, Juyao; Zink, Jeffrey I.

    2016-05-01

    Temperature changes initiated within nano structures are being increasingly used to externally activate responsive delivery vehicles. Yet, the precise measurement of the nano environment temperature increase and its correlation with the induced macroscopic cargo release are difficult to achieve. In this study, we focus on a photothermally activated drug delivery system based on mesoporous silica nanoparticles, and use an optical nanothermometer - NaYF4:Yb3+,Er3+ crystals - for a ratiometric temperature measurement. Using fluorescent dyes as the payload molecule, both the nanoparticle interior temperature change and the macroscopic cargo release amount are monitored simultaneously by fluorescent spectroscopy. We found that the cargo release lags the temperature increase by about 5 min, revealing the threshold temperature that the particles have to reach before a substantial release could happen. Using this spectroscopic method, we are able to directly compare and correlate a nano environment event with its stimulated macroscopic results.Temperature changes initiated within nano structures are being increasingly used to externally activate responsive delivery vehicles. Yet, the precise measurement of the nano environment temperature increase and its correlation with the induced macroscopic cargo release are difficult to achieve. In this study, we focus on a photothermally activated drug delivery system based on mesoporous silica nanoparticles, and use an optical nanothermometer - NaYF4:Yb3+,Er3+ crystals - for a ratiometric temperature measurement. Using fluorescent dyes as the payload molecule, both the nanoparticle interior temperature change and the macroscopic cargo release amount are monitored simultaneously by fluorescent spectroscopy. We found that the cargo release lags the temperature increase by about 5 min, revealing the threshold temperature that the particles have to reach before a substantial release could happen. Using this spectroscopic method, we are

  15. 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

  16. 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

  17. 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

  18. 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.

  19. 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

  20. 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

  1. 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

  2. Luminescent studies of fluorescent chromophore-doped silica aerogels for flat panel display applications

    SciTech Connect

    Glauser, S.A.C.; Lee, H.W.H.

    1997-04-01

    The remarkable optical and electronic properties of doped and undoped silica aerogels establish their utility as unique, mulitfunctional host materials for fluorescent dyes and other luminescent materials for display and imaging applications. We present results on the photoluminescence, absorption, and photoluminescence excitation spectra of undoped silica aerogels and aerogels doped with Er{sup 3+}, rhodamine 6G (R6G), and fluorescein. 4 refs., 12 figs.

  3. Plasmon-Enhanced Raman and Fluorescence Spectroscopy with Gold and Silver Nanoparticles

    NASA Astrophysics Data System (ADS)

    Guerrero Hernandez, Ariel Rodrigo

    This thesis contains five major contributions to the field of plasmon-enhanced spectroscopy. We start with the report of a unique SERS study of the amino acid hydroxyproline and a deuterated analogue. Later, we move on to the exploration of a major new research path known as shell-isolated nanoparticle-enhanced fluorescence (SHINEF), consisting in the application of silica-shelled noble metal nanoparticles to achieve surface-enhanced fluorescence. The proof of concept of this technique is explained in one chapter. The two following chapters are devoted to the exploration of the plasmonic properties of SHINEF: spectral profile modification showing the close relationship between the observed enhanced fluorescence and the nanoparticle scattering. The SHIN particles are employed to experimentally prove the relationship between the SEF and SERS enhancement factors, theoretically predicted before, but never verified experimentally until now. The thesis ends with an investigation, in aqueous solutions, of several different factors that play a role in the origin of SEF, showing greater enhancement for SHINEF after inducing nanoparticle aggregation.

  4. 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

  5. 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

  6. 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

  7. Effects of Silica Nanoparticle Supported Ionic Liquid as Additive on Thermal Reversibility of Human Carbonic Anhydrase II

    PubMed Central

    Fallahbagheri, Azadeh; Saboury, Ali Akbar; Ma'mani, Leila; Taghizadeh, Mohammad; Khodarahmi, Reza; Ranjbar, Samira; Bohlooli, Mousa; Shafiee, Abbas; Foroumadi, Alireza; Sheibani, Nader; Moosavi-Movahedi, Ali Akbar

    2013-01-01

    Silica nanoparticle supported imidazolium ionic liquid [SNImIL] was synthesized and utilized as a biocompatible additive for studying the thermal reversibility of human carbonic anhydrase II (HCA II). For this purpose, we prepared additive by modification of nanoparticles through the grafting of ionic liquids on the surface of nanoparticles (SNImIL). The SNImIL were fully characterized by Fourier Transform Infrared spectroscopy, scanning electron microscopy and thermo gravimetric analysis. The characterization of HCA II was investigated by various techniques including UV–Vis and ANS fluorescence spectrophotometry, differential scanning calorimetry, and docking study. SNImIL induced disaggregation, enhanced protein stability and increased thermal reversibility of HCA II by up to 42% at pH 7.75. PMID:22829053

  8. Fluorescence of pyrene in inhomogeneous media containing silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Romanovskaya, G. I.

    2014-05-01

    Pyrene fluorescence in inhomogeneous media based on ionic detergents containing silver nanoparticles with different morphologies is investigated. An increase in pyrene monomer emissions in the spectral range of 400-500 nm is observed, due to the resonance between electronic transitions in pyrene molecules in that region and the plasmonic oscillations of silver nanoparticles.

  9. Laser-induced fluorescence reader with a turbidimetric system for sandwich-type immunoassay using nanoparticles.

    PubMed

    Kim, Y H; Lim, H B

    2015-07-01

    A unique laser-induced fluorescence (LIF) reader equipped with a turbidimetric system was developed for a sandwich-type immunoassay using nanoparticles. The system was specifically designed to reduce experimental error caused by particle loss, aggregation and sinking, and to improve analytical performance through ratiometric measurement of the fluorescence with respect to the turbidimetric absorbance. For application to determine the concentration of salinomycin, magnetic nanoparticles (MNPs) and FITC-doped silica nanoparticles (colored balls) immobilized with antibody were synthesized for magnetic extraction and for tagging as a fluorescence probe, respectively. The detection limit of about 39 pg mL(-1) was obtained, which was an improvement of about 2-fold compared to that obtained without employment of the turbidimetric system. Calibration linearity and sensitivity were also improved, with increase from 0.8601 to 0.9905 in the R(2)-coefficient and by 1.92-fold for the curve slope, respectively. The developed LIF reader has the potential to be used for fluorescence measurements using various nanomaterials, such as quantum dots. PMID:26088773

  10. 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

  11. 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

  12. 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

  13. 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

  14. Utilizing the protein corona around silica nanoparticles for dual drug loading and release

    NASA Astrophysics Data System (ADS)

    Shahabi, Shakiba; Treccani, Laura; Dringen, Ralf; Rezwan, Kurosch

    2015-10-01

    A protein corona forms spontaneously around silica nanoparticles (SNPs) in serum-containing media. To test whether this protein corona can be utilized for the loading and release of anticancer drugs we incorporated the hydrophilic doxorubicin, the hydrophobic meloxicam as well as their combination in the corona around SNPs. The application of corona-covered SNPs to osteosarcoma cells revealed that drug-free particles did not affect the cell viability. In contrast, SNPs carrying a protein corona with doxorubicin or meloxicam lowered the cell proliferation in a concentration-dependent manner. In addition, these particles had an even greater antiproliferative potential than the respective concentrations of free drugs. The best antiproliferative effects were observed for SNPs containing both doxorubicin and meloxicam in their corona. Co-localization studies revealed the presence of doxorubicin fluorescence in the nucleus and lysosomes of cells exposed to doxorubicin-containing coated SNPs, suggesting that endocytotic uptake of the SNPs facilitates the cellular accumulation of the drug. Our data demonstrate that the protein corona, which spontaneously forms around nanoparticles, can be efficiently exploited for loading the particles with multiple drugs for therapeutic purposes. As drugs are efficiently released from such particles they may have a great potential for nanomedical applications.A protein corona forms spontaneously around silica nanoparticles (SNPs) in serum-containing media. To test whether this protein corona can be utilized for the loading and release of anticancer drugs we incorporated the hydrophilic doxorubicin, the hydrophobic meloxicam as well as their combination in the corona around SNPs. The application of corona-covered SNPs to osteosarcoma cells revealed that drug-free particles did not affect the cell viability. In contrast, SNPs carrying a protein corona with doxorubicin or meloxicam lowered the cell proliferation in a concentration

  15. 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

  16. 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

  17. 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.

  18. 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

  19. Novel functionalized fluorescent polymeric nanoparticles for immobilization of biomolecules

    NASA Astrophysics Data System (ADS)

    Jain, Swati; Chattopadhyay, Sruti; Jackeray, Richa; Abid, C. K. V. Zainul; Singh, Harpal

    2013-07-01

    Novel, size controlled fluorescent polymeric nanoparticles (FPNP) were synthesized having acetoacetoxy functionality on the surface for immobilization of biomolecules which can be utilized as biomarkers and labels in fluoroimmunoassays. Core-shell nanoparticles of poly(styrene, St-methyl methacrylate, MMA-acetoacetoxy ethyl methacrylate, AAEM), stabilized by various concentrations of surfactant, sodium lauryl sulphate (SLS), were obtained by facile miniemulsion co-polymerization encapsulated with pyrene molecules in their hydrophobic core. Analytical, spectroscopic and imaging characterization techniques revealed the formation of stable, monodisperse, spherical nano sized particles exhibiting high luminescence properties. Particles with 1% SLS (S1) showed good dispersion stability and fluorescence intensity and were chosen as ideal candidates for further immobilization studies. Steady state fluorescence studies showed 10 times higher fluorescence intensity of S1 nanoparticles than that of pyrene solution in solvent-toluene at the same concentration. Environmental factors such as pH, ionic strength and time were found to have no effect on fluorescence intensity of FPNPs. Surface β-di-ketone groups were utilized for the covalent immobilization of enzyme conjugated antibodies without any activation or pre-treatment of nanoparticles.Novel, size controlled fluorescent polymeric nanoparticles (FPNP) were synthesized having acetoacetoxy functionality on the surface for immobilization of biomolecules which can be utilized as biomarkers and labels in fluoroimmunoassays. Core-shell nanoparticles of poly(styrene, St-methyl methacrylate, MMA-acetoacetoxy ethyl methacrylate, AAEM), stabilized by various concentrations of surfactant, sodium lauryl sulphate (SLS), were obtained by facile miniemulsion co-polymerization encapsulated with pyrene molecules in their hydrophobic core. Analytical, spectroscopic and imaging characterization techniques revealed the formation of stable

  20. 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

  1. 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

  2. Aqueous ferrofluid of magnetite nanoparticles: Fluorescence labeling and magnetophoretic control.

    PubMed

    Sahoo, Yudhisthira; Goodarzi, Alireza; Swihart, Mark T; Ohulchanskyy, Tymish Y; Kaur, Navjot; Furlani, Edward P; Prasad, Paras N

    2005-03-10

    A method is presented for the preparation of a biocompatible ferrofluid containing dye-functionalized magnetite nanoparticles that can serve as fluorescent markers. This method entails the surface functionalization of magnetite nanoparticles using citric acid to produce a stable aqueous dispersion and the subsequent binding of fluorescent dyes to the surface of the particles. Several ferrofluid samples were prepared and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), BET surface area analysis, transmission electron microscopy (TEM), and SQUID magnetometry. In addition, confocal fluorescence microscopy was used to study the response of the fluorescent nanoparticles to an applied magnetic field and their uptake by cells in vitro. Results are presented on the distribution of particle sizes, the fluorescent and magnetic properties of the nanoparticles, and the nature of their surface bonds. Biocompatible ferrofluids with fluorescent nanoparticles enable optical tracking of basic processes at the cellular level combined with magnetophoretic manipulation and should be of substantial value to researchers engaged in both fundamental and applied biomedical research. PMID:16851439

  3. 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...

  4. 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

  5. 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

  6. 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.

  7. 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

  8. Mesoporous Silica Nanoparticles in Cancer Therapy: Relevance of the Targeting Function.

    PubMed

    Pasqua, Luigi; Leggio, Antonella; Sisci, Diego; Andò, Sebastiano; Morelli, Catia

    2016-01-01

    In the last years, the oncologic research is focusing on the optimization of the clinical approach to the tumor disease, through the development of new therapeutic strategies combining currently used antineoplastic drugs to targeted delivery systems. In fact, due to the drugs poor selectivity for cancer cells, an highly aggressive style of dosing is necessary to eradicate tumors, causing severe toxicity to normal cells. Therefore, localized drug delivery would, ideally, improve the therapeutic efficacy, minimizing side effects. Mesoporous silica nanoparticles (MSNs) have been proposed as a promising class of versatile drug/DNA delivery vehicles, as well as efficient tools for fluorescent cell tracking. To date, the major limitation is that MSNs enter the cells regardless of a target-specific functionalization. Therefore, this review is aimed to give a brief up to date overview on mesoporous silica based-drug delivery vehicles, specifically applied to tumor therapy, giving particular emphasis to the importance of a targeting function grafted on the carrier surface, so to avoid an indiscriminate uptake by cells. PMID:26996622

  9. Bifunctional magnetic-fluorescent nanoparticles: synthesis, characterization, and cell imaging.

    PubMed

    Lu, Yanjiao; Zheng, Yang; You, Shusen; Wang, Feng; Gao, Zhuo; Shen, Jie; Yang, Wantai; Yin, Meizhen

    2015-03-11

    A new type of bifunctional magnetic-fluorescent Fe3O4@SiO2-PDI-PAA/Ca(2+) nanoparticles has been prepared by coating PDI-cored star polymers (PDI-PAA) onto the surface of Fe3O4@SiO2 core-shell nanostructures. The morphology and properties of the composite nanoparticles are investigated by transmission electron microscopy, ultraviolet-visible spectrometry, fluorescence spectrometry, and vibrating sample magnetometry. The composite nanoparticles display a strong red emission and superparamagnetic behavior at room temperature. The cell viability and uptake assays reveal good biocompatibility of these hybrid nanoparticles. Hence, the composite nanoparticles are of potential to be further explored as therapeutic vector in biomedical field. PMID:25691125

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. 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

  16. 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

  17. 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

  18. Mesoporous silica nanoparticles as a compound delivery system in zebrafish embryos

    PubMed Central

    Sharif, Faiza; Porta, Fabiola; Meijer, Annemarie H; Kros, Alexander; Richardson, Michael K

    2012-01-01

    Silica nanoparticles can be efficiently employed as carriers for therapeutic drugs in vitro. Here, we use zebrafish embryos as a model organism to see whether mesoporous silica nanoparticles (MSNPs) can be incorporated to deliver compounds in vivo. We injected 35–40 nL (10 mg/mL) of custom-synthesized, fluorescently-tagged 200 nm MSNPs into the left flank, behind the yolk sac extension, of 2-day-old zebrafish embryos. We tracked the distribution and translocation of the MSNPs using confocal laser scanning microscopy. Some of the particles remained localized at the injection site, whereas others entered the bloodstream and were carried around the body. Embryo development and survival were not significantly affected by MSNP injection. Acridine orange staining revealed that MSNP injections did not induce significant cell death. We also studied cellular immune responses by means of lysC::DsRED2 transgenic embryos. MSNP-injected embryos showed infiltration of the injection site with neutrophils, similar to controls injected with buffer only. In the same embryos, counterstaining with L-plastin antibody for leukocytes revealed the same amount of cellular infiltration of the injection site in embryos injected with MSNPs or with buffer only. Next, we used MSNPs to deliver two recombinant cytokines (macrophage colony-stimulating factor and receptor for necrosis factor ligand) to zebrafish embryos. These proteins are known to activate cells involved in bone remodeling, and this can be detected with the marker tartrate-resistant acid phosphatase. Coinjection of these proteins loaded onto MSNPs produced a significant increase in the number of tartrate-resistant acid phosphatase-positive cells after 2–3 days of injection. Our results show that MSNPs can be used to deliver bioactive compounds into zebrafish larvae without producing higher mortality or gross evidence of teratogenicity. PMID:22605936

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. Towards multifunctional, targeted drug delivery systems using mesoporous silica nanoparticles - opportunities & challenges

    NASA Astrophysics Data System (ADS)

    Rosenholm, Jessica M.; Sahlgren, Cecilia; Lindén, Mika

    2010-10-01

    One of the big challenges of medicine today is to deliver drugs specifically to defected cells. Nanoparticulate drug carriers have the potential to answer to this call, as nanoparticles can cross physiological barriers and access different tissues, and also be provided in a targetable form aimed at enhancing cell specificity of the carrier. Recent developments within material science and strong collaborative efforts crossing disciplinary borders have highlighted the potential of mesoporous silica nanoparticles (MSNs) for such targeted drug delivery. Here we outline recent advances which in this sense push MSNs to the forefront of drug delivery development. Relatively straightforward inside-out tuning of the vehicles, high flexibility, and potential for sophisticated release mechanisms make these nanostructures promising candidates for targeted drug delivery such as `smart' cancer therapies. Moreover, due to the large surface area and the controllable surface functionality of MSNs, they can be controllably loaded with large amounts of drugs and coupled to homing molecules to facilitate active targeting, simultaneously carrying traceable (fluorescent or magnetically active) modalities, also making them highly interesting as theragnostic agents. However, the increased relative surface area and small size, and flexible surface functionalization which is beneficially exploited in nanomedicine, consequently also includes potential risks in their interactions with biological systems. Therefore, we also discuss some safety issues regarding MSNs and highlight how different features of the drug delivery platform influence their behaviour in a biological setting. Addressing these burning questions will facilitate the application of MSNs in nanomedicine.

  4. Utilizing the protein corona around silica nanoparticles for dual drug loading and release.

    PubMed

    Shahabi, Shakiba; Treccani, Laura; Dringen, Ralf; Rezwan, Kurosch

    2015-10-21

    A protein corona forms spontaneously around silica nanoparticles (SNPs) in serum-containing media. To test whether this protein corona can be utilized for the loading and release of anticancer drugs we incorporated the hydrophilic doxorubicin, the hydrophobic meloxicam as well as their combination in the corona around SNPs. The application of corona-covered SNPs to osteosarcoma cells revealed that drug-free particles did not affect the cell viability. In contrast, SNPs carrying a protein corona with doxorubicin or meloxicam lowered the cell proliferation in a concentration-dependent manner. In addition, these particles had an even greater antiproliferative potential than the respective concentrations of free drugs. The best antiproliferative effects were observed for SNPs containing both doxorubicin and meloxicam in their corona. Co-localization studies revealed the presence of doxorubicin fluorescence in the nucleus and lysosomes of cells exposed to doxorubicin-containing coated SNPs, suggesting that endocytotic uptake of the SNPs facilitates the cellular accumulation of the drug. Our data demonstrate that the protein corona, which spontaneously forms around nanoparticles, can be efficiently exploited for loading the particles with multiple drugs for therapeutic purposes. As drugs are efficiently released from such particles they may have a great potential for nanomedical applications. PMID:26377025

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. Green fluorescent protein-doped sol-gel silica planar waveguide to detect organophosphorus compound

    NASA Astrophysics Data System (ADS)

    Enami, Y.; Suye, S.

    2012-02-01

    We report novel living protein-doped planar waveguide, and real-time detection of an organophosphorus compound using a sol-gel silica planar waveguide doped with a green fluorescent protein and an organophosphorus hydrolase on a yeast-cell surface. The waveguide was pumped at 488 nm, and emitted green fluorescence at the far field. The green fluorescent light at 550 nm changed by 50% from the original power 1 min after application of the organophosphorus compound. The results enable the real-time detection of biochemical weapon and insecticide harmful for human body by using an in-line fiber sensor network.

  13. Facile synthesis of fluorescent polymer nanoparticles by covalent modification-nanoprecipitation of amine-reactive ester polymers.

    PubMed

    Lee, Yeonju; Hanif, Sadaf; Theato, Patrick; Zentel, Rudolf; Lim, Jeewoo; Char, Kookheon

    2015-06-01

    Emission wavelength control in fluorescent nanoparticles (NPs) is crucial for their applications. In the case of inorganic quantum dots or dye-impregnated silica NPs, such a control is readily achieved by changing the size of the particles or choosing appropriate fluorescent dyes, respectively. A similar modular approach for controlling the emission wavelength of fluo-rescent polymer NPs, however, is difficult. This article reports on fluorescent polymer NPs, the synthesis of which provides a platform for a modular approach towards the preparation of fluorescent NPs of desired emission wavelength. Atom-transfer radical polymerization (ATRP) is employed to synthesize reactive ester polymers, which are then easily modified with a commercially available dye and subsequently subjected to nanoprecipitation. The resulting NPs, with low size polydispersity, show an enhanced emission quantum yield when compared with the same dye molecules in solution. PMID:25761204

  14. 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.

  15. 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

  16. 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.

  17. Raspberry-like PS/CdTe/Silica Microspheres for Fluorescent Superhydrophobic Materials.

    PubMed

    Chang, Jinghui; Zang, Linlin; Wang, Cheng; Sun, Liguo; Chang, Qing

    2016-12-01

    Superhydrophobic particulate films were fabricated via deposition of raspberry-like fluorescent PS/CdTe/silica microspheres on clean glass substrates and surface modification. Particularly, the fluorescent microspheres were prepared by a kind of modified strategy, namely introducing poly (acrylic acid)-functionalized polystyrene microspheres and thiol-stabilized CdTe quantum dots into a hydrolysis reaction of tetraethoxysilane simultaneously. And through adjusting the reaction parameters, the polystyrene spheres with two particle sizes and three colors of CdTe quantum dots aqueous solution were obtained. Consequently, raspberry-like microspheres consist of polystyrene cores and the composite shells of CdTe quantum dots and silica. These microspheres possess a fluorescent characteristic and form a hierarchical dual roughness which was conductive to superhydrophobicity, and the hydrophobic tests also showed the contact angles of water droplets on the surface of the raspberry-like microspheres which were over 160° at room temperature. PMID:26925862

  18. Raspberry-like PS/CdTe/Silica Microspheres for Fluorescent Superhydrophobic Materials

    NASA Astrophysics Data System (ADS)

    Chang, Jinghui; Zang, Linlin; Wang, Cheng; Sun, Liguo; Chang, Qing

    2016-02-01

    Superhydrophobic particulate films were fabricated via deposition of raspberry-like fluorescent PS/CdTe/silica microspheres on clean glass substrates and surface modification. Particularly, the fluorescent microspheres were prepared by a kind of modified strategy, namely introducing poly (acrylic acid)-functionalized polystyrene microspheres and thiol-stabilized CdTe quantum dots into a hydrolysis reaction of tetraethoxysilane simultaneously. And through adjusting the reaction parameters, the polystyrene spheres with two particle sizes and three colors of CdTe quantum dots aqueous solution were obtained. Consequently, raspberry-like microspheres consist of polystyrene cores and the composite shells of CdTe quantum dots and silica. These microspheres possess a fluorescent characteristic and form a hierarchical dual roughness which was conductive to superhydrophobicity, and the hydrophobic tests also showed the contact angles of water droplets on the surface of the raspberry-like microspheres which were over 160° at room temperature.

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. 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

  5. Measurement of Nanoparticle Magnetic Hyperthermia Using Fluorescent Microthermal Imaging

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaowan; van Keuren, Edward

    Nanoparticle magnetic hyperthermia uses the application of an AC magnetic field to ferromagnetic nanoparticles to elevate the temperature of cancer cells. The principle of hyperthermia as a true cell-specific therapy is that tumor cells are more sensitive to high temperature, so it is of great importance to control the locality and magnitude of the temperature differences. One technique to measure temperature variations on microscopic length scales is fluorescent microthermal imaging (FMI). Since it is the local temperature that is measured in FMI, effects such as heating due to nearby field coils can be accounted for. A dye, the rare earth chelate europium thenoyltrifluoroacetonate (Eu:TTA), with a strong temperature-dependent fluorescence emission has been incorporated into magnetic nanoparticles dispersed in a polymer films. FMI experiments were carried out on these samples under an applied high frequency magnetic field. Preliminary results show that FMI is a promising technique for characterizing the local generation of heat in nanoparticle magnetic hyperthermia.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. Fluorescent single walled nanotube/silica composite materials

    DOEpatents

    Dattelbaum, Andrew M.; Gupta, Gautam; Duque, Juan G.; Doorn, Stephen K.; Hamilton, Christopher E.; DeFriend Obrey, Kimberly A.

    2013-03-12

    Fluorescent composites of surfactant-wrapped single-walled carbon nanotubes (SWNTs) were prepared by exposing suspensions of surfactant-wrapped carbon nanotubes to tetramethylorthosilicate (TMOS) vapor. Sodium deoxycholate (DOC) and sodium dodecylsulphate (SDS) were the surfactants. No loss in emission intensity was observed when the suspension of DOC-wrapped SWNTs were exposed to the TMOS vapors, but about a 50% decrease in the emission signal was observed from the SDS-wrapped SWNTs nanotubes. The decrease in emission was minimal by buffering the SDS/SWNT suspension prior to forming the composite. Fluorescent xerogels were prepared by adding glycerol to the SWNT suspensions prior to TMOS vapor exposure, followed by drying the gels. Fluorescent aerogels were prepared by replacing water in the gels with methanol and then exposing them to supercritical fluid drying conditions. The aerogels can be used for gas sensing.

  13. Enhancing the Sensitivity of DNA Microarray Using Dye-Doped Silica Nanoparticles: Detection of Human Papilloma Virus

    NASA Astrophysics Data System (ADS)

    Enrichi, F.; Riccò, R.; Meneghello, A.; Pierobon, R.; Canton, G.; Cretaio, E.

    2010-10-01

    DNA microarray is a high-throughput technology used for detection and quantification of nucleic acid molecules and others of biological interest. The analysis is based on the specific hybridization between probe sequences deposited in array and a target ss-DNA amplified by PCR and functionalized by a fluorescent dye. Organic labels have well known disadvantages like photobleaching and low signal intensities, which put a limitation to the lower amount of DNA material that can be detected. Therefore for trace analysis the development of more efficient biomarkers is required. With this aim we present in this paper the synthesis and application of alternative hybrid nanosystems obtained by incorporating standard fluorescent molecules into monodisperse silica nanoparticles. Efficient application to the detection of Human Papilloma Virus is demonstrated. This virus is associated to the formation of cervical cancer, a leading cause of death by cancer for women worldwide. It is shown that the use of the novel biomarkers increases the optical signal of about one order of magnitude with respect to the free dyes or quantum dots in conventional instruments. This is due to the high number of molecules that can be accommodated into each nanoparticle, to the reduced photobleaching and to the improved environmental protection of the dyes when encapsulated in the silica matrix. The cheap and easy synthesis of these luminescent particles, the stability in water, the surface functionalizability and bio-compatibility make them very promising for present and future bio-labeling and bio-imaging applications.

  14. Loading of Silica Nanoparticles in Block Copolymer Vesicles during Polymerization-Induced Self-Assembly: Encapsulation Efficiency and Thermally Triggered Release

    PubMed Central

    2015-01-01

    Poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) diblock copolymer vesicles can be prepared in the form of concentrated aqueous dispersions via polymerization-induced self-assembly (PISA). In the present study, these syntheses are conducted in the presence of varying amounts of silica nanoparticles of approximately 18 nm diameter. This approach leads to encapsulation of up to hundreds of silica nanoparticles per vesicle. Silica has high electron contrast compared to the copolymer which facilitates TEM analysis, and its thermal stability enables quantification of the loading efficiency via thermogravimetric analysis. Encapsulation efficiencies can be calculated using disk centrifuge photosedimentometry, since the vesicle density increases at higher silica loadings while the mean vesicle diameter remains essentially unchanged. Small angle X-ray scattering (SAXS) is used to confirm silica encapsulation, since a structure factor is observed at q ≈ 0.25 nm–1. A new two-population model provides satisfactory data fits to the SAXS patterns and allows the mean silica volume fraction within the vesicles to be determined. Finally, the thermoresponsive nature of the diblock copolymer vesicles enables thermally triggered release of the encapsulated silica nanoparticles simply by cooling to 0–10 °C, which induces a morphological transition. These silica-loaded vesicles constitute a useful model system for understanding the encapsulation of globular proteins, enzymes, or antibodies for potential biomedical applications. They may also serve as an active payload for self-healing hydrogels or repair of biological tissue. Finally, we also encapsulate a model globular protein, bovine serum albumin, and calculate its loading efficiency using fluorescence spectroscopy. PMID:26600089

  15. Loading of Silica Nanoparticles in Block Copolymer Vesicles during Polymerization-Induced Self-Assembly: Encapsulation Efficiency and Thermally Triggered Release.

    PubMed

    Mable, Charlotte J; Gibson, Rebecca R; Prevost, Sylvain; McKenzie, Beulah E; Mykhaylyk, Oleksandr O; Armes, Steven P

    2015-12-30

    Poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) diblock copolymer vesicles can be prepared in the form of concentrated aqueous dispersions via polymerization-induced self-assembly (PISA). In the present study, these syntheses are conducted in the presence of varying amounts of silica nanoparticles of approximately 18 nm diameter. This approach leads to encapsulation of up to hundreds of silica nanoparticles per vesicle. Silica has high electron contrast compared to the copolymer which facilitates TEM analysis, and its thermal stability enables quantification of the loading efficiency via thermogravimetric analysis. Encapsulation efficiencies can be calculated using disk centrifuge photosedimentometry, since the vesicle density increases at higher silica loadings while the mean vesicle diameter remains essentially unchanged. Small angle X-ray scattering (SAXS) is used to confirm silica encapsulation, since a structure factor is observed at q ≈ 0.25 nm(-1). A new two-population model provides satisfactory data fits to the SAXS patterns and allows the mean silica volume fraction within the vesicles to be determined. Finally, the thermoresponsive nature of the diblock copolymer vesicles enables thermally triggered release of the encapsulated silica nanoparticles simply by cooling to 0-10 °C, which induces a morphological transition. These silica-loaded vesicles constitute a useful model system for understanding the encapsulation of globular proteins, enzymes, or antibodies for potential biomedical applications. They may also serve as an active payload for self-healing hydrogels or repair of biological tissue. Finally, we also encapsulate a model globular protein, bovine serum albumin, and calculate its loading efficiency using fluorescence spectroscopy. PMID:26600089

  16. Oleic acid-enhanced transdermal delivery pathways of fluorescent nanoparticles

    NASA Astrophysics Data System (ADS)

    Lo, Wen; Ghazaryan, Ara; Tso, Chien-Hsin; Hu, Po-Sheng; Chen, Wei-Liang; Kuo, Tsung-Rong; Lin, Sung-Jan; Chen, Shean-Jen; Chen, Chia-Chun; Dong, Chen-Yuan

    2012-05-01

    Transdermal delivery of nanocarriers provides an alternative pathway to transport therapeutic agents, alleviating pain, improving compliance of patients, and increasing overall effectiveness of delivery. In this work, enhancement of transdermal delivery of fluorescent nanoparticles and sulforhodamine B with assistance of oleic acid was visualized utilizing multiphoton microscopy (MPM) and analyzed quantitatively using multi-photon excitation-induced fluorescent signals. Results of MPM imaging and MPM intensity-based spatial depth-dependent analysis showed that oleic acid is effective in facilitating transdermal delivery of nanoparticles.

  17. Multispectral guided fluorescence diffuse optical tomography using upconverting nanoparticles

    SciTech Connect

    Svenmarker, Pontus; Xu, Can T.; Liu, Haichun; Wu, Xia; Andersson-Engels, Stefan

    2014-02-17

    We report on improved image detectability for fluorescence diffuse optical tomography using upconverting nanoparticles doped with rare-earth elements. Core-shell NaYF{sub 4}:Yb{sup 3+}/Er{sup 3+}@NaYF{sub 4} upconverting nanoparticles were synthesized through a stoichiometric method. The Yb{sup 3+}/Er{sup 3+} sensitizer-activator pair yielded two anti-Stokes shifted fluorescence emission bands at 540 nm and 660 nm, here used to a priori estimate the fluorescence source depth with sub-millimeter precision. A spatially varying regularization incorporated the a priori fluorescence source depth estimation into the tomography reconstruction scheme. Tissue phantom experiments showed both an improved resolution and contrast in the reconstructed images as compared to not using any a priori information.

  18. 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.

  19. 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.

  20. 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

  1. DNA-capped mesoporous silica nanoparticles as an ion-responsive release system to determine the presence of mercury in aqueous solutions

    PubMed Central

    Zhang, Yunfei; Yuan, Quan; Chen, Tao; Chen, Yan

    2013-01-01

    We have developed DNA-functionalized silica nanoparticles for the rapid, sensitive, and selective detection of mercuric ion (Hg2+) in aqueous solution. Two DNA strands were designed to cap the pore of dye-trapped silica nanoparticles. In the presence of ppb level Hg2+, the two DNA strands are dehybridized to uncap the pore, releasing the dye cargo with detectable enhancements of fluorescence signal. This method enables rapid (less than 20min) and sensitive (LOD 4ppb) detection, and it was also able to discriminate Hg2+ from twelve other environmentally relevant metal ions. The superior properties of the as-designed DNA-functionalized silica nanoparticles can be attributed to the large loading capacity and highly ordered pore structure of mesoporous silica nanoparticles, as well as the selective binding of thymine-rich DNA with Hg2+ . Our design serves as a new prototype for metal-ion sensing systems and it also has promising potential for detection of various targets in stimulus-release systems. PMID:22240146

  2. 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.

  3. Intrinsic fluorescence of selenium nanoparticles for cellular imaging applications

    NASA Astrophysics Data System (ADS)

    Khalid, A.; Tran, Phong A.; Norello, Romina; Simpson, David A.; O'Connor, Andrea J.; Tomljenovic-Hanic, Snjezana

    2016-02-01

    Nanoparticles hold great potential in contributing to high-resolution bioimaging as well as for biomedical applications. Although, selenium (Se) nanoparticles (NPs) have been investigated owing to their potential roles in therapeutics, the imaging capability of these NPs has never been explored. This manuscript identifies the intrinsic fluorescence of Se NPs, which is highly beneficial for nanoscale imaging of biological structures. The emission of individual NPs and its evolution with time is explored. The photoluminescence spectra has revealed visible to near infrared emission for Se NPs. The work finally reflects on the role of this intrinsic fluorescence for in vitro imaging and tracking in fibroblast cells, without the need of any additional tags. This technique would overcome the limitations of the conventionally used methods of imaging with tagged fluorescent proteins and dyes, preventing possible adverse cellular effects or phototoxicity caused by the added fluorescent moieties.Nanoparticles hold great potential in contributing to high-resolution bioimaging as well as for biomedical applications. Although, selenium (Se) nanoparticles (NPs) have been investigated owing to their potential roles in therapeutics, the imaging capability of these NPs has never been explored. This manuscript identifies the intrinsic fluorescence of Se NPs, which is highly beneficial for nanoscale imaging of biological structures. The emission of individual NPs and its evolution with time is explored. The photoluminescence spectra has revealed visible to near infrared emission for Se NPs. The work finally reflects on the role of this intrinsic fluorescence for in vitro imaging and tracking in fibroblast cells, without the need of any additional tags. This technique would overcome the limitations of the conventionally used methods of imaging with tagged fluorescent proteins and dyes, preventing possible adverse cellular effects or phototoxicity caused by the added fluorescent

  4. 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

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Precise diagnosis in different scenarios using photoacoustic and fluorescence imaging with dual-modality nanoparticles

    NASA Astrophysics Data System (ADS)

    Peng, Dong; Du, Yang; Shi, Yiwen; Mao, Duo; Jia, Xiaohua; Li, Hui; Zhu, Yukun; Wang, Kun; Tian, Jie

    2016-07-01

    Photoacoustic imaging and fluorescence molecular imaging are emerging as important research tools for biomedical studies. Photoacoustic imaging offers both strong optical absorption contrast and high ultrasonic resolution, and fluorescence molecular imaging provides excellent superficial resolution, high sensitivity, high throughput, and the ability for real-time imaging. Therefore, combining the imaging information of both modalities can provide comprehensive in vivo physiological and pathological information. However, currently there are limited probes available that can realize both fluorescence and photoacoustic imaging, and advanced biomedical applications for applying this dual-modality imaging approach remain underexplored. In this study, we developed a dual-modality photoacoustic-fluorescence imaging nanoprobe, ICG-loaded Au@SiO2, which was uniquely designed, consisting of gold nanorod cores and indocyanine green with silica shell spacer layers to overcome fluorophore quenching. This nanoprobe was examined by both PAI and FMI for in vivo imaging on tumor and ischemia mouse models. Our results demonstrated that the nanoparticles can specifically accumulate at the tumor and ischemic areas and be detected by both imaging modalities. Moreover, this dual-modality imaging strategy exhibited superior advantages for a precise diagnosis in different scenarios. The new nanoprobe with the dual-modality imaging approach holds great potential for diagnosis and stage classification of tumor and ischemia related diseases.Photoacoustic imaging and fluorescence molecular imaging are emerging as important research tools for biomedical studies. Photoacoustic imaging offers both strong optical absorption contrast and high ultrasonic resolution, and fluorescence molecular imaging provides excellent superficial resolution, high sensitivity, high throughput, and the ability for real-time imaging. Therefore, combining the imaging information of both modalities can provide

  15. Functional ionic liquids induced the formation of mitochondria targeted fluorescent core-shell ellipsoidal nanoparticles with anticancer properties.

    PubMed

    Yang, Xia; Chen, Qiu-Yun; Li, Xiang; Gao, Jing

    2012-10-01

    A functional ionic liquid (IL) (IL=4-acetyl-N-butyl pyridinium hexafluorophosphate) was synthesized and conjugated with low toxicity of nanospheres (RBITC@SiO(2)), forming a new kind of fluorescent core-shell ellipsoidal RBITC@SiO(2)-IL nanoparticle. In vitro assay results indicate that particle shape plays an important role in cellular interactions with NPs. Furthermore, the positively charged ellipsoidal RBITC@SiO(2)-IL nanoparticles can enter into HeLa cells and induce the cells to condense, split and decrease on the oxygen consumption. The enhanced cell image and decrease of mitochondria potential indicate that the ellipsoidal RBITC@SiO(2)-IL nanoparticles could be uptaken by HeLa cells through mitochondria involved path. Experimental results give us a new path to design nano-medicines through ionic liquid modified silica nanoparticles to target mitochondria. PMID:22659209

  16. Targeted delivery of doxorubicin to mitochondria using mesoporous silica nanoparticle nanocarriers

    NASA Astrophysics Data System (ADS)

    Qu, Qiuyu; Ma, Xing; Zhao, Yanli

    2015-10-01

    A lot of investigations have been conducted using mesoporous silica nanoparticles (MSNPs) functionalized with different targeting ligands in order to deliver various hydrophobic and hydrophilic drugs to targeted cancer cells. However, the utilization of MSNPs to deliver drug molecules to targeted subcellular organelles has been rarely reported. In this work, we applied targeting ligand-conjugated MSNPs with an average diameter of 80 nm to deliver the anticancer drug doxorubicin (DOX) to mitochondria. Triphenoylphosphonium (TPP) was functionalized on MSNPs as a mitochondria targeting ligand. Mitochondria targeting efficiency was demonstrated in HeLa cells by a co-localization study of mitochondria and functionalized MSNPs as well as by fluorescence analysis in isolated mitochondria. In addition, enhanced cancer cell killing efficacy was achieved when using DOX-loaded and TPP-functionalized MSNPs for mitochondria-targeted delivery. Lowered adenosine triphosphate (ATP) production and decreased mitochondrial membrane potential were observed, demonstrating the mitochondria dysfunction caused by delivered DOX. The positive results indicate promising application potential of MSNPs in targeted subcellular drug delivery.A lot of investigations have been conducted using mesoporous silica nanoparticles (MSNPs) functionalized with different targeting ligands in order to deliver various hydrophobic and hydrophilic drugs to targeted cancer cells. However, the utilization of MSNPs to deliver drug molecules to targeted subcellular organelles has been rarely reported. In this work, we applied targeting ligand-conjugated MSNPs with an average diameter of 80 nm to deliver the anticancer drug doxorubicin (DOX) to mitochondria. Triphenoylphosphonium (TPP) was functionalized on MSNPs as a mitochondria targeting ligand. Mitochondria targeting efficiency was demonstrated in HeLa cells by a co-localization study of mitochondria and functionalized MSNPs as well as by fluorescence analysis

  17. 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

  18. Mesoporous silica nanoparticles as a breast cancer targeting contrast agent for ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Milgroom, Andrew Carson

    Current clinical use of ultrasound for breast cancer diagnostics is strictly limited to a role as a supplementary detection method to other modalities, such as mammography or MRI. A major reason for ultrasound’s role as a secondary method is its inability to discern between cancerous and non-cancerous bodies of similar density, like dense calcifications or benign fibroadenomas. Its detection capabilities are further diminished by the variable density of the surrounding breast tissue with the progression of age. Preliminary studies suggest that mesoporous silica nanoparticles (MSNs) are a good candidate as an in situ contrast agent for ultrasound. By tagging the silica particle surface with the cancer-targeting antibody trastuzumab (Herceptin), suspect regions of interest can be better identified in real time with standard ultrasound equipment. Once the silica-antibody conjugate is injected into the bloodstream and enters the cancerous growth’s vasculature, the antibody arm will bind to HER2, a cell surface receptor known to be dysfunctional or overexpressed in certain types of breast cancer. As more particles aggregate at the cell surface, backscatter of the ultrasonic waves increases as a result of the higher porous silica concentration. This translates to an increased contrast around the lesion boundary. Tumor detection through ultrasound contrast enhancement provides a tremendous advantage over current cancer diagnostics because is it significantly cheaper and can be monitored in real time. Characterization of MCM-41 type MSNs suggests that these particles have sufficient stability and particle size distribution to penetrate through fenestrated tumor vasculature and accumulate in HER2+ breast cancer cells through the enhanced permeation and retention (EPR) effect. A study of acoustic properties showed that particle concentration is linearly correlated to image contrast in clinical frequency-range ultrasound, although less pronounced than typical microbubble

  19. Dual-Labeled Near-Infrared/99mTc Imaging Probes Using PAMAM-Coated Silica Nanoparticles for the Imaging of HER2-Expressing Cancer Cells

    PubMed Central

    Yamaguchi, Haruka; Tsuchimochi, Makoto; Hayama, Kazuhide; Kawase, Tomoyuki; Tsubokawa, Norio

    2016-01-01

    We sought to develop dual-modality imaging probes using functionalized silica nanoparticles to target human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer cells and achieve efficient target imaging of HER2-expressing tumors. Polyamidoamine-based functionalized silica nanoparticles (PCSNs) for multimodal imaging were synthesized with near-infrared (NIR) fluorescence (indocyanine green (ICG)) and technetium-99m (99mTc) radioactivity. Anti-HER2 antibodies were bound to the labeled PCSNs. These dual-imaging probes were tested to image HER2-overexpressing breast carcinoma cells. In vivo imaging was also examined in breast tumor xenograft models in mice. SK-BR3 (HER2 positive) cells were imaged with stronger NIR fluorescent signals than that in MDA-MB231 (HER2 negative) cells. The increased radioactivity of the SK-BR3 cells was also confirmed by phosphor imaging. NIR images showed strong fluorescent signals in the SK-BR3 tumor model compared to muscle tissues and the MDA-MB231 tumor model. Automatic well counting results showed increased radioactivity in the SK-BR3 xenograft tumors. We developed functionalized silica nanoparticles loaded with 99mTc and ICG for the targeting and imaging of HER2-expressing cells. The dual-imaging probes efficiently imaged HER2-overexpressing cells. Although further studies are needed to produce efficient isotope labeling, the results suggest that the multifunctional silica nanoparticles are a promising vehicle for imaging specific components of the cell membrane in a dual-modality manner. PMID:27399687

  20. Dual-Labeled Near-Infrared/(99m)Tc Imaging Probes Using PAMAM-Coated Silica Nanoparticles for the Imaging of HER2-Expressing Cancer Cells.

    PubMed

    Yamaguchi, Haruka; Tsuchimochi, Makoto; Hayama, Kazuhide; Kawase, Tomoyuki; Tsubokawa, Norio

    2016-01-01

    We sought to develop dual-modality imaging probes using functionalized silica nanoparticles to target human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer cells and achieve efficient target imaging of HER2-expressing tumors. Polyamidoamine-based functionalized silica nanoparticles (PCSNs) for multimodal imaging were synthesized with near-infrared (NIR) fluorescence (indocyanine green (ICG)) and technetium-99m ((99m)Tc) radioactivity. Anti-HER2 antibodies were bound to the labeled PCSNs. These dual-imaging probes were tested to image HER2-overexpressing breast carcinoma cells. In vivo imaging was also examined in breast tumor xenograft models in mice. SK-BR3 (HER2 positive) cells were imaged with stronger NIR fluorescent signals than that in MDA-MB231 (HER2 negative) cells. The increased radioactivity of the SK-BR3 cells was also confirmed by phosphor imaging. NIR images showed strong fluorescent signals in the SK-BR3 tumor model compared to muscle tissues and the MDA-MB231 tumor model. Automatic well counting results showed increased radioactivity in the SK-BR3 xenograft tumors. We developed functionalized silica nanoparticles loaded with (99m)Tc and ICG for the targeting and imaging of HER2-expressing cells. The dual-imaging probes efficiently imaged HER2-overexpressing cells. Although further studies are needed to produce efficient isotope labeling, the results suggest that the multifunctional silica nanoparticles are a promising vehicle for imaging specific components of the cell membrane in a dual-modality manner. PMID:27399687

  1. 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.

  2. 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.

  3. 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.

  4. Maximizing dye fluorescence via incorporation of metallic nanoparticles in solution

    NASA Astrophysics Data System (ADS)

    Xu, Yang; Lei, Guangyin; Booker, Annette C.; Linares, Katherine A.; Fleming, Dara L.; Meehan, Kathleen; Lu, Guo-Quan; Love, Nancy G.; Love, Brian J.

    2004-12-01

    Gram-negative bacteria initiate a stress response in which the cells efflux potassium when electrophilic toxins are introduced into their environment. Hence, measurement of K+ concentration in the surrounding water using a fluorescence-based potassium-selective optode has been proposed for environmental and homeland security applications. Unfortunately, the fluorophore commonly used in such an optode is inefficient. Surface enhanced fluorescence (SEF) can be used to increase its fluorescence efficiency, which will improve the sensor's performance. To understand this phenomenon before applying it to the optode system, Rose Bengal (RB), an inexpensive and well characterized dye, in solution with gold and silver nanoparticles was studied. As expected, fluorescence from RB-gold solutions was low since alignment of gold's surface plasmon resonance (SPR) peak and absorption and fluorescence energies in RB favored energy transfer from RB to the gold nanoparticles. The alignment of the silver's SPR peak and the RB transitions favored transfer from silver to RB. SEF was observed in solutions with large dye-to-silver separation. However, little fluorescence was observed when the solution was pumped at the silver's SPR peak. Fluorescence from the dye decreased as dye-to-silver separation decreased. An explanation for these observations is presented; additional research is needed to develop a complete understanding.

  5. Novel copper (Cu) loaded core-shell silica nanoparticles with improved Cu bioavailability: synthesis, characterization and study of antibacterial properties.

    PubMed

    Maniprasad, Pavithra; Santra, Swadeshmukul

    2012-08-01

    We report synthesis of a novel core-shell silica based antimicrobial nanoparticles where the silica shell has been engineered to accommodate copper (Cu). Synthesis of the core-shell Cu-silica nanoparticle (C-S CuSiO2NP) involves preparation of base-hydrolyzed Stöber silica "seed" particles first, followed by the acid-catalyzed seeded growth of the Cu-silica shell layer around the core. The Scanning Electron Microscopy (SEM) and the Transmission Electron Microscopy (TEM) measured the seed particle size to be -380 nm and the shell thickness to be -35 nm. The SEM particle characterization confirms formation of highly monodispersed particles with smooth surface morphology. Characterization of particle size distribution in solution by Dynamic Light Scattering (DLS) technique was fairly consistent with the electron microscopy results. Loading of Cu to nanoparticles was confirmed by the SEM-Energy Dispersive X-Ray Spectroscopy (EDS) and Atomic Absorption Spectroscopy (AAS). The Cu loading was estimated to be 0.098 microg of metallic copper per mg of C-S CuSiO2NP material by the AAS technique. Antibacterial efficacy of C-S CuSiO2NP was evaluated against E. coli and B. subtilis using Cu hydroxide ("Insoluble" Cu compound, sub-micron size particles) as positive control and silica "seed" particles (without Cu loading) as negative control. Bacterial growth in solution was measured against different concentrations of C-S CuSiO2NP to determine the Minimum Inhibitory Concentration (MIC) value. The estimated MIC values were 2.4 microg metallic Cu/mL for both E. coli and B. subtilis. Bac-light fluorescence microscopy based assay was used to count relative population of the live and dead bacteria cells. Antibacterial study clearly shows that C-S CuSiO2NP is more effective than insoluble Cu hydroxide particles at equivalent metallic Cu concentration, suggesting improvement of Cu bioavailability (i.e., more soluble Cu) in C-SCuSiO2NP material due to its core-shell design. PMID

  6. 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

  7. 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

  8. 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

  9. Multifunctional polymer-capped mesoporous silica nanoparticles for pH-responsive targeted drug delivery

    NASA Astrophysics Data System (ADS)

    Niedermayer, Stefan; Weiss, Veronika; Herrmann, Annika; Schmidt, Alexandra; Datz, Stefan; Müller, Katharina; Wagner, Ernst; Bein, Thomas; Bräuchle, Christoph

    2015-04-01

    A highly stable modular platform, based on the sequential covalent attachment of different functionalities to the surface of core-shell mesoporous silica nanoparticles (MSNs) for targeted drug delivery is presented. A reversible pH-responsive cap system based on covalently attached poly(2-vinylpyridine) (PVP) was developed as drug release mechanism. Our platform offers (i) tuneable interactions and release kinetics with the cargo drug in the mesopores based on chemically orthogonal core-shell design, (ii) an extremely robust and reversible closure and release mechanism based on endosomal acidification of the covalently attached PVP polymer block, (iii) high colloidal stability due to a covalently coupled PEG shell, and (iv) the ability to covalently attach a wide variety of dyes, targeting ligands and other functionalities at the outer periphery of the PEG shell. The functionality of the system was demonstrated in several cell studies, showing pH-triggered release in the endosome, light-triggered endosomal escape with an on-board photosensitizer, and efficient folic acid-based cell targeting.A highly stable modular platform, based on the sequential covalent attachment of different functionalities to the surface of core-shell mesoporous silica nanoparticles (MSNs) for targeted drug delivery is presented. A reversible pH-responsive cap system based on covalently attached poly(2-vinylpyridine) (PVP) was developed as drug release mechanism. Our platform offers (i) tuneable interactions and release kinetics with the cargo drug in the mesopores based on chemically orthogonal core-shell design, (ii) an extremely robust and reversible closure and release mechanism based on endosomal acidification of the covalently attached PVP polymer block, (iii) high colloidal stability due to a covalently coupled PEG shell, and (iv) the ability to covalently attach a wide variety of dyes, targeting ligands and other functionalities at the outer periphery of the PEG shell. The

  10. 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

  11. Trastuzumab-Conjugated Liposome-Coated Fluorescent Magnetic Nanoparticles to Target Breast Cancer

    PubMed Central

    Jang, Mijung; Yoon, Young Il; Kwon, Yong Soo; Yoon, Tae-Jong; Lee, Hak Jong; Hwang, Sung Il; Yun, Bo La

    2014-01-01

    Objective To synthesize mesoporous silica-core-shell magnetic nanoparticles (MNPs) encapsulated by liposomes (Lipo [MNP@m-SiO2]) in order to enhance their stability, allow them to be used in any buffer solution, and to produce trastuzumab-conjugated (Lipo[MNP@m-SiO2]-Her2Ab) nanoparticles to be utilized in vitro for the targeting of breast cancer. Materials and Methods The physiochemical characteristics of Lipo[MNP@m-SiO2] were assessed in terms of size, morphological features, and in vitro safety. The multimodal imaging properties of the organic dye incorporated into Lipo[MNP@m-SiO2] were assessed with both in vitro fluorescence and MR imaging. The specific targeting ability of trastuzumab (Her2/neu antibody, Herceptin®)-conjugated Lipo[MNP@m-SiO2] for Her2/neu-positive breast cancer cells was also evaluated with fluorescence and MR imaging. Results We obtained uniformly-sized and evenly distributed Lipo[MNP@m-SiO2] that demonstrated biological stability, while not disrupting cell viability. Her2/neu-positive breast cancer cell targeting by trastuzumab-conjugated Lipo[MNP@m-SiO2] was observed by in vitro fluorescence and MR imaging. Conclusion Trastuzumab-conjugated Lipo[MNP@m-SiO2] is a potential treatment tool for targeted drug delivery in Her2/neu-positive breast cancer. PMID:25053899

  12. 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.

  13. Spectral dependence of fluorescence near plasmon resonant metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Yeechi

    The optical properties of fluorophores are significantly modified when placed within the near field (0--100 nm) of plasmon resonant metal nanostructures, due to the competition between increased decay rates and "hotspots" of concentrated electric fields. The decay rates and effective electric field intensities are highly dependent on the relative position of dye and metal and the overlap between plasmon resonance and dye absorption and emission. Understanding these dependencies can greatly improve the performance of biosensing and nanophotonic devices. In this dissertation, the fluorescence intensity of organic dyes and CdSe quantum dots near single metal nanoparticles is studied as a function of the local surface plasmon resonance (LSPR) of the nanoparticle. Single metal nanoparticles have narrow, well-defined, intense local surface plasmon resonances that are tunable across the visible spectrum by changes in size and shape. First, we show that organic dyes can be self-assembled on single silver nanoprisms into known configurations by the hybridization of thiolated DNA oligomers. We correlate the fluorescence intensity of the dyes to the LSPR of the individual nanoprism to which they are attached. For each of three different organic dyes, we observe a strong correlation between the fluorescence intensity of the dye and the degree of spectral overlap with the plasmon resonance of the nanoparticle. On average, we observe the brightest fluorescence from dyes attached to metal nanoparticles that have a LSPR scattering peak 40--120 meV higher in energy than the emission peak of the fluorophore. Second, the plasmon-enhanced fluorescence from CdSe/CdS/CdZnS/ZnS core/shell quantum dots is studied near a variety of silver and gold nanoparticles. With single-particle scattering spectroscopy, the localized surface plasmon resonance spectra of single metal nanoparticles is correlated with the photoluminescence excitation (PLE) spectra of the nearby quantum dots. The PLE

  14. Magnetite nanoparticles for biosensor model based on bacteria fluorescence

    NASA Astrophysics Data System (ADS)

    Poita, A.; Creanga, D.-E.; Airinei, A.; Tupu, P.; Goiceanu, C.; Avadanei, O.

    2009-06-01

    Fluorescence emission of pyoverdine - the siderophore synthesized by iron scavenger bacteria - was studied using in vitro cultures of Pseudomonas aeruginosa with the aim to design a biosensor system for liquid sample iron loading. Diluted suspensions of colloidal magnetite nanoparticles were supplied in the culture medium (10 microl/l and 100 microl/l) to simulate magnetic loading with iron oxides of either environmental waters or human body fluids. The electromagnetic exposure to radiofrequency waves of bacterial samples grown in the presence of magnetic nanoparticles was also carried out. Cell density diminution but fluorescence stimulation following 10 microl/l ferrofluid addition and simultaneous exposure to radiofrequency waves was evidenced. The inhibitory influence of 100 microl/l ferrofluid combined with RF exposure was evidenced by fluorescence data. Mathematical model was proposed to approach quantitatively the dynamics of cell density and fluorescence emission in relation with the consumption of magnetite nanoparticle supplied medium. The biosensor scheme was shaped based on the response to iron loading of bacterial sample fluorescence.

  15. Ligand Assisted Stabilization of Fluorescence Nanoparticles; an Insight on the Fluorescence Characteristics, Dispersion Stability and DNA Loading Efficiency of Nanoparticles.

    PubMed

    Rhouati, Amina; Hayat, Akhtar; Mishra, Rupesh K; Bueno, Diana; Shahid, Shakir Ahmad; Muñoz, Roberto; Marty, Jean Louis

    2016-07-01

    This work reports on the ligand assisted stabilization of Fluospheres® carboxylate modified nanoparticles (FCMNPs), and subsequently investigation on the DNA loading capacity and fluorescence response of the modified particles. The designed fluorescence bioconjugate was characterized with enhanced fluorescence characteristics, good stability and large surface area with high DNA loading efficiency. For comparison purpose, bovine serum albumin (BSA) and polyethylene glycol (PEG) with three different length strands were used as cross linkers to modify the particles, and their DNA loading capacity and fluorescence characteristics were investigated. By comparing the performance of the particles, we found that the most improved fluorescence characteristics, enhanced DNA loading and high dispersion stability were obtained, when employing PEG of long spacer arm length. The designed fluorescence bioconjugate was observed to maintain all its characteristics under varying pH over an extended period of time. These types of bioconjugates are in great demand for fluorescence imaging and in vivo fluorescence biomedical application, especially when most of the as synthesized fluorescence particles cannot withstand to varying in vivo physiological conditions with decreases in fluorescence response and DNA loading efficiency. PMID:27209005

  16. 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

  17. 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.

  18. Proper design of silica nanoparticles combines high brightness, lack of cytotoxicity and efficient cell endocytosis

    NASA Astrophysics Data System (ADS)

    Rampazzo, Enrico; Voltan, Rebecca; Petrizza, Luca; Zaccheroni, Nelsi; Prodi, Luca; Casciano, Fabio; Zauli, Giorgio; Secchiero, Paola

    2013-08-01

    Silica-based luminescent nanoparticles (SiNPs) show promising prospects in nanomedicine in light of their chemical properties and versatility. In this study, we have characterized silica core-PEG shell SiNPs derivatized with PEG moieties (NP-PEG), with external amino- (NP-PEG-amino) or carboxy-groups (NP-PEG-carbo), both in cell cultures as well as in animal models. By using different techniques, we could demonstrate that these SiNPs were safe and did not exhibit appreciable cytotoxicity in different relevant cell models, of normal or cancer cell types, growing either in suspension (JVM-2 leukemic cell line and primary normal peripheral blood mononuclear cells) or in adherence (human hepatocarcinoma Huh7 and umbilical vein endothelial cells). Moreover, by multiparametric flow cytometry, we could demonstrate that the highest efficiency of cell uptake and entry was observed with NP-PEG-amino, with a stable persistence of the fluorescence signal associated with SiNPs in the loaded cell populations both in vitro and in vivo settings suggesting this as an innovative method for cell traceability and detection in whole organisms. Finally, experiments performed with the endocytosis inhibitor Genistein clearly suggested the involvement of a caveolae-mediated pathway in SiNP endocytosis. Overall, these data support the safe use of these SiNPs for diagnostic and therapeutic applications.Silica-based luminescent nanoparticles (SiNPs) show promising prospects in nanomedicine in light of their chemical properties and versatility. In this study, we have characterized silica core-PEG shell SiNPs derivatized with PEG moieties (NP-PEG), with external amino- (NP-PEG-amino) or carboxy-groups (NP-PEG-carbo), both in cell cultures as well as in animal models. By using different techniques, we could demonstrate that these SiNPs were safe and did not exhibit appreciable cytotoxicity in different relevant cell models, of normal or cancer cell types, growing either in suspension (JVM-2

  19. 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.

  20. 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

  1. Silica encapsulation of fluorescent nanodiamonds for colloidal stability and facile surface functionalization

    PubMed Central

    Bumb, Ambika; Sarkar, Susanta K.; Billington, Neil; Brechbiel, Martin W.; Neuman, Keir C.

    2013-01-01

    Fluorescent nanodiamonds (FNDs) emit in the near infrared and do not photo-bleach or photoblink. These properties make FNDs better suited for numerous imaging applications in comparison to commonly used fluorescence agents such as organic dyes and quantum dots. However, nanodiamonds do not form stable suspensions in aqueous buffer, are prone to aggregation, and are difficult to functionalize. Here, we present a method to encapsulate nanodiamonds with silica using an innovative liposome-based encapsulation process that renders the particle surface biocompatible, stable, and readily functionalized through routine linking chemistries. Furthermore, the method selects for a desired particle size and produces a monodisperse agent. We attached biotin to the silica-coated FNDs and tracked the three-dimensional motion of a biotinylated FND tethered by a single DNA molecule with high spatial and temporal resolution. PMID:23581827

  2. Horseradish peroxidase-immobilized magnetic mesoporous silica nanoparticles as a potential candidate to eliminate intracellular reactive oxygen species.

    PubMed

    Shen, Yajing; Zhang, Ye; Zhang, Xiang; Zhou, Xiuhong; Teng, Xiyao; Yan, Manqing; Bi, Hong

    2015-02-21

    Horseradish peroxidase-immobilized magnetic mesoporous silica nanoparticles (MMSNs-HRP) have been synthesized by a NHS/EDC coupling between the amino groups of horseradish peroxidase (HRP) and the carboxyl groups on the MMSNs surface. It is found that the immobilized HRP on MMSNs still retain high activity and the MMSNs-HRP can eliminate the reactive oxygen species (ROS) in Chinese hamster ovary (CHO) cells induced by the addition of H2O2 aqueous solution. Further, the fluorescent MMSN-HRP-CD nanoparticles have been prepared by attaching biocompatible, fluorescent carbon dots (CDs) to MMSNs-HRP. We have also investigated the effect of an applied magnetic field on cellular uptake of MMSNs-HRP-CDs and found that the internalization of MMSNs-HRP-CDs by CHO cells could be enhanced within 2 hours under the magnetic field. This work provides us with a novel and efficient method to eliminate ROS in living cells by using HRP-immobilized nanoparticles. PMID:25587910

  3. Facile Synthesis of Gold Nanospheres Modified by Positively Charged Mesoporous Silica, Loaded with Near-Infrared Fluorescent Dye, for in Vivo X-ray Computed Tomography and Fluorescence Dual Mode Imaging.

    PubMed

    Song, Ji-Tao; Yang, Xiao-Quan; Zhang, Xiao-Shuai; Yan, Dong-Mei; Wang, Zhao-Yang; Zhao, Yuan-Di

    2015-08-12

    We developed a simple and efficient method to synthesize a novel probe for both computed tomography (CT) and fluorescence imaging. Gold nanospheres were coated with positively charged mesoporous silica (Au@mSiO2-TTA) using a one-pot method to cohydrolyze quaternary ammonium silane and tetraethyl orthosilicate. Subsequently, IR-783, a negatively charged and water-soluble near-infrared fluorescent dye, was electrostatically adsorbed into the silica shell. Transmission electron microscopy imaging, X-ray powder diffraction, and energy dispersive X-ray spectroscopy indicated that Au@mSiO2-TTA had a clear core-shell structure, was monodisperse, had a large surface area (530 m2/g), and had a uniform pore size (2.2 nm). The mesoporous structure could effectively load fluorescent dye. After loading, the zeta potential of the nanoparticle dropped from 48 mV to 30 mV, and after additional modification with polyvinylpyrrolidone, it further reduced to 6 mV. Probe fluorescence was stable over time, and the probe was an effective CT contrast agent and as a near-infrared fluorescent probe. The half-life of the probe in the blood was 1.5 h, and the probe was mainly distributed in the spleen and liver 4 h after injection. Tissue sections showed that major organs were normal and without visible morphological changes, 6 days post injection, indicating the biocompatibility of the probe. PMID:26189815

  4. Immobilization of fluorescent chemosensor on pyrogenic silica: a promising device for gaseous detection.

    PubMed

    Becuwe, M; Danjou, P-E; Cazier, F; Woisel, P; Delattre, F

    2015-07-15

    A new approach to enhance performances of a cyclodextrin-based fluorescent chemosensor combining grafting on a silica matrix and quaternization reaction is presented. The full characterization of new fluorescent hybrid material has clearly revealed the embedding of cyclodextrin inside the siliceous material. Finally, through a comparison with previous aqueous studies, a preliminary test of toluene detection was presented and highlighted the high potential of this approach, which opens attractive perspectives of evolution toward more sensitive and selective VOC's sensing in air or in hot industrial gaseous waste. PMID:25801133

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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

  16. Detection of cancerous cervical cells using physical adhesion of fluorescent silica particles and centripetal force.

    PubMed

    Gaikwad, Ravi M; Dokukin, Maxim E; Iyer, K Swaminathan; Woodworth, Craig D; Volkov, Dmytro O; Sokolov, Igor

    2011-04-01

    Here we describe a non-traditional method to identify cancerous human cervical epithelial cells in a culture dish based on physical adhesion between silica beads and cells. It is a simple optical fluorescence-based technique which detects the relative difference in the amount of fluorescent silica beads physically adherent to surfaces of cancerous and normal cervical cells. The method utilizes the centripetal force gradient that occurs in a rotating culture dish. Due to the variation in the balance between adhesion and centripetal forces, cancerous and normal cells demonstrate clearly distinctive distributions of the fluorescent particles adherent to the cell surface over the culture dish. The method demonstrates higher adhesion of silica particles to normal cells compared to cancerous cells. The difference in adhesion was initially observed by atomic force microscopy (AFM). The AFM data were used to design the parameters of the rotational dish experiment. The optical method that we describe is much faster and technically simpler than AFM. This work provides proof of the concept that physical interactions can be used to accurately discriminate normal and cancer cells. PMID:21305062

  17. Detection of cancerous cervical cells using physical adhesion of fluorescent silica particles and centripetal force

    PubMed Central

    Gaikwad, Ravi M.; Dokukin, Maxim E.; Iyer, K. Swaminathan; Woodworth, Craig D.; Volkov, Dmytro O.; Sokolov, Igor

    2012-01-01

    Here we describe a non-traditional method to identify cancerous human cervical epithelial cells in a culture dish based on physical interaction between silica beads and cells. It is a simple optical fluorescence-based technique which detects the relative difference in the amount of fluorescent silica beads physically adherent to surfaces of cancerous and normal cervical cells. The method utilizes the centripetal force gradient that occurs in a rotating culture dish. Due to the variation in the balance between adhesion and centripetal forces, cancerous and normal cells demonstrate clearly distinctive distributions of the fluorescent particles adherent to the cell surface over the culture dish. The method demonstrates higher adhesion of silica particles to normal cells compared to cancerous cells. The difference in adhesion was initially observed by atomic force microscopy (AFM). The AFM data were used to design the parameters of the rotational dish experiment. The optical method that we describe is much faster and technically simpler than AFM. This work provides proof of the concept that physical interactions can be used to accurately discriminate normal and cancer cells. PMID:21305062

  18. 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

  19. 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

  20. 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.

  1. Engineering of hollow mesoporous silica nanoparticles for remarkably enhanced tumor active targeting efficacy.

    PubMed

    Chen, Feng; Hong, Hao; Shi, Sixiang; Goel, Shreya; Valdovinos, Hector F; Hernandez, Reinier; Theuer, Charles P; Barnhart, Todd E; Cai, Weibo

    2014-01-01

    Hollow mesoporous silica nanoparticle (HMSN) has recently gained increasing interests due to their tremendous potential as an attractive nano-platform for cancer imaging and therapy. However, possibly due to the lack of efficient in vivo targeting strategy and well-developed surface engineering techniques, engineering of HMSN for in vivo active tumor targeting, quantitative tumor uptake assessment, multimodality imaging, biodistribution and enhanced drug delivery have not been achieved to date. Here, we report the in vivo tumor targeted positron emission tomography (PET)/near-infrared fluorescence (NIRF) dual-modality imaging and enhanced drug delivery of HMSN using a generally applicable surface engineering technique. Systematic in vitro and in vivo studies have been performed to investigate the stability, tumor targeting efficacy and specificity, biodistribution and drug delivery capability of well-functionalized HMSN nano-conjugates. The highest uptake of TRC105 (which binds to CD105 on tumor neovasculature) conjugated HMSN in the 4T1 murine breast cancer model was ~10%ID/g, 3 times higher than that of the non-targeted group, making surface engineered HMSN a highly attractive drug delivery nano-platform for future cancer theranostics. PMID:24875656

  2. Engineering of Hollow Mesoporous Silica Nanoparticles for Remarkably Enhanced Tumor Active Targeting Efficacy

    PubMed Central

    Chen, Feng; Hong, Hao; Shi, Sixiang; Goel, Shreya; Valdovinos, Hector F.; Hernandez, Reinier; Theuer, Charles P.; Barnhart, Todd E.; Cai, Weibo

    2014-01-01

    Hollow mesoporous silica nanoparticle (HMSN) has recently gained increasing interests due to their tremendous potential as an attractive nano-platform for cancer imaging and therapy. However, possibly due to the lack of efficient in vivo targeting strategy and well-developed surface engineering techniques, engineering of HMSN for in vivo active tumor targeting, quantitative tumor uptake assessment, multimodality imaging, biodistribution and enhanced drug delivery have not been achieved to date. Here, we report the in vivo tumor targeted positron emission tomography (PET)/near-infrared fluorescence (NIRF) dual-modality imaging and enhanced drug delivery of HMSN using a generally applicable surface engineering technique. Systematic in vitro and in vivo studies have been performed to investigate the stability, tumor targeting efficacy and specificity, biodistribution and drug delivery capability of well-functionalized HMSN nano-conjugates. The highest uptake of TRC105 (which binds to CD105 on tumor neovasculature) conjugated HMSN in the 4T1 murine breast cancer model was ~10%ID/g, 3 times higher than that of the non-targeted group, making surface engineered HMSN a highly attractive drug delivery nano-platform for future cancer theranostics. PMID:24875656

  3. Silica Nanoparticles Induce Oxidative Stress and Autophagy but Not Apoptosis in the MRC-5 Cell Line

    PubMed Central

    Petrache Voicu, Sorina Nicoleta; Dinu, Diana; Sima, Cornelia; Hermenean, Anca; Ardelean, Aurel; Codrici, Elena; Stan, Miruna Silvia; Zărnescu, Otilia; Dinischiotu, Anca

    2015-01-01

    This study evaluated the in vitro effects of 62.5 µg/mL silica nanoparticles (SiO2 NPs) on MRC-5 human lung fibroblast cells for 24, 48 and 72 h. The nanoparticles’ morphology, composition, and structure were investigated using high resolution transmission electron microscopy, selected area electron diffraction and X-ray diffraction. Our study showed a decreased cell viability and the induction of cellular oxidative stress as evidenced by an increased level of reactive oxygen species (ROS), carbonyl groups, and advanced oxidation protein products after 24, 48, and 72 h, as well as a decreased concentration of glutathione (GSH) and protein sulfhydryl groups. The protein expression of Hsp27, Hsp60, and Hsp90 decreased at all time intervals, while the level of protein Hsp70 remained unchanged during the exposure. Similarly, the expression of p53, MDM2 and Bcl-2 was significantly decreased for all time intervals, while the expression of Bax, a marker for apoptosis, was insignificantly downregulated. These results correlated with the increase of pro-caspase 3 expression. The role of autophagy in cellular response to SiO2 NPs was demonstrated by a fluorescence-labeled method and by an increased level of LC3-II/LC3-I ratio. Taken together, our data suggested that SiO2 NPs induced ROS-mediated autophagy in MRC-5 cells as a possible mechanism of cell survival. PMID:26690408

  4. Encapsulating magnetic and fluorescent mesoporous silica into thermosensitive chitosan microspheres for cell imaging and controlled drug release in vitro.

    PubMed

    Gui, Rijun; Wang, Yanfeng; Sun, Jie

    2014-01-01

    In this study, for the first time, multifunctional inorganic/organic core/shell hybrid microspheres consisted of Fe3O4 nanoparticles/CdTe quantum dots dual-embedded mesoporous silica nanocomposites (MQ-MSN) as cores and P(N-isopropylacrylamide)-graft-Chitosan microgels (PNIPAM-g-CS) as shells were prepared by copolymerization of NIPAM and CS in the presence of MQ-MSN. The preparation of microspheres (i.e., MQ-MSN/PNIPAM-g-CS) included three stages. First, Fe3O4/CdTe nanocomposites (MQ NCs) were prepared by self-assembly of electrostatic adsorption. Second, MQ NCs were encapsulated into silica spheres by modified Stöber method to obtain MQ-MSN. Third, NIPAM monomers were initiated to fabricate PNIPAM networks with MQ-MSN distributed below the lower critical solution temperature (LCST) of PNIPAM, and then PNIPAM reacted with CS to form PNIPAM-g-CS copolymers above the LCST, meanwhile the PNIPAM networks collapsed to form microspheres, resulting in the MQ-MSN encapsulated into microspheres. The microspheres were systematically characterized, displaying perfect magnetic/fluorescent properties and thermo-sensitivity. HepG2 cancer cells treated with the microspheres revealed bright fluorescence imaging. Both the efficiency and capacity of Adriamycin (ADM) loaded into the microspheres were gradually increased with ADM concentration increasing. The ADM cumulative release in vitro from ADM-loaded microspheres was significant at a higher temperature (or a lower pH). The released ADM still maintained high anticancer activity, and the blank microsphere carriers hardly produced toxicity to HepG2 cells. Hence, the multifunctional microspheres exhibited a promising application especially as thermo/pH-sensitive drug carriers for in vivo therapy. PMID:24060924

  5. 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

  6. 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

  7. 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

  8. 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.

  9. 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

  10. Precise diagnosis in different scenarios using photoacoustic and fluorescence imaging with dual-modality nanoparticles.

    PubMed

    Peng, Dong; Du, Yang; Shi, Yiwen; Mao, Duo; Jia, Xiaohua; Li, Hui; Zhu, Yukun; Wang, Kun; Tian, Jie

    2016-08-14

    Photoacoustic imaging and fluorescence molecular imaging are emerging as important research tools for biomedical studies. Photoacoustic imaging offers both strong optical absorption contrast and high ultrasonic resolution, and fluorescence molecular imaging provides excellent superficial resolution, high sensitivity, high throughput, and the ability for real-time imaging. Therefore, combining the imaging information of both modalities can provide comprehensive in vivo physiological and pathological information. However, currently there are limited probes available that can realize both fluorescence and photoacoustic imaging, and advanced biomedical applications for applying this dual-modality imaging approach remain underexplored. In this study, we developed a dual-modality photoacoustic-fluorescence imaging nanoprobe, ICG-loaded Au@SiO2, which was uniquely designed, consisting of gold nanorod cores and indocyanine green with silica shell spacer layers to overcome fluorophore quenching. This nanoprobe was examined by both PAI and FMI for in vivo imaging on tumor and ischemia mouse models. Our results demonstrated that the nanoparticles can specifically accumulate at the tumor and ischemic areas and be detected by both imaging modalities. Moreover, this dual-modality imaging strategy exhibited superior advantages for a precise diagnosis in different scenarios. The new nanoprobe with the dual-modality imaging approach holds great potential for diagnosis and stage classification of tumor and ischemia related diseases. PMID:27406825

  11. 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.

  12. Visual and fluorescent detection of acetamiprid based on the inner filter effect of gold nanoparticles on ratiometric fluorescence quantum dots.

    PubMed

    Yan, Xu; Li, Hongxia; Li, Yang; Su, Xingguang

    2014-12-10

    In this work, we develop a simple and rapid sensing method for the visual and fluorescent detection of acetamiprid (AC) based on the inner-filter effect (IFE) of gold nanoparticles (AuNPs) on ratiometric fluorescent quantum dots (RF-QDs). The RF-QDs based dual-emission nanosensor was fabricated by assembling green emissive QDs (QDs539nm, λem=539 nm) on the surface of red emissive QDs (QDs661nm, λem=661 nm)-doped silica microspheres. The photoluminescence (PL) intensity of RF-QDs could be quenched by AuNPs based on IFE. Acetamiprid can adsorb on the surface of AuNPs due to its cyano group that has good affinity with gold, which could induce the aggregation of AuNPs accompanying color change from red to blue. Thus, the IFE of AuNPs on RF-QDs was weakened and the PL intensity of RF-QDs was recovered accordingly. Under the optimized conditions, the PL intensity of the RF-QDs/AuNPs system was proportional to the concentration of AC in the range of 0.025-5.0 μg mL(-1), with a detection limit of 16.8 μg L(-1). The established method had been used for AC detection in environmental and agricultural samples with satisfactory results. PMID:25441897

  13. Core-shell microcapsules of solid lipid nanoparticles and mesoporous silica for enhanced oral delivery of curcumin.

    PubMed

    Kim, Sanghoon; Diab, Roudayna; Joubert, Olivier; Canilho, Nadia; Pasc, Andreea

    2016-04-01

    Newly designed microcapsules (MC) combining a core of solid lipid nanoparticle (SLN) and a mesoporous silica shell have been developed and explored as oral delivery system of curcumin (CU). CU-loaded MC (MC-CU) are 2μm sized and have a mesoporous silica shell of 0.3μm thickness with a wormlike structure as characterized by small angle X-ray scattering (SAXS), nitrogen adsorption/desorption and transmission electron microscopy (TEM) measurements. It was found that SLN acts as reservoir of curcumin while the mesoporous shell insures the protection and the controlled release of the drug. MC-CU displayed a pH-dependent in vitro release profile with marked drug retention at pH 2.8. Neutral red uptake assay together with confocal laser scanning microscopy (CLSM) showed a good cell tolerance to MC-CU at relatively high concentration of inert materials. Besides, the cell-uptake test revealed that fluorescent-MC were well internalized into Caco-2 cells, confirming the possibility to use MC for gut cells targeting. These findings suggest that organic core-silica shell microcapsules are promising drug delivery systems with enhanced bioavailability for poorly soluble drugs. PMID:26752213

  14. 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

    Invited for the cover of this issue are Jean-Yves Winum and co-workers at University of Montpellier (France) and University of Florence (Italy). The image depicts the multivalency approach applied to zinc metalloenzyme carbonic anhydrases. Read the full text of the article at 10.1002/chem.201501037. PMID:26061872

  15. NEAR-IR TWO PHOTON MICROSCOPY IMAGING OF SILICA NANOPARTICLES FUNCTIONALIZED WITH ISOLATED SENSITIZED Yb(III) CENTERS

    SciTech Connect

    Lapadula, Giuseppe; Bourdolle, Adrien; Allouche, Florian; Conley, Matthew P.; Maron, Laurent; Lukens, Wayne W.; Guyot, Yannick; Andraud, Chantal; Brasselet, Sophie; Copé; ret, Christophe; Maury, Olivier; Andersen, Richard A.

    2013-01-12

    Bright nano objects emitting in the near infrared with a maximal cross section of 41.4 x 103 GM (Goppert Mayer), were prepared by implanting ca. 180 4,4 diethylaminostyryl 2,2 bipyridine (DEAS) Yb(III) complexes on the surface of 12 nm silica nanoparticles. The surface complexes ([DEAS Ln SiO2], Ln =Y,Yb) were characterized using IR, solid state NMR, UV Vis, EXAFS spectroscopies in combination with the preparation and characterization of similar molecular analogues by analytical techniques (IR, solution NMR, UV Vis, X ray crystallography) as well as DFT calculations. Starting from the partial dehydroxylation of the silica at 700 C on high vacuum having 0.8 OH.nm 2, the grafting of Ln(N(SiMe3)2)3 generate ≤SiO Ln(N(SiMe3)2)2, which upon thermal step and coordination of the DEAS chromophore yields (≤SiO)3Ln(DEAS). Surface and molecular analogues display similar properties, in terms of DEAS binding constants absorption maxima and luminescence properties (intense emission band assigned to a ligand centered CT fluorescence and life time) in the solid state, consistent with the molecular nature of the surface species. The densely functionalized nanoparticles can be dispersed via ultra-sonication in small ca. 15-20 nm aggregates (1 to 6 elementary particles) that were detected using two photon microscopy imaging at 720 nm excitation, making them promising nano objects for bio imaging.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. Fluorescence spectroscopy of individual semiconductor nanoparticles in different ethylene glycols.

    PubMed

    Flessau, Sandra; Wolter, Christopher; Pöselt, Elmar; Kröger, Elvira; Mews, Alf; Kipp, Tobias

    2014-06-14

    The optical properties of single colloidal semiconductor nanoparticles (NPs) are considerably influenced by the direct environment of the NPs. Here, the influence of different liquid and solid glycol matrices on CdSe-based NPs is investigated. Since the fluorescence of individual NPs varies from one NP to another, it is highly desirable to study the very same individual NPs in different matrices. This was accomplished by immobilizing NPs in a liquid cell sample holder or in microfluidic devices. The samples have been investigated by space-resolved wide-field fluorescence microscopy and energy- and time-resolved confocal scanning fluorescence microscopy with respect to fluorescence intensities, emission energies, blinking behavior, and fluorescence decay dynamics of individual NPs. During the measurements the NPs were exposed to air, to liquid ethylene glycols H(OCH2CH2)nOH (also called EGn) with different chain lengths (1 ≤ n ≤ 7), to liquid 2-methylpentane-2,3-diol, or to solid polyethylene oxide. It was found that EG6-7 (also known as PEG 300) is very well suited as a liquid matrix or solvent for experiments that correlate chemical and physical modifications of the surface and of the immediate environment of individual NPs to their fluorescence properties since it leads to intense and stable fluorescence emission of the NPs. PMID:24788878

  3. Synthesis of fluorescent carbon nanoparticles directly from active carbon via a one-step ultrasonic treatment

    SciTech Connect

    Li, Haitao; He, Xiaodie; Liu, Yang; Yu, Hang; Kang, Zhenhui; Lee, Shuit-Tong

    2011-01-15

    Water-soluble fluorescent carbon nanoparticles were synthesized directly from active carbon by a one-step hydrogen peroxide-assisted ultrasonic treatment. The carbon nanoparticles were characterized by transmission electron microscopy, optical fluorescent microscopy, fluorescent spectroscopy, Fourier transform infrared spectroscopy and ultraviolet-visible spectrophotometer. The results showed that the surface of carbon nanoparticles was rich of hydroxyl groups resulting in high hydrophilicity. The carbon nanoparticles could emit bright and colorful photoluminescence covering the entire visible-to-near infrared spectral range. Furthermore, these carbon nanoparticles also had excellent up-conversion fluorescent properties.

  4. 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

  5. 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

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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

  11. Fluorescent Boronic Acid Polymer Grafted on Silica Particles for Affinity Separation of Saccharides

    PubMed Central

    2014-01-01

    Boronic acid affinity gels are important for effective separation of biological active cis-diols, and are finding applications both in biotech industry and in biomedical research areas. To increase the efficacy of boronate affinity separation, it is interesting to introduce repeating boronic acid units in flexible polymer chains attached on solid materials. In this work, we synthesize polymer brushes containing boronic acid repeating units on silica gels using surface-initiated atom transfer radical polymerization (ATRP). A fluorescent boronic acid monomer is first prepared from an azide-tagged fluorogenic boronic acid and an alkyne-containing acrylate by Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction (the CuAAC click chemistry). The boronic acid monomer is then grafted to the surface of silica gel modified with an ATRP initiator. The obtained composite material contains boronic acid polymer brushes on surface and shows favorable saccharide binding capability under physiological pH conditions, and displays interesting fluorescence intensity change upon binding fructose and glucose. In addition to saccharide binding, the flexible polymer brushes on silica also enable fast separation of a model glycoprotein based on selective boronate affinity interaction. The synthetic approach and the composite functional material developed in this work should open new opportunities for high efficiency detection, separation, and analysis of not only simple saccharides, but also glycopeptides and large glycoproteins. PMID:24444898

  12. Fluorescent boronic acid polymer grafted on silica particles for affinity separation of saccharides.

    PubMed

    Xu, Zhifeng; Uddin, Khan Mohammad Ahsan; Kamra, Tripta; Schnadt, Joachim; Ye, Lei

    2014-02-12

    Boronic acid affinity gels are important for effective separation of biological active cis-diols, and are finding applications both in biotech industry and in biomedical research areas. To increase the efficacy of boronate affinity separation, it is interesting to introduce repeating boronic acid units in flexible polymer chains attached on solid materials. In this work, we synthesize polymer brushes containing boronic acid repeating units on silica gels using surface-initiated atom transfer radical polymerization (ATRP). A fluorescent boronic acid monomer is first prepared from an azide-tagged fluorogenic boronic acid and an alkyne-containing acrylate by Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction (the CuAAC click chemistry). The boronic acid monomer is then grafted to the surface of silica gel modified with an ATRP initiator. The obtained composite material contains boronic acid polymer brushes on surface and shows favorable saccharide binding capability under physiological pH conditions, and displays interesting fluorescence intensity change upon binding fructose and glucose. In addition to saccharide binding, the flexible polymer brushes on silica also enable fast separation of a model glycoprotein based on selective boronate affinity interaction. The synthetic approach and the composite functional material developed in this work should open new opportunities for high efficiency detection, separation, and analysis of not only simple saccharides, but also glycopeptides and large glycoproteins. PMID:24444898

  13. Gold nanoparticle based surface enhanced fluorescence for detection of organophosphorus agents

    NASA Astrophysics Data System (ADS)

    Dasary, Samuel S. R.; Rai, Uma S.; Yu, Hongtao; Anjaneyulu, Yerramilli; Dubey, Madan; Ray, Paresh Chandra

    2008-07-01

    Organophosphorus agents (OPA) represent a serious concern to public safety as nerve agents and pesticides. Here we report the development of gold nanoparticle based surface enhanced fluorescence (NSEF) spectroscopy for rapid and sensitive screening of organophosphorus agents. Fluorescent from Eu 3+ ions that are bound within the electromagnetic field of gold nanoparticles exhibit a strong enhancement. In the presence of OPA, Eu 3+ ions are released from the gold nanoparticle surface and thus a very distinct fluorescence signal change was observed. We discussed the mechanism of fluorescence enhancement and the role of OPA for fluorescence intensity change in the presence of gold nanoparticles.

  14. 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

  15. The internalization of fluorescence-labeled PLA nanoparticles by macrophages.

    PubMed

    Li, Fengjuan; Zhu, Aiping; Song, Xiaoli; Ji, Lijun; Wang, Juan

    2013-09-10

    Rhodamine B (RhB)-labeled PLA nanoparticles were prepared through surface grafting copolymerization of glycidyl methacrylate (GMA) onto PLA nanoparticles during the emulsion/evaporation process. RhB firstly interacts with sodium dodecyl sulfate (SDS) through electrostatic interaction to form hydrophobic complex (SDS-RhB). Due to the high-affinity of SDS-RhB with GMA, hydrophilic RhB can be successfully combined into PLA nanoparticles. The internalization of RhB-labeled PLA nanoparticles by macrophages was investigated with fluorescence microscope technology. The effects of the PLA nanoparticle surface nature and size on the internalization were investigated. The results indicate that the PLA particles smaller than 200 nm can avoid the uptake of phagocytosis. The bigger PLA particles (300 nm) with polyethylene glycol (PEG) surface showed less internalization by macrophage compared with those with poly(ethylene oxide-propylene oxide) copolymer (F127) or poly(vinyl alcohol) (PVA) surface. The "stealth" function of PEG on the PLA nanoparticles from internalization of macrophages due to the low protein adsorption is revealed by electrochemical impedance technology. PMID:23806816

  16. Thin-film silica sol-gels doped with ion responsive fluorescent lipid bilayers

    SciTech Connect

    Sasaki, D.Y.; Shea, L.E.; Sinclair, M.B.

    1999-01-12

    A metal ion sensitive, fluorescent lipid-b i layer material (5oA PSIDA/DSPC) was successfully immobilized in a silica matrix using a tetramethoxysilane (TMOS) sol-gel procedure. The sol-gel immobilization method was quantitative in the entrapment of seif-assembled Iipid-bilayers and yielded thin films for facile configuration to optical fiber piatforms. The silica matrix was compatible with the solvent sensitive lipid bilayers and provided physical stabilization as well as biological protection. Immobilization in the silica sol-gel produced an added benefit of improving the bilayer's metal ion sensitivity by up to two orders of magnitude. This enhanced performance was attributed to a preconcentrator effect from the anionic surface of the silica matrix. Thin gels (193 micron thickness) were coupled to a bifurcated fiber optic bundle to produce a metal ion sensor probe. Response times of 10 - 15 minutes to 0.1 M CUCIZ were realized with complete regeneration of the sensor using an ethylenediarninetetraacetic acid (EDTA) solution.

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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

  3. Fluorescent monodisperse spherical particles based on mesoporous silica containing rhodamine 6G

    NASA Astrophysics Data System (ADS)

    Trofimova, E. Yu.; Grudinkin, S. A.; Kukushkina, Yu. A.; Kurdyukov, D. A.; Medvedev, A. V.; Yagovkina, M. A.; Golubev, V. G.

    2012-06-01

    Fluorescent monodisperse spherical silica (SiO2) particles with a regular mesoporous structure containing encapsulated Rhodamine 6G (R6G) dye have been synthesized. The as-synthesized particles have been coated with SiO2 and SiO2-CTAB (cetyltrimethylammonium bromide, C16H33N(CH3)3Br) shells in order to prevent uncontrolled release of the dye from pores. The kinetics of R6G release from the pores of silica particles has been studied. It has been found that the particles synthesized by adding CTAB and R6G to the reaction mixture, as well as the particles coated with the SiO2-CTAB shell, are characterized by the maximum duration of dye release from the pores, which is probably associated with the formation of chemical bonds between R6G and CTAB molecules.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. 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

  10. Urease immobilized fluorescent gold nanoparticles for urea sensing.

    PubMed

    Parashar, Upendra Kumar; Nirala, Narsingh R; Upadhyay, Chandan; Saxena, P S; Srivastava, Anchal

    2015-05-01

    We report a surfactant-free synthesis of monodispersed gold nanoparticles (AuNPs) with average size of 15 nm. An approach for visual and fluorescent sensing of urea in aqueous solution based on shift in surface plasmon band (SPB) maxima as well as quench in fluorescence intensity. To enable the urea detection, we functionalized the thiol-capped gold nanoparticles with urease, the enzyme specific to urea using carbodiimide chemistry. The visible color changed of the gold colloidal solution from red to blue (or purple); this was evident from quenching in absorbance and fluorescence intensity, is the principle applied here for the sensing of urea. The solution turns blue when the urea concentration exceeds 8 mg/dL which reveals visual lower detection limit. The lower detection limits governed by the fluorescence quenching were found 5 mg/dL (R(2) = 0.99) which is highly sensitive and selective compared to shift in SPB maxima. The approach depicted here seems to be important in clinical diagnosis. PMID:25809996

  11. 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.

  12. Optical imaging-guided cancer therapy with fluorescent nanoparticles

    PubMed Central

    Jiang, Shan; Gnanasammandhan, Muthu Kumara; Zhang, Yong

    2010-01-01

    The diagnosis and treatment of cancer have been greatly improved with the recent developments in nanotechnology. One of the promising nanoscale tools for cancer diagnosis is fluorescent nanoparticles (NPs), such as organic dye-doped NPs, quantum dots and upconversion NPs that enable highly sensitive optical imaging of cancer at cellular and animal level. Furthermore, the emerging development of novel multi-functional NPs, which can be conjugated with several functional molecules simultaneously including targeting mo