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Sample records for acid poly ic

  1. Vaccine adjuvant uses of poly-IC and derivatives.

    PubMed

    Martins, Karen A O; Bavari, Sina; Salazar, Andres M

    2015-03-01

    Pathogen-associated molecular patterns (PAMPs) are stand-alone immunomodulators or 'danger signals,' that are increasingly recognized as critical components of many modern vaccines. Polyinosinic-polycytidylic acid (poly-IC) is a synthetic dsRNA that can activate multiple elements of the host defense in a pattern that parallels that of a viral infection. When properly combined with an antigen, it can be utilized as a PAMP-adjuvant, resulting in modulation and optimization of the antigen-specific immune response. We briefly review the preclinical and clinical uses of poly-IC and two poly-IC derivatives, poly-IC12U (Ampligen) and poly-ICLC (Hiltonol), as vaccine adjuvants.

  2. Zoledronic acid induces dose-dependent increase of antigen-specific CD8 T-cell responses in combination with peptide/poly-IC vaccine.

    PubMed

    Park, Hye-Mi; Cho, Hyun-Il; Shin, Chang-Ae; Shon, Hyun-Jung; Kim, Tai-Gyu

    2016-03-04

    Zoledronic acid (ZA) is used for treating osteoporosis and for preventing skeletal fractures in cancer patients suffering from myeloma and prostate cancer. It is also reported to directly induce cancer cell apoptosis and indirectly modulate T-cell immune response as an antitumor agent. In this study, the effect of ZA following peptide/polyinosinic-polycytidylic acid (poly-IC) vaccination was investigated in a murine tumor model. The combination of ZA with peptide/poly-IC vaccine showed a synergistic effect on the induction of antigen-specific CD8 T-cell response. Three consecutive intravenous administrations of ZA was defined to induce the highest CD8 T-cell response. Further, total splenocyte counts and antigen-specific CD8 T-cell response gradually increased depending on the dose of ZA. In tumor-bearing mice, ZA showed a dose-dependent decrease of growth and prolonged survival. Treatment with ZA only decreased the number of CD11b(+)Gr1(+) myeloid cells in blood. Our results demonstrate that the use of ZA could improve antitumor immune responses induced by the peptide/poly-IC vaccine.

  3. The effect of synthetic homopolymer poly I:C on the synthesis of nucleic acids, protein and interferon in spleen cells normally and with radiation

    NASA Technical Reports Server (NTRS)

    Antropova, Y. N.; Konstantinova, I. V.; Fuks, B. B.; Talosh, M. Y.; Veysfeyler, Y. K.

    1974-01-01

    A comparative study is reported of the effect of the synthetic homopolymer poly I:C and Newcastle Disease virus on the synthesis of RNA, DNA, total protein and interferon in the spleen of nonradiated and radiated mice. In radiated animals, poly I:C and NDV had no stimulating effect on the synthesis of RNA; administration of both inducers to radiated mice did not significantly affect the content of lymphoid cellular elements in the spleen. However, while reduction of RNA synthesis, caused by radiation, also increases slightly under the effect of poly I:C and the virus, the synthesis of interferon in spleen cells and in the entire body is activated.

  4. Poly-IC preconditioning protects against cerebral and renal ischemia-reperfusion injury.

    PubMed

    Packard, Amy E B; Hedges, Jason C; Bahjat, Frances R; Stevens, Susan L; Conlin, Michael J; Salazar, Andres M; Stenzel-Poore, Mary P

    2012-02-01

    Preconditioning induces ischemic tolerance, which confers robust protection against ischemic damage. We show marked protection with polyinosinic polycytidylic acid (poly-IC) preconditioning in three models of murine ischemia-reperfusion injury. Poly-IC preconditioning induced protection against ischemia modeled in vitro in brain cortical cells and in vivo in models of brain ischemia and renal ischemia. Further, unlike other Toll-like receptor (TLR) ligands, which generally induce significant inflammatory responses, poly-IC elicits only modest systemic inflammation. Results show that poly-IC is a new powerful prophylactic treatment that offers promise as a clinical therapeutic strategy to minimize damage in patient populations at risk of ischemic injury.

  5. Poly I:C induces development of diabetes mellitus in BB rat.

    PubMed

    Sobel, D O; Newsome, J; Ewel, C H; Bellanti, J A; Abbassi, V; Creswell, K; Blair, O

    1992-04-01

    Polyinosinic polycytidilic acid (poly I:C), an inducer of alpha-interferon, accelerates the development of diabetes in diabetes-prone (DP) BioBreeding (BB) rats. This study investigates the effect of administering poly I:C to a diabetes-resistant (DR) strain of BB rats. We compared the incidence of diabetes, the degree of insulitis, the number of NK cells, helper-inducer cells, cytotoxic-suppressor cells, Ia+ T cells, RT6.1+ T cells, and NK cell bioactivity in DR rats treated with saline and with a 5 micrograms/g body wt (poly-5) dose and a 10 micrograms/g body wt (poly-10) dose of poly I:C. The incidence of diabetes was also compared with that of DP rats receiving poly-5. We found that both doses of poly I:C significantly induce the development of diabetes in the DR BB rat. However, treatment of DR rats with the higher dose induces a greater rate of development of diabetes and earlier onset of diabetes than the lower poly-5 dose. The rate of diabetes development and the mean age of onset were similar in poly-10-treated DR and poly-5-treated DP rats. A significant degree of insulitis occurred in all the poly I:C-treated DR rats, even those not developing diabetes. Peripheral blood NK cell number was greater in poly I:C than in saline-treated rats, after 2 wk of treatment and when killed. The percentage of OX19+ peripheral blood mononuclear cells expressing RT6.1 allotype or Ia antigen were similar in poly I:C- and saline-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Poly IC triggers a cathepsin D- and IPS-1-dependent pathway to enhance cytokine production and mediate dendritic cell necroptosis.

    PubMed

    Zou, Jian; Kawai, Taro; Tsuchida, Tetsuo; Kozaki, Tatsuya; Tanaka, Hiroki; Shin, Kyung-Sue; Kumar, Himanshu; Akira, Shizuo

    2013-04-18

    RIG-I-like receptors (RLRs) sense virus-derived RNA or polyinosinic-polycytidylic acid (poly IC) to exert antiviral immune responses. Here, we examine the mechanisms underlying the adjuvant effects of poly IC. Poly IC was taken up by dendritic cells (DCs), and it induced lysosomal destabilization, which, in turn, activated an RLR-dependent signaling pathway. Upon poly IC stimulation, cathepsin D was released into the cytoplasm from the lysosome to interact with IPS-1, an adaptor molecule for RLRs. This interaction facilitated cathepsin D cleavage of caspase 8 and the activation of the transcription factor NF-κB, resulting in enhanced cytokine production. Further recruitment of the kinase RIP-1 to this complex initiated the necroptosis of a small number of DCs. HMGB1 released by dying cells enhanced IFN-β production in concert with poly IC. Collectively, these findings suggest that cathepsin D-triggered, IPS-1-dependent necroptosis is a mechanism that propagates the adjuvant efficacy of poly IC.

  7. Improved Social Interaction, Recognition and Working Memory with Cannabidiol Treatment in a Prenatal Infection (poly I:C) Rat Model.

    PubMed

    Osborne, Ashleigh L; Solowij, Nadia; Babic, Ilijana; Huang, Xu-Feng; Weston-Green, Katrina

    2017-03-22

    Neuropsychiatric disorders such as schizophrenia are associated with cognitive impairment, including learning, memory and attention deficits. Antipsychotic drugs are limited in their efficacy to improve cognition; therefore, new therapeutic agents are required. Cannabidiol (CBD), the non-intoxicating component of cannabis, has anti-inflammatory, neuroprotective and antipsychotic-like properties; however, its ability to improve the cognitive deficits of schizophrenia remains unclear. Using a prenatal infection model, we examined the effect of chronic CBD treatment on cognition and social interaction. Time-mated pregnant Sprague-Dawley rats (n=16) were administered polyinosinic-polycytidilic acid (poly I:C) (POLY; 4 mg/kg) or saline (CONT) at gestation day 15. Male offspring (PN56) were injected twice daily with 10 mg/kg CBD (CONT+CBD, POLY+CBD; n=12 per group) or vehicle (VEH; CONT+VEH, POLY+VEH; n=12 per group) for 3 weeks. Body weight, food and water intake was measured weekly. The Novel Object Recognition and rewarded T-maze alternation tests assessed recognition and working memory, respectively, and the social interaction test assessed sociability. POLY+VEH offspring exhibited impaired recognition and working memory, and reduced social interaction compared to CONT+VEH offspring (p<0.01). CBD treatment significantly improved recognition, working memory and social interaction deficits in the poly I:C model (p<0.01 vs POLY+VEH), did not affect total body weight gain, food or water intake, and had no effect in control animals (all p>0.05). In conclusion, chronic CBD administration can attenuate the social interaction and cognitive deficits induced by prenatal poly I:C infection. These novel findings present interesting implications for potential use of CBD in treating the cognitive deficits and social withdrawal of schizophrenia.Neuropsychopharmacology advance online publication, 22 March 2017; doi:10.1038/npp.2017.40.

  8. Polymeric nanoparticles for co-delivery of synthetic long peptide antigen and poly IC as therapeutic cancer vaccine formulation.

    PubMed

    Rahimian, Sima; Fransen, Marieke F; Kleinovink, Jan Willem; Christensen, Jonatan Riis; Amidi, Maryam; Hennink, Wim E; Ossendorp, Ferry

    2015-04-10

    The aim of the current study was to develop a cancer vaccine formulation for treatment of human papillomavirus (HPV)-induced malignancies. Synthetic long peptides (SLPs) derived from HPV16 E6 and E7 oncoproteins have been used for therapeutic vaccination in clinical trials with promising results. In preclinical and clinical studies adjuvants based on mineral oils (such as incomplete Freund's adjuvant (IFA) and Montanide) are used to create a sustained release depot at the injection site. While the depot effect of mineral oils is important for induction of robust immune responses, their administration is accompanied with severe adverse and long lasting side effects. In order to develop an alternative for IFA family of adjuvants, polymeric nanoparticles (NPs) based on hydrophilic polyester (poly(d,l lactic-co-hydroxymethyl glycolic acid) (pLHMGA)) were prepared. These NPs were loaded with a synthetic long peptide (SLP) derived from HPV16 E7 oncoprotein and a toll like receptor 3 (TLR3) ligand (poly IC) by double emulsion solvent evaporation technique. The therapeutic efficacy of the nanoparticulate formulations was compared to that of HPV SLP+poly IC formulated in IFA. Encapsulation of HPV SLP antigen in NPs substantially enhanced the population of HPV-specific CD8+ T cells when combined with poly IC either co-encapsulated with the antigen or in its soluble form. The therapeutic efficacy of NPs containing poly IC in tumor eradication was equivalent to that of the IFA formulation. Importantly, administration of pLHMGA nanoparticles was not associated with adverse effects and therefore these biodegradable nanoparticles are excellent substitutes for IFA in cancer vaccines.

  9. Genetic differentiation of poly I:C from B:9-23 peptide induced experimental autoimmune diabetes.

    PubMed

    Paronen, Johanna; Liu, Edwin; Moriyama, Hiroaki; Devendra, Devasenan; Ide, Akane; Taylor, Robert; Yu, Liping; Miao, Dongmei; Melanitou, Evie; Eisenbarth, George S

    2004-06-01

    Type 1 diabetes is an immune-mediated disease, in which T cells of the adaptive immune system mediate beta cell destruction. Recently the innate immune system has been linked to etiopathogenesis of several autoimmune diseases including type 1 diabetes, as innate effector cells (e.g. dendritic cells, monocytes/macrophages and NK cells) can prime and promote or regulate (auto)immune responses. We have previously developed an experimental autoimmune diabetes (EAD) model with insulin peptide B:9-23 immunization in transgenic H-2(d)mice expressing the costimulatory molecule B7.1 in their islets (under the Rat Insulin Promotor, RIP). We compared the induction of diabetes with polyinosinic-polycytidylic acid (Poly I:C), a mimic of double stranded viral RNA versus insulin B:9-23 peptide in mice following backcrossing of the B7.1 transgene on to BALB/c mice from original B7.1 C57Bl/6 mice. We find that diabetes induction by Poly I:C is C57Bl/6 associated, whereas B:9-23 peptide induced diabetes and induction of insulin autoantibodies (IAA) are dependent on BALB/c genes. This B:9-23 peptide induced diabetes is consistent with MHC class II H-2(d)being necessary for the response to this peptide. Of note Poly I:C induction of diabetes was lost while B:9-23 induction was retained with backcrossing to BALB/c mice. Interaction of genes and environment (antigenic epitope and viral mimic) can be important in the pathogenesis of immune mediated diabetes and activation of the innate immune system (e.g. Poly I:C) may be one key determinant.

  10. Sensitivity of drug-resistant mutants of hepatitis B virus to poly-IC.

    PubMed

    Zhou, Q; Chen, E; Chen, L; Nong, Y; Cheng, X; He, M; Tang, H

    2014-01-01

    The long-term benefits of antiviral treatment are limited by the resistance of hepatitis B virus (HBV). However, the effect of interferon (IFN)α treatment on drug-resistant HBVs is so far unknown. We, therefore, investigated the effects of IFN-α inducer poly-IC on the replication of HBV mutants resistant to drugs such as lamivudine (LAM), adefovir dipivoxil (ADV) and entecavir (ETV) in mice. HBV DNA and HBV DNA intermediate (RI) were employed as markers of the virus replication and 2',5'-oligoadenylate synthase (OAS) mRNA as a marker of IFN-α/β induction. Poly-IC inhibited wtHBV replication and increased levels of OAS mRNA. Compared to the wt virus, the capacity of virus replication was reduced in most LAMr and ETVr mutants except those with mutations rtM(204V+L180M+V173L), and was similary in the ADVr mutants except rt(A121V+N236T). The virus replication was reduced after poly-IC treatment with LAMr and ADVr mutants similary to the wt virus. In contrast, ETVr mutants were resistant to the poly-IC treatment. In conclusion, the capacity of HBV replication and the sensitivity to IFN therapy are influenced by drug-resistant mutations. The IFN therapy may effectively inhibit HBV replication in particular in patients with LAMr or ADVr mutations but not in patients with ETVr mutations.

  11. Co-Administration of Poly I:C and ISCOMs Modifies Antigen Processing in Dendritic Cell Subsets and Enhances HIV Gag-Specific T Cell Immunity

    PubMed Central

    Quinn, Kylie M.; Yamamoto, Ayako; Costa, Andreia; Darrah, Patricia A.; Lindsay, Ross W.B.; Hegde, Sonia T.; Johnson, Teresa R.; Flynn, Barbara J.; Lore, Karin; Seder, Robert A.

    2013-01-01

    Currently approved adjuvants induce protective antibody responses but are more limited for generating cellular immunity. Here we assessed the effect of combining two adjuvants with distinct mechanisms of action on their ability to prime T cells; the TLR3 ligand, polyinosinic:polycytidylic acid (Poly I:C), and immunostimulatory complexes (ISCOMs). Each adjuvant was administered alone or together with HIV Gag protein (Gag) and the magnitude, quality and phenotype of Gag-specific T cell responses were assessed. For CD8 T cells, all adjuvants induced a comparable response magnitude, but combining Poly I:C with ISCOMs induced a high frequency of CD127+, IL-2 producing cells with decreased expression of Tbet compared to either adjuvant alone. For CD4 T cells, combining Poly I:C and ISCOMs increased the frequency of multifunctional cells, producing IFNγ, IL-2 and TNF, and the total magnitude of the response compared to either adjuvant alone. CD8 or CD4 T cell responses induced by both adjuvants mediated protection against Gag-expressing Listeria monocytogenes or vaccinia viral infections. Poly I:C and ISCOMs can alter antigen uptake and/or processing and we therefore used fluorescently labeled HIV Gag and DQ-OVA to assess these mechanisms respectively in multiple DC subsets. Poly I:C promoted uptake and retention of antigen, while ISCOMs enhanced antigen degradation. Combining Poly I:C and ISCOMs caused substantial death of DCs but persistence of degraded antigen. These data illustrate how combining adjuvants, such as Poly I:C and ISCOMs that modulate antigen processing and have potent innate activity, can enhance the magnitude, quality and phenotype of T cell immunity. PMID:24089189

  12. Engagement of Fas on Macrophages Modulates Poly I:C induced cytokine production with specific enhancement of IP-10.

    PubMed

    Lyons, Caitriona; Fernandes, Philana; Fanning, Liam J; Houston, Aileen; Brint, Elizabeth

    2015-01-01

    Viral double-stranded RNA (dsRNA) is recognised by pathogen recognition receptors such as Toll-Like Receptor 3 (TLR3) and retinoic acid inducible gene-I (RIG-I), and results in cytokine and interferon production. Fas, a well characterised death receptor, has recently been shown to play a role in the inflammatory response. In this study we investigated the role of Fas in the anti-viral immune response. Stimulation of Fas on macrophages did not induce significant cytokine production. However, activation of Fas modified the response of macrophages to the viral dsRNA analogue poly I:C. In particular, poly I:C-induced IP-10 production was significantly enhanced. A similar augmentation of IP-10 by Fas was observed following stimulation with both poly A:U and Sendai virus. Fas activation suppressed poly I:C-induced phosphorylation of the MAP kinases p38 and JNK, while overexpression of the Fas adaptor protein, Fas-associated protein with death domain (FADD), activated AP-1 and inhibited poly I:C-induced IP-10 production. Consistent with an inhibitory role for AP-1 in IP-10 production, mutation of the AP-1 binding site on the IP-10 promoter resulted in augmented poly I:C-induced IP-10. These results demonstrate that engagement of the Fas receptor plays a role in modifying the innate immune response to viral RNA.

  13. Mouse CD8alpha+ DCs and human BDCA3+ DCs are major producers of IFN-lambda in response to poly IC.

    PubMed

    Lauterbach, Henning; Bathke, Barbara; Gilles, Stefanie; Traidl-Hoffmann, Claudia; Luber, Christian A; Fejer, György; Freudenberg, Marina A; Davey, Gayle M; Vremec, David; Kallies, Axel; Wu, Li; Shortman, Ken; Chaplin, Paul; Suter, Mark; O'Keeffe, Meredith; Hochrein, Hubertus

    2010-11-22

    Polyinosinic:polycytidylic acid (poly IC), a double-stranded RNA, is an effective adjuvant in vivo. IFN-λs (also termed IL-28/29) are potent immunomodulatory and antiviral cytokines. We demonstrate that poly IC injection in vivo induces large amounts of IFN-λ, which depended on hematopoietic cells and the presence of TLR3 (Toll-like receptor 3), IRF3 (IFN regulatory factor 3), IRF7, IFN-I receptor, Fms-related tyrosine kinase 3 ligand (FL), and IRF8 but not on MyD88 (myeloid differentiation factor 88), Rig-like helicases, or lymphocytes. Upon poly IC injection in vivo, the IFN-λ production by splenocytes segregated with cells phenotypically resembling CD8α(+) conventional dendritic cells (DCs [cDCs]). In vitro experiments revealed that CD8α(+) cDCs were the major producers of IFN-λ in response to poly IC, whereas both CD8α(+) cDCs and plasmacytoid DCs produced large amounts of IFN-λ in response to HSV-1 or parapoxvirus. The nature of the stimulus and the cytokine milieu determined whether CD8α(+) cDCs produced IFN-λ or IL-12p70. Human DCs expressing BDCA3 (CD141), which is considered to be the human counterpart of murine CD8α(+) DCs, also produced large amounts of IFN-λ upon poly IC stimulation. Thus, IFN-λ production in response to poly IC is a novel function of mouse CD8α(+) cDCs and their human equivalents.

  14. Transcriptomic Analysis Identifies Candidate Genes and Gene Sets Controlling the Response of Porcine Peripheral Blood Mononuclear Cells to Poly I:C Stimulation.

    PubMed

    Wang, Jiying; Wang, Yanping; Wang, Huaizhong; Wang, Haifei; Liu, Jian-Feng; Wu, Ying; Guo, Jianfeng

    2016-05-03

    Polyinosinic-polycytidylic acid (poly I:C), a synthetic dsRNA analog, has been demonstrated to have stimulatory effects similar to viral dsRNA. To gain deep knowledge of the host transcriptional response of pigs to poly I:C stimulation, in the present study, we cultured and stimulated peripheral blood mononuclear cells (PBMC) of piglets of one Chinese indigenous breed (Dapulian) and one modern commercial breed (Landrace) with poly I:C, and compared their transcriptional profiling using RNA-sequencing (RNA-seq). Our results indicated that poly I:C stimulation can elicit significantly differentially expressed (DE) genes in Dapulian (g = 290) as well as Landrace (g = 85). We also performed gene set analysis using the Gene Set Enrichment Analysis (GSEA) package, and identified some significantly enriched gene sets in Dapulian (g = 18) and Landrace (g = 21). Most of the shared DE genes and gene sets were immune-related, and may play crucial rules in the immune response of poly I:C stimulation. In addition, we detected large sets of significantly DE genes and enriched gene sets when comparing the gene expression profile between the two breeds, including control and poly I:C stimulation groups. Besides immune-related functions, some of the DE genes and gene sets between the two breeds were involved in development and growth of various tissues, which may be correlated with the different characteristics of the two breeds. The DE genes and gene sets detected herein provide crucial information towards understanding the immune regulation of antiviral responses, and the molecular mechanisms of different genetic resistance to viral infection, in modern and indigenous pigs.

  15. POLY IC IS THE MOST EFFECTIVE TOLL-LIKE RECEPTOR ADJUVANT FOR SIV GAG PROTEIN INDUCED T CELL RESPONSES IN NON-HUMAN PRIMATES

    PubMed Central

    Park, Haesun; Adamson, Lauren; Ha, Tae; Mullen, Karl; Hagen, Shoko I; Nogueron, Arys; Sylwester, Andrew W.; Axthelm, Michael K.; Legasse, Al; Piatak, Michael; Lifson, Jeffrey D.; McElrath, Juliana M.; Picker, Louis J.; Seder, Robert A.

    2013-01-01

    Prime-boost immunization with heterologous vaccines elicits potent cellular immunity. Here, we assessed the influence of various TLR ligands on SIV Gag-specific T cell immunity and protection following prime-boost immunization. Rhesus macaques (RM) were primed with SIV Gag protein emulsified in montanide ISA51 with or without TLR3 (polyinosinic-polycytidylic acid (Poly IC)), TLR4 (monophosphoryl lipid A (MPL)), TLR7/8, TLR9 (CpG) or TLR3 (Poly IC) combined with TLR7/8 ligands, then boosted with replication defective adenovirus 5 expressing SIV Gag (rAd5-Gag). After priming, RM that received SIV Gag protein plus Poly IC developed significantly higher frequencies of SIV Gag-specific CD4+ Th1 responses in blood and bronchoalveolar lavage fluid lymphocytes (BAL) compared to all other adjuvants, and low-level SIV Gag-specific CD8+ T cell responses. After the rAd5-Gag boost, the magnitude and breadth of SIV Gag-specific CD8+ T cell responses were significantly increased in RM primed with SIV Gag protein plus Poly IC, with or without the TLR7/8 ligand, or CpG. However, the anamnestic, SIV Gag-specific CD8+ T cell response to SIVmac251 challenge was not significantly enhanced by SIV Gag protein priming with any of the adjuvants. In contrast, the anamnestic SIV Gag-specific CD4+ T cell response in BAL was enhanced by SIV Gag protein priming with Poly IC or CpG, which correlated with partial control of early viral replication after SIVmac251 challenge. These results demonstrate that prime-boost vaccination with SIV Gag protein/Poly IC improves magnitude, breadth, and durability of CD4+ T cell immune responses, which may have a role in control of SIV viral replication. PMID:23509365

  16. Transcriptomic Analysis Identifies Candidate Genes and Gene Sets Controlling the Response of Porcine Peripheral Blood Mononuclear Cells to Poly I:C Stimulation

    PubMed Central

    Wang, Jiying; Wang, Yanping; Wang, Huaizhong; Wang, Haifei; Liu, Jian-Feng; Wu, Ying; Guo, Jianfeng

    2016-01-01

    Polyinosinic-polycytidylic acid (poly I:C), a synthetic dsRNA analog, has been demonstrated to have stimulatory effects similar to viral dsRNA. To gain deep knowledge of the host transcriptional response of pigs to poly I:C stimulation, in the present study, we cultured and stimulated peripheral blood mononuclear cells (PBMC) of piglets of one Chinese indigenous breed (Dapulian) and one modern commercial breed (Landrace) with poly I:C, and compared their transcriptional profiling using RNA-sequencing (RNA-seq). Our results indicated that poly I:C stimulation can elicit significantly differentially expressed (DE) genes in Dapulian (g = 290) as well as Landrace (g = 85). We also performed gene set analysis using the Gene Set Enrichment Analysis (GSEA) package, and identified some significantly enriched gene sets in Dapulian (g = 18) and Landrace (g = 21). Most of the shared DE genes and gene sets were immune-related, and may play crucial rules in the immune response of poly I:C stimulation. In addition, we detected large sets of significantly DE genes and enriched gene sets when comparing the gene expression profile between the two breeds, including control and poly I:C stimulation groups. Besides immune-related functions, some of the DE genes and gene sets between the two breeds were involved in development and growth of various tissues, which may be correlated with the different characteristics of the two breeds. The DE genes and gene sets detected herein provide crucial information towards understanding the immune regulation of antiviral responses, and the molecular mechanisms of different genetic resistance to viral infection, in modern and indigenous pigs. PMID:26935416

  17. Microglia isolated from patients with glioma gain antitumor activities on poly (I:C) stimulation.

    PubMed

    Kees, Tim; Lohr, Jennifer; Noack, Johannes; Mora, Rodrigo; Gdynia, Georg; Tödt, Grischa; Ernst, Aurélie; Radlwimmer, Bernhard; Falk, Christine S; Herold-Mende, Christel; Régnier-Vigouroux, Anne

    2012-01-01

    The role of microglia, the brain-resident macrophages, in glioma biology is still a matter of debate. Clinical observations and in vitro studies in the mouse model indicate that microglia and macrophages that infiltrate the brain tumor tissue in high numbers play a tumor-supportive role. Here, we provide evidence that human microglia isolated from brain tumors indeed support tumor cell growth, migration, and invasion. However, after stimulation with the Toll-like receptor 3 agonist poly (I:C), microglia secrete factors that exerted toxic and suppressive effects on different glioblastoma cell lines, as assessed in cytotoxicity, migration, and tumor cell spheroid invasion assays. Remarkably, these effects were tumor-specific because the microglial factors impaired neither growth nor viability of astrocytes and neurons. Culture supernatants of tumor cells inhibited the poly (I:C) induction of this microglial M1-like, oncotoxic profile. Microglia stimulation before coculture with tumor cells circumvented the tumor-mediated suppression, as demonstrated by the ability to kill and phagocytose glioma cells. Our results show, for the first time to our knowledge, that human microglia exert tumor-supporting functions that are overridden by tumor-suppressing activities gained after poly (I:C) stimulation.

  18. Prenatal immune challenge in rats: altered responses to dopaminergic and glutamatergic agents, prepulse inhibition of acoustic startle, and reduced route-based learning as a function of maternal body weight gain after prenatal exposure to poly IC.

    PubMed

    Vorhees, Charles V; Graham, Devon L; Braun, Amanda A; Schaefer, Tori L; Skelton, Matthew R; Richtand, Neil M; Williams, Michael T

    2012-08-01

    Prenatal maternal immune activation has been used to test the neurodevelopmental hypothesis of schizophrenia. Most of the data are in mouse models; far less is available for rats. We previously showed that maternal weight change in response to the immune activator polyinosinic-polycytidylic acid (Poly IC) in rats differentially affects offspring. Therefore, we treated gravid Harlan Sprague-Dawley rats i.p. on embryonic day 14 with 8 mg/kg of Poly IC or Saline. The Poly IC group was divided into those that lost or gained the least weight, Poly IC (L), versus those that gained the most weight, Poly IC (H), following treatment. The study design controlled for litter size, litter sampling, sex distribution, and test experience. We found no effects of Poly IC on elevated zero maze, open-field activity, object burying, light-dark test, straight channel swimming, Morris water maze spatial acquisition, reversal, or shift navigation or spatial working or reference memory, or conditioned contextual or cued fear or latent inhibition. The Poly IC (H) group showed a significant decrease in the rate of route-based learning when visible cues were unavailable in the Cincinnati water maze and reduced prepulse inhibition of acoustic startle in females, but not males. The Poly IC (L) group exhibited altered responses to acute pharmacological challenges: exaggerated hyperactivity in response to (+)-amphetamine and an attenuated hyperactivity in response to MK-801. This model did not exhibit the cognitive, or latent inhibition deficits reported in Poly IC-treated rats but showed changes in response to drugs acting on neurotransmitter systems implicated in the pathophysiology of schizophrenia (dopaminergic hyperfunction and glutamatergic hypofunction).

  19. Zinc Oxide Nanoparticle-Poly I:C RNA Complexes: Implication as Therapeutics against Experimental Melanoma.

    PubMed

    Ramani, Meghana; Mudge, Miranda C; Morris, R Tyler; Zhang, Yuntao; Warcholek, Stanislaw A; Hurst, Miranda N; Riviere, Jim E; DeLong, Robert K

    2017-03-06

    There is current interest in harnessing the combined anticancer and immunological effect of nanoparticles (NPs) and RNA. Here, we evaluate the bioactivity of poly I:C (pIC) RNA, bound to anticancer zinc oxide NP (ZnO-NP) against melanoma. Direct RNA association to unfunctionalized ZnO-NP is shown by observing change in size, zeta potential, and absorption/fluorescence spectra upon complexation. RNA corona was visualized by transmission electron microscopy (TEM) for the first time. Binding constant (Kb = 1.6-2.8 g(-1) L) was determined by modified Stern-Volmer, absorption, and biological surface activity index analysis. The pIC-ZnO-NP complex increased cell death for both human (A375) and mouse (B16F10) cell lines and suppressed tumor cell growth in BALB/C-B16F10 mouse melanoma model. Ex vivo tumor analysis indicated significant molecular activity such as changes in the level of phosphoproteins JNK, Akt, and inflammation markers IL-6 and IFN-γ. High throughput proteomics analysis revealed zinc oxide and poly I:C-specific and combinational patterns that suggested possible utility as an anticancer and immunotherapeutic strategy against melanoma.

  20. Human platelets express Toll-like receptor 3 and respond to poly I:C.

    PubMed

    Anabel, Antonio-Santos; Eduardo, Pérez-Campos; Pedro Antonio, Hernández-Cruz; Carlos, Solórzano-Mata; Juana, Narváez-Morales; Honorio, Torres-Aguilar; Nicolás, Villegas-Sepúlveda; Sergio Roberto, Aguilar-Ruiz

    2014-12-01

    Platelets functions in hemostasis have been widely studied. Currently, growing evidence shows that platelets have also a role in the immune innate response. Recently, protein expression of Toll-like receptors (TLR's) 2, 4, 7, 8, and 9, and the presence of TLRs 1 and 6 mRNA in human platelets was described. Up to now the functionality of TLR-2, 4 and 9 in human platelets has been demonstrated. Due to the relevance of TLRs functions to PAMPS (pathogen-associated molecular patterns) recognizing, we evaluated the presence of TLR3 in human platelets founding low percentages of platelets expressing surface or intracellular TLR3 protein. The activation with thrombin induced an increase in the percentage of platelets expressing surface TLR3 and higher levels of TLR3 expression in the whole population. Human platelets responded to poly I:C by increasing [Ca(2+)]i, the percentages of cells expressing TLR4 and CD62P, and by releasing CXCL4 and IL-1β in comparison to unstimulated platelets. These results demonstrate that human platelets express TLR3 and are capable of responding to poly I:C, suggesting that these cells might influence the immune innate response when detecting viral dsRNA.

  1. Targeting the Immune System to Fight Cancer Using Chemical Receptor Homing Vectors Carrying Polyinosine/Cytosine (PolyIC).

    PubMed

    Levitzki, Alexander

    2012-01-01

    Cancer researchers have been looking for ways to harness the immune system and to reinstate immune surveillance, to kill cancer cells without collateral damage. Here we scan current approaches to targeting the immune system against cancer, and emphasize our own approach. We are using chemical vectors attached to a specific ligand, to introduce synthetic dsRNA, polyinosine/cytosine (polyIC), into tumors. The ligand binds to a receptor protein that is overexpressed on the surface of the tumor cells. Upon ligand binding, the receptor complex is internalized, introducing the polyIC into the cell. In this fashion a large amount of synthetic dsRNA can be internalized, leading to the activation of dsRNA-binding proteins, such as dsRNA dependent protein kinase (PKR), Toll-like receptor 3 (TLR3), retinoic acid-inducible gene I (RIG-1), and melanoma differentiation-associated gene 5 (MDA5). The simultaneous activation of these signaling proteins leads to the rapid demise of the targeted cell and to cytokine secretion. The cytokines lead to a strong bystander effect and to the recruitment of immune cells that converge upon the targeted cells. The bystander effects lead to the destruction of neighboring tumor cells not targeted themselves by the vector. Normal cells, being more robust than tumor cells, survive. This strategy has several advantages: (1) recruitment of the immune system is localized to the tumor. (2) The response is rapid, leading to fast tumor eradication. (3) The bystander effects lead to the eradication of tumor cells not harboring the target. (4) The multiplicity of pro-death signaling pathways elicited by PolyIC minimizes the likelihood of the emergence of resistance. In this chapter we focus on EGFR as the targeted receptor, which is overexpressed in many tumors. In principle, the strategy can be extended to other tumors that overexpress a protein that can be internalized by a ligand, which can be a small molecule, a single chain antibody, or an affibody.

  2. Maternal poly I:C exposure during pregnancy regulates TNF alpha, BDNF, and NGF expression in neonatal brain and the maternal-fetal unit of the rat.

    PubMed

    Gilmore, John H; Jarskog, L Fredrik; Vadlamudi, Swarooparani

    2005-02-01

    Maternal infection during pregnancy is associated with increased risk for neurodevelopmental disorders. Polyriboinosinic-polyribocytidilic acid (poly I:C) or saline was administered to rats to model maternal infection; levels of TNFalpha, brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF) were determined by ELISA. TNFalpha was significantly increased in maternal plasma, placenta, and amniotic fluid, while it was significantly decreased in fetal liver/spleen and neonatal brain. NGF and BDNF were significantly decreased in the placenta and fetal liver/spleen. There was no change in BDNF or NGF in the fetal or neonatal brain. Changes in TNFalpha, BDNF, and NGF after maternal exposure to poly I:C represent a potential mechanism through which maternal infection increases risk for neurodevelopmental disorders.

  3. Poly I:C adjuvanted inactivated swine influenza vaccine induces heterologous protective immunity in pigs.

    PubMed

    Thomas, Milton; Wang, Zhao; Sreenivasan, Chithra C; Hause, Ben M; Gourapura J Renukaradhya; Li, Feng; Francis, David H; Kaushik, Radhey S; Khatri, Mahesh

    2015-01-15

    Swine influenza is widely prevalent in swine herds in North America and Europe causing enormous economic losses and a public health threat. Pigs can be infected by both avian and mammalian influenza viruses and are sources of generation of reassortant influenza viruses capable of causing pandemics in humans. Current commercial vaccines provide satisfactory immunity against homologous viruses; however, protection against heterologous viruses is not adequate. In this study, we evaluated the protective efficacy of an intranasal Poly I:C adjuvanted UV inactivated bivalent swine influenza vaccine consisting of Swine/OH/24366/07 H1N1 and Swine/CO/99 H3N2, referred as PAV, in maternal antibody positive pigs against an antigenic variant and a heterologous swine influenza virus challenge. Groups of three-week-old commercial-grade pigs were immunized intranasally with PAV or a commercial vaccine (CV) twice at 2 weeks intervals. Three weeks after the second immunization, pigs were challenged with the antigenic variant Swine/MN/08 H1N1 (MN08) and the heterologous Swine/NC/10 H1N2 (NC10) influenza virus. Antibodies in serum and respiratory tract, lung lesions, virus shedding in nasal secretions and virus load in lungs were assessed. Intranasal administration of PAV induced challenge viruses specific-hemagglutination inhibition- and IgG antibodies in the serum and IgA and IgG antibodies in the respiratory tract. Importantly, intranasal administration of PAV provided protection against the antigenic variant MN08 and the heterologous NC10 swine influenza viruses as evidenced by significant reductions in lung virus load, gross lung lesions and significantly reduced shedding of challenge viruses in nasal secretions. These results indicate that Poly I:C or its homologues may be effective as vaccine adjuvants capable of generating cross-protective immunity against antigenic variants/heterologous swine influenza viruses in pigs.

  4. Maternal immune activation produces neonatal excitability defects in offspring hippocampal neurons from pregnant rats treated with poly I:C

    PubMed Central

    Patrich, Eti; Piontkewitz, Yael; Peretz, Asher; Weiner, Ina; Attali, Bernard

    2016-01-01

    Maternal immune activation (MIA) resulting from prenatal exposure to infectious pathogens or inflammatory stimuli is increasingly recognized to play an important etiological role in neuropsychiatric disorders with neurodevelopmental features. MIA in pregnant rodents induced by injection of the synthetic double-stranded RNA, Poly I:C, a mimic of viral infection, leads to a wide spectrum of behavioral abnormalities as well as structural and functional defects in the brain. Previous MIA studies using poly I:C prenatal treatment suggested that neurophysiological alterations occur in the hippocampus. However, these investigations used only juvenile or adult animals. We postulated that MIA-induced alterations could occur earlier at neonatal/early postnatal stages. Here we examined the neurophysiological properties of cultured pyramidal-like hippocampal neurons prepared from neonatal (P0-P2) offspring of pregnant rats injected with poly I:C. Offspring neurons from poly I:C-treated mothers exhibited significantly lower intrinsic excitability and stronger spike frequency adaptation, compared to saline. A similar lower intrinsic excitability was observed in CA1 pyramidal neurons from hippocampal slices of two weeks-old poly I:C offspring. Cultured hippocampal neurons also displayed lower frequency of spontaneous firing, higher charge transfer of IPSCs and larger amplitude of miniature IPSCs. Thus, maternal immune activation leads to strikingly early neurophysiological abnormalities in hippocampal neurons. PMID:26742695

  5. Maternal immune activation produces neonatal excitability defects in offspring hippocampal neurons from pregnant rats treated with poly I:C.

    PubMed

    Patrich, Eti; Piontkewitz, Yael; Peretz, Asher; Weiner, Ina; Attali, Bernard

    2016-01-08

    Maternal immune activation (MIA) resulting from prenatal exposure to infectious pathogens or inflammatory stimuli is increasingly recognized to play an important etiological role in neuropsychiatric disorders with neurodevelopmental features. MIA in pregnant rodents induced by injection of the synthetic double-stranded RNA, Poly I:C, a mimic of viral infection, leads to a wide spectrum of behavioral abnormalities as well as structural and functional defects in the brain. Previous MIA studies using poly I:C prenatal treatment suggested that neurophysiological alterations occur in the hippocampus. However, these investigations used only juvenile or adult animals. We postulated that MIA-induced alterations could occur earlier at neonatal/early postnatal stages. Here we examined the neurophysiological properties of cultured pyramidal-like hippocampal neurons prepared from neonatal (P0-P2) offspring of pregnant rats injected with poly I:C. Offspring neurons from poly I:C-treated mothers exhibited significantly lower intrinsic excitability and stronger spike frequency adaptation, compared to saline. A similar lower intrinsic excitability was observed in CA1 pyramidal neurons from hippocampal slices of two weeks-old poly I:C offspring. Cultured hippocampal neurons also displayed lower frequency of spontaneous firing, higher charge transfer of IPSCs and larger amplitude of miniature IPSCs. Thus, maternal immune activation leads to strikingly early neurophysiological abnormalities in hippocampal neurons.

  6. Microbial degradation of poly(amino acid)s.

    PubMed

    Obst, Martin; Steinbüchel, Alexander

    2004-01-01

    Natural poly(amino acid)s are a group of poly(ionic) molecules (ionomers) with various biological functions and putative technical applications and play, therefore, an important role both in nature and in human life. Because of their biocompatibility and their synthesis from renewable resources, poly(amino acid)s may be employed for many different purposes covering a broad spectrum of medical, pharmaceutical, and personal care applications as well as the domains of agriculture and of environmental applications. Biodegradability is one important advantage of naturally occurring poly(amino acid)s over many synthetic polymers. The intention of this review is to give an overview about the enzyme systems catalyzing the initial steps in poly(amino acid) degradation. The focus is on the naturally occurring poly(amino acid)s cyanophycin, poly(epsilon-L-lysine) and poly(gamma-glutamic acid); but biodegradation of structurally related synthetic polyamides such as poly(aspartic acid) and nylons, which are known from various technical applications, is also included.

  7. Lignin poly(lactic acid) copolymers

    DOEpatents

    Olsson, Johan Vilhelm; Chung, Yi-Lin; Li, Russell Jingxian; Waymouth, Robert; Sattely, Elizabeth; Billington, Sarah; Frank, Curtis W.

    2017-02-14

    Provided herein are graft co-polymers of lignin and poly(lactic acid) (lignin-g-PLA copolymer), thermoset and thermoplastic polymers including them, methods of preparing these polymers, and articles of manufacture including such polymers.

  8. Targeting polyIC to EGFR over-expressing cells using a dsRNA binding protein domain tethered to EGF

    PubMed Central

    Edinger, Nufar; Lebendiker, Mario; Klein, Shoshana; Zigler, Maya; Langut, Yael; Levitzki, Alexander

    2016-01-01

    Selective delivery of drugs to tumor cells can increase potency and reduce toxicity. In this study, we describe a novel recombinant chimeric protein, dsRBEC, which can bind polyIC and deliver it selectively into EGFR over-expressing tumor cells. dsRBEC, comprises the dsRNA binding domain (dsRBD) of human PKR (hPKR), which serves as the polyIC binding moiety, fused to human EGF (hEGF), the targeting moiety. dsRBEC shows high affinity towards EGFR and triggers ligand-induced endocytosis of the receptor, thus leading to the selective internalization of polyIC into EGFR over-expressing tumor cells. The targeted delivery of polyIC by dsRBEC induced cellular apoptosis and the secretion of IFN-β and other pro-inflammatory cytokines. dsRBEC-delivered polyIC is much more potent than naked polyIC and is expected to reduce the toxicity caused by systemic delivery of polyIC. PMID:27598772

  9. Molecular cloning of Japanese eel Anguilla japonica TNF-α and characterization of its expression in response to LPS, poly I:C and Aeromonas hydrophila infection

    NASA Astrophysics Data System (ADS)

    Feng, Jianjun; Guan, Ruizhang; Guo, Songlin; Lin, Peng; Zadlock, Frank

    2014-09-01

    As a potent pleiotropic cytokine, tumor necrosis factor-alpha (TNF-α) plays an important role in innate immune responses. The cDNA sequence and genomic structure of the TNF-α gene ( Aj TNF-α) in the Japanese eel ( Anguilla japonica) were identified and characterized. The full-length AjTNF-α cDNA was 1 546 bp, including a 5'-untranslated region (UTR) of 13 bp, a 3'-UTR of 879 bp and an open reading frame of 654 bp encoding a protein of 218 amino acids. The full-length genomic sequence of AjTNF-α was 2 392 bp and included four exons and three introns. The putative AjTNF-α protein contained TNF family signature motifs, including a protease cleavage site, a transmembrane domain and two conserved cysteine residues. Quantitative real-time reverse transcription PCR analysis revealed AjTNF-α expression in a wide range of tissues, with predominant expression in blood and liver. Lower levels of expression were seen in spleen, gills, kidney, intestine, heart, and skin, with very low levels in muscle. The modulation of AjTNF-α expression after injection of eels with lipopolysaccharide (LPS), the viral mimic, poly I:C, or Aeromonas hydrophila was assessed in blood, liver, and kidney. In blood, TNF-α mRNA levels increased rapidly and then rapidly decreased after stimulation with LPS, poly I:C or A. hydrophila. However, the response to LPS and A. hydrophila peaked at 6 h while for poly I:C the peak was at 12 h. In liver, after injection with A. hydrophila, an up- and down-regulation of AjTNF-α expression occurred twice, peaking at 6 h and 24 h, respectively. No remarkable increase of AjTNF-α expression appeared in liver until 72 h after LPS or poly I:C treatment. In kidney, AjTNF-α expression increased significantly only at 72 h post-stimulation with LPS or A. hydrophila. Our results suggest that AjTNF-α plays an important role in fish in the defense against viral and bacterial infection.

  10. Prophylactic and therapeutic intranasal administration with an immunomodulator, Hiltonol(®) (Poly IC:LC), in a lethal SARS-CoV-infected BALB/c mouse model.

    PubMed

    Kumaki, Yohichi; Salazar, Andres M; Wandersee, Miles K; Barnard, Dale L

    2017-03-01

    Hiltonol(®), (Poly IC:LC), a potent immunomodulator, is a synthetic, double-stranded polyriboinosinic-polyribocytidylic acid (poly IC) stabilized with Poly-L-lysine and carboxymethyl cellulose (LC). Hiltonol(®) was tested for efficacy in a lethal SARS-CoV-infected BALB/c mouse model. Hiltonol(®) at 5, 1, 0.5 or 0.25 mg/kg/day by intranasal (i.n.) route resulted in significant survival benefit when administered at selected times 24 h prior to challenge with a lethal dose of mouse-adapted severe acute respiratory syndrome coronavirus (SARS-CoV). The infected BALB/c mice receiving the Hiltonol(®) treatments were also significantly effective in protecting mice against weight loss due to infection (p < 0.001). Groups of 20 mice were dosed with Hiltonol(®) at 2.5 or 0.75 mg/kg by intranasal instillation 7, 14, and 21 days before virus exposure and a second dose was given 24 h later, prophylactic Hiltonol(®) treatments (2.5 mg/kg/day) were completely protective in preventing death, and in causing significant reduction in lung hemorrhage scores, lung weights and lung virus titers. Hiltonol(®) was also effective as a therapeutic when give up to 8 h post virus exposure; 100% of the-infected mice were protected against death when Hiltonol(®) was administered at 5 mg/kg/day 8 h after infection. Our data suggest that Hiltonol(®) treatment of SARS-CoV infection in mice leads to substantial prophylactic and therapeutic effects and could be used for treatment of other virus disease such as those caused by MERS-CoV a related coronavirus. These properties might be therapeutically advantageous if Hiltonol(®) is considered for possible clinical use.

  11. Effect of toll-like receptor 3 agonist poly I:C on intestinal mucosa and epithelial barrier function in mouse models of acute colitis

    PubMed Central

    Zhao, Hong-Wei; Yue, Yue-Hong; Han, Hua; Chen, Xiu-Li; Lu, Yong-Gang; Zheng, Ji-Min; Hou, Hong-Tao; Lang, Xiao-Meng; He, Li-Li; Hu, Qi-Lu; Dun, Zi-Qian

    2017-01-01

    AIM To investigate potential effects of poly I:C on mucosal injury and epithelial barrier disruption in dextran sulfate sodium (DSS)-induced acute colitis. METHODS Thirty C57BL/6 mice were given either regular drinking water (control group) or 2% (w/v) DSS drinking water (model and poly I:C groups) ad libitum for 7 d. Poly I:C was administrated subcutaneously (20 μg/mouse) 2 h prior to DSS induction in mice of the poly I:C group. Severity of colitis was evaluated by disease activity index, body weight, colon length, histology and myeloperoxidase (MPO) activity, as well as the production of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin 17 (IL-17) and interferon-γ (IFN-γ). Intestinal permeability was analyzed by the fluorescein isothiocyanate labeled-dextran (FITC-D) method. Ultrastructural features of the colon tissue were observed under electron microscopy. Expressions of tight junction (TJ) proteins, including zo-1, occludin and claudin-1, were measured by immunohistochemistry/immunofluorescence, Western blot and real-time quantitative polymerase chain reaction (RT-qPCR). RESULTS DSS caused significant damage to the colon tissue in the model group. Administration of poly I:C dramatically protected against DSS-induced colitis, as demonstrated by less body weight loss, lower disease activity index score, longer colon length, colonic MPO activity, and improved macroscopic and histological scores. It also ameliorated DSS-induced ultrastructural changes of the colon epithelium, as observed under scanning electron microscopy, as well as FITC-D permeability. The mRNA and protein expressions of TJ protein, zo-1, occludin and claudin-1 were also found to be significantly enhanced in the poly I:C group, as determined by immunohistochemistry/immunofluorescence, Western blot and RT-qPCR. By contrast, poly I:C pretreatment markedly reversed the DSS-induced up-regulated expressions of the inflammatory cytokines TNF-α, IL-17 and IFN

  12. Toll-like receptor 3 activation promotes desensitization of histamine response in human gingival fibroblasts: Poly (I:C) induces histamine receptor desensitization in human gingival fibroblasts.

    PubMed

    Gutiérrez-Venegas, Gloria; Rodríguez-Pérez, Citlalli Ekaterina

    2012-01-01

    Viruses are associated with the development of periodontal disease, particularly during periods of suppressed cellular immunity. For this reason, we evaluated the hypothesis that viral components regulate the actions of histamine, an important mediator of immune responses. We assessed the effect of Poly (I:C) on histamine-mediated intracellular calcium mobilization in human gingival fibroblasts. Our results show that histamine induces an increase in intracellular calcium concentrations in a dose-dependent manner. This response was blocked when cells were incubated in the presence of Poly (I:C). In addition, phorbol esters, a diacylglycerol analog, mimics the inhibitory actions of Poly (I:C) in response to histamine. The effect of Poly (I:C) was reversed by Stuarosporine (1 μM), GÖ6983 (7 μM), Bisindolylmaleimide (1 μM) [a protein inhibitor (PKC)], and SB 203580 (3 μM) (a p38-MAPK inhibitor). These findings suggest that Poly (I:C) regulates histamine-induced calcium mobilization through activation of PKC and p38.

  13. The role of NK cell activity in the pathogenesis of poly I:C accelerated and spontaneous diabetes in the diabetes prone BB rat.

    PubMed

    Sobel, D O; Azumi, N; Creswell, K; Holterman, D; Blair, O C; Bellanti, J A; Abbassi, V; Hiserodt, J C

    1995-12-01

    The development of insulin dependent diabetes mellitus (IDDM) and diabetes in the diabetes prone (DP) BB rat animal model of IDDM is thought to be due to an autoimmune process. Natural killer (NK) cells have been implicated but not proven to play a pathogenetic role in BB rats due to the increased NK cell number and activity found in these animals. We have recently reported that poly I:C, an inducer of cytokines and a potent enhancer of NK cell function, accelerates the development of diabetes in DP BB rats and induces diabetes in diabetes resistant (DR) BB rats. Since we have further demonstrated that poly I:C administration to BB rats increases NK cell number and levels of inducers of NK cell activity, interferon-alpha and IL-6 which is described therein, we tested the hypothesis that NK cell activity plays an important role in poly I:C accelerated disease. The role of NK cells in poly I:C accelerated diabetes and spontaneous diabetes was examined by determining whether selective depletion of NK cells using a rat NK cell specific antibody (anti-NKR-P1 antibody) alters the development of diabetes. The treatment of BB rats with anti-NKR-P1 antibody resulted in a significantly lower mean NK cell activity of splenic mononuclear cells than that found in control animals. However, the development of diabetes and degree of insulitis was not significantly different between treatment groups. BB rats administered anti-NKR-P1 antibody with poly I:C had a lower mean splenocyte NK cell activity and lower mean NK cell number within the peripheral blood and inflamed islets than rats administered poly I:C alone. However, anti-NKR-P1 antibody administration did not alter the accelerated development of diabetes or the degree of insulitis in poly I:C treated animals. These data document that NK cells do not play a major role in the pathogenesis of poly I:C accelerated diabetes or spontaneous diabetes in the DP BB rat.

  14. Emotional Contagion is not Altered in Mice Prenatally Exposed to Poly (I:C) on Gestational Day 9

    PubMed Central

    Gonzalez-Liencres, Cristina; Juckel, Georg; Esslinger, Manuela; Wachholz, Simone; Manitz, Marie-Pierre; Brüne, Martin; Friebe, Astrid

    2016-01-01

    Prenatal immune activation has been associated with increased risk of developing schizophrenia. The polyinosinic-polycytidylic acid (Poly(I:C)) mouse model replicates some of the endophenotype characteristic of this disorder but the social deficits observed in schizophrenia patients have not been well studied in this model. Therefore we aimed to investigate social behavior, in particular emotional contagion for pain, in this mouse model. We injected pregnant mouse dams with Poly(I:C) or saline (control) on gestation day 9 (GD9) and we evaluated their offspring in the pre-pulse inhibition (PPI) test at age 50–55 days old to confirm the reliability of our model. Mice were then evaluated in an emotional contagion test immediately followed by the light/dark test to explore post-test anxiety-like behavior at 10 weeks of age. In the emotional contagion test, an observer (prenatally exposed to Poly(I:C) or to saline) witnessed a familiar wild-type (WT) mouse (demonstrator) receiving electric foot shocks. Our results replicate the sensory gating impairments in the Poly(I:C) offspring but we only observed minor group differences in the social tasks. One of the differences we found was that demonstrators deposited fewer feces in the presence of control observers than of observers prenatally exposed to Poly(I:C), which we suggest could be due to the observers’ behavior. We discuss the findings in the context of age, sex and day of prenatal injection, suggesting that Poly(I:C) on GD9 may be a valuable tool to assess other symptoms or symptom clusters of schizophrenia but perhaps not comprising the social domain. PMID:27445729

  15. Combined CpG and poly I:C stimulation of monocytes results in unique signaling activation not observed with the individual ligands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Toll-like receptors (TLRs) bind to components of microbes, activate cellular signal transduction pathways, and stimulate innate immune responses. Previously, we have shown in chicken monocytes that the combination of CpG, the ligand for TLR21 (the chicken equivalent of TLR9), and poly I:C, the liga...

  16. Superabsorbent biphasic system based on poly(lactic acid) and poly(acrylic acid)

    NASA Astrophysics Data System (ADS)

    Sartore, Luciana; Pandini, Stefano; Baldi, Francesco; Bignotti, Fabio

    2016-05-01

    In this research work, biocomposites based on crosslinked particles of poly(acrylic acid), commonly used as superabsorbent polymer (SAP), and poly-L-lactic acid (PLLA) were developed to elucidate the role of the filler (i.e., polymeric crosslinked particles) on the overall physico-mechanical behavior and to obtain superabsorbent thermoplastic products. Samples prepared by melt-blending of components in different ratios showed a biphasic system with a regular distribution of particles, with diameter ranging from 5 to 10 μm, within the PLLA polymeric matrix. The polymeric biphasic system, coded PLASA i.e. superabsorbent poly(lactic acid), showed excellent swelling properties, demonstrating that cross-linked particles retain their superabsorbent ability, as in their free counterparts, even if distributed in a thermoplastic polymeric matrix. The thermal characteristics of the biocomposites evidence enhanced thermal stability in comparison with neat PLLA and also mechanical properties are markedly modified by addition of crosslinked particles which induce regular stiffening effect. Furthermore, in aqueous environments the particles swell and are leached from PLLA matrix generating very high porosity. These new open-pore PLLA foams, produced in absence of organic solvents and chemical foaming agents, with good physico-mechanical properties appear very promising for several applications, for instance in tissue engineering for scaffold production.

  17. Biologic activities of poly (2-azaadenylic acid) and poly (2-azainosinic acid).

    PubMed Central

    De Clercq, E; Huang, G F; Torrence, P F; Fukui, T; Kakiuchi, N; Ikehara, M

    1977-01-01

    Poly (2-azaadenylic acid) [(aza2A)n] and poly(2-azainosinic acid [(aza2I)n], two newly synthesized analogues of (A)n and (I)n, in which CH-2 of the purine ring is replaced by a nitrogen atom, have been evaluated in various biological assay systems. (Aza2A) n formed a complex with (U)n and (br5U)n, and (aza2I)n formed a complex with (C)n and (br5C)n, but these complexes were markedly destabilized relative to the corresponding (A)n or (I)n complexes. The (aza2A)n-and (aza2I)n-derived complexes failed to stimulate the production of interferon in primary rabbit kidney cells and human diploid fibroblasts, under conditions (A)n. (U)n, (I)n. (C)n and (I)n. (br5C)n induced high amounts of interferon. both (aza2A)n and (aza2I)n exerted a marked inhibitory effect on the endogenous RNA directed DNA polymerase (reverse transcriptase) activity associated with murine leukemia virus. They caused a relatively mild inhibition of complement activity in an hemolytic assay system. PMID:73166

  18. Longitudinal acoustic properties of poly(lactic acid) and poly(lactic-co-glycolic acid).

    PubMed

    Parker, N G; Mather, M L; Morgan, S P; Povey, M J W

    2010-10-01

    Acoustics offers rich possibilities for characterizing and monitoring the biopolymer structures being employed in the field of biomedical engineering. Here we explore the rudimentary acoustic properties of two common biodegradable polymers: poly(lactic acid) and poly(lactic-co-glycolic acid). A pulse-echo technique is developed to reveal the bulk speed of sound, acoustic impedance and acoustic attenuation of small samples of the polymer across a pertinent temperature range of 0-70 °C. The glass transition appears markedly as both a discontinuity in the first derivative of the speed of sound and a sharp increase in the acoustic attenuation. We further extend our analysis to consider the role of ethanol, whose presence is observed to dramatically modify the acoustic properties and reduce the glass transition temperature of the polymers. Our results highlight the sensitivity of acoustic properties to a range of bulk properties, including visco-elasticity, molecular weight, co-polymer ratio, crystallinity and the presence of plasticizers.

  19. Poly(lactic acid) and poly(lactic-co-glycolic acid) particles as versatile carrier platforms for vaccine delivery.

    PubMed

    Pavot, Vincent; Berthet, Morgane; Rességuier, Julien; Legaz, Sophie; Handké, Nadège; Gilbert, Sarah C; Paul, Stéphane; Verrier, Bernard

    2014-12-01

    The development of safe and effective vaccines for cancer and infectious diseases remains a major goal in public health. Over the last two decades, controlled release of vaccine antigens and immunostimulant molecules has been achieved using nanometer or micron-sized delivery vehicles synthesized using biodegradable polymers. In addition to achieving a depot effect, enhanced vaccine efficacy using such delivery vehicles has been attributed to efficient targeting of antigen presenting cells such as dendritic cells. Biodegradable and biocompatible poly(lactic acid) and poly(lactic-co-glycolic acid) polymers belong to one such family of polymers that have been a popular choice of material used in the design of these delivery vehicles. This review summarizes research findings from ourselves and others highlighting the promise of poly(lactic acid)- and poly(lactic-co-glycolic acid)-based vaccine carriers in enhancing immune responses.

  20. Zwitterionic Poly(amino acid methacrylate) Brushes

    PubMed Central

    2014-01-01

    A new cysteine-based methacrylic monomer (CysMA) was conveniently synthesized via selective thia-Michael addition of a commercially available methacrylate-acrylate precursor in aqueous solution without recourse to protecting group chemistry. Poly(cysteine methacrylate) (PCysMA) brushes were grown from the surface of silicon wafers by atom-transfer radical polymerization. Brush thicknesses of ca. 27 nm were achieved within 270 min at 20 °C. Each CysMA residue comprises a primary amine and a carboxylic acid. Surface zeta potential and atomic force microscopy (AFM) studies of the pH-responsive PCysMA brushes confirm that they are highly extended either below pH 2 or above pH 9.5, since they possess either cationic or anionic character, respectively. At intermediate pH, PCysMA brushes are zwitterionic. At physiological pH, they exhibit excellent resistance to biofouling and negligible cytotoxicity. PCysMA brushes undergo photodegradation: AFM topographical imaging indicates significant mass loss from the brush layer, while XPS studies confirm that exposure to UV radiation produces surface aldehyde sites that can be subsequently derivatized with amines. UV exposure using a photomask yielded sharp, well-defined micropatterned PCysMA brushes functionalized with aldehyde groups that enable conjugation to green fluorescent protein (GFP). Nanopatterned PCysMA brushes were obtained using interference lithography, and confocal microscopy again confirmed the selective conjugation of GFP. Finally, PCysMA undergoes complex base-catalyzed degradation in alkaline solution, leading to the elimination of several small molecules. However, good long-term chemical stability was observed when PCysMA brushes were immersed in aqueous solution at physiological pH. PMID:24884533

  1. Production of Poly-β-Hydroxyalkanoic Acid by Pseudomonas cepacia

    PubMed Central

    Ramsay, Bruce A.; Ramsay, Juliana A.; Cooper, David G.

    1989-01-01

    The possibility of using the nutritionally versatile bacterium Pseudomonas cepacia to produce poly-β-hydroxyalkanoic acid was evaluated. Chemostat culture showed that growth of P. cepacia became nitrogen limited when the molar carbon-to-nitrogen ratio of the medium fed into the fermentor was above 15. When grown under nitrogen limitation in batch culture with fructose as the sole source of carbon, P. cepacia accumulated poly-β-hydroxybutyric acid (PHB) in excess of 50% of the dry weight of its biomass. In batch culture, almost no PHB was produced until the onset of nitrogen limitation. After this point, PHB was produced at a linear rate of 0.12 g liter−1 h−1 (from a constant value of 1.6 g of cellular protein liter−1). PHB produced by P. cepacia had a weight-average molecular weight of 5.37 × 105 g mol−1 and a polydispersivity index of 3.9. Poly(β-hydroxybutyric acid-β-hydroxyvaleric acid) copolymer was produced with a poly-β-hydroxybutyric acid-poly-β-hydroxyvaleric acid ratio of up to 30% by weight when propionic acid was added to the medium. PMID:16347867

  2. Poly (I:C) enhances the anti-tumor activity of canine parvovirus NS1 protein by inducing a potent anti-tumor immune response.

    PubMed

    Gupta, Shishir Kumar; Yadav, Pavan Kumar; Tiwari, A K; Gandham, Ravi Kumar; Sahoo, A P

    2016-09-01

    The canine parvovirus NS1 (CPV2.NS1) protein selectively induces apoptosis in the malignant cells. However, for an effective in vivo tumor treatment strategy, an oncolytic agent also needs to induce a potent anti-tumor immune response. In the present study, we used poly (I:C), a TLR3 ligand, as an adjuvant along with CPV2.NS1 to find out if the combination can enhance the oncolytic activity by inducing a potent anti-tumor immune response. The 4T1 mammary carcinoma cells were used to induce mammary tumor in Balb/c mice. The results suggested that poly (I:C), when given along with CPV2.NS1, not only significantly reduced the tumor growth but also augmented the immune response against tumor antigen(s) as indicated by the increase in blood CD4+ and CD8+ counts and infiltration of immune cells in the tumor tissue. Further, blood serum analysis of the cytokines revealed that Th1 cytokines (IFN-γ and IL-2) were significantly upregulated in the treatment group indicating activation of cell-mediated immune response. The present study reports the efficacy of CPV2.NS1 along with poly (I:C) not only in inhibiting the mammary tumor growth but also in generating an active anti-tumor immune response without any visible toxicity. The results of our study may help in developing CPV2.NS1 and poly (I: C) combination as a cancer therapeutic regime to treat various malignancies.

  3. Inhibition of Poly(ADP-Ribose) Polymerase by Nucleic Acid Metabolite 7-Methylguanine

    PubMed Central

    Nilov, D. K.; Tararov, V. I.; Kulikov, A. V.; Zakharenko, A. L.; Gushchina, I. V.; Mikhailov, S. N.; Lavrik, O. I.; Švedas, V. K.

    2016-01-01

    The ability of 7-methylguanine, a nucleic acid metabolite, to inhibit poly(ADP-ribose)polymerase-1 (PARP-1) and poly(ADP-ribose)polymerase-2 (PARP-2) has been identified in silico and studied experimentally. The amino group at position 2 and the methyl group at position 7 were shown to be important substituents for the efficient binding of purine derivatives to PARPs. The activity of both tested enzymes, PARP-1 and PARP-2, was suppressed by 7-methylguanine with IC50 values of 150 and 50 μM, respectively. At the PARP inhibitory concentration, 7-methylguanine itself was not cytotoxic, but it was able to accelerate apoptotic death of BRCA1-deficient breast cancer cells induced by cisplatin and doxorubicin, the widely used DNA-damaging chemotherapeutic agents. 7-Methylguanine possesses attractive predictable pharmacokinetics and an adverse-effect profile and may be considered as a new additive to chemotherapeutic treatment. PMID:27437145

  4. Estimation of the poly (ε-caprolactone) [PCL] and α-cyclodextrin [α-CD] stoichiometric ratios in their inclusion complexes [ICs], and evaluation of porosity and fiber alignment in PCL nanofibers containing these ICs.

    PubMed

    Narayanan, Ganesh; Gupta, Bhupender S; Tonelli, Alan E

    2015-12-01

    This paper describes the utilization of Proton-Nuclear Magnetic Resonance spectroscopy ((1)H NMR) to quantify the stoichiometric ratios between poly (ε-caprolactone) [PCL] and α-cyclodextrin (α-CD) present in their non-stoichiometric inclusion complexes [(n-s)-ICs]. This paper further describes the porosity and fiber alignment of PCL nanofibers nucleated by the [(n-s)-ICs] during electrospinning. (1)H NMR indicated that the two non-stoichiometric inclusion complexes utilized in this study had differing stoichiometric ratios that were closely similar to those of the starting ratios used to make them. Studies on porosity and fiber alignments were conducted on the scanning electron microscope images using ImageJ. The data indicates that both fiber alignment as well as porosity values remain almost the same over all the samples. Thus we can conclude the improvement in mechanical properties was due only to the loading of the ICs, and their subsequent interaction with bulk unthreaded PCL.

  5. The determination of haloacetic acids in real world samples using IC-ESI-MS-MS.

    PubMed

    Slingsby, Rosanne; Saini, Charanjit; Pohl, Christopher

    2009-08-01

    This paper presents the determination of nine haloacetic acids (HAAs) in high ionic strength, treated effluent waters using an ion chromatography-electrospray ionization-tandem mass spectrometry (IC-ESI-MS-MS) method with internal standards and discussions of each of the method parameters. Data is also provided for these same samples using USEPA Method 552.2. The sample matrices contain up to 170 mg/L chloride and 243 mg/L sulfate. Matrix ions are separated from the analytes using a high capacity anion exchange analytical column and diverted to a waste stream during each analysis to avoid signal suppression and contamination of the detector. No derivatization, offline matrix elimination, or preconcentration is used. Four isotopically-labeled HAAs are used for quantification, and detection limits are in the range of 400-1000 microg/L with R(2) of at least 0.997 over two orders of magnitude for all analytes in matrix. A trichloroacetic acid (TCAA) internal standard with the label on the alpha carbon is found to be more stable than the TCAA-1-(13)C. Amounts found using IC-MS-MS are 65-130% of amounts found using Method 552.2 for all analytes in the real world treated effluent waters. Detection limits for all nine analytes in matrix are in the range of 100-700 ng/L.

  6. New nucleic acid triple helix, Poly(AAU)

    SciTech Connect

    Broitman, S.L.; Im, D.D.; Fresco, J.R.

    1987-05-01

    A polynucleotide helical structure containing two strands of poly(A) and one of poly(U) has been discovered. The stoichiometry of the complex was determined by continuous variation titrations and isosbestic wavelength analysis. Thermal denaturation profiles were used to examine complex stability over a wide range of conditions. The complex forms only when the poly(A) strands are of molecular weight between 9000-50,000 Daltons (dp approx. 28-150), whereas the size of the poly(U) strand has no effect. This limitation may explain why poly(AAU) was not observed in previous investigations. The complex shows inverse dependence of stability on ionic strength, but is not favored by decreasing pH. This behavior, together with the intermediate poly(A) size requirement suggest that the conformational entropy of the poly(A) strands is a critical determinant of the stability of this complex. The potential of the poly(A) tails of mRNA for formation of this triple helix, and of AAU/T triplet formation to contribute to the binding of unique sequence RNA strands to gene-encoding nucleic acid double helices are noted.

  7. Platinum-Incorporating Poly(N-vinylpyrrolidone)-poly(aspartic acid) Pseudoblock Copolymer Nanoparticles for Drug Delivery.

    PubMed

    Yao, Xikuang; Xie, Chen; Chen, Weizhi; Yang, Chenchen; Wu, Wei; Jiang, Xiqun

    2015-07-13

    Cisplatin-incorporating pseudoblock copolymer nanoparticles with high drug loading efficiency (ca. 50%) were prepared built on host-guest inclusion complexation between β-cyclodextrin end-capped poly(N-vinylpyrrolidone) block and admantyl end-capped poly(aspartic acid) block, followed by the coordination between cisplatin and carboxyl groups in poly(aspartic acid). The host-guest interaction between the two polymer blocks was examined by two-dimensional nuclear overhauser effect spectroscopy. The size and morphology of nanoparticles formed were characterized by dynamic light scattering, zeta potential, transmission electron microscopy, and atomic force microscopy. The size control of nanoparticles was carried out by varying the ratio of poly(N-vinylpyrrolidone) to poly(aspartic acid). The nanoparticles were stable in the aqueous medium with different pH values but disintegrated in the medium containing Cl(-) ions. The in vitro and in vivo antitumor effects of cisplatin-loaded nanoparticles were evaluated. The biodistribution of the nanoparticles in vivo was studied by noninvasive near-infrared fluorescence imaging and ion-coupled plasma mass spectrometry. It was found that cisplatin-loaded nanoparticles could effectively accumulate in the tumor site and exhibited significant superior in vivo antitumor activity to the commercially available free cisplatin by combining the tumor volume, body weight, and survival rate measurements.

  8. Miscibility and Morphology of Poly(lactic ACID)/POLY(Β-HYDROXYBUTYRATE) Blends

    NASA Astrophysics Data System (ADS)

    Tri Phuong, Nguyen; Guinault, Alain; Sollogoub, Cyrille

    2011-01-01

    The miscibility and morphology of poly(lactic)acid (PLA)/polyβ-hydroxybutyrate (PHB) prepared by melt blending method were investigated by Fourier transform infrared (FTIR), Differential scanning calorimetry (DSC), melt rheology and scanning electron microscopy (SEM) observations. FTIR and DSC methods present some limits to examine the miscibility state of PLA/PHB blends. This drawback can be overcome with the Cole-Cole method by observing the η" = f(η') curves to confirm the miscibility of semicrystalline PLA/ semicrystalline PHB blends. MEB micrographs of fractured surface of blends were also used to investigate the miscibility of these blends.

  9. Interactions of sodium montmorillonite with poly(acrylic acid).

    PubMed

    Tran, Nguyen H; Dennis, Gary R; Milev, Adriyan S; Kannangara, G S Kamali; Wilson, Michael A; Lamb, Robert N

    2005-10-15

    The chemical-structural modifications of the natural clay sodium montmorillonite during interaction with poly(acrylic acid) were studied mainly by X-ray photoemission spectroscopy. Samples of modified montmorillonite were prepared from the reaction of sodium montmorillonite ( approximately 0.5 g) and an aqueous solution of poly(acrylic acid) (pH approximately 1.8, 50 g) at varying temperatures. X-ray diffraction indicated that the montmorillonite interlayer space ( approximately 13 A), formed by regular stacking of the silicate layers (dimension approximately 1x1000 nm), expanded to approximately 16 A as the reaction was carried out at room temperature and at 30 degrees C. At 60 degrees C, the interlayer space further expanded to approximately 20 A. The results of X-ray photoemission spectroscopy indicated that poly(acrylic acid) molecules exchange sodium ions on the surface of the silicate layers. These combined results allowed development of a reaction model that explains the dependency of the interlayer expansion with temperature. Information concerning the surface chemical reactions and systematic increases in the interlayer distances is particularly useful if montmorillonite and poly(acrylic acid) are to be used for formation of nanocomposite materials.

  10. Thermal properties of poly (lactic acid)/milkweed composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Currently, most polymer composites utilize petroleum-based materials that are non-degradable and difficult to recycle or incur substantial cost for disposal. Green composites can be used in nondurable limited applications. In order to determine the degree of compatibility between Poly (lactic Acid...

  11. GAS PERMEATION PROPERTIES OF POLY(LACTIC ACID). (R826733)

    EPA Science Inventory

    Abstract

    The need for the development of polymeric materials based on renewable resources has led to the development of poly(lactic acid) (PLA) which is being produced from a feedstock of corn rather than petroleum. The present study examines the permeation of nitrogen...

  12. Antimicrobial activity of poly(acrylic acid) block copolymers.

    PubMed

    Gratzl, Günther; Paulik, Christian; Hild, Sabine; Guggenbichler, Josef P; Lackner, Maximilian

    2014-05-01

    The increasing number of antibiotic-resistant bacterial strains has developed into a major health problem. In particular, biofilms are the main reason for hospital-acquired infections and diseases. Once formed, biofilms are difficult to remove as they have specific defense mechanisms against antimicrobial agents. Antimicrobial surfaces must therefore kill or repel bacteria before they can settle to form a biofilm. In this study, we describe that poly(acrylic acid) (PAA) containing diblock copolymers can kill bacteria and prevent from biofilm formation. The PAA diblock copolymers with poly(styrene) and poly(methyl methacrylate) were synthesized via anionic polymerization of tert-butyl acrylate with styrene or methyl methacrylate and subsequent acid-catalyzed hydrolysis of the tert-butyl ester. The copolymers were characterized via nuclear magnetic resonance spectroscopy (NMR), size-exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FTIR), elemental analysis, and acid-base titrations. Copolymer films with a variety of acrylic acid contents were produced by solvent casting, characterized by atomic force microscopy (AFM) and tested for their antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The antimicrobial activity of the acidic diblock copolymers increased with increasing acrylic acid content, independent of the copolymer-partner, the chain length and the nanostructure.

  13. ANTIGENICITY OF POLYPEPTIDES (POLY ALPHA AMINO ACIDS)

    PubMed Central

    Pinchuck, Paul; Maurer, Paul H.

    1965-01-01

    The response of mice to synthetic linear polypeptides of known composition but random sequence has been studied. Neither Swiss mice nor a number of inbred strains could respond to copolymers of only 2 amino acids (G60L40, G60A40, G90T10). Upon introduction of as little as 4 mole per cent of a third amino acid, good immune responses were obtained, regardless of the nature of the third amino acid. The level of the immune response to a series of glu-lys-ala polymers increased with increasing alanine content of the polymer. PMID:5849232

  14. Polymers with complexing properties. Simple poly(amino acids)

    NASA Technical Reports Server (NTRS)

    Roque, J. M.

    1978-01-01

    The free amino (0.3 equiv/residue) and carboxyl (0.5 equiv/residue) groups of thermal polylysine increased dramatically on treatment with distilled water. The total hydrolysis of such a polymer was abnormal in that only about 50% of the expected amino acids were recovered. Poly (lysine-co-alanine-co-glycine) under usual conditions hydrolyzed completely in 8 hours; whereas, when it was pretreated with diazomethane, a normal period of 24 hours was required to give (nearly) the same amounts of each free amino acid as compared with those obtained from the untreated polymer. The amino groups of the basic thermal poly(amino acids) were sterically hindered. The existence of nitrogen atoms linking two or three chains and reactive groups (anhydride, imine) were proposed.

  15. Poly(amino acid) functionalized maghemite and gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Perego, Davide; Masciocchi, Norberto; Guagliardi, Antonietta; Domínguez-Vera, José Manuel; Gálvez, Natividad

    2013-02-01

    Bimodal MRI/OI imaging probes are of great interest in nanomedicine. Although many organic polymers have been studied thoroughly for in vivo applications, reports on the use of poly(amino acid)s as coating polymers are scarce. In this paper, poly-(d-glutamic acid, d-lysine) (PGL) has been used for coating maghemite and gold nanoparticles. An advantage of this flexible and biocompatible polymer is that, once anchored to the nanoparticle surface, dangling lysine amino groups are available for the incorporation of new functionalities. As an example, Alexa Fluor derivatives have been attached to PGL-coated maghemite nanoparticles to obtain magnetic/fluorescent materials. These dual-property materials could be used as bimodal MRI/OI probes for in vivo imaging.

  16. Production of poly-(beta-hydroxybutyric-co-beta-hydroxyvaleric) acids.

    PubMed Central

    Ramsay, B A; Lomaliza, K; Chavarie, C; Dubé, B; Bataille, P; Ramsay, J A

    1990-01-01

    Alcaligenes latus, Alcaligenes eutrophus, Bacillus cereus, Pseudomonas pseudoflava, Pseudomonas cepacia, and Micrococcus halodenitrificans were found to accumulate poly-(beta-hydroxybutyric-co-beta-hydroxyvaleric) acid [P(HB-co-HV)] copolymer when supplied with glucose (or sucrose in the case of A. latus) and propionic acid under nitrogen-limited conditions. A fed-batch culture of A. eutrophus produced 24 g of poly-beta-hydroxybutyric acid (PHB) liter-1 under ammonium limitation conditions. When the glucose feed was replaced with glucose and propionic acid during the polymer accumulation phase, 17 g of P(HB-co-HV) liter-1 was produced. The P(HB-co-HV) contained 5.0 mol% beta-hydroxyvaleric acid (HV). Varying the carbon-to-nitrogen ratio at a dilution rate of 0.15 h-1 in a chemostat culture of A. eutrophus resulted in a maximum value of 33% (wt/wt) PHB in the biomass. In comparison, A. latus accumulated about 40% (wt/wt) PHB in chemostat culture under nitrogen-limited conditions at the same dilution rate. When propionic acid was added to the first stage of a two-stage chemostat, A. latus produced 43% (wt/wt) P(HB-co-HV) containing 18.5 mol% HV. In the second stage, the P(HB-co-HV) increased to 58% (wt/wt) with an HV content of 11 mol% without further addition of carbon substrate. The HV composition in P(HB-co-HV) was controlled by regulating the concentration of propionic acid in the feed. Poly-beta-hydroxyalkanoates containing a higher percentage of HV were produced when pentanoic acid replaced propionic acid. PMID:2117877

  17. ANTIGENICITY OF POLYPEPTIDES (POLY ALPHA AMINO ACIDS)

    PubMed Central

    Maurer, Paul H.; Gerulat, Bernard F.; Pinchuck, Paul

    1964-01-01

    A new group of synthetic random polymers of α-L-amino acids has been studied for immunogenicity. With the glutamic acid and alanine copolymers, those consisting of almost equimolar amounts of the two (G60A40 and G40A60) were effective antigens in rabbits whereas those with higher glutamic acid contents (G75A25, G90A10) were poor antigens. The substitution of alanine by valine or leucine (G75V25 and G80Leu20) produced copolymers which were poor antigens in rabbits but effective in guinea pigs. L70A30, although capable of "non-specifically" precipitating serum proteins, was shown not to be antigenic in either rabbits or guinea pigs. The introduction of alanine into glutamic acid and lysine polymers (GLA series) enhanced the immunogenicity of the terpolymers, i.e., GLA30 > GLA20 > GLA10 > GL. The mechanism by which this may be accomplished is discussed as possibly being related to the reduction of the interactions between glutamyl and lysyl residues which allows the carboxyl groups to act as strong immunogenic determinants. PMID:14176288

  18. Interdependent and independent roles of type I interferons and IL-6 in innate immune, neuroinflammatory and sickness behaviour responses to systemic poly I:C

    PubMed Central

    Murray, Carol; Griffin, Éadaoin W.; O’Loughlin, Elaine; Lyons, Aoife; Sherwin, Eoin; Ahmed, Suaad; Stevenson, Nigel J; Harkin, Andrew; Cunningham, Colm

    2015-01-01

    Type I interferons (IFN-I) are expressed in the brain during many inflammatory and neurodegenerative conditions and have multiple effects on CNS function. IFN-I is readily induced in the brain by systemic administration of the viral mimetic, poly I:C (synthetic double-stranded RNA). We hypothesised that IFN-I contributes to systemically administered poly I:C-induced sickness behaviour, metabolic and neuroinflammatory changes. IFN-I receptor 1 deficient mice (IFNAR1−/−) displayed significantly attenuated poly I:C-induced hypothermia, hypoactivity and weight loss compared to WT C57BL/6 mice. This amelioration of sickness was associated with equivalent IL-1β and TNF-α responses but much reduced IL-6 responses in plasma, hypothalamus and hippocampus of IFNAR1−/− mice. IFN-β injection induced trivial IL-6 production and limited behavioural change and the poly I:C-induced IFN-β response did not preceed, and would not appear to mediate, IL-6 induction. Rather, IFNAR1−/− mice lack basal IFN-I activity, have lower STAT1 levels and show significantly lower levels of several inflammatory transcripts, including stat1. Basal IFN-I activity appears to play a facilitatory role in the full expression of the IL-6 response and activation of the tryptophan-kynurenine metabolism pathway. The deficient IL-6 response in IFNAR1−/− mice partially explains the observed incomplete sickness behaviour response. Reconstitution of circulating IL-6 revealed that the role of IFNAR in burrowing activity is mediated via IL-6, while IFN-I and IL-6 have additive effects on hypoactivity, but the role of IFN-I in anorexia is independent of IL-6. Hence, we have demonstrated both interdependent and independent roles for IFN-I and IL-6 in systemic inflammation-induced changes in brain function. PMID:25900439

  19. Poly I:C induces a protective antiviral immune response in the Pacific oyster (Crassostrea gigas) against subsequent challenge with Ostreid herpesvirus (OsHV-1 μvar).

    PubMed

    Green, Timothy J; Montagnani, Caroline

    2013-08-01

    In-vivo studies were carried out to investigate the protective effect of a synthetic viral analogue (poly I:C) against Ostreid herpes virus (OsHV-1 μvar). Pacific oysters (Crassostrea gigas) were immune-primed by intramuscular injection of 240 μg of poly I:C or sterile seawater at 1 day prior to infection with OsHV-1 μvar. Poly I:C injection induced an antiviral state in C. gigas as the percentage of viral-infected oysters at 48 h post infection was significantly lower in the poly I:C treatment (11%) compared to seawater controls (100%). In an additional experiment, we demonstrated that the protective role of poly I:C is reproducible and elicits a specific antiviral response as immune-priming with heat-killed Vibrio splendidus provided no protection against subsequent viral infection. In both experiments, genes homologous to a toll-like receptor (TLR), MyD88, interferon regulatory factor (IRF) and protein kinase R (PKR) were up-regulated in oysters immune-primed with poly I:C compared to seawater controls (p < 0.05). The MyD88, IRF and PKR genes were also significantly up-regulated in response to OsHV-1 μvar infection (p < 0.05), which is suggestive that they are implicated in the antiviral response of C. gigas. Our results demonstrate that C. gigas can recognise double-strand RNA to initiate an innate immune response that inhibits viral infection. The observed response has striking similarities to the hallmarks of the type-1 interferon response of vertebrates.

  20. Enhanced Osteoblast Functions on Nanophase Titania in Poly-lactic-co-glycolic Acid (PLGA) Composites

    DTIC Science & Technology

    2005-01-01

    Poly - lactic -co-glycolic Acid (PLGA) Composites Huinan Liu’, Elliott B. Slamovich’ and Thomas J. Webster’ 2 1School of Materials Engineering, 501...collagen matrix. For this purpose, poly - lactic -co- glycolic acid (PLGA) was dissolved in chloroform and nanometer grain size titania was dispersed by...gelatin, fibrin or collagen [4-6]), synthetic bioresorbable polymers (e.g., polylactic acid , polyglycolic acid and poly - lactic -co-glycolic acid [7-9

  1. Direct Type I IFN but Not MDA5/TLR3 Activation of Dendritic Cells Is Required for Maturation and Metabolic Shift to Glycolysis after Poly IC Stimulation

    PubMed Central

    Haddad, Elias; Wood, Elizabeth G.; Longhi, M. Paula

    2014-01-01

    Type I interferons (IFNs) play an important role in direct antiviral defense as well as linking the innate and adaptive immune responses. On dendritic cells (DCs), IFNs facilitate their activation and contribute to CD8+ and CD4+ T cell priming. However, the precise molecular mechanism by which IFNs regulate maturation and immunogenicity of DCs in vivo has not been studied in depth. Here we show that, after in vivo stimulation with the TLR ligand poly IC, IFNs dominate transcriptional changes in DCs. In contrast to direct TLR3/mda5 signaling, IFNs are required for upregulation of all pathways associated with DC immunogenicity. In addition, metabolic pathways, particularly the switch from oxidative phosphorylation to glycolysis, are also regulated by IFNs and required for DC maturation. These data provide evidence for a metabolic reprogramming concomitant with DC maturation and offer a novel mechanism by which IFNs modulate DC maturation. PMID:24409099

  2. Properties of electrospun pollock gelatin/poly(vinyl alcohol) and pollock gelatin/poly(lactic acid) fibers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pollock gelatin/poly(vinyl alcohol) (PVA) fibers were electrospun using deionized water as the solvent and pollock gelatin/poly(lactic acid) (PLA) fibers were electrospun using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the solvent. The chemical, thermal, and thermal stability properties were exami...

  3. Poly(lactic acid) degradable plastics, coatings, and binders

    SciTech Connect

    Bonsignore, P.V.; Coleman, R.D.; Mudde, J.P.

    1992-05-01

    Biochemical processes to derive value from the management of high carbohydrate food wastes, such as potato starch, corn starch, and cheese whey permeate, have typically been limited to the production of either ethanol or methane. Argonne National Laboratory (ANL) believes that lactic acid presents an attractive option for an alternate fermentation end product, especially in light of lactic acids` being a viable candidate for conversion to environmentally safe poly(lactic acid) (PLA) degradable plastics, coatings, and binders. Technology is being developed at ANL to permit a more cost effective route to modified high molecular weight PLA. Preliminary data on the degradation behavior of these modified PLAs shows the retention to the inherent hydrolytic degradability of the PLA modified, however, by introduced compositional variables. A limited study was done on the hydrolytic stability of soluble oligomers of poly(L-lactic acid). Over a 34 day hold period, water-methanol solutions of Pl-LA oligomers in the 2-10 DP range retained some 75% of their original molecular weight.

  4. Poly(lactic acid) degradable plastics, coatings, and binders

    SciTech Connect

    Bonsignore, P.V.; Coleman, R.D.; Mudde, J.P.

    1992-01-01

    Biochemical processes to derive value from the management of high carbohydrate food wastes, such as potato starch, corn starch, and cheese whey permeate, have typically been limited to the production of either ethanol or methane. Argonne National Laboratory (ANL) believes that lactic acid presents an attractive option for an alternate fermentation end product, especially in light of lactic acids' being a viable candidate for conversion to environmentally safe poly(lactic acid) (PLA) degradable plastics, coatings, and binders. Technology is being developed at ANL to permit a more cost effective route to modified high molecular weight PLA. Preliminary data on the degradation behavior of these modified PLAs shows the retention to the inherent hydrolytic degradability of the PLA modified, however, by introduced compositional variables. A limited study was done on the hydrolytic stability of soluble oligomers of poly(L-lactic acid). Over a 34 day hold period, water-methanol solutions of Pl-LA oligomers in the 2-10 DP range retained some 75% of their original molecular weight.

  5. Degradation and compatibility behaviors of poly(glycolic acid) grafted chitosan.

    PubMed

    Zhang, Luzhong; Dou, Sufeng; Li, Yan; Yuan, Ying; Ji, Yawei; Wang, Yaling; Yang, Yumin

    2013-07-01

    The films of poly(glycolic acid) grafted chitosan were prepared without using a catalyst to improve the degradable property of chitosan. The films were characterized by Fourier transform-infrared spectroscopy and X-ray photoelectron spectroscopy (XPS). The degradation of the poly(glycolic acid) grafted chitosan films were investigated in the lysozyme solution. In vitro degradation tests revealed that the degradation rate of poly(glycolic acid) grafted chitosan films increased dramatically compared with chitosan. The degradation rate of poly(glycolic acid) grafted chitosan films gradually increased with the increasing of the molar ratio of glycolic acid to chitosan. Additionally, the poly(glycolic acid) grafted chitosan films have good biocompatibility, as demonstrated by in vitro cytotoxicity of the extraction fluids. The biocompatible and biodegradable poly(glycolic acid) grafted chitosan would be an effective material with controllable degradation rate to meet the diverse needs in biomedical fields.

  6. Comparative efficacy of virus like particle (VLP) vaccine of foot-and-mouth-disease virus (FMDV) type O adjuvanted with poly I:C or CpG in guinea pigs.

    PubMed

    Terhuja, Megolhubino; Saravanan, Paramasivam; Tamilselvan, Ramasamy Periyasamy

    2015-11-01

    Foot-and-mouth disease (FMD) is one of the most contagious and economically important diseases of cloven-hoofed livestock. Currently used inactivated FMD vaccines have short lived immunity besides risk of handling live virus. We studied recombinant FMD virus like particles (VLPs) encoded by FMDV type O/IND/R2/75 polyprotein genes expressed in Sf9 cells and adjuvanted with CpG or Poly I:C in inducing protective immune response in guinea pigs. Guinea pigs immunized with VLP + CpG vaccine had shown markedly higher cell mediated immunity (CMI) in comparison to the conventional vaccine group as evident from higher levels of IgG2 than IgG1. Although the humoral response was less in VLP + CpG compared to conventional vaccine, the lymphocyte stimulation index was more in VLP + CpG compared to conventional and VLP + Poly I:C vaccine groups. Finally the challenge experiments on 28 and 56 dpv had shown 75% protection in VLP + CpG immunized guinea pigs primary and boosted animals, while 50% and 62% protection in VLP + Poly I:C in primary and boosted animals, respectively. In conclusion, CpG adjuvant was found to be superior followed by ISA206 and Poly I:C in eliciting protection in VLP based FMD vaccines in guinea pigs.

  7. Evaluation of the Protective Efficacy of Poly I:C as an Adjuvant for H9N2 Subtype Avian Influenza Inactivated Vaccine and Its Mechanism of Action in Ducks

    PubMed Central

    Zhang, Aiguo; Lai, Hanzhang; Xu, Jiahua; Huang, Wenke; Liu, Yufu; Zhao, Dawei; Chen, Ruiai

    2017-01-01

    Current commercial H9 avian influenza vaccines cannot provide satisfactory protective immunity against antigenic variant influenza viruses in ducks. Poly I:C, when used as an adjuvant, improves humoral and cellular immunity in many animals but has not been tested in ducks. In this study, we investigated the protective efficacy of Poly I:C as an adjuvant for an inactivated H9N2 Avian influenza vaccine in ducks. We found that an H9N2 vaccine administered with poly I:C (H9-PIC vaccine) induced a significantly more rapid response with higher anti-influenza antibody titers than those of the vaccine alone (H9 vaccine). Moreover, virus shedding was reduced in ducks immunized with the H9-PIC vaccine after challenge with an H9 subtype antigenic variant viruses. IFN-α, IFN-γ, IL-6 and MHC-II mRNA levels were all elevated in ducks receiving the H9-PIC vaccine. In addition, lower expression level of MHC-I may be a reason for inefficient protective ability against heterologous influenza viruses in H9-PIC vaccination of ducks. In conclusion, poly I:C adjuvant enhanced both humoral and cellular immune responses in ducks induced by immunization of inactivated H9N2 vaccine. PMID:28135294

  8. Cyclic RGD conjugated poly(ethylene glycol)-co-poly(lactic acid) micelle enhances paclitaxel anti-glioblastoma effect.

    PubMed

    Zhan, Changyou; Gu, Bing; Xie, Cao; Li, Jin; Liu, Yu; Lu, Weiyue

    2010-04-02

    The use of glioblastoma-targeted drug delivery system facilitates efficient delivery of chemotherapeutic agents to malignant gliomas in the central nervous system while minimizing high systemic doses associated with debilitating toxicities. To employ the high binding affinity of a cyclic RGD peptide (c(RGDyK), cyclic Arginine-Glycine-Aspartic acid-D-Tyrosine-Lysine) with integrin alpha(v)beta(3) over-expressed on tumor neovasculature and U87MG glioblastoma cells, we prepared paclitaxel-loaded c(RGDyK)-Poly(ethylene glycol)-block-poly(lactic acid) micelle (c(RGDyK)-PEG-PLA-PTX). In vitro physicochemical characterization of these novel micelles showed satisfactory encapsulated efficiency, loading capacity and size distribution. In vitro cytotoxicity studies proved that the presence of c(RGDyK) enhanced the anti-glioblastoma cell cytotoxic efficacy by 2.5 folds. The binding affinity of c(RGDyK)-PEG-PLA micelle with U87MG cells was also investigated. The competitive binding IC(50) value of c(RGDyK)-PEG-PLA micelle was 26.30 nM, even lower than that of c(RGDyK) (56.23 nM). In U87MG glioblastoma-bearing nude mice model, biodistribution of (125)I-radiolabeled c(RGDyK)-PEG-PLA or DiR encapsulated micelles and anti-glioblastoma pharmacological effect was investigated after intravenous administration. c(RGDyK)-PEG-PLA micelle accumulated in the subcutaneous and intracranial tumor tissue, and when loaded with PTX (c(RGDyK)-PEG-PLA-PTX), exhibited the strongest tumor growth inhibition among the studied paclitaxel formulations. The anti-glioblastoma effect of c(RGDyK)-PEG-PLA-PTX micelle was also reflected in the median survival time of mice bearing intracranial U87MG tumor xenografts where the median survival time of c(RGDyK)-PEG-PLA-PTX micelle-treated mice (48 days) was significantly longer than that of mice treated with PEG-PLA-PTX micelle (41.5 days), Taxol (38.5 days) or saline (34 days). Therefore, our results suggested that c(RGDyK)-PEG-PLA micelle may be a potential

  9. Safety evaluation of poly(lactic-co-glycolic acid)/poly(lactic-acid) microspheres through intravitreal injection in rabbits.

    PubMed

    Rong, Xianfang; Yuan, Weien; Lu, Yi; Mo, Xiaofen

    2014-01-01

    Poly(lactic-co-glycolic acid) (PLGA) and/or poly(lactic-acid) (PLA) microspheres are important drug delivery systems. This study investigated eye biocompatibility and safety of PLGA/PLA microspheres through intravitreal injection in rabbits. Normal New Zealand rabbits were randomly selected and received intravitreal administration of different doses (low, medium, or high) of PLGA/PLA microspheres and erythropoietin-loaded PLGA/PLA microspheres. The animals were clinically examined and sacrificed at 1, 2, 4, 8, and 12 weeks postadministration, and retinal tissues were prepared for analysis. Retinal reactions to the microspheres were evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end staining and glial fibrillary acidic protein immunohistochemistry. Retinal structure changes were assessed by hematoxylin and eosin staining and transmission electron microscopy. Finally, retinal function influences were explored by the electroretinography test. Terminal deoxynucleotidyl transferase-mediated dUTP nick end staining revealed no apoptotic cells in the injected retinas; immunohistochemistry did not detect any increased glial fibrillary acidic protein expression. Hematoxylin and eosin staining and transmission electron microscopy revealed no micro- or ultrastructure changes in the retinas at different time points postintravitreal injection. The electroretinography test showed no significant influence of scotopic or photopic amplitudes. The results demonstrated that PLGA/PLA microspheres did not cause retinal histological changes or functional damage and were biocompatible and safe enough for intravitreal injection in rabbits for controlled drug delivery.

  10. Conformation of poly(γ-glutamic acid) in aqueous solution.

    PubMed

    Muroga, Yoshio; Nakaya, Asami; Inoue, Atsuki; Itoh, Daiki; Abiru, Masaya; Wada, Kaori; Takada, Masako; Ikake, Hiroki; Shimizu, Shigeru

    2016-04-01

    Local conformation and overall conformation of poly(γ-DL-glutamic acid) (PγDLGA) and poly(γ-L-glutamic acid) (PγLGA) in aqueous solution was studied as a function of degree of ionization ε by (1) H-NMR, circular dichroism, and potentiometric titration. It was clarified that their local conformation is represented by random coil over an entire ε range and their overall conformation is represented by expanded random-coil in a range of ε > ε(*) , where ε(*) is about 0.3, 0.35, 0.45, and 0.5 for added-salt concentration of 0.02M, 0.05M, 0.1M, and 0.2M, respectively. In a range of ε < ε(*) , however, ε dependence of their overall conformation is significantly differentiated from each other. PγDLGA tends to aggregate intramolecularly and/or intermolecularly with decreasing ε, but PγLGA still behaves as expanded random-coil. It is speculated that spatial arrangement of adjacent carboxyl groups along the backbone chain essentially affects the overall conformation of PγGA in acidic media.

  11. Topological characterization of nanocrystalline cellulose reinforced Poly (lactic acid) and Poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) bionanocomposites

    NASA Astrophysics Data System (ADS)

    Bhat, A. H.; Dasan, Y. K.; Khan, Ihsan Ullah; Ahmad, Faiz; Ayoub, Muhammad

    2016-11-01

    This study was conducted to evaluate the morphological and barrier properties of nanocrystalline cellulose reinforced Poly (lactic acid) and Poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) bionanocomposites. Nanocrystalline cellulose was isolated from waste oil palm empty fruit bunch fiber using Sulphuric acid hydrolysis. Chemical modifications of nanocrystalline cellulose was performed to allow good compatibilization between fiber and the polymer matrices and also to improve dispersion of fillers. Bionanocomposite materials were produced from these nanocrystalline cellulose reinforced Poly (lactic acid) and Poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) using solvent casting and evaporation techniques. The properties of extracted nanocrystalline cellulose were examined using FT-IR spectroscopy, X-ray diffractometer, TEM and AFM. Besides that, the properties of bionanocomposites were examined through FESEM and oxygen permeability properties analysis. Better barrier and morphological properties were obtained for nanocrystalline cellulose reinforced bionanocomposites than for neat polymer blend.

  12. Chemical mechanical planarization of Ge2Sb2Te5 using IC1010 and Politex reg pads in acidic slurry

    NASA Astrophysics Data System (ADS)

    He, Ao-Dong; Liu, Bo; Song, Zhi-Tang; Wang, Liang-Yong; Liu, Wei-Li; Feng, Gao-Ming; Feng, Song-Lin

    2014-08-01

    In the paper, chemical mechanical planarization (CMP) of Ge2Sb2Te5 (GST) is investigated using IC1010 and Politex reg pads in acidic slurry. For the CMP with blank wafer, it is found that the removal rate (RR) of GST increases with the increase of pressure for both pads, but the RR of GST polished using IC1010 is far more than that of Politex reg. To check the surface defects, GST film is observed with an optical microscope (OM) and scanning electron microscope (SEM). For the CMP with Politex reg, many spots are observed on the surface of the blank wafer with OM, but no obvious spots are observed with SEM. With regard to the patterned wafer, a few stains are observed on the GST cell, but many residues are found on other area with OM. However, from SEM results, a few residues are observed on the GST cell, more dielectric loss is revealed about the trench structure. For the CMP with IC1010, the surface of the polished blank wafer suffers serious scratches found with both OM and SEM, which may result from a low hardness of GST, compared with those of IC1010 and abrasives. With regard to the patterned wafer, it can achieve a clean surface and almost no scratches are observed with OM, which may result from the high-hardness SiO2 film on the surface, not from the soft GST film across the whole wafer. From the SEM results, a clean interface and no residues are observed on the GST surface, and less dielectric loss is revealed. Compared with Politex reg, the patterned wafer can achieve a good performance after CMP using IC1010.

  13. Polynucleotides. XLVI. 1 Synthesis and properties of poly (2'-amino-2'-deoxyadenylic acid).

    PubMed

    Ikehara, M; Fukui, T; Kakiuchi, N

    1977-04-01

    Poly (2'-amino-2'-deoxyadenylic acid) [poly (Aa)] was prepared from chemically synthesized 2'-amino-2'-deoxy-ADP by the catalysis of polynucleotide phosphorylase. Poly (Aa) showed a similar UV absorption spectra to poly (A), but quite different CD spectra at pH 7.0 and 5.7. At the former pH it showed a single negative Cotton band and at the latter a curve with a large splitting of bands. Acid titration of poly (Aa) suggested protonated form below pH 7.0. Temperature absorption profiles and their dependency on sodium ion concentration suggested an ordered structure for poly (Aa) which is stabilized by stacking of bases and intrastrand interaction between 2'-amino and internucleotidic phosphate groups. Poly (Aa) forms a 1:2 complex with poly (U) at neutrality and its Tm was 45 degrees in the presence of 0.15M sodium ion.

  14. Poly(Lactic Acid) Hemodialysis Membranes with Poly(Lactic Acid)-block-Poly(2-Hydroxyethyl Methacrylate) Copolymer As Additive: Preparation, Characterization, and Performance.

    PubMed

    Zhu, Lijing; Liu, Fu; Yu, Xuemin; Xue, Lixin

    2015-08-19

    Poly(lactic acid) (PLA) hemodialysis membranes with enhanced antifouling capability and hemocompatibility were developed using poly(lactic acid)-block-poly(2-hydroxyethyl methacrylate) (PLA-PHEMA) copolymers as the blending additive. PLA-PHEMA block copolymers were synthesized via reversible addition-fragmentation (RAFT) polymerization from aminolyzed PLA. Gel permeation chromatography (GPC) and (1)H-nuclear magnetic resonance ((1)H NMR) were applied to characterize the synthesized products. By blending PLA with the amphiphilic block copolymer, PLA/PLA-PHEMA membranes were prepared by nonsolvent induced phase separation (NIPS) method. Their chemistry and structure were characterized with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and atomic force microscopy (AFM). The results revealed that PLA/PLA-PHEMA membranes with high PLA-PHEMA contents exhibited enhanced hydrophilicity, water permeability, antifouling and hemocompatibility. Especially, when the PLA-PHEMA concentration was 15 wt %, the water flux of the modified membrane was about 236 L m(-2) h(-1). Its urea and creatinine clearance was more than 0.70 mL/min, lysozyme clearance was about 0.50 mL/min, BSA clearance was as less as 0.31 mL/min. All the results suggest that PLA-PHEMA copolymers had served as effective agents for optimizing the property of PLA-based membrane for hemodialysis applications.

  15. Accelerated Amidization of Branched Poly(ethylenimine)/Poly(acrylic acid) Multilayer Films by Microwave Heating.

    PubMed

    Lin, Kehua; Gu, Yuanqing; Zhang, Huan; Qiang, Zhe; Vogt, Bryan D; Zacharia, Nicole S

    2016-09-13

    Chemical cross-linking of layer-by-layer assembled films promotes mechanical stability and robustness in a wide variety of environments, which can be a challenge for polyelectrolyte multilayers in saline environments or for multilayers made from weak polyelectrolytes in environments with extreme pHs. Heating branched poly(ethylenimine)/poly(acrylic acid) (BPEI/PAA) multilayers at sufficiently high temperatures drives amidization and dehydration to covalently cross-link the film, but this reaction is rather slow, typically requiring heating for hours for appreciable cross-linking to occur. Here, a more than one order of magnitude increase in the amidization kinetics is realized through microwave heating of BPEI/PAA multilayers on indium tin oxide (ITO)/glass substrates. The cross-linking reaction is tracked using infrared spectroscopic ellipsometry to monitor the development of the cross-linking products. For thick films (∼1500 nm), gradients in cross-link density can be readily identified by infrared ellipsometry. Such gradients in cross-link density are driven by the temperature gradient developed by the localized heating of ITO by microwaves. This significant acceleration of reactions using microwaves to generate a well-defined cross-link network as well as being a simple method for developing graded materials should open new applications for these polymer films and coatings.

  16. Immiscible poly(lactic acid)/poly(ε-caprolactone) for temporary implants: Compatibility and cytotoxicity.

    PubMed

    Finotti, Pablo F M; Costa, Lidiane C; Capote, Ticiana S O; Scarel-Caminaga, Raquel M; Chinelatto, Marcelo A

    2017-01-31

    This manuscript focuses on the effect of the addition of a low molecular weight triblock copolymer derived from ε-caprolactone and tetrahydrofuran (CT) on the compatibility and cytotoxicity of immiscible poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL) blends. Binary and tertiary PLA/PCL blends were prepared by melt mixing in a twin-screw extruder and their morphological, mechanical and thermal behaviors were investigated by scanning electron microscopy (SEM), tensile and Izod impact test, dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). SEM micrographs showed the CT copolymer suppressed the coalescence phenomena and maintained the size of dispersed PCL domains at approximately 0.35µm. Bioresorbable PLA/PCL blends containing 5wt% of CT copolymer exhibited a remarkable increase in ductility and improved toughness at room temperature. Although the CT copolymer increased the interfacial adhesion, the DMA results suggest it also acts as a plasticizer exclusively for the PCL phase. The cell viability evaluated by the XTT assay confirmed PLA/PCL blends compatibilized by CT copolymer exerted no cytotoxic effect.

  17. Dexamethasone-loaded poly(D, L-lactic acid) microspheres/poly(ethylene glycol)-poly(epsilon-caprolactone)-poly(ethylene glycol) micelles composite for skin augmentation.

    PubMed

    Fan, Min; Liao, Jinfeng; Guo, Gang; Ding, Qiuxia; Yang, Yi; Luo, Feng; Qian, Zhiyong

    2014-04-01

    Soft tissue augmentation using various injectable fillers has gained popularity as more patients seek esthetic improvement through minimally invasive procedures requiring little or no recovery time. The currently available injectable skin fillers can be divided into three categories. With careful assessment, stimulatory fillers are the most ideal fillers. In this study, dexamethasone-loaded poly(D, L-lactic acid) (PLA) microspheres of approximately 90 micro m suspended in poly(ethylene glycol)-poly(epsilon-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) micelles were prepared as stimulatory filler for skin augmentation. The biodegradable PECE copolymer can form nano-sized micelles in water, which instantly turns into a non-flowing gel at body temperature due to micellar aggregation. The PECE micelles (making up 90% of composite) served as vehicle for subcutaneous injection were metabolized within 44 days. At the same time, the dexamethasone-loaded PLA microspheres (10% of composite) merely served as stimulus for connective tissue formation. Dexamethasone-loaded PLA microspheres/PECE micelles composite presented great hemocompatibility in vitro. It was demonstrated in the in vive study that the composite was biodegradable, biocompatible, nontoxic and nonmigratory. Histopathological studies indicated that the composite could stimulate collagen regeneration. Furthermore, granuloma, the main complication of the stimulatory fillers, did not appear when the composite was injected into the back of SD rats, because of the dexamethasone controlled release from the composite. All results suggested that dexamethasone-loaded PLA microspheres/PECE micelles composite may be an efficient and promising biomaterial for skin augmentation.

  18. Synthesis and characterization of poly(lactic acid-co-glycolic acid) complex microspheres as drug carriers.

    PubMed

    Wang, Fang; Liu, Xiuxiu; Yuan, Jian; Yang, Siqian; Li, Yueqin; Gao, Qinwei

    2016-10-01

    Poly(lactic-co-glycolic) acid (PLGA) is synthesized via melt polycondensation directly from lactic acid and glycolic acid with a feed molar ratio of 75/25. Bovine serum albumin, which is used as model protein, is entrapped into the poly(lactic-co-glycolic acid) microspheres with particle size of 260.9 ± 20.0 nm by the double emulsification method. Then it is the first report of producing more carboxyl groups by poly(lactic-co-glycolic acid) surface hydrolysis. The purpose is developing poly(lactic-co-glycolic acid) microspheres surface, which is modified with chitosan by chemical reaction between carboxyl groups and amine groups. The particle size and the positive zeta potential of the poly(lactic-co-glycolic acid)/chitosan microspheres are 388.2 ± 35.6 nm and 10.4 ± 2.9 mV, respectively. The drug loading ratio and encapsulation efficacy of poly(lactic-co-glycolic acid)/chitosan microspheres are 36.3% and 57.5%, which are higher than PLGA microspheres. Furthermore, the drug burst release of poly(lactic-co-glycolic acid)/chitosan microspheres at 10 h is decreased to 21.72% while the corresponding value of the poly(lactic-co-glycolic acid) microsphere is 64.56%. These results reveal that surface hydrolysis modification of poly(lactic-co-glycolic acid) is an efficient method to improve the negative potential and chemical reaction properties of the polymer. And furthermore, this study shows that chitosan-modified poly(lactic-co-glycolic acid) microspheres is a promising system for the controlled release of pharmaceutical proteins.

  19. Poly(lactic acid) / Poly(ethylene glycol) blends: Mechanical, thermal and morphological properties

    NASA Astrophysics Data System (ADS)

    Bijarimi, M.; Ahmad, S.; Rasid, R.; Khushairi, M. A.; Zakir, M.

    2016-04-01

    The poly(lactic acid) (PLA) was melt blended with linear polyethylene glycol (PEG) in an effort to increase the toughness of PLA. Melt blending was carried out in an internal mixer at 180 °C mixing temperature with 50 rpm for 15 minutes. The blends were characterized in terms of mechanical, thermal and morphological properties. It was found that tensile and flexural strength, stiffness and notched Izod impact strength decreased significantly when the PEG was added to the PLA matrix at 2.5-10% of PEG concentrations. Both glass transition and melting temperatures (Tg and Tm) lowered as the concentration of PEG was increased. Moreover, it was noted that the PLA/PEG blends showed a lower onset and peak degradation temperatures but with lower final degradation temperature as compared to the neat PLA. The morphological analysis revealed that the PEG was dispersed as droplets in the PLA matrix with a clear boundary between PLA matrix and PEG phases.

  20. Poly(L-lactic acid)/poly(glycolic acid) microfibrillar polymer-polymer composites: Preparation and viscoelastic properties

    NASA Astrophysics Data System (ADS)

    Kimble, L. D.; Fakirov, S.; Bhattacharyya, D.

    2015-05-01

    Microfibrillar composites (MFCs) from petrochemical-derived polymers have been investigated for several years and the technique can result in significant improvements in mechanical properties when compared with the neat matrix material of the respective composite. The current work applies the technique to biodegradable, biocompatible polymers for potential applications in bioabsorbable medical devices. MFCs were prepared from melt blended poly(L-lactic acid) (PLLA) and poly(glycolic acid) (PGA) via cold drawing then compression molding of extruded yarn. These MFCs were shown to have higher Young's moduli than that of neat PLLA but for load-bearing applications the creep characteristics are of interest. The MFC sheets resulting from compression molding were subjected to tensile relaxation tests at 37°C in the fiber orientation direction. Specimens were also tested via dynamic mechanical thermal analysis (DMTA). Neat PLLA specimens were subjected to the same tests for comparison. Results indicate that at 37°C PLLA/PGA MFCs exhibit lower creep resistance than that of neat PLLA due to the more rapid relaxation of stress observed. DMTA results elucidate the loss modulus changes in PLLA/PGA MFCs which occur as the material approaches the glass transition temperature of PGA (˜45°C).

  1. Glycolic acid modulates the mechanical property and degradation of poly(glycerol, sebacate, glycolic acid).

    PubMed

    Sun, Zhi-Jie; Wu, Lan; Huang, Wei; Chen, Chang; Chen, Yan; Lu, Xi-Li; Zhang, Xiao-Lan; Yang, Bao-Feng; Dong, De-Li

    2010-01-01

    The development of biodegradable materials with controllable degradation properties is beneficial for a variety of applications. Poly(glycerol-sebacate) (PGS) is a promising candidate of biomaterials; so we synthesize a series of poly(glycerol, sebacate, glycolic acid) (PGSG) with 1:2:0, 1:2:0.2, 1:2:0.4, 1:2:0.6, 1:2:1 mole ratio of glycerol, sebacate, and glycolic acid to elucidate the relation of doped glycolic acid to the degradation rate and mechanical properties. The microstructures of the polymers with different doping of glycolic acid were dissimilar. PGSG with glycolic acid in the ratio of 0.2 displayed an integral degree of ordering, different to those with glycolic acid in the ratio of 0, 0.4, 0.6, and 1, which showed mild phase separation structure. The number, DeltaH(m), and temperature of the PGSG melting peaks tended to decrease with the increasing ratio of doped glycolic acid. In vitro and in vivo degradation tests showed that the degradation rate of PGSG with glycolic acid in the ratio of 0.2 was slowest, but in the ratio range of 0, 0.4, and 0.6, the degradation rate increased with the increase of glycolic acid. All PGSG samples displayed good tissue response and anticoagulant effects. Our data suggest that doping glycolic acid can modulate the microstructure and degree of crosslinking of PGS, thereby control the degradation rate of PGS.

  2. The alpha-glycosidic bonds of poly(ADP-ribose) are acid-labile.

    PubMed

    Panzeter, P L; Zweifel, B; Althaus, F R

    1992-04-15

    The poly(ADP-ribosyl)ation system of higher eukaryotes produces multiple ADP-ribose polymers of distinct sizes which exhibit different binding affinities for histones. Although precipitation with trichloroacetic acid (TCA) is the standard procedure for isolation of poly(ADP-ribose) from biological material, we show here that poly(ADP-ribose) is not stable under acidic conditions. Storage of poly(ADP-ribose) as TCA pellets results in acid hydrolysis of polymers, the extent of which is dependent on storage time and temperature. The alpha-glycosidic, inter-residue bonds are the preferred sites of attack, thus reducing polymer sizes by integral numbers of ADP-ribose to yield artefactually more and smaller polymers than originally present. Therefore, poly(ADP-ribosyl)ation studies involving TCA precipitation, histone extraction with acids, or acidic incubations of ADP-ribose polymers must account for the impact of acids on resulting polymer populations.

  3. Transient Current Behaviour of Poly (p-hydroxybenzoic acid-co-ethylene terephthalate) Liquid Crystal Polymers

    NASA Astrophysics Data System (ADS)

    Yarramaneni, Sridharbabu; Sharma, Anu; Quamara, J. K.

    2011-07-01

    Transient current behaviour of pristine Poly (p-hydroxybenzoic acid-co-ethylene terephthalate) Liquid crystal polymer which is a copolymer of poly ethylene terephthalate and poly p-hydroxybenzoic acid referred as PET/x.PHB polymer liquid crystals have been studied at different biasing electric fields ranging from 13 kV/cm to 104.3 kV/cm and at temperatures 120° C and 250° C for molar ratio x =0.8.

  4. Cholic acid functionalized star poly(DL-lactide) for promoting cell adhesion and proliferation.

    PubMed

    Fu, Hui-Li; Zou, Tao; Cheng, Si-Xue; Zhang, Xian-Zheng; Zhuo, Ren-Xi

    2007-01-01

    Cholic acid functionalized star poly(DL-lactide) was synthesized through the ring-opening polymerization of DL-lactide initiated by cholic acid. The properties and cell behaviour of the cholic acid functionalized star poly(DL-lactide) were investigated as compared with linear poly(DL-lactide)s with different molecular weights and a star poly(DL-lactide) initiated by glycerol. In comparison to linear poly(DL-lactide)s, the cholic acid functionalized star poly(DL-lactide) had better wettability and slightly higher surface energy. The cell adhesion and proliferation on different materials were evaluated using two types of cells, 3T3 mouse fibroblasts and ECV304 human endothelial cells. Compared with the linear poly(DL-lactide)s, the cholic acid functionalized star poly(DL-lactide) showed obviously improved property for cell adhesion. The cell proliferation on the cholic acid functionalized star poly(DL-lactide) was also enhanced. The improvement in cell proliferation was not so significant as compared with the improvement in cell adhesion. This modification strategy provides an effective and simple way to promote cell attachment and growth in tissue engineering.

  5. NOVEL POLY-GLUTAMIC ACID FUNCTIONALIZED MICROFILTRATION MEMBRANES FOR SORPTION OF HEAVY METALS AT HIGH CAPACITY

    EPA Science Inventory

    Various sorbent/ion exchange materials have been reported in the literature for metal ion entrapment. We have developed a highly innovative and new approach to obtain high metal pick-up utilizing poly-amino acids (poly-L-glutamic acid, 14,000 MW) covalently attached to membrane p...

  6. Application of poly(lactic acid) modified by radiation crosslinking

    NASA Astrophysics Data System (ADS)

    Nagasawa, Naotsugu; Kaneda, Ayako; Kanazawa, Shinichi; Yagi, Toshiaki; Mitomo, Hiroshi; Yoshii, Fumio; Tamada, Masao

    2005-07-01

    Poly(L-lactic acid), PLLA was irradiated using electron beam (EB) in the presence of polyfunctional monomers (PFM) as crosslinking agent. Among the PFMs, triallyl isocyanurate (TAIC) at 3% concentration was found to be the most effective for crosslinking of PLLA by irradiation technique. The crosslinked PLLA obtained has heat resistance higher than 200 °C. From this fact, the crosslinked PLLA is applied on heat-shrinkable tube, cup and plate. The shrinkable tube has several advantages such as high heat resistance and transparency. In addition, the unirradiated cup deformed and changed to milky-like transparency but the crosslinked one retained its original shape and transparency after boiling water was poured into the cups. The heat resistance is attributed to the protection of crystallization of crosslinking structure. It is therefore proven that crosslinking technology is beneficial to expanding the application of PLLA.

  7. Radiation synthesis of nanosilver nanohydrogels of poly(methacrylic acid)

    NASA Astrophysics Data System (ADS)

    Gupta, Bhuvanesh; Gautam, Deepti; Anjum, Sadiya; Saxena, Shalini; Kapil, Arti

    2013-11-01

    Nanosilver nanohydrogels (nSnH) of poly(methacrylic acid) were synthesized and stabilized using gamma irradiation. The main objective of this study was to develop silver nanoparticles and to evaluate the antimicrobial activity. Radiation helps in the polymerization, crosslinking and reduction of silver nitrate as well. Highly stable and uniformly distributed silver nanoparticles have been obtained within hydrogel network by water in oil nanoemulsion polymerization and were evaluated by dynamic light scattering (DLS) and transmission electron microscopy (TEM) respectively. TEM showed almost spherical and uniform distribution of silver nanoparticles through the hydrogel network. The mean size of silver nanoparticles ranging is 10-50 nm. The nanohydrogels showed good swelling in water. Antibacterial studies of nSnH suggest that it can be a good candidate as coating material in biomedical applications.

  8. Poly(lactic acid) for delivery of bioactive macromolecules.

    PubMed

    James, Roshan; Manoukian, Ohan S; Kumbar, Sangamesh G

    2016-12-15

    Therapeutic biomolecules often require frequent administration and supramolecular dosing to achieve therapeutic efficiencies and direct infusion into treatment or defect sites results in inadequate physiological response and at times severe side effects or mis-targeting. Delivery systems serve several purposes such as increased circulatory time, increased biomolecule half-life, and incorporation of new innovations can enable highly specific cell targeting and improved cell and nucleus permeability. Poly(lactic acid) (PLA) has become a "material of choice" due to wide availability, reproducible synthetic route, customization, versatility, biodegradability and biocompatibility. Furthermore, PLA is amenable to a variety of fabrication methodologies and chemistries allowing an expansive library correlating physio-chemical properties, characteristics, and applications. This article discusses challenges to biomolecule delivery, and classical approaches of PLA based biomolecule delivery and targeting strategies under development and in trials.

  9. The Shigella Virulence Factor IcsA Relieves N-WASP Autoinhibition by Displacing the Verprolin Homology/Cofilin/Acidic (VCA) Domain*

    PubMed Central

    Mauricio, Rui P. M.; Jeffries, Cy M.; Svergun, Dmitri I.; Deane, Janet E.

    2017-01-01

    Shigella flexneri is a bacterial pathogen that invades cells of the gastrointestinal tract, causing severe dysentery. Shigella mediates intracellular motility and spreading via actin comet tail formation. This process is dependent on the surface-exposed, membrane-embedded virulence factor IcsA, which recruits the host actin regulator N-WASP. Although it is clear that Shigella requires N-WASP for this process, the molecular details of this interaction and the mechanism of N-WASP activation remain poorly understood. Here, we show that co-expression of full-length IcsA and the Shigella membrane protease IcsP yields highly pure IcsA passenger domain (residues 53–758). We show that IcsA is monomeric and describe the solution structure of the passenger domain obtained by small-angle X-ray scattering (SAXS) analysis. The SAXS-derived models suggest that IcsA has an elongated shape but, unlike most other autotransporter proteins, possesses a central kink revealing a distinctly curved structure. Pull-down experiments show direct binding of the IcsA passenger domain to both the WASP homology 1 (WH1) domain and the GTPase binding domain (GBD) of N-WASP and no binding to the verprolin homology/cofilin/acidic (VCA) region. Using fluorescence polarization experiments, we demonstrate that IcsA binding to the GBD region displaces the VCA peptide and that this effect is synergistically enhanced upon IcsA binding to the WH1 region. Additionally, domain mapping of the IcsA interaction interface reveals that different regions of IcsA bind to the WH1 and GBD domains of N-WASP. Taken together, our data support a model where IcsA and N-WASP form a tight complex releasing the N-WASP VCA domain to recruit the host cell machinery for actin tail formation. PMID:27881679

  10. Biomimetic poly(glycerol sebacate)/poly(l-lactic acid) blend scaffolds for adipose tissue engineering.

    PubMed

    Frydrych, Martin; Román, Sabiniano; MacNeil, Sheila; Chen, Biqiong

    2015-05-01

    Large three-dimensional poly(glycerol sebacate) (PGS)/poly(l-lactic acid) (PLLA) scaffolds with similar bulk mechanical properties to native low and high stress adapted adipose tissue were fabricated via a freeze-drying and a subsequent curing process. PGS/PLLA scaffolds containing 73vol.% PGS were prepared using two different organic solvents, resulting in highly interconnected open-pore structures with porosities and pore sizes in the range of 91-92% and 109-141μm, respectively. Scanning electron microscopic analysis indicated that the scaffolds featured different microstructure characteristics, depending on the organic solvent in use. The PGS/PLLA scaffolds had a tensile Young's modulus of 0.030MPa, tensile strength of 0.007MPa, elongation at the maximum stress of 25% and full shape recovery capability upon release of the compressive load. In vitro degradation tests presented mass losses of 11-16% and 54-55% without and with the presence of lipase enzyme in 31days, respectively. In vitro cell tests exhibited clear evidence that the PGS/PLLA scaffolds prepared with 1,4-dioxane as the solvent are suitable for culture of adipose derived stem cells. Compared to pristine PLLA scaffolds prepared with the same procedure, these scaffolds provided favourable porous microstructures, good hydrophilic characteristics, and appropriate mechanical properties for soft tissue applications, as well as enhanced scaffold cell penetration and tissue in-growth characteristics. This work demonstrates that the PGS/PLLA scaffolds have potential for applications in adipose tissue engineering.

  11. Blood compatibility evaluations of poly(ethylene glycol)-poly(lactic acid) copolymers.

    PubMed

    Li, Chenghua; Ma, Chengyan; Zhang, Yi; Liu, Zonghua; Xue, Wei

    2016-05-01

    Poly(ethylene glycol)-poly(lactic acid) (PEG-PLA) copolymers have been widely used for various biomedical applications. However, their hemocompatibility has not been clarified, which would lag their developments and clinical applications. In this work, we studied the effect of PEG-PLA copolymers on key human blood components in terms of their structure and bio-functions, including morphology and lysis of red blood cells, fibrinogen structure and conformation, and plasma and blood coagulation. To elucidate a structure-activity relationship, we used diblock PEG-PLA copolymers with different molecular weight, PEG(5 kDa)-PLA(25 kDa) and PEG(2 kDa)-PLA(2 kDa), abbreviated as PEG5k-PLA25k and PEG2k-PLA2k, respectively. The results show that the PEG-PLA copolymers at the concentration range studied in this work neither caused morphological alteration and lysis of red blood cells nor affected the oxygen delivery function and fibrinogen conformation. PEG5k-PLA25k from 10 to 100 mg/mL and PEG2k-PLA2k from 1.5 to 5 mg/mL disturbed the local microenvironments of fibrinogen molecules. PEG5k-PLA25k at up to 0.1 mg/mL did not interfere in the coagulation process of plasma or whole blood, while PEG2k-PLA2k from 0.1 mg/mL significantly interfered in the intrinsic plasma coagulation pathway and impaired whole blood coagulation. The results provide important information for the molecular design and clinical applications of PEG-PLA copolymers.

  12. Preparation and in vitro characterization of dexamethasone-loaded poly(D,L-lactic acid) microspheres embedded in poly(ethylene glycol)-poly({varepsilon}-caprolactone)-poly(ethylene glycol) hydrogel for orthopedic tissue engineering.

    PubMed

    Fan, Min; Guo, QingFa; Luo, JingCong; Luo, Feng; Xie, Ping; Tang, XiaoHai; Qian, ZhiYong

    2013-08-01

    The corium is decreased to about half of its thickness in skin defects and wrinkles due to gravity and environment. In this study, dexamethasone/poly(d,l-lactic acid) (Mn = 160,000) microspheres were incorporated into poly(ethylene glycol)-poly(ε-caprolactone)-poly(ethylene glycol) (Mn = 3300) hydrogel to prepare an injectable hydrogel composite. The composite was designed to increase the thickness of the corium. Dexamethasone/poly(d,l-lactic acid) microspheres were prepared by oil-in-water emulsion/solvent evaporation technique. The properties of microspheres were investigated by size distribution measurement, scanning electron microscope and x-ray diffraction. Drug loading, encapsulation efficiency, and drug delivery behavior of microspheres were also studied in detail. Cell adhesion of microspheres was investigated by NIH3T3 cell in vitro. The properties of hydrogel composite were investigated by scanning electron microscope, rheological measurements and methyl thiazolyl tetrazolium assay. Drug release from composite was determined by HPLC-UV analysis. These results suggested that poly(d,l-lactic acid) microspheres encapsulating dexamethasone embedded in poly(ethylene glycol)-poly(ε-caprolactone)-poly(ethylene glycol) hydrogel might have prospective application in orthopedic tissue engineering field.

  13. Poly(acrylic acid) to induce competitive crystallization of a theophylline/oxalic acid cocrystal and a theophylline polymorph

    NASA Astrophysics Data System (ADS)

    Jang, Jisun; Kim, Il Won

    2016-01-01

    Polymeric additives to induce competitive crystallization of pharmaceutical compounds were explored. A cocrystal of theophylline and oxalic acid was used as a model system, and poly(acrylic acid), poly(caprolactone), and poly(ethylene glycol) were the additives. The cocrystal formation was selectively hindered with addition of poly(acrylic acid). First the size of the cocrystals were reduced, and eventually the cocrystallization was inhibited to generate neat theophylline crystals. The theophylline crystals were of a distinctively different crystal structure from known polymorphs, based on powder X-ray diffraction. They were also obtained in nanoscale size, when millimeter-scale crystals formed without poly(acrylic acid). Polymeric additives that could form specific interactions with crystallizing compounds seem to be useful tools for the phase and size control of pharmaceutical crystals.

  14. Detection, isolation, and characterization of oligo/poly(sialic acid) and oligo/poly(deaminoneuraminic acid) units in glycoconjugates.

    PubMed

    Kitazume, S; Kitajima, K; Inoue, S; Inoue, Y

    1992-04-01

    We have evaluated methods for separation, preparation, and characterization of alpha-2----8-linked oligomers of sialic acids (Neu5Ac and Neu5Gc) and deaminated neuraminic acid (KDN; 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid) recently found as a naturally occurring novel type of sialic acid analogue. (A) We examined preparative anion-exchange chromatography for fractionation and preparation of oligo(Neu5Ac), oligo(Neu5Gc), and oligo(KDN). (B) We also examined the TLC method for separation and differentiation of the partial acid hydrolysates of colominic acid, as well as polysialoglycoproteins (PSGP) and poly(KDN)-glycoproteins (KDN-gp) isolated from rainbow trout eggs, and for discrimination of lower oligomers of Neu5Ac, Neu5Gc, and KDN. (C) We developed the high-performance adsorption-partition chromatographic method for (a) separation of monomers and oligomers of three nonulosonates according to the difference in substituents at C-5 and the presence or absence of 9-O-acetyl groups in oligo(KDN) and (b) separation of three homologous series of lower oligomers according to the degree of polymerization. (D) We examined and compared high-performance anion-exchange chromatographic separation of 3H-labeled oligo(Neu5Ac), oligo(Neu5Gc), and oligo(KDN) alditols by using Mono-Q HR 5/5 resin. (E) We examined a method of selective and quantitative microprecipitation for separation and purification of oligomers and polymers of Neu5Ac by treating them with cetylpyridinium chloride. We also used PSGP and KDN-gp to test both the sensitivity and the selectivity of this method.

  15. Poly(lactic acid-co-glycolic acid)-poly(ethylene glycol)-poly(lactic acid-co-glycolic acid) thermogel as a novel submucosal cushion for endoscopic submucosal dissection.

    PubMed

    Yu, Lin; Xu, Wei; Shen, Wenjia; Cao, Luping; Liu, Yan; Li, Zhaoshen; Ding, Jiandong

    2014-03-01

    Endoscopic submucosal dissection (ESD) is a clinical therapy for early stage neoplastic lesions in the gastrointestinal tract. It is, however, faced with a crucial problem: the high occurrence of perforation. The formation of a submucosal fluid cushion (SFC) via a fluid injection is the best way to avoid perforation, and thus an appropriate biomaterial is vital for this minimally invasive endoscopic technique. In this study, we introduced an injectable thermogel as a novel submucosal injection substance in ESD. The hydrogel synthesized by us was composed of poly(lactic acid-co-glycolic acid)-poly(ethylene glycol)-poly(lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) triblock copolymers. The polymer/water system was a low-viscosity fluid at room temperature and thus easily injected, and turned into a non-flowing gel at body temperature after injection. The submucosal injection of the thermogel to create SFCs was performed in both resected porcine stomachs and living minipigs. High mucosal elevation with a clear margin was maintained for a long duration. Accurate en bloc resection was achieved with the assistance of the thermogel. The mean procedure time was strikingly reduced. Meanwhile, no obvious bleeding, perforation and tissue damage were observed. The application of the thermogel not only facilitated the ESD procedure, but also increased the efficacy and safety of ESD. Therefore, the PLGA-PEG-PLGA thermogel provides an excellent submucosal injection system, and has great potential to improve the ESD technique significantly.

  16. Reactive Poly(Amic Acid)/ Poly(Glycidyl Methacrylate-r-Poly(ethylene Glycol) Methyl Ether Methacrylate) Blends as Gas Permeation Membranes

    NASA Astrophysics Data System (ADS)

    Beaulieu, Michael; Watkins, James

    2012-02-01

    Polymers containing polar moieties, such as ether groups show an affinity for acidic gases, such as CO2 due to dipole-quadrapole interactions. Polymer blends in which one of the components is poly(ethylene glycol) (PEG) have been studied extensively in literature as a CO2/light gas permeation membrane, but due to the crystallization and poor mechanical properties have been difficult to incorporate PEG above 60wt%. In this study, a series of random copolymers containing both glycidyl methacrylate and poly(ethylene glycol) methyl ether methacrylate in different ratios are blended with a poly(amic acid) prepolymer made from 4, 4'-oxydianiline and pyromellitic dianhydride to create gas permeation membranes. By using a reactive blend PEG loadings above 70% have been realized with sufficient mechanical properties, and since the side chain on the PEGMA is short these blends do not suffer from crystallization.

  17. Poly(lactic-co-glycolic acid) conduit for repair of injured sciatic nerve: A mechanical analysis

    PubMed Central

    Yu, Tao; Zhao, Changfu; Li, Peng; Liu, Guangyao; Luo, Min

    2013-01-01

    Tensile stress and tensile strain directly affect the quality of nerve regeneration after bridging nerve defects by poly(lactic-co-glycolic acid) conduit transplantation and autogenous nerve grafting for sciatic nerve injury. This study collected the sciatic nerve from the gluteus maximus muscle from fresh human cadaver, and established 10-mm-long sciatic nerve injury models by removing the ischium, following which poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts were transplanted. Scanning electron microscopy revealed that the axon and myelin sheath were torn, and the vessels of basilar membrane were obstructed in the poly(lactic-co-glycolic acid) conduit-repaired sciatic nerve following tensile testing. There were no significant differences in tensile tests with autogenous nerve graft-repaired sciatic nerve. Following poly(lactic-co-glycolic acid) conduit transplantation for sciatic nerve repair, tensile test results suggest that maximum tensile load, maximum stress, elastic limit load and elastic limit stress increased compared with autogenous nerve grafts, but elastic limit strain and maximum strain decreased. Moreover, the tendencies of stress-strain curves of sciatic nerves were similar after transplantation of poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts. Results showed that after transplantation in vitro for sciatic nerve injury, poly(lactic-co-glycolic acid) conduits exhibited good intensity, elasticity and plasticity, indicating that poly(lactic-co-glycolic acid) conduits are suitable for sciatic nerve injury repair. PMID:25206505

  18. Poly(lactic-co-glycolic acid) conduit for repair of injured sciatic nerve: A mechanical analysis.

    PubMed

    Yu, Tao; Zhao, Changfu; Li, Peng; Liu, Guangyao; Luo, Min

    2013-07-25

    Tensile stress and tensile strain directly affect the quality of nerve regeneration after bridging nerve defects by poly(lactic-co-glycolic acid) conduit transplantation and autogenous nerve grafting for sciatic nerve injury. This study collected the sciatic nerve from the gluteus maximus muscle from fresh human cadaver, and established 10-mm-long sciatic nerve injury models by removing the ischium, following which poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts were transplanted. Scanning electron microscopy revealed that the axon and myelin sheath were torn, and the vessels of basilar membrane were obstructed in the poly(lactic-co-glycolic acid) conduit-repaired sciatic nerve following tensile testing. There were no significant differences in tensile tests with autogenous nerve graft-repaired sciatic nerve. Following poly(lactic-co-glycolic acid) conduit transplantation for sciatic nerve repair, tensile test results suggest that maximum tensile load, maximum stress, elastic limit load and elastic limit stress increased compared with autogenous nerve grafts, but elastic limit strain and maximum strain decreased. Moreover, the tendencies of stress-strain curves of sciatic nerves were similar after transplantation of poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts. Results showed that after transplantation in vitro for sciatic nerve injury, poly(lactic-co-glycolic acid) conduits exhibited good intensity, elasticity and plasticity, indicating that poly(lactic-co-glycolic acid) conduits are suitable for sciatic nerve injury repair.

  19. Biocompatibility of poly(lactic acid) with incorporated graphene-based materials.

    PubMed

    Pinto, Artur M; Moreira, Susana; Gonçalves, Inês C; Gama, Francisco M; Mendes, Adélio M; Magalhães, Fernão D

    2013-04-01

    The incorporation of graphene-based materials has been shown to improve mechanical properties of poly(lactic acid) (PLA). In this work, PLA films and composite PLA films incorporating two graphene-based materials - graphene oxide (GO) and graphene nanoplatelets (GNP) - were prepared and characterized regarding not only biocompatibility, but also surface topography, chemistry and wettability. The presence of both fillers changed the films surface topography, increasing the roughness, and modified the wettability - the polar component of surface free energy increased 59% with GO and decreased 56% with GNP. Mouse embryo fibroblasts incubated with both fillers exceeded the IC(50) in both cases with a concentration of 10 μg mL(-1). No variations in cell proliferation at the surface of the composite films were observed, except for those containing GO after 24 h incubation, which presented higher cell proliferation than pristine PLA films. Platelet adhesion to PLA and PLA/GNP films was lower in the presence of plasma proteins than when no proteins were present. Furthermore, incorporation of GNP into PLA reduced platelet activation in the presence of plasma proteins. The results indicated that low concentrations of GO and GNP may be incorporated safely in PLA to improve aspects relevant for biomedical applications, such as mechanical properties.

  20. Fabrication and characterization of novel multilayered structures by stereocomplexion of poly(D-lactic acid)/poly(L-lactic acid) and self-assembly of polyelectrolytes

    PubMed Central

    Yang, Gesheng; Pastorino, Laura

    2016-01-01

    Summary The enantiomers poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA) were alternately adsorbed directly on calcium carbonate (CaCO3) templates and on poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) multilayer precursors in order to fabricate a novel layer-by-layer (LBL) assembly. A single layer of poly(L-lysine) (PLL) was used as a linker between the (PDLA/PLLA)n stereocomplex and the cores with and without the polymeric (PSS/PAH)n/PLL multilayer precursor (PEM). Nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) were used to characterize the chemical composition and molecular weight of poly(lactic acid) polymers. Both multilayer structures, with and without polymeric precursor, were firstly fabricated and characterized on planar supports. A quartz crystal microbalance (QCM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and ellipsometry were used to evaluate the thickness and mass of the multilayers. Then, hollow, spherical microcapsules were obtained by the removal of the CaCO3 sacrificial template. The chemical composition of the obtained microcapsules was confirmed by differential scanning calorimetry (DSC) and wide X-ray diffraction (WXRD) analyses. The microcapsule morphology was evaluated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements. The experimental results confirm the successful fabrication of this innovative system, and its full biocompatibility makes it worthy of further characterization as a promising drug carrier for sustained release. PMID:26925356

  1. Self-doping effect in poly(o-methoxyaniline)/poly(3-thiopheneacetic acid) layer-by-layer films.

    PubMed

    Trivinho-Strixino, Francisco; Pereira, Ernesto C; Mello, Sarita V; Oliveira, Osvaldo N

    2004-04-27

    Nanostructured films from two conducting polymers, poly(o-methoxyaniline) (POMA) and poly(3-thiopheneacetic acid) (PTAA), were fabricated with the layer-by-layer (LBL) technique. The electrochemical response of the LBL films differs from that of a POMA cast film, even in a potential range where PTAA is inactive. This is attributed to differences in the diffusion-controlled charge and mass transport, where distinct ionic species participate in the LBL films, as demonstrated by quartz crystal microbalance measurements. The results show that the transport properties of conducting polymers can be changed by alternation with layers of appropriate materials in LBL films.

  2. Synthesis and characterization of a poly(lactic-co-glycolic acid) core + poly(N-isopropylacrylamide) shell nanoparticle system.

    PubMed

    Kosinski, Aaron M; Brugnano, Jamie L; Seal, Brandon L; Knight, Frances C; Panitch, Alyssa

    2012-01-01

    Poly(lactic-co-glycolic acid) (PLGA) is a popular material used to prepare nanoparticles for drug delivery. However, PLGA nanoparticles lack desirable attributes including active targeting abilities, resistance to aggregation during lyophilization, and the ability to respond to dynamic environmental stimuli. To overcome these issues, we fabricated a nanoparticle consisting of a PLGA core encapsulated within a shell of poly(N-isopropylacrylamide). Dynamic light scattering and transmission electron microscope imaging were used to characterize the nanoparticles, while an MTT assay and ELISA suggested biocompatibility in THP1 cells. Finally, a collagen type II binding assay showed successful modification of these nanoparticles with an active targeting moiety.

  3. Poly(L-aspartic acid) derivative soluble in a volatile organic solvent for biomedical application.

    PubMed

    Oh, Nam Muk; Oh, Kyung Taek; Youn, Yu Seok; Lee, Eun Seong

    2012-09-01

    In order to develop a novel functional poly(L-amino acid) that can dissolve in volatile organic solvents, we prepared poly[L-aspartic acid-g-(3-diethylaminopropyl)]-b-poly(ethylene glycol) [poly(L-Asp-g-DEAP)-b-PEG] via the conjugation of 3-diethylaminopropyl (DEAP) to carboxylate groups of poly(L-Asp) (M(n) 4 K)-b-PEG (M(n) 2 K). This poly(L-aspartic acid) derivative evidenced a relatively high solubility in volatile organic solvents such as dichloromethane, chloroform, and acetone. We fabricated a model nanostructure (i.e., polymeric micelle) using poly(L-Asp-g-DEAP)-b-PEG by the film rehydration method, which involves the simple removal of the volatile organic solvent (dichloromethane) used to dissolve polymer, reducing concerns about organic solvents remaining in a nano-sized particle. Interestingly, this micelle showed the pH-stimulated release of encapsulated model drug [i.e., doxorubicin (DOX)] due to the protonation of DEAP according to the pH of the solution. We expect that this poly(L-aspartic acid) derivative promises to provide pharmaceutical potential for constituting a new stimuli-sensitive drug carrier for various drug molecules.

  4. Electrospun poly(vinylidene fluoride)/poly(aminophenylboronic acid) composite nanofibrous membrane as a novel glucose sensor.

    PubMed

    Manesh, K M; Santhosh, P; Gopalan, A; Lee, Kwang-Pill

    2007-01-15

    Electrospinning was used to prepare the nanofibrous membrane (NFM) of the composite comprising poly(vinylidene fluoride) and poly(aminophenylboronic acid) (PVdF/PAPBA-NFM). The PVdF/PAPBA-NFM displayed an excellent linear response to the detection of glucose for the concentration range of 1 to 15mM with a response time of less than 6s. Further experiments on amperometric sensing of glucose were performed in the presence of interferents such as uric acid, ascorbic acid, acetaminophen, fructose, mannose, etc. using PVdF/PAPBA-NFM. The interferents did not give significant overlapping current signal during the determination of glucose. Also, PVdF/PAPBA-NFM possesses better reproducibility toward glucose detection and storage stability.

  5. The study of gamma irradiation effects on poly (glycolic acid)

    NASA Astrophysics Data System (ADS)

    Rao Nakka, Rajeswara; Rao Thumu, Venkatappa; Reddy SVS, Ramana; Rao Buddhiraju, Sanjeeva

    2015-05-01

    We have investigated the effects of gamma irradiation on chemical structure, thermal and morphological properties of biodegradable semi-crystalline poly (glycolic acid) (PGA). PGA samples were subjected to irradiation treatment using a 60Co gamma source with a delivered dose of 30, 60 and 90 kGy, respectively. Gamma irradiation induces cleavage of PGA main chains forming ∼OĊH2 and ĊH2COO∼ radicals in both amorphous and crystalline regions. The free radicals formed in the amorphous region abstract atmospheric oxygen and convert them to peroxy radicals. The peroxy radical causes chain scission at the crystal interface through hydrogen abstraction from methylene groups forming the ∼ĊHCOO∼ (I) radical. Consequently, the observed electron spin resonance (ESR) doublet of irradiated PGA is assigned to (I). The disappearance of the ESR signal above 190°C indicates that free radicals are formed in the amorphous region and decay below the melting temperature of PGA. Fourier transform infrared and optical absorption studies confirm that the ? groups are not influenced by gamma irradiation. Differential scanning calorimetry (DSC) studies showed that the melting temperature of PGA decreased from 212°C to 202°C upon irradiation. Degree of crystallinity increased initially and then decreased with an increase in radiation as per DSC and X-ray diffraction studies. Irradiation produced changes in the physical properties of PGA as well as affecting the morphology of the material.

  6. Interaction of photosensitive surfactant with DNA and poly acrylic acid

    SciTech Connect

    Zakrevskyy, Yuriy Paasche, Jens; Lomadze, Nino; Santer, Svetlana; Cywinski, Piotr; Cywinska, Magdalena; Reich, Oliver; Löhmannsröben, Hans-Gerd

    2014-01-28

    In this paper, we investigate interactions and phase transitions in polyelectrolyte-surfactant complexes formed between a cationic azobenzene-containing surfactant and two types of polyelectrolytes: natural (DNA) or synthetic (PAA: poly acrylic acid). The construction of a phase diagram allowed distancing between four major phases: extended coil conformation, colloidally stable compacted globules, colloidal instability range, and surfactant-stabilized compact state. Investigation on the complexes’ properties in different phases and under irradiation with UV light provides information about the role of the surfactant's hydrophobic trans isomers both in the formation and destruction of DNA and PAA globules as well as in their colloidal stabilization. The trans isomer shows much stronger affinity to the polyelectrolytes than the hydrophilic cis counterpart. There is no need for complete compensation of the polyelectrolyte charges to reach the complete compaction. On contrary to the findings previously reported in the literature, we demonstrate – for the first time – complete polyelectrolyte compaction which occurs already at 20% of DNA (and at 50% of PAA) charge compensation. The trans isomer plays the main role in the compaction. The aggregation between azobenzene units in the photosensitive surfactant is a driving force of this process. The decompaction can be realized during UV light irradiation and is strongly influenced by the interplay between surfactant-surfactant and surfactant-DNA interactions in the compacted globules.

  7. Heat Capacity of Poly(L-lactic acid)

    NASA Astrophysics Data System (ADS)

    Pyda, Marek; Bopp, C. Bopp Richard C.; Richard, C.; Wunderlich, Bernhard

    2002-03-01

    The heat capacity of poly(L-lactic acid) (PLA) is reported from 5-520 K from standard differential scanning calorimetry (DSC), temperature modulated DSC (TMDSC), and adiabatic calorimetry. The semicrystalline PLA has a melting endotherm between 418 and 432 K, with variable heats of fusion, depending on thermal history. The thermodynamic heat of fusion is 6.15 kJ/mol. The heat capacity is linked to its group vibrational spectrum and the skeletal vibrations described by the Tarasov equation (theta parameters 574 and 52 K, N = 9). Calculated and experimental heat capacities agree to ±3compares within ±0.5contributions of other polymers with the same constituent groups. The glass transition temperature of liquid PLA is at 333 K with a change in heat capacity of about 41 J/(K mol). With these results, the enthalpy, entropy, and Gibbs function were obtained. For semicrystalline samples one can then discuss the crystallinity changes with temperature, the question of a rigid-amorphous fraction, and the reversible melting. --- Supported by NSF, Polymers Program, DMR-9703692, and the Div. of Mat. Sci., BES, DOE at ORNL, managed by UT-Batelle, LLC, for the U.S. Department of Energy, under contract number DOE-AC05-00OR22725.

  8. Supermacroporous chemically cross-linked poly(aspartic acid) hydrogels.

    PubMed

    Gyarmati, Benjámin; Mészár, E Zsuzsanna; Kiss, Lóránd; Deli, Mária A; László, Krisztina; Szilágyi, András

    2015-08-01

    Chemically cross-linked poly(aspartic acid) (PASP) gels were prepared by a solid-liquid phase separation technique, cryogelation, to achieve a supermacroporous interconnected pore structure. The precursor polymer of PASP, polysuccinimide (PSI) was cross-linked below the freezing point of the solvent and the forming crystals acted as templates for the pores. Dimethyl sulfoxide was chosen as solvent instead of the more commonly used water. Thus larger temperatures could be utilized for the preparation and the drawback of increase in specific volume of water upon freezing could be eliminated. The morphology of the hydrogels was characterized by scanning electron microscopy and interconnectivity of the pores was proven by the small flow resistance of the gels. Compression tests also confirmed the interconnected porous structure and the complete re-swelling and shape recovery of the supermacroporous PASP hydrogels. The prepared hydrogels are of interest for several biomedical applications as scaffolding materials because of their cytocompatibility, controllable morphology and pH-responsive character.

  9. Electrospun poly(lactic acid) based conducting nanofibrous networks

    NASA Astrophysics Data System (ADS)

    Patra, S. N.; Bhattacharyya, D.; Ray, S.; Easteal, A. J.

    2009-08-01

    Multi-functionalised micro/nanostructures of conducting polymers in neat or blended forms have received much attention because of their unique properties and technological applications in electrical, magnetic and biomedical devices. Biopolymer-based conducting fibrous mats are of special interest for tissue engineering because they not only physically support tissue growth but also are electrically conductive, and thus are able to stimulate specific cell functions or trigger cell responses. They are effective for carrying current in biological environments and can thus be considered for delivering local electrical stimuli at the site of damaged tissue to promote wound healing. Electrospinning is an established way to process polymer solutions or melts into continuous fibres with diameter often in the nanometre range. This process primarily depends on a number of parameters, including the type of polymer, solution viscosity, polarity and surface tension of the solvent, electric field strength and the distance between the spinneret and the collector. The present research has included polyaniline (PANi) as the conducting polymer and poly(L-lactic acid) (PLLA) as the biopolymer. Dodecylbenzene sulphonic acid (DBSA) doped PANi and PLLA have been dissolved in a common solvent (mixtures of chloroform and dimethyl formamide (DMF)), and the solutions successfully electrospun. DMF enhanced the dielectric constant of the solvent, and tetra butyl ammonium bromide (TBAB) was used as an additive to increase the conductivity of the solution. DBSA-doped PANi/PLLA mat exhibits an almost bead-free network of nanofibres that have extraordinarily smooth surface and diameters in the range 75 to 100 nm.

  10. CHARACTERIZATION OF SULFUR CONTAINING ANALOGS OF MONOMETHYLARSONIC ACID IN AQUEOUS PHASE STANDARDS AND CARROT EXTRACTS BY IC-ICP-MS AND IC-ESI-MS/MS

    EPA Science Inventory

    Recently, sulfur analogs of well known arsenicals have been identified, generating a need for stable species-specific standards. This presentation will focus on the identification and characterization of a novel species, monomethylthioarsonic acid (MMTA), in carrots. A standard...

  11. Preparation and characterization of reactive blends of poly(lactic acid), poly(ethylene-co-vinyl alcohol), and poly(ethylene-co-glycidyl methacrylate)

    SciTech Connect

    Warangkhana, Phromma; Rathanawan, Magaraphan; Jana Sadhan, C.

    2015-05-22

    The ternary blends of poly(lactic acid) (PLA), poly(ethylene-co-vinyl alcohol) (EVOH), and poly(ethylene-co-glycidyl methacrylate) (EGMA) were prepared. The role of EGMA as a compatibilizer was evaluated. The weight ratio of PLA:EVOH was 80:20 and the EGMA loadings were varied from 5-20 phr. The blends were characterized as follows: thermal properties by differential scanning calorimetry, morphology by scanning electron microscopy, and mechanical properties by pendulum impact tester, and universal testing machine. The glass transition temperature of PLA blends did not change much when compared with that of PLA. The blends of PLA/EGMA and EVOH/EGMA showed EGMA dispersed droplets where the latter led to poor impact properties. However, the tensile elongation at break and tensile toughness substantially increased upon addition of EGMA to blends of PLA and EVOH. It was noted in tensile test samples that both PLA and EVOH domains fibrillated significantly to produce toughness.

  12. Rheological behavior of poly(lactic acid)/synthetic mica nanocomposites.

    PubMed

    Souza, D H S; Andrade, C T; Dias, M L

    2013-04-01

    Poly(lactic acid) nanocomposites were prepared with three synthetic fluoromicas in a twin-screw extruder. Sodium and two organomodified synthetic fluoromicas at different compositions were used. The effect of mica type and composition on the rheological behavior of the nanocomposites was evaluated. The sodium fluoromica did not have a significant effect on the poly(lactic acid) rheological properties, while addition of the organophilic micas to poly(lactic acid) has a strong effect on the rheology, showing a pronounced shear thinning behavior. The dynamic rheological studies revealed that the nanocomposites with organomica have a higher viscosity and more pronounced elastic properties than neat poly(lactic acid). Both storage and loss moduli increased with mica content.

  13. Antiviral resistance by the polyinosinic acid-poly (1-vinylcytosine) complex.

    PubMed

    Pitha, J; Pitha, P M

    1971-06-11

    The antiviral activities of analogs of the double-stranded complex of polyinosinic and polycytidylic acids [poly(I).poly(C)], which is a potent interferon inducer, have been studied. Structural changes that modify the polymer backbone substantially, such as loops or 2' --> 5' phosphodiester bonds, lead to decreased antiviral activity. Unexpectedly, however, the complex of polyinosinic acid and poly(1-vinylcytosine), which is only a much more distantly related analog of poly(I) . poly(C), shows high activity. It is postulated that the high activity is related to the reduction of the charge/mass ratio and to the existence of this complex in an aggregated state; these are two factors that generally enhance the uptake of compo unds by cells.

  14. Effect of peroxide and chain extender on mechanical properties and morphology of poly (butylene succinate)/poly (lactic acid) blends

    NASA Astrophysics Data System (ADS)

    Cherykhunthod, W.; Seadan, M.; Suttiruengwong, S.

    2015-07-01

    Poly (butylene succinate) (PBS) and poly (lactic acid) (PLA) are biodegradable polymers with high potential to replace commodity fossil-based polymers in a wide range of applications. However, these two polymers are immiscible in most ratios, but partially miscible when one of the two is a major phase. In this study, a one-step process in a twin-screw extruder was used to prepare the blends between poly (butylene succinate) (PBS) as a matrix and poly (lactic acid) (PLA) as a dispersed phase. To improve mechanical properties and morphology of blends, two reactive agents, peroxide (Perkadox) and multifunctional epoxide chain extender (Joncryl) were selected and compared. All samples were characterized for melt flow index (MFI), morphology, tensile, and impact properties. The results showed that the mechanical properties and morphology of PBS/PLA blends were improved when using both reactive agents. It was demonstrated that the increased mechanical properties resulted from good interfacial adhesion between PBS and finely dispersed PLA particles. The addition of 0.075 phr Perkadox to PBS/PLA (75:25 and 80:20) blends increased elongation at break by 7.2% and 38.4%, respectively compared with the blends without reactive agents. The results from gel content also revealed the graft copolymer existed at the interface when reactive agents were added. In the case of using multifunctional epoxide chain extender, the impact strength of the blends increased.

  15. Poly(citric acid)-block-poly(ethylene glycol) copolymers--new biocompatible hybrid materials for nanomedicine.

    PubMed

    Naeini, Ashkan Tavakoli; Adeli, Mohsen; Vossoughi, Manouchehr

    2010-08-01

    Linear-dendritic ABA triblock copolymers containing poly(ethylene glycol) (PEG) as B block and hyperbranched poly(citric acid) (PCA) as A blocks were synthesized through polycondensation. The molecular self-assembly of synthesized PCA-PEG-PCA copolymers in water led to formation of nanoparticles and fibers in different sizes and shapes depending on the time and size of PCA blocks. Ten days after dissolving PCA-PEG-PCA copolymers in water, the size of fibers had reached several millimeters. Mixing a water solution of fluorescein as a small guest molecule and PCA-PEG-PCA copolymers led to the encapsulation of fluorescein by products of molecular self-assembly. To investigate their potential application in nanomedicine and to understand the limitations and capabilities of these materials as nanoexcipients in biological systems, different types of short-term in vitro cytotoxicity experiments on the HT1080 cell line (human fibrosarcoma) and hemocompatibility tests were performed. From the clinical editor: This manuscript investigates the potentials of linear-dendritic ABA triblock copolymers containing poly(ethylene glycol) (PEG) as B block and hyperbranched poly(citric acid) (PCA) as A blocks for future applications in nanomedicine.

  16. Sophorolipid-derived unsaturated and epoxy fatty acid estolides as plasticizers for poly(3-hydroxybutyrate)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Unsaturated and epoxy fatty acid estolides were synthesized from the omega and omega-1 hydroxy fatty acids derived from sophorolipids (SLs) prepared by fermentation from glucose:soybean oil and glucose:oleic acid, respectively. These estolides were utilized as additives in solution-cast poly(3-hydro...

  17. pH responsive poly amino-acid hydrogels formed via silk sericin templating.

    PubMed

    Kurland, Nicholas E; Ragland, Robert B; Zhang, Aolin; Moustafa, Mahmoud E; Kundu, Subhas C; Yadavalli, Vamsi K

    2014-09-01

    Poly(amino acid) hydrogels have attracted a great deal of attention as biodegradable biomaterials that can limit products of synthetic polymer degradation. Here we report on a stimuli-responsive, porous, composite biomaterial based on the protein templating of the poly(amino acid) hydrogel from poly(aspartic acid) with the silk protein sericin. This low-cost, biocompatible and biodegradable hydrogel demonstrates a greatly increased porosity and improvement in volumetric swelling over networks formed from pure poly(aspartic acid). The swelling capacity measured over a range of pH values surrounding physiological pH 7.0 demonstrates a linear profile, in which hydrogel volume and mass increase to a maximum, with an increase as a function of higher sericin content. In comparison to pure poly(aspartic acid), this demonstrates a nearly 3-fold increase in retention volume at basic pH. The increase in swelling is also demonstrated by the increase in porosity and internal micro-architecture of the hydrogel networks. The biomaterial is then shown to perform well as a scaffold for cells with high mechanical strength and integrity. This protein- and homo poly(amino acid)-based super-swelling hydrogel has applications in drug delivery and tissue engineering as an economical and environmentally friendly biomaterial, in addition to ensuring the species incorporated maintain their biocompatibility during processing.

  18. Miscibility and in vitro osteocompatibility of biodegradable blends of poly[(ethyl alanato) (p-phenyl phenoxy) phosphazene] and poly(lactic acid-glycolic acid)

    PubMed Central

    Deng, Meng; Nair, Lakshmi S.; Nukavarapu, Syam P.; Kumbar, Sangamesh G.; Jiang, Tao; Krogman, Nicholas R.; Singh, Anurima; Allcock, Harry R.; Laurencin, Cato T.

    2007-01-01

    Previously we demonstrated the ability of ethyl glycinato substituted polyphosphazenes to neutralize the acidic degradation products and control the degradation rate of poly(lactic acid-glycolic acid) by blending. In this study, blends of high strength poly[(50% ethyl alanato) (50% p-phenyl phenoxy) phosphazene] (PNEA50PhPh50) and 85:15 poly(lactic acid-glycolic acid) (PLAGA) were prepared using a mutual solvent approach. Three different solvents, methylene chloride (MC), chloroform (CF) and tetrahydrofuran (THF) were studied to investigate solvent effects on blend miscibility. Three different blends were then fabricated at various weight ratios namely 25:75 (BLEND25), 50:50 (BLEND50), and 75:25 (BLEND75) using THF as the mutual solvent. The miscibility of the blends was evaluated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). Among these, BLEND25 was miscible while BLEND50 and BLEND75 were partially miscible. Furthermore, BLEND25 formed apatite layers on its surface as evidenced in a biomimetic study performed. These novel blends showed cell adhesion and proliferation comparable to PLAGA. However, the PNEA50PhPh50 component in the blends was able to increase the phenotypic expression and mineralized matrix synthesis of the primary rat osteoblasts (PRO) in vitro. Blends of high strength poly[(50% ethyl alanato) (50% p-phenyl phenoxy) phosphazene] (PNEA50PhPh50) and 85:15 poly(lactic acid-glycolic acid) (PLAGA) are promising biomaterials for a variety of musculoskeletal applications. PMID:17942150

  19. Rapid IC-ICP/MS method for simultaneous analysis of iodoacetic acids, bromoacetic acids, bromate, and other related halogenated compounds in water.

    PubMed

    Shi, Honglan; Adams, Craig

    2009-07-15

    Haloacetic acids (HAAs) and bromate are toxic water disinfection by-products (DBPs) that the U.S. Environmental Protection Agency has regulated in drinking water. Iodoacetic acids (IAAs) are the emerging DBPs that have been recently found in disinfected drinking waters with higher toxicity than their corresponding chloro- and bromo-acetic acids. This study has developed a new rapid and sensitive method for simultaneous analysis of six brominated and four iodinated acetic acids, bromate, iodate, bromide, and iodide using ion chromatography-inductively coupled plasma-mass spectrometry (IC-ICP-MS). Mono-, di- and tri-chloroacetic acids are not detected by this method because the sensitivity of ICP-MS analysis for chlorine is poor. Following IC separation, an Elan DRC-e ICP-MS was used for detection, with quantitation utilizing m/z of 79, 127, and 74 amu for Br, I, and Ge (optional internal standard) species, respectively. Although the primary method used was an external standard procedure, an internal standard method approach is discussed herein as well. Calibration and validation were done in a variety of natural and disinfection-treated water samples. The method detection limits (MDLs) in natural water ranged from 0.33 to 0.72 microg L(-1) for iodine species, and from 1.36 to 3.28 microg L(-1) for bromine species. Spiked recoveries were between 67% and 123%, while relative standard deviations ranged from 0.2% to 12.8% for replicate samples. This method was applied to detect the bromine and iodine species in drinking water, groundwater, surface water, and swimming pool water.

  20. Magnesium phenylphosphonate: a additive for poly(L-lactic acid)

    NASA Astrophysics Data System (ADS)

    Cai, Yan-Hua; Zhao, Li-Sha

    2017-03-01

    Developing a advanced additive to promote the crystallization of poly(L-lactic acid) (PLLA) is still one of the main challenges for application. Here, magnesium phenylphosphonate (MgP), as a heterogeneous nucleating agent, was prepared to investigate directly its influence on the crystallization behavior and thermal stability of PLLA via a combination of differential scanning calorimetry (DSC), x-ray diffraction (XRD), and thermogravimetric analysis (TGA). The relevant results, from measurements of non-isothermal crystallization, the glass transition temperature, and XRD after melt crystallization, revealed that the MgP had excellent acceleration effectiveness in the melt crystallization of PLLA, and PLLA–0.7% MgP exhibited the sharpest non-isothermal crystallization peak and the highest non-isothermal crystallization enthalpy, suggesting that 0.7 wt% MgP is the optimal concentration in the PLLA matrix. In addition, these measurements also indicated that the incorporation of MgP could not change the crystal form of PLLA, and the non-isothermal crystallization behavior of PLLA–0.7% MgP did not have a significant relationship with the set final melting temperature. The melting behavior after non-isothermal crystallization further confirmed the crystallization-promoting effect of MgP for PLLA, and the second heating rate significantly affected the melting behavior of PLLA–MgP samples, resulting from the effect of heating rate on formation of crystallites. Thermal stability measurement showed that the addition of MgP could not change the thermal decomposition behavior of the primary PLLA, though MgP exhibited completely different thermal decomposition behavior. Furthermore, the influence of MgP concentration on the thermal decomposition temperatures of PLLA–MgP samples is negligible.

  1. Hemocompatibility of Chitosan/poly(acrylic acid) Grafted Polyurethane Tubing

    PubMed Central

    Lee, Hyun-Su; Tomczyk, Nancy; Kandel, Judith; Composto, Russell J.; Eckmann, David M.

    2013-01-01

    The activation and adhesion of platelets or whole blood exposed to chitosan (CH) grafted surfaces is used to evaluate the hemocompatibility of biomaterials. The biomaterial surfaces are polyurethane (PU) tubes grafted with an inner poly(acrylic acid) (PAA) and an outer CH or quaternary ammonium modified CH (CH-Q) brush. The CH, CH-Q and PAA grafted layers were characterized by ellipsometry and fluorescence microscopy. Material wear tests demonstrate that CH (CH-Q) is stably grafted onto PU tubes upon exposure to saline solution for 7 days. Using quartz-crystal microbalances with dissipation (QCM-D), in-situ adsorption of blood plasma proteins on CH and CH-Q compared to a silicon oxide control was measured. The QCM-D results showed that the physically adsorbed plasma protein layer on CH-Q and CH surfaces is softer and more viscous than the protein layer on the SiO2 surface. The CH-Q layer thus has the weakest interaction with plasma proteins. Whole blood and platelet adhesion was reduced by ~92% on CH-Q, which showed the weakest interaction with plasma protein but more viscous adsorbed plasma protein layer, compared to SiO2. Last, to examine the biologic response of platelets and neutrophils to biomaterial surfaces, CH (CH-Q)/PAA, PAA and PU tubes were tested using a Chandler Loop apparatus as an ex vivo model and flow cytometry. The blood adhesion and biologic response results showed that CH and CH-Q reduced adhesion and activation of platelets and neutrophils and improved hemocompatibility relative to other surfaces (PU and PAA). Our studies demonstrated that the properties of physically adsorbed plasma protein layer on biomaterial surfaces correlates with blood coagulation on biomaterial surfaces. PMID:24349719

  2. Poly(carbonate–amide)s Derived from Bio-Based Resources: Poly(ferulic acid-co-tyrosine)

    PubMed Central

    2015-01-01

    Ferulic acid (FA), a bio-based resource found in fruits and vegetables, was coupled with a hydroxyl-amino acid to generate a new class of monomers to afford poly(carbonate–amide)s with potential to degrade into natural products. l-Serine was first selected as the hydroxyl-amino partner for FA, from which the activated p-nitrophenyl carbonate monomer was synthesized. Unfortunately, polymerizations were unsuccessful, and the elimination product was systematically obtained. To avoid elimination, we revised our strategy and used l-tyrosine ethyl ester, which lacks an acidic proton on the α position of the ethyl ester. Four new monomers were synthesized and converted into the corresponding poly(carbonate–amide)s with specific regioselectivities. The polymers were fully characterized through thermal and spectroscopic analyses. Preliminary fluorescent studies revealed interesting photophysical properties for the monomers and their corresponding poly(carbonate–amide)s, beyond the fluorescence characteristics of l-tyrosine and FA, making these materials potentially viable for sensing and/or imaging applications, in addition to their attractiveness as engineering materials derived from renewable resources. PMID:24839309

  3. Vaccine Adjuvants in Fish Vaccines Make a Difference: Comparing Three Adjuvants (Montanide ISA763A Oil, CpG/Poly I:C Combo and VHSV Glycoprotein) Alone or in Combination Formulated with an Inactivated Whole Salmonid Alphavirus Antigen.

    PubMed

    Thim, Hanna L; Villoing, Stéphane; McLoughlin, Marian; Christie, Karen Elina; Grove, Søren; Frost, Petter; Jørgensen, Jorunn B

    2014-03-25

    Most commercial vaccines offered to the aquaculture industry include inactivated antigens (Ag) formulated in oil adjuvants. Safety concerns are related to the use of oil adjuvants in multivalent vaccines for fish, since adverse side effects (e.g., adhesions) can appear. Therefore, there is a request for vaccine formulations for which protection will be maintained or improved, while the risk of side effects is reduced. Here, by using an inactivated salmonid alphavirus (SAV) as the test Ag, the combined use of two Toll-like receptor (TLR) ligand adjuvants, CpG oligonucleotides (ODNs) and poly I:C, as well as a genetic adjuvant consisting of a DNA plasmid vector expressing the viral haemorrhagic septicaemia virus (VHSV) glycoprotein (G) was explored. VHSV-G DNA vaccine was intramuscularly injected in combination with intraperitoneal injection of either SAV Ag alone or combined with the oil adjuvant, Montanide ISA763, or the CpG/polyI:C combo. Adjuvant formulations were evaluated for their ability to boost immune responses and induce protection against SAV in Atlantic salmon, following cohabitation challenge. It was observed that CpG/polyI:C-based formulations generated the highest neutralizing antibody titres (nAbs) before challenge, which endured post challenge. nAb responses for VHSV G-DNA- and oil-adjuvanted formulations were marginal compared to the CpG/poly I:C treatment. Interestingly, heat-inactivated sera showed reduced nAb titres compared to their non-heated counterparts, which suggests a role of complement-mediated neutralization against SAV. Consistently elevated levels of innate antiviral immune genes in the CpG/polyI:C injected groups suggested a role of IFN-mediated responses. Co-delivery of the VHSV-G DNA construct with either CpG/polyI:C or oil-adjuvanted SAV vaccine generated higher CD4 responses in head kidney at 48 h compared to injection of this vector or SAV Ag alone. The results demonstrate that a combination of pattern recognizing receptor (PRR

  4. Vaccine Adjuvants in Fish Vaccines Make a Difference: Comparing Three Adjuvants (Montanide ISA763A Oil, CpG/Poly I:C Combo and VHSV Glycoprotein) Alone or in Combination Formulated with an Inactivated Whole Salmonid Alphavirus Antigen

    PubMed Central

    Thim, Hanna L.; Villoing, Stéphane; McLoughlin, Marian; Christie, Karen Elina; Grove, Søren; Frost, Petter; Jørgensen, Jorunn B.

    2014-01-01

    Most commercial vaccines offered to the aquaculture industry include inactivated antigens (Ag) formulated in oil adjuvants. Safety concerns are related to the use of oil adjuvants in multivalent vaccines for fish, since adverse side effects (e.g., adhesions) can appear. Therefore, there is a request for vaccine formulations for which protection will be maintained or improved, while the risk of side effects is reduced. Here, by using an inactivated salmonid alphavirus (SAV) as the test Ag, the combined use of two Toll-like receptor (TLR) ligand adjuvants, CpG oligonucleotides (ODNs) and poly I:C, as well as a genetic adjuvant consisting of a DNA plasmid vector expressing the viral haemorrhagic septicaemia virus (VHSV) glycoprotein (G) was explored. VHSV-G DNA vaccine was intramuscularly injected in combination with intraperitoneal injection of either SAV Ag alone or combined with the oil adjuvant, Montanide ISA763, or the CpG/polyI:C combo. Adjuvant formulations were evaluated for their ability to boost immune responses and induce protection against SAV in Atlantic salmon, following cohabitation challenge. It was observed that CpG/polyI:C-based formulations generated the highest neutralizing antibody titres (nAbs) before challenge, which endured post challenge. nAb responses for VHSV G-DNA- and oil-adjuvanted formulations were marginal compared to the CpG/poly I:C treatment. Interestingly, heat-inactivated sera showed reduced nAb titres compared to their non-heated counterparts, which suggests a role of complement-mediated neutralization against SAV. Consistently elevated levels of innate antiviral immune genes in the CpG/polyI:C injected groups suggested a role of IFN-mediated responses. Co-delivery of the VHSV-G DNA construct with either CpG/polyI:C or oil-adjuvanted SAV vaccine generated higher CD4 responses in head kidney at 48 h compared to injection of this vector or SAV Ag alone. The results demonstrate that a combination of pattern recognizing receptor (PRR

  5. Biodegradation and Osteosarcoma Cell Cultivation on Poly(aspartic acid) Based Hydrogels.

    PubMed

    Juriga, Dávid; Nagy, Krisztina; Jedlovszky-Hajdú, Angéla; Perczel-Kovách, Katalin; Chen, Yong Mei; Varga, Gábor; Zrínyi, Miklós

    2016-09-14

    Development of novel biodegradable and biocompatible scaffold materials with optimal characteristics is important for both preclinical and clinical applications. The aim of the present study was to analyze the biodegradability of poly(aspartic acid)-based hydrogels, and to test their usability as scaffolds for MG-63 osteoblast-like cells. Poly(aspartic acid) was fabricated from poly(succinimide) and hydrogels were prepared using natural amines as cross-linkers (diaminobutane and cystamine). Disulfide bridges were cleaved to thiol groups and the polymer backbone was further modified with RGD sequence. Biodegradability of the hydrogels was evaluated by experiments on the base of enzymes and cell culture medium. Poly(aspartic acid) hydrogels possessing only disulfide bridges as cross-links proved to be degradable by collagenase I. The MG-63 cells showed healthy, fibroblast-like morphology on the double cross-linked and RGD modified hydrogels. Thiolated poly(aspartic acid) based hydrogels provide ideal conditions for adhesion, survival, proliferation, and migration of osteoblast-like cells. The highest viability was found on the thiolated PASP gels while the RGD motif had influence on compacted cluster formation of the cells. These biodegradable and biocompatible poly(aspartic acid)-based hydrogels are promising scaffolds for cell cultivation.

  6. Inherently antioxidant and antimicrobial tannic acid release from poly(tannic acid) nanoparticles with controllable degradability.

    PubMed

    Sahiner, Nurettin; Sagbas, Selin; Aktas, Nahit; Silan, Coskun

    2016-06-01

    From a natural polyphenol, Tannic acid (TA), poly(TA) nanoparticles were readily prepared using a single step approach with three different biocompatible crosslinkers; trimethylolpropane triglycidyl ether (TMPGDE), poly(ethylene glycol) diglycidyl ether (PEGGE), and trisodium trimetaphosphate (STMP). P(TA) particles were obtained with controllable diameters between 400 to 800nm with -25mV surface charge. The effect of synthesis conditions, such as the emulsion medium, pH values of TA solution, and the type of crosslinker, on the shape, size, dispersity, yield, and degradability of poly(Tannic Acid) (p(TA)) nanoparticles was systematically investigated. The hydrolytic degradation amount in physiological pH conditions of 5.4, 7.4, and 9.0 at 37.5°C were found to be in the order TMPGDE

  7. Methyl-branched poly(hydroxyalkanoate) biosynthesis from 13- methyltetradecanoic acid and mixed isostearic acid isomer substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas resinovorans, a known medium-chain-length (mcl-) poly(hydroxyalkanoate) (PHA) producer, was grown on 13-methyltetradecanoic acid (13-MTDA) and a mixture of isostearic acid (IA) isomers to produce methyl-branched mcl-PHA polymers. Shake flask experiments revealed polymer productivities (...

  8. Optimization of a biomimetic poly-(lactic acid) ligament scaffold

    NASA Astrophysics Data System (ADS)

    Uehlin, Andrew F.

    The anterior cruciate ligament (ACL) is the most commonly injured ligament of the knee, often requiring orthopedic reconstruction using autograft or allograph tissue, both with significant disadvantages. As a result, tissue engineering an ACL replacement graft has been heavily investigated. The present study attempts to replicate the morphology and mechanical properties of the ACL using a nanomatrix composite of highly-aligned poly(lactic acid) (PLA) fibers with various surface and biochemical modifications. Additionally, this study attempts to recreate the natural mineralization gradient found at the ACL enthesis onto the scaffold, capable of inducing a favorable cellular response in vitro. Unidirectional electrospinning was used to create nanofibers of PLA, followed by an induced degradation of the nanofibers via 0.25M NaOH hydrolysis. The effects of the unidirectional electrospinning as well as the effects of NaOH hydrolysis on fiber alignment, fiber diameter, surface morphology, crystallinity, in vitro swelling, immobilization of fibrin, and mechanical properties were investigated, resulting in a modified morphology correlating to the microstructure of native ligament tissue with similar mechanical properties. Furthering the development of the PLA nanomatrix composite, a bioinkjet printer was used to immobilize nanoparticulate hydroxyapatite (HANP) on the surface of the scaffold. A series of 300pL droplets of HANP bioink were printed over a gradient pattern mimetic of (and spatially corresponding to) the mineralization gradient found over the microanatomy at the ACL enthesis. Proliferation and differentiation response of human mesenchymal stem cells (hMSCs) in vitro was assessed on a variety of conditions and combinations of the PLA nanofiber scaffold surface modifications (inclusive and exclusive of HANP, fibrin, and various time dependent NaOH treatments). It was found that a combinatory effect of the HANP gradient with fibrin on 20 minute NaOH treated PLA

  9. Poly(vinyl alcohol)/poly(acrylic acid) hydrogel coatings for improving electrode-neural tissue interface.

    PubMed

    Lu, Yi; Wang, Dingfang; Li, Tao; Zhao, Xueqing; Cao, Yuliang; Yang, Hanxi; Duan, Yanwen Y

    2009-09-01

    A major problem which hinders the applications of neural prostheses is the inconsistent performance caused by tissue responses during long-term implantation. The study investigated a new approach for improving the electrode-neural tissue interface. Hydrogel poly(vinyl alcohol)/poly(acrylic acid) interpenetrating polymer networks (PVA/PAA IPNs) were synthesized and tailored as coatings for poly(dimethylsiloxane) (PDMS) based neural electrodes with the aid of plasma pretreatment. Changes in the electrochemical impedance and maximum charge injection (Q(inj)) limits of the coated iridium oxide microelectrodes were negligible. Protein adsorption on PDMS was reduced by approximately 85% after coating. In the presence of nerve growth factor (NGF), neurite extension of rat pheochromocytoma (PC12) cells was clearly greater on PVA/PAA IPN films than on PDMS substrates. Furthermore, the tissue responses of PDMS implants coated with PVA/PAA IPN films were studied by 6-week implantation in the cortex of rats, which found that the glial fibrillary acidic protein (GFAP) immunoreactivity in animals (n=8) receiving coated implants was significantly lower (p<0.05) compared to that of uncoated implants (n=7) along the entire distance of 150 microm from the outer skirt to the implant interface. The coated film remained on the surface of the explanted implants, confirmed by scanning electron microscopy (SEM). All of these suggest the hydrogel coating is feasible and favorable to neural electrode applications.

  10. Microencapsulation of lobster carotenoids within poly(vinyl alcohol) and poly(D,L-lactic acid) membranes.

    PubMed

    Sun, Z M; Poncelet, D; Conway, J; Neufeld, R J

    1995-01-01

    The use of natural pigments such as lobster carotenoids in fish feed formulations offers advantages over the use of the synthetic alternatives. Microencapsulation of the pigments, with or without the addition of antioxidants to the formulation, may be of benefit in terms of stabilizing pigment colour. In the present study, lobster carotenoids were extracted from lobster shell into petroleum ether and microencapsulated by phase separation and salt coacervation within (poly vinyl alcohol) and poly(vinyl alcohol)/poly(D,L-lactic acid) membranes. Spherical microcapsules, with smooth, thin and resilient membranes were obtained with mean diameters ranging from 50 to 150 microns, depending on the membrane material, and source of pigment. The microcapsules were pink-orange in colour, and colour stability was followed spectrophotometrically. Enhanced stability was observed in both membrane materials, in comparison to the non-encapsulated control. Rates of discoloration were determined under a variety of storage conditions, including the absence of light, reduced temperatures and under nitrogen atmosphere. The best stability of lobster carotenoids was observed under a nitrogen atmosphere within PVA/PLA membranes, representing an 11-fold enhancement of pigment stability in comparison to the controls. Under ambient conditions, the enhancement in pigment stability was approximately 6-fold. The optimum concentration of PVA during microencapsulation was 3-4%, and the microencapsulated pigments appeared most stable under acidic conditions. The rate of discoloration appeared independent of pigment concentration.

  11. Mucin/poly(acrylic acid) interactions: a spectroscopic investigation of mucoadhesion.

    PubMed

    Patel, Minesh M; Smart, John D; Nevell, Thomas G; Ewen, Richard J; Eaton, Peter J; Tsibouklis, John

    2003-01-01

    Studies using infrared, (1)H and (13)C nuclear magnetic resonance, and X-ray photoelectron spectroscopies and differential scanning calorimetry support the hypothesis that hydrogen bonds, formed between the carboxylic acid functionality of the mucoadhesive material poly(acrylic acid) and the glycoprotein component of mucus, play a significant role in the process of mucoadhesion. There are fewer H-bonded interactions between the components than within the bulk of the pure mucoadhesive agent. The pH of the medium influences the structures of both the poly(acrylic acid) and the mucus, which, in turn, determine the nature and the extent of mucoadhesive interactions.

  12. Physicochemical Properties and Applications of Poly(lactic-co-glycolic acid) for Use in Bone Regeneration

    PubMed Central

    Félix Lanao, Rosa P.; Jonker, Anika M.; Wolke, Joop G.C.; Jansen, John A.; van Hest, Jan C.M.

    2013-01-01

    Poly(lactic-co-glycolic acid) (PLGA) is the most often used synthetic polymer within the field of bone regeneration owing to its biocompatibility and biodegradability. As a consequence, a large number of medical devices comprising PLGA have been approved for clinical use in humans by the American Food and Drug Administration. As compared with the homopolymers of lactic acid poly(lactic acid) and poly(glycolic acid), the co-polymer PLGA is much more versatile with regard to the control over degradation rate. As a material for bone regeneration, the use of PLGA has been extensively studied for application and is included as either scaffolds, coatings, fibers, or micro- and nanospheres to meet various clinical requirements. PMID:23350707

  13. Polydopamine-coated electrospun poly(vinyl alcohol)/poly(acrylic acid) membranes as efficient dye adsorbent with good recyclability.

    PubMed

    Yan, Jiajie; Huang, Yunpeng; Miao, Yue-E; Tjiu, Weng Weei; Liu, Tianxi

    2015-01-01

    Free-standing poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) membranes with polydopamine (PDA) coating were prepared based on the combination of electrospinning and self-polymerization of dopamine. This is a facile, mild, controllable, and low-energy consumption process without any rigorous restriction to reactive conditions. Benefiting from the high specific surface area of electrospun membranes and the abundant "adhesive" functional groups of polydopamine, the as-prepared membranes exhibit efficient adsorption performance towards methyl blue with the adsorption capacity reaching up to 1147.6 mg g(-1). Moreover, compared to other nanoparticle adsorbents, the as-prepared self-standing membrane is highly flexible, easy to operate and retrieve, and most importantly, easy to elute, and regenerate, which enable its potential applications in wastewater treatment.

  14. Development of Conducting Polyaniline/ Poly(Lactic Acid) Nanofibers by Electrospinning

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ultrafine fibers consisting of blends of polyaniline doped with p-toluene sulfonic acid and poly(L-lactic acid) were prepared by electrospinning. The presence of polyaniline resulted in fibers with diameters as thin as 100– 200 nm and a significant reduction of bead formation. These fibers were visu...

  15. A multivariant study of the absorption properties of poly(glutaric-acid-glycerol) films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The solvent absorption into the matrix of poly(glutaric acid-glycerol) films made with or without either iminodiacetic acid, sugarcane bagasse, pectin, corn fiber gum or microcrystalline cellulose have been evaluated. The films were incubated in various solvent systems for 24h. The amounts of solve...

  16. Miscibility of poly(lactic acid) and poly(ethylene oxide) solvent polymer blends and nanofibers made by solution blow spinning

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The miscibility of blends of poly(lactic acid) (PLA) and poly(ethylene oxide) (PEO) was studied in polymer solutions by dilute solution viscometry and in solution blow spun nanofibers by microscopy (SEM, TEM) and by thermal and spectral analysis. Three blends of PLA and PEO were solution blended in...

  17. Self-Controlled Synthesis of Hyperbranched Poly(etherketone)s from A2 + B3 Approach in Poly(phosphoric acid)

    DTIC Science & Technology

    2009-01-01

    polymerization condition was indeed strong enough to effi- ciently facilitate polycondensation via ‘‘direct’’ Friedel - Crafts reaction without gelation...Keywords: Friedel - Crafts acylation; high performance polymer; hyperbranched polymer; poly(ether-ketone)s; poly(phosphoric acid) INTRODUCTION Dendritic...Hence, the applied polymerization condition was indeed strong enough to efficiently facilitate polycondensation via ??direct?? Friedel - Crafts reaction

  18. Modification of poly(L-lactic acid) electrospun fibers and films with poly(propylene imine) dendrimer

    NASA Astrophysics Data System (ADS)

    Khaliliazar, Sh.; Akbari, S.; Kish, M. H.

    2016-02-01

    Poly(L-lactic acid) (PLLA) electrospun fibers and films were modified with the second generation of poly(propylene imine) dendrimer (PPI-G2) by three different approaches, namely, sodium hydroxide hydrolysis, plasma treatment and direct application of PPI-G2. For the first and the second approaches, PLLA was modified by sodium hydroxide hydrolysis or plasma treatment to produce carboxylic acid groups. Then, the carboxylic acid groups were activated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) and N,N‧-dicyclohexyl carbodiimide (DCC) as a hetero bi-functional cross-linker. The cross-linkers promoted the grafting of carboxylic acid groups on the modified PLLA with NH2 groups of PPI-G2. In the third approach, the PPI-G2 dendrimer was directly used as an aminolysis agent for the functionalization of PLLA in a one step process. FTIR analysis confirmed the presence of sbnd NH2 groups of PPI-G2 on the modified PLLA samples, resulting from each one of the three modification methods. Studies by SEM shows bead free electrospun fibers. Also, FE-SEM shows nano-cracks on the surface of films after modification. Contact angle, drug release tests, antibacterial effects and the dying results confirmed that these functionalization methods increased hydrophilicity and reactive side-chains of PLLA in the wet chemical process resulted in providing host-guest properties on the PLLA surface for adsorbing various kinds of guest molecules.

  19. Viscoelasticity of repaired sciatic nerve by poly(lactic-co-glycolic acid) tubes.

    PubMed

    Piao, Chengdong; Li, Peng; Liu, Guangyao; Yang, Kun

    2013-11-25

    Medical-grade synthetic poly(lactic-co-glycolic acid) polymer can be used as a biomaterial for nerve repair because of its good biocompatibility, biodegradability and adjustable degradation rate. The stress relaxation and creep properties of peripheral nerve can be greatly improved by repair with poly(lactic-co-glycolic acid) tubes. Ten sciatic nerve specimens were harvested from fresh corpses within 24 hours of death, and were prepared into sciatic nerve injury models by creating a 10 mm defect in each specimen. Defects were repaired by anastomosis with nerve autografts and poly(lactic-co-glycolic acid) tubes. Stress relaxation and creep testing showed that at 7 200 seconds, the sciatic nerve anastomosed by poly(lactic-co-glycolic acid) tubes exhibited a greater decrease in stress and increase in strain than those anastomosed by nerve autografts. These findings suggest that poly(lactic-co-glycolic acid) exhibits good viscoelasticity to meet the biomechanical require-ments for a biomaterial used to repair sciatic nerve injury.

  20. Utilizing acid pretreatment and electrospinning to improve biocompatibility of poly(glycolic acid) for tissue engineering.

    PubMed

    Boland, Eugene D; Telemeco, Todd A; Simpson, David G; Wnek, Gary E; Bowlin, Gary L

    2004-10-15

    Poly(glycolic acid) (PGA) has a long history as a bioresorbable polymer. Its biocompatibility is widely accepted, yet PGA is often rejected as a soft-tissue scaffold because of fibrous encapsulation. The goal of this study was to improve the soft-tissue biocompatibility of PGA by producing scaffolds composed of small-diameter fibers through electrospinning and subjecting these scaffolds to a concentrated hydrochloric acid (HCL) pretreatment. The theory is that small-diameter fibers will elicit a reduced immune response and HCl treatment will improve cellular interactions. Scaffolds were characterized in terms of fiber diameter and pore area via image-analysis software. Biocompatibility was assessed through a WST-1 cell-proliferation assay (in vitro) with the use of rat cardiac fibroblasts and rat intramuscular implantations (in vivo). Fibers produced ranged in diameter from 0.22 to 0.88 microm with pore areas from 1.84 to 13.22 microm(2). The untreated scaffold composed of 0.88-microm fibers was encapsulated in vivo and supported the lowest rates of cell proliferation. On the contrary, the acid pretreated scaffold with 0.22-microm fibers was incorporated into the surrounding tissue and exhibited proliferation rates that exceeded the control populations on tissue-culture plastic. In conclusion, this study has shown the ability to improve the biocompatibility of PGA through acid pretreatment of scaffolds comprised of submicron fiber diameters.

  1. IC Treatment: Antidepressants

    MedlinePlus

    ... a “black box warning” regarding the potential for suicide and suicidal thinking in children and adolescents taking ... Flares Women & IC Pregnancy & IC Intimacy & IC Pelvic Exam Tips Men & IC Intimacy & IC Support for Men ...

  2. Functional genomic analysis of the response of Atlantic cod (Gadus morhua) spleen to the viral mimic polyriboinosinic polyribocytidylic acid (pIC).

    PubMed

    Rise, Matthew L; Hall, Jennifer; Rise, Marlies; Hori, Tiago; Gamperl, A Kurt; Kimball, Jennifer; Hubert, Sophie; Bowman, Sharen; Johnson, Stewart C

    2008-01-01

    In order to improve our understanding of how Atlantic cod (Gadus morhua) respond to viruses, we characterized immune-related gene expression in spleen tissues following stimulation with a synthetic double-stranded RNA polyriboinosinic polyribocytidylic acid (pIC). We used reciprocal suppression subtractive hybridization (SSH) cDNA libraries and quantitative RTPCR (QPCR) to identify and quantify pIC-responsive transcripts. A total of 3874 expressed sequence tags (ESTs) were generated from SSH libraries enriched for genes responsive to pIC. Thirteen immune-relevant genes from the libraries were subjected to QPCR. Genes confirmed as up-regulated by pIC included interferon stimulated gene 15, a small inducible cytokine, interferon regulatory factors (1, 7, and 10), MHC class I, viperin, and ATP-dependent helicase LGP2. Alpha-1-microglobulin (bikunin) was down-regulated, suggesting that pIC may suppress the acute phase response. Since the SSH libraries built for this study identified genes involved in the antiviral response, they are important resources for studying the responses of Atlantic cod to viruses. Evidence is provided for the existence of a RIG-I-like RNA helicase viral recognition pathway in Atlantic cod. Taken together, our data show that Atlantic cod can recognize double-stranded RNA and mount a rapid and potent interferon pathway response that is similar to that observed in other fish species and higher vertebrates.

  3. Improved neutralising antibody response against foot-and-mouth-disease virus in mice inoculated with a multi-epitope peptide vaccine using polyinosinic and poly-cytidylic acid as an adjuvant.

    PubMed

    Cao, Yimei; Lu, Zengjun; Li, Pinghua; Sun, Pu; Fu, Yuanfang; Bai, Xingwen; Bao, Huifang; Chen, Yingli; Li, Dong; Liu, Zaixin

    2012-10-01

    A peptide-based vaccine for foot-and-mouth disease (FMD) was designed. The peptide immunogen had a G-H loop domain optimised for immunogenicity and broad-spectrum antigenicity to different lineages of serotype-O FMD viruses (FMDVs). Polyinosinic and poly-cytidylic acid [poly (I:C)] was used as the adjuvant to overcome the low humoral antibody levels often observed in association with peptide-based vaccines. The multi-epitope peptide alone induced the secretion of a certain level of neutralising antibodies in mice. In contrast, co-administration of the multi-epitope peptide with poly (I:C) induced the secretion of a significantly higher level of neutralising antibodies (P<0.005). Indeed, the resultant level was slightly higher even than that induced by the inactivated vaccine (P>0.05). These initial results indicate that poly (I:C) is highly effective as an adjuvant for use with the FMDV multi-epitope peptide vaccine. This combination could yield a promising vaccine for the prevention and control of FMD. Further study is needed to evaluate the efficiency of this combination on animals susceptible naturally to FMDV.

  4. Effect of an acid filler on hydrolysis and biodegradation of poly-lactic acid (PLA)

    NASA Astrophysics Data System (ADS)

    Iozzino, Valentina; Speranza, Vito; Pantani, Roberto

    2015-12-01

    The use of biodegradable polymers is certainly an excellent strategy to solve many of the problems related to the disposal of the traditional polymers, whose accumulation in the environment is harmful and damaging. In order to optimize the use of biodegradable polymers, it is very important to understand and control the transformation processes, the structures and the morphologies resulting from the process conditions used to produce the articles and, not least, the biodegradation. The latter is strictly dependent on the just mentioned variables. The poly-lactic acid, PLA, is a biodegradable polymer. Many studies have been carried out on the degradation process of this polymer. In the course of this work we performed degradation tests on the PLA, with a specific D-isomer content, having amorphous structure, and in particular of biodegradation and hydrolysis. An acid chemical, fumaric acid, was added to PLA with the objective of controlling the rate of hydrolysis and of biodegradation. The hydrolysis process was followed, as function of time, by means of different techniques: pH variation, variation of weight of samples and variation of crystallinity degree and glass transition temperature using DSC analysis. The samples were also analyzed in terms of biodegradability by means of a homemade respirometer apparatus, in controlled composting conditions.

  5. Protein purification with polymeric affinity membranes containing functionalized poly(acid) brushes.

    PubMed

    Jain, Parul; Vyas, Mukesh Kumar; Geiger, James H; Baker, Gregory L; Bruening, Merlin L

    2010-04-12

    Porous nylon membranes modified with poly(acid) brushes and their derivatives can rapidly purify proteins via ion-exchange and metal-ion affinity interactions. Membranes containing poly(2-(methacryloyloxy)ethyl succinate) (poly(MES)) brushes bind 118 +/- 8 mg of lysozyme per cm(3) of membrane and facilitate purification of lysozyme from chicken egg white. Moreover, functionalization of the poly(MES) brushes with nitrilotriacetate (NTA)-Ni(2+) complexes yields membranes that bind poly(histidine)-tagged (His-tagged) ubiquitin with a capacity of 85 +/- 2 mg of protein per cm(3) of membrane. Most importantly, the membranes modified with poly(MES)-NTA-Ni(2+) allow isolation of His-tagged cellular retinaldehyde-binding protein directly from a cell extract in <10 min, and the protein purity is comparable to that achieved with commercial affinity columns. Therefore, porous nylon membranes containing functionalized poly(MES) brushes are attractive candidates for rapid, high-capacity purification of His-tagged proteins from cell extracts.

  6. Adhesion of a fluorinated poly(amic acid) with stainless steel surfaces

    NASA Astrophysics Data System (ADS)

    Jung, Youngsuk; Song, Sunjin; Kim, Sangmo; Yang, Yooseong; Chae, Jungha; Park, Tai-Gyoo; Dong Cho, Myung

    2013-01-01

    The authors elucidate an origin and probable mechanism of adhesion strength change at an interface of fluorinated poly(amic acid) and stainless steel. Fluorination provides favorable delamination with release strength weaker than 0.08 N/mm from a metal surface, once the amount of residual solvent becomes less than 35 wt. %. However, the release strength critically depends on film drying temperature. Characterization on stainless steel surfaces and thermodynamic analyses on wet films reveal a drying temperature of 80 °C fosters interaction between the metal oxides at stainless steel surface and the free electron donating groups in poly(amic acid).

  7. Fluorescence decay studies of poly(riboadenylic acid) containing 1-N6-ethenoadenosine.

    PubMed

    Kubota, Y; Sanjoh, A; Fujisaki, Y; Steiner, R F

    1983-10-01

    The fluorescence properties of the 1-N6-etheno derivatives of poly(riboadenylic acid) (poly(rA, epsilon rA)) have been examined. The fluorescence quantum yield of poly(rA, epsilon rA) decreases with an increase in the degree of the epsilon A substitution and is much smaller than that for epsilon AMP even for low degrees of epsilon A substitution. The nearest-neighbor interactions such as epsilon-adenine-adenine and epsilon-adenine-epsilon-adenine may be responsible for this behavior. It is found that the fluorescence decay kinetics obeys a three-exponential decay law for poly(rA, epsilon rA), suggesting that there exist at least three different stacked conformational states.

  8. An IC-MS/MS Method for the Determination of 1-Hydroxyethylidene-1,1-diphosphonic Acid on Uncooked Foods Treated with Peracetic Acid-Based Sanitizers.

    PubMed

    Suzuki, Ippei; Kubota, Hiroki; Ohtsuki, Takashi; Tatebe, Chiye; Tada, Atsuko; Yano, Takeo; Akiyama, Hiroshi; Sato, Kyoko

    2016-01-01

    A rapid, sensitive, and specific analytical method for the determination of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) on uncooked foods after treatment with a peracetic acid-based sanitizer (PAS) was developed. The method involves simple sample preparation steps and analysis using ion chromatography (IC) coupled with tandem mass spectrometry (MS/MS). The quantification limits of HEDP on uncooked foods are 0.007 mg/kg for vegetables and fruits and 0.2 mg/kg for meats. The recovery and relative standard deviation (RSD) of HEDP analyses of uncooked foods ranged from 73.9 to 103.8% and 1.9 to 12.6%, respectively. The method's accuracy and precision were evaluated by inter-day recovery tests. The recovery for all samples ranged from 93.6 to 101.2%, and the within-laboratory repeatability and reproducibility were evaluated based on RSD values, which were less than 6.9 and 11.5%, respectively. Analyses of PAS-treated fruits and vegetables using the developed method indicated levels of HEDP ranging from 0.008 to 0.351 mg/kg. Therefore, the results of the present study suggest that the proposed method is an accurate, precise, and reliable way to determine residual HEDP levels on PAS-treated uncooked foods.

  9. Technique paper for wet-spinning poly(L-lactic acid) and poly(DL-lactide-co-glycolide) monofilament fibers.

    PubMed

    Nelson, Kevin D; Romero, Andres; Waggoner, Paula; Crow, Brent; Borneman, Angela; Smith, George M

    2003-12-01

    A simple and repeatable method is described for wet-spinning poly(L-lactic acid) (PLLA) and poly(DL-lactic-co-glycolic acid) (PLGA) monofilament fibers. These fibers are strong, elastic, and suitable for many applications, including use as tissue-engineering scaffolds. The PLLA wet-extruded fibers do not show additional strain-induced crystallization as a result of drawing the fibers during fabrication; however, there is an apparent increase in crystallinity late in the degradation process in saline at 37 degrees C. We have measured the molecular weight degradation in saline at 37 degrees C for fibers of both PLLA and PLGA. Changing solvent systems, polymer blends, and winding rates alters mechanical and morphological properties of these fibers for specific applications. The authors discuss a possible theoretical explanation for these observed changes due to changes in polymer concentration, solvent system, and coagulation bath properties. This wet-extrusion process is simple and inexpensive enough to be carried out in almost any laboratory interested in tissue engineering.

  10. Grafting of cellulose fibers with poly(epsilon-caprolactone) and poly(L-lactic acid) via ring-opening polymerization.

    PubMed

    Lönnberg, Hanna; Zhou, Qi; Brumer, Harry; Teeri, Tuula T; Malmström, Eva; Hult, Anders

    2006-07-01

    In this study, ring-opening polymerization (ROP) of epsilon-caprolactone (epsilon-CL) and L-lactide (L-LA) has been performed from cellulose fibers. The hydroxyl groups on cellulose act as initiators in the polymerization, and the polymers are covalently bonded to the cellulose fiber. As an attempt to introduce more available hydroxyl groups on the surface, and thereby obtain higher grafting efficiency in the ROP of epsilon-CL and L-LA, unmodified paper was modified with xyloglucan-bis(methylol)-2-methylpropanamide (XG-bis-MPA) and 2,2-bis(methylol)propionic acid (bis-MPA), respectively. The grafted substrates were characterized via Fourier transform infrared spectroscopy (FTIR), contact angle measurement, atomic force microscopy, and enzymatic degradation. The results showed a successful grafting of poly(epsilon-caprolactone) (PCL) and poly(L-lactic acid) (PLLA) from the cellulose fiber surfaces. Furthermore, the results showed an improved grafting efficiency after activation of the cellulose surface with bis-MPA, and showed that the amount of grafted polymer could be controlled by the ratio of added free initiator to monomer.

  11. Effect of the photoreaction solvent on surface and bulk properties of poly(lactic acid) and poly(hydroxyalkanoate) films.

    PubMed

    Rasal, Rahul M; Bohannon, Bradley G; Hirt, Douglas E

    2008-05-01

    The major objective of this research was to modify the surface properties of poly(lactic acid) (PLA) and poly(hydroxyalkanoate) (PHA) films by using a sequential two-step photografting approach. In step 1, benzophenone was photografted on the film surface and in step 2, hydrophilic monomers acrylamide and acrylic acid were photopolymerized from the film surfaces. Another objective was to study the effect of the reaction solvent in step 2 on surface and bulk properties of these films. ATR-FTIR spectroscopy and water contact angle goniometry were used to characterize the resultant film surfaces. When ethanol was used as the solvent in step 2, there was significant penetration of the monomers into the films, and bulk properties such as toughness and percent elongation at break were drastically affected. The penetration of these monomers into the bulk was characterized using transmission FTIR microspectroscopy. Microtomed sections of the surface-modified films were placed in a diamond compression cell to perform the FTIR microspectroscopic analyses. The observed monomer penetration into the films was successfully reduced by using water instead of ethanol in step 2, and resultant films showed higher toughness and percent elongation at break than films surface-modified using ethanol as a solvent in step 2.

  12. Systematic unravelling of the biosynthesis of poly (L-diaminopropionic acid) in Streptomyces albulus PD-1

    PubMed Central

    Xu, Zhaoxian; Sun, Zhuzhen; Li, Sha; Xu, Zheng; Cao, Changhong; Xu, Zongqi; Feng, Xiaohai; Xu, Hong

    2015-01-01

    Poly(L-diaminopropionic acid) (PDAP) is one of the four homopoly(amino acid)s that have been discovered in nature. However, the molecular mechanism of PDAP biosynthesis has yet to be described. In this work, the general layout of the PDAP biosynthetic pathway is characterised in Streptomyces albulus PD-1 by genome mining, gene disruption, heterologous expression and in vitro feeding experiments. As a result, L-diaminopropionic acid (L-DAP), which is the monomer of PDAP, is shown to be jointly synthesised by two protein homologues of cysteine synthetase and ornithine cyclodeaminase. Then, L-DAP is assembled into PDAP by a novel nonribosomal peptide synthetase (NRPS) with classical adenylation and peptidyl carrier protein domains. However, instead of the traditional condensation or thioesterase domain of NRPSs, this NRPS has seven transmembrane domains surrounding three tandem soluble domains at the C-terminus. As far as we know, this novel single-module NRPS structure has only been reported in poly(ε-L-lysine) synthetase. The similar NRPS structure of PDAP synthetase and poly(ε-L-lysine) synthetase may be a common characteristic of homopoly(amino acid)s synthetases. In this case, we may discover and/or design more homopoly(amino acid)s by mining this kind of novel NRPS structure in the future. PMID:26632244

  13. Rapid Trimming of Cell Surface Polysialic Acid (PolySia) by Exovesicular Sialidase Triggers Release of Preexisting Surface Neurotrophin.

    PubMed

    Sumida, Mizuki; Hane, Masaya; Yabe, Uichiro; Shimoda, Yasushi; Pearce, Oliver M T; Kiso, Makoto; Miyagi, Taeko; Sawada, Makoto; Varki, Ajit; Kitajima, Ken; Sato, Chihiro

    2015-05-22

    As acidic glycocalyx on primary mouse microglial cells and a mouse microglial cell line Ra2, expression of polysialic acid (polySia/PSA), a polymer of the sialic acid Neu5Ac (N-acetylneuraminic acid), was demonstrated. PolySia is known to modulate cell adhesion, migration, and localization of neurotrophins mainly on neural cells. PolySia on Ra2 cells disappeared very rapidly after an inflammatory stimulus. Results of knockdown and inhibitor studies indicated that rapid surface clearance of polySia was achieved by secretion of endogenous sialidase Neu1 as an exovesicular component. Neu1-mediated polySia turnover was accompanied by the release of brain-derived neurotrophic factor normally retained by polySia molecules. Introduction of a single oxygen atom change into polySia by exogenous feeding of the non-neural sialic acid Neu5Gc (N-glycolylneuraminic acid) caused resistance to Neu1-induced polySia turnover and also inhibited the associated release of brain-derived neurotrophic factor. These results indicate the importance of rapid turnover of the polySia glycocalyx by exovesicular sialidases in neurotrophin regulation.

  14. Determination of dopamine in presence of ascorbic acid and uric acid using poly (Spands Reagent) modified carbon paste electrode.

    PubMed

    Veera Manohara Reddy, Y; Prabhakara Rao, V; Vijaya Bhaskar Reddy, A; Lavanya, M; Venu, M; Lavanya, M; Madhavi, G

    2015-12-01

    In this paper, we have fabricated a modified carbon paste electrode (CPE) by electropolymerisation of spands reagent (SR) onto surface of CPE using cyclic voltammetry (CV). The developed electrode was abbreviated as poly(SR)/CPE and the surface morphology of the modified electrode was studied by using scanning electron microscopy (SEM). The developed electrode showed higher electrocatalytic properties towards the detection of dopamine (DA) in 0.1M phosphate buffer solution (PBS) at pH7.0. The effect of pH, scan rate, accumulation time and concentration of dopamine was studied at poly(SR)/CPE. The poly(SR)/CPE was successfully used as a sensor for the selective determination of DA in presence of ascorbic acid (AA) and uric acid (UA) without any interference. The poly(SR)/CPE showed a good detection limit of 0.7 μM over the linear dynamic range of 1.6 μM to 16 μM, which is extremely lower than the reported methods. The prepared poly(SR)/CPE exhibited good stability, high sensitivity, better reproducibility, low detection limit towards the determination of DA. The developed method was also applied for the determination of DA in real samples.

  15. NMR analysis and tacticity determination of poly(lactic acid) in C5D5N

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this work tacticity assignments of poly(lactic acid), (PLA), are reported for the NMR peaks from CH carbon and CH3 proton at the tetrad level in deuterated pyridine. The methyl protons are better resolved in pyridine due to solvent effects such as ring current shielding of the aromatic ring and ...

  16. The production of poly-(gamma-glutamic acid) from microorganisms and its various applications.

    PubMed

    Shih, I L; Van, Y T

    2001-09-01

    This review article deals with the chemistry and biosynthesis of poly-(gamma-glutamic acid) (gamma-PGA) produced by various strains of Bacillus. Potential applications of gamma-PGA as thickener, cryoprotectant, humectant, drug carrier, biological adhesive, flocculant, or heavy metal absorbent, etc. with biodegradability in the fields of food, cosmetics, medicine and water treatments are also reviewed.

  17. THERMAL PROPERTIES OF EXTRUDED-INJECTION MOLDED POLY (LACTIC ACID) AND MILKWEED COMPOSITES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Currently, most polymer composites utilize petroleum-based materials that are non-degradable and difficult to recycle or incur substantial cost for disposal. Green composites can be used in nondurable limited applications. In order to determine the degree of compatibility between Poly (Lactic Acid...

  18. EVALUATION OF POLY(LACTIC ACID) AND AGRICULTURAL COPRODUCTS AS GREEN COMPOSITE MATERIALS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Green composite materials of poly(lactic acid)(PLA) and agricultural coproducts such as sugar beet pulp(SBP), cuphea, lesquerella, and milkweed were compounded using a twin-screw extruder, molded by injection molding and evaluated for structural and mechanical properties using acoustic emission and ...

  19. Sugar beet pulp and poly(lactic acid) composites using methylene diphenyl diisocyanate as coupling agent

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Composites from sugar beet pulp (SBP) and poly(lactic acid) (PLA) were extruded in the presence of polymeric methylene diphenyl diisocyanate (pMDI). SBP particles were evenly distributed within the PLA matrix phase as revealed by confocal fluorescence microscopic analysis. The resultant composites w...

  20. Starch/fiber/poly(lactic acid) foam and compressed foam composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Composites of starch, fiber, and poly(lactic acid) (PLA) were made using a foam substrate formed by dehydrating starch or starch/fiber gels. PLA was infiltrated into the dry foam to provide better moisture resistance. Foam composites were compressed into plastics using force ranging from 4-76MPa. Te...

  1. Production of poly(beta-L-malic acid) (PMA) from agricultural biomass substrates by Aureobasidium pullulans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report here for the first time the production of poly(beta-L-malic acid) (PMA) from agricultural biomass substrates by the yeastlike fungus Aureobasidium pullulans. Strains NRRL Y 2311-1, NRRL 50382, NRRL 50383, and NRRL 50384, representing diverse isolation sources and phylogenetic clades, prod...

  2. Poly (beta-L-malic acid) production by diverse phylogenetic clades of Aureobasidium pullulans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly (beta-L-malic acid) (PMA) is a natural biopolyester that has pharmaceutical applications and other potential uses. Here we examine PMA production by genetically diverse phylogenetic clades of the fungus A. pullulans. Thirty-six strains of A. pullulans were isolated for this study from various...

  3. Phospholipids and poly(glutamic acid)/hydrolyzed gluten: interaction and kinetics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of poly (glutamic acid) (PGA) and Hydrolyzed wheat gluten (HG) on the thermal and kinetics properties of lysophosphatidylcholine (LPC) was determined using Differential Scanning Calorimetry (DSC). A model system containing 3, 6 and 10% PGA or HG was added to 40% LPC aqueous suspension. ...

  4. Poly(beta-L-malic acid) from agricultural substrates by Aureobasidium pullulans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report here for the first time the production of poly(beta-L-malic acid) (PMA) from agricultural substrates by the yeastlike fungus Aureobasidium pullulans. PMA is a natural biopolyester that has primarily been studied for biomedical uses as a drug carrier. However, PMA also has potential as a ...

  5. Poly(lactic acid) and Osage Orange Wood Fiber Composites for Agricultural Mulch Films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Osage orange wood(OO)was combined with poly(lactic acid)(PLA)to form a polymer composite intended for use as an agricultural mulch film. The PLA-OO mechanical properties were comparable to existing mulch film products and had the advantage of being completely biodegradable through a single growing ...

  6. Poly(lactic acid) and Osage Orange Wood Fiber Composites for Agricultural Mulch Films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Osage orange wood was combined with poly(lactic acid) to form a polymer composite intendedfor use as an agricultural mulch film. The mechanical properties were comparable to existing products and had the advantage of being completely biodegradable through a single growing season. PLA-OO composites...

  7. Evaluation of cotton byproducts as fillers for poly(lactic acid) and low density polyethylene

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polymeric composites based on cotton burr and cottonseed bull have been prepared by melt blending and extrusion. For poly(lactic acid) (PLA) and low-density polyethylene (LDPE), addition of the fillers only slightly changed the composite’s thermal properties and significantly decreased the composite...

  8. Enthalpy changes upon dilution and ionization of poly(L-glutamic acid) in aqueous solutions.

    PubMed

    Godec, Andrej; Skerjanc, Joze

    2005-07-14

    The enthalpy changes accompanying the dilution and ionization of poly(L-glutamic acid) in water have been measured at 25 degrees C for two degrees of polymerization (DP = 115 and DP = 480) at various degrees of ionization, alpha, for a concentration range from about 0.2 to 0.002 monomol/L. The heat of dilution displays an unusual dependence on the degree of ionization, which is in sharp contrast to the behavior of other weak carboxylic polyelectrolytes, such as poly(acrylic acid). The exothermic heat effects observed at low values of alpha become endothermic for the region where the helix-coil transition is most pronounced, and for high degrees of ionization, they are exothermic again. Evidently, an endothermic heat effect, produced by an additional conformational transition in the dilution process, is superimposed on the exothermic enthalpy of dilution, and it overweighs the latter in the region of alpha where the conformational transition is prevailing. The calorimetric titration curve, which gives the dependence of the heat of ionization, deltaH(i), on alpha, has a maximum and is typical for poly(carboxylic acids) which undergo pH-induced conformational transition, such as poly(methacrylic acid). The values of deltaH(i) obtained at two polymer concentrations indicate that the enthalpy of ionization depends on the polypeptide concentration.

  9. Solution blow spun Poly(lactic acid)/Hydroxypropyl methylcellulose nanofibers with antimicrobial properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly(lactic acid) (PLA) nanofibers containing hydroxypropyl methylcellulose (HPMC) and tetracycline hydrochloride (THC) were solution blow spun from two different solvents, chloroform/acetone (CA, 80:20 v/v) and 2,2,2-triflouroethanol (TFE). The diameter distribution, chemical, thermal, thermal stab...

  10. Low-Melt Poly(Amic Acids) and Polyimides and Their Uses

    NASA Technical Reports Server (NTRS)

    Jolley, Scott T. (Inventor); Gibson, Tracy L. (Inventor); Williams, Martha K. (Inventor); Parrish, Clyde F. (Inventor); Snyder, Sarah J. (Inventor)

    2016-01-01

    Provided are low-melt polyimides and poly(amic acids) (PAAs) for use as adhesives, and methods of using the materials for attaching two substrates. The methods typically form an adhesive bond that is hermetically sealed to both substrates. Additionally, the method typically forms a cross-linked bonding material that is flexible.

  11. Low-Melt Poly(amic Acids) and Polyimides and Their Uses

    NASA Technical Reports Server (NTRS)

    Jolley, Scott T. (Inventor); Gibson, Tracy L. (Inventor); Williams, Martha K. (Inventor); Parrish, Clyde F. (Inventor); Parks, Steven L. (Inventor)

    2015-01-01

    Provided are low-melt polyimides and poly(amic acids) (PAAs) for use in repair of electrical wire insulation, flat or ribbon wire harnesses, and flat surfaces comprised of high-performance polymers such as inflatables or solar panels applications. Also provided are methods and devices for repair of electrical insulation.

  12. Low-Melt Poly(Amic Acids) and Polyimides and Their Uses

    NASA Technical Reports Server (NTRS)

    Jolley, Scott T. (Inventor); Gibson, Tracy L. (Inventor); Williams, Martha K. (Inventor); Parrish, Clyde F. (Inventor); Parks, Steven L. (Inventor)

    2014-01-01

    Provided are low-melt polyimides and poly(amic acids) (PAAs) for use in repair of electrical wire insulation, flat or ribbon wire harnesses, and flat surfaces comprised of high-performance polymers such as inflatables or solar panels applications. Also provided are methods and devices for repair of electrical insulation.

  13. Cationic poly(lactic-co-glycolic acid) iron oxide microspheres for nucleic acid detection

    NASA Astrophysics Data System (ADS)

    Pandey, Chandra Mouli; Sharma, Aditya; Sumana, Gajjala; Tiwari, Ida; Malhotra, Bansi Dhar

    2013-04-01

    Herein, we envisage the possibility of preparing stable cationic poly(lactic-co-glycolic acid) (PLGA) microspheres encapsulating the iron oxide nanoparticles (IONPs; 8-12 nm). The IONPs are incorporated into PLGA in organic phase followed by microsphere formation and chitosan coating in aqueous medium via nano-emulsion technique. The average size of the microspheres, as determined by dynamic light scattering are about 310 nm, while the zeta potential for the composite remains near 35 mV at pH 4.0. These microspheres are electrophoretically deposited onto indium tin oxide (ITO)-coated glass substrate used as cathode and parallel platinum plate as the counter electrode. This platform is utilized to fabricate a DNA biosensor, by immobilizing a probe sequence specific to Escherichia coli. The bioelectrode shows a surface-controlled electrode reaction with the electron transfer coefficient (α) of 0.64 and charge transfer rate constant (ks) of 61.73 s-1. Under the optimal conditions, this biosensor shows a detection limit of 8.7 × 10-14 M and is found to retain about 81% of the initial activity after 9 cycles of use.Herein, we envisage the possibility of preparing stable cationic poly(lactic-co-glycolic acid) (PLGA) microspheres encapsulating the iron oxide nanoparticles (IONPs; 8-12 nm). The IONPs are incorporated into PLGA in organic phase followed by microsphere formation and chitosan coating in aqueous medium via nano-emulsion technique. The average size of the microspheres, as determined by dynamic light scattering are about 310 nm, while the zeta potential for the composite remains near 35 mV at pH 4.0. These microspheres are electrophoretically deposited onto indium tin oxide (ITO)-coated glass substrate used as cathode and parallel platinum plate as the counter electrode. This platform is utilized to fabricate a DNA biosensor, by immobilizing a probe sequence specific to Escherichia coli. The bioelectrode shows a surface-controlled electrode reaction with the

  14. Reinforced Poly(Propylene Carbonate) Composite with Enhanced and Tunable Characteristics, an Alternative for Poly(lactic Acid).

    PubMed

    Manavitehrani, Iman; Fathi, Ali; Wang, Yiwei; Maitz, Peter K; Dehghani, Fariba

    2015-10-14

    The acidic nature of the degradation products of polyesters often leads to unpredictable clinical complications, such as necrosis of host tissues and massive immune cell invasions. In this study, poly(propylene carbonate) (PPC) and starch composite is introduced with superior characteristics as an alternative to polyester-based polymers. The degradation products of PPC-starch composites are mainly carbon dioxide and water; hence, the associated risks to the acidic degradation of polyesters are minimized. Moreover, the compression strength of PPC-starch composites can be tuned over the range of 0.2±0.03 MPa to 33.9±1.51 MPa by changing the starch contents of composites to address different clinical needs. More importantly, the addition of 50 wt % starch enhances the thermal processing capacity of the composites by elevating their decomposition temperature from 245 to 276 °C. Therefore, thermal processing methods, such as extrusion and hot melt compression methods can be used to generate different shapes and structures from PPC-starch composites. We also demonstrated the cytocompatibility and biocompatibility of these composites by conducting in vitro and in vivo tests. For instance, the numbers of osteoblast cells were increased 2.5 fold after 7 days post culture. In addition, PPC composites in subcutaneous mice model resulted in mild inflammatory responses (e.g., the formation of fibrotic tissue) that were diminished from two to 4 weeks postimplantation. The long-term in vivo biodegradation of PPC composites are compared with poly(lactic acid) (PLA). The histochemical analysis revealed that after 8 weeks, the biodegradation of PLA leads to massive immune cell infusion and inflammation at the site, whereas the PPC composites are well-tolerated in vivo. All these results underline the favorable properties of PPC-starch composites as a benign biodegradable biomaterial for fabrication of biomedical implants.

  15. Synthesis and physicochemical properties of two analogs of poly(dA): poly(2-aminopurine-9-beta-D-deoxyribonucleotide) and poly 2-amino-deoxyadenylic acid.

    PubMed Central

    Scheit, K H; Rackwitz, H R

    1982-01-01

    Polymerization of chemically synthesized dn2h6ATP and dn2ATP by deoxynucleotidyl transferase from calf thymus furnished poly(dn2h6A) and poly(dn2A) respectively. The synthetic polynucleotides were characterized by spectroscopic, ultracentrifugation and enzymatic methods. In polynucleotide-polynucleotide interaction, poly(dn2h6A) and poly(dn2A) behaved like analogs of poly(dnA). PMID:6287431

  16. Controlling E. coli adhesion on high-k dielectric bioceramics films using poly(amino acid) multilayers.

    PubMed

    Lawrence, Neil J; Wells-Kingsbury, Jamie M; Ihrig, Marcella M; Fangman, Teresa E; Namavar, Fereydoon; Cheung, Chin Li

    2012-03-06

    The influence of high-k dielectric bioceramics with poly(amino acid) multilayer coatings on the adhesion behavior of Escherichia coli (E. coli) was studied by evaluating the density of bacteria coverage on the surfaces of these materials. A biofilm forming K-12 strain (PHL628), a wild-type strain (JM109), and an engineered strain (XL1-Blue) of E. coli were examined for their adherence to zirconium oxide (ZrO(2)) and tantalum oxide (Ta(2)O(5)) surfaces functionalized with single and multiple layers of poly(amino acid) polyelectrolytes made by the layer-by-layer (LBL) deposition. Two poly(amino acids), poly(l-arginine) (PARG) and poly(l-aspartic acid) (PASP), were chosen for the functionalization schemes. All three strains were found to grow and preferentially adhere to bare bioceramic film surfaces over bare glass slides. The bioceramic and glass surfaces functionalized with positively charged poly(amino acid) top layers were observed to enhance the adhesion of these bacteria by up to 4-fold in terms of bacteria surface coverage. Minimal bacteria coverage was detected on surfaces functionalized with negatively charged poly(amino acid) top layers. The effect of different poly(amino acid) coatings to promote or minimize bacterial adhesion was observed to be drastically enhanced with the bioceramic substrates than with glass. Such observed enhancements were postulated to be attributed to the formation of higher density of poly(amino acids) coatings enabled by the high dielectric strength (k) of these bioceramics. The multilayer poly(amino acid) functionalization scheme was successfully applied to utilize this finding for micropatterning E. coli on bioceramic thin films.

  17. Hydrophilic poly (ethylene glycol) capped poly (lactic-co-glycolic) acid nanoparticles for subcutaneous delivery of insulin in diabetic rats.

    PubMed

    S, Saravanan; S, Malathi; P S L, Sesh; S, Selvasubramanian; S, Balasubramanian; V, Pandiyan

    2017-02-01

    The aim of the present study is to evaluate the effect of insulin loaded poly(ethylene glycol) capped poly(lactic-co-glycolic)acid nanoparticles (ISPPLG NPs) by subcutaneous administration in diabetic rats. A series of biodegradable low molecular weight PLGA [90/10 (PLG2) and 80/20 (PLG4)] copolymers were synthesized by melt polycondensation and their ISPPLG NPs were synthesized by water-oil-water (W/O/W) emulsion solvent evaporation method. The PLGA copolymers and their nanoparticles were characterized. The maximum encapsulation efficiency of ISPPLG4 NPs is 66% and the diameter of the nanoparticles is about 140nm. The in-vivo studies of ISPPLG NPs carried out in diabetic rats by subcutaneous administration show considerable reduction in serum glucose level along with partial restoration of tissue defense systems. Histopathological studies reveal that ISPPLG NPs could restore the damages caused by oxidants during hyperglycaemia. The subcutaneous administration of ISPPLG4 NPs is thus an effective method of reducing hyperglycaemia associated complications.

  18. Biodegradability and mechanical properties of poly(butylene succinate) composites with finely dispersed hydrophilic poly(acrylic acid)

    NASA Astrophysics Data System (ADS)

    Mizuno, Sawako; Hotta, Atsushi

    2014-03-01

    Biodegradability and mechanical properties of aliphatic poly(butylene succinate) (PBS) films with finely dispersed hydrophilic poly(acrylic acid) (PAA) were investigated. First, 3.5 wt% of PAA was chemically grafted onto the surface of the PBS films (surface-grafted PBS) by photo grafting polymerization, and then the grafted PAA was homogeneously and finely dispersed into PBS by dissolving the surface-grafted PBS into chloroform before mixing and drying to get solid PAA-dispersed PBS. Degradation of these modified PBS was investigated using gel permeation chromatography (GPC) and tensile testing. According to the GPC results, it was found that the PAA-dispersed PBS had intermediate biodegradability with the intermediate water intake, and the reaction constant of PAA-dispersed PBS was in between those of untreated PBS and surface-grafted PBS, in fact 25% higher and 17% lower, respectively. The experimental results presented that the biodegradability of PBS could be well controlled by the dispersion of PAA, possibly leading to the widespread use of PBS for biodegradable polymers.

  19. Biocompatibility of poly(ethylene glycol) and poly(acrylic acid) interpenetrating network hydrogel by intrastromal implantation in rabbit cornea

    PubMed Central

    Zheng, Luo Luo; Vanchinathan, Vijay; Dalal, Roopa; Noolandi, Jaan; Waters, Dale J.; Hartmann, Laura; Cochran, Jennifer R.; Frank, Curtis W.; Yu, Charles Q.; Ta, Christopher N.

    2015-01-01

    We evaluated the biocompatibility of a poly(ethylene glycol) and poly(acrylic acid) (PEG/PAA) interpenetrating network hydrogel designed for artificial cornea in a rabbit model. PEG/PAA hydrogel measuring 6 mm in diameter was implanted in the corneal stroma of twelve rabbits. Stromal flaps were created with a microkeratome. Randomly, six rabbits were assigned to bear the implant for 2 months, two rabbits for 6 months, two rabbits for 9 months, one rabbit for 12 months, and one rabbit for 16 months. Rabbits were evaluated monthly. After the assigned period, eyes were enucleated, and corneas were processed for histology and immunohistochemistry. There were clear corneas in three of six rabbits that had implantation of hydrogel for 2 months. In the six rabbits with implant for 6 months or longer, the corneas remained clear in four. There was a high rate of epithelial defect and corneal thinning in these six rabbits. One planned 9-month rabbit developed extrusion of implant at 4 months. The cornea remained clear in the 16-month rabbit but histology revealed epithelial in-growth. Intrastromal implantation of PEG/PAA resulted in a high rate of long-term complications. PMID:25778285

  20. Controllable drug release of electrospun thermoresponsive poly(N-isopropylacrylamide)/poly(2-acrylamido-2- methylpropanesulfonic acid) nanofibers.

    PubMed

    Lin, Xiuling; Tang, Dongyan; Cui, Weiwei; Cheng, Yan

    2012-07-01

    Electrospinning micro- and nanofibers are being increasingly investigated for drug delivery. The components and their stimuli-responsive properties of fibers are important factors influencing the drug release behavior. The aim of this study is to fabricate thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm)/poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) nanofibers by single-spinneret electrospinning technique. The electrospun nanofibers are used as a drug carrier by cospinning with nifedipine (NIF), and the release behaviors of NIF from the thermoresponsive nanofibers can be controlled by the response of nanofibers with temperature. The morphology of the nanofibers and its composites with NIF was determined by scanning electron microscopy (SEM). The hydrogen bond interactions between PNIPAAm/PAMPS and the water-insoluble drug of NIF were introduced and confirmed by Fourier-transform infrared spectroscopy and energy dispersive spectrometer. The thermoresponsive properties of nanofibers were investigated by contact angle (CA) measurements. The release behaviors of NIF from the PNIPAAm/PAMPS nanofibers were observed by SEM and demonstrated by UV-vis spectroscopy. It was found that uniform fibers of NIF and PNIPAAm/PAMPS could be fabricated without particles on the surface. The release of NIF from nanofibers could be controlled effectively by the changes of hydrogen bonds between PNIPAAm/PAMPS and NIF, and by adjusting temperatures of the thermoresponsive nanofibers.

  1. Bioceramic/poly (glycolic)-poly (lactic acid) composite induces mineralized barrier after direct capping of rat tooth pulp tissue.

    PubMed

    Gala-Garcia, Alfonso; Teixeira, Karina Imaculada Rosa; Wykrota, Francisco Henrique Lana; Sinisterra, Rubén Dario; Cortés, Maria Esperanza

    2010-01-01

    The aim of this study was to observe the histopathological pulp response following direct pulp capping of mechanically exposed teeth in rats with a composite of beta-tricalcium phosphate-hydroxyapatite bioceramic (BC) and poly (glycolic)-poly (lactic acid) (PLGA) material or a calcium hydroxide [Ca(OH)2] material, compared to BC alone and a negative control of water. Pulp of the maxillary molars was exposed, followed by capping with the experimental material. The pulpal tissue response was assessed post-operatively at 1, 7, 14 and 30 d, followed by histological analysis. The Ca(OH)2 group exhibited severe acute inflammatory cell infiltration at day 14. However after 30 d, a new hard tissue with macro porous obliteration of the pulp chamber and a characteristic necrotic area had appeared. BC and Ca(OH)2 capping were associated with moderate inflammation and dentinal bridge similar. Meanwhile, in the BC/PLGA composite group, there was moderate inflammatory infiltrate and formation of a dense and complete dentinal bridge. In conclusion, the BC/PLGA composite material showed a large zone of tertiary dentin, and effectively reorganized the dentin-pulp complex.

  2. Structural characterization of a poly(methacrylic acid)-poly(methyl methacrylate) copolymer by nuclear magnetic resonance and mass spectrometry.

    PubMed

    Giordanengo, Rémi; Viel, Stéphane; Hidalgo, Manuel; Allard-Breton, Béatrice; Thévand, André; Charles, Laurence

    2009-11-03

    Mass spectrometry (MS) and nuclear magnetic resonance (NMR) have been combined to achieve the complete microstructural characterization of a poly(methacrylic acid)-poly(methyl methacrylate) (PMAA-PMMA) copolymer synthesized by nitroxide-mediated polymerization. Various PMAA-PMMA species could be identified which mainly differ in terms of terminaisons. 1H and 13C NMR experiments revealed the structure of the end-groups as well as the proportion of each co-monomer in the copolymers. These end-group masses were further confirmed from m/z values of doubly charged copolymer anions detected in the single stage mass spectrum. In contrast, copolymer composition derived from MS data was not consistent with NMR results, obviously due to strong mass bias well known to occur during electrospray ionization of these polymeric species. Tandem mass spectrometry could reveal the random nature of the copolymer based on typical dissociation reactions, i.e., water elimination occurred from any two contiguous MAA units while MAA-MMA pairs gave rise to the loss of a methanol molecule. Polymer backbone cleavages were also observed to occur and gave low abundance fragment ions which allowed the structure of the initiating end-group to be confirmed.

  3. Poly(ethylene glycol)-poly(lactic-co-glycolic acid) based thermosensitive injectable hydrogels for biomedical applications.

    PubMed

    Alexander, Amit; Ajazuddin; Khan, Junaid; Saraf, Swarnlata; Saraf, Shailendra

    2013-12-28

    Stimuli triggered polymers provide a variety of applications related with the biomedical fields. Among various stimuli triggered mechanisms, thermoresponsive mechanisms have been extensively investigated, as they are relatively more convenient and effective stimuli for biomedical applications. In a contemporary approach for achieving the sustained action of proteins, peptides and bioactives, injectable depots and implants have always remained the thrust areas of research. In the same series, Poloxamer based thermogelling copolymers have their own limitations regarding biodegradability. Thus, there is a need to have an alternative biomaterial for the formulation of injectable hydrogel, which must remain biocompatible along with safety and efficacy. In the same context, poly(ethylene glycol) (PEG) based copolymers play a crucial role as a biomedical material for biomedical applications, because of their biocompatibility, biodegradability, thermosensitivity and easy controlled characters. This review stresses on the physicochemical property, stability and composition prospects of smart PEG/poly(lactic-co-glycolic acid) (PLGA) based thermoresponsive injectable hydrogels, recently utilized for biomedical applications. The manuscript also highlights the synthesis scheme and stability characteristics of these copolymers, which will surely help the researchers working in the same area. We have also emphasized the applied use of these smart copolymers along with their formulation problems, which could help in understanding the possible modifications related with these, to overcome their inherent associated limitations.

  4. Biocompatibility of poly(ethylene glycol) and poly(acrylic acid) interpenetrating network hydrogel by intrastromal implantation in rabbit cornea.

    PubMed

    Zheng, Luo Luo; Vanchinathan, Vijay; Dalal, Roopa; Noolandi, Jaan; Waters, Dale J; Hartmann, Laura; Cochran, Jennifer R; Frank, Curtis W; Yu, Charles Q; Ta, Christopher N

    2015-10-01

    We evaluated the biocompatibility of a poly(ethylene glycol) and poly(acrylic acid) (PEG/PAA) interpenetrating network hydrogel designed for artificial cornea in a rabbit model. PEG/PAA hydrogel measuring 6 mm in diameter was implanted in the corneal stroma of twelve rabbits. Stromal flaps were created with a microkeratome. Randomly, six rabbits were assigned to bear the implant for 2 months, two rabbits for 6 months, two rabbits for 9 months, one rabbit for 12 months, and one rabbit for 16 months. Rabbits were evaluated monthly. After the assigned period, eyes were enucleated, and corneas were processed for histology and immunohistochemistry. There were clear corneas in three of six rabbits that had implantation of hydrogel for 2 months. In the six rabbits with implant for 6 months or longer, the corneas remained clear in four. There was a high rate of epithelial defect and corneal thinning in these six rabbits. One planned 9-month rabbit developed extrusion of implant at 4 months. The cornea remained clear in the 16-month rabbit but histology revealed epithelial in-growth. Intrastromal implantation of PEG/PAA resulted in a high rate of long-term complications.

  5. Physical characterization of thin semi-porous poly(L-lactic acid)/poly(ethylene glycol) membranes for tissue engineering.

    PubMed

    Swaminathan, V; Tchao, R; Jonnalagadda, S

    2007-01-01

    This study examines physical properties of solvent-cast poly(L-lactic acid) (PLLA): poly(ethylene glycol) PEG membranes as a function of PEG molecular weight (MW) and incubation in vitro for 6 weeks. PEGs of MW 400, 1450 and 8000 were used. The morphological, thermal, mechanical and permeability properties of the membranes were studied prior to and after 3 and 6 weeks of incubation in phosphate-buffered saline (PBS) at 37 degrees C. The membranes showed a thickness of about 35+/-5 microm and were found to be semi-porous, with a non-porous surface as well as a porous surface with pore-diameters of 0.5-5 microm. The surface pore size was found to be a function of PEG MW used. All membranes were mechanically strong, with elastic moduli and tensile strength of 150-440 MPa and 7-36 MPa, respectively, all through the 6-week incubation period. The lower-MW PEGs plasticized PLLA based on high initial percent elongation; however, the effect was lost after 3 weeks of incubation in PBS. All membranes except those fabricated with PEG 8000 were impermeable for up to 6 weeks of incubation in PBS. Permeability studies showed that only PLLA:PEG 8000 membranes were permeable to methylene blue after 3 weeks of degradation.

  6. In-vitro degradation characteristics of poly(e-caprolactone)/poly(glycolic acid) scaffolds fabricated via solid-state cryomilling.

    PubMed

    Jonnalagadda, John B; Rivero, Iris V; Warzywoda, Juliusz

    2015-10-01

    Poly(e-caprolactone) (PCL)/poly(glycolic acid) (PGA) scaffolds were fabricated via solid-state cryomilling along with compression molding and porogen leaching techniques. Four types of scaffolds were produced using four distinct cryomilling times. These scaffolds were evaluated for their in-vitro degradation behavior hydrolytically in phosphate buffer saline (PBS). The degradation profiles were investigated over a period of 60 days. The percentage of weight loss, percentage of water absorption, morphology, compressive, thermal, and material properties were studied as a function of degradation time. Weight loss and water absorption demonstrated a high correlation, which showed an increasing behavior with increase in cryomilling time and degradation time. Morphology of the scaffolds analyzed through scanning electron microscopy (SEM) revealed micro-cracks on the surface of the cylindrical struts due to hydrolytic attack and dissolution of hydrophilic PGA. Changes in compressive modulus and crystallinity over the degradation period and material properties were analyzed using X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. DSC and XRD results indicated that hydrolytic attack had taken place during degradation, resulting in moments of increased and decreased percent crystallinity. This study successfully brought forth the differences in resultant properties of the PCL/PGA scaffolds as a function of degradation time.

  7. Effect of diameter of poly(lactic acid) fiber on the physical properties of poly(ɛ-caprolactone).

    PubMed

    Ju, Dandan; Han, Lijing; Guo, Ziqi; Bian, Junjia; Li, Fan; Chen, Shan; Dong, Lisong

    2015-05-01

    Biodegradable polymer composites based on poly(ɛ-caprolactone) (PCL) and poly(lactic acid) (PLA) fibers with diameters of 18, 26, 180 μm were prepared by melt compounding. The PLA fiber content in the composites was constant at 20% by weight. The effects of fibers with different diameters on the physical properties and enzymatic degradation of PCL were investigated. The morphological analysis indicated good interfacial adhesion between PCL and PLA fiber, which was beneficial to improve the physical properties of PCL. With increasing PLA fiber diameter, the complex viscosity and modulus of PCL were significantly increased, especially at low frequencies, indicating that the hindered effect of the fiber on the mobility of the PCL molecular chains was more obvious when PLA fiber diameter was thicker. However, as for the mechanical properties, the reinforcement was more obvious to PCL with the smaller PLA fiber diameter. This was because increasing efficient load transfer may be appeared due to the larger surface area and better interface bonding force of the fiber with thinner diameters. The enzymatic degradation of PCL was accelerated with the addition of large PLA fiber diameter of 26 and 180 μm, and hardly changed with the small PLA fiber diameter of 18 μm.

  8. Preparation, melting behavior and thermal stability of poly(lactic acid)/poly(propylene carbonate) blends processed by vane extruder

    NASA Astrophysics Data System (ADS)

    Zou, Wei; Chen, Rongyuan; Zhang, Haichen; Qu, Jinping

    2016-03-01

    Poly (lactic acid) (PLA)/Poly (propylene carbonate) (PPC) blends were prepared by vane extruder which is a type of novel polymer processing extruder based on elongation force field. Scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetric (TG) were used respectively to analyze the compatibility, the melting behavior and thermal stability properties of PLA/PPC blends affected by the different content of PPC. The results showed that with the increase of the PPC content, the glass transition temperature of PLA was reduced, and the glass transition temperature of PPC was increased, which indicated that PLA and PPC had partial compatibility. The cold crystallization temperature of PLA increased with the increase of the PPC content, which showed that PPC hindered the cold crystallization process of PLA. The addition of PPC had little impact on the melting process of PLA, and the melting temperature of PLA was almost kept the same value. Thermogravimetric analysis showed that the thermal stability of PPC was worse than that of PLA, the addition of PPC reduced the thermal stability of PLA.

  9. Poly(acrylic acid)-grafted poly(N-isopropyl acrylamide) networks: preparation, characterization and hydrogel behavior.

    PubMed

    Yu, Rentong; Zheng, Sixun

    2011-01-01

    Poly(acrylic acid)-grafted poly(N-isopropylacrylamide) co-polymer networks (PNIPAAm-g-PAA) were prepared via the reversible addition-fragmentation transfer (RAFT) polymerization of N-isopropyl- acrylamide (NIPAAm) with trithiocarbonate-terminated PAA as a macromolecular chain-transfer agent in the presence of N,N-methylenebisacrylamide. The PNIPAAm-g-PAA co-polymer networks were characterized by means of Fourier transform infrared spectroscopy, differential scanning calorimetry and small-angle X-ray scattering. It is found that the PNIPAAm-g-PAA co-polymer networks were microphase-separated, in which the microdomains of PNIPAAm-PAA interpolymer complexes were dispersed into the PNIPAAm matrix. The PNIPAAm-g-PAA hydrogels displayed a dual response to temperature and pH values. The thermoresponsive properties of PNIPAAm-g-PAA networks were investigated. Below the volume phase transition temperatures, the PNIPAAm-g-PAA hydrogels possessed much higher swelling ratios than control PNIPAAm hydrogel. In terms of swelling, deswelling and reswelling tests, it is judged that the PNIPAAm-g-PAA hydrogels displayed faster response to the external temperature changes than control PNIPAAm hydrogel. The improved thermoresponsive properties of hydrogels are ascribed to the formation of PAA-grafted PNIPAAm networks, in which the water-soluble PAA chains behave as the hydrophiphilic tunnels and allow water molecules to go through and, thus, to accelerate the diffusion of water molecules.

  10. Electrospun Poly(L-Lactic Acid)-co-Poly(ϵ-Caprolactone) Nanofibres Containing Silver Nanoparticles for Skin-Tissue Engineering.

    PubMed

    Jin, Guorui; Prabhakaran, Molamma P; Nadappuram, Binoy P; Singh, Gurdev; Kai, Dan; Ramakrishna, Seeram

    2012-01-01

    Silver nanoparticles (AgNPs) and silver ions (Ag(+)) show growth-inhibitory activity against microorganisms and have been used for decades as antibacterial agents in various fields. To fabricate a nanofibrous scaffold which is antibacterial against bacteria and non-toxic to cells, we electrospun composite poly(L-lactic acid)-co-poly(ϵ-caprolactone) nanofibres containing silver nanoparticles (PLLCL-AgNPs) with different concentrations (0.25, 0.50 and 0.75 wt%) of silver nitrate (AgNO3) in PLLCL. The diameters of the electrospun PLLCL-AgNPs nanofibres decreased with the increase of AgNO3 concentration in PLLCL solutions. Human skin fibroblasts cultured on the scaffolds showed that the PLLCL nanofibres containing lesser amounts of AgNPs (0.25 wt%) had better cell proliferation and retained the cell morphology similar to the phenotype observed on tissue culture plates (control). The antibacterial activity of AgNPs in PLLCL nanofibres was investigated against Staphylococcus aureus and Salmonella enterica and the antimicrobial activity was found to increase with the increasing concentration of nanoparticles present in the scaffold. Based on our studies, we propose that PLLCL nanofibres containing 0.25 wt% AgNO3 or PLLCL-Ag(25), favors cell proliferation and inhibits bacteria and could be a suitable substrate for wound healing.

  11. Directed self-assembly of poly(styrene)-block-poly(acrylic acid) copolymers for sub-20nm pitch patterning

    NASA Astrophysics Data System (ADS)

    Cheng, Jing; Lawson, Richard A.; Yeh, Wei-Ming; Jarnagin, Nathan D.; Peters, Andrew; Tolbert, Laren M.; Henderson, Clifford L.

    2012-03-01

    Directed self-assembly (DSA) of block copolymers is a promising technology for extending the patterning capability of current lithographic exposure tools. For example, production of sub-40 nm pitch features using 193nm exposure technologies is conceivably possible using DSA methods without relying on time consuming, challenging, and expensive multiple patterning schemes. Significant recent work has focused on demonstration of the ability to produce large areas of regular grating structures with low numbers of defects using self-assembly of poly(styrene)-b-poly(methyl methacrylate) copolymers (PS-b-PMMA). While these recent results are promising and have shown the ability to print pitches approaching 20 nm using DSA, the ability to advance to even smaller pitches will be dependent upon the ability to develop new block copolymers with higher χ values and the associated alignment and block removal processes required to achieve successful DSA with these new materials. This paper reports on work focused on identifying higher χ block copolymers and their associated DSA processes for sub-20 nm pitch patterning. In this work, DSA using polystyrene-b-polyacid materials has been explored. Specifically, it is shown that poly(styrene)-b-poly(acrylic acid) copolymers (PS-b-PAA) is one promising material for achieving substantially smaller pitch patterns than those possible with PS-b-PMMA while still utilizing simple hydrocarbon polymers. In fact, it is anticipated that much of the learning that has been done with the PS-b-PMMA system, such as development of highly selective plasma etch block removal procedures, can be directly leveraged or transferred to the PS-b-PAA system. Acetone vapor annealing of PS-b-PAA (Mw=16,000 g/mol with 50:50 mole ratio of PS:PAA) and its self-assembly into a lamellar morphology is demonstrated to generate a pattern pitch size (L0) of 21 nm. The χ value for PS-b-PAA was estimated from fingerprint pattern pitch data to be approximately 0.18 which

  12. Self-Healing Supramolecular Self-Assembled Hydrogels Based on Poly(L-glutamic acid).

    PubMed

    Li, Guifei; Wu, Jie; Wang, Bo; Yan, Shifeng; Zhang, Kunxi; Ding, Jianxun; Yin, Jingbo

    2015-11-09

    Self-healing polymeric hydrogels have the capability to recover their structures and functionalities upon injury, which are extremely attractive in emerging biomedical applications. This research reports a new kind of self-healing polypeptide hydrogels based on self-assembly between cholesterol (Chol)-modified triblock poly(L-glutamic acid)-block-poly(ethylene glycol)-block-poly(L-glutamic acid) ((PLGA-b-PEG-b-PLGA)-g-Chol) and β-cyclodextrin (β-CD)-modified poly(L-glutamic acid) (PLGA-g-β-CD). The hydrogel formation relied on the host and guest linkage between β-CD and Chol. This study demonstrates the influences of polymer concentration and β-CD/Chol molar ratio on viscoelastic behavior of the hydrogels. The results showed that storage modulus was highest at polymer concentration of 15% w/v and β-CD/Chol molar ratio of 1:1. The effect of the PLGA molecular weight in (PLGA-b-PEG-b-PLGA)-g-Chol on viscoelastic behavior, mechanical properties and in vitro degradation of the supramolecular hydrogels was also studied. The hydrogels showed outstanding self-healing capability and good cytocompatibility. The multilayer structure was constructed using hydrogels with self-healing ability. The developed hydrogels provide a fascinating glimpse for the applications in tissue engineering.

  13. Identification of a novel malonyl-CoA IC(50) for CPT-I: implications for predicting in vivo fatty acid oxidation rates.

    PubMed

    Smith, Brennan K; Perry, Christopher G R; Koves, Timothy R; Wright, David C; Smith, Jeffrey C; Neufer, P Darrell; Muoio, Deborah M; Holloway, Graham P

    2012-11-15

    Published values regarding the sensitivity (IC(50)) of CPT-I (carnitine palmitoyltransferase I) to M-CoA (malonyl-CoA) inhibition in isolated mitochondria are inconsistent with predicted in vivo rates of fatty acid oxidation. Therefore we have re-examined M-CoA inhibition kinetics under various P-CoA (palmitoyl-CoA) concentrations in both isolated mitochondria and PMFs (permeabilized muscle fibres). PMFs have an 18-fold higher IC(50) (0.61 compared with 0.034 μM) in the presence of 25 μM P-CoA and a 13-fold higher IC(50) (6.3 compared with 0.49 μM) in the presence of 150 μM P-CoA compared with isolated mitochondria. M-CoA inhibition kinetics determined in PMFs predicts that CPT-I activity is inhibited by 33% in resting muscle compared with >95% in isolated mitochondria. Additionally, the ability of M-CoA to inhibit CPT-I appears to be dependent on P-CoA concentration, as the relative inhibitory capacity of M-CoA is decreased with increasing P-CoA concentrations. Altogether, the use of PMFs appears to provide an M-CoA IC(50) that better reflects the predicted in vivo rates of fatty acid oxidation. These findings also demonstrate that the ratio of [P-CoA]/[M-CoA] is critical for regulating CPT-I activity and may partially rectify the in vivo disconnect between M-CoA content and CPT-I flux within the context of exercise and Type 2 diabetes.

  14. Identification of a novel malonyl-CoA IC50 for CPT-1: implications for predicting in vivo fatty acid oxidation rates

    PubMed Central

    Smith, Brennan K.; Perry, Christopher G.R.; Koves, Timothy R.; Wright, David C.; Smith, Jeffrey C.; Neufer, P. Darrell; Muoio, Deborah M.; Holloway, Graham P.

    2013-01-01

    Synopsis Published values regarding the sensitivity (IC50) of carnitine palmitoyl transferase I (CPT-I) to malonyl-CoA (M-CoA) inhibition in isolated mitochondria are inconsistent with predicted in vivo rates of fatty acid oxidation. Therefore, we have re-examined M-CoA inhibition kinetics under varying palmitoyl-CoA (P-CoA) concentrations in both isolated mitochondria and permeabilized muscle fibres (PMF). PMF have an 18-fold higher IC50 (0.61 vs 0.034 μM) in the presence of 25 μM P-CoA and a 13-fold higher IC50 (6.3 vs 0.49 μM) in the presence of 150 μM P-CoA compared to isolated mitochondria. M-CoA inhibition kinetics determined in PMF predicts that CPT-I activity is inhibited by 33% in resting muscle compared to >95% in isolated mitochondria. Additionally, the ability of M-CoA to inhibit CPT-I appears to be dependent on P-CoA concentration, as the relative inhibitory capacity of M-CoA is decreased with increasing P-CoA concentrations. Altogether, the use of PMF appears to provide a M-CoA IC50 that better reflects the predicted in vivo rates of fatty acid oxidation. These findings also demonstrate the ratio of [P-CoA]/[M-CoA] is critical for regulating CPT-I activity and may partially rectify the in vivo disconnect between M-CoA content and CPT-I flux within the context of exercise and type II diabetes. PMID:22928974

  15. Poly(acrylic acid)-block-poly(vinyl alcohol) anchored maghemite nanoparticles designed for multi-stimuli triggered drug release

    NASA Astrophysics Data System (ADS)

    Liu, Ji; Detrembleur, Christophe; Debuigne, Antoine; de Pauw-Gillet, Marie-Claire; Mornet, Stéphane; Vander Elst, Luce; Laurent, Sophie; Labrugère, Christine; Duguet, Etienne; Jérôme, Christine

    2013-11-01

    Original core/corona nanoparticles composed of a maghemite core and a stimuli-responsive polymer coating made of poly(acrylic acid)-block-poly(vinyl alcohol) macromolecules were fabricated for drug delivery system (DDS) application. This kind of DDS aims to combine the advantage of stimuli-responsive polymer coating, in order to regulate the drug release behaviours under different conditions and furthermore, improve the biocompatibility and in vivo circulation half-time of the maghemite nanoparticles. Drug loading capacity was evaluated with methylene blue (MB), a cationic model drug. The triggered release of MB was studied under various stimuli such as pH, ionic strength and temperature. Local heating generated under alternating magnetic field (AMF) application was studied, and remotely AMF-triggered release was also confirmed, while a mild heating-up of the release medium was observed. Furthermore, their potential application as magnetic resonance imaging (MRI) contrast agents was explored via relaxivity measurements and acquisition of T2-weighted images. Preliminary studies on the cytotoxicity against mouse fibroblast-like L929 cell line and also their cellular uptake within human melanoma MEL-5 cell line were carried out. In conclusion, this kind of stimuli-responsive nanoparticles appears to be promising carriers for delivering drugs to some tumour sites or into cellular compartments with an acidic environment.Original core/corona nanoparticles composed of a maghemite core and a stimuli-responsive polymer coating made of poly(acrylic acid)-block-poly(vinyl alcohol) macromolecules were fabricated for drug delivery system (DDS) application. This kind of DDS aims to combine the advantage of stimuli-responsive polymer coating, in order to regulate the drug release behaviours under different conditions and furthermore, improve the biocompatibility and in vivo circulation half-time of the maghemite nanoparticles. Drug loading capacity was evaluated with methylene

  16. Stereocomplexation of low molecular weight poly(L-lactic acid) and high molecular weight poly(D-lactic acid), radiation crosslinking PLLA/PDLA stereocomplexes and their characterization

    NASA Astrophysics Data System (ADS)

    Quynh, Tran Minh; Mai, Hoang Hoa; Lan, Pham Ngoc

    2013-02-01

    Poly(L-lactic acid)s (PLLAx) were synthesized from L-lactic acid by polycondensation. Different stereocomplexes were also obtained with equimolar mixtures of synthesized PLLAx and a commercial PDLA. The stereocomplexes were crosslinked with triallyl isocyanurate (TAIC) by gamma irradiation. Crosslinking density increased with radiation doses, the heavier the crosslinking network, the lower its swelling degree. The crosslinking structures were introduced in the stereocomplexes inhibiting the mobility for crystallization of PLLA molecules. Thermal and mechanical properties of PLA stereocomplexes were remarkably enhanced by radiation induced crosslinking. PLA stereocomplex does not seem to be degraded by PLLA degrading microorganisms existing in compost at room temperature, but the synthesized PLLA was significantly degraded.

  17. Poly(α-hydroxy alkanoic acid)s derived from α-amino acids.

    PubMed

    Cohen-Arazi, Naomi; Domb, Abraham J; Katzhendler, Joshua

    2013-12-01

    Biodegradable polyesters derived from hydrophobic amino acids are synthesized by various techniques, resulting in a wide range of molecular weights. The polymers are prepared via a) direct condensation with p-toluenesulfonic acid (PTSA) as catalyst, b) ring-opening polymerization (ROP) of O-carboxyanhydrides, and c) ROP of cyclic dilactones. The polymers obtained by the first method reach a molecular weight ranging from 1000 to 3000 Da, whereas those formed by the second and third method yield extended molecular weights of 15000-30000 Da. The purity of the monomers as well as their steric bulkiness are key factors affecting the polymerizability of cyclic monomers by ROP. Other parameters such as spatial ring alignment and proximity organization may also play a role.

  18. The regulatory effect of citric acid on the co-production of poly(ε-lysine) and poly(L-diaminopropionic acid) in Streptomyces albulus PD-1.

    PubMed

    Xia, Jun; Xu, Zhaoxian; Xu, Hong; Feng, Xiaohai; Bo, Fangfang

    2014-10-01

    Streptomyces albulus PD-1 can co-produce antimicrobial homo-polymers poly(ε-lysine) (ε-PL) and poly(L-diaminopropionic acid) (PDAP). In this study, a novel feeding strategy of citric acid coupled with glucose-(NH4)2SO4 feeding was employed to S. albulus PD-1. When the pH of the culture broth dropped to 4.0, the feeding solution was added continuously to maintain the concentrations of glucose and citric acid at 10 and 4 g L(-1), respectively. As a result, the final concentration of ε-PL increased from 21.7 to 29.7 g L(-1) and the final concentration of PDAP decreased from 4.8 to 3.2 g L(-1). Assays on intracellular nucleotide levels and key enzyme activities were performed to elucidate the underlying regulation mechanism. The addition of citric acid increased NADH/NAD(+) ratio and decreased intracellular ATP level; meanwhile, the activities of pyruvate kinase, citrate synthase and isocitrate dehydrogenase decreased while aspartate aminotransferase activity increased. Therefore, we deduced that citric acid feeding resulted in metabolic flux redistribution at the node of phosphoenolpyruvate; the metabolic pathway from phosphoenolpyruvate directed into tricarboxylic acid cycle was weakened and thus PDAP production was inhibited. On the other hand, the metabolic pathway from phosphoenolpyruvate directed into oxaloacetate and L-aspartate was enhanced, thereby improving ε-PL production. This fermentation strategy may be potentially useful in ε-PL production because it can effectively inhibit the formation of by-products, such as PDAP.

  19. Biocompatibility and bone-repairing effects: comparison between porous poly-lactic-co-glycolic acid and nano-hydroxyapatite/poly(lactic acid) scaffolds.

    PubMed

    Zong, Chen; Qian, Xiaodan; Tang, Zihua; Hu, Qinghong; Chen, Jiarong; Gao, Changyou; Tang, Ruikang; Tong, Xiangmin; Wang, Jinfu

    2014-06-01

    Copolymer composite scaffolds and bioceramic/polymer composite scaffolds are two representative forms of composite scaffolds used for bone tissue engineering. Studies to compare biocompatibility and bone-repairing effects between these two scaffolds are significant for selecting or improving the scaffold for clinical application. We prepared two porous scaffolds comprising poly-lactic-acid/poly-glycolic-acid (PLGA) and poly-lactic-acid/nano-hydroxyapatite (nHAP/PLA) respectively, and examined their biocompatibility with human bone marrow-derived mesenchymal stem cells (hMSCs) through evaluating adhesion, proliferation and osteogenic differentiation potentials of hMSCs in the scaffold. Then, the PLGA scaffold with hMSCs (PM construct) and the nHAP/PLA scaffold with hMSCs (HPM construct) were transplanted into the rat calvarial defect areas to compare their effects on the bone reconstruction. The results showed that the nHAP/PLA scaffold was in favor of adhesion, matrix deposition and osteogenic differentiation of hMSCs. For in vivo transplantation, both HPM and PM constructs led to mineralization and osteogenesis in the defect area of rat. However, the area grafted with PM construct showed a better formation of mature bone than that with HPM construct. In addition, the evaluation of in vitro and in vivo degradation indicated that the degradation rate of nHAP/PLA scaffold was much lower than that of PLGA scaffold. It is inferred that the lower degradation of nHAP/PLA scaffold should result in its inferior bone reconstruction in rat calvaria. Therefore, the preparation of an ideal composite scaffold for bone tissue engineering should be taken into account of the balance between its biocompatibility, degradation rate, osteoconductivity and mechanical property.

  20. Crosslinked carboxymethylchitosan-g-poly(acrylic acid) copolymer as a novel superabsorbent polymer.

    PubMed

    Chen, Yu; Tan, Hui-min

    2006-05-22

    A novel carboxymethylchitosan-g-poly(acrylic acid) (CMCTS-g-PAA) superabsorbent polymer was prepared through graft polymerization of acrylic acid onto the chain of carboxymethylchitosan and subsequent crosslinking. It was demonstrated by FTIR spectroscopy that acrylic acid had been graft polymerized with carboxymethylchitosan. The thermal stability of the polymer was characterized by thermogravimetric analysis. By studying the swelling ratio of the polymer synthesized under different conditions, optimization conditions were found for a polymer with the highest swelling ratio. The rate of water absorption of the polymer was high, and the swelling of the polymer fitted the process of first dynamics. The swelling ratio of the polymer was pH-dependent.

  1. SYNTHESIS AND CHARACTERIZATION OF SUBSTITUTED POLY(STYRENE)-b-POLY(ACRYLIC ACID) BLOCK COPOLYMER MICELLES

    SciTech Connect

    Pickel, Deanna L; Pickel, Joseph M; Devenyi, Jozsef; Britt, Phillip F

    2009-01-01

    Block copolymer micelle synthesis and characterization has been extensively studied. In particular, most studies have focused on the properties of the hydrophilic corona due to the micelle corona structure s impact on the biodistribution and biocompatibility. Unfortunately, less attention has been given to the effect of the core block on the micelle stability, morphology, and the rate of diffusion of small molecules from the core. This investigation is focused on the synthesis of block copolymers composed of meta-substituted styrenes and acrylic acid by Atom Transfer Radical Polymerization. Micelles with cores composed of substituted styrenes having Tgs ranging from -30 to 100 oC have been prepared and the size and shape of these micelles were characterized by Static and Dynamic Light Scattering and TEM. In addition, the critical micelle concentration and rate of diffusion of small molecules from the core were determined by fluorimetry using pyrene as the probe.

  2. Biosynthesis of highly pure poly-γ-glutamic acid for biomedical applications.

    PubMed

    Pereira, Catarina Leite; Antunes, Joana Costa; Gonçalves, Raquel Madeira; Ferreira-da-Silva, Frederico; Barbosa, Mário Adolfo

    2012-07-01

    The remarkable properties of poly-aminoacids, mainly their biocompatibility and biodegradability, have prompted an increasing interest in these polymers for biomedical applications. Poly-γ-glutamic acid (γ-PGA) is one of the most interesting poly-aminoacids with potential applications as a biomaterial. Here we describe the production and characterization of γ-PGA by Bacillus subtilis natto. The γ-PGA was produced with low molecular weight (10-50 kDa), high purity grade (>99 %) and a D: -/L: -glutamate ratio of 50-60/50-40 %. To evaluate the feasibility of using this γ-PGA as a biomaterial, chitosan (Ch)/γ-PGA nanoparticles were prepared by the coacervation method at pH ranging from 3.0 to 5.0, with dimensions in the interval 214-221 nm with a poly-dispersion index of ca. 0.2. The high purity of γ-PGA produced by this method, which is firstly described here, renders this biopolymer suitable for biomedical applications. Moreover, the Ch/γ-PGA nanocomplexes developed in this investigation can be combined with biologically active substances for their delivery in the organism. The fact that the assembly between Ch and γ-PGA relies on electrostatic interactions enables addition of other molecules that can be released into the medium through changes from acidic to physiological pH, without loss in biological activity.

  3. Composite poly-L-lactic acid/poly-(α,β)-DL-aspartic acid/collagen nanofibrous scaffolds for dermal tissue regeneration.

    PubMed

    Ravichandran, Rajeswari; Venugopal, Jayarama Reddy; Sundarrajan, Subramanian; Mukherjee, Shayanti; Sridhar, Radhakrishnan; Ramakrishna, Seeram

    2012-08-01

    Tissue engineering scaffolds for skin tissue regeneration is an ever expounding area of research, as the products that meet the necessary requirements are far and elite. The nanofibrous poly-L-lactic acid/poly-(α,β)-DL-aspartic acid/Collagen (PLLA/PAA/Col I&III) scaffolds were fabricated by electrospinning and characterized by SEM, contact angle and FTIR analysis for skin tissue regeneration. The cell-scaffold interactions were analyzed by cell proliferation and their morphology observed in SEM. The results showed that the cell proliferation was significantly increased (p≤0.05) in PLLA/PAA/Col I&III scaffolds compared to PLLA and PLLA/PAA nanofibrous scaffolds. The abundance and accessibility of adipose derived stem cells (ADSCs) may prove to be novel cell therapeutics for dermal tissue regeneration. The differentiation of ADSCs was confirmed using collagen expression and their morphology by CMFDA dye extrusion technique. The current study focuses on the application of PLLA/PAA/Col I&III nanofibrous scaffolds for skin tissue engineering and their potential use as substrate for the culture and differentiation of ADSCs. The objective for inclusion of a novel cell binding moiety like PAA was to replace damaged extracellular matrix and to guide new cells directly into the wound bed with enhanced proliferation and overall organization. This combinatorial epitome of PLLA/PAA/Col I&III nanofibrous scaffold with stem cell therapy to induce the necessary paracrine signalling effect would favour faster regeneration of the damaged skin tissues.

  4. Molecular Dynamics Simulations of Adsorption of Poly(acrylic acid) and Poly(methacrylic acid) on Dodecyltrimethylammonium Chloride Micelle in Water: Effect of Charge Density.

    PubMed

    Sulatha, Muralidharan S; Natarajan, Upendra

    2015-09-24

    We have investigated the interaction of dodecyltrimethylammonium chloride (DoTA) micelle with weak polyelectrolytes, poly(acrylic acid) and poly(methacrylic acid). Anionic as well as un-ionized forms of the polyelectrolytes were studied. Polyelectrolyte-surfactant complexes were formed within 5-11 ns of the simulation time and were found to be stable. Association is driven purely by electrostatic interactions for anionic chains whereas dispersion interactions also play a dominant role in the case of un-ionized chains. Surfactant headgroup nitrogen atoms are in close contact with the carboxylic oxygens of the polyelectrolyte chain at a distance of 0.35 nm. In the complexes, the polyelectrolyte chains are adsorbed on to the hydrophilic micellar surface and do not penetrate into the hydrophobic core of the micelle. Polyacrylate chain shows higher affinity for complex formation with DoTA as compared to polymethacrylate chain. Anionic polyelectrolyte chains show higher interaction strength as compared to corresponding un-ionized chains. Anionic chains act as polymeric counterion in the complexes, resulting in the displacement of counterions (Na(+) and Cl(-)) into the bulk solution. Anionic chains show distinct shrinkage upon adsorption onto the micelle. Detailed information about the microscopic structure and binding characteristics of these complexes is in agreement with available experimental literature.

  5. Lipase-catalyzed enantioselective synthesis of (R,R)-lactide from alkyl lactate to produce PDLA (poly D-lactic acid) and stereocomplex PLA (poly lactic acid).

    PubMed

    Jeon, Byoung Wook; Lee, Jumin; Kim, Hyun Sook; Cho, Dae Haeng; Lee, Hyuk; Chang, Rakwoo; Kim, Yong Hwan

    2013-10-20

    R-lactide, a pivotal monomer for the production of poly (D-lactic acid) (PDLA) or stereocomplex poly (lactic acid) (PLA) was synthesized from alkyl (R)-lactate through a lipase-catalyzed reaction without racemization. From among several types of lipase, only lipase B from Candida antarctica (Novozym 435; CAL-B) was effective in the reaction that synthesized (R,R)-lactide. Enantiopure (R,R)-lactide, which consisted of over 99% enantiomeric excess, was synthesized from methyl (R)-lactate through CAL-B catalysis. Removal of the methanol by-product was critical to obtain a high level of lactide conversion. The (R,R)-lactide yield was 56% in a reaction containing 100 mg of Novozym 435, 10 mM methyl (R)-lactate and 1500 mg of molecular sieve 5A in methyl tert-butyl ether (MTBE). The important monomer (R,R)-lactide that is required for the production of the widely recognized bio-plastic PDLA and the PLA stereocomplex can be obtained using this novel synthetic method.

  6. A study on reactive blending of (poly lactic acid) and poly (butylene succinate co adipate)

    NASA Astrophysics Data System (ADS)

    Bureepukdee, C.; Suttiruengwong, S.; Seadan, M.

    2015-07-01

    This research aims to study the blending of Polylactic acid (PLA) and Polybutylene succinate co adipate (PBSA) in order to understand the role of peroxide in free radical reaction on the compatibilization between these two biodegradable polyesters. Various ratios of PLA/PBSA blends with and without reactive agents were prepared in the twin screw extruder. Two types of peroxides, Di (tert-butylperoxyisopropyl) benzene (DTBP) and 2, 5-Dimethyl-2, 5-(t-butylperoxy) hexane (DTBH), were used with various concentrations to compare. From the torques measurement, DTBP was more reactive with PLA and PBSA than DTBH. PLA and PBSA 80:20, 60:40, 50:50, 40:60, and 20:80% by weight were melt-blended in a twin screw extruder. The reactive polymer blends were also prepared for the same ratios of the blends with addition of 0.08 and 0.1 phr of DTBP. The mechanical, thermal, rheological, and morphological properties were investigated. The impact strengths of the non-reactive blend increased with the increasing in PBSA content. The optimal impact strength was obtained at 40%wt of PBSA with 0.1 phr of DTBP. Adding 0.08 and 0.1 phr of DTBP led to the co continuous phase morphology of PLA/PBSA blends. The per cent crystallinity of PLA increased when blended with PBSA. PBSA might induce the crystallization of PLA.

  7. Preparation of Poly Acrylic Acid-Poly Acrylamide Composite Nanogels by Radiation Technique

    PubMed Central

    Ghorbaniazar, Parisa; Sepehrianazar, Amir; Eskandani, Morteza; Nabi-Meibodi, Mohsen; Kouhsoltani, Maryam; Hamishehkar, Hamed

    2015-01-01

    Purpose: Nanogel, a nanoparticle prepared from a cross-linked hydrophilic polymer network, has many biomedical applications. A radiation technique has recently been introduced as one of the appropriate methods for the preparation of polymeric nanogels due to its additive-free initiation and easy control procedure. Methods: We have investigated the formation of nano-sized polymeric gels, based on the radiation-induced inter- and intra-molecular cross-linking of the inter-polymer complex (IPC) of polyacrylamide (PAAm) and polyacrylic acide (PAAc). Results: The results indicated that the prepared polymeric complex composed of PAAm and PAAc was converted into nanogel by irradiation under different doses (1, 3, 5 and 7 kGy). This was due to inter- and intra-molecular cross-linking at the range of 446-930 nm as characterized by the photon correlation spectroscopy method. Increasing the irradiation dose reduced the size of nanoparticles to 3 kGy; however, the higher doses increased the size and size distribution. Scanning electron microscopy images indicated the nanogel formation in the reported size by particle size and showed the microcapsule structure of the prepared nanogels. Biocompatibility of nanogels were assessed and proved by MTT assay. Conclusion: It was concluded that low dose irradiation can be successfully applied for nanometre-ranged hydrogel. PMID:26236667

  8. Poly(Vinyl Alcohol)/Poly(Acrylic Acid) Hydrogel in a dc Electric Field: Swelling, Shape Change, and Actuation Characteristics

    PubMed Central

    2014-01-01

    Poly(vinyl alcohol) (PVA)/Poly(acrylic acid) (PAA) hydrogel can be utilized as a biomimetic actuator and coating material for tissue-implant interface, when employing an electrical stimulus. The swelling, shape change, and actuation characteristics of PVA/PAA hydrogel in a range of dc electrical fields were determined to find the optimal electric field for the hydrogel application as biomimetic actuator and coating materials. The hydrogel samples were prepared by dissolving PVA and PAA in deionized water at 4 wt% and mixed together at 1:1 ratio. Two custom made experimental setups were fabricated; one used for the measurement of swelling ratio of the hydrogels; and the other used for the shape changes or actuation characteristics of the hydrogels. Swelling experiments show increased swelling ratios of the hydrogel due to 10 V, 20 V, and 30 V electric fields. The rate of increment of the swelling ratio of hydrogel samples under 10V was higher compare to those samples under 20 V and 30 V. The width and height changes of rectangular shapes and maximum deflection along the length of hydrogel sample due to a range of electric fields (0-30V) were measured using an optical microscope. Incremental shape change up to a specific threshold value (around 10V) was observed due to electric stimulus. Electrostatic actuation pressure of hydrogel samples under 10V was higher compare to those samples under 20 V and 30 V. These results suggested that optimal performance of PVA/PAA hydrogel can be achieved around 10V. PMID:25478321

  9. Poly(lactic-co-glycolic) acid-controlled-release systems: experimental and modeling insights.

    PubMed

    Hines, Daniel J; Kaplan, David L

    2013-01-01

    Poly(lactic-co-glycolic acid) (PLGA) has been the most successful polymeric biomaterial used in controlled drug delivery systems. There are several different chemical and physical properties of PLGA that impact the release behavior of drugs from PLGA delivery devices. These properties must be considered and optimized in the formulation of drug release devices. Mathematical modeling is a useful tool for identifying, characterizing, and predicting mechanisms of controlled release. The advantages and limitations of poly(lactic-co-glycolic acid) for controlled release are reviewed, followed by a review of current approaches in controlled-release technology that utilize PLGA. Mathematical modeling applied toward controlled-release rates from PLGA-based devices also will be discussed to provide a complete picture of a state-of-the-art understanding of the control that can be achieved with this polymeric system, as well as the limitations.

  10. Poly (lactic-co-glycolic acid) controlled release systems: experimental and modeling insights

    PubMed Central

    Hines, Daniel J.; Kaplan, David L.

    2013-01-01

    Poly-lactic-co-glycolic acid (PLGA) has been the most successful polymeric biomaterial for use in controlled drug delivery systems. There are several different chemical and physical properties of PLGA that impact the release behavior of drugs from PLGA delivery devices. These properties must be considered and optimized in drug release device formulation. Mathematical modeling is a useful tool for identifying, characterizing, and predicting the mechanisms of controlled release. The advantages and limitations of poly (lactic-co-glycolic acid) for controlled release are reviewed, followed by a review of current approaches in controlled release technology that utilize PLGA. Mathematical modeling applied towards controlled release rates from PLGA-based devices will also be discussed to provide a complete picture of state of the art understanding of the control achievable with this polymeric system, as well as the limitations. PMID:23614648

  11. Surface proton transport of fully protonated poly(aspartic acid) thin films on quartz substrates

    NASA Astrophysics Data System (ADS)

    Nagao, Yuki; Kubo, Takahiro

    2014-12-01

    Thin film structure and the proton transport property of fully protonated poly(aspartic acid) (P-Asp100) have been investigated. An earlier study assessed partially protonated poly(aspartic acid), highly oriented thin film structure and enhancement of the internal proton transport. In this study of P-Asp100, IR p-polarized multiple-angle incidence resolution (P-MAIR) spectra were measured to investigate the thin film structure. The obtained thin films, with thicknesses of 120-670 nm, had no oriented structure. Relative humidity dependence of the resistance, proton conductivity, and normalized resistance were examined to ascertain the proton transport property of P-Asp100 thin films. The obtained data showed that the proton transport of P-Asp100 thin films might occur on the surface, not inside of the thin film. This phenomenon might be related with the proton transport of the biological system.

  12. Biomimetic niche for neural stem cell differentiation using poly-L-lysine/hyaluronic acid multilayer films.

    PubMed

    Lee, I-Chi; Wu, Yu-Chieh; Cheng, En-Ming; Yang, Wen-Ting

    2015-05-01

    Polyelectrolyte multilayer films have been suggested as tunable substrates with flexible surface properties that can modulate cell behavior. However, these films' biological effects on neural stem/progenitor cells have rarely been studied. Herein, biomimetic multilayer films composed of hyaluronic acid and poly-L-lysine were chosen to mimic the native extracellular matrix niche of brain tissue and were evaluated for their inductive effects, without the addition of chemical factors. Because neural stem/progenitor cells are sensitive to substrate properties, it is important that this system provides control over the surface charge, and slight stiffness variations are also possible. Both of these factors affect neural stem/progenitor cell differentiation. The results showed that neural stem/progenitor cells were induced to differentiate on the poly-L-lysine/hyaluronic acid multilayer films with 0.5-4 alternating layers. In addition, the neurite outgrowth length was regulated by the surface charge of the terminal layer but did not increase with the layer number. In contrast, the quantity of differentiated neurons was enhanced slightly as the number of layers increased but was not affected by the surface charge of the terminal layer. In sum, material pairs in the form of native poly-L-lysine/hyaluronic acid films achieved important targets for neural regenerative medicine, including enhancement of the neurite outgrowth length, regulation of neuron differentiation, and the formation of a network. These extracellular matrix-mimetic poly-L-lysine/hyaluronic acid multilayer films may provide a versatile platform that could be useful for surface modification for applications in neural engineering.

  13. The "skinny"on Sculptra: a practical primer to volumization with poly-L-lactic acid.

    PubMed

    Palm, Melanie; Chayavichitsilp, Pamela

    2012-09-01

    Poly-L-lactic acid (PLLA) is a biostimulatory agent that can correct bony and soft tissue facial deficiencies by producing gradual volume restoration. Proper patient selection and clear expectations are important to treatment success. Correct product preparation, injection technique, and patient follow-up correlates with increased patient safety, outcomes, and satisfaction. Alone, or in combination with other rejuvenative procedures, Sculptra® provides longer-lasting improvement to signs of facial aging.

  14. Children and IC

    MedlinePlus

    ... well as his or her teachers, principal, school nurse, gym teacher, etc. Your child’s symptoms may be ... Out IC How to Schedule an IC Advocacy District Visit IC Advocates in Action Spur Research Funding ...

  15. Pregnancy and IC

    MedlinePlus

    ... hospital personnel (such as medical students or student nurses) to observe your birth process Whether you will ... Out IC How to Schedule an IC Advocacy District Visit IC Advocates in Action Spur Research Funding ...

  16. Biocatalyzed approach for the surface functionalization of poly(L-lactic acid) films using hydrolytic enzymes.

    PubMed

    Pellis, Alessandro; Acero, Enrique Herrero; Weber, Hansjoerg; Obersriebnig, Michael; Breinbauer, Rolf; Srebotnik, Ewald; Guebitz, Georg M

    2015-09-01

    Poly(lactic acid) as a biodegradable thermoplastic polyester has received increasing attention. This renewable polyester has found applications in a wide range of products such as food packaging, textiles and biomedical devices. Its major drawbacks are poor toughness, slow degradation rate and lack of reactive side-chain groups. An enzymatic process for the grafting of carboxylic acids onto the surface of poly(L-lactic acid) (PLLA) films was developed using Candida antarctica lipase B as a catalyst. Enzymatic hydrolysis of the PLLA film using Humicola insolens cutinase in order to increase the number of hydroxyl and carboxylic groups on the outer polymer chains for grafting was also assessed and showed a change of water contact angle from 74.6 to 33.1° while the roughness and waviness were an order of magnitude higher in comparison to the blank. Surface functionalization was demonstrated using two different techniques, (14) C-radiochemical analysis and X-ray photoelectron spectroscopy (XPS) using (14) C-butyric acid sodium salt and 4,4,4-trifluorobutyric acid as model molecules, respectively. XPS analysis showed that 4,4,4-trifluorobutyric acid was enzymatically coupled based on an increase of the fluor content from 0.19 to 0.40%. The presented (14) C-radiochemical analyses are consistent with the XPS data indicating the potential of enzymatic functionalization in different reaction conditions.

  17. Poly(N-vinylimidazole/ethylene glycol dimethacrylate) for the purification and isolation of phenolic acids.

    PubMed

    Schemeth, Dieter; Noël, Jean-Christophe; Jakschitz, Thomas; Rainer, Matthias; Tessadri, Richard; Huck, Christian W; Bonn, Günther K

    2015-07-23

    In this study we report the novel polymeric resin poly(N-vinyl imidazole/ethylene glycol dimethacrylate) for the purification and isolation of phenolic acids. The monomer to crosslinker ratio and the porogen composition were optimized for isolating phenolic acids diluted in acetonitrile at normal phase chromatography conditions, first. Acetonitrile serves as polar, aprotic solvent, dissolving phenolic acids but not interrupting interactions with the stationary phase due to the approved Hansen solubility parameters. The optimized resin demonstrated high loading capacities and adsorption abilities particularly for phenolic acids in both, acetonitrile and aqueous solutions. The adsorption behavior of aqueous standards can be attributed to ion exchange effects due to electrostatic interactions between protonated imidazole residues and deprotonated phenolic acids. Furthermore, adsorption experiments and subsequent curve fittings provide information of maximum loading capacities of single standards according to the Langmuir adsorption model. Recovery studies of the optimized polymer in the normal-phase and ion-exchange mode illustrate the powerful isolation properties for phenolic acids and are comparable or even better than typical, commercially available solid phase extraction materials. In order to prove the applicability, a highly complex extract of rosemary leaves was purified by poly(N-vinyl imidazole/ethylene glycol dimethacrylate) and the isolated compounds were identified using UHPLC-qTOF-MS.

  18. A protein delivery system: biodegradable alginate-chitosan-poly(lactic-co-glycolic acid) composite microspheres.

    PubMed

    Zheng, Cai-Hong; Gao, Jian-Qing; Zhang, Ye-Ping; Liang, Wen-Quan

    2004-10-29

    In the present study we developed alginate-chitosan-poly(lactic-co-glycolic acid) (PLGA) composite microspheres to elevate protein entrapment efficiency and decrease its burst release. Bovine serum albumin (BSA), which used as the model protein, was entrapped into the alginate microcapsules by a modified emulsification method in an isopropyl alcohol-washed way. The rapid drug releases were sustained by chitosan coating. To obtain the desired release properties, the alginate-chitosan microcapsules were further incorporated in the PLGA to form the composite microspheres. The average diameter of the composite microcapsules was 31+/-9microm and the encapsulation efficiency was 81-87%, while that of conventional PLGA microspheres was just 61-65%. Furthermore, the burst releases at 1h of BSA entrapped in composite microspheres which containing PLGA (50:50) and PLGA (70:30) decreased to 24% and 8% in PBS, and further decreased to 5% and 2% in saline. On the contrary, the burst releases of conventional PLGA microspheres were 48% and 52% in PBS, respectively. Moreover, the release profiles could be manipulated by regulating the ratios of poly(lactic acid) to poly(glycolic acid) in the composite microspheres.

  19. Phenolic acid-based poly(anhydride-esters) as antioxidant biomaterialsa

    PubMed Central

    Prudencio, Almudena; Faig, Jonathan J.; Song, MinJung

    2015-01-01

    Poly(anhydride-esters) comprised of naturally occurring, non-toxic phenolic acids, namely syringic and vanillic acid, with antioxidant properties were prepared via solution polymerization methods. Polymer and polymer precursor physiochemical properties were characterized, including polymer molecular weight and thermal properties. In vitro release studies illustrated that polymer hydrolytic degradation was influenced by relative hydrophobicity and degree of methoxy substitution of the phenolic acids. Further, the released phenolic acids were found to maintain antioxidant potency relative to free phenolic acid controls as determined by a 2,2-diphenyl-1-picrylhydrazyl assay. Polymer cytotoxicity was assessed with L929 fibroblasts in polymer-containing media; appropriate cell morphology and high fibroblast proliferation were obtained for the polymers at the lower concentrations. These polymers deliver non-cytotoxic levels of naturally occurring antioxidants, which could be efficacious in topical delivery of antioxidant therapies. PMID:26425923

  20. A simple and robust method for pre-wetting poly (lactic-co-glycolic) acid microspheres.

    PubMed

    Wright, Bernice; Parmar, Nina; Bozec, Laurent; Aguayo, Sebastian D; Day, Richard M

    2015-08-01

    Poly (lactic-co-glycolic) acid microspheres are amenable to a number of biomedical procedures that support delivery of cells, drugs, peptides or genes. Hydrophilisation or wetting of poly (lactic-co-glycolic) acid are an important pre-requisites for attachment of cells and can be achieved via exposure to plasma oxygen or nitrogen, surface hydrolysis with NaOH or chloric acid, immersion in ethanol and water, or prolonged incubation in phosphate buffered saline or cell culture medium. The aim of this study is to develop a simple method for wetting poly (lactic-co-glycolic) acid microspheres for cell delivery applications. A one-step ethanol immersion process that involved addition of serum-supplemented medium and ethanol to PLGA microspheres over 30 min-24 h is described in the present study. This protocol presents a more efficient methodology than conventional two-step wetting procedures. Attachment of human skeletal myoblasts to poly (lactic-co-glycolic) acid microspheres was dependent on extent of wetting, changes in surface topography mediated by ethanol pre-wetting and serum protein adsorption. Ethanol, at 70% (v/v) and 100%, facilitated similar levels of wetting. Wetting with 35% (v/v) ethanol was only achieved after 24 h. Pre-wetting (over 3 h) with 70% (v/v) ethanol allowed significantly greater (p ≤ 0.01) serum protein adsorption to microspheres than wetting with 35% (v/v) ethanol. On serum protein-loaded microspheres, greater numbers of myoblasts attached to constructs wetted with 70% ethanol than those partially wetted with 35% (v/v) ethanol. Microspheres treated with 70% (v/v) ethanol presented a more rugose surface than those treated with 35% (v/v) ethanol, indicating that more efficient myoblast adhesion to the former may be at least partially attributed to differences in surface structure. We conclude that our novel protocol for pre-wetting poly (lactic-co-glycolic) acid microspheres that incorporates biochemical and structural features

  1. Electrospraying and Electrospinning of Polymers for Biomedical Applications. Poly(Lactic-Co-Glycolic Acid) and Poly(Ethylene-Co-Vinylacetate). Appendix 2

    NASA Technical Reports Server (NTRS)

    Stitzel, Joel D.; Bowlin, Gary L.; Mansfield, Kevin; Wnek, Gary E.; Simpson, David G.

    2000-01-01

    Significant opportunities exist for the processing of polymers (homopolymers and blends) using electric fields. Specific attention is given here to electrospinning, but we note that electroaerosol formation and field-modulated film casting represent additional processing options. Of particular interest is the ability to generate polymer fibers of sub-micron dimensions using electrospinning, down to about 0.05 microns (50 nm), a size range that has been traditionally difficult to access. In our work, poly(lactic-co-glycolic acid), PLA/PGA, poly(lactic acid) PLA, and poly(ethylene-co-vinylacetate) (PEVA) have been deposited from solutions in methylene chloride or chloroform by electrospraying or electrospinning to afford morphologically tailored materials for tissue engineering and related applications. Low solution concentrations tend to favor electrostatic spraying ('electro-aerosolization') while higher concentrations lead to spinning on fibrous mats. Preliminary observations of muscle cell growth on PLA electrospun mats are reported.

  2. Biodegradability and biocompatibility study of poly(chitosan-g-lactic acid) scaffolds.

    PubMed

    Zhang, Zhe; Cui, Huifei

    2012-03-14

    A biodegradable, biocompatible poly(chitosan-g-lactic acid) (PCLA) scaffold was prepared and evaluated in vitro and in vivo. The PCLA scaffold was obtained by grafting lactic acid (LA) onto the amino groups on chitosan (CS) without a catalyst. The PCLA scaffolds were characterized by Fourier Transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The biodegradabilty was determined by mass loss in vitro, and degradation in vivo as a function of feed ratio of LA/CS. Bone marrow mesenchymal stem cell (BMSC) culture experiments and histological examination were performed to evaluate the PCLA scaffolds' biocompatibility. The results indicated that PCLA was promising for tissue engineering application.

  3. Structure and Proton Conductivity in Mixtures of Poly(acrylic acid) and Imidazole

    NASA Astrophysics Data System (ADS)

    Yang, Han-Chang; Griffin, Philip J.; Winey, Karen I.; University of Pennsylvania Team

    2015-03-01

    Proton conductivity in polymer electrolyte membranes (PEMs) typically involves water, which requires that during operation the humidity of the PEM be carefully controlled. In contrast, anhydrous protic polymer membranes promote proton transport by incorporating heterocyclic molecules, such as imidazole and its derivatives, into acid-containing polymers. In this work, we explore the interplay between nanoscale-structure and proton conduction of poly(acrylic acid) (PAA) blended at varying compositions with 2-ethyl-4-methylimidazole (EMI). We present the glass transition temperature from differential scanning calorimetry, morphology characterization from X-ray scattering, and proton conductivity from electrical impedance spectroscopy.

  4. Pluronic-poly (acrylic acid)-cysteine/Pluronic L121 mixed micelles improve the oral bioavailability of paclitaxel.

    PubMed

    Zhao, Yanli; Li, Yanli; Ge, Jianjun; Li, Na; Li, Ling-Bing

    2014-11-01

    The aim of the study is to synthesize a thiolated Pluronic copolymer, Pluronic-poly (acrylic acid)-cysteine copolymer, to construct a mixed micelle system with the Pluronic-poly (acrylic acid)-cysteine copolymer and Pluronic L121 (PL121) and to evaluate the potential of these mixed micelles as an oral drug delivery system for paclitaxel. Compared with Pluronic-poly (acrylic acid)-cysteine micelles, drug-loading capacity of Pluronic-poly (acrylic acid)-cysteine/PL121 mixed micelles was increased from 0.4 to 2.87%. In vitro release test indicated that Pluronic-poly (acrylic acid)-cysteine/PL121 mixed micelles exhibited a pH sensitivity. The permeability of drug-loaded micelles in the intestinal tract was studied with an in situ perfusion method in rats. The presence of verapamil and Pluronic both improved the intestinal permeability of paclitaxel, which further certified the inhibition effect of thiolated Pluronic on P-gp. In pharmacokinetic study, the area under the plasma concentration-time curve (AUC0→∞) of paclitaxel-loaded mixed micelles was four times greater than that of the paclitaxel solution (p < 0.05). In general, Pluronic-poly (acrylic acid)-cysteine/PL121 micelles were proven to be a potential oral drug delivery system for paclitaxel.

  5. Poly(vinylidene fluoride) Containing Phosphonic Acid as Anticorrosion Coating for Steel.

    PubMed

    Banerjee, Sanjib; Wehbi, Mohammad; Manseri, Abdellatif; Mehdi, Ahmad; Alaaeddine, Ali; Hachem, Ali; Ameduri, Bruno

    2017-02-22

    Vinylidene fluoride (VDF)-based copolymers bearing pendant phosphonic acid function for potential application as anticorrosion coatings were synthesized via free radical copolymerization of VDF with a new phosphorus containing 2-trifluoromethacrylate monomer, (dimethoxyphosphoryl)methyl 2-(trifluoromethyl)acrylate (MAF-DMP). MAF-DMP was prepared from 2-trifluoromethacrylic acid in 60% overall yield. Radical copolymerizations of VDF with MAF-DMP initiated by tert-amyl peroxy-2-ethylhexanoate at varying ([VDF]0/[MAF-DMP]0) feed ratios led to several poly(VDF-co-MAF-DMP) copolymers having different molar percentages of VDF (79-96%) and number-average molecular weights (Mn's) up to ca. 10 000 g mol(-1) in fair yields (47-53%). Determination of the composition and microstructure of all the synthesized copolymers was done by (1)H and (19)F NMR spectroscopies. The monomer reactivity ratios of this new VDF/MAF-DMP pair were also determined (rVDF = 0.76 ± 0.34 and rMAF-DMP = 0 at 74 °C). The resulting poly(VDF-co-MAF-DMP) copolymers exhibited high melting temperature (162-171 °C, with respect to the VDF content), and the degree of crystallinity reached up to 51%. Finally, the pendant dimethyl phosphonate ester groups of the synthesized poly(VDF-co-MAF-DMP) copolymer were quantitatively hydrolyzed, giving rise to novel phosphonic acid-functionalized PVDF (PVDF-PA). In comparison to hydrophobic poly(VDF-co-MAF-DMP) copolymers (the water contact angle, WCA, was 98°), the hydrophilic character of the PVDF-PA was found to be surprisingly rather pronounced, exhibiting low WCA (15°). Finally, steel plates coated with PVDF-PA displayed satisfactory anticorrosion properties under simulated seawater environment.

  6. Feasibility of antibody-poly(glutamic acid) complexes: preparation of high-concentration antibody formulations and their pharmaceutical properties.

    PubMed

    Izaki, Shunsuke; Kurinomaru, Takaaki; Maruyama, Takuya; Uchida, Takayuki; Handa, Kenji; Kimoto, Tomoaki; Shiraki, Kentaro

    2015-06-01

    Development of high-concentration antibody formulations for subcutaneous administration remains challenging. Recently, a precipitation-redissolution method was proposed to prepare suspensions or precipitates of salt-dissociable protein-poly(amino acid) complexes. To elucidate the utility of this method for protein therapy, we investigated the feasibility of a precipitation-redissolution method using poly(amino acid) for high-concentration antibody formulation. Omalizumab and adalimumab formulations of 150 mg/mL could be prepared using poly-l-glutamic acid (polyE) from low-concentration stock solutions. Enzyme-linked immunosorbent assay, circular dichroism, and size-exclusion chromatography revealed that the formation of antibody-polyE complex and precipitation-redissolution process did not significantly affect the immunoreactivity or secondary structure of the antibodies. The precipitation-redissolution method was less time-consuming and more effective than lyophilization-redissolution, evaporation-redissolution, and ultrafiltration from the viewpoint of final yield. Scalability was confirmed from 400 μL to 1.0 L. The general toxicity and pharmacokinetic profiles of the antibody-polyE complex formulations were similar to those of conventional antibody formulations. These results suggested that the precipitation-redissolution method using poly(amino acid) has great potential as a concentration method for antibody formulation and medicinal use.

  7. Structural characterization of hydrated poly(aspartic acid) sodium and poly(aspartic acid) sodium/poly(vinyl alcohol) blends by high-resolution solid-state 23Na NMR

    NASA Astrophysics Data System (ADS)

    Wang, P.; Ando, I.

    1999-09-01

    The structure of hydrated poly(aspartic acid) sodium (PAANa) and in blended PAANa, which was blended with poly(vinyl alcohol) (PVA), is characterized by means of high-resolution solid-state 23Na NMR. There are two peaks in dried pure PAANa, which are assigned to associated ions (about -16 ppm) and isolated ions or end group ions of PAANa (7.2 ppm), respectively. With an increase in hydration, the 23Na chemical shifts of these two peaks are changed to tend toward 0 ppm, and the line width at half the height of the 23Na resonance decreases. In contrast, in the blended samples, the 23Na resonance shapes and chemical shift values are significantly changed depending on the ratio of the PAANa/PVA blends and the temperature. On the basis of these experimental results, the structure of the blends was elucidated.

  8. Electroactive self-doped poly(amic acid) with oligoaniline and sulfonic acid groups: synthesis and electrochemical properties.

    PubMed

    Chi, Maoqiang; Wang, Shutao; Liang, Yuan; Chao, Danming; Wang, Ce

    2014-06-01

    A novel poly(amic acid) with pendant aniline tetramer and sulfonic acid groups (ESPAA) was synthesized by ternary polymerization and characterized by Fourier-transform infrared spectra, ((1))H NMR and gel permeation chromatography. The polymer showed good thermal stability and excellent solubility in the common organic solvents. The electrochemical properties were investigated carefully on a CHI 660A Electrochemical Workstation. The polymer displayed good electroactivity in acid, neutral and even in alkaline solutions (pH=1-10) due to the self-doping effect between aniline tetramer and sulfonic/carboxylic acid groups. It also exhibited satisfactory electrochromic performance with high contrast value, acceptable coloration efficiency and fast switching time in the range of pH=1-9.

  9. Freeze dried chitosan/ poly-(glutamic acid) microparticles for intestinal delivery of lansoprazole.

    PubMed

    Singh, Mangla Nand; Yadav, Hemant K S; Ram, Munshi; Shivakumar, H G

    2012-01-01

    Lansoprazole sodium is a proton pump inhibitor used in treating gastroesophageal reflux disease (GERD). It is highly acid-labile and presents many formulation challenges. Therefore, this drug needs to be protected from the harsh environment in the stomach. In order to achieve this, a pH-sensitive microparticle system composed of chitosan and γ- poly-(glutamic acid) was prepared and loaded with Lansoprazole. The prepared microparticles were not stable in gastric pH. To overcome this problem microparticles were freez-dried and filled in an enteric-coated capsule. Upon oral administration, the enteric-coated capsule remained intact in the acidic environment of the stomach, but dissolved rapidly in the distal segment of the GIT. Consequently, all the microparticles loaded in the capsule were brought into the intestine, thus enhancing the intestinal absorption of drug. Drug encapsulation efficiency of formulation F3 was found to be 82.82 % and in vitro release of prepared formulation F3 was found to be 94% after 8 h of dissolution in 7.4 pH phosphate buffer. FTIR and DSC studies showed no interaction between the drug and polymer. The formulation showed good swelling property. SEM photographs showed that microparticles are spherical and lies in size range of 300-400 μm. From the above, it can be concluded that the prepared chitosan/ γ-poly-(glutamic acid) microparticles can be used as carriers for the intestinal delivery of acid liable drugs such as lansoprazole.

  10. Direct laser writing of synthetic poly(amino acid) hydrogels and poly(ethylene glycol) diacrylates by two-photon polymerization.

    PubMed

    Käpylä, Elli; Sedlačík, Tomáš; Aydogan, Dogu Baran; Viitanen, Jouko; Rypáček, František; Kellomäki, Minna

    2014-10-01

    The additive manufacturing technique of direct laser writing by two-photon polymerization (2PP-DLW) enables the fabrication of three-dimensional microstructures with superior accuracy and flexibility. When combined with biomimetic hydrogel materials, 2PP-DLW can be used to recreate the microarchitectures of the extracellular matrix. However, there are currently only a limited number of hydrogels applicable for 2PP-DLW. In order to widen the selection of synthetic biodegradable hydrogels, in this work we studied the 2PP-DLW of methacryloylated and acryloylated poly(α-amino acid)s (poly(AA)s). The performance of these materials was compared to widely used poly(ethylene glycol) diacrylates (PEGdas) in terms of polymerization and damage thresholds, voxel size, line width, post-polymerization swelling and deformation. We found that both methacryloylated and acryloylated poly(AA) hydrogels are suitable to 2PP-DLW with a wider processing window than PEGdas. The poly(AA) with the highest degree of acryloylation showed the greatest potential for 3D microfabrication.

  11. Interactions of poly(lactic acid) and poly(lactic acid-co-ethylene oxide) nanoparticles with the plasma factors of the coagulation system.

    PubMed

    Sahli, H; Tapon-Bretaudière, J; Fischer, A M; Sternberg, C; Spenlehauer, G; Verrecchia, T; Labarre, D

    1997-02-01

    When surfactant-stabilized biodegradable poly(lactic acid) (PLA) particles are injected into rats, the rate of clearance from blood is fast. The rate can be strongly reduced by using particles made from diblock copolymers of PLA and poly(ethylene oxide) (PLA-PEO), resulting in an increased duration of contact with the components of the coagulation system. Thus, possible adverse effects such as activation of the coagulation cascade could occur. In this paper, the interactions of surfactant-stabilized PLA and PLA-PEO nanoparticle suspensions with the plasma factors of the coagulation system are presented. PLA suspensions stabilized by sodium cholate (PLA-Ch) interact with thrombin, factor V and calcium ions. Formation of complexes and aggregates is induced by addition of calcium ions to PLA-Ch suspensions in the presence or in the absence of plasma. On the contrary, PLA-PEO suspensions are remarkably inert towards the coagulation factors and calcium ions, even when cholate is present. Steric repulsion owing to the high surface density of PEO is sufficient to avoid strong interations with the proteins and formation of aggregates between particles.

  12. Poly(dopamine) coating of 3D printed poly(lactic acid) scaffolds for bone tissue engineering.

    PubMed

    Kao, Chia-Tze; Lin, Chi-Chang; Chen, Yi-Wen; Yeh, Chia-Hung; Fang, Hsin-Yuan; Shie, Ming-You

    2015-11-01

    3D printing is a versatile technique to generate large quantities of a wide variety of shapes and sizes of polymer. The aim of this study is to develop functionalized 3D printed poly(lactic acid) (PLA) scaffolds and use a mussel-inspired surface coating to regulate cell adhesion, proliferation and differentiation of human adipose-derived stem cells (hADSCs). We prepared PLA 3D scaffolds coated with polydopamine (PDA). The chemical composition and surface properties of PDA/PLA were characterized by XPS. PDA/PLA modulated hADSCs' responses in several ways. Firstly, adhesion and proliferation, and cell cycle of hADSCs cultured on PDA/PLA were significantly enhanced relative to those on PLA. In addition, the collagen I secreted from cells was increased and promoted cell attachment and cell cycle progression were depended on the PDA content. In osteogenesis assay, the ALP activity and osteocalcin of hADSCs cultured on PDA/PLA were significantly higher than seen in those cultured on pure PLA scaffolds. Moreover, hADSCs cultured on PDA/PLA showed up-regulation of the ang-1 and vWF proteins associated with angiogenic differentiation. Our results demonstrate that the bio-inspired coating synthetic PLA polymer can be used as a simple technique to render the surfaces of synthetic scaffolds active, thus enabling them to direct the specific responses of hADSCs.

  13. Osteogenesis of human adipose-derived stem cells on poly(dopamine)-coated electrospun poly(lactic acid) fiber mats.

    PubMed

    Lin, Chi-Chang; Fu, Shu-Juan

    2016-01-01

    Electrospinning is a versatile technique to generate large quantities of micro- or nano-fibers from a wide variety of shapes and sizes of polymer. The aim of this study is to develop functionalized electrospun nano-fibers and use a mussel-inspired surface coating to regulate adhesion, proliferation and differentiation of human adipose-derived stem cells (hADSCs). We prepared poly(lactic acid) (PLA) fibers coated with polydopamine (PDA). The morphology, chemical composition, and surface properties of PDA/PLA were characterized by SEM and XPS. PDA/PLA modulated hADSCs' responses in several ways. Firstly, adhesion and proliferation of hADSCs cultured on PDA/PLA were significantly enhanced relative to those on PLA. Increased focal adhesion kinase (FAK) and collagen I levels and enhanced cell attachment and cell cycle progression were observed upon an increase in PDA content. In addition, the ALP activity and osteocalcin of hADSCs cultured on PDA/PLA were significantly higher than seen in those cultured on a pure PLA mat. Moreover, hADSCs cultured on PDA/PLA showed up-regulation of the ang-1 and vWF proteins associated with angiogenesis differentiation. Our results demonstrate that the bio-inspired coating synthetic degradable PLA polymer can be used as a simple technique to render the surfaces of synthetic biodegradable fibers, thus enabling them to direct the specific responses of hADSCs.

  14. IDENTIFICATION OF DIMETHYLTHIOARSINIC ACID BY ICP-MS AND IC-ESI-MS/MS IN RICE SAMPLES

    EPA Science Inventory

    Recently, sulfur analogs of well known arsenicals have been identified in biological and dietary matrices. In this presentation, the detection and identification of dimethylthioarsinic acid (DMTA) will be reported in rice samples after an enzymatic extraction. The enzymatic ext...

  15. Poly(aspartic acid) (PAA) hydrolases and PAA biodegradation: current knowledge and impact on applications.

    PubMed

    Hiraishi, Tomohiro

    2016-02-01

    Thermally synthesized poly(aspartic acid) (tPAA) is a bio-based, biocompatible, biodegradable, and water-soluble polymer that has a high proportion of β-Asp units and equivalent moles of D- and L-Asp units. Poly(aspartic acid) (PAA) hydrolase-1 and hydrolase-2 are tPAA biodegradation enzymes purified from Gram-negative bacteria. PAA hydrolase-1 selectively cleaves amide bonds between β-Asp units via an endo-type process, whereas PAA hydrolase-2 catalyzes the exo-type hydrolysis of the products of tPAA hydrolysis by PAA hydrolase-1. The novel reactivity of PAA hydrolase-1 makes it a good candidate for a biocatalyst in β-peptide synthesis. This mini-review gives an overview of PAA hydrolases with emphasis on their biochemical and functional properties, in particular, PAA hydrolase-1. Functionally related enzymes, such as poly(R-3-hydroxybutyrate) depolymerases and β-aminopeptidases, are compared to PAA hydrolases. This mini-review also provides findings that offer an insight into the catalytic mechanisms of PAA hydrolase-1 from Pedobacter sp. KP-2.

  16. Culturing primary human osteoblasts on electrospun poly(lactic-co-glycolic acid) and poly(lactic-co-glycolic acid)/nanohydroxyapatite scaffolds for bone tissue engineering.

    PubMed

    Li, Mengmeng; Liu, Wenwen; Sun, Jiashu; Xianyu, Yunlei; Wang, Jidong; Zhang, Wei; Zheng, Wenfu; Huang, Deyong; Di, Shiyu; Long, Yun-Ze; Jiang, Xingyu

    2013-07-10

    In this work, we fabricated polymeric fibrous scaffolds for bone tissue engineering using primary human osteoblasts (HOB) as the model cell. By employing one simple approach, electrospinning, we produced poly(lactic-co-glycolic acid) (PLGA) scaffolds with different topographies including microspheres, beaded fibers, and uniform fibers, as well as the PLGA/nanohydroxyapatite (nano-HA) composite scaffold. The bone-bonding ability of electrospun scaffolds was investigated by using simulated body fluid (SBF) solution, and the nano-HA in PLGA/nano-HA composite scaffold can significantly enhance the formation of the bonelike apatites. Furthermore, we carried out in vitro experiments to test the performance of electrospun scaffolds by utilizing both mouse preosteoblast cell line (MC 3T3 E1) and HOB. Results including cell viability, alkaline phosphatase (ALP) activity, and osteocalcin concentration demonstrated that the PLGA/nano-HA fibers can promote the proliferation of HOB efficiently, indicating that it is a promising scaffold for human bone repair.

  17. Poly(anhydride-ester) and poly(N-vinyl-2-pyrrolidone) blends: salicylic acid-releasing blends with hydrogel-like properties that reduce inflammation.

    PubMed

    Ouimet, Michelle A; Fogaça, Renata; Snyder, Sabrina S; Sathaye, Sameer; Catalani, Luiz H; Pochan, Darrin J; Uhrich, Kathryn E

    2015-03-01

    Polymers such as poly(N-vinyl-2-pyrrolidone) (PVP) have been used to prepare hydrogels for wound dressing applications but are not inherently bioactive. For enhanced healing, PVP was blended with salicylic acid-based poly(anhydride-esters) (SAPAE) and shown to exhibit hydrogel properties upon swelling. In vitro release studies demonstrated that the chemically incorporated drug (SA) was released from the polymer blends over 3-4 d in contrast to 3 h, and that blends of higher PVP content displayed greater swelling values and faster SA release. The polymer blends significantly the inflammatory cytokine, TNF-α, in vitro without negative effects.

  18. Thermoplastic starch/polyester films: effects of extrusion process and poly (lactic acid) addition.

    PubMed

    Shirai, Marianne Ayumi; Olivato, Juliana Bonametti; Garcia, Patrícia Salomão; Müller, Carmen Maria Olivera; Grossmann, Maria Victória Eiras; Yamashita, Fabio

    2013-10-01

    Biodegradable films were produced using the blown extrusion method from blends that contained cassava thermoplastic starch (TPS), poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) with two different extrusion processes. The choice of extrusion process did not have a significant effect on the mechanical properties, water vapor permeability (WVP) or viscoelasticity of the films, but the addition of PLA decreased the elongation, blow-up ratio (BUR) and opacity and increased the elastic modulus, tensile strength and viscoelastic parameters of the films. The films with 20% PLA exhibited a lower WVP due to the hydrophobic nature of this polymer. Morphological analyses revealed the incompatibility between the polymers used.

  19. Synthesis and Properties of pH-, Thermo-, and Salt-Sensitive Modified Poly(aspartic acid)/Poly(vinyl alcohol) IPN Hydrogel and Its Drug Controlled Release

    PubMed Central

    Lu, Jingqiong; Li, Yinhui; Hu, Deng; Chen, Xiaoling; Liu, Yongmei; Wang, Liping; Zhao, Yansheng

    2015-01-01

    Modified poly(aspartic acid)/poly(vinyl alcohol) interpenetrating polymer network (KPAsp/PVA IPN) hydrogel for drug controlled release was synthesized by a simple one-step method in aqueous system using poly(aspartic acid) grafting 3-aminopropyltriethoxysilane (KH-550) and poly(vinyl alcohol) (PVA) as materials. The hydrogel surface morphology and composition were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermal stability was analyzed by thermogravimetric analysis (TGA). The swelling properties and pH, temperature, and salt sensitivities of KPAsp, KPAsp/PVA semi-interpenetrating polymer network (semi-IPN), and KPAsp/PVA IPN hydrogels were also investigated. All of the three hydrogels showed ampholytic pH-responsive properties, and swelling behavior was also extremely sensitive to the temperature, ionic strength, and cationic species. Finally, the drug controlled release properties of the three hydrogels were evaluated and results indicated that three hydrogels could control drug release by external surroundings stimuli. The drug controlled release properties of KPAsp/PVA IPN hydrogel are the most outstanding, and the correlative measured release profiles of salicylic acid at 37°C were 32.6 wt% at pH = 1.2 (simulated gastric fluid) and 62.5 wt% at pH = 7.4 (simulated intestinal fluid), respectively. These results indicated that KPAsp/PVA IPN hydrogels are a promising carrier system for controlled drug delivery. PMID:26351630

  20. Biodegradable Poly (Lactic-co-Glycolic Acid)-Polyethylene Glycol Nanocapsules: An Efficient Carrier for Improved Solubility, Bioavailability, and Anticancer Property of Lutein.

    PubMed

    Arunkumar, Ranganathan; Prashanth, Keelara Veerappa Harish; Manabe, Yuki; Hirata, Takashi; Sugawara, Tatsuya; Dharmesh, Shylaja Mallaiah; Baskaran, Vallikannan

    2015-06-01

    Lutein bioavailability is limited because of its poor aqueous solubility. In this study, lutein-poly (lactic-co-glycolic acid) (PLGA)-polyethylene glycol (PEG) nanocapsules were prepared to improve the solubility, bioavailability, and anticancer property of lutein. The scanning electron microscopy and dynamic light scattering examination revealed that the nanocapsules are smooth and spherical with size ranging from 80 to 500 nm (mean = 200 nm). In vitro lutein release profile from nanocapsules showed controlled sustainable release (66%) up to 72 h. Aqueous solubility of lutein nanocapsules was much higher by 735-fold than the lutein. Fourier transform infrared spectroscopy analyses showed no chemical interaction among PLGA, PEG, and lutein, indicating possible weak intermolecular forces like hydrogen bonds. X-ray diffraction revealed lutein is distributed in a disordered amorphous state in nanocapsules. Postprandial plasma kinetics (area under the curve) of an oral dose of lutein from nanocapsules was higher by 5.4-fold compared with that of micellar lutein (control). The antiproliferative effect of lutein from nanocapsules (IC50 value, 10.9 μM) was higher (43.6%) than the lutein (IC50 value, 25 μM). Results suggest that PLGA-PEG nanocapsule is an efficient carrier for enhancing hydrophilicity, bioavailability, and anticancer property of lipophilic molecules such as lutein.

  1. Polynucleotides XLVII. Synthesis and properties of poly(2-methylthio- and 2-ethylthioadenylic acid). Formation of non-Watson-Crick type complexes.

    PubMed

    Fukui, T; Ikehara, M

    1979-05-24

    Poly(2-methyl- and 2-ethylthioadenylic acid) were prepared by polymerization of corresponding diphosphates with Escherichia coli polynucleotide phosphorylase. These polynucleotides have relatively large hypochromicity of 30-35%. Acid titration of these polymers showed abrupt transition at pH 5.34-5.4, which may indicate that the introduction of alkylthio group at 2-position of adenine bases reduced their basicity. Thermal melting of these polymers showed no clear transition points at neutral pH, but in acidic media they have Tm values of 57 and 56 degrees C, somewhat lower than that of poly(A). Upon complex formation with poly(U), these poly(A) analogs showed only one poly(rs2A) . poly(U) type double-strand complexes, similar to that found in the case of poly(m2A) . poly(U).

  2. Quantitative TOF-SIMS analysis of oligomeric degradation products at the surface of biodegradable poly(alpha-hydroxy acid)s.

    PubMed

    Lee, Joo-Woon; Gardella, Joseph A

    2002-09-01

    This paper reports the development of a new method for quantification of the hydrolytic surface degradation kinetics of biodegradable poly(alpha-hydroxy acid)s using time-of-flight secondary ion mass spectrometry (TOF-SIMS). We report results from static SIMS spectra of a series of poly(alpha-hydroxy acid)s including poly(glycolic acid), poly(L-lactic acid), and random poly(D,L-lactic acid-co-glycolic acid) hydrolyzed in various buffer systems. The distribution of the most intense peak intensities of ions generated in high mass range of the spectrum reflects the intact degradation products (oligomeric hydrolysis products) of each biodegradable polymer. First, a detailed analysis of the oligomeric ions is given based on rearrangement of the intact hydrolysis products. The pattern of ions can distinguish both degradation-generated intact oligomers and their fragment ion peaks with a variety of combinations of each repeat unit. Then, the integration and summation of the area of all ion peaks with the same number of repeat units is proposed as a measurement that provides a more accurate MW average than the typically used method which counts only the most intense peak. The multiple ion summation method described in this paper would be practical in the improvement of quantitative TOF-SIMS studies as a better data reduction method, especially in the surface degradation kinetics of biodegradable polymers.

  3. Radiation synthesis of superabsorbent poly(acrylic acid)-carrageenan hydrogels

    NASA Astrophysics Data System (ADS)

    Francis, Sanju; Kumar, Manmohan; Varshney, Lalit

    2004-04-01

    A series of superabsorbent hydrogels were prepared from carrageenan and partially neutralized acrylic acid by gamma irradiation at room temperature. The gel fraction, swelling kinetics and the equilibrium degree of swelling (EDS) of the hydrogels were studied. It was found that the incorporation of even 1% carrageenan (sodium salt) increases the EDS of the hydrogels from ˜320 to ˜800 g/g. Thermal analysis were carried out to determine the amount of free water and bound water in the hydrogels. Under optimum conditions, poly(acrylic acid)-carrageenan hydrogels with high gel fraction (˜80%) and very high EDS (˜800 g/g) were prepared gamma radiolytically from aqueous solution containing 15% partially neutralized acrylic acid and 1-5% carrageenan. The hydrogels were also found to be sensitive to the pH and the ionic strength of the medium.

  4. Salicylic acid (SA) bioaccessibility from SA-based poly(anhydride-ester).

    PubMed

    Rogers, Michael A; Yan, Yim-Fan; Ben-Elazar, Karen; Lan, Yaqi; Faig, Jonathan; Smith, Kervin; Uhrich, Kathryn E

    2014-09-08

    The bioaccessibility of salicylic acid (SA) can be effectively modified by incorporating the pharmacological compound directly into polymers such as poly(anhydride-esters). After simulated digestion conditions, the bioaccessibility of SA was observed to be statistically different (p < 0.0001) in each sample: 55.5 ± 2.0% for free SA, 31.2 ± 2.4% the SA-diglycolic acid polymer precursor (SADG), and 21.2 ± 3.1% for SADG-P (polymer). The release rates followed a zero-order release rate that was dependent on several factors, including (1) solubilization rate, (2) macroscopic erosion of the powdered polymer, (3) hydrolytic cleavage of the anhydride bonds, and (4) subsequent hydrolysis of the polymer precursor (SADG) to SA and diglycolic acid.

  5. Plasma-induced graft copolymerization of poly(methacrylic acid) on electrospun poly(vinylidene fluoride) nanofiber membrane.

    PubMed

    Kaur, Satinderpal; Ma, Zuwei; Gopal, Renuga; Singh, Gurdev; Ramakrishna, Seeram; Matsuura, Takeshi

    2007-12-18

    Electrospun nanofibrous membranes (ENM) which have a porous structure have a huge potential for various liquid filtration applications. In this paper, we explore the viability of using plasma-induced graft copolymerization to reduce the pore sizes of ENMs. Poly(vinylidene) fluoride (PVDF) was electrospun to produce a nonwoven membrane, comprised of nanofibers with diameters in the range of 200-600 nm. The surface of the ENM was exposed to argon plasma and subsequently graft-copolymerized with methacrylic acid. The effect of plasma exposure time on grafting was studied for both the ENM and a commercial hydrophobic PVDF (HVHP) membrane. The grafting density was quantitatively measured with toluidine blue-O. The degree of grafting increased steeply with an increase in plasma exposure time for the ENM, attaining a maximum of 180 nmol/mg after 120 s of plasma treatment. However, the increase in the grafting density on the surface of the HVHP membrane was not as drastic, reaching a plateau of 65 nmol/mg after 60 s. The liquid entry permeation of water dropped extensively for both membranes, indicating a change in surface properties. Field emission scanning electron microscopy micrographs revealed an alteration in the surface pore structure for both membranes after grafting. Bubble point measurements of the ENM reduced from 3.6 to 0.9 um after grafting. The pore-size distribution obtained using the capillary flow porometer for the grafted ENM revealed that it had a similar profile to that of a commercial hydrophilic commercial PVDF (HVLP) membrane. More significantly, water filtration studies revealed that the grafted ENM had a better flux throughput than the HVLP membrane. This suggests that ENMs can be successfully engineered through surface modification to achieve smaller pores while retaining their high flux performance.

  6. Amphiphilic poly(L-amino acids) - new materials for drug delivery.

    PubMed

    Lalatsa, Aikaterini; Schätzlein, Andreas G; Mazza, Mariarosa; Le, Thi Bich Hang; Uchegbu, Ijeoma F

    2012-07-20

    The formulation of drug compounds into medicines will increasingly rely on the use of specially tailored molecules, which fundamentally alter the drug's pharmacokinetics to enable its therapeutic activity. This is particularly true of the more challenging hydrophobic drugs or therapeutic biological molecules. The demand for such enabled medicines will translate into a demand for advanced highly functionalised drug delivery materials. Polymers have been used to formulate medicines for many decades and this is unlikely to change soon. Amphiphilic polymers based on amino acids are the subject of this review. These molecules, which present as either poly(L-amino acid) block copolymers or poly(L-amino acid) backbones with hydrophobic substituents, self assemble into micelles, vesicles, nanofibres and solid nanoparticles and such self assemblies, have drug delivery capabilities. The nature of the self-assembly depends on the chemistry of the constituent molecules, with the more hydrophilic molecules forming nanosized micellar aggregates including peptide nanofibres, molecules of intermediate hydrophobicity forming polymeric vesicles and the more hydrophobic variants forming amorphous polymeric nanoparticles of 100-1000 nm in diameter. The self-assemblies may be loaded with drugs or may present as micelle forming polymer-drug conjugates and the supramolecular aggregates have been employed as drug solubilisers, tumour targeting agents, gene delivery vectors and facilitators of intracellular drug uptake, with a more promising polymer-drug conjugate progressing to clinical testing.

  7. Tandem mass spectrometry of poly(methacrylic Acid) oligomers produced by negative mode electrospray ionization.

    PubMed

    Giordanengo, Rémi; Viel, Stéphane; Allard-Breton, Béatrice; Thévand, André; Charles, Laurence

    2009-01-01

    Dissociation of small poly(methyl acrylic acid) (PMAA) anions produced by electrospray was characterized by tandem mass spectrometry. Upon collisional activation, singly, and doubly deprotonated PMAA oligomers were shown to fragment via two major reactions, dehydration and decarboxylation. The elimination of a water molecule would occur between two consecutive acid groups in a charged-remote mechanism, giving rise to cyclic anhydrides, and was shown to proceed as many times as pairs of neutral pendant groups were available. As a result, the number of dehydration steps, together with the abundance of the fragment ions produced after the release of all water molecules, revealed the polymerization degree of the molecule in the particular case of doubly charged oligomers. For singly deprotonated molecules, the exact number of MAA units could be reached from the number of carbon dioxide molecules successively eliminated from the fully dehydrated precursor ions. In contrast to dehydration, decarboxylation reactions would proceed via a charge-induced mechanism. The proposed dissociation mechanisms are consistent with results commonly reported in thermal degradation studies of poly(acrylic acid) resins and were supported by accurate mass measurements. These fragmentation rules were successfully applied to characterize a polymeric impurity detected in the tested PMAA sample.

  8. Poly (ADP-ribose) glycohydrolase regulates retinoic acid receptor-mediated gene expression.

    PubMed

    Le May, Nicolas; Iltis, Izarn; Amé, Jean-Christophe; Zhovmer, Alexander; Biard, Denis; Egly, Jean-Marc; Schreiber, Valérie; Coin, Frédéric

    2012-12-14

    Poly-(ADP-ribose) glycohydrolase (PARG) is a catabolic enzyme that cleaves ADP-ribose polymers synthesized by poly-(ADP-ribose) polymerases. Here, transcriptome profiling and differentiation assay revealed a requirement of PARG for retinoic acid receptor (RAR)-mediated transcription. Mechanistically, PARG accumulates early at promoters of RAR-responsive genes upon retinoic acid treatment to promote the formation of an appropriate chromatin environment suitable for transcription. Silencing of PARG or knockout of its enzymatic activity maintains the H3K9me2 mark at the promoter of the RAR-dependent genes, leading to the absence of preinitiation complex formation. In the absence of PARG, we found that the H3K9 demethylase KDM4D/JMJD2D became PARsylated. Mutation of two glutamic acids located in the Jumonji N domain of KDM4D inhibited PARsylation. PARG becomes dispensable for ligand-dependent transcription when either a PARP inhibitor or a non-PARsylable KDM4D/JMJD2D mutant is used. Our results define PARG as a coactivator regulating chromatin remodeling during RA-dependent gene expression.

  9. Preparation and structural characterization of poly-mannose synthesized by phosphoric acid catalyzation under microwave irradiation.

    PubMed

    Wang, Haisong; Cheng, Xiangrong; Shi, Yonghui; Le, Guowei

    2015-05-05

    Poly-mannose with molecular weight of 2.457 kDa was synthesized using d-mannose as substrate and phosphoric acid as catalyst under the condition of microwave irradiation for the first time. The optimum reaction conditions were microwave output power of 900 W, temperature 115°C, proton concentration 2.5 mol/L, and microwave irradiation time 5 min. The actual maximum yield was 91.46%. After purified by Sepherdex G-25 column chromatography, the structural features of poly-mannose were investigated by high-performance anion-exchange chromatography (HPAEC), high-performance gel-permeation chromatography (HPGPC), infrared (IR) spectroscopy, methylation analysis and NMR spectroscopy analysis ((1)H, (13)C, COSY, TOCSY, HMQC, and HMBC). HPAEC analysis showed that the composition of synthetic polysaccharides was d-mannose, its purity was demonstrated by HPGPC as a single symmetrical sharp peak, and additionally IR spectra demonstrated the polymerization of d-mannose. Methylation analysis and NMR spectroscopy revealed that the backbone of poly-mannose consisting of (1→3)-linked β-d-Manp, (1→3)-linked α-d-Manp, and (1→6)-linked α-d-Manp residues, and the main chain were branched at the O-2, O-3, O-4, O-6 position.

  10. Natural and edible biopolymer poly-gamma-glutamic acid: synthesis, production, and applications.

    PubMed

    Sung, Moon-Hee; Park, Chung; Kim, Chul-Joong; Poo, Haryoung; Soda, Kenji; Ashiuchi, Makoto

    2005-01-01

    Poly-gamma-glutamic acid (gamma-PGA) is a very promising biodegradable polymer that is produced by Bacillus subtilis. Gamma-PGA is water-soluble, anionic, biodegradable, and edible. This paper reviews the production of a strain of gamma-PGA and recent developments with respect to applications in terms of Ca absorption, moisturizing properties, gamma-PGA conjugation, super absorbent polymer, and so on. Our recent research shows that gamma-PGA can be used as an immune-stimulating and anti-tumor agent, especially at high molecular weight.

  11. A possible role of poly-3-hydroxybutyric acid in antibiotic production in Streptomyces.

    PubMed

    Verma, Shivani; Bhatia, Yukti; Valappil, Sabeel Padinhara; Roy, Ipsita

    2002-12-01

    The occurrence of poly-3-hydroxybutyric acid (PHB) in 12 different strains of the genus Streptomyces was investigated. Gas chromatographic estimation indicated that all the strains produced PHB and the range of maximum PHB accumulation was between 1.5 and 11.8% dry cell weight. PHB was isolated from Streptomyces coelicolor A3(2) M145 and characterized using Fourier transform-infrared (FT-IR) spectroscopy. The correlation between PHB utilization and antibiotic production in S. coelicolor A3(2) M145, was studied; results indicated a possible role of PHB as a carbon reserve material used for antibiotic production.

  12. Nanosecond T-jump experiment in poly(glutamic acid): a circular dichroism study.

    PubMed

    Mendonça, Lucille; Hache, François

    2012-01-01

    Poly(glutamic acid) has been studied with a nanosecond T-jump experiment. A new experimental set-up based on the frequency-quadrupling of an 82 MHz Titanium-Sapphire laser allows rapid CD measurements to be performed. Combining time-resolved absorption and circular dichroism at 204 and 220 nm, we are able to measure precisely the unfolding relaxation time as well as the helical fraction evolution. We show that only CD at 220 nm is relevant to observe the unfolding of an alpha helix whereas no change is observed for CD at 204 nm. Conversely, both absorptions yield information on the dynamics of the process.

  13. Collagen Stimulators: Poly-L-Lactic Acid and Calcium Hydroxyl Apatite.

    PubMed

    Breithaupt, Andrew; Fitzgerald, Rebecca

    2015-11-01

    Over the last decade, many studies of the structural changes observed in the aging face (in bone, fat pads, facial ligaments, muscle, skin) have increased our understanding that facial rejuvenation is more complex and nuanced than simply filling lines and folds or cutting and lifting soft tissue and skin. This, in addition to the many new products introduced to the marketplace over the same period, has fueled the evolution of panfacial rejuvenation and restoration using fillers. This article discusses current techniques used with calcium hydroxylapatite and poly-l-lactic acid to safely and effectively address changes observed in the aging face.

  14. Stability of electrically induced-polarization in poly (L-lactic) acid for bone regeneration

    NASA Astrophysics Data System (ADS)

    Barroca, Nathalie; Vilarinho, Paula M.; Fernandes, Maria Helena V.; Sharma, Pankaj; Gruverman, Alexei

    2012-07-01

    This paper describes the decay kinetics of electrically induced polarization of poly(L-lactic) acid (PLLA) via piezoresponse force microscopy. Two crystalline forms of PLLA (α and α') were electrically poled at different temperatures (room and above glass transition). Poling at temperatures above glass transition allowed obtaining polarization stable up to 10 days for both forms. This period is enough to trigger and maintain proteins adhesion and cells proliferation, if PLLA is used as a platform for tissue growth. When poled at room temperature, both structures lose polarization after a short time (minutes to hours) being polarization in α PLLA stable for longer time.

  15. n→π* interactions in poly(lactic acid) suggest a role in protein folding.

    PubMed

    Newberry, Robert W; Raines, Ronald T

    2013-09-11

    Poly(lactic acid) (PLA) is a versatile synthetic polyester. We noted that this depsipeptide analog of polyalanine has a helical structure that resembles a polyproline II helix. Using natural bond orbital analysis, we find that n→π* interactions between sequential ester carbonyl groups contribute 0.44 kcal mol(-1) per monomer to the conformational stability of PLA helices. We conclude that analogous n→π* interactions could direct the folding of a polypeptide chain into a polyproline II helix prior to the formation of hydrogen bonds between backbone amides.

  16. Low-velocity impact behavior of woven jute/poly(lactic acid) composites

    NASA Astrophysics Data System (ADS)

    Russo, Pietro; Simeoli, Giorgio; Papa, Ilaria; Acierno, Domenico; Lopresto, Valentina; Langella, Antonio

    2016-05-01

    Biocomposite laminates based on poly(lactic acid) (PLA) and woven jute fabric were obtained by film stacking and compression molding techniques. Sample laminates were systematically characterized by impact tests with a falling dart at impact energies equal to 5, 10 and 20 J. Tests showed that, investigated PLA/jute fabric plates suffer only barely visible damages at the first two levels of impact energy while they result to be perforated at 20 J as highlighted by photographic images taken on low and back side of impacted surfaces.

  17. Adsorption Capability of Cationic Dyes (Methylene Blue and Crystal Violet) onto Poly-γ-glutamic Acid.

    PubMed

    Ogata, Fumihiko; Nagai, Noriaki; Kawasaki, Naohito

    2017-01-01

    In this study, the adsorption capability of cationic dyes, which were methylene blue and crystal violet, by poly-γ-glutamic acid (PGA) in a single or binary solution system was investigated. The effect of the molecular weight of PGA, initial dye concentration, solution pH, and temperature on the adsorption of dyes was evaluated. The adsorption mechanism of dyes onto PGA was the interaction between -COOH group on the PGA surface and the polarity groups of dyes. These results indicated that PGA is useful for removal of dyes and cationic organic compounds from a single or binary solution system.

  18. Biodegradable composites from sugar beet pulp and poly(lactic acid).

    PubMed

    Liu, LinShu; Fishman, Marshall L; Hicks, Kevin B; Liu, Cheng-Kung

    2005-11-16

    Sugar beet pulp and poly(lactic acid) (PLA) composites were prepared by compression-heating. The resultant thermoplastics had a lower density, but they had tensile strength similar to that of pure PLA specimens as well as the same geometric properties. Tensile properties depended on the initial water content of sugar beet pulp and the process by which composites were manufactured. In comparison with sugar beet pulp, the composite showed improved water resistance. This can be attributed to the hydrophobic character of PLA and pulp-matrix interactions. The composite thermoplastics showed suitable properties for potential use as lightweight construction materials.

  19. Spectroscopic characterization of genetically modified flax fibres enhanced with poly-3-hydroxybutyric acid

    NASA Astrophysics Data System (ADS)

    Wróbel-Kwiatkowska, Magdalena; Szopa, Jan; Dymińska, Lucyna; Mączka, Mirosław; Hanuza, Jerzy

    2009-02-01

    Genetically modified flax fibres, derived from transgenic flax with expression of three bacterial genes necessary for synthesis of poly-3-hydroxybutyric acid (PHB), have been analysed. These transgenic flaxes, enhanced with different amount of the PHB, have been studied by FT-IR spectroscopy. The integral intensities of the IR bands have been used for estimation of the chemical content of the normal and transgenic flaxes as well as the differences between the natural and genetically modified flax fibres. The spectroscopic data were compared to those obtained from chemical analysis of flax fibres.

  20. Electrospinning of Polyaniline/Poly(Lactic Acid) Ultrathin Fibers: Process and Statistical Modeling using a Non-Gaussian Approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fibers of poly(lactic acid) (PLA) blended with p-toluenesulfonic acid-doped polyaniline, PAni.TSA, were obtained by lectrospinning, following a factorial design which was used mainly to study the effect of four process parameters (PLA solution concentration, PAni solution concentration, applied volt...

  1. Glycerine and levulinic acid: renewable co-substrates for the fermentative synthesis of short-chain poly(hydroxyalkanoate) biopolymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Glycerine and levulinic acid were used alone and in combination for the fermentative synthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB/V) biopolymers. Shake-flask cultures of Pseudomonas oleovorans NRRL B-14682 containing different glycerine:levulinic acid ratios (1%, w/v total carbon ...

  2. Modified poly(lactic-co-glycolic acid) nanoparticles for enhanced cellular uptake and gene editing in the lung.

    PubMed

    Fields, Rachel J; Quijano, Elias; McNeer, Nicole Ali; Caputo, Christina; Bahal, Raman; Anandalingam, Kavi; Egan, Marie E; Glazer, Peter M; Saltzman, W Mark

    2015-02-18

    Surface-modified poly(lactic-co-glycolic acid) (PLGA)/poly(β-aminoester)(PBAE)nanoparticles (NPs) have shown great promise in gene delivery. In this work, the pulmonary cellular uptake of these NPs is evaluated and surface-modified PLGA/PBAE NPs are shown to achieve higher cellular association and gene editing than traditional NPs composed of PLGA or PLGA/PBAE blends alone.

  3. Dispersion polymerization of styrene using a polystyrene/poly(L-glutamic acid) block copolymer as a stabilizer.

    PubMed

    Itoh, Tomomichi; Komada, Seiji; Ihara, Eiji; Inoue, Kenzo

    2012-12-15

    A block copolymer (PS-b-poly(L-Glu)) composed of polystyrene and poly(l-glutamic acid) was used as a stabilizer for dispersion polymerization of styrene. When dispersion polymerization of styrene was conducted at 70°C in 80% dimethylformamide-water with 0.5 wt% PS-b-poly(L-Glu), spherical polystyrene particles with D(n)=0.72 μm and narrow size distribution were obtained. Whereas AIBN concentration did not have any effects on particle size, molecular weight of the polystyrene particles was strongly dependent on the initiator concentration. As concentration of the PS-b-poly(L-Glu) increased from 0.2 to 1.0 wt%, particle size decreased from D(n)=0.91 to 0.69 μm with keeping surface area occupied by one poly(L-glutamic acid) chain about S=50 nm(2). On the other hand, an increase in initial concentration of styrene from 2 to 20 wt% caused an increase in particle size from D(n)=0.48 to 1.36 μm and a decrease in surface area per poly(L-glutamic acid) block from S=91 to 45 nm(2). Colloidal stability of the polystyrene particles in aqueous solution was responsive to pH due to the surface-grafted poly(L-glutamic acid). For dispersion polymerization of styrene, the PS-b-poly(L-Glu) functions as both a stabilizer and a surface modifier.

  4. Active targeting co-delivery system based on pH-sensitive methoxy-poly(ethylene glycol)2K-poly(ε-caprolactone)4K-poly(glutamic acid)1K for enhanced cancer therapy.

    PubMed

    Li, Nuannuan; Huang, Chunzhi; Luan, Yuxia; Song, Aixin; Song, Yunmei; Garg, Sanjay

    2016-06-15

    In this paper, we successfully synthesized folate-modified pH-sensitive copolymer methoxy-poly(ethylene glycol)2K-poly(ε-caprolactone)4K-poly(glutamic acid)1K (mPEG2K-PCL4K-PGA1K-FA), which could form the polymeric assembly in an aqueous solution, for co-delivering hydrophilic drugs doxorubicin hydrochloride (DOX) and verapamil hydrochloride (VER) (FA-poly(DOX+VER)). Since VER was an effective P-glycoprotein inhibitor, the combination of DOX and VER could reverse the multidrug resistance efficiently and enhance the therapeutic effect. Therefore, the inhibition ratios of MCF-7/ADR resistant cancer cell treated by FA-poly (DOX+VER) were almost more than 30% higher than those of FA-polyDOX after 48h and 72h. Furthermore, the conjugation of FA could lead the co-delivery systems actively targeting into the FA receptor over-expressing cancer cells in addition to the passive accumulation of the assembly in tumor tissues. Importantly, the prepared mPEG2K-PCL4K-PGA1K-FA assembly showed high pH-sensitive property, which made the drugs mostly released in tumor tissue (acid environment) than in physiological environment (neutral environment). In summary, the as-prepared co-delivery system FA-poly(DOX+VER) demonstrated a high efficiency in reversing the multidrug resistance and targeting FA receptor to improve the anticancer effect of DOX in MCF-7/ADR resistant cells.

  5. Entrapment of methyl parathion hydrolase in cross-linked poly(γ-glutamic acid)/gelatin hydrogel.

    PubMed

    Xie, Jianfei; Zhang, Huiwen; Li, Xu; Shi, Yuanliang

    2014-02-10

    Methyl parathion hydrolase (MPH) is an important enzyme in hydrolyzing toxic organophosphorus (OP) compounds. However, MPH is easily deactivated when subjected to extreme environmental conditions and is difficult to recover from the reaction system for reuse, thereby limiting its practical application. To address these shortcomings, we examined the entrapment of MPH in an environment-friendly, biocompatible and biodegradable cross-linked poly(γ-glutamic acid)/gelatin hydrogel. The cross-linked poly(γ-glutamic acid)/gelatin hydrogels were prepared with different gelatin/poly(γ-glutamic acid) mass ratios using water-soluble carbodiimide as the cross-linking agent. The MPH-entrapped cross-linked poly(γ-glutamic acid)/gelatin hydrogel (CPE-MPH) not only possessed improved thermostability, pH stability, and reusability but also exhibited enhanced efficiency in hydrolyzing OP compounds. Furthermore, CPE-MPH possesses high water-absorbing and water-retaining capabilities. We believe that the cross-linked poly(γ-glutamic acid)/gelatin hydrogels are an attractive carrier for the entrapment of diverse enzymes, affording a new approach for enzyme entrapment.

  6. Interfacial Fast Release Layer in Monodisperse Poly (lactic-co-glycolic acid) Microspheres Accelerates the Drug Release.

    PubMed

    Wu, Jun; Zhao, Xiaoli; Yeung, Kelvin W K; To, Michael K T

    2016-01-01

    Understanding microstructural evolutions of drug delivery devices during drug release process is essential for revealing the drug release mechanisms and controlling the drug release profiles. In this study, monodisperse poly (lactic-co-glycolic acid) microspheres in different diameters were fabricated by microfluidics in order to find out the relationships between the microstructural evolutions and the drug release profiles. It was found that poly (lactic-co-glycolic acid) microspheres underwent significant size expansion which took place from the periphery to the center, resulting in the formation of interfacial fast release layers. At the same time, inner pores were created and the diffusion rate was increased so that the early stage drug release was accelerated. Due to the different expansion rates, small poly (lactic-co-glycolic acid) microspheres tendered to follow homogeneous drug release while large poly (lactic-co-glycolic acid) microspheres tendered to follow heterogeneous drug release. This study suggests that the size expansion and the occurrence of interfacial fast release layer were important mechanisms for early stage drug release of poly (lactic-co-glycolic acid) microspheres.

  7. Purification and characterization of gamma poly glutamic acid from newly Bacillus licheniformis NRC20.

    PubMed

    Tork, Sanaa E; Aly, Magda M; Alakilli, Saleha Y; Al-Seeni, Madeha N

    2015-03-01

    γ-poly glutamic acid (γ-PGA) has received considerable attention for pharmaceutical and biomedical applications. γ-PGA from the newly isolate Bacillus licheniformis NRC20 was purified and characterized using diffusion distance agar plate, mass spectrometry and thin layer chromatography. All analysis indicated that γ-PGA is a homopolymer composed of glutamic acid. Its molecular weight was determined to be 1266 kDa. It was composed of L- and D-glutamic acid residues. An amplicon of 3050 represents the γ-PGA-coding genes was obtained, sequenced and submitted in genbank database. Its amino acid sequence showed high similarity with that obtained from B. licheniformis strains. The bacterium NRC 20 was independent of L-glutamic acid but the polymer production enhanced when cultivated in medium containing L-glutamic acid as the sole nitrogen source. Finally we can conclude that γ-PGA production from B. licheniformis NRC20 has many promised applications in medicine, industry and nanotechnology.

  8. Amperometric determination of acetic acid with a trienzyme/poly(dimethylsiloxane)-bilayer-based sensor.

    PubMed

    Mizutani, F; Sawaguchi, T; Sato, Y; Yabuki, S; Lijima, S

    2001-12-01

    A trienzyme sensor for the amperometric determination of acetic acid was prepared by immobilizing acetate kinase (AK), pyruvate kinase (PK), and pyruvate oxidase (PyOx) on a poly(dimethylsiloxane) (PDMS)-coated electrode. AK catalyzes the phospho-transferring reaction between acetic acid and ATP to form ADP; PK, the phospho-transferring reaction between ADP and phosphoenolpyruvate to form pyruvic acid; and PyOx, the oxidation of pyruvic acid with oxygen. The oxygen consumption could be monitored by using the PDMS-coated electrode without interference from the PyOx reaction product, hydrogen peroxide. Thus, the concentration of acetic acid (5 microM-0.5 mM) could be determined from the decrease in the cathodic current at -0.4 V vs Ag/AgCl. This is the first example of a biosensor that can be used for the determination of acetic acid in ethanol-containing food samples. The acetate-sensing electrode could be used for more than one month.

  9. Men and IC

    MedlinePlus

    ... Body-based Practices Energy Medicine Bringing Treatments to Market IC Healthcare Provider Toolkit Join the Provider Registry ... Body-based Practices Energy Medicine Bringing Treatments to Market IC Healthcare Provider Toolkit Join the Provider Registry ...

  10. IC Associated Conditions

    MedlinePlus

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  11. IC Treatment: Surgical Procedures

    MedlinePlus

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  12. IC Treatment: Antihistamines

    MedlinePlus

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  13. General IC Symptoms

    MedlinePlus

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  14. IC: Frequently Asked Questions

    MedlinePlus

    ... Management of IC Pain Complementary Therapies Complementary vs. Alternative Herbs, Dietary Supplements, & Biologicals Mind-body Medicine Massage, Manipulation, & Body-based Practices Energy Medicine Bringing Treatments to Market IC Healthcare Provider ...

  15. Calculation of the hole mobilities of the three homopolynucleotides, poly(guanilic acid), poly(adenilic acid), and polythymidine in the presence of water and Na+ ions.

    PubMed

    Bende, Attila; Bogár, Ferenc; Beleznay, Ferenc; Ladik, János

    2008-12-01

    Recent high resolution x-ray diffraction experiments have determined the structure of nucleosomes. In it 147 base pair long DNA B superhelix is wrapped around the eight nucleohistone proteins. They have found that there are many hydrogen-bonds (H-bonds) between the negative sites phosphate (PO4-) groups DNA, and first of all there is the positively charged lysine and arginine side chains of the histones. This means that there is a non-negligible charge transfer from DNA to the proteins causing a hole current in DNA and an electronic one in the proteins. If the relative positions of the two macromolecules change due to some external disturbances, the DNA moves away from the protein and can be read. If this happens simultaneously at several nucleosomes and at many places in chromatin (built up from the nucleosomes), undesired genetic information becomes readable. This final end can cause the occurrence of oncoproteins at an undesired time point which most probably disturbs the self-regulation of a differentiated cell. The connection of these chain of events with the initiation of cancer is obvious. To look into the details of these events we have used the detailed band structures of the four homopolynucleotides in the presence of water and natrium (Na+) ions calculated previously with the help of the ab initio Hartree-Fock crystal orbital method. We have found that in the case of three homopolynucleotides the width of their valence band is broad enough (approximately 10 times broader than the thermal energy at 300K) for the application of the simple deformation potential approximation for transport calculations. With the help of this we have determined the hole mobilities at 300K and 180K of poly(guanilic acid), poly(adenilic acid), and polythimidine (polycytidine has a too narrow valence band for the application of the deformation potential method). The obtained mobilities are large enough to allow Bloch-type conduction in these systems. At the end of the paper we

  16. Layer-by-layer assembly and characterization of multilayers of a manganese porphyrin linked poly(4-vinylpyridinium) derivative and poly(styrenesulfonic acid-o-maleic) acid.

    PubMed

    Wang, Hong-Lei; Sun, Qing; Chen, Meng; Miyake, Jun; Qian, Dong-Jin

    2011-08-16

    Multilayers of manganese(III) porphyrin-linked poly(vinylpyridinium) (MnTMPyP-PVPMe) polyelectrolyte and poly(styrenesulfonic acid-o-maleic) acid (PSS) have been assembled on gold, quartz, and indium tin oxide surfaces by a layer-by-layer (LBL) technique. The assembly process was monitored by measuring their absorption spectra and frequency change after each assembly, both of which confirmed the formation of three-dimensional MnTMPyP-PVPMe/PSS multilayers. The Soret absorption band of porphyrin red shifted about 8 nm in the multilayer compared with that in the dilute aqueous solution. The average mass changes for each assembly of MnTMPyP-PVPMe and PSS were estimated to be about 2.9 and 0.25 μg/cm(2), respectively. X-ray photoelectron spectra revealed that the as-prepared multilayers were composed of S 2p, C 1s, N 1s, O 1s, and Mn 2p, corresponding to polymers of MnTMPyP-PVPMe and PSS. A rough surface was observed after the assembly of MnTMPyP-PVPMe on the gold surface, but it became smoother when the PSS layer was adsorbed. The significant difference in the mass change and film morphology after the assembly of MnTMPyP-PVPMe compared to those after the assembly of PSS was ascribed to the reason that the MnTMPyP-PVPMe polyelectrolyte contained large metalloporphyrin macrocycles, which were axially coordinated to the pyridyl substituents of the PVP polymeric backbones. The cyclic voltammograms revealed two couples of redox waves in the phosphate electrolyte solution at pH 11, which corresponded to the electron-transfer processes of Mn(II)/Mn(III) and Mn(III)/Mn(IV) of polymeric manganese porphyrin MnTMPyP-PVPMe. The charge-transfer process was also investigated. Finally, the present MnTMPyP-PVPMe/PSS multilayers were used as a heterogeneous catalyst for the decoloration of an azo dye.

  17. Calculation of the hole mobilities of the three homopolynucleotides, poly(guanilic acid), poly(adenilic acid), and polythymidine in the presence of water and Na+ ions

    NASA Astrophysics Data System (ADS)

    Bende, Attila; Bogár, Ferenc; Beleznay, Ferenc; Ladik, János

    2008-12-01

    Recent high resolution x-ray diffraction experiments have determined the structure of nucleosomes. In it 147 base pair long DNA B superhelix is wrapped around the eight nucleohistone proteins. They have found that there are many hydrogen-bonds (H-bonds) between the negative sites phosphate ( PO4- ) groups DNA, and first of all there is the positively charged lysine and arginine side chains of the histones. This means that there is a non-negligible charge transfer from DNA to the proteins causing a hole current in DNA and an electronic one in the proteins. If the relative positions of the two macromolecules change due to some external disturbances, the DNA moves away from the protein and can be read. If this happens simultaneously at several nucleosomes and at many places in chromatin (built up from the nucleosomes), undesired genetic information becomes readable. This final end can cause the occurrence of oncoproteins at an undesired time point which most probably disturbs the self-regulation of a differentiated cell. The connection of these chain of events with the initiation of cancer is obvious. To look into the details of these events we have used the detailed band structures of the four homopolynucleotides in the presence of water and natrium ( Na+ ) ions calculated previously with the help of the ab initio Hartree-Fock crystal orbital method. We have found that in the case of three homopolynucleotides the width of their valence band is broad enough ( ˜10 times broader than the thermal energy at 300K ) for the application of the simple deformation potential approximation for transport calculations. With the help of this we have determined the hole mobilities at 300K and 180K of poly(guanilic acid), poly(adenilic acid), and polythimidine (polycytidine has a too narrow valence band for the application of the deformation potential method). The obtained mobilities are large enough to allow Bloch-type conduction in these systems. At the end of the paper we discuss

  18. Development of poly(aspartic acid-co-malic acid) composites for calcium carbonate and sulphate scale inhibition.

    PubMed

    Mithil Kumar, N; Gupta, Sanjay Kumar; Jagadeesh, Dani; Kanny, K; Bux, F

    2015-01-01

    Polyaspartic acid (PSI) is suitable for the inhibition of inorganic scale deposition. To enhance its scale inhibition efficiency, PSI was modified by reacting aspartic acid with malic acid (MA) using thermal polycondensation polymerization. This reaction resulted in poly(aspartic acid-co-malic acid) (PSI-co-MA) dual polymer. The structural, chemical and thermal properties of the dual polymers were analysed by using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and gel permeation chromatography. The effectiveness of six different molar ratios of PSI-co-MA dual polymer for calcium carbonate and calcium sulphate scale inhibition at laboratory scale batch experiments was evaluated with synthetic brine solution at selected doses of polymer at 65-70°C by the static scale test method. The performance of PSI-co-MA dual polymer for the inhibition of calcium carbonate and calcium sulphate precipitation was compared with that of a PSI single polymer. The PSI-co-MA exhibited excellent ability to control inorganic minerals, with approximately 85.36% calcium carbonate inhibition and 100% calcium sulphate inhibition at a level of 10 mg/L PSI-co-MA, respectively. Therefore, it may be reasonably concluded that PSI-co-MA is a highly effective scale inhibitor for cooling water treatment applications.

  19. Calcium-activated gene transfection from DNA/poly(amic acid-co-imide) complexes.

    PubMed

    Wu, Szu-Yuan; Chang, Li-Ting; Peng, Sydeny; Tsai, Hsieh-Chih

    2015-01-01

    In this study, we synthesized a water-soluble poly(amic acid-co-imide) (PA-I) from ethylenediaminetetraacetic dianhydride (EDTA) and 2,2'-(ethylenedioxy)bis(ethylamine) that possesses comparable transfection efficiency to that of polyethylenimine (PEI), when prepared in combination with divalent calcium cations. The polycondensation of monomers afforded poly(amic acid) (PA) precursors, and subsequent thermal imidization resulted in the formation of PA-I. At a polymer/DNA ratio (indicated by the molar ratio of nitrogen in the polymer to phosphate in DNA) of 40, complete retardation of the DNA band was observed by gel electrophoresis, indicating the strong association of DNA with PA-I. A zeta potential of -22 mV was recorded for the PA-I polymer solution, and no apparent cytotoxicity was observed at concentrations up to 500 μg·mL(-1). In the presence of divalent Ca(2+), the transfection efficiency of PA-I was higher than that of PA, due to the formation of a copolymer/Ca(2+)/DNA polyplex and the reduction in negative charge due to thermal cyclization. Interestingly, a synergistic effect of Ca(2+) and the synthesized copolymer on DNA transfection was observed. The use of Ca(2+) or copolymer alone resulted in unsatisfactory delivery, whereas the formation of three-component polyplexes synergistically increased DNA transfection. Our findings demonstrated that a PA-I/Ca(2+)/DNA polyplex could serve as a promising candidate for gene delivery.

  20. An Investigation of Solid-State Amidization and Imidization Reactions in Vapor Deposited Poly (amic acid)

    SciTech Connect

    Anthamatten, M; Letts, S A; Day, K; Cook, R C; Gies, A P; Hamilton, T P; Nonidez, W K

    2004-06-28

    The condensation polymerization reaction of 4,4'-oxydianiline (ODA) with pyromellitic dianhydride (PMDA) to form poly(amic acid) and the subsequent imidization reaction to form polyimide were investigated for films prepared using vapor deposition polymerization techniques. Fourier-transform infrared spectroscopy (FT-IR), thermal analysis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of films at different temperatures indicate that additional solid-state polymerization occurs prior to imidization reactions. Experiments reveal that, upon vapor deposition, poly(amic acid) oligomers form that have a number-average molecular weight of about 1500 Daltons. Between 100 - 130 C these chains undergo additional condensation reaction to form slightly higher molecular weight oligomers. Calorimetry measurements show that this reaction is exothermic ({Delta}H {approx} -30 J/g) with an activation energy of about 120 kJ/mol. Experimental reaction enthalpies are compared to results from ab initio molecular modeling calculations to estimate the number of amide groups formed. At higher temperatures (150 - 300 C) imidization of amide linkages occurs as an endothermic reaction ({Delta}H {approx} +120 J/g) with an activation energy of about 130 kJ/mol. Solid-state kinetics were found to depend on reaction conversion as well as the processing conditions used to deposit films.

  1. Poly (γ-glutamic acid)/beta-TCP nanocomposites via in situ copolymerization: Preparation and characterization.

    PubMed

    Shu, Xiu-Lin; Shi, Qing-Shan; Feng, Jin; Yang, Yun-Hua; Zhou, Gang; Li, Wen-Ru

    2016-07-01

    A series biodegradable poly (γ-glutamic acid)/beta-tricalcium phosphate (γ-PGA/TCP) nanocomposites were prepared which were composed of poly-γ-glutamic acid polymerized in situ with β-tricalcium phosphate and physiochemically characterized as bone graft substitutes. The particle size via dynamic light scattering, the direct morphological characterization via transmission electron microscopy and field emission scanning electron microscope, which showed that γ-PGA and β-TCP were combined compactly at 80℃, and the γ-PGA/TCP nanocomposites had homogenous and nano-sized grains with narrow particle size distributions. The water uptake and retention abilities, in vitro degradation properties, cytotoxicity in the simulated medium, and protein release of these novel γ-PGA/TCP composites were investigated. Cell proliferation in composites was nearly twice than β-TCP when checked in vitro using MC3T3 cell line. We also envision the potential use of γ-PGA/TCP systems in bone growth factor or orthopedic drug delivery applications in future bone tissue engineering applications. These observations suggest that the γ-PGA/TCP are novel nanocomposites with great potential for application in the field of bone tissue engineering.

  2. Poly(β-L-malic acid) (PMLA) from Aureobasidium spp. and its current proceedings.

    PubMed

    Chi, Zhe; Liu, Guang-Lei; Liu, Chen-Guang; Chi, Zhen-Ming

    2016-05-01

    Poly(β-L-malic acid) is one natural biopolymer that has the outstanding features of biocompatibility, biodegradability, water solubility, and non-immunogenicity, and it is easily chemically modified. So poly(β-L-malic acid) (PMLA) and its derivatives may have a great potential application as a novel drug delivery system and in the production of advanced biomaterials which have attracted so much research attention. The fungi of Aureobasidium spp. have been discovered to be the most suitable candidates for PMLA production in large quantities which satisfy the demand of either research or industry. In this review, we will give an overall summary about the PMLA produced by Aureobasidium spp. based on related research in the last decades and the elaboration of this PMLA producer will also be accomplished. More importantly, the latest proceedings will be specified and some suggestions to the elucidation of a PMLA biosynthesis pathway which remains undefined up to date will be proposed. Finally, through this review, the further exploitation for the application of PMLA from Aureobasidium spp. can be emphasized and promoted.

  3. Poly(acrylic acid) modifying bentonite with in-situ polymerization for removing lead ions.

    PubMed

    He, Y F; Zhang, L; Yan, D Z; Liu, S L; Wang, H; Li, H R; Wang, R M

    2012-01-01

    In this paper, a new kind of poly(acrylic acid) modified clay adsorbent, the poly(acrylic acid)/bentonite composite (PAA/HB) was prepared by in-situ polymerization, and utilized to remove lead(II) ions from solutions. The maximum adsorption of adsorbent is at pH 5 for metal ions, whereas the adsorption starts at pH 2. The effects of contact time (5-60 min), initial concentration of metal ions (200-1,000 mg/L) and adsorbent dosage (0.04-0.12 g/100 mL) have been reported in this article. The experimental data were investigated by means of kinetic and equilibrium adsorption isotherms. The kinetic data were analyzed by the pseudo-first-order and pseudo-second-order equation. The experimental data fitted the pseudo-second-order kinetic model very well. Langmuir and Freundlich isotherms were tried for the system to better understand the adsorption isotherm process. The maximal adsorption capacity of the lead(II) ions on the PAA/HB, as calculated from the Langmuir model, was 769.2 mg/g. The results in this study indicated that PAA/HB was an attractive candidate for removing lead(II) (99%).

  4. Protein absorption and fouling on poly(acrylic acid)-graft-polypropylene microfiltration membrane

    NASA Astrophysics Data System (ADS)

    Liu, Yanjun; Ma, Huiying; Lv, Chunying; Yang, Jia; Fu, Xueqi

    2009-07-01

    A series of pH-sensitive poly (acrylic acid)-graft-polypropylene hollow fiber microfiltration membranes were prepared by UV-photo-irradiation. Bovine serum albumin (BSA) was chosen as the model protein to investigate its absorption and fouling behaviors on membranes. The results showed that the hydrophilicity of grafted membrane was improved by poly(acrylic acid) chains with parts of membrane pores blocked. The grafted membranes were markedly pH-dependent on the water permeability as pH was altered from 1 to 11. The zeta potential of grafted membranes calculated by streaming potential was negative in most pH range. Electrostatic interaction energy calculated by DLVO theory showed the electric interaction force between grafted membrane and BSA was attractive. With the rise of grafting degree, the electric attractive force between grafted membrane and BSA increased as pH=3 and decreased as pH=8, while it kept basically unchanged as pH=4.7. As a result, most serious fouling was observed as pH=4.7. Grafted membranes had a lower BSA absorption and better antifouling behavior as pH=8, while the opposite result was revealed as pH=3. In conclusion, the absorption and fouling behavior of BSA on membranes was pH-dependent due to the pH-dependence of membrane charge, and the conformation of BSA and grafting chains.

  5. An NMR study of structure and dynamics of hydrated poly (aspartic acid) sodium salt

    NASA Astrophysics Data System (ADS)

    Wang, Pixin; Ando, Isao

    1998-06-01

    High-resolution 13C CP/MAS NMR and pulse 1H NMR experiments were carried out for hydrated poly(aspartic acid) sodium salt, in order to investigate the conformation and molecular motion of the polymer. From these experimental results, it is found that the main-chain conformation of poly(aspartic acid) sodium salt which takes an α-helix form in the dry state is not drastically affected by an addition of water. In the 13C CP/MAS NMR spectrum, a new peak at ca. 184 ppm appears, which comes from the formation of hydrogen bond between the carbonyl carbon of the side chains and water, and the intensity of the peak is associated with the water content. The 13C spin-lattice relaxation time ( T1) experiments show that the T1 values for the individual carbons of the polymer are decreased with an increase in the water content. This shows that the mobility of the polymer is increased with an increase in the water content. Further, the 1H spin-spin relaxation time ( T2) experiments show that the polymer has the two or three components with different molecular motion. With an increase in the water content or temperature, the T2 values of hydrated PAANa are increased. This shows that the molecular motion is increased. In the high water content, the polymer has a signal component in the molecular motion. This shows that the polymer is uniformly hydrated.

  6. In vitro characterization of pH-sensitive azithromycin-loaded methoxy poly (ethylene glycol)-block-poly (aspartic acid-graft-imidazole) micelles.

    PubMed

    Teng, Fangfang; Deng, Peizong; Song, Zhimei; Zhou, Feilong; Feng, Runliang; Liu, Na

    2017-02-09

    In order to improve azithromycin's antibacterial activity in acidic medium, monomethoxy poly (ethylene glycol)-block-poly (aspartic acid-graft-imidazole) copolymer was synthesized through allylation, free radical addition, ring-opening polymerization and amidation reactions with methoxy poly (ethylene glycol) as raw material. Drug loading capacity and encapsulation efficiency of azithromycin-loaded micelles prepared via thin film hydration method were 11.58±0.86% and 96.06±1.93%, respectively. The drug-loaded micelles showed pH-dependent property in the respects of particle size, zeta potential at the range of pH 5.5-7.8. It could control drug in vitro release and demonstrate higher release rate at pH 6.0 than that at pH 7.4. In vitro antibacterial experiment indicated that the activity of azithromycin-loaded micelles against S. aureus was superior to free azithromycin in medium at both pH 6.0 and pH 7.4. Using fluorescein as substitute with pH-dependent fluorescence decrease property, laser confocal fluorescence microscopy analysis confirmed that cellular uptake of micelles was improved due to protonation of copolymer's imidazole groups at pH 6.0. The enhanced cellular uptake and release of drug caused its activity enhancement in acidic medium when compared with free drug. The micellar drug delivery system should be potential application in the field of bacterial infection treatment.

  7. Heterogenous expression of poly-gamma-glutamic acid synthetase complex gene of Bacillus licheniformis WBL-3.

    PubMed

    Wang, N; Yang, G; Che, C; Liu, Y

    2011-01-01

    Bacillus licheniformis WBL-3, one of poly-gamma-glutamic acid (gamma-PGA) producers, depends on the existence of glutamate in the medium. In this paper, gamma-PGA synthetase complex gene (pgsBCA) was cloned from Bacillus licheniformis WBL-3. pgsBCA gene of B. licheniformis WBL-3 was highly homologous with pgsBCA gene of B. licheniformis 14580. The similarity was 97%, but the similarity of pgsBCA gene between B. licheniformis WBL-3 and Bacillus subtilis IF03336 was only 74%. However, when pgsBCA was expressed in Escherichia coli, the E. coli clone produced gamma-PGA extracellularly. The yield of gamma-PGA was 8.624 g/l. This result infers that B. licheniformis and B. subtilis has the similar gamma-PGA biosynthesis mechanism, namely, glutamic acid is catalyzed by an ATP-dependent amide ligase to synthesize gamma-PGA.

  8. Novel use of poly(3,4-ethylenedioxythiophene) nanoparticles for fluorescent nucleic acid detection.

    PubMed

    Zhang, Yingwei; Liu, Sen; Wang, Lei; Luo, Yonglan; Tian, Jingqi; Asiri, Abdullah M; Al-Youbi, Abdulrahman O; Sun, Xuping

    2012-03-12

    In this paper, we demonstrate the novel use of poly(3,4-ethylene dioxythiophene) (PEDOT) nanoparticle as a very effective fluorescent sensing platform for the detection of nucleic acid sequences. The principle of the assay lies in the fact that the adsorption of the fluorescently labeled single-stranded DNA (ssDNA) probe by PEDOT nanoparticle leads to substantial fluorescence quenching, followed by specific hybridization with the complementary region of the target DNA sequence. This results in desorption of the hybridized complex from PEDOT nanoparticle surface and subsequent recovery of fluorescence. A detection limit as low as 30 pM could be achieved in this sensing system. We also demonstrate its application for multiplexed detection of nucleic acid sequences. Furthermore, this sensing system can realize the detection of single-base mismatch even in multiplexed format. It is of importance to note that the successful use of this sensing platform in human blood serum system is also demonstrated.

  9. Poly(acrylic acid) nanogel as a substrate for cellulase immobilization for hydrolysis of cellulose.

    PubMed

    Ahmed, Ibrahim Nasser; Chang, Ray; Tsai, Wei-Bor

    2017-04-01

    Cellulase was adsorbed onto poly(acrylic acid), PAA, nanogel, that was fabricated via inverse-phase microemulsion polymerization. The PAA nanogel was around 150nm in diameter and enriched with carboxyl groups. The surface charge of PAA nanogel depended on the pHs of the environment and affected the adsorption of cellulase. The temperature stability of the immobilized cellulase was greatly enhanced in comparison to the free enzyme, especially at high temperature. At 80°C, the immobilized cellulase remained ∼75% of hydrolytic activity, in comparison to ∼55% for the free cellulase. Furthermore, the immobilized cellulase was more active than the free enzyme in acidic buffers. The immobilized cellulase could be recovered via centrifugation and can be used repeatedly, although the recovery ratio needs further improvement. In conclusion, PAA nanogel has the potential in the application of enzyme immobilization for biochemical processes.

  10. Facile fabrication of siloxane @ poly (methylacrylic acid) core-shell microparticles with different functional groups

    NASA Astrophysics Data System (ADS)

    Zhao, Zheng-Bai; Tai, Li; Zhang, Da-Ming; Jiang, Yong

    2017-02-01

    Siloxane @ poly (methylacrylic acid) core-shell microparticles with functional groups were prepared by a facile hydrolysis-condensation method in this work. Three different silane coupling agents 3-methacryloxypropyltrimethoxysilane (MPS), 3-triethoxysilylpropylamine (APTES), and 3-glycidoxypropyltrimethoxysilane (GPTMS) were added along with tetraethoxysilane (TEOS) into the polymethylacrylic acid (PMAA) microparticle ethanol dispersion to form the Si@PMAA core-shell microparticles with different functional groups. The core-shell structure and the surface special functional groups of the resulting microparticles were measured by transmission electron microscopy and FTIR. The sizes of these core-shell microparticles were about 350-400 nm. The corresponding preparation conditions and mechanism were discussed in detail. This hydrolysis-condensation method also could be used to functionalize other microparticles which contain active groups on the surface. Meanwhile, the Si@PMAA core-shell microparticles with carbon-carbon double bonds and amino groups have further been applied to prepare hydrophobic coatings.

  11. Osmium-labeled polynucleotides: reaction of osmium tetraoxide, with poly-1,N6-ethenoadenylic acid.

    PubMed

    Marzilli, L G; Hanson, B E; Kapili, L; Rose, S D; Beer, M

    1978-06-01

    Osmium tetraoxide, in the presence of ligands such as pyridine and bipyridine, adds across the etheno bridge of 1,N6-etheno-9-methyladenine and poly-1,N6-ethenoadenylic acid. The Os:P ratio in the labeled polynucleotide was approximately equal to 1 when bipyridine was used as the stabilizing ligand. A similar study with polycytidylic acid, which had been partially modified with chloroacetaldehyde so that some bases were converted to 3,N4-ethenocytosine, gave an OS:P ratio of approximately equal to 1.3. Calf-thymus DNA, in which the adenine and cytosine bases were modified by chloroacetaldehyde, gave an Os:P ratio of approximately equal to 1 after 24 h. These results suggest that 3,N4-ethenocytosine will add two Os labels.

  12. Investigation on surface structure of potassium permanganate/nitric acid treated poly(tetrafluoroethylene)

    NASA Astrophysics Data System (ADS)

    Fu, Congli; Liu, Shuling; Gong, Tianlong; Gu, Aiqun; Yu, Zili

    2014-10-01

    In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process.

  13. Poly(lactic acid)-Mass production, processing, industrial applications, and end of life.

    PubMed

    Castro-Aguirre, E; Iñiguez-Franco, F; Samsudin, H; Fang, X; Auras, R

    2016-12-15

    Global awareness of material sustainability has increased the demand for bio-based polymers like poly(lactic acid) (PLA), which are seen as a desirable alternative to fossil-based polymers because they have less environmental impact. PLA is an aliphatic polyester, primarily produced by industrial polycondensation of lactic acid and/or ring-opening polymerization of lactide. Melt processing is the main technique used for mass production of PLA products for the medical, textile, plasticulture, and packaging industries. To fulfill additional desirable product properties and extend product use, PLA has been blended with other resins or compounded with different fillers such as fibers, and micro- and nanoparticles. This paper presents a review of the current status of PLA mass production, processing techniques and current applications, and also covers the methods to tailor PLA properties, the main PLA degradation reactions, PLA products' end-of-life scenarios and the environmental footprint of this unique polymer.

  14. In vitro testing of thiolated poly(aspartic acid) from ophthalmic formulation aspects.

    PubMed

    Budai-Szű Cs, Mária; Horvát, Gabriella; Gyarmati, Benjámin; Szilágyi, Barnabás Áron; Szilágyi, András; Csihi, Tímea; Berkó, Szilvia; Szabó-Révész, Piroska; Mori, Michela; Sandri, Giuseppina; Bonferoni, Maria Cristina; Caramella, Carla; Csányi, Erzsébet

    2016-08-01

    Ocular drug delivery formulations must meet anatomical, biopharmaceutical, patient-driven and regulatory requirements. Mucoadhesive polymers can serve as a better alternative to currently available ophthalmic formulations by providing improved bioavailability. If all requirements are addressed, a polymeric formulation resembling the tear film of the eye might be the best solution. The optimum formulation must not have high osmotic activity, should provide appropriate surface tension, pH and refractive index, must be non-toxic and should be transparent and mucoadhesive. We would like to highlight the importance of in vitro polymer testing from a pharmaceutical aspect. We, therefore, carried out physical-chemical investigations to verify the suitability of certain systems for ophthalmic formulations. In this work, in situ gelling, mucoadhesive thiolated poly(aspartic acid)s were tested from ophthalmic formulation aspects. The results of preformulation measurements indicate that these polymers can be used as potential carriers in ophthalmic drug delivery.

  15. ABS polymer electroless plating through a one-step poly(acrylic acid) covalent grafting.

    PubMed

    Garcia, Alexandre; Berthelot, Thomas; Viel, Pascal; Mesnage, Alice; Jégou, Pascale; Nekelson, Fabien; Roussel, Sébastien; Palacin, Serge

    2010-04-01

    A new, efficient, palladium- and chromium-free process for the electroless plating of acrylonitrile-butadiene-styrene (ABS) polymers has been developed. The process is based on the ion-exchange properties of poly(acrylic acid) (PAA) chemically grafted onto ABS via a simple and one-step method that prevents using classical surface conditioning. Hence, ABS electroless plating can be obtained in three steps, namely: (i) the grafting of PAA onto ABS, (ii) the copper Cu(0) seeding of the ABS surface, and (iii) the nickel or copper metallization using commercial-like electroless plating bath. IR, XPS, and SEM were used to characterize each step of the process, and the Cu loading was quantified by atomic absorption spectroscopy. This process successfully compares with the commercial one based on chromic acid etching and palladium-based seed layer, because the final metallic layer showed excellent adhesion with the ABS substrate.

  16. Tacticity control in the synthesis of poly(lactic acid) polymer stars with dipentaerythritol cores.

    PubMed

    Shaver, Michael P; Cameron, Donald J A

    2010-12-13

    The synthesis of a family of polymer stars with arms of varied tacticities is discussed. The effect of polymer tacticity on the physical properties of these polymer stars is presented. Dipentaerythritol cores support six poly(lactic acid) (PLA) arms. Lewis acidic tin and aluminum catalysts control the polymerization to afford polymer stars of variable tacticity. The analysis of these polymers by NMR spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and differential scanning calorimetry reveals the effects of tacticity control on the physical properties of the polymer stars. Preliminary decomposition studies suggest that the biodegradation profile of a polymer star may also be tuned by stereochemical control. This is the first systematic altering of tacticity in PLA polymer stars, showing that polymer tacticity can have a great impact on star properties.

  17. Graft polymerization of acrylic acid and methacrylic acid onto poly(vinylidene fluoride) powder in presence of metallic salt and sulfuric acid

    NASA Astrophysics Data System (ADS)

    Deng, Bo; Yu, Yang; Zhang, Bowu; Yang, Xuanxuan; Li, Linfan; Yu, Ming; Li, Jingye

    2011-02-01

    Poly(vinylidene fluoride) (PVDF) powder was grafted with acrylic acid (AAc) or methacrylic acid (MAA) by the pre-irradiation induced graft polymerization technique. The presence of graft chains was proven by FT-IR spectroscopy. The degree of grafting (DG) was calculated by the acid-base back titration method. The synergistic effect of acid and Mohr's salt on the grafting kinetics was examined. The results indicated that adding sulfuric acid and Mohr's salt simultaneously in AAc or MAA solutions led to a strong enhancement in the degree of grafting. The grafted PVDF powder was cast into microfiltration (MF) membranes using the phase inversion method and some properties of the obtained MF membranes were characterized.

  18. Nucleating effect of exfoliated graphite nanoplatelets on poly(hydroxybutyrate) and poly(lactic acid) and their nanocomposites properties

    NASA Astrophysics Data System (ADS)

    Miloaga, Dana Gabriela

    Multifunctional polymer nanocomposites are attractive due to the multitude of properties that can be imparted to polymer matrices by the addition of small amounts of nanoparticles. Exfoliated graphite nanoplatelets (xGnP) represent a new nanosized reinforcing material that can lead to multifunctional polymer nanocomposites, and are a significantly less expensive alternative to other carbon nanomaterials (e.g. carbon nanotubes). The benefits of xGnP have been shown in nanocomposites made with several petroleum-derived thermoplastic polymers. Nanocomposites from biobased polymers and xGnP have not yet been investigated and are the object of this study. This research is directed at understanding the interactions between xGnP and two polyesters derived from renewable resources, poly(3-hydroxybutyrate) (PHB), and polylactic acid (PLA). PHB and PLA are both semicrystalline polymers. Their properties largely depend on the degree of crystallinity, crystallization rate, and on the size and number of crystallites formed. For faster crystallization, important especially for dynamic processing conditions, both polymers often require the addition of nucleation agents. xGnP is shown to act as a nucleating agent, and to impart higher strength, modulus, thermal and electrical conductivity to these polymer matrices as well. Specifically, the research conducted covers two main aspects of the nucleating effect of xGnP on PHB and PLA: the rate of overall crystallization from the melt as a function of the amount of xGnP, and the influence of xGnP on the morphology and properties of the nanocomposites. A kinetic study of the PHB/xGnP crystallization, employing a modified form of the Avrami equation, revealed that the presence of xGnP increased the PHB crystallization temperature, as well as the crystallization rates. Optical microscopy and atomic force microscopy investigations revealed the reduction in the size of PHB spherulites. Nanocomposite properties were studied for PLA

  19. Complete genome sequence of Bacillus amyloliquefaciens LL3, which exhibits glutamic acid-independent production of poly-γ-glutamic acid.

    PubMed

    Geng, Weitao; Cao, Mingfeng; Song, Cunjiang; Xie, Hui; Liu, Li; Yang, Chao; Feng, Jun; Zhang, Wei; Jin, Yinghong; Du, Yang; Wang, Shufang

    2011-07-01

    Bacillus amyloliquefaciens is one of most prevalent Gram-positive aerobic spore-forming bacteria with the ability to synthesize polysaccharides and polypeptides. Here, we report the complete genome sequence of B. amyloliquefaciens LL3, which was isolated from fermented food and presents the glutamic acid-independent production of poly-γ-glutamic acid.

  20. Novel superhydrophilic poly(l-lactic acid-co-ε-caprolactone)/fibrinogen electrospun patch for rat abdominal wall reconstruction.

    PubMed

    Liu, Zhang; Li, Shaojie; Su, Ling; Sun, Kang; Wu, Xujun; Wu, Feng; Huang, Weihong; Yang, Li; Tang, Jianxiong; He, Hongbing

    2015-08-01

    A novel superhydrophilic hybrid scaffold was created by electrospinning a mixture of poly(l-lactic acid-co-ε-caprolactone) and formulated fibrinogen. The hybrid scaffolds possess the combined benefits of each individual component, such as moderate mechanical strength and excellent biocompatibility. In vitro studies also revealed that endothelial cells seeded on the hybrid scaffolds achieved a relatively high level of cell attachment after three days of culture and a significant increase in the proliferation rate after seven days of culture, compared with pure fibrinogen or poly(l-lactic acid-co-ε-caprolactone) scaffolds. A comparative study of hybrid and pure poly(l-lactic acid-co-ε-caprolactone) patches was performed in an abdominal wall defect model in rats. In both groups, implants degraded by six months, but muscle reconstruction was only observed in the hybrid patch group.

  1. Quantitative analysis of mechanical and electrostatic properties of poly(lactic) acid fibers and poly(lactic) acid-carbon nanotube composites using atomic force microscopy.

    PubMed

    Iqbal, Qais; Bernstein, Peter; Zhu, Yazhe; Rahamim, Joseph; Cebe, Peggy; Staii, Cristian

    2015-03-13

    We use atomic force microscopy (AFM) to perform a systematic quantitative characterization of the elastic modulus and dielectric constant of poly(L-lactic acid) electrospun nanofibers (PLLA), as well as composites of PLLA fibers with 1.0 wt% embedded multiwall carbon nanotubes (MWCNTs-PLLA). The elastic moduli are measured in the fiber skin region via AFM nanoindentation, and the dielectric constants are determined by measuring the phase shifts obtained via electrostatic force microscopy (EFM). We find that the average value for the elastic modulus for PLLA fibers is (9.8 ± 0.9) GPa, which is a factor of 2 larger than the measured average elastic modulus for MWCNT-PLLA composites (4.1 ± 0.7) GPa. We also use EFM to measure dielectric constants for both types of fibers. These measurements show that the dielectric constants of the MWCNT-PLLA fibers are significantly larger than the corresponding values obtained for PLLA fiber. This result is consistent with the higher polarizability of the MWCNT-PLLA composites. The measurement methods presented are general, and can be applied to determine the mechanical and electrical properties of other polymers and polymer nanocomposites.

  2. Introduction of poly[(2-acryloyloxyethyl trimethyl ammonium chloride)-co-(acrylic acid)] branches onto starch for cotton warp sizing.

    PubMed

    Shen, Shiqi; Zhu, Zhifeng; Liu, Fengdan

    2016-03-15

    An attempt has been made to reveal the effect of amphoteric poly(2-acryloyloxyethyl trimethyl ammonium chloride-co-acrylic acid) [P(ATAC-co-AA)] branches grafted onto the backbones of starch upon the adhesion-to-cotton, film properties, and desizability of maize starch for cotton warp sizing. Starch-g-poly[(2-acryloyloxyethyl trimethyl ammonium chloride)-co-(acrylic acid) [S-g-P(ATAC-co-AA)] was prepared by the graft copolymerization of 2-acryloyloxyethyl trimethyl ammonium chloride (ATAC) and acrylic acid (AA) with acid-converted starch (ACS) in aqueous medium using Fe(2+)-H2O2 initiator. The adhesion was evaluated in term of bonding strength according to the FZ/T 15001-2008 whereas the film properties considered included tensile strength, work and percentage elongation at break. The evaluation was undertaken through the comparison of S-g-P(ATAC-co-AA) with ACS, starch-g-poly(acrylic acid), and starch-g-poly(2-acryloyloxyethyl trimethyl ammonium chloride). It was found that the amphoteric branch was able to significantly improve the adhesion and mitigate the brittleness of starch film. Zeta potential of cooked S-g-P(ATAC-co-AA) paste, depending on the mole ratio of ATAC to AA units on P(ATAC-co-AA) branches, had substantial effect on the adhesion and desizability. Increasing the mole ratio raised the potential, which favored the adhesion but disfavored the removal of S-g-P(ATAC-co-AA) from sized cotton warps. Electroneutral S-g-P(ATAC-co-AA) was superior to negatively grafted starch in adhesion and to positively grafted starch in desizability. Generally, it showed better sizing property than ACS, starch-g-poly(acrylic acid), and starch-g-poly(2-acryloyloxyethyl trimethyl ammonium chloride), and had potential in the application of cotton warp sizing.

  3. Polyinosinic:polycytidylic acid loading onto different generations of PAMAM dendrimer-coated magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Khodadust, Rouhollah; Mutlu, Pelin; Yalcın, Serap; Unsoy, Gozde; Gunduz, Ufuk

    2013-08-01

    Poly (I:C), which is a synthetic double-stranded RNA, have significant toxicity on tumor cells. The immobilization of Poly (I:C) onto nanoparticles is important for the fabrication of targeted delivery systems. In this study, different generations of newly synthesized PAMAM dendron-coated magnetic nanoparticles (DcMNP) which can be targeted to the tumor site under magnetic field were efficiently loaded for the first time with Poly (I:C). Different generations of DcMNPs (G2, G3, G4, G5, G6, and G7) were synthesized. Poly (I:C) activation was achieved in the presence of EDC and 1-methylimidazole. Loading of Poly (I:C) onto DcMNPs was followed by agarose gel electrophoresis. Acidic reaction conditions were found as superior to basic and neutral for binding of Poly (I:C). In addition, having more functional groups at the surface, higher generations (G7, G6, and G5) of PAMAM DcMNPs were found more suitable as a delivery system for Poly (I:C). Further in vitro and in vivo analyses of Poly (I:C)/PAMAM magnetic nanoparticles may provide new opportunities for the selective targeting and killing of tumor cells.

  4. Enhanced conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film by acid treatment for indium tin oxide-free organic solar cells

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Chiao; Huang, Chih-Kuo; Hung, Yu-Chieh; Chang, Mei-Ying

    2016-08-01

    An acid treatment is used in the enhancement of the conductivity of the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) thin film, which is often used as the anode in organic solar cells. There are three types of acid treatment for PEDOT:PSS thin film: hydrochloric, sulfuric, and phosphoric acid treatments. In this study, we examine and compare these three ways with each other for differences in conductivity. Hydrochloric acid results in the highest conductivity enhancement, from 0.3 to 1109 S/cm. We also discuss the optical transmittance, conductivity, surface roughness, surface morphology, and stability, as well as the factors that can influence device efficiency. The devices are fabricated using an acid-treated PEDOT:PSS thin film as the anode. The highest power conversion efficiency was 1.32%, which is a large improvement over that of the unmodified organic solar cell (0.21%). It is comparable to that obtained when using indium tin oxide (ITO) as an electrode, ca. 1.46%.

  5. Poly-alpha-glutamic acid synthesis using a novel catalytic activity of RimK from Escherichia coli K-12.

    PubMed

    Kino, Kuniki; Arai, Toshinobu; Arimura, Yasuhiro

    2011-03-01

    Poly-L-α-amino acids have various applications because of their biodegradable properties and biocompatibility. Microorganisms contain several enzymes that catalyze the polymerization of L-amino acids in an ATP-dependent manner, but the products from these reactions contain amide linkages at the side residues of amino acids: e.g., poly-γ-glutamic acid, poly-ε-lysine, and cyanophycin. In this study, we found a novel catalytic activity of RimK, a ribosomal protein S6-modifying enzyme derived from Escherichia coli K-12. This enzyme catalyzed poly-α-glutamic acid synthesis from unprotected L-glutamic acid (Glu) by hydrolyzing ATP to ADP and phosphate. RimK synthesized poly-α-glutamic acid of various lengths; matrix-assisted laser desorption ionization-time of flight-mass spectrometry showed that a 46-mer of Glu (maximum length) was synthesized at pH 9. Interestingly, the lengths of polymers changed with changing pH. RimK also exhibited 86% activity after incubation at 55°C for 15 min, thus showing thermal stability. Furthermore, peptide elongation seemed to be catalyzed at the C terminus in a stepwise manner. Although RimK showed strict substrate specificity toward Glu, it also used, to a small extent, other amino acids as C-terminal substrates and synthesized heteropeptides. In addition, RimK-catalyzed modification of ribosomal protein S6 was confirmed. The number of Glu residues added to the protein varied with pH and was largest at pH 9.5.

  6. Poly-3-hydroxy butyric acid interaction with the transgenic flax fibers: FT-IR and Raman spectra of the composite extracted from a GM flax

    NASA Astrophysics Data System (ADS)

    Wróbel-Kwiatkowska, Magdalena; Żuk, Magdalena; Szopa, Jan; Dymińska, Lucyna; Mączka, Mirosław; Hanuza, Jerzy

    2009-07-01

    The FT-IR and FT-Raman studies have been performed on commercial 3-hydroxy-butyric acid, commercial poly-3-hydroxy butyric acid as well as poly-3-hydroxy butyric acid (PHB) produced by bacteria. The data were compared to those obtained for poly-3-hydroxy butyric acid extracted from natural and genetically modified flax. Genetically modified flax was generated by expression of three bacterial genes coding for synthesis of poly-3-hydroxy butyric acid. Thus transgenic flaxes were enhanced with different amount of the PHB. The discussion of polymer structure and vibrational properties has been done in order to get insight into differences among these materials. The interaction between the cellulose of flax fibers and embedded poly-3-hydroxybutyric acid has been also discussed. The spectroscopic data provide evidences for structural changes in cellulose and in PHB when synthesized in fibers. Based on this data it is suggesting that cellulose and PHB interact by hydrogen and ester bonds.

  7. Protein adsorption, fibroblast activity and antibacterial properties of poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) grafted with chitosan and chitooligosaccharide after immobilized with hyaluronic acid.

    PubMed

    Hu, S-G; Jou, C-H; Yang, M C

    2003-07-01

    Poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) membrane was treated with ozone and grafted with acrylic acid. The resulting membranes were further grafted with chitosan (CS) or chitooligosaccharide (COS) via esterification. Afterward hyaluronic acid (HA) was immobilized onto CS- or COS-grafting membranes. The antibacterial activity of CS and COS against Staphylococus aureus, Escherichia coli, and Pseudomonas aeruginosa was preserved after HA immobilization. Among them, CS-grafted PHBV membrane showed higher antibacterial activity than COS-grafted PHBV membrane. In addition, after CS- or COS-grafting, the L929 fibroblasts attachment and protein adsorption were improved, while the cell number was decrease. After immobilizing HA, the cell proliferation was promoted, the protein adsorption was decreased, and the cell attachment was slightly lower than CS- or COS-grafting PHBV.

  8. Enhanced Production of Poly-γ-glutamic Acid by Bacillus licheniformis TISTR 1010 with Environmental Controls.

    PubMed

    Kongklom, Nuttawut; Shi, Zhongping; Chisti, Yusuf; Sirisansaneeyakul, Sarote

    2016-12-24

    Bacillus licheniformis TISTR 1010 was used for glutamic acid-independent production of poly-γ-glutamic acid (γ-PGA). A fed-batch production strategy was developed involving feedings of glucose, citric acid, and ammonium chloride at specified stages of the fermentation. With the dissolved oxygen concentration controlled at ≥50% of air saturation and the pH controlled at ~7.4, the fed-batch operation at 37 °C afforded a peak γ-PGA concentration of 39.9 ± 0.3 g L(-1) with a productivity of 0.926 ± 0.006 g L(-1) h(-1). The observed productivity was nearly threefold greater than previously reported for glutamic acid-independent production using the strain TISTR 1010. The molecular weight of γ-PGA was in the approximate range of 60 to 135 kDa.

  9. Poly(N-vinylimidazole) gels as insoluble buffers that neutralize acid solutions without dissolving.

    PubMed

    Horta, Arturo; Piérola, Inés F

    2009-04-02

    Typical buffers are solutions containing weak acids or bases. If these groups were anchored to insoluble gels, what would be their behavior? Simple thermodynamics is used to calculate the pH in two-phase systems that contain the weak acid or base fixed to only one of the phases and is absent in the other. The experimental reference of such systems are pH sensitive hydrogels and heterogeneous systems of biological interest. It is predicted that a basic hydrogel immersed in slightly acidic solutions should absorb the acid and leave the external solution exactly neutral (pH 7). This is in accordance with experimental results of cross-linked poly(N-vinylimidazole). The pH 7 cannot be obtained if the system were homogeneous; the confinement of the weak base inside the gel phase is a requisite for this neutral pH in the external solution. The solution inside the gel is regulated to a much higher pH, which has important implications in studies on chemical reactions and physical processes taking place inside a phase insoluble but in contact with a solution.

  10. Cisplatin-incorporated nanoparticles of poly(acrylic acid-co-methyl methacrylate) copolymer

    PubMed Central

    Lee, Kyung Dong; Jeong, Young-Il; Kim, Da Hye; Lim, Gyun-Taek; Choi, Ki-Choon

    2013-01-01

    Background Although cisplatin is extensively used in the clinical field, its intrinsic toxicity limits its clinical use. We investigated nanoparticle formations of poly(acrylic acid-co-methyl methacrylate) (PAA-MMA) incorporating cisplatin and their antitumor activity in vitro and in vivo. Methods Cisplatin-incorporated nanoparticles were prepared through the ion-complex formation between acrylic acid and cisplatin. The anticancer activity of cisplatin-incorporated nanoparticles was assessed with CT26 colorectal carcinoma cells. Results Cisplatin-incorporated nanoparticles have small particle sizes of less than 200 nm with spherical shapes. Drug content was increased according to the increase of the feeding amount of cisplatin and acrylic acid content in the copolymer. The higher acrylic acid content in the copolymer induced increase of particle size and decrease of zeta potential. Cisplatin-incorporated nanoparticles showed a similar growth-inhibitory effect against CT26 tumor cells in vitro. However, cisplatin-incorporated nanoparticles showed improved antitumor activity against an animal tumor xenograft model. Conclusion We suggest that PAA-MMA nanoparticles incorporating cisplatin are promising carriers for an antitumor drug-delivery system. PMID:23966778

  11. Technological and economic potential of poly(lactic acid) and lactic acid derivatives

    SciTech Connect

    Datta, R.; Tsai, S.P.; Bonsignore, P.; Moon, S.H.; Frank, J.R.

    1993-10-01

    Lactic acid has been an intermediate-volume specialty chemical (world production {approximately}40,000 tons/yr) used in a wide range of food processing and industrial applications. lactic acid h,as the potential of becoming a very large volume, commodity-chemical intermediate produced from renewable carbohydrates for use as feedstocks for biodegradable polymers, oxygenated chemicals, plant growth regulators, environmentally friendly ``green`` solvents, and specially chemical intermediates. In the past, efficient and economical technologies for the recovery and purification of lactic acid from crude fermentation broths and the conversion of tactic acid to the chemical or polymer intermediates had been the key technology impediments and main process cost centers. The development and deployment of novel separations technologies, such as electrodialysis (ED) with bipolar membranes, extractive distillations integrated with fermentation, and chemical conversion, can enable low-cost production with continuous processes in large-scale operations. The use of bipolar ED can virtually eliminate the salt or gypsum waste produced in the current lactic acid processes. In this paper, the recent technical advances in tactic and polylactic acid processes are discussed. The economic potential and manufacturing cost estimates of several products and process options are presented. The technical accomplishments at Argonne National Laboratory (ANL) and the future directions of this program at ANL are discussed.

  12. Poly(brilliant green) and poly(thionine) modified carbon nanotube coated carbon film electrodes for glucose and uric acid biosensors.

    PubMed

    Ghica, M Emilia; Brett, Christopher M A

    2014-12-01

    Poly(brilliant green) (PBG) and poly(thionine) (PTH) films have been formed on carbon film electrodes (CFEs) modified with carbon nanotubes (CNT) by electropolymerisation using potential cycling. Voltammetric and electrochemical impedance characterisation were performed. Glucose oxidase and uricase, as model enzymes, were immobilised on top of PBG/CNT/CFE and PTH/CNT/CFE for glucose and uric acid (UA) biosensing. Amperometric determination of glucose and UA was carried out in phosphate buffer pH 7.0 at -0.20 and +0.30 V vs. SCE, respectively, and the results were compared with other similarly modified electrodes existing in the literature. An interference study and recovery measurements in natural samples were successfully performed, indicating these architectures to be good and promising biosensor platforms.

  13. pH-sensing properties of cascaded long- and short-period fiber grating with poly acrylic acid/poly allylamine hydrochloride thin-film overlays

    NASA Astrophysics Data System (ADS)

    Yang, Ying

    2014-11-01

    Based on coupled-mode theory and transfer matrix method, the mode coupling mechanism and the reflection spectral properties of coated cascaded long- and short-period gratings (CLBG) are discussed. The effects of the thin-film parameters (film refractive index and film thickness) on the reflection spectra of the coated CLBG are simulated. By using electrostatic self-assembly method, poly acrylic acid (PAA) and poly allylamine hydrochloride (PAH) multilayer molecular pH-sensitive thin-films are assembled on the surface of the partial corroded CLBG. When the CLBG coated with PAA/PAH films are used to sense pH values, the resonant wavelengths of the CLBG have almost no shift, whereas the resonance peak reflectivities change with pH values. In addition, the sensitivities of the resonance peak reflectivities responding to pH values are improved by an order of magnitude.

  14. Self-assembling linear and star shaped poly(ϵ-caprolactone)/poly[(meth)acrylic acid] block copolymers as carriers of indomethacin and quercetin.

    PubMed

    Bury, Katarzyna; Du Prez, Filip; Neugebauer, Dorota

    2013-11-01

    A amphiphilic linear AB, BAB, and star shaped (AB)3 block copolymers of poly(ϵ-caprolactone) (PCL)/poly(meth)acrylic acid (P(M)AA) are used for the preparation of nanoparticles and drug entrapment, where indomethacin and quercetin are employed as model drugs. Drug loading experiments with the nanoparticles based on PAA block copolymers demonstrate a higher efficiency for the star structure, whereas the PMAA star copolymer presents the lowest entrapment ability. The release properties are studied at room temperature and 37 °C in phosphate buffer solutions with pH equal to 5 and 7.4. The kinetic profiles show a strong relation to the copolymer's topology, indicating the lowest release rates from the star based superstructures, while the PMAA particles are less stable than those containing PAA segment(s).

  15. A study of structure and dynamics of poly(aspartic acid) sodium/poly(vinyl alcohol) blends by 13C CP/MAS NMR

    NASA Astrophysics Data System (ADS)

    Wang, P.; Ando, I.

    1999-09-01

    Solid state 13C CP/MAS NMR measurements have been carried out on poly(aspartic acid) sodium (PAANa)/poly(vinyl alcohol) (PVA) blends over a wide range of temperatures. From these experimental results, it is found that the main-chain conformations of PAANa in PAANa/PVA blends take the α-helix form over a wide range of blend ratios, and, in contrast, the conformation and dynamics of the side chains of PAANa are strongly influenced by the formation of an intermolecular hydrogen bond between the carboxyl group of the side chains and the hydroxyl group of PVA. The behavior of the proton spin-lattice relaxation times in the rotating frame ( T1 ρ(H)) and the laboratory frame ( T1(H)) indicates that when the blend ratio of PAANa and PVA is 1:1, they are miscible.

  16. Organosoluble enzyme conjugates with poly(2-oxazoline)s via pyromellitic acid dianhydride.

    PubMed

    Konieczny, Stefan; Fik, Christoph P; Averesch, Nils J H; Tiller, Joerg C

    2012-06-15

    The use of enzymes in organic solvents offers a great opportunity for the synthesis of complex organic compounds and is therefore in focus of current research. In this work we describe the synthesis of poly(2-methyl-1,3-oxazoline) (PMOx) and poly(2-ethyl-1,3-oxazoline) (PEtOx) enzyme conjugates with hen-egg white lysozyme, RNase A and α-chymotrypsin using a new coupling technique. The POXylation was carried out reacting pyromellitic acid dianhydride subsequently with ethylenediamine terminated POx and then with the NH₂-groups of the respective enzymes. Upon conjugation with the polymers, RNase A and lysozyme became fully soluble in DMF (1.4 mg/ml). These are the first examples of fully POXylated proteins, which become organosoluble. The synthesized enzyme conjugates were characterized by SDS-PAGE, isoelectric focusing, dynamic light scattering and size exclusion chromatography, which all indicated the full POXylation of the enzymes. The modified enzymes even partly retained their activity in water. With α-chymotrypsin as example we could demonstrate that the molecular weight of the attached polymer significantly influences the activity.

  17. Surface characterization of poly(L-lactic acid)-methoxy poly(ethylene glycol) diblock copolymers by static and dynamic contact angle measurements, FTIR, and ATR-FTIR.

    PubMed

    Mert, O; Doganci, E; Erbil, H Y; Demir, A S

    2008-02-05

    The surface composition and surface free energy properties of two types of amphiphilic and semicrystalline diblock copolymers consisting of poly(L-lactic acid) coupled to (methoxy poly(ethylene glycol) (PLLA-MePEG) having differing block lengths of PEG were investigated by using static and dynamic contact angle measurements, transmission Fourier infrared spectroscopy (FTIR), and attenuated total reflection spectroscopy (ATR-FTIR) and compared with results obtained from PLLA and MePEG homopolymers. The contact angle results were evaluated by using the van Oss-Good method (acid-base method), and it was determined that the Lewis base surface tension coefficient (gamma-) of the copolymers increased with an increase of the PEG molar content at the copolymer surface. This result is in good agreement with the transmission FTIR and ATR-FTIR results but not proportional to them, indicating that the surfaces of the copolymers are highly mobile and that the molecular rearrangement takes place upon contact with a polar liquid drop. The dynamic contact angle measurements showed that the strong acid-base interaction between the oxygen atoms in the copolymer backbone of the relatively more hydrophilic PEG segments with the Lewis acidic groups of the polar and hydrogen-bonding water molecules enabled the surface molecules to restructure (conformational change) at the contact area, so that the PEG segments moved upward, whereas the apolar methyl pendant groups of PLLA segments buried downward.

  18. Poly(lactic acid) nanoparticles loaded with ursolic acid: Characterization and in vitro evaluation of radical scavenging activity and cytotoxicity.

    PubMed

    Antônio, Emilli; Antunes, Osmar Dos Reis; de Araújo, Isis Souza; Khalil, Najeh Maissar; Mainardes, Rubiana Mara

    2017-02-01

    The purpose of this study was to develop poly(lactic acid) (PLA) nanoparticles containing ursolic acid (UA) by an emulsification-solvent evaporation technique and evaluate the radical scavenging activity over hypochlorous acid (HOCl) and cytotoxicity over erythrocytes and tumor cells. Nanoparticles were successfully obtained and presented mean size of 246nm with spherical or slightly oval morphology, negative zeta potential and 96% of UA encapsulation efficiency. Analyses of FTIR, XRD and DSC-DTG suggest interaction/complexation of UA with PLA matrix and drug amorphization promoted by nanoencapsulation process. Stability study showed that room temperature was the best condition for nanoparticles storage. The in vitro release study showed UA was released from the polymeric matrix over two constants (α, β), suggesting a second order kinetics. After 120h of assay, 60% of UA were released by diffusion. In the HOCl scavenging activity, after 72h of assay UA-loaded nanoparticles presented the same efficacy of free drug. In cytotoxicity test over red blood cells, UA-loaded nanoparticles showed less toxicity on cells than free drug. The cytotoxicity assay over melanoma cells line (B16-F10) showed after 72h that nanoparticles were able to reduce the cell viability in 70%. PLA nanoparticles showed be potential carriers for UA maintaining the antioxidant and antitumor activity of the UA and decreasing its cytotoxicity over normal cells.

  19. Crystallization kinetics of poly-(lactic acid) with and without talc: Optical microscopy and calorimetric analysis

    NASA Astrophysics Data System (ADS)

    Refaa, Z.; Boutaous, M.; Rousset, F.; Fulchiron, R.; Zinet, M.; Xin, S.; Bourgin, P.

    2014-05-01

    Poly-(lactic acid) or PLA is a biodegradable polymer synthesized from renewable resources. Recently, the discovery of new polymerization routes has allowed increasing the produced volumes. As a consequence, PLA is becoming of great interest for reducing the dependence on petroleum-based plastics. Because of its interesting mechanical properties, PLA is seen as a potential substitute for some usual polymers. However, its relatively slow crystallization kinetics can be a disadvantage with regard to industrial applications. The crystallization kinetics of PLA can be enhanced by adding nucleating agents, which also influences on crystalline morphology and rheological behavior. In the present work, the isothermal quiescent crystallization kinetics of both neat PLA and PLA/talc composite (5 wt% talc) are investigated. The effects of talc on the overall crystallization kinetics and on the crystalline morphology are analyzed using both optical microscopy measurements and thermal analysis by differential scanning calorimetry.

  20. Holographic gratings recorded in poly(lactic acid)/azo-dye films

    NASA Astrophysics Data System (ADS)

    Cambiasso, Javier; Goyanes, Silvia; Ledesma, Silvia

    2015-09-01

    Diffraction gratings were recorded in biodegradable polymer films of poly(lactic acid) doped with the photoisomerisable azo-dye (Disperse Orange 3). It is shown that the diffraction efficiency of the recorded grating can be improved by 220% via an all-optical treatment. This all-optical treatment consists of a pre-irradiation of the sample with the writing laser beam at high power during a short period of time, preventing damage of the material, followed by a much longer inscription at relatively low power. Furthermore, it is shown that the addition of a small amount of 0.05 wt% of multi-walled carbon nanotubes to the photoresponsive polymer increases the maximum diffraction efficiency as well as the remanent efficiency by 20%. Finally, this last photoresponsive nano-composite is also sensitive to the pre-irradiation treatment.

  1. Synthesis and characterization of zinc chloride containing poly(acrylic acid) hydrogel by gamma irradiation

    NASA Astrophysics Data System (ADS)

    Park, Jong-Seok; Kuang, Jia; Gwon, Hui-Jeong; Lim, Youn-Mook; Jeong, Sung-In; Shin, Young-Min; Seob Khil, Myung; Nho, Young-Chang

    2013-07-01

    In this study, the characterization of zinc chloride incorporated into a poly(acrylic acid) (PAAc) hydrogel prepared by gamma-ray irradiation was investigated. Zinc chloride powder with different concentrations was dissolved in the PAAc solution, and it was crosslinked with gamma-ray irradiation. The effects of various parameters such as zinc ion concentration and irradiation doses on characteristics of the hydrogel formed were investigated in detail for obtaining an antibacterial wound dressing. In addition, the gel content, pH-sensitive (pH 4 or 7) swelling ratio, and UV-vis absorption spectra of the zinc particles in the hydrogels were characterized. Moreover, antibacterial properties of these new materials against Staphylococcus aureus and Escherichia coli strains were observed on solid growth media. The antibacterial tests indicated that the zinc chloride containing PAAc hydrogels have good antibacterial activity.

  2. Structure and properties of poly (lactic acid)/Sterculia urens uniaxial fabric biocomposites.

    PubMed

    Jayaramudu, J; Reddy, G Siva Mohan; Varaprasad, K; Sadiku, E R; Ray, S Sinha; Rajulu, A Varada

    2013-05-15

    Uniaxial cellulose fabric Sterculia urens reinforced poly (lactic acid) (PLA) matrix biocomposites were prepared by a two-roll mill. In order to assess the suitability of Sterculia fabric as reinforcement for PLA matrix, the PLA/Sterculia fabric biocomposites were prepared. Tensile parameters, such as maximum stress, Young's modulus and elongation-at-break, were determined using the Universal Testing Machine. The effect of alkali treatment and silane-coupling agent on the tensile properties of PLA-based biocomposites was studied. The results of thermogravimetric analysis show that uniaxial treatment of the fabric can improve the degradation temperature of the biocomposites. Moreover, morphological studies by scanning electron microscopy confirmed that better adhesion between the uniaxial fabric and the matrix was achieved. It was established that standard PLA resins are suitable for the manufacture of S. urens uniaxial fabric reinforced biocomposites with excellent engineering properties, useful for food packaging.

  3. Impact property enhancement of poly (lactic acid) with different flexible copolymers

    NASA Astrophysics Data System (ADS)

    Likittanaprasong, N.; Seadan, M.; Suttiruengwong, S.

    2015-07-01

    The objective of this work was to improve the impact property of Poly (lactic acid) (PLA) by blending with different copolymers. Six flexible copolymers, namely, acrylonitrile butadiene styrene (ABS) powder, Biomax, polybutyrate adipate co-terephthalate (PBAT), polyether block amide (PEBAX), ethylene-vinyl acetate (EVA) and ethylene acrylic elastomer (EAE), with loading less than 20wt% were used and compared. The rheological, mechanical and morphological properties of samples were investigated by melt flow index, tensile testing, impact testing and scanning electron microscope (SEM), respectively. It was found that PLA added 20wt% EAE showed the highest impact strength (59.5 kJ/m2), which was 22 times higher than neat PLA. The elongation at break was also increased by 12 folds compared to neat PLA. The SEM images showed good interface and distribution for PLA containing 20wt% EAE, 15 phr Biomax and 20 wt% PEBAX.

  4. Poly (acrylic acid)-capped lanthanide-doped BaFCl nanocrystals: synthesis and optical properties.

    PubMed

    Ju, Qiang; Luo, Wenqin; Liu, Yongsheng; Zhu, Haomiao; Li, Renfu; Chen, Xueyuan

    2010-07-01

    Water-soluble lanthanide-doped BaFCl nanophosphors with the surface functionalized by a layer of poly (acrylic acid) are synthesized via a facile one-step solvothermal method. Intense long-lived luminescence is realized from visible to near-infrared (NIR) by doping with different lanthanide ions. The emission and excitation spectra of Eu(3+) indicate that the doped lanthanide ions occupy a site close to the surface of the nanoparticles. Strong NIR emissions of Nd(3+) and green luminescence of Tb(3+) using Ce(3+) as sensitizers are also achieved in BaFCl nanoparticles. The synthesized nanoparticles featuring long-lived luminescence in either visible or NIR regions may have potential applications as luminescent labels for biological applications.

  5. 3D Printing Biocompatible Polyurethane/Poly(lactic acid)/Graphene Oxide Nanocomposites: Anisotropic Properties.

    PubMed

    Chen, Qiyi; Mangadlao, Joey Dacula; Wallat, Jaqueline; De Leon, Al; Pokorski, Jonathan K; Advincula, Rigoberto C

    2017-02-01

    Blending thermoplastic polyurethane (TPU) with poly(lactic acid) (PLA) is a proven method to achieve a much more mechanically robust material, whereas the addition of graphene oxide (GO) is increasingly applied in polymer nanocomposites to tailor further their properties. On the other hand, additive manufacturing has high flexibility of structure design which can significantly expand the application of materials in many fields. This study demonstrates the fused deposition modeling (FDM) 3D printing of TPU/PLA/GO nanocomposites and its potential application as biocompatible materials. Nanocomposites are prepared by solvent-based mixing process and extruded into filaments for FDM printing. The addition of GO largely enhanced the mechanical property and thermal stability of the nanocomposites. Interestingly, we found that the mechanical response is highly dependent on printing orientation. Furthermore, the 3D printed nanocomposites exhibit good biocompatibility with NIH3T3 cells, indicating promise as biomaterials scaffold for tissue engineering applications.

  6. Electrochemical performance of electroactive poly(amic acid)-Cu2+ composites

    NASA Astrophysics Data System (ADS)

    Yan, Ying; Li, Fangfei; Hanlon, Ashley M.; Berda, Erik B.; Liu, Xincai; Wang, Ce; Chao, Danming

    2017-01-01

    Electroactive poly(amic acid)-Cu2+ (EPAA-Cu) composites on substrates were successfully prepared via nucleophilic polycondensation followed by the use of an immersing method. Analysis of the structure properties of EPAA-Cu composites was performed using scanning electron microscopy (SEM), X-ray photoelectron spectra (XPS) and Fourier-transform infrared spectra (FTIR). A significant current enhancement phenomenon of EPAA-Cu/ITO electrodes was found as evident from cyclic voltammetry (CV) measurements. In addition, Cu2+ ions were incorporated into the composites and had a positive effect on their electrochromic behaviors decreasing their switching times. The anticorrosive performance of EPAA-Cu composites coatings on the carbon steel in 3.5 wt% NaCl solution were also investigated in detail using tafel plots analysis and electrochemical impedance spectroscopy. The anticorrosive ability of these coatings significantly enhanced through the incorporation of Cu2+ ions.

  7. Adsorption of poly acrylic acid onto the surface of calcite: an experimental and simulation study.

    PubMed

    Sparks, David J; Romero-González, Maria E; El-Taboni, Elfateh; Freeman, Colin L; Hall, Shaun A; Kakonyi, Gabriella; Swanson, Linda; Banwart, Steven A; Harding, John H

    2015-11-07

    Macromolecular binding to minerals is of great importance in the formation of biofilms, and carboxylate functional groups have been found to play a pivotal role in the functioning of these macromolecules. Here we present both fluorescence time-resolved anisotropy measurements and simulation data on the conformational behaviour and binding of a poly acrylic acid polymer. In solution the polymer exhibits a pH dependent behaviour, with a coiled conformation at a low pH and extended conformation at higher pH values. The polymer is readily adsorbed on the surface of calcite, preferring to bind in an extended conformation, with the strength of the adsorption dependent on the pH and presence of counter ions. We discuss the reasons why the calculated adsorption free energy differs from that obtained from a Langmuir isotherm analysis, showing that they refer to different quantities. The enhanced binding of the extended conformations shows the importance of flexibility in the binding of macromolecules.

  8. Novel solid-phase synthesis of thiol-terminated-poly(alpha-amino acid)-drug conjugate.

    PubMed

    Palacios, P; Bussat, P; Bichon, D

    1991-01-01

    A new method using a controlled pore glass solid support for the preparation of a thiol-terminated-polymerdrug, notably poly-L-glutamate-daunomycin having a terminal thiol group, is described. The method consists of first polymerizing an ester-protected glutamic acid onto an amino-disulfide functionalized controlled pore glass support. The ester protecting group is then removed, freeing the gamma-carboxyl groups of the grafted polymer which then allows it to react with daunomycin. Finally, the disulfide bond linking the conjugated polymer-drug to the solid support is broken by thiolysis, thus releasing the desired product. The final product consists of only polymer-drug conjugates with terminal thiol groups (global yield 26%). This novel method is much simpler and more elegant than more conventional preparation methods requiring solution phase techniques.

  9. Biodegradability of poly(lactic-co-glycolic acid) after femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Shibata, Akimichi; Yada, Shuhei; Terakawa, Mitsuhiro

    2016-06-01

    Biodegradation is a key property for biodegradable polymer-based tissue scaffolds because it can provide suitable space for cell growth as well as tailored sustainability depending on their role. Ultrashort pulsed lasers have been widely used for the precise processing of optically transparent materials, including biodegradable polymers. Here, we demonstrated the change in the biodegradation of a poly(lactic-co-glycolic acid) (PLGA) following irradiation with femtosecond laser pulses at different wavelengths. Microscopic observation as well as water absorption and mass change measurement revealed that the biodegradation of the PLGA varied significantly depending on the laser wavelength. There was a significant acceleration of the degradation rate upon 400 nm-laser irradiation, whereas 800 nm-laser irradiation did not induce a comparable degree of change. The X-ray photoelectron spectroscopy analysis indicated that laser pulses at the shorter wavelength dissociated the chemical bonds effectively, resulting in a higher degradation rate at an early stage of degradation.

  10. Release of propranolol and diclofenac from low Mw DL-poly(lactic acid).

    PubMed

    Mamouzelos, N J; Proikakis, C S; Tarantili, P A; Andreopoulos, A G

    2002-01-01

    The controlled release of two drugs, i.e. the sodium salt of diclofenac and propranolol was studied, by using low molecular weight D,L-Poly(lactic acid) as a matrix. Tablets of the above polymer containing those drugs were immersed into buffers with various pH values and delivery was recorded as a function of time, via UV-spectroscopy. The results showed that the polymer is appropriate for such biomedical applications, as generally, it ensures complete drug delivery within 45-60 days, which is acceptable for most cases. On the other hand, the release rate depends on many parameters including the interactions among drug, matrix and the surrounding liquid, which adds complexity to the process and requires careful investigation for proper design of a controlled release system.

  11. Preparation of spherical macroporous poly(lactic-co-glycolic acid) for bone tissue regeneration.

    PubMed

    Bian, Chunhui; Lin, Huiming; Li, Xiaofeng; Ma, Jie; Jiang, Pingping; Qu, Fengyu

    2015-02-01

    Spherical macroporous poly(lactic-co-glycolic acid) (PLGA) has been synthesised using an emulsion method. Polyvinyl alcohol and Pluronic F127 have been used as dispersing and porogen agent, respectively. The diameter of the spherical PLGA is about 20 μm and the pore size of the PLGA macroporous is about 2-2.5 μm observed by scanning electron microscopy. After immersing in simulated body fluid, the PLGA materials can induce the formation of hydroxyapatite (HAP) on their surface. The HAP-PLGA has been obtained and used as the host for drug release. Furthermore, the drug-loaded samples possess the various drug release performance by adjusting the thickness of the HAP layer. This highly satisfied composite material is expected to be promising in the applications in tissue regeneration engineering.

  12. Preparation of polypyrrole-embedded electrospun poly(lactic acid) nanofibrous scaffolds for nerve tissue engineering

    PubMed Central

    Zhou, Jun-feng; Wang, Yi-guo; Cheng, Liang; Wu, Zhao; Sun, Xiao-dan; Peng, Jiang

    2016-01-01

    Polypyrrole (PPy) is a biocompatible polymer with good conductivity. Studies combining PPy with electrospinning have been reported; however, the associated decrease in PPy conductivity has not yet been resolved. We embedded PPy into poly(lactic acid) (PLA) nanofibers via electrospinning and fabricated a PLA/PPy nanofibrous scaffold containing 15% PPy with sustained conductivity and aligned topography. There was good biocompatibility between the scaffold and human umbilical cord mesenchymal stem cells as well as Schwann cells. Additionally, the direction of cell elongation on the scaffold was parallel to the direction of fibers. Our findings suggest that the aligned PLA/PPy nanofibrous scaffold is a promising biomaterial for peripheral nerve regeneration. PMID:27904497

  13. Micro/nanofabrication of poly(L-lactic acid) using focused ion beam direct etching

    NASA Astrophysics Data System (ADS)

    Oyama, Tomoko Gowa; Hinata, Toru; Nagasawa, Naotsugu; Oshima, Akihiro; Washio, Masakazu; Tagawa, Seiichi; Taguchi, Mitsumasa

    2013-10-01

    Micro/nanofabrication of biocompatible and biodegradable poly(L-lactic acid) (PLLA) using focused Ga ion beam direct etching was evaluated for future bio-device applications. The fabrication performance was determined with different ion fluences and fluxes (beam currents), and it was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat. Focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds. Controlled micro/nanostructures of PLLA were fabricated with C=C bond-rich surfaces expected to have good cell attachment properties.

  14. Poly(lactic acid)/natural rubber/cellulose nanocrystal bionanocomposites. Part II: properties evaluation.

    PubMed

    Bitinis, Natacha; Fortunati, Elena; Verdejo, Raquel; Bras, Julien; Kenny, Jose Maria; Torre, Luigi; López-Manchado, Miguel Angel

    2013-07-25

    The crystallization, mechanical and biodegradation properties of poly(lactic acid)/natural rubber/cellulose nanocrystals (CNC) bionanocomposites were evaluated. Three types of CNC were used in this study, one unmodified (CNC), long alkyl chain grafted CNC (C18-g-CNC) and PLA grafted CNC (PLA-g-CNC). The CNC modifications determined the affinity of the nanocrystals toward the polymers and reflected on the ultimate properties. Interestingly, PLA-g-CNC acted as a nucleating agent for the PLA matrix in the bio-based PLA/NR blend. Good mechanical properties were reported, as the bionanocomposites maintained a high elongation at break for a concentration up to 3 wt.% of cellulose nanocrystals. Moreover, the disintegration study confirmed that the materials completely disintegrated after one month in compost.

  15. Fabrication of superhydrophobic surfaces via CaCO3 mineralization mediated by poly(glutamic acid)

    NASA Astrophysics Data System (ADS)

    Cao, Heng; Yao, Jinrong; Shao, Zhengzhong

    2013-03-01

    Surfaces with micrometer and nanometer sized hierarchical structures were fabricated by an one-step in situ additive controlled CaCO3 mineralization method. After chemical modification, the surfaces with various morphologies showed superhydrophobicity in different states, which could be easily adjusted by the initial supersaturation of the mineralization solution (concentration of calcium ion and poly(glutamic acid)). Generally, the "lotus state" surface which was covered by a thick layer of tetrahedron-shaped CaCO3 particles to exhibit a contact angle (CA) of 157±1° and a very low contact angle hysteresis (CAH) (roll-off angle=1°) was produced under high supersaturation. On the other hands, the petal-like surface with flower-shaped calcite spherulites was obtained in a relative low supersaturation, which showed both high CA (156±2°) and CAH (180°) in a "Cassie impregnating wetting state".

  16. Electrohydrodynamic encapsulation of cisplatin in poly (lactic-co-glycolic acid) nanoparticles for controlled drug delivery.

    PubMed

    Parhizkar, Maryam; Reardon, Philip J T; Knowles, Jonathan C; Browning, Richard J; Stride, Eleanor; Barbara, Pedley R; Harker, Anthony H; Edirisinghe, Mohan

    2016-10-01

    Targeted delivery of potent, toxic chemotherapy drugs, such as cisplatin, is a significant area of research in cancer treatment. In this study, cisplatin was successfully encapsulated with high efficiency (>70%) in poly (lactic-co-glycolic acid) polymeric nanoparticles by using electrohydrodynamic atomization (EHDA) where applied voltage and solution flow rate as well as the concentration of cisplatin and polymer were varied to control the size of the particles. Thus, nanoparticles were produced with three different drug:polymer ratios (2.5, 5 and 10wt% cisplatin). It was shown that smaller nanoparticles were produced with 10wt% cisplatin. Furthermore, these demonstrated the best sustained release (smallest burst release). By fitting the experimental data with various kinetic models it was concluded that the release is dependent upon the particle morphology and the drug concentration. Thus, these particles have significant potential for cisplatin delivery with controlled dosage and release period that are crucial chemotherapy parameters.

  17. Fabrication of multifunctional cellulose nanocrystals/poly(lactic acid) nanocomposites with silver nanoparticles by spraying method.

    PubMed

    Yu, Hou-Yong; Yang, Xing-Yuan; Lu, Fang-Fang; Chen, Guo-Yin; Yao, Ju-Ming

    2016-04-20

    The poly (lactic acid) (PLA)/functionalized cellulose nanocrystals formates (CNFs) were prepared by solution casting and then the binary films were sprayed with silver ammonia aqueous solution to fabricate PLA/CNF/Ag ternary nanocomposites. It was found that both deposited silver (Ag) nanoparticles and CNFs showed efficient reinforcing effect on the thermal, mechanical, barrier properties and antibacterial activity of PLA matrix. Especially, the maximum decomposition temperature (Tmax) and Young's modulus of PLA/CNF/Ag(6) nanocomposite film increased by 15.5°C and 48.7%, respectively. Meanwhile an obvious reduction in the water vapor permeability was detected. Furthermore, the migration levels of the ternary nanocomposite films were well below the permitted limits in both non-polar and polar food simulants (60mgkg(-1)), and they showed a significant antibacterial activity influenced by the Ag contents. This study reveals that the novel nanocomposite films will offer a good perspective for food packaging applications.

  18. Direct determination of creatinine based on poly(ethyleneimine)/phosphotungstic acid multilayer modified electrode.

    PubMed

    Han, Ping; Xu, Shimei; Feng, Shun; Hao, Yanjun; Wang, Jide

    2016-05-01

    In this work, the direct determination of creatinine was achieved using a poly(ethyleneimine)/phosphotungstic acid multilayer modified electrode with the assistance of Copper(II) ions by cyclic voltammetry. The quantity of creatinine were determined by measuring the redox peak current of Cu(II)-creatinine complex/Cu(I)-creatinine complex. Factors affecting the response current of creatinine at the modified electrode were optimized. A linear relationship between the response current and the concentration of creatinine ranging from 0.125 to 62.5μM was obtained with a detection limit of 0.06μM. The proposed method was applied to determine creatinine in human urine, and satisfied results were gotten which was validated in accordance with high performance liquid chromatography. The proposed electrode provided a promising alternative in routine sensing for creatinine without enzymatic assistance.

  19. Electrospinning of curcumin loaded chitosan/poly (lactic acid) nanofilm and evaluation of its medicinal characteristics

    NASA Astrophysics Data System (ADS)

    Dhurai, Bhaarathi; Saraswathy, Nachimuthu; Maheswaran, Ramasamy; Sethupathi, Ponnusamy; Vanitha, Palanisamy; Vigneshwaran, Sukumar; Rameshbabu, Venugopal

    2013-12-01

    The curcumin loaded chitosan/poly (lactic acid) (PLA) nanofibers were produced using electrospinning. Box—Behnken experimental design was used for the optimization of variables (-1, 0, + 1 coded level) like chitosan/PLA strength (% w/v), curcumin strength (% w/v) and applied voltage (kV) to obtain uniform fiber diameter. The morphology of nanofibers was shown by SEM. Molecular interactions and the presence of each chemical compound of curcumin loaded chitosan/PLA fibers were characterized by FTIR and EDX analysis. Antioxidant, drug release and in vitro cytotoxicity tests were performed to evaluate the suitability of nanofibers that would be used for wound healing. In vivo wound healing studies on excision and incision wounds created on rat model showed significant reduction of wound area when compared to untreated. The better healing efficiency can be attributed to the presence of curcumin and chitosan.

  20. Fabrication of novel calcium phosphate/poly(lactic acid) fiber composites.

    PubMed

    Kothapalli, Chandrasekhar R; Shaw, Montgomery T; Olson, James R; Wei, Mei

    2008-01-01

    Composites using high-modulus polylactic acid (PLA) fibers coated with calcium phosphate (CaP) were prepared using a cyclic precipitation technique. Scanning electron microscopy revealed that small nuclei of CaP formed after the first soaking cycle, while large quantities of CaP particles were observed after the sixth cycle. The amount of CaP deposited on the PLA yarn increased with deposition time in Ca(2+) and PO(4) (3-) solutions and number of cycles, and decreased with stirring rate during washing cycles. It was observed that around 35 wt % of CaP was deposited on the yarn surface after six cycles of cyclic-soaking. Based on the results, a heterogeneous nucleation and growth mechanism was proposed for the CaP deposition on the surface of hydrolyzed polyester. Composites comprising the coated fibers in a poly(caprolactone) matrix exhibited flexural moduli within the range of that of the cortical bone.

  1. Sorption of Pb(ll) by poly(hydroxamic acid) grafted oil palm empty fruit bunch.

    PubMed

    Haron, M J; Tiansin, M; Ibrahim, N A; Kassim, A; Wan Yunus, W M Z; Talebi, S M

    2011-01-01

    This paper describes the sorption of Pb(ll) from aqueous solution. Oil palm empty fruit bunch (OPEFB) fiber was first grafted with poly(methylacrylate) and then treated with hydroxylammonium chloride in alkaline medium to produce hydroxamic acid (PHA) grafted OPEFB. Sorption of Pb(ll) by PHA-OPEFB was maximum at pH 5. The sorption followed the Langmuir model with maximum capacityof 125.0 mg g-1 at 25 degrees C. The sorption process was exothermic, as shown by the negative value of enthalpy change, Delta H0. The free energy change (DeltaG0) for the sorption was negative, showing that the sorption process was spontaneous. A kinetic study showed that the Pb(ll) sorption followed a second order kinetic model.

  2. Self-assembling of poly(aspartic acid) with bovine serum albumin in aqueous solutions.

    PubMed

    Nita, L E; Chiriac, A P; Bercea, M; Asandulesa, M; Wolf, Bernhard A

    2017-02-01

    Macromolecular co-assemblies built up in aqueous solutions, by using a linear polypeptide, poly(aspartic acid) (PAS), and a globular protein, bovine serum albumin (BSA), have been studied. The main interest was to identify the optimum conditions for an interpenetrated complex formation in order to design materials suitable for biomedical applications, such as drug delivery systems. BSA surface possesses several amino- and carboxylic groups available for covalent modification, and/or bioactive substances attachment. In the present study, mixtures between PAS and BSA were investigated at 37°C in dilute aqueous solution by viscometry, dynamic light scattering and zeta potential determination, as well as in solid state by AFM microscopy and dielectric spectroscopy. The experimental data have shown that the interpolymer complex formation occurs for a PAS/BSA molar ratio around 0.541.

  3. Monolithic calcium phosphate/poly(lactic acid) composite versus calcium phosphate-coated poly(lactic acid) for support of osteogenic differentiation of human mesenchymal stromal cells.

    PubMed

    Tahmasebi Birgani, Zeinab; van Blitterswijk, Clemens A; Habibovic, Pamela

    2016-03-01

    Calcium phosphates (CaPs), extensively used synthetic bone graft substitutes, are often combined with other materials with the aim to overcome issues related to poor mechanical properties of most CaP ceramics. Thin ceramic coatings on metallic implants and polymer-ceramic composites are examples of such hybrid materials. Both the properties of the CaP used and the method of incorporation into a hybrid structure are determinant for the bioactivity of the final construct. In the present study, a monolithic composite comprising nano-sized CaP and poly(lactic acid) (PLA) and a CaP-coated PLA were comparatively investigated for their ability to support proliferation and osteogenic differentiation of bone marrow-derived human mesenchymal stromal cells (hMSCs). Both, the PLA/CaP composite, produced using physical mixing and extrusion and CaP-coated PLA, resulting from a biomimetic coating process at near-physiological conditions, supported proliferation of hMSCs with highest rates at PLA/CaP composite. Enzymatic alkaline phosphatase activity as well as the mRNA expression of bone morphogenetic protein-2, osteopontin and osteocalcin were higher on the composite and coated polymer as compared to the PLA control, while no significant differences were observed between the two methods of combining CaP and PLA. The results of this study confirmed the importance of CaP in osteogenic differentiation while the exact properties and the method of incorporation into the hybrid material played a less prominent role.

  4. UV protective poly(lactic acid)/rosin films for sustainable packaging.

    PubMed

    Narayanan, Meenu; Loganathan, Sravanthi; Valapa, Ravi Babu; Thomas, Sabu; Varghese, T O

    2017-06-01

    Recently, biopolymer based plastic materials are regarded as potential alternative for conventional plastics of fossil fuel origin in order to compensate depleting petroleum resources and address environmental pollution issues. Poly(lactic acid) (PLA) is one among the biopolymers which is rapidly commercialized for food packaging application. However, the demerits accompanied with PLA like brittle nature, slower crystallization rate, poor gas barrier and high ultraviolet radiation transmission properties confines its commercial application in food packaging sector. Studies on the improvement of ductility, crystallization rate and gas barrier properties are markedly reported. Much emphasis is not given in the literature on improving UV shielding properties which plays important role in preventing oxidation degradation of PLA. Therefore, the current work is focused on fabrication of eco-friendly poly(lactic acid)/rosin (RS) based biocomposite films with improved UV shielding along with ductility and oxygen barrier properties. The PLA-RS biocomposite films containing different loadings (1, 3, 5, 10 and 20wt%) of RS with an average thickness of 50μm are fabricated via solution casting technique. The PLA-RS film demonstrated noteworthy light barrier feature by shielding the passage of ∼98%, 92% and 53% in UV-B, UV-A and visible light regime, respectively. In case of UV-C region, complete blockage of UV transmission through the PLA-RS biocomposite film is noticed. In addition to this, the presence of RS in the PLA matrix brought considerable improvement in terms of ductility and oxygen barrier characteristics. This in turn indicates PLA-RS biocomposite films hold significant potential for sustainable food packaging application.

  5. Antimicrobial biomaterials based on carbon nanotubes dispersed in poly(lactic-co-glycolic acid)

    NASA Astrophysics Data System (ADS)

    Aslan, Seyma; Loebick, Codruta Zoican; Kang, Seoktae; Elimelech, Menachem; Pfefferle, Lisa D.; van Tassel, Paul R.

    2010-09-01

    Biomaterials that inactivate microbes are needed to eliminate medical device infections. We investigate here the antimicrobial nature of single-walled carbon nanotubes (SWNTs) incorporated within the biomedical polymer poly(lactic-co-glycolic acid) (PLGA). We find Escherichia coli and Staphylococcus epidermidis viability and metabolic activity to be significantly diminished in the presence of SWNT-PLGA, and to correlate with SWNT length and concentration (<2% by weight). Up to 98% of bacteria die within one hour on SWNT-PLGA versus 15-20% on pure PLGA. Shorter SWNTs are more toxic, possibly due to increased density of open tube ends. This study demonstrates the potential usefulness of SWNT-PLGA as an antimicrobial biomaterial.Biomaterials that inactivate microbes are needed to eliminate medical device infections. We investigate here the antimicrobial nature of single-walled carbon nanotubes (SWNTs) incorporated within the biomedical polymer poly(lactic-co-glycolic acid) (PLGA). We find Escherichia coli and Staphylococcus epidermidis viability and metabolic activity to be significantly diminished in the presence of SWNT-PLGA, and to correlate with SWNT length and concentration (<2% by weight). Up to 98% of bacteria die within one hour on SWNT-PLGA versus 15-20% on pure PLGA. Shorter SWNTs are more toxic, possibly due to increased density of open tube ends. This study demonstrates the potential usefulness of SWNT-PLGA as an antimicrobial biomaterial. Electronic supplementary information (ESI) available: Raman spectra before and after SWNT cutting via cyclodextrins, and sample images from viability and metabolic activity assays are included. See DOI: 10.1039/c0nr00329h

  6. Calcium-activated gene transfection from DNA/poly(amic acid-co-imide) complexes

    PubMed Central

    Wu, Szu-Yuan; Chang, Li-Ting; Peng, Sydeny; Tsai, Hsieh-Chih

    2015-01-01

    In this study, we synthesized a water-soluble poly(amic acid-co-imide) (PA-I) from ethylenediaminetetraacetic dianhydride (EDTA) and 2,2′-(ethylenedioxy)bis(ethylamine) that possesses comparable transfection efficiency to that of polyethylenimine (PEI), when prepared in combination with divalent calcium cations. The polycondensation of monomers afforded poly(amic acid) (PA) precursors, and subsequent thermal imidization resulted in the formation of PA-I. At a polymer/DNA ratio (indicated by the molar ratio of nitrogen in the polymer to phosphate in DNA) of 40, complete retardation of the DNA band was observed by gel electrophoresis, indicating the strong association of DNA with PA-I. A zeta potential of −22 mV was recorded for the PA-I polymer solution, and no apparent cytotoxicity was observed at concentrations up to 500 μg·mL−1. In the presence of divalent Ca2+, the transfection efficiency of PA-I was higher than that of PA, due to the formation of a copolymer/Ca2+/DNA polyplex and the reduction in negative charge due to thermal cyclization. Interestingly, a synergistic effect of Ca2+ and the synthesized copolymer on DNA transfection was observed. The use of Ca2+ or copolymer alone resulted in unsatisfactory delivery, whereas the formation of three-component polyplexes synergistically increased DNA transfection. Our findings demonstrated that a PA-I/Ca2+/DNA polyplex could serve as a promising candidate for gene delivery. PMID:25767385

  7. Light scattering study of partially ionized poly(acrylic acid) systems : comparison between gels and solutions

    NASA Astrophysics Data System (ADS)

    Moussaid, A.; Munch, J. P.; Schosseler, F.; Candau, S. J.

    1991-06-01

    Static and quasielastic light scattering experiments have been performed on the reaction bath of partially neutralized poly(acrylic acid) solutions and gels. The intensity scattered from gels is independent on the scattering wavevector, giving thus evidence that the gels are homogeneous at the scale of the wavelength of the light, contrary to what is generally observed in neutral gels. The comparison of the time and ensemble averages of the autocorrelation function of scattered light intensity shows that the gels behave with respect to that experiment as ergodic media. The variations of the intensity scattered from gels and solutions, with the ionization degree and the polymer concentration were found to be in good agreement with those predicted from simple theoretical arguments. The variations of the cooperative diffusion with these same parameters were found similar for gels and solutions. Des mesures de diffusion statique et quasiélastique de la lumière ont été effectuées sur des solutions et des gels d'acide poly(acrylique) partiellement ionisés. L'intensité diffusée par les gels est indépendante du vecteur d'onde de transfert, ce qui montre leur homogénéité, contrairement au cas des gels neutres. La comparaison des moyennes temporelle et spatiale de la fonction d'autocorrélation de l'intensité de la lumière diffusée montre que ces gels se comportent comme des milieux ergodiques. Les variations de l'intensité diffusée par les gels et les solutions en fonction de la concentration en polymère et du degré d'ionisation sont en bon accord avec les prédictions théoriques. Les variations du coefficient de diffusion avec ces mêmes paramètres sont identiques pour les gels et les solutions.

  8. Thermal Properties of Extruded Injection-Molded Poly (lactic acid) and Milkweed Composites: Degradation Kinectics and Enthalpic Relaxation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to determine the degree of compatibility between Poly (lactic Acid) (PLA) and different biomaterials, PLA was compounded with milkweed fiber, a new crop oil seed. After oil extraction, the remaining cake retained approximately 10% residual oil and 47% protein. The pressed seed cake (10% mo...

  9. Electrospining of polyaniline/poly(lactic acid) ultrathin fibers: process and statistical modeling using a non-gaussian approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cover: The electrospinning technique was employed to obtain conducting nanofibers based on polyaniline and poly(lactic acid). A statistical model was employed to describe how the process factors (solution concentration, applied voltage, and flow rate) govern the fiber dimensions. Nanofibers down to ...

  10. Antibacterial poly(lactic acid) (PLA) films grafting electrospun PLA/Ally isothioscyanate (AITC) fibers for food packaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly(lactic acid) (PLA) fibers of submicron sizes encapsulating allyl isothiocyanate (AITC) (PfA) were made and electrospun onto the surfaces of PLA films (PfA-g-film). SEM examination confirmed that the fibers were grafted to the PLA film after the (PfA-g-film) underwent air blowing and water washi...

  11. Degradation of Poly(L-Lactic Acid) and Bio-Composites by Alkaline Medium under Various Temperatures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ribbons of poly(lactic acid) (PLA) and PLA containing 10 or 25 % Osage orange (OO) biocomposites of various sized heartwood particles were exposed to non-composting soil conditions either outdoors or in a greenhouse. No appreciable degradation was evident even after 208 day treatments. An artifici...

  12. Thermal properties of extruded injection-molded poly (lactic acid) and milkweed composites: degradation kinetics and enthalpic relaxation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Currently, most polymer composites utilize petroleum-based materials that are non-degradable and difficult to recycle or incur substantial cost for disposal. Green composites can be used in nondurable limited applications. In order to determine the degree of compatibility between Poly (lactic Acid...

  13. In vitro antimicrobial activity of solution blow spun poly(lactic acid)/ polyvinylpyrrolidone nanofibers loaded with Copaiba (Copaifera sp.) oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study poly(lactic acid)(PLA) and polyvinylpyrrolidone (PVP) micro and nanofibers mats loaded with copaiba (Copaifera sp.) oil were produced by solution blow spinning (SBS). The copaiba (Copaifera sp.) oil was characterized by gas chromatography (GC). Neat PLA and four PLA/ PVP blends contain...

  14. Production of Pullulan, Poly(beta-L-malic acid), and Heavy Oil by Fungus Aureobasidium pullulans Isolated from Thailand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fungus Aureobasidium pullulans is the main source of a polysaccharide, pullulan, in industrial production. Moreover, it can produce many bioproducts, e.g. xylanase, poly(ß-L-malic acid) (PMA), and heavy oil. In this study, we isolated 15 A. pullulans isolates from various sources and habitats in T...

  15. A stencil printed, high energy density silver oxide battery using a novel photopolymerizable poly(acrylic acid) separator.

    PubMed

    Braam, Kyle; Subramanian, Vivek

    2015-01-27

    A novel photopolymerized poly(acrylic acid) separator is demonstrated in a printed, high-energy-density silver oxide battery. The printed battery demonstrates a high capacity of 5.4 mA h cm(-2) at a discharge current density of 2.75 mA cm(-2) (C/2 rate) while delivering good mechanical flexibility and robustness.

  16. Stereoregularity of poly (lactic acid) and their model compounds as studied by NMR and quantum chemical calculations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to understand the origin of the tacticity splitting in the NMR spectrum of poly(lactic acid), monomer model compound and dimer model compounds (both isotactic and syndiotactic) were synthesized and their 1H and 13C NMR chemical shifts observed. Two energetically stable conformations were o...

  17. Preparation of starch-poly-glutamic acid graft copolymers by microwave irradiation and the characterization of their properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Graft copolymers of waxy maize starch and poly-y-glutamic acid (PGA) were produced in an aqueous solution using microwave irradiation. The microwave reaction conditions were optimized with regard to temperature and pH. The temperature of 180 deg C and pH 7.0 were the best reaction conditions resulti...

  18. Effects of material thickness and processing method on poly(lactic-co-glycolic acid) degradation and mechanical performance.

    PubMed

    Shirazi, Reyhaneh Neghabat; Aldabbagh, Fawaz; Ronan, William; Erxleben, Andrea; Rochev, Yury; McHugh, Peter

    2016-10-01

    In this study, the effects of material thickness and processing method on the degradation rate and the changes in the mechanical properties of poly(lactic-co-glycolic acid) material during simulated physiological degradation were investigated. Two types of poly(lactic-co-glycolic acid) materials were considered: 0.12 mm solvent-cast films and 1 mm compression-moulded plates. The experimental results presented in this study were compared to the experimental results of Shirazi et al. (Acta Biomaterialia 10(11):4695-703, 2014) for 0.25 mm solvent-cast films. These experimental observations were used to validate the computational modelling predictions of Shirazi et al. (J Mech Behav Biomed Mater 54: 48-59, 2016) on critical diffusion length scale and also to refine the model parameters. The specific material processing methods considered here did not have a significant effect on the degradation rate and the changes in mechanical properties during degradation; however, they influenced the initial molecular weight and they determined the stiffness and hardness of the poly(lactic-co-glycolic acid) material. The experimental observations strongly supported the computational modelling predictions that showed no significant difference in the degradation rate and the changes in the elastic modulus of poly(lactic-co-glycolic acid) films for thicknesses larger than 100 μm.

  19. Performance enhancement of poly(lactic acid)/soy protein concentrate blends by promoting formation of network structure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this work, the effects of water content in preformulated soy protein concentrate (SPC) and of SPC content on the thermal, rheological and mechanical properties and morphology of poly(lactic acid) (PLA)/SPC blends were studied. The blends were prepared by twin screw compounding and the test specim...

  20. Characterization of bioactive RGD peptide immobilized onto poly(acrylic acid) thin films by plasma polymerization

    NASA Astrophysics Data System (ADS)

    Seo, Hyun Suk; Ko, Yeong Mu; Shim, Jae Won; Lim, Yun Kyong; Kook, Joong-Ki; Cho, Dong-Lyun; Kim, Byung Hoon

    2010-11-01

    Plasma surface modification can be used to improve the surface properties of commercial pure Ti by creating functional groups to produce bioactive materials with different surface topography. In this study, a titanium surface was modified with acrylic acid (AA) using a plasma treatment and immobilized with bioactive arginine-glycine-aspartic acid (RGD) peptide, which may accelerate the tissue integration of bone implants. Both terminals containing the -NH2 of RGD peptide sequence and -COOH of poly(acrylic acid) (PAA) thin film were combined with a covalent bond in the presence of 1-ethyl-3-3-dimethylaminopropyl carbodiimide (EDC). The chemical structure and morphology of AA film and RGD immobilized surface were investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). All chemical analysis showed full coverage of the Ti substrate with the PAA thin film containing COOH groups and the RGD peptide. The MC3T3-E1 cells were cultured on each specimen, and the cell alkaline phosphatase (ALP) activity were examined. The surface-immobilized RGD peptide has a significantly increased the ALP activity of MC3T3-E1 cells. These results suggest that the RGD peptide immobilization on the titanium surface has an effect on osteoblastic differentiation of MC3T3-E1 cells and potential use in osteo-conductive bone implants.

  1. Enhanced production of poly-γ-glutamic acid by a newly-isolated Bacillus subtilis.

    PubMed

    Ju, Wan-Taek; Song, Yong-Su; Jung, Woo-Jin; Park, Ro-Dong

    2014-11-01

    Application of poly-gamma-glutamic acid (γ-PGA), an unusual macromolecular anionic polypeptide, is limited due to the high cost associated with its low productivity. Screening bacterial strains to find a more efficient producer is one approach to overcome this limitation. Strain MJ80 was isolated as a γ-PGA producer among 1,500 bacterial colonies obtained from soil samples. It was identified as Bacillus subtilis, based on the biochemical and morphological properties and 16S rDNA gene sequencing. It produced γ-PGA from both glutamic acid and soybean powder, identifying it as a facultative glutamic acid-metabolizing bacterium. After optimization of its culture conditions, B. subtilis MJ80 showed γ-PGA productivity of 75.5 and 68.7 g/l in 3 and 300 l jar fermenters for 3 days cultivation, respectively, the highest productivity reported to date, suggesting MJ80 to be a promising strain for γ-PGA production.

  2. Poly(o-aminophenol)-modified bienzyme carbon paste electrode for the detection of uric acid.

    PubMed

    Miland, E; Miranda Ordieres, A J; Tuñón Blanco, P; Smyth, M R; Fágáin, C O

    1996-05-01

    A reagentless uric acid selective biosensor constructed by immobilising uricase and horseradish peroxidase (HRP) in carbon paste without the addition of an electron transfer mediator is described. The response of the electrode is based on the enzymatic reduction of hydrogen peroxide in the presence of uric acid. Uricase and HRP were dispersed in the carbon paste and the optimum paste mixture was determined. Poly(o-aminophenol) was electropolymerised at the working surface area of the electrode acting as a conducting polymer layer. Cyclic voltammetry was used to characterise the permselective characteristics of the polymer layer. At an applied potential of 50 mV vs. Ag/AgCl, a linear response was obtained up to 1 x 10(-4) M, with a limit of detection of 3 x 10(-6) M. The sensor had a response time of 37 s. a calibration precision of 2.2% (n = 4) and an estimated sample frequency of 20 h(-1). Responses to the analyte of interest were pH dependent. The sensor was incorporated into a flow injection system for the qualification of uric acid in human serum. Results compared favourably with a standard spectrophotometric method.

  3. pH-Responsive Behavior of Poly(acrylic acid) Brushes of Varying Thickness

    NASA Astrophysics Data System (ADS)

    Yadav, Vivek; Robertson, Megan; Conrad, Jacinta

    2015-03-01

    We have investigated the pH-dependent response of polyelectrolyte brushes of varying thickness. Our model system consists of poly(acrylic acid) brushes, which change from hydrophobic and neutral at low pH to hydrophilic and negatively charged at high pH, synthesized using a grafting-from approach at constant grafting density. As the polymer brush thickness increased, the brushes exhibited greater hysteresis in static water contact angle as a function of pH. We extracted the pKa of the polymer brushes from contact angle measurements. The relationship between the pKa and brush thickness depended on the order in which the brushes were exposed to solutions of varying pH: pKa decreased on increasing brush thickness when going from basic to acidic medium whereas pKa increased on increasing brush thickness when going from acidic to basic medium. We speculate that the origin of hysteresis can be explained by pH-dependent conformational changes in these polyelectrolyte brushes.

  4. Positive mode electrospray tandem mass spectrometry of poly(methacrylic acid) oligomers.

    PubMed

    Giordanengo, Rémi; Viel, Stéphane; Allard-Breton, Béatrice; Thévand, André; Charles, Laurence

    2009-06-01

    The dissociation of small poly(methacrylic acid) (PMAA) cations produced by electrospray was characterized by tandem mass spectrometry. Similarly to PMAA ions produced in the negative ion mode, the two electrosprayed cationic forms, namely [PMAA+Na](+) and [PMAA-H+2Na](+), were shown to fragment via a major pathway consisting of successive dehydration steps. Elimination of a water molecule would occur between two consecutive acid groups in a charged-remote mechanism and was shown to proceed as many times as pairs of acidic pendant groups were available. As a result, comparing the number of dehydration steps observed in the MS/MS spectrum of two consecutive oligomers from the polymeric distribution reveals the degree of polymerization of the molecule. Secondary less informative reactions were shown to consist of losses of CO and/or CO(2), depending on the nature of the precursor ion. These fragmentation rules could be used to characterize PMAA-based copolymers, as successfully demonstrated for a polymeric impurity in the tested PMAA sample.

  5. Thermal degradation behaviour of nanoamphiphilic chitosan dispersed poly (lactic acid) bionanocomposite films.

    PubMed

    Pal, Akhilesh Kumar; Katiyar, Vimal

    2017-02-01

    In the present study, nano-amphiphilic chitosan termed as chitosan-grafted-oligo l-lactic acid (CH-g-OLLA), is synthesized by microwave initiated insitu condensation polymerization. The synthesized CH-g-OLLA becomes hydrophobic in nature due to chemical bond formation between chitosan backbone and OLLA chains. Further, CH-g-OLLA (30%) bionanocomposite is used as a nanofiller in poly (lactic acid)/chitosan-grafted-oligo l-lactic acid (PLA/CH-g-OLLA) bionanocomposite films. Surface morphology shows a homogeneous dispersion of CH-g-OLLA in the form of spherical aggregates, which vary in the range of ∼20 to 150nm. Non-isothermal degradation kinetics, proposed by Kissinger, Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa and Augis & Bennett models, are utilized to estimate the activation energies (Ea) for PLA, which are 254.1, 260.2, 257.0 and 259.1kJmol(-1) respectively. The reduction in Ea values of bionanocomposite films may be elucidated by intermolecular distance and enrichment in chain mobility. The evolved gaseous products like hydrocarbons, carbon dioxide, carbon monoxide and cyclic oligomers are successfully identified with TG-FTIR analysis.

  6. Enhancement of osteoinduction by continual simvastatin release from poly(lactic-co-glycolic acid)-hydroxyapatite-simvastatin nano-fibrous scaffold.

    PubMed

    Jiang, Liming; Sun, Haizhu; Yuan, Anliang; Zhang, Kai; Li, Daowei; Li, Chen; Shi, Ce; Li, Xiangwei; Gao, Kai; Zheng, Changyu; Yang, Bai; Sun, Hongchen

    2013-11-01

    Simvastatin is considered as a stimulator for bone formation. However, the half-life for simvastatin is generally 2 hours, which means, it is difficult to maintain biologically active simvastatin in vivo. To overcome this limitation, we created a system to slowly release simvastatin in vitro and in vivo. We constructed a poly(lactic-co-glycolic acid)/hydroxyapatite nano-fibrous scaffold to carry simvastatin. Releasing assays showed that simvastatin was released from poly(lactic-co-glycolic acid)/hydroxyapatite/simvastatin quickly within - 15 days, and small amounts continued to be released through day 56 (experiments terminated). MTT assays demonstrated that both poly(lactic-co-glycolic acid)/hydroxyapatite and poly(lactic-co-glycolic acid)/hydroxyapatite/simvastatin promoted MC3T3-E1 cell proliferation. However, Alkaline phosphatase assays showed that only poly(lactic-co-glycolic acid)/hydroxyapatite/simvastatin scaffold significantly promoted the osteogenic differentiation of MC3T3-E1 cells in vitro on day 14. To further test in vivo, we created calvaria bone defect models and implanted either poly(lactic-co-glycolic acid)/hydroxyapatite or poly(lactic-co-glycolic acid)/hydroxyapatite/simvastatin. After 4 or 8 weeks post-implantation, the results indicated that poly(lactic-co-glycolic acid)/hydroxyapatite/simvastatin scaffold induced bone formation more efficiently than poly(lactic-co-glycolic acid)/hydroxyapatite alone. Our data demonstrates that poly(lactic-co-glycolic acid)/hydroxyapatite/simvastatin has the potential to aid in healing bone defects and promoting bone regeneration in the future although we still need to optimize this complex to efficiently promote bone regeneration.

  7. A poly(3-acetylthiophene) modified glassy carbon electrode for selective voltammetric measurement of uric acid in urine sample.

    PubMed

    Aslanoglu, Mehmet; Kutluay, Aysegul; Abbasoglu, Sultan; Karabulut, Serpil

    2008-03-01

    A reliable and reproducible method for the determination of uric acid in urine samples has been developed. The method is based on the modification of a glassy carbon electrode by 3-acetylthiophene using cyclic voltammetry. The poly(3-acetylthiophene) modified glassy carbon electrode showed an excellent electrocatalytic effect towards the oxidation of uric acid in 0.1 m phosphate buffer solution (PBS) at pH 7.2. Compared with a bare glassy carbon electrode (GCE), an obvious shift of the oxidation peak potential in the cathodic direction and a marked enhancement of the anodic current response for uric acid were observed. The poly(3-acetylthiophene)/GCE was used for the determination of uric acid using square wave voltammetry. The peak current increased linearly with the concentration of uric acid in the range of 1.25 x 10(-5)-1.75 x 10(-4) M. The detection limit was 5.27 x 10(-7) M by square wave voltammetry. The poly(3-acetylthiophene)/GCE was also effective to determine uric acid and ascorbic acid in a mixture and resolved the overlapping anodic peaks of these two species into two well-defined voltammetric peaks in cyclic voltammetry at 0.030 V and 0.320 V (vs. Ag/AgCl) for ascorbic acid and uric acid, respectively. The modified electrode exhibited stable and sensitive current responses toward uric acid and ascorbic acid. The method has successfully been applied for determination of uric acid in urine samples.

  8. Economic process to co-produce poly(ε-l-lysine) and poly(l-diaminopropionic acid) by a pH and dissolved oxygen control strategy.

    PubMed

    Xu, Zhaoxian; Feng, Xiaohai; Sun, Zhuzhen; Cao, Changhong; Li, Sha; Xu, Zheng; Xu, Zongqi; Bo, Fangfang; Xu, Hong

    2015-01-01

    This study tended to apply biorefinery of indigenous microbes to the fermentation of target-product generation through a novel control strategy. A novel strategy for co-producing two valuable homopoly(amino acid)s, poly(ε-l-lysine) (ε-PL) and poly(l-diaminopropionic acid) (PDAP), was developed by controlling pH and dissolved oxygen concentrations in Streptomyces albulus PD-1 fermentation. The production of ε-PL and PDAP got 29.4 and 9.6gL(-1), respectively, via fed-batch cultivation in a 5L bioreactor. What is more, the highest production yield (21.8%) of similar production systems was achieved by using this novel strategy. To consider the economic-feasibility, large-scale production in a 1t fermentor was also implemented, which would increase the gross profit of 54,243.5USD from one fed-batch bioprocess. This type of fermentation, which produces multiple commercial products from a unified process is attractive, because it will improve the utilization rate of raw materials, enhance production value and enrich product variety.

  9. Poly(Acrylic Acid-b-Styrene) Amphiphilic Multiblock Copolymers as Building Blocks for the Assembly of Discrete Nanoparticles

    PubMed Central

    Greene, Anna C.; Zhu, Jiahua; Pochan, Darrin J.; Jia, Xinqiao; Kiick, Kristi L.

    2011-01-01

    In order to expand the utility of current polymeric micellar systems, we have developed amphiphilic multiblock copolymers containing alternating blocks of poly(acrylic acid) and poly(styrene). Heterotelechelic poly(tert-butyl acrylate-b-styrene) diblock copolymers containing an α-alkyne and an ω-azide were synthesized by atom transfer radical polymerization (ATRP), allowing control over the molecular weight while maintaining narrow polydispersity indices. The multiblock copolymers were constructed by copper-catalyzed azide-alkyne cycloaddition of azide-alkyne end functional diblock copolymers which were then characterized by 1H NMR, FT-IR and SEC. The tert-butyl moieties of the poly(tert-butyl acrylate-b-styrene) multiblock copolymers were easily removed to form the poly(acrylic acid-b-styrene) multiblock copolymer ((PAA-PS)9), which contained up to 9 diblock repeats. The amphiphilic multiblock (PAA-PS)9 (Mn = 73.3 kg/mol) was self-assembled by dissolution into tetrahydrofuran and extensive dialysis against deionized water for 4 days. The critical micelle concentration (CMC) for (PAA-PS)9 was determined by fluorescence spectroscopy using pyrene as a fluorescent probe and was found to be very low at 2 × 10-4 mg/mL. The (PAA-PS)9 multiblock was also analyzed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The hydrodynamic diameter of the particles was found to be 11 nm. Discrete spherical particles were observed by TEM with an average particle diameter of 14 nm. The poly(acrylic acid) periphery of the spherical particles should allow for future conjugation of biomolecules. PMID:21552373

  10. Composite biodegradable biopolymer coatings of silk fibroin - Poly(3-hydroxybutyric-acid-co-3-hydroxyvaleric-acid) for biomedical applications

    NASA Astrophysics Data System (ADS)

    Miroiu, Floralice Marimona; Stefan, Nicolaie; Visan, Anita Ioana; Nita, Cristina; Luculescu, Catalin Romeo; Rasoga, Oana; Socol, Marcela; Zgura, Irina; Cristescu, Rodica; Craciun, Doina; Socol, Gabriel

    2015-11-01

    Composite silk fibroin-poly(3-hydroxybutyric-acid-co-3-hydroxyvaleric-acid) (SF-PHBV) biodegradable coatings were grown by Matrix Assisted Pulsed Laser Evaporation on titanium substrates. Their physico-chemical properties and particularly the degradation behavior in simulated body fluid at 37 °C were studied as first step of applicability in local controlled release for tissue regeneration applications. SF and PHBV, natural biopolymers with excellent biocompatibility, but different biodegradability and tensile strength properties, were combined in a composite to improve their properties as coatings for biomedical uses. FTIR analyses showed the stoichiometric transfer from targets to coatings by the presence in the spectra of the main absorption maxima characteristic of both polymers. XRD investigations confirmed the FTIR results showing differences in crystallization behavior with respect to the SF and PHBV content. Contact angle values obtained through wettability measurements indicated the MAPLE deposited coatings were highly hydrophilic; surfaces turning hydrophobic with the increase of the PHBV component. Degradation assays proved that higher PHBV contents resulted in enhanced resistance and a slower degradation rate of composite coatings in SBF. Distinct drug-release schemes could be obtained by adjusting the SF:PHBV ratio to controllably tuning the coatings degradation rate, from rapid-release formulas, where SF predominates, to prolonged sustained ones, for larger PHBV content.

  11. Dual Enzyme-Responsive Capsules of Hyaluronic Acid-block-Poly(Lactic Acid) for Sensing Bacterial Enzymes.

    PubMed

    Tücking, Katrin-Stephanie; Grützner, Verena; Unger, Ronald E; Schönherr, Holger

    2015-07-01

    The synthesis of novel amphiphilic hyaluronic acid (HYA) and poly(lactic acid) (PLA) block copolymers is reported as the key element of a strategy to detect the presence of pathogenic bacterial enzymes. In addition to the formation of defined HYA-block-PLA assemblies, the encapsulation of fluorescent reporter dyes and the selective enzymatic degradation of the capsules by hyaluronidase and proteinase K are studied. The synthesis of the dual enzyme-responsive HYA-b-PLA is carried out by copper-catalyzed Huisgen 1,3-dipolar cycloaddition. The resulting copolymers are assembled in water to form vesicular structures, which are characterized by scanning electron microscopy, transmission electron microscopy, dynamic light scattering (DLS), and fluorescence lifetime imaging microscopy (FLIM). DLS measurements show that both enzymes cause a rapid decrease in the hydrodynamic diameter of the nanocapsules. Fluorescence spectroscopy data confirm the liberation of encapsulated dye, which indicates the disintegration of the capsules and validates the concept of enzymatically triggered payload release. Finally, cytotoxicity assays confirm that the HYA-b-PLA nanocapsules are biocompatible with primary human dermal microvascular endothelial cells.

  12. pH-Sensitive ionomeric particles obtained via chemical conjugation of silk with poly(amino acid)s.

    PubMed

    Serban, Monica A; Kaplan, David L

    2010-12-13

    Silk-fibroin-based biomaterials have been widely utilized for a range of biomaterial-related systems. For all these previously reported systems, the β-sheet forming feature of the silk was the key stabilizing element of the final material structure. Herein, we describe a different strategy, based on the engineering of silk-based ionomers that can yield stable colloidal composites or particle suspensions through electrostatic interactions. These silk-based ionomers were obtained by carbodiimide-mediated coupling of silk fibroin with polylysine hydrobromide and polyglutamic acid sodium salts, respectively. Colloidal composites could be obtained by mixing the ionomeric pair at high concentration (i.e., 25% w/v), while combining them at lower concentrations (i.e., 5% w/v) yielded particle suspensions. The assembly of the ionomers was driven by electrostatic interactions, pH-dependent, and reversible. The network assembly appeared to be polarized, with the interacting poly(amino acid) chains clustered to the core of the particles and the silk backbone oriented outward. In agreement with this assembly mode, doxorubicin, a hydrophilic antitumor drug, could be released at a slow rate, in a pH-dependent manner, indicating that the inside of the ionomeric particles was mainly hydrophilic in nature.

  13. Poly(acrylic acid) modified calcium phosphate cements: the effect of the composition of the cement powder and of the molecular weight and concentration of the polymeric acid.

    PubMed

    Majekodunmi, A O; Deb, S

    2007-09-01

    Polymer modified calcium phosphate cements made with cement powders of varying tetracalcium phosphate [TTCP] content were prepared using two different molecular weight fractions of poly(acrylic acid) at four different concentrations. The ratio of the precursors (TTCP:DCPA) in the cement powder was found to influence the initial setting which decreased with increasing concentration of TTCP in the powder phase. It was also observed that cements derived from the higher molecular weight containing PAA yielded significantly (P < 0.05) shorter initial setting time (Ti) than cements containing the lower molecular weight, poly(acrylic acid) [GE7 PAA] The effect of the varying the TTCP content in the three different cement types PCPC-A, PCPC-B and PCPC-C showed that the trends of the compressive strength were specific to the concentration and molecular weight of the poly (acrylic acid). A 20% concentration of Glascol-E7 with a cement powder composed of an equimolar ratio of precursors (PCPC-B) resulted in optimal compressive strength within the range investigated. The TTCP content of the cement powder could also be varied to improve the diametral tensile strengths of the cements; the specific effects however, were again governed by both the concentration and molecular weight of the constituent poly (acrylic acid). The influence of TTCP on both the initial setting time and diametral tensile strength was related to the Ca (2+) ion concentration, which determined the rate and amount of cross-linking in the cement.

  14. Complementary use of flow and sedimentation field-flow fractionation techniques for size characterizing biodegradable poly(lactic acid) nanospheres

    PubMed Central

    Contado, Catia; Dalpiaz, Alessandro; Leo, Eliana; Zborowski, Maciej; Williams, P. Stephen

    2009-01-01

    Poly(lactic acid) nanoparticles were synthesized using a modified evaporation method, testing two different surfactants (sodium cholate and Pluronic F68) for the process. During their formulation the prodrug 5′-octanoyl-CPA (Oct-CPA) of the antiischemic N6-cyclopentyladenosine (CPA) was encapsulated. Three different purification methods were compared with respect to the influence of surfactant on the size characteristics of the final nanoparticle product. Flow and sedimentation field-flow fractionation techniques (FlFFF and SdFFF, respectively) were used to size characterize the five poly(lactic acid) particle samples. Two different combinations of carrier solution (mobile phase) were employed in the FlFFF analyses, while a solution of poly(vinyl alcohol) was used as mobile phase for the SdFFF runs. The separation performances of the two techniques were compared and the particle size distributions, derived from the fractograms, were interpreted with the support of observations by scanning electron microscopy. Some critical aspects, such as the carrier choice and the channel thickness determination for the FlFFF, have been investigated. This is the first comprehensive comparison of the two FFF techniques for characterizing non standard particulate materials. The two FFF techniques proved to be complementary and gave good, congruent and very useful information on the size distributions of the five poly(lactic acid) particle samples. PMID:17482199

  15. Release of Water Soluble Drugs from Dynamically Swelling POLY(2-HYDROXYETHYL Methacrylate - CO - Methacrylic Acid) Hydrogels.

    NASA Astrophysics Data System (ADS)

    Kou, Jim Hwai-Cher

    In this study, ionizable copolymers of HEMA and methacrylic acid (MA) are investigated for their potential use in developing pH dependent oral delivery systems. Because of the MA units, these gels swell extensively at high pH. Since solute diffusion in the hydrophilic polymers depends highly on the water content of the matrix, it is anticipated that the release rate will be modulated by this pH induced swelling. From a practical point of view, the advantage of the present system is that one can minimize drug loss in the stomach and achieve a programmed release in intestine. This approach is expected to improve delivery of acid labile drugs or drugs that cause severe gastrointestinal side effects. This work mainly focuses on the basic understanding of the mechanism involved in drug release from the poly(HEMA -co- MA) gels, especially under dynamic swelling conditions. Equilibrium swelling is first characterized since water content is the major determinant of transport properties in these gels. Phenylpropanolamine (PPA) is chosen as the model drug for the release study and its diffusion characteristics in the gel matrix determined. The data obtained show that the PPA diffusivity follows the free volume theory of Yasuda, which explains the accelerating effect of swelling on drug release. A mathematical model based on a diffusion mechanism has been developed to describe PPA release from the swelling gels. Based on this model, several significant conclusions can be drawn. First, the release rate can be modulated by the aspect ratio of the cylindrical geometry, and this has a practical implication in dosage form design. Second, the release rate can be lowered quite considerably if the dimensional increase due to swelling is significant. Consequently, it is the balance between the drug diffusivity increase and the gel dimensional growth that determines the release rate from the swelling matrix. Third, quasi-steady release kinetics, which are characteristic of swelling

  16. Biocompatible and biodegradable poly(Tannic Acid) hydrogel with antimicrobial and antioxidant properties.

    PubMed

    Sahiner, Nurettin; Sagbas, Selin; Sahiner, Mehtap; Silan, Coskun; Aktas, Nahit; Turk, Mustafa

    2016-01-01

    A novel resourceful bulk poly(Tannic Acid) (p(TA)) hydrogel was prepared by crosslinking TA molecules with an epoxy crosslinker, trimethylolpropane triglycidyl ether (TMPGDE), in an autoclave at 90°C for 2h. The obtained p(TA) hydrogels were in disk form and have highly porous morphology. The swelling characteristics of p(TA) hydrogels were investigated in wound healing pH conditions of pH 5.4, 7.4, and 9 at 37.5°C, and the hydrogels showed good swelling and moisture content behavior. Especially, p(TA) hydrogels were found to be sensitive to pH 9 with 1669% maximum swelling. P(TA) hydrogels were completely degraded at pH 9 hydrolytically in 9 days. Total phenol contents and the effects of scavenging ABTS(+) radicals of degraded p(TA) hydrogels at pH 5.4, 7.4, and 9 were evaluated and calculated in terms of gallic acid equivalent and trolox equivalent antioxidant capacity, respectively, and found to be very effective. Moreover, degraded p(TA) hydrogels display strong antimicrobial behavior against gram positive Staphylococcus aureus, Bacillus subtilis, gram negative Pseudomonas aeruginosa bacteria strains and Candida albicans fungus strain. The WST-1 results indicated that bulk p(TA) hydrogels have no cyctotoxicity to the L929 fibroblast cell line in vitro.

  17. Locally delivered salicylic acid from a poly(anhydride-ester): impact on diabetic bone regeneration.

    PubMed

    Wada, Keisuke; Yu, Weiling; Elazizi, Mohamad; Barakat, Sandrine; Ouimet, Michelle A; Rosario-Meléndez, Roselin; Fiorellini, Joseph P; Graves, Dana T; Uhrich, Kathryn E

    2013-10-10

    Diabetes mellitus (DM) involves metabolic changes that can impair bone repair, including a prolonged inflammatory response. A salicylic acid-based poly(anhydride-ester) (SA-PAE) provides controlled and sustained release of salicylic acid (SA) that locally resolves inflammation. This study investigates the effect of polymer-controlled SA release on bone regeneration in diabetic rats where enhanced inflammation is expected. Fifty-six Sprague-Dawley rats were randomly assigned to two groups: diabetic group induced by streptozotocin (STZ) injection or normoglycemic controls injected with citrate buffer alone. Three weeks after hyperglycemia development or vehicle injection, 5mm critical sized defects were created at the rat mandibular angle and treated with SA-PAE/bone graft mixture or bone graft alone. Rats were euthanized 4 and 12weeks after surgery, then bone fill percentage in the defect region was assessed by micro-computed tomography (CT) and histomorphometry. It was observed that bone fill increased significantly at 4 and 12weeks in SA-PAE/bone graft-treated diabetic rats compared to diabetic rats receiving bone graft alone. Accelerated bone formation in normoglycemic rats caused by SA-PAE/bone graft treatment was observed at 4weeks but not at 12weeks. This study shows that treatment with SA-PAE enhances bone regeneration in diabetic rats and accelerates bone regeneration in normoglycemic animals.

  18. Identification and characterization of novel poly(DL-lactic acid) depolymerases from metagenome.

    PubMed

    Mayumi, Daisuke; Akutsu-Shigeno, Yukie; Uchiyama, Hiroo; Nomura, Nobuhiko; Nakajima-Kambe, Toshiaki

    2008-07-01

    Many poly(lactic acid) (PLA)-degrading microorganisms have been isolated from the natural environment by culture-based methods, but there is no study about unculturable PLA-degrading microorganisms. In this study, we constructed a metagenomic library consisting of the DNA extracted from PLA disks buried in compost. We identified three PLA-degrading genes encoding lipase or hydrolase. The purified enzymes degraded not only PLA, but also various aliphatic polyesters, tributyrin, and p-nitrophenyl esters. From their substrate specificities, the PLA depolymerases were classified into an esterase rather than a lipase. Among the PLA depolymerases, PlaM4 exhibited thermophilic properties; that is, it showed the highest activity at 70 degrees C and was stable even after incubation for 1 h at 50 degrees C. PlaM4 had absorption and degradation activities for solid PLA at 60 degrees C, which indicates that the enzyme can effectively degrade PLA in a high-temperature environment. On the other hand, the enzyme classification based on amino acid sequences showed that the other PLA depolymerases, PlaM7 and PlaM9, were not classified into known lipases or esterases. This is the first report on the identification and characterization of PLA depolymerase from a metagenome.

  19. Dopamine-conjugated poly(lactic-co-glycolic acid) nanoparticles for protein delivery to macrophages.

    PubMed

    Lee, Song Yi; Cho, Hyun-Jong

    2017-03-15

    Poly(lactic-co-glycolic acid)-dopamine (PLGA-D)-based nanoparticles (NPs) were developed for the delivery of protein to macrophages. PLGA-D was synthesized via amide bond formation between the amine group of D and the carboxylic acid group of PLGA. Bovine serum albumin (BSA, model protein) was encapsulated in PLGA NPs and PLGA-D NPs, which had an approximately 200nm mean diameter, <0.2 polydispersity index, and negative zeta potential value. There was no increment in the mean diameters of BSA-loaded NPs after 24h of incubation in biological fluid-simulated media (i.e., aqueous buffer and serum media). The primary, secondary, and tertiary structures of BSA released from the NPs were studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), circular dichroism, and fluorescence spectrophotometry; the structural stability of BSA was preserved during its encapsulation in the NPs and release from the NPs. PLGA/BSA NPs and PLGA-D/BSA NPs did not induce serious cytotoxicity in RAW 264.7 cells (mouse macrophage cell line) in an established concentration range. In RAW 264.7 cells, the intracellular accumulation of PLGA-D NPs was 2-fold higher than that of PLGA NPs. All of these findings indicated that PLGA-D NPs are a promising system for delivering proteins to macrophages.

  20. Formation of hierarchical molecular assemblies from poly(oxypropylene)-segmented amido acids under AFM tapping.

    PubMed

    Lin, Jiang-Jen; Tsai, Wei-Cheng; Wang, Chi-He

    2007-04-10

    Molecular self-aligning of amphiphilic molecules into bundles with a constant width of 7-13 nm was observed under tapping-mode atomic force microscopy (TM-AFM). The requisite amphiphile, a poly(oxypropylene)-trimellitic amido acid sodium salt, is constituted of a symmetric amido acid structure with potential noncovalent forces of ionic charges, hydrogen bonds, pi-pi aromatic stacking, and hydrophobic interactions for intermolecular interaction. The amphiphiles are able to self-align into orderly hierarchical assemblies after simply being dissolved in water and dried under spin-coated evaporation. Under the TM-AFM tapping process, the bundles increased their length from an initial 20 to 600 nm. A sequential TM-AFM scanning and interval heating process was designed to probe the morphological transformations from the molecular bundles to lengthy strips (nearly micrometer scale) and to columns (with 5-7 nm spacing between the parallel strips). The formation of hierarchical arrays via molecular stretching, aligning, and connecting to each other was simultaneously observed and accelerated under the TM-AFM vibration energy. The molecular self-alignment caused by vibrations is envisioned to be a potential methodology for manipulating molecules into assembled templates, sensors, and optoelectronic devices.

  1. Thermal degradation kinetics of sucrose palmitate reinforced poly(lactic acid) biocomposites.

    PubMed

    Valapa, Ravibabu; Pugazhenthi, Gopal; Katiyar, Vimal

    2014-04-01

    The current work is focused on investigating the influence of novel bio-filler, "sucrose palmitate (SP)" on the thermal degradation behavior of poly(lactic acid) (PLA) biocomposites in order to render its suitability for food packaging application. Thermal degradation behavior of the PLA biocomposites was investigated by thermo-gravimetric analysis (TGA) using dynamic heating regime. The differential TG analysis revealed that there is no change in the Tmax value (357 °C) for PLA and its composites up to 5 wt% of bio-filler loading. This reveals that the sucrose palmitate acts as a protective barrier by decelerating the thermal degradation rate of PLA. In the case of 10 wt% of the filler incorporated in the PLA matrix, Tmax rapidly shifted to lower temperature (324 °C). This downturn in Tmax at higher loading of the filler is due to the increase in acidic sites and enhancement in the rate of degradation is observed. Differential scanning calorimetry (DSC) analysis revealed unimodal melting peak indicating the α-crystalline form of PLA. Based on the thermal degradation profile of sucrose palmitate, possible mechanism for degradation of PLA composites is proposed. The activation energies (Ea) of thermal degradation of PLA and PLA composites were evaluated by Flynn-Wall-Ozawa and Kissinger methods.

  2. Removal of lead from aqueous solutions by a poly(acrylic acid)/bentonite nanocomposite

    NASA Astrophysics Data System (ADS)

    Rafiei, H. R.; Shirvani, M.; Ogunseitan, O. A.

    2016-11-01

    We synthesized a novel poly acrylic acid-organobentonite (PAA-Bent) nanocomposite by successive intercalation of cetyltrimethylammonium (CTA) surfactant and polyacrylic acid (PAA) into the bentonite (Bent) interlayer spaces. The surfactant-modified clay (CTA-Bent) and PAA-Bent nanocomposite were characterized by XRD and FT-IR techniques and used for removal of Pb(II) from aqueous solution. The XRD results confirmed the intercalation of CTA and PAA into the interlayer spaces of the bentonite increasing the d 001 spacing of the clay from 12.2 up to 38.9 Å. FT-IR analysis of the modified clay samples revealed the functional groups of CTA and PAA constituents alighted on the bentonite surfaces. Maximum Pb sorption capacity of the Bent and PAA-Bent predicted by Langmuir model were 52.3 and 93.0 mg g-1, respectively, showing that the synthesized nanocomposite superiorly adsorbed Pb from the solution as compared to the Bent. The maximum Pb removal efficiency of 99.6 % was achieved by the nanocomposite at 25 °C with <30 min contact time for a 7.5 g L-1 solid-to-liquid ratio and an initial metal concentration of 400 mg L-1. The results indicated that PAA-Bent nanocomposite can be efficiently used as a superadsorbent for the removal of Pb(II) from aqueous solution.

  3. Water vapour permeability of poly(lactic acid): Crystallinity and the tortuous path model

    NASA Astrophysics Data System (ADS)

    Duan, Z.; Thomas, N. L.

    2014-02-01

    The water vapour transmission rates (WVTR) through samples of polylactic acid of different crystallinities have been measured. Three different grades of commercial poly(lactic acid) (PLA) were used with different ratios of L-lactide and D-lactide to give a range of crystallinities from 0% to 50%. Sheets of PLA were prepared by melt compounding followed by compression moulding and annealing at different temperatures and for different times to give the range of crystallinities required. Crystallinity was measured by differential scanning calorimetry and the morphology of the samples was observed under crossed polars in a transmitted light microscope. Water vapour transmission rates through the films were measured at 38 °C and at a relative humidity of 90%. It was found that the measured values of WVTR decreased linearly with increasing crystallinity of the PLA from 0% to 50%. The results are discussed in terms of the effect of crystallinity on solubility and shown to fit the "Tortuous Path Model." The model was also successfully used to explain published data on water permeability of polyethylene terephthalate.

  4. Controlling Internal Organization of Multilayer Poly(methacrylic acid) Hydrogels with Polymer Molecular Weight

    DOE PAGES

    Kozlovskaya, Veronika; Zavgorodnya, Oleksandra; Ankner, John F.; ...

    2015-11-16

    Here, we report on tailoring the internal architecture of multilayer-derived poly(methacrylic acid) (PMAA) hydrogels by controlling the molecular weight of poly(N-vinylpyrrolidone) (PVPON) in hydrogen-bonded (PMAA/PVPON) layer-by-layer precursor films. The hydrogels are produced by cross-linking PMAA in the spin-assisted multilayers followed by PVPON release. We found that the thickness, morphology, and architecture of hydrogen-bonded films and the corresponding hydrogels are significantly affected by PVPON chain length. For all systems, an increase in PVPON molecular weight from Mw = 2.5 to 1300 kDa resulted in increased total film thickness. We also show that increasing polymer Mw smooths the hydrogen-bonded film surfaces butmore » roughens those of the hydrogels. Using deuterated dPMAA marker layers in neutron reflectometry measurements, we found that hydrogen-bonded films reveal a high degree of stratification which is preserved in the cross-linked films. We observed dPMAA to be distributed more widely in the hydrogen-bonded films prepared with small Mw PVPON due to the greater mobility of short-chain PVPON. Furthermore, these variations in the distribution of PMAA are erased after cross-linking, resulting in a distribution of dPMAA over about two bilayers for all Mw but being somewhat more widely distributed in the films templated with higher Mw PVPON. Finally, our results yield new insights into controlling the organization of nanostructured polymer networks using polymer molecular weight and open opportunities for fabrication of thin films with well-organized architecture and controllable function.« less

  5. Controlling Internal Organization of Multilayer Poly(methacrylic acid) Hydrogels with Polymer Molecular Weight

    SciTech Connect

    Kozlovskaya, Veronika; Zavgorodnya, Oleksandra; Ankner, John F.; Kharlampieva, Eugenia

    2015-11-16

    Here, we report on tailoring the internal architecture of multilayer-derived poly(methacrylic acid) (PMAA) hydrogels by controlling the molecular weight of poly(N-vinylpyrrolidone) (PVPON) in hydrogen-bonded (PMAA/PVPON) layer-by-layer precursor films. The hydrogels are produced by cross-linking PMAA in the spin-assisted multilayers followed by PVPON release. We found that the thickness, morphology, and architecture of hydrogen-bonded films and the corresponding hydrogels are significantly affected by PVPON chain length. For all systems, an increase in PVPON molecular weight from Mw = 2.5 to 1300 kDa resulted in increased total film thickness. We also show that increasing polymer Mw smooths the hydrogen-bonded film surfaces but roughens those of the hydrogels. Using deuterated dPMAA marker layers in neutron reflectometry measurements, we found that hydrogen-bonded films reveal a high degree of stratification which is preserved in the cross-linked films. We observed dPMAA to be distributed more widely in the hydrogen-bonded films prepared with small Mw PVPON due to the greater mobility of short-chain PVPON. Furthermore, these variations in the distribution of PMAA are erased after cross-linking, resulting in a distribution of dPMAA over about two bilayers for all Mw but being somewhat more widely distributed in the films templated with higher Mw PVPON. Finally, our results yield new insights into controlling the organization of nanostructured polymer networks using polymer molecular weight and open opportunities for fabrication of thin films with well-organized architecture and controllable function.

  6. A simple sonochemical method for fabricating poly(methyl methacrylate)/stearic acid phase change energy storage nanocapsules.

    PubMed

    Wang, Guxia; Xu, Weibing; Hou, Qian; Guo, Shengwei

    2015-11-01

    In this study, stearic acid suitable for thermal energy storage applications was nanoencapsulated in a poly(methyl methacrylate) shell. The nanocapsules were prepared using a simple ultrasonically initiated in situ polymerization method. The morphology and particle size of the poly(methyl methacrylate)/stearic acid phase change energy storage nanocapsules (PMS-PCESNs) were analyzed using transmission electron microscopy, scanning electron microscopy, atomic force microscopy and dynamic light scattering. The latent heat storage capacities of stearic acid and the PMS-PCESNs were determined using differential scanning calorimetry. The chemical composition of the nanocapsules was characterized using Fourier transform infrared spectroscopy. All of the results show that the PMS-PCESNs were synthesized successfully and that the latent heat storage capacity and encapsulation efficiency were 155.6 J/g and 83.0%, respectively, and the diameter of each nanocapsule was 80-90 nm.

  7. Surface tailoring of poly(DL-lactic acid) by ligand-tethered amphiphilic polymer for promoting chondrocyte attachment and growth.

    PubMed

    Ji, Jian; Zhu, Huiguang; Shen, Jiacong

    2004-05-01

    The ligand-tethered poly(ethylene oxide-propylene oxide-ethylene oxide) (PEO-PPO-PEO) triblock copolymer was explored to engineer poly(DL-lactic acid) (PDL-LA) material to promote cell attachment and growth. The PEO-PPO-PEO was activated by methyl sulfonyl chloride and the amino acid, and peptide were attached. By blending the PDL-LA with the ligand-tethered PEO-PPO-PEO derivatives, the surface of modified PDL-LA film was investigated by ATR-FTIR, XPS and contact angle. The chondrocytes test on different PDL-LA films indicated that the PEO-PPO-PEO amino acid and RGD derivatives modified PDL-LA films could promote chondrocyte attachment and growth. This simple surface treatment method may have potentials for tissue engineering and other biomedical applications.

  8. Preparation of stereoregular isotactic poly(mandelic acid) through organocatalytic ring-opening polymerization of a cyclic O-carboxyanhydride.

    PubMed

    Buchard, Antoine; Carbery, David R; Davidson, Matthew G; Ivanova, Petya K; Jeffery, Ben J; Kociok-Köhn, Gabriele I; Lowe, John P

    2014-12-08

    Poly(mandelic acid) (PMA) is an aryl analogue of poly(lactic acid) (PLA) and a biodegradable analogue of polystyrene. The preparation of stereoregular PMA was realized using a pyridine/mandelic acid adduct (Py⋅MA) as an organocatalyst for the ring-opening polymerization (ROP) of the cyclic O-carboxyanhydride (manOCA). Polymers with a narrow polydispersity index and excellent molecular-weight control were prepared at ambient temperature. These highly isotactic chiral polymers exhibit an enhancement of the glass-transition temperature (T(g)) of 15 °C compared to the racemic polymer, suggesting potential future application as high-performance commodity and biomedical materials.

  9. Glycerine and levulinic acid: renewable co-substrates for the fermentative synthesis of short-chain poly(hydroxyalkanoate) biopolymers.

    PubMed

    Ashby, Richard D; Solaiman, Daniel K Y; Strahan, Gary D; Zhu, Chengjun; Tappel, Ryan C; Nomura, Christopher T

    2012-08-01

    Glycerine (a biodiesel co-product) and levulinic acid (a pulp and paper co-product) were used as co-substrates for the fermentative synthesis of short-chain polyhydroxyalkanoate (sc-PHA) biopolymers with tunable monomer and molecular weight characteristics. Pseudomonas oleovorans NRRL B-14682 utilized glycerine alone to produce poly(3-hydroxybutyrate) (PHB). When levulinic acid was added to the media at shake-flask scale in concentrations ≤0.6 wt.%, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB/V) copolymers were produced with 3-HV contents ranging from 37 to 97 mol%; a glycerine:levulinic acid ratio of 0.2%:0.8% (w/v) resulted in poly(3-hydroxyvalerate) (PHV). Ten-liter batch fermentations using glycerine:levulinic acid ratios of 1%:0, 0.75%:0.25%, 0.5%:0.5% and 0.25%:0.75% (w/v) resulted in PHB, P(73%-3HB-co-27%-3HV), P(30%-3HB-co-70%-3HV) and PHV with increasing number average molecular weights (×10(3) g/mol) of 328, 511, 728 and 1330, respectively, owing to glycerine-based chain termination. These results provide a novel means by which glycerine and levulinic acid can be used collectively to produce an array of distinct sc-PHA biopolymers.

  10. Phosphorus-31 NMR spectra of ethidium, quinacrine, and daunomycin complexes with poly(adenylic acid)ter dot poly(uridylic acid) RNA duplex and calf thymus DNA

    SciTech Connect

    Gorenstein, D.G.; Lai, K. )

    1989-04-04

    {sup 31}P NMR provides a convenient monitor of the phosphate ester backbone conformational changes upon binding of the intercalating drugs ethidium, quinacrine, and daunomycin to sonicated poly(A){center dot}poly(U) and calf thymus DNA. {sup 31}P chemical shifts can also be used to assess differences in the duplex unwinding angles in the presence of the drug. Thus a new {sup 31}P signal, 1.8-2.2 ppm downfield from the double-stranded helix signals, is observed in the ethidium ion-poly(A){center dot}poly(U) complex. This signal arises from phosphates which are in perturbed environments due to intercalation of the drug. This is in keeping with the hypothesis that the P-O ester torsional angle in phosphates linking the intercalated base pairs is more trans-like. Similar though smaller deshielding of the {sup 31}P signals is observed in sonicated poly(A){center dot}poly(U)-quinacrine complexes as well as in the daunomycin complexes. The effect of added ethidium ion, quinacrine, and daunomycin on the {sup 31}P spectra of sonicated calf thymus DNA is consistent with Wilson and Jones' (1982) earlier study. In these drug-DNA complexes the drug produces a gradual downfield shift in the DNA {sup 31}P signal without the appearance of a separate downfield peak. These differences are attributed to differences in the rate of chemical exchange of the drug between free and bound duplex states. The previous correlation of {sup 31}P chemical shift with drug duplex unwinding angle is confirmed for both the RNA and DNA duplexes.

  11. Poly(ester amide)s based on (L)-lactic acid oligomers and α-amino acids: influence of the α-amino acid side chain in the poly(ester amide)s properties.

    PubMed

    Fonseca, Ana C; Coelho, Jorge F J; Valente, Joana F A; Correia, Tiago R; Correia, Ilídio J; Gil, Maria H; Simões, Pedro N

    2013-01-01

    Novel biodegradable and low cytotoxic poly(ester amide)s (PEAs) based on α-amino acids and (L)-lactic acid (L-LA) oligomers were successfully synthesized by interfacial polymerization. The chemical structure of the new polymers was confirmed by spectroscopic analyses. Further characterization suggests that the α-amino acid plays a critical role on the final properties of the PEA. L-phenylalanine provides PEAs with higher glass transition temperature, whereas glycine enhances the crystallinity. The hydrolytic degradation in PBS (pH = 7.4) at 37 °C also depends on the α-amino acid, being faster for glycine-based PEAs. The cytotoxic profiles using fibroblast human cells indicate that the PEAs did not elicit an acute cytotoxic effect. The strategy presented in this work opens the possibility of synthesizing biodegradable PEAs with low citotoxicity by an easy and fast method. It is worth to mention also that the properties of these materials can be fine-tuned only by changing the α-amino acid.

  12. Synthesis, characterization, and morphology study of poly(acrylamide-co-acrylic acid)-grafted-poly(styrene-co-methyl methacrylate) "raspberry"-shape like structure microgels by pre-emulsified semi-batch emulsion polymerization.

    PubMed

    Ramli, Ros Azlinawati; Hashim, Shahrir; Laftah, Waham Ashaier

    2013-02-01

    A novel microgels were polymerized using styrene (St), methyl methacrylate (MMA), acrylamide (AAm), and acrylic acid (AAc) monomers in the presence of N,N'-methylenebisacrylamide (MBA) cross-linker. Pre-emulsified monomer was first prepared followed by polymerizing monomers using semi-batch emulsion polymerization. Fourier Transform Infrared Spectroscopy (FTIR) and (1)H Nuclear Magnetic Resonance (NMR) were used to determine the chemical structure and to indentify the related functional group. Grafting and cross-linking of poly(acrylamide-co-acrilic acid)-grafted-poly(styrene-co-methyl methacrylate) [poly(AAm-co-AAc)-g-poly(St-co-MMA)] microgels are approved by the disappearance of band at 1300 cm(-1), 1200 cm(-1) and 1163 cm(-1) of FTIR spectrum and the appearance of CH peaks at 5.5-5.7 ppm in (1)H NMR spectrum. Scanning Electron Microscope (SEM) images indicated that poly(St-co-MMA) particle was lobed morphology coated by cross-linked poly(AAm-co-AAc) shell. Furthermore, SEM results revealed that poly(AAm-co-AAc)-g-poly(St-co-MMA) is composite particle that consist of "raspberry"-shape like structure core. Internal structures of the microgels showed homogeneous network of pores, an extensive interconnection among pores, thicker pore walls, and open network structures. Water absorbency test indicated that the sample with particle size 0.43 μm had lower equilibrium water content, % than the sample with particle size 7.39 μm.

  13. In vivo toxicity and immunogenicity of wheat germ agglutinin conjugated poly(ethylene glycol)-poly(lactic acid) nanoparticles for intranasal delivery to the brain.

    PubMed

    Liu, Qingfeng; Shao, Xiayan; Chen, Jie; Shen, Yehong; Feng, Chengcheng; Gao, Xiaoling; Zhao, Yue; Li, Jingwei; Zhang, Qizhi; Jiang, Xinguo

    2011-02-15

    Biodegradable polymer-based nanoparticles have been widely studied to deliver therapeutic agents to the brain after intranasal administration. However, knowledge as to the side effects of nanoparticle delivery system to the brain is limited. The aim of this study was to investigate the in vivo toxicity and immunogenicity of wheat germ agglutinin (WGA) conjugated poly(ethylene glycol)-poly(lactic acid) nanoparticles (WGA-NP) after intranasal instillation. Sprague-Dawley rats were intranasally given WGA-NP for 7 continuous days. Amino acid neurotransmitters, lactate dehydrogenase (LDH) activity, reduced glutathione (GSH), acetylcholine, acetylcholinesterase activity, tumor necrosis factor α (TNF-α) and interleukin-8 (IL-8) in rat olfactory bulb (OB) and brain were measured to estimate the in vivo toxicity of WGA-NP. Balb/C mice were intranasally immunized by WGA-NP and then WGA-specific antibodies in serum and nasal wash were detected by indirect ELISA. WGA-NP showed slight toxicity to brain tissue, as evidenced by increased glutamate level in rat brain and enhanced LDH activity in rat OB. No significant changes in acetylcholine level, acetylcholinesterase activity, GSH level, TNF-α level and IL-8 level were observed in rat OB and brain for the WGA-NP group. WGA-specific antibodies in mice serum and nasal wash were not increased after two intranasal immunizations of WGA-NP. These results demonstrate that WGA-NP is a safe carrier system for intranasal delivery of therapeutic agents to the brain.

  14. Economical production of poly(ε-l-lysine) and poly(l-diaminopropionic acid) using cane molasses and hydrolysate of streptomyces cells by Streptomyces albulus PD-1.

    PubMed

    Xia, Jun; Xu, Zhaoxian; Xu, Hong; Liang, Jinfeng; Li, Sha; Feng, Xiaohai

    2014-07-01

    Poly(ε-L-lysine) (ε-PL) and poly(L-diaminopropionic acid) (PDAP) co-production by Streptomyces albulus PD-1 from cane molasses and hydrolysate of strepyomyces cells (HSC) was investigated for the first time in this study. The optimal initial total sugar concentration of the cane molasses pretreated with sulfuric acid was determined to be 20 g L(-1), and HSC could substitute for yeast extract for ε-PL and PDAP co-production. When fed-batch fermentation was performed in 1t fermentor with pretreated cane molasses and HSC, 20.6 ± 0.5 g L(-1) of ε-PL and 5.2 ± 0.6 g L(-1) of PDAP were obtained. The amount of strepyomyces cells obtained in one fed-batch fermentation is sufficient to prepare the HSC to satisfy the demand of subsequent fermentations, thus the self-cycling of organic nitrogen source becomes available. These results suggest that the low-cost cane molasses and HSC can be used for the economical production of ε-PL and PDAP by S. albulus PD-1.

  15. In vivo toxicity and immunogenicity of wheat germ agglutinin conjugated poly(ethylene glycol)-poly(lactic acid) nanoparticles for intranasal delivery to the brain

    SciTech Connect

    Liu Qingfeng; Shao Xiayan; Chen Jie; Shen Yehong; Feng Chengcheng; Gao Xiaoling; Zhao Yue; Li Jingwei; Zhang Qizhi Jiang, Xinguo

    2011-02-15

    Biodegradable polymer-based nanoparticles have been widely studied to deliver therapeutic agents to the brain after intranasal administration. However, knowledge as to the side effects of nanoparticle delivery system to the brain is limited. The aim of this study was to investigate the in vivo toxicity and immunogenicity of wheat germ agglutinin (WGA) conjugated poly(ethylene glycol)-poly(lactic acid) nanoparticles (WGA-NP) after intranasal instillation. Sprague-Dawley rats were intranasally given WGA-NP for 7 continuous days. Amino acid neurotransmitters, lactate dehydrogenase (LDH) activity, reduced glutathione (GSH), acetylcholine, acetylcholinesterase activity, tumor necrosis factor {alpha} (TNF-{alpha}) and interleukin-8 (IL-8) in rat olfactory bulb (OB) and brain were measured to estimate the in vivo toxicity of WGA-NP. Balb/C mice were intranasally immunized by WGA-NP and then WGA-specific antibodies in serum and nasal wash were detected by indirect ELISA. WGA-NP showed slight toxicity to brain tissue, as evidenced by increased glutamate level in rat brain and enhanced LDH activity in rat OB. No significant changes in acetylcholine level, acetylcholinesterase activity, GSH level, TNF-{alpha} level and IL-8 level were observed in rat OB and brain for the WGA-NP group. WGA-specific antibodies in mice serum and nasal wash were not increased after two intranasal immunizations of WGA-NP. These results demonstrate that WGA-NP is a safe carrier system for intranasal delivery of therapeutic agents to the brain.

  16. Opsonisation of nanoparticles prepared from poly(β-hydroxybutyrate) and poly(trimethylene carbonate)-b-poly(malic acid) amphiphilic diblock copolymers: Impact on the in vitro cell uptake by primary human macrophages and HepaRG hepatoma cells.

    PubMed

    Vene, Elise; Barouti, Ghislaine; Jarnouen, Kathleen; Gicquel, Thomas; Rauch, Claudine; Ribault, Catherine; Guillaume, Sophie M; Cammas-Marion, Sandrine; Loyer, Pascal

    2016-11-20

    The present work reports the investigation of the biocompatibility, opsonisation and cell uptake by human primary macrophages and HepaRG cells of nanoparticles (NPs) formulated from poly(β-malic acid)-b-poly(β-hydroxybutyrate) (PMLA-b-PHB) and poly(β-malic acid)-b-poly(trimethylene carbonate) (PMLA-b-PTMC) diblock copolymers, namely PMLA800-b-PHB7300, PMLA4500-b-PHB4400, PMLA2500-b-PTMC2800 and PMLA4300-b-PTMC1400. NPs derived from PMLA-b-PHB and PMLA-b-PTMC do not trigger lactate dehydrogenase release and do not activate the secretion of pro-inflammatory cytokines demonstrating the excellent biocompatibility of these copolymers derived nano-objects. Using a protein adsorption assay, we demonstrate that the binding of plasma proteins is very low for PMLA-b-PHB-based nano-objects, and higher for those prepared from PMLA-b-PTMC copolymers. Moreover, a more efficient uptake by macrophages and HepaRG cells is observed for NPs formulated from PMLA-b-PHB copolymers compared to that of PMLA-b-PTMC-based NPs. Interestingly, the uptake in HepaRG cells of NPs formulated from PMLA800-b-PHB7300 is much higher than that of NPs based on PMLA4500-b-PHB4400. In addition, the cell internalization of PMLA800-b-PHB7300 based-NPs, probably through endocytosis, is strongly increased by serum pre-coating in HepaRG cells but not in macrophages. Together, these data strongly suggest that the binding of a specific subset of plasmatic proteins onto the PMLA800-b-PHB7300-based NPs favors the HepaRG cell uptake while reducing that of macrophages.

  17. Functional Properties and Biodistribution of poly(triethylenetetramine/cystamine bisacrylamide) and poly(triethylenetetramine/cystamine bisacrylamide)- poly(ethylene glycol) mixtures formed with nucleic acid

    PubMed Central

    Brumbach, Jonathan H.; Lee, Yong Won; Kim, Sung Wan; Yockman, James

    2012-01-01

    The clinical success of non-viral gene delivery reagents is hampered by their inefficient cellular transgene delivery, which is largely influenced by carrier properties that are currently undefined and misunderstood. In an attempt to further define and understand the requirements for a safe and efficient non-viral gene delivery reagent, research labs often engineer and evaluate many putative products with subtle physiochemical differences in order to delineate requirements for improved in vitro and in vivo success. The synthesis of many putative reagents is often time-intensive, laborious and costly. In a previous manuscript published by our lab, different amounts of poly(triethylenetetramine/cystamine bisacrylamide) (p(TETA/CBA) and its pegylated counterpart, poly(triethylenetetramine/cystamine bisacrylamide)- poly(ethylene glycol) (p(TETA/CBA)-g-PEG) were mixed together to easily identify optimal reagent properties and candidates in vitro, while avoiding the synthesis of many putative candidates for study. This report uses the aforementioned facile approach to evaluate reagent properties of products that were obtained via one-pot synthesis, which improved synthetic ease. As such, synthesis time was reduced from 6 days to 3 days and had comparable or improved transfection and viability compared to previous works. Moreover, this synthesis resulted in higher molecular weight products than were used in the previous study and allow for lower polymer doses to be used for complexation, which is useful for systemic delivery that is used herein. The physiochemical properties of the formulations derived using these novel reagents was studied prior to investigating their in vivo biodistribution profiles in a murine colon adenocarcinoma model. Interestingly, negatively charged complexes exhibited greater passive tumor accumulation compared to positively charged complexes following their systemic administration. These studies warrant further investigation for the use of

  18. The influence of using vacuum-dried poly(alkenoic) acids upon the physical properties of a glass polyalkenoate (ionomer) cement.

    PubMed

    Walls, A W; McCabe, J F; Murray, J J

    1989-06-01

    Some of the physical characteristics of two glass polyalkenoate cements have been measured. The two cements differ in terms of the presentation of the poly(alkenoic) acid used to form the cement and in the method of mixing of the materials. The 'conventional' cement uses an aqueous solution of poly(acid) and is an encapsulated mechanically mixed material. The alternative material contains a vacuum-dried poly(acid) powder with the ion-leachable glass, and is mixed by hand with a 15 per cent aqueous solution of tartaric acid. There were some minor differences between the two products, including a delay in the onset of the setting reaction for the material containing the vacuum-dried poly(acid) powder. These differences would probably have little significant effect upon the clinical performance of the materials.

  19. Radiation Synthesis of Poly(Starch/Acrylic acid) pH Sensitive Hydrogel for Rutin Controlled Release.

    PubMed

    Abdel Ghaffar, A M; Radwan, Rasha R; Ali, H E

    2016-11-01

    The copolymerization of starch with acrylic acid AAc using direct gamma radiation technique was performed. The effect of AAc concentrations on the gel (%) and swelling behavior were investigated. It is found that as AAc concentrations increase both gel(%) and swelling behavior increase. The Poly(starch/acrylic acid) (1:10wt%) hydrogel were selected due to its high swelling properties. From the in-vitro release study of the rutin-loaded hydrogel it is observed that it is strong pH-dependent release behavior, thus offering a maximum release as pH increased. The dextran sulphate sodium (DSS)-induced rat colitis model was treated with rutin-loaded Poly(starch/acrylic acid) (1:10wt%) hydrogel and free rutin solution by oral administration. Colitic control group showed a significant elevation in colon/body weight ratio, myeloperoxgidase activity, tumor necrosis factor, nitric oxide and malondialdehyde levels. However, glutathione level was reduced. It was found that the rutin-loaded hydrogel was more efficient than free rutin as evidenced by improvement of all measured parameters. These effects were confirmed histopathologically and may be attributed to its ability to control delivery of rutin to colon with minor early release of rutin before colon. The Poly(starch/acrylic acid) (1:10wt%) can represent a pivotal anti-inflammatory approach for patients with inflammatory bowel disease in order to increase efficacy and reduce toxicity.

  20. Self-assemblies of pH-activatable PEGylated multiarm poly(lactic acid-co-glycolic acid)-doxorubicin prodrugs with improved long-term antitumor efficacies.

    PubMed

    Ding, Jianxun; Li, Di; Zhuang, Xiuli; Chen, Xuesi

    2013-10-01

    Two pH-activatable star-shaped prodrugs are synthesized through the condensation reaction between Y- or dumbbell-shaped poly(ethylene glycol)-poly(lactic acid-co-glycolic acid) (PEG-PLGA) copolymer and acid-sensitive cis-aconityl-doxorubicin. The prodrugs self-assemble into micelles with favorable hydrodynamic radii and relatively low critical micelle concentrations. In vitro DOX release from prodrug micelles is accelerated by the decrease of the PLGA content or at the late endosomal pH. The efficient cellular uptake and intracellular DOX release of the prodrug micelles are confirmed and the improved long-term anti-proliferative activities of prodrug micelles are revealed. These features suggest that the prodrugs provide a favorable approach to construct effective polymeric drug delivery systems for malignancy therapy.

  1. All-trans retinoic acid with daunorubicin or idarubicin for risk-adapted treatment of acute promyelocytic leukaemia: a matched-pair analysis of the PETHEMA LPA-2005 and IC-APL studies.

    PubMed

    Sanz, Miguel A; Montesinos, Pau; Kim, Haesook T; Ruiz-Argüelles, Guillermo J; Undurraga, María S; Uriarte, María R; Martínez, Lem; Jacomo, Rafael H; Gutiérrez-Aguirre, Homero; Melo, Raul A M; Bittencourt, Rosane; Pasquini, Ricardo; Pagnano, Katia; Fagundes, Evandro M; Vellenga, Edo; Holowiecka, Alexandra; González-Huerta, Ana J; Fernández, Pascual; De la Serna, Javier; Brunet, Salut; De Lisa, Elena; González-Campos, José; Ribera, José M; Krsnik, Isabel; Ganser, Arnold; Berliner, Nancy; Ribeiro, Raul C; Lo-Coco, Francesco; Löwenberg, Bob; Rego, Eduardo M

    2015-08-01

    Front-line treatment of acute promyelocytic leukaemia (APL) consists of all-trans retinoic acid (ATRA) and anthracycline-based chemotherapy. In this setting, a comparison of idarubicin and daunorubicin has never been carried out. Two similar clinical trials using ATRA and chemotherapy for newly diagnosed APL were compared using matched-pair analysis. One was conducted by the PETHEMA/HOVON group with idarubicin and the other by the International Consortium on APL (IC-APL) using daunorubicin. Three hundred and fifty patients from the PETHEMA/HOVON cohort were matched with 175 patients in the IC-APL cohort, adjusting for the significantly unbalanced presenting features of the two entire cohorts. Complete remission (CR) rate was significantly higher in the PETHEMA/HOVON (94 %) than in the IC-APL cohort (85 %) (P = 0.002). The distribution of causes of induction failure and the time to achieve CR were similar in both cohorts. Patients who achieved CR had comparable cumulative incidence of relapse and disease-free survival rates, but lower overall and event-free survivals were observed in the IC-APL cohort, which was mainly due to a higher death rate during induction therapy. A higher death rate during consolidation therapy was also observed in the IC-APL. These results show that daunorubicin and idarubicin have similar antileukaemic efficacy in terms of primary resistance, molecular persistence, as well as molecular and haematological relapse rates when combined with ATRA in treatment of APL. However, a higher toxic death rate during induction and consolidation therapy was observed in the IC-APL cohort. This trial was registered at www.clinicaltrials.gov as #NCT00408278 [ClinicalTrials.gov].

  2. Controlled release of drug and better bioavailability using poly(lactic acid-co-glycolic acid) nanoparticles.

    PubMed

    Pandey, Sanjeev K; Patel, Dinesh K; Maurya, Akhilendra K; Thakur, Ravi; Mishra, Durga P; Vinayak, Manjula; Haldar, Chandana; Maiti, Pralay

    2016-08-01

    Tamoxifen (Tmx) embedded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (PLGA-Tmx) is prepared to evaluate its better DNA cleavage potential, cytotoxicity using Dalton's lymphoma ascite (DLA) cells and MDA-MB231 breast cancer cells. PLGA-Tmx nanoparticles are prepared through emulsified nanoprecipitation technique with varying dimension of 17-30nm by changing the concentrations of polymer, emulsifier and drug. Nanoparticles dimension are measured through electron and atomic force microscopy. Interactions between tamoxifen and PLGA are verified through spectroscopic and calorimetric methods. PLGA-Tmx shows excellent DNA cleavage potential as compared to pure Tmx raising better bioavailability. In vitro cytotoxicity studies indicate that PLGA-Tmx reduces DLA cells viability up to ∼38% against ∼15% in pure Tmx. Hoechst stain is used to detect apoptotic DLA cells through fluorescence imaging of nuclear fragmentation and condensation exhibiting significant increase of apoptosis (70%) in PLGA-Tmx vis-à-vis pure drug (58%). Enhanced DNA cleavage potential, nuclear fragmentation and condensation in apoptotic cells confirm greater bioavailability of PLGA-Tmx as compared to pure Tmx in terms of receptor mediated endocytosis. Hence, the sustained release kinetics of PLGA-Tmx nanoparticles shows much better anticancer efficacy through enhanced DNA cleavage potential and nuclear fragmentation and, thereby, reveal a novel vehicle for the treatment of cancer.

  3. Hyaluronic acid-decorated poly(lactic-co-glycolic acid) nanoparticles for combined delivery of docetaxel and tanespimycin.

    PubMed

    Pradhan, Roshan; Ramasamy, Thiruganesh; Choi, Ju Yeon; Kim, Jeong Hwan; Poudel, Bijay Kumar; Tak, Jin Wook; Nukolova, Natalia; Choi, Han-Gon; Yong, Chul Soon; Kim, Jong Oh

    2015-06-05

    Multiple-drug combination therapy is becoming more common in the treatment of advanced cancers because this approach can decrease side effects and delay or prevent drug resistance. In the present study, we developed hyaluronic acid (HA)-decorated poly(lactic-co-glycolic acid) (PLGA) nanoparticles (HA-PLGA NPs) for co-delivery of docetaxel (DTX) and tanespimycin (17-AAG). DTX and 17-AAG were simultaneously loaded into HA-PLGA NPs using an oil-in-water emulsification/solvent evaporation method. Several formulations were tested. HA-PLGA NPs loaded with DTX and 17-AAG at a molar ratio of 2:1 produced the smallest particle size (173.3±2.2nm), polydispersity index (0.151±0.026), and zeta potential (-12.4±0.4mV). Approximately 60% and 40% of DTX and 17-AAG, respectively, were released over 168h in vitro. Cytotoxicity assays performed in vitro using MCF-7, MDA-MB-231, and SCC-7 cells showed that dual drug-loaded HA-PLGA NPs at a DTX:17-AAG molar ratio of 2:1 exhibited the highest synergistic effect, with combination index values of 0.051, 0.036, and 0.032, respectively, at the median effective dose. Furthermore, synergistic antitumor activity was demonstrated in vivo in a CD44 and RHAMM (CD168) - overexpressing squamous cell carcinoma (SCC-7) xenograft in nude mice. These findings indicated that nanosystem-based co-delivery of DTX and 17-AAG could provide a promising combined therapeutic strategy for enhanced antitumor therapy.

  4. Development of a solid-phase extraction method for simultaneous extraction of adipic acid, succinic acid and 1,4-butanediol formed during hydrolysis of poly(butylene adipate) and poly(butylene succinate).

    PubMed

    Lindström, Annika; Albertsson, Ann-Christine; Hakkarainen, Minna

    2004-01-02

    A solid-phase extraction (SPE) method was developed for the simultaneous extraction of dicarboxylic acids and diols formed during hydrolysis of poly(butylene succinate), PBS, and poly(butylene adipate), PBA. Four commercial non-polar SPE columns, three silica based: C8, C18, C18 (EC), and one resin based: ENV+, were tested for the extraction of succinic acid, adipic acid and 1,4-butanediol, the expected final hydrolysis products of PBS and PBA. ENV+ resin was chosen as a solid-phase, because it displayed the best extraction efficiency for 1,4-butanediol and succinic acid. Linear range for the extracted analytes was 1-500 ng/microl for adipic acid and 2-500 ng/microl for 1,4-butanediol and succinic acid. Detection and quantification limits for the analytes were between 1-2 and 2-7 ng/microl, respectively, and relative standard deviations were between 3 and 7%. Good repeatability and low detection limits made the developed SPE method and subsequent gas chromatography-mass spectrometry (GC-MS) analysis a sensitive tool for identification and quantification of hydrolysis products at early stages of degradation.

  5. Conducting polymer films fabricated by oxidative graft copolymerization of aniline on poly(acrylic acid) grafted poly(ethylene terephthalate) surfaces.

    PubMed

    Wang, Jiku; Liu, Xuyan; Choi, Ho-Suk; Kim, Jong-Hoon

    2008-11-27

    A conductive polyaniline/poly(ethylene terephthalate) (PANI/PET) composite film was fabricated via the oxidative graft copolymerization of aniline (ANI) onto the plasma-induced poly(acrylic acid) (PAAc) grafted PET surface. The attenuated total reflectance Fourier transform infrared spectroscopy spectra (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) results confirmed that PANI was successfully grafted onto the surface of the PAAc-g-PET films. The effects of the experimental conditions on the percentage of PANI grafted onto the PAAc-g-PET films were extensively investigated. A very high grafting percentage of ANI can be obtained through the acid-base reaction between the aniline monomer and PAAc on the PAAc-g-PET surface at high temperature. As a result, the grafting percentage of PANI can be increased to as high as 12.18 wt %, which causes the surface resistance of the PANI-g-PAAc-g-PET film to be reduced to about 1000 Omega/sq. We predicted that this is because of the high flexibility of the PAAc molecular chains and high solubility of aniline, both of which facilitate the binding of aniline to PAAc during this high temperature acid-base reaction. It was observed by atomic force microscopy (AFM) that the PANI-modified PET surface exhibits higher size irregularity and surface roughness, which further indicated that a much greater number of aniline molecules can be reactively bonded to and distributed along the grafted AAc chains and that the PANI-g-PAAc-g-PET surface resulting from the sequential oxidative graft copolymerization can possess higher electrical conductivity.

  6. Control of Alginate Core Size in Alginate-Poly (Lactic-Co-Glycolic) Acid Microparticles

    NASA Astrophysics Data System (ADS)

    Lio, Daniel; Yeo, David; Xu, Chenjie

    2016-01-01

    Core-shell alginate-poly (lactic-co-glycolic) acid (PLGA) microparticles are potential candidates to improve hydrophilic drug loading while facilitating controlled release. This report studies the influence of the alginate core size on the drug release profile of alginate-PLGA microparticles and its size. Microparticles are synthesized through double-emulsion fabrication via a concurrent ionotropic gelation and solvent extraction. The size of alginate core ranges from approximately 10, 50, to 100 μm when the emulsification method at the first step is homogenization, vortexing, or magnetic stirring, respectively. The second step emulsification for all three conditions is performed with magnetic stirring. Interestingly, although the alginate core has different sizes, alginate-PLGA microparticle diameter does not change. However, drug release profiles are dramatically different for microparticles comprising different-sized alginate cores. Specifically, taking calcein as a model drug, microparticles containing the smallest alginate core (10 μm) show the slowest release over a period of 26 days with burst release less than 1 %.

  7. Weathering and Biodegradation Study on Graft Copolymer Compatibilized Hybrid Bionanocomposites of Poly(Lactic Acid)

    NASA Astrophysics Data System (ADS)

    Sajna, VP; Nayak, Sanjay K.; Mohanty, Smita

    2016-07-01

    This work reports on the influence of moisture absorption and accelerated weathering on the properties of graft copolymer compatibilized bionanocomposites of poly(lactic acid) (PLA). Moisture absorption tests were conducted for 30 days by immersing the samples in a distilled water bath at room temperature, and the amount of moisture absorbed in each time interval was measured. The rate of moisture uptake decreased by incorporation of C30B nanoclay and graft copolymer into fiber-reinforced PLA composites. Changes in the mechanical properties of composites in each time interval of moisture absorption were investigated using tensile and impact tests. Exposure to moisture caused significant drops in the mechanical properties. The morphological characterization of biocomposites during the aforementioned tests has been made using SEM, while bionanocomposites were analyzed by TEM. Further, this paper also reported the effect of accelerated weathering on the mechanical properties and the results are confirmed through SEM analysis. Biodegradation behaviors of PLA biocomposites and bionanocomposites have also been studied.

  8. Preparation of hydroxyapatite/poly(lactic acid) hybrid microparticles for local drug delivery

    NASA Astrophysics Data System (ADS)

    Loca, D.; Locs, J.; Berzina-Cimdina, L.

    2013-12-01

    Calcium phosphate (CaP) bioceramic is well known as bioactive and biocompatible material in bone tissue regeneration applications. Apatitic CaP, especially nano sized hydroxyapatite (NHAp), is more similar to the natural apatite presented in the bone tissue than CaP bioceramics. In the current research NHAp was modified using biodegradable polymer - poly(lactic acid) (PLA) to develop composites providing bone regeneration and local drug delivery. NHAp/PLA microcapsules were prepared using solid-in-water-in-oil-in-water (s/w1/o/w2) encapsulation technology. The impact of primary and secondary emulsion stability on the emulsion droplet and microparticle properties was evaluated. The stability of final emulsion can be increased by varying the process parameters. Stable s/w1/o/w2 emulsion using 3ml of NHAp suspension, not less than 100ml of 4% PVA water solution and 10ml of 10% PLA solution in dichloromethane can be obtained. S/w1/o/w2 microencapuslation method can be effectively used for the preparation of multi-domain microcapsules achieving high NHAp encapsulation efficacy (93%).

  9. Lewis acid/base character and crystallisation properties of poly(butylene terephthalate).

    PubMed

    Santos, José M R C A; Guthrie, James T

    2015-01-30

    Two grades of poly(butylene terephthalate) were analysed by means of inverse gas chromatography (IGC) and the results correlated with the respective crystallisation properties. The following parameters were determined by IGC: the dispersive component of the surface tension, the enthalpy and the entropy of adsorption of selected polar and apolar probes, and the Lewis acidity and basicity constants, Ka and Kb respectively. The interpretation of the values determined for Ka and Kb is in agreement with the FTIR spectra relating to the carboxyl end-group and the hydroxyl end-group concentrations in these polymers. The differences in the molecular weight values and in the end-group type and concentration, between the two grades of PBT, do not cause differences in the crystallisation activation energy. This observation suggests that there is a leading contribution of the Lewis basic sites to the crystallisation activation energy of the grades of PBT that were analysed. However, the lower value of Ka and the greater molar mass of one of the PBT grades lead to a corresponding lower crystallisation degree.

  10. Poly(acrylic acid) brushes pattern as a 3D functional biosensor surface for microchips

    NASA Astrophysics Data System (ADS)

    Wang, Yan-Mei; Cui, Yi; Cheng, Zhi-Qiang; Song, Lu-Sheng; Wang, Zhi-You; Han, Bao-Hang; Zhu, Jin-Song

    2013-02-01

    Poly(acrylic acid) (PAA) brushes, a novel three dimensional (3D) precursor layer of biosensor or protein microarrays, possess high protein loading level and low non-specific protein adsorption. In this article, we describe a simple and convenient way to fabricate 3D PAA brushes pattern by microcontact printing (μCP) and characterize it with FT-IR and optical microscopy. The carboxyl groups of PAA brushes can be applied to covalently immobilize protein for immunoassay. Thriving 3D space made by patterning PAA brushes thin film is available to enhance protein immobilization, which is confirmed by measuring model protein interaction between human immunoglobulin G (H-IgG) and goat anti-H-IgG (G-H-IgG) with fluorescence microscopy and surface plasmon resonance imaging (SPRi). As expected, the SPRi signals of H-IgG coating on 3D PAA brushes pattern and further measuring specific binding with G-H-IgG are all larger than that of 3D PAA brushes without pattern and 2D bare gold surface. We further revealed that this surface can be used for high-throughput screening and clinical diagnosis by label-free assaying of Hepatitis-B-Virus surface antibody (HBsAb) with Hepatitis-B-Virus surface antigen (HBsAg) concentration array chip. The linearity range for HBsAb assay is wider than that of conventional ELISA method.

  11. Fabrication of poly (L-lactic acid)/gelatin composite tubular scaffolds for vascular tissue engineering.

    PubMed

    Shalumon, K T; Deepthi, S; Anupama, M S; Nair, S V; Jayakumar, R; Chennazhi, K P

    2015-01-01

    The in vitro fabrication of fully functional 3D vascular tissue construct represents one of the most fundamental challenges in vascular tissue engineering. Polymer blending is an effective method for developing, desirable bio-composites for tissue engineering. This study employs the blending of desired characteristics of a synthetic polymer, poly (L-lactic acid) (PLLA) and a biopolymer, gelatin for enhancing cell adhesion sites. Aligned and random PLLA/gelatin nanofibers were fabricated using electrospinning technique. Morphological and chemical characterization of the nanofibrous scaffolds was carried out and the size of fibers ranged from 100 to 500 nm. The SEM, fluorescent staining and viability assays revealed an increase in viability and proliferation of Human Umbilical Vein Endothelial Cells (HUVECs) and Smooth Muscle Cells (SMCs) proportional to gelatin content. The aligned fiber morphology helps cells to orient and elongate along their long axis. Thus the results were suggestive of the fact that topographically aligned nanofibrous scaffolds control cellular organization and possibly provide a good support for achieving the vital organization and physical properties of blood vessel.

  12. A collagen-poly(lactic acid-co-ɛ-caprolactone) hybrid scaffold for bladder tissue regeneration.

    PubMed

    Engelhardt, Eva-Maria; Micol, Lionel A; Houis, Stephanie; Wurm, Florian M; Hilborn, Jöns; Hubbell, Jeffrey A; Frey, Peter

    2011-06-01

    Scaffold materials should favor cell attachment and proliferation, and provide designable 3D structures with appropriate mechanical strength. Collagen matrices have proven to be beneficial scaffolds for tissue regeneration. However, apart from small intestinal submucosa, they offer a limited mechanical strength even if crosslinking can enhance their mechanical properties. A more cell-friendly way to increase material strength is to combine synthetic polymer meshes with plastic compressed collagen gels. This work describes the potential of plastic compressed collagen-poly(lactic acid-co-ɛ-caprolactone) (PLAC) hybrids as scaffolds for bladder tissue regeneration. Human bladder smooth muscle and urothelial cells were cultured on and inside collagen-PLAC hybrids in vitro. Scaffolds were analyzed by electron microscopy, histology, immunohistochemistry, and AlamarBlue assay. Both cell types proliferated in and on the hybrid, forming dense cell layers on top after two weeks. Furthermore, hybrids were implanted subcutaneously in the backs of nude mice. Host cell infiltration, scaffold degradation, and the presence of the seeded bladder cells were analyzed. Hybrids showed a lower inflammatory reaction in vivo than PLAC meshes alone, and first signs of polymer degradation were visible at six months. Collagen-PLAC hybrids have potential for bladder tissue regeneration, as they show efficient cell seeding, proliferation, and good mechanical properties.

  13. Antimicrobial Poly(lactic acid)-Based Nanofibres Developed by Solution Blow Spinning.

    PubMed

    Martínez-Sanz, Marta; Bilbao-Sainz, Cristina; Du, Wen-Xian; Chiou, Bor-Sen; Williams, Tina G; Wood, Delilah F; Imam, Syed H; Orts, William J; Lopez-Rubio, Amparo; Lagaron, Jose M

    2015-01-01

    The present study reports on the development of hybrid poly(lactic acid) (PLA) fibres loaded with highly crystalline bacterial cellulose nanowhiskers (BCNW) by the novel solution blow spinning method. Furthermore, fibres with antimicrobial properties were generated by incorporating carvacrol and THC as antimicrobial agents and the biocide effect against Listeria monocytogenes was studied. Initially, PLA blow spun fibres containing BCNW were optimized in terms of morphology and thermal properties. The addition of BCNW was seen to significantly increase the viscosity and surface tension of solutions, restricting the capacity to form fibres for concentrations greater than 30 wt.-% BCNW. 15 wt.-% BCNW was selected as the optimum nanofiller loading as it led to the most uniform fibres morphology, with BCNW homogeneously distributed along the fibres' axis. Subsequently, carvacrol and THC were incorporated into the fibres to confer them with antimicrobial properties, although the hydrophobic PLA matrix did not provide an efficient release of the antimicrobials. Thus, hydrophilic substances were added in order to trigger the antimicrobials release through water sorption mechanisms. The addition of the BCNW filler was not seen to significantly increase the antimicrobial capacity of the fibres by itself and, hence, gelatin was added to help promoting further the hydrophylicity and biocide performance of the fibres. Nevertheless, for the more hydrophilic THC, the biocide capacity of the fibres with gelatin was accentuated further by the presence of the BCNW.

  14. Morphological control of calcium oxalate particles in the presence of poly-(styrene-alt-maleic acid)

    NASA Astrophysics Data System (ADS)

    Yu, Jiaguo; Tang, Hua; Cheng, Bei; Zhao, Xiujian

    2004-10-01

    Calcium oxalate (CaOx) particles exhibiting different shapes and phase structures were fabricated by a simple precipitation reaction of sodium oxalate with calcium chloride in the absence and presence of poly-(styrene-alt-maleic acid) (PSMA) as a crystal modifier at room temperature. The as-obtained products were characterized with scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of reaction conditions including pH, [Ca2+]/[C2O42-] ratio and concentration of PSMA and CaC2O4 on the crystal forms and morphologies of the as-obtained calcium oxalate were investigated. The results show that various crystal morphologies of calcium oxalate, such as parallelograms, plates, spheres, bipyramids etc. can be obtained depending on the experimental conditions. Higher polymer concentration favors formation of the metastable calcium oxalate dihydrate (COD) crystals. Lower pH is beneficial to the formation of plate-like CaOx crystals. Especially, the monodispersed parallelogram-like CaOx crystals can be produced by PSMA as an additive at pH 2. PSMA may act as a good inhibitor for urolithiasis since it induces the formation of COD and reduces the particle size of CaOx. This research may provide new insight into the morphological control of CaOx particles and the prevention of urolithiasis.

  15. Bioactivity and cytocompatibility of dicalcium phosphate/poly (amino acid) biocomposite with degradability

    NASA Astrophysics Data System (ADS)

    Zhang, Yunfei; Shan, Wenpeng; Li, Xiangde; Wei, Jie; Li, Hong; Ma, Jian; Yan, Yonggang

    2012-01-01

    A bioactive composite of dicalcium phosphate (DCP) and poly (amino acid) (PAA) was fabricated, and the in vitro bioactivity, degradability, and cellular responses to the DCP/PAA composite (DPC) were investigated as compared to PAA. Apatite formation on DPC surfaces occurred after immersion into simulated body fluid (SBF) for 7 days, but not on the surface of PAA. The weight loss ratio of DPC could reach 18.6 ± 0.3 wt% after soaking into phosphate buffered saline (PBS) for 2 months, which was higher than PAA (11.0 ± 0.2 wt%). Cell attachment and proliferation of MG-63 cells on DPC was obviously higher than on PAA. Moreover, the cells spread and formed confluent layer on the DPC surfaces. The alkaline phosphatase activity (ALP) of the cells on DPC was significantly greater than PAA at day 5 and day 7. The results suggested that introducing DCP into PAA makes the composite bioactive and more degradable, and meanwhile enhances osteoblast-like cells attach, proliferation and osteogenic differentiation.

  16. Identification of important abiotic and biotic factors in the biodegradation of poly(l-lactic acid).

    PubMed

    Husárová, Lucie; Pekařová, Silvie; Stloukal, Petr; Kucharzcyk, Pavel; Verney, Vincent; Commereuc, Sophie; Ramone, Audrey; Koutny, Marek

    2014-11-01

    The biodegradation of four poly(l-lactic acid) (PLA) samples with molecular weights (MW) ranging from approximately 34 to 160kgmol(-1) was investigated under composting conditions. The biodegradation rate decreased, and initial retardation was discernible in parallel with the increasing MW of the polymer. Furthermore, the specific surface area of the polymer sample was identified as the important factor accelerating biodegradation. Microbial community compositions and dynamics during the biodegradation of different PLA were monitored by temperature gradient gel electrophoresis, and were found to be virtually identical for all PLA materials and independent of MW. A specific PLA degrading bacteria was isolated and tentatively designated Thermopolyspora flexuosa FTPLA. The addition of a limited amount of low MW PLA did not accelerate the biodegradation of high MW PLA, suggesting that the process is not limited to the number of specific degraders and/or the induction of specific enzymes. In parallel, abiotic hydrolysis was investigated for the same set of samples and their courses found to be quasi-identical with the biodegradation of all four PLA samples investigated. This suggests that the abiotic hydrolysis represented a rate limiting step in the biodegradation process and the organisms present were not able to accelerate depolymerization significantly by the action of their enzymes.

  17. Poly(lactic acid) filled with cassava starch-g-soybean oil maleate.

    PubMed

    Kiangkitiwan, Nopparut; Srikulkit, Kawee

    2013-01-01

    Poly(lactic acid), PLA, is a biodegradable polymer, but its applications are limited by its high cost and relatively poorer properties when compared to petroleum-based plastics. The addition of starch powder into PLA is one of the most promising efforts because starch is an abundant and cheap biopolymer. However, the challenge is the major problem associated with poor interfacial adhesion between the hydrophilic starch granules and the hydrophobic PLA, leading to poorer mechanical properties. In this paper, soybean oil maleate (SOMA) was synthesized by grafting soybean oil with various weight percents of maleic anhydride (MA) using dicumyl peroxide (DCP) as an initiator. Then, SOMA was employed for the surface modifying of cassava starch powder, resulting in SOMA-g-STARCH. The obtained SOMA-g-STARCH was mixed with PLA in various weight ratios using twin-screw extruder, resulting in PLA/SOMA-g-STARCH. Finally, the obtained PLA/SOMA-g-STARCH composites were prepared by a compression molding machines. The compatibility, thermal properties, morphology properties, and mechanical properties were characterized and evaluated. The results showed that the compatibility, surface appearance, and mechanical properties at 90 : 10 and 80 : 20 ratios of PLA/SOMA-g-STARCH were the best.

  18. Nanomechanical properties of poly(lactic-co-glycolic) acid film during degradation.

    PubMed

    Shirazi, Reyhaneh Neghabat; Aldabbagh, Fawaz; Erxleben, Andrea; Rochev, Yury; McHugh, Peter

    2014-11-01

    Despite the potential applications of poly(lactic-co-glycolic) acid (PLGA) coatings in medical devices, the mechanical properties of this material during degradation are poorly understood. In the present work, the nanomechanical properties and degradation of PLGA film were investigated. Hydrolysis of solvent-cast PLGA film was studied in buffer solution at 37 °C. The mass loss, water uptake, molecular weight, crystallinity and surface morphology of the film were tracked during degradation over 20 days. Characterization of the surface hardness and Young's modulus was performed using the nanoindentation technique for different indentation loads. The initially amorphous films were found to remain amorphous during degradation. The molecular weight of the film decreased quickly during the initial days of degradation. Diffusion of water into the film resulted in a reduction in surface hardness during the first few days, followed by an increase that was due to the surface roughness. There was a significant delay between the decrease in the mechanical properties of the film and the decrease in the molecular weight. A sudden decline in mechanical properties indicated that significant bulk degradation had occurred.

  19. Increased osteoblast functions on nanophase titania dispersed in poly-lactic-co-glycolic acid composites

    NASA Astrophysics Data System (ADS)

    Liu, Huinan; Slamovich, Elliott B.; Webster, Thomas J.

    2005-07-01

    The design of nanophase titania/poly-lactic-co-glycolic acid (PLGA) composites offers an exciting approach to combine the advantages of a degradable polymer with nano-size ceramic grains to optimize physical and biological properties for bone regeneration. Importantly, nanophase titania mimics the size scale of constituent components of bone since it is a nanostructured composite composed of nanometre dimensioned hydroxyapatite well dispersed in a mostly collagen matrix. For these reasons, the objective of the present in vitro study was to investigate osteoblast (bone-forming cell) adhesion and long-term functions on nanophase titania/PLGA composites. Since nanophase titania tended to significantly agglomerate when added to polymers, different sonication output powers were applied in this study to improve titania dispersion. Results demonstrated that the dispersion of titania in PLGA was enhanced by increasing the intensity of sonication and that greater osteoblast adhesion correlated with improved nanophase titania dispersion in PLGA. Moreover, results correlated better osteoblast long-term functions, such as alkaline phosphatase activity and calcium-containing mineral deposition, on nanophase titania/PLGA composites compared to plain PLGA. In fact, the greatest collagen production by osteoblasts occurred when cultured on nanophase titania sonicated in PLGA at the highest powers. In this manner, the present study demonstrates that PLGA composites with well dispersed nanophase titania can enhance osteoblast functions necessary for improved bone tissue engineering applications.

  20. Interface modified polylactic acid/starch/poly ε-caprolactone antibacterial nanocomposite blends for medical applications.

    PubMed

    Davachi, Seyed Mohammad; Shiroud Heidari, Behzad; Hejazi, Iman; Seyfi, Javad; Oliaei, Erfan; Farzaneh, Arman; Rashedi, Hamid

    2017-01-02

    In this study, an optimized interface-modified ternary blend with antibacterial activity based on polylactic acid/starch/poly ε-caprolactone (PLASCL20), mixed with nano hydroxyapatite (nHA) via melt blending. This method results in a homogeneous nanocomposite blend in which the addition of 3% nHA improves the overall properties such as hydrolytic degradation, hydrophilicity, antibacterial activity and the drug release comparing to PLASCL20. Moreover, the simultaneous use of nHA and encapsulated triclosan (LATC30) compensated the negative effect of triclosan through increasing the possible cell attachment. According to the contact angle results, nHA was thermodynamically driven into the interface of PLA and PCL/Starch phases. The addition of 3% nHA showed a good adjustment between the hydrolytic degradation and the release profile, therefore, their electrospun microfibers demonstrated an improved fibroblast (L929) cell attachment. The aforementioned nanocomposite blend is a suitable antibacterial candidate for many medical applications with minimum side effects due to the controlled release of triclosan.

  1. Bioinspired superhydrophobic poly(L-lactic acid) surfaces control bone marrow derived cells adhesion and proliferation.

    PubMed

    Alves, Natália M; Shi, Jun; Oramas, Elena; Santos, José L; Tomás, Helena; Mano, João F

    2009-11-01

    The aptitude of a cell to adhere, migrate, and differentiate on a compact substrate or scaffold is important in the field of tissue engineering and biomaterials. It is well known that cell behavior can be controlled and guided through the change in micro- and nano-scale topographic features. In this work, we intend to demonstrate that special topographic features that control wettability may also have an important role in the biological performance of biodegradable substrates. Poly(L-lactic acid) surfaces with superhydrophobic characteristics were produced, based on the so-called Lotus effect, exhibiting dual micro- and nano-scale roughness. The water contact angle could be higher than 150 degrees and a value of that order could be kept even upon immersion in a simulated body fluid solution for more than 20 days. Such water repellent surfaces were found to prevent adhesion and proliferation of bone marrow derived cells previously isolated from the femurs of 6-week-old male Wistar rats, when compared with smoother surfaces prepared by simple solvent casting. Such results demonstrate that these superhydrophobic surfaces may be used to control cell behavior onto biodegradable substrates.

  2. Poly(vinyl alcohol)-Tannic Acid Hydrogels with Excellent Mechanical Properties and Shape Memory Behaviors.

    PubMed

    Chen, Ya-Nan; Peng, Lufang; Liu, Tianqi; Wang, Yaxin; Shi, Shengjie; Wang, Huiliang

    2016-10-12

    Shape memory hydrogels have promising applications in a wide variety of fields. Here we report the facile fabrication of a novel type of shape memory hydrogels physically cross-linked with both stronger and weaker hydrogen bonding (H-bonding). Strong multiple H-bonding formed between poly(vinyl alcohol) (PVA) and tannic acid (TA) leads to their coagulation when they are physically mixed at an elevated temperature and easy gelation at room temperature. The amorphous structure and strong H-bonding endow the PVA-TA hydrogels with excellent mechanical properties, as indicated by their high tensile strengths (up to 2.88 MPa) and high elongations (up to 1100%). The stronger H-bonding between PVA and TA functions as the "permanent" cross-link and the weaker H-bonding between PVA chains as the "temporary" cross-link. The reversible breakage and formation of the weaker H-bonding imparts the PVA-TA hydrogels with excellent temperature-responsive shape memory. Wet and dried hydrogel samples with a deformed or elongated shape can recover to their original shapes when immersed in 60 °C water in a few seconds or at 125 °C in about 2.5 min, respectively.

  3. Ultrasensitive Detection of Ferulic Acid Using Poly(diallyldimethylammonium chloride) Functionalized Graphene-Based Electrochemical Sensor

    PubMed Central

    Liu, Lin-jie; Gao, Xia; Zhang, Pei; Feng, Shi-lan; Hu, Fang-di; Li, Ying-dong; Wang, Chun-ming

    2014-01-01

    The electrochemical redox of ferulic acid (FA) was investigated systematically by cyclic voltammetry (CV) with a poly(diallyldimethylammonium chloride) functionalized graphene-modified glassy carbon electrode (PDDA-G/GCE) as a working electrode. A simple and sensitive differential pulse voltammetry (DPV) technique was proposed for the direct quantitative determination of FA in Angelica sinensis and spiked human urine samples for the first time. The dependence of the intensities of currents and potentials on nature of the supporting electrolyte, pH, scan rate, and concentration was investigated. Under optimal conditions, the proposed sensor exhibited excellent electrochemical sensitivity to FA, and the oxidation peak current was proportional to FA concentration in the range of 8.95 × 10−8 M ~5.29 × 10−5 M, with a relatively low detection limit of 4.42 × 10−8 M. This fabricated sensor also displayed acceptable reproducibility, long-term stability, and high selectivity with negligible interferences from common interfering species. Besides, it was applied to detect FA in Angelica sinensis and biological samples with satisfactory results, making it a potential alternative tool for the quantitative detection of FA in pharmaceutical analysis. PMID:24900937

  4. Effect of Sterilization Methods on Electrospun Poly(lactic acid) (PLA) Fiber Alignment for Biomedical Applications.

    PubMed

    Valente, T A M; Silva, D M; Gomes, P S; Fernandes, M H; Santos, J D; Sencadas, V

    2016-02-10

    Medically approved sterility methods should be a major concern when developing a polymeric scaffold, mainly when commercialization is envisaged. In the present work, poly(lactic acid) (PLA) fiber membranes were processed by electrospinning with random and aligned fiber alignment and sterilized under UV, ethylene oxide (EO), and γ-radiation, the most common ones for clinical applications. It was observed that UV light and γ-radiation do not influence fiber morphology or alignment, while electrospun samples treated with EO lead to fiber orientation loss and morphology changing from cylindrical fibers to ribbon-like structures, accompanied to an increase of polymer crystallinity up to 28%. UV light and γ-radiation sterilization methods showed to be less harmful to polymer morphology, without significant changes in polymer thermal and mechanical properties, but a slight increase of polymer wettability was detected, especially for the samples treated with UV radiation. In vitro results indicate that both UV and γ-radiation treatments of PLA membranes allow the adhesion and proliferation of MG 63 osteoblastic cells in a close interaction with the fiber meshes and with a growth pattern highly sensitive to the underlying random or aligned fiber orientation. These results are suggestive of the potential of both γ-radiation sterilized PLA membranes for clinical applications in regenerative medicine, especially those where customized membrane morphology and fiber alignment is an important issue.

  5. Production of Poly (3-Hydroxybutyric Acid) by Ralstonia eutropha in a Biocalorimeter and its Thermokinetic Studies.

    PubMed

    Anusha, Subramanian Mohanakrishnan; Leelaram, Santharam; Surianarayanan, Mahadevan

    2016-07-01

    Bioplastic production from microbial sources is an emerging area which provides opportunities even to convert the wastes into bioplastics. Poly (3-hydroxybutyric acid), commonly called as PHB, is a bioplastic, which is stored as intracellular cytoplasmic inclusions in microorganisms. The objectives of this study are to calorimetrically monitor the PHB production and evaluate the thermokinetic data in a bioreaction calorimeter (BioRC1e). Thus, a well-known PHB-producing bacteria Ralstonia eutropha was selected for batch process in a bioreaction calorimeter. The metabolic heat generated was found to be correlated with the biomass, substrate consumption, oxygen uptake rate (OUR), carbon dioxide evolution rate (CER) and PHB production. The OUR pattern explained the oxidative metabolism of the strain R. eutropha. The heat yields due to biomass and glucose consumption during PHB production were found to be 12.56 and 13.56 kJ/g, respectively. The oxycalorific value obtained for the PHB production was 443.80 kJ/mol of O2. The concentration of PHB obtained in BioRC1e was 4.33 g/L with a production rate of 0.09 g/L/h. The chemical structure of the extracted PHB by R. eutropha was confirmed using fourier transform infrared spectroscopy (FT-IR) and (1)H and (13)C nuclear magnetic resonance (NMR) analysis.

  6. Synthesis and Biomedical Applications of Poly((meth)acrylic acid) Brushes.

    PubMed

    Qu, Zhenyuan; Xu, Hong; Gu, Hongchen

    2015-07-15

    Poly((meth)acrylic acid) (P(M)AA) brushes possess a number of distinctive properties that are particularly attractive for biomedical applications. This minireview summarizes recent advances in the synthesis and biomedical applications of P(M)AA brushes and brushes containing P(M)AA segments. First, we review different surface-initiated polymerization (SIP) methods, with a focus on recent progress in the surface-initiated controlled/living radical polymerization (SI-CLRP) techniques used to generate P(M)AA brushes with a tailored structure. Next, we discuss biomolecule immobilization methods for P(M)AA brushes, including physical adsorption, covalent binding, and affinity interactions. Finally, typical biomedical applications of P(M)AA brushes are reviewed, and their performance is discussed based on their unique properties. We conclude that P(M)AA brushes are promising biomaterials, and more potential biomedical applications are expected to emerge with the further development of synthetic techniques and increased understanding of their interactions with biological systems.

  7. Influence of neutron irradiation on holmium acetylacetonate loaded poly(L-lactic acid) microspheres.

    PubMed

    Nijsen, J F; van Het Schip, A D; van Steenbergen, M J; Zielhuis, S W; Kroon-Batenburg, L M J; van de Weert, M; van Rijk, P P; Hennink, W E

    2002-04-01

    Holmium-loaded microspheres are useful systems in radio-embolization therapy of liver metastases. For administration to a patient, the holmium-loaded microspheres have to be irradiated in a nuclear reactor to become radioactive. In this paper. the influence of neutron irradiation on poly(L-lactic acid) (PLLA) microspheres and films, with or without holmium acetylacetonate (HoAcAc), is investigated, in particular using differential scanning calorimetry (MDSC), scanning electron microscopy, gel permeation chromatography (GPC), infrared spectroscopy, and X-ray diffraction. After irradiation of the microspheres, only minor surface changes were seen using scanning electron microscopy, and the holmium complex remained immobilized in the polymer matrix as reflected by a relatively small release of this complex. GPC and MDSC measurements showed a decrease in molecular weight and crystallinity of the PLLA, respectively, which can be ascribed to radiation induced chain scission. Irradiation of the HoAcAc loaded PLLA matrices resulted in evaporation of the non-coordinated and one coordinated water molecule of the HoAcAc complex, as evidenced by MDSC and X-ray diffraction analysis. Infrared spectroscopy indicated that some degradation of the acetylacetonate anion occurred after irradiation. Although some radiation induced damage of both the PLLA matrix and the embedded HoAcAc-complex occurs, the microspheres retain their favourable properties (no marginal release of Ho, preservation of the microsphere size), which make these systems interesting candidates for the treatment of tumours by radio-embolization.

  8. Near-infrared (NIR) disrelation mapping analysis for poly(lactic) acid nanocomposite.

    PubMed

    Shinzawa, Hideyuki; Mizukado, Junji

    2017-03-14

    Near infrared (NIR) imaging data of poly(lactic) acid (PLA) nanocomposite were analysed by disrelation mapping to prove the possible interaction between PLA matrix and montmorillonite-based nanoclay. The basic concept of disrelation mapping can be viewed as a spatial filter based on two-dimensional (2D) correlation function to elucidate specific areas where disrelated variation between intensities occurs. Correlation intensity develops on disrelation map only if spectral intensities at v1 and v2 within the local spatial area vary in a dissimilar manner. This feature is especially suitable for identifying the area where interaction between components occurs, which is not fully detected by the conventional visualizations based on a single wavenumber. Disrelation maps constructed with NIR bands arising from the crystalline and amorphous components of the PLA. The pattern appearing on the disrelation map indicated different distributions of the crystalline and amorphous components of the nanocomposite sample. In addition, the development of disrelation intensity becomes acute especially at the area adjacent to the clay, revealing that the clay essentially works as nucleating agent to cause the additional development of crystalline structure of PLA by lowering the surface energy barrier.

  9. Preparation, cell compatibility and degradability of collagen-modified poly(lactic acid).

    PubMed

    Cui, Miaomiao; Liu, Leili; Guo, Ning; Su, Ruixia; Ma, Feng

    2015-01-05

    Poly(lactic acid) (PLA) was modified using collagen through a grafting method to improve its biocompatibility and degradability. The carboxylic group at the open end of PLA was transferred into the reactive acylchlorided group by a reaction with phosphorus pentachloride. Then, collagen-modified PLA (collagen-PLA) was prepared by the reaction between the reactive acylchlorided group and amino/hydroxyl groups on collagen. Subsequently, the structure of collagen-PLA was confirmed by Fourier transform infrared spectroscopy, fluorescein isothiocyanate-labeled fluorescence spectroscopy, X-ray photoelectron spectroscopy, and DSC analyses. Finally, some properties of collagen-PLA, such as hydrophilicity, cell compatibility and degradability were characterized. Results showed that collagen had been grafted onto the PLA with 5% graft ratio. Water contact angle and water absorption behavior tests indicated that the hydrophilicity of collagen-PLA was significantly higher than that of PLA. The cell compatibility of collagen-PLA with mouse embryonic fibroblasts (3T3) was also significantly better than PLA in terms of cell morphology and cell proliferation, and the degradability of PLA was also improved after introducing collagen. Results suggested that collagen-PLA was a promising candidate for biomedical applications.

  10. Evaluation of poly(lactic-co-glycolic acid) plate and screw system for bone fixation.

    PubMed

    Park, Subin; Kim, Jin Hee; Kim, Il Hwan; Lee, Minsu; Heo, Suhak; Kim, Hong; Kim, Eun Hee; Choy, Young Bin; Heo, Chan Yeong

    2013-05-01

    In this study, we investigated the efficacy and safety of the recently developed modifiable bioabsorbable plates and screws, which are made of PLGA [poly(lactic-co-glycolic acids)]. An in vitro extract test and a mammalian erythrocyte micronucleus test revealed that neither cytotoxicity nor genotoxicity was observed with the plates and screws tested in this study. An in vivo mandible fracture model in rabbit was introduced to evaluate the in vivo efficacy and of the PLGA-based plates and screws. At 4, 6, 8, and 10 weeks after implantation, tissue specimens were taken from the implanted sites of the rabbits and a histologic analysis was performed for each of the specimens. After 4 weeks, the plate was covered by connective tissues and severe chronic active inflammation in soft tissue was observed. After 6 weeks, the inflammation decreased and some of the specimens exhibited new bone formation around the periosteum. After 8 and 10 weeks, new bone formation was observed with all samples, where almost no severe inflammation was involved, implying the healing of the fracture. Given these, it can be suggested that the biodegradable plate and screw system that we evaluated in this study is effective for treatment of mandible fracture, one of the regions under a high load-bearing condition. The adjustment process and the long-term follow-up study are in progress for clinical application of the plate and screw system introduced in this study.

  11. Interfacial properties of hydrophilized poly(lactic-co-glycolic acid) layers with various thicknesses.

    PubMed

    Gyulai, G; Pénzes, Cs B; Mohai, M; Lohner, T; Petrik, P; Kurunczi, S; Kiss, É

    2011-10-15

    Biodegradable polyesters such as poly(lactic-co-glycolic acid) copolymers (PLGA) are preferred materials for drug carrier systems although their surface hydrophobicity greatly limits their use in controlled drug delivery. PLGA thin films on a solid support blended with PEG-containing compound (Pluronic) were used as model systems to study the interfacial interactions with aqueous media. Degree of surface hydrophilization was assessed by wettability, and X-ray photoelectron spectroscopy (XPS) measurements. Protein adsorption behavior was investigated by in situ spectroscopic ellipsometry. The degree of protein adsorption showed a good correlation with the hydrophilicity, and surface composition. Unexpectedly, the layer thickness was found to have a great impact on the interfacial characteristics of the polymer films in the investigated regime (20-200 nm). Thick layers presented higher hydrophilicity and great resistance to protein adsorption. That special behavior was explained as the result of the swelling of the polymer film combined with the partial dissolution of Pluronic from the layer. This finding might promote the rational design of surface modified biocompatible nanoparticles.

  12. Material characterization of poly-lactic acid shelled ultrasound contrast agent and their dynamics

    NASA Astrophysics Data System (ADS)

    Paul, Shirshendu; Russakow, Daniel; Rodgers, Tyler; Sarkar, Kausik; Cochran, Michael; Wheatley, Margaret

    2011-11-01

    Micron-size gas bubbles encapsulated with lipids and proteins are used as contrast enhancing agents for ultrasound imaging. Biodegradable polymer poly-lactic acid (PLA) has recently been suggested as a possible means of encapsulation. Here, we report in vitro measurement of attenuation and scattering of ultrasound through an emulsion of PLA agent as well as theoretical modeling of the encapsulated bubble dynamics. The attenuation measured with three different transducers of central frequencies 2.25, 3.5 and 5 MHz, shows a peak around 2-3 MHz. These bubbles also show themselves to possess excellent scattering characteristics including strong non-linear response that can be used for harmonic and sub-harmonic contrast imaging. Our recently developed interfacial rheological models are applied to describe the dynamics of these bubbles; rheological model properties are estimated using measured attenuation data. The model is then applied to predict nonlinear scattered response, and the prediction is compared against experimental observation. Partially supported by NSF and NIH.

  13. Comparative receptor based brain delivery of tramadol-loaded poly(lactic-co-glycolic acid) nanoparticles.

    PubMed

    Lalani, Jigar; Raichandani, Yogesh; Mathur, Rashi; Lalan, Manisha; Chutani, Krishna; Mishra, Anil Kumar; Misra, Ambikanandan

    2012-12-01

    Receptor mediated endocytosis or transcytosis has been reported for drug delivery across Blood-brain barrier (BBB) and hence, the aim of the present investigations was to prepare and compare brain targeting efficiency of tramadol-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles surface modified with transferrin (Tf) and lactoferrin (Lf). Nanoparticles of tramadol were prepared using nanoprecipitation technique and surface conjugated with Tf and Lf using epoxy linker. Prepared nanoparticles were characterized for their size, surface charge, drug entrapment, transmission electron microscopy and in vitro drug release. The surface density of Tf and Lf was estimated by protein estimation. The drug distribution in blood, brain and other tissues was studied in mice after intravenous administration. Tf and Lf anchored nanoparticles exhibit enhanced uptake with 2.38 and 3.85 folds higher targeting respectively in the brain when compared with unconjugated nanoparticles. The brain targeting observed for Lf anchored PLGA nanoparticles (Lf-TMD-PLGA-NP) was 1.62 folds that of Tf anchored PLGA nanoparticles (Tf-TMD-PLGA-NP). Hence, the study revealed Tf and specially Lf as promising ligand for enhanced brain deposition of tramadol.

  14. All Biomass and UV Protective Composite Composed of Compatibilized Lignin and Poly (Lactic-acid)

    PubMed Central

    Kim, Youngjun; Suhr, Jonghwan; Seo, Hee-Won; Sun, Hanna; Kim, Sanghoon; Park, In-Kyung; Kim, Soo-Hyun; Lee, Youngkwan; Kim, Kwang-Jin; Nam, Jae-Do

    2017-01-01

    Utilization of carbon-neutral biomass became increasingly important due to a desperate need for carbon reduction in the issue of global warming in light of replacing petroleum-based materials. We used lignin, which was an abundant, low cost, and non-food based biomass, for the development of all biomass-based films and composites through reactive compatibilization with poly (lactic-acid) (PLA). Using a facile and practical route, the hydrophilic hydroxyl groups of lignin were acetylated to impose the compatibility with PLA. The solubility parameter of the pristine lignin at 26.3 (J/cm3)0.5 was altered to 20.9 (J/cm3)0.5 by acetylation allowing the good compatibility with PLA at 20.2 (J/cm3)0.5. The improved compatibility of lignin and PLA provided substantially decreased lignin domain size in composites (12.7 μm), which subsequently gave transparent and UV-protection films (visual transmittance at 76% and UV protection factor over 40). The tensile strength and elongation of the developed composite films were increased by 22% and 76%, respectively, and the biobased carbon content was confirmed as 96 ± 3%. The developed PLA/lignin composites provided 100% all-biomass contents and balanced optical and mechanical properties that could broaden its eco-friendly applications in various industries.

  15. Nanostructured medical device coatings based on self-assembled poly(lactic-co-glycolic acid) nanoparticles.

    PubMed

    Dayyoub, Eyas; Hobler, Christian; Nonnweiler, Pierina; Keusgen, Michael; Bakowsky, Udo

    2013-07-01

    Here we present a new method for providing nanostructured drug-loaded polymer films which enable control of film surface morphology and delivery of therapeutic agents. Silicon wafers were employed as models for implanted biomaterials and poly(lactic-co-glycolic acid) (PLGA) nanoparticles were assembled onto the silicon surface by electrostatic interaction. Monolayers of the PLGA particles were deposited onto the silicon surface upon incubation in an aqueous particle suspension. Particle density and surface coverage of the silicon wafers were varied by altering particle concentration, incubation time in nanoparticle suspension and ionic strength of the suspension. Dye loaded nanoparticles were prepared and assembled to silicon surface to form nanoparticle films. Fluorescence intensity measurements showed diffusion-controlled release of the dye over two weeks and atomic force microscopy (AFM) analysis revealed that these particles remained attached to the surface during the incubation time. This work suggests that coating implants with PLGA nanoparticles is a versatile technique which allows drug release from the implant surface and modulation of surface morphology.

  16. Fabrication of poly(γ-glutamic acid) monolith by thermally induced phase separation and its application.

    PubMed

    Park, Sung-Bin; Fujimoto, Takashi; Mizohata, Eiichi; Inoue, Tsuyoshi; Sung, Moon-Hee; Uyama, Hiroshi

    2013-01-01

    Monoliths are functional porous materials with a three-dimensional continuous interconnected pore structure in a single piece. A monolith with uniform shape based on poly(γ-glutamic acid) (PGA) has been prepared via a thermally induced phase separation technique using a mixture of dimethyl sulfoxide, water, and ethanol as solvent. The morphology of the obtained monolith was observed by scanning electron microscopy and the surface area of the monolith was evaluated by the Brunauer Emmett Teller method. The effects of fabrication parameters such as the concentration and molecular mass of PGA and the solvent composition have been systematically investigated. The PGA monolith was cross-linked with hexamethylene diisocyanate to produce the water-insoluble monolith. The addition of sodium chloride to the phase separation solvent affected the properties of the cross-linked monolith. The swelling ratio of the cross-linked monolith toward aqueous solutions depended on the buffer pH as well as the monolith fabrication condition. Copper(II) ion was efficiently adsorbed on the cross-linked PGA monolith, and the obtained copper-immobilized monolith showed strong antibacterial activity for Escherichia coli. By combination of the characteristic properties of PGA (e.g., high biocompatibility and biodegradability) and the unique features of monoliths (e.g., through-pore structure, large surface area, and high porosity with small pore size), the PGA monolith possesses large potentials for various industrial applications in the biomedical, environmental, analytical, and separation fields.

  17. Preparation of poly(γ-glutamic acid)/hydroxyapatite monolith via biomineralization for bone tissue engineering.

    PubMed

    Park, Sung-Bin; Hasegawa, Urara; van der Vlies, André J; Sung, Moon-Hee; Uyama, Hiroshi

    2014-01-01

    A hybrid monolith of poly(γ-glutamic acid) and hydroxyapatite (PGA/HAp monolith) was prepared via biomineralization and used as a macroporous cell scaffold in bone tissue engineering. The PGA monolith having a bimodal pore size distribution was used as a substrate to induce biomineralization. The PGA/HAp monolith was obtained by immersing the PGA monolith in simulated body fluid. Pretreatment with CaCl2 enhanced the apatite-forming ability of the PGA monolith. Murine osteoblastic MC3T3-E1 cells efficiently attached and proliferated on the PGA/HAp monolith. MTT assay showed that both the PGA and PGA/HAp monolith did not have apparent cytotoxicity. Moreover, the PGA and PGA/HAp monoliths adsorbed bone morphogenetic protein-2 (BMP-2) by electrostatic interaction which was slowly released in the medium during cell culture. The PGA/HAp monolith enhanced BMP-2 induced alkaline phosphatase activity compared to the PGA monolith and a polystyrene culture plate. Thus, these PGA/HAp monoliths may have potential in bone tissue engineering.

  18. Cell morphology of extrusion foamed poly(lactic acid) using endothermic chemical foaming agent.

    PubMed

    Matuana, Laurent M; Faruk, Omar; Diaz, Carlos A

    2009-12-01

    Poly(lactic acid) (PLA) was foamed with an endothermic chemical foaming agent (CFA) through an extrusion process. The effects of polymer melt flow index, CFA content, and processing speed on the cellular structures, void fraction, and cell-population density of foamed PLA were investigated. The apparent melt viscosity of PLA was measured to understand the effect of melt index on the cell morphology of foamed PLA samples. The void fraction was strongly dependent on the PLA melt index. It increased with increasing melt index, reaching a maximum value, after which it decreased. Melt index showed no significant effect on the cell-population density of foamed samples within the narrow range studied. A gas containment limit was observed in PLA foamed with CFA. Both the void fraction and cell-population density increased with an initial increase in CFA content, reached a maximum value, and then decreased as CFA content continued to increase. The processing speed also affected the morphology of PLA foams. The void fraction reached a maximum value as the extruder's screw speed increased to 40 rpm and a further increase in the processing speed tended to reduce the void fraction of foamed samples. By contrast, cell-population density increased one order of magnitude by increasing the screw speed from 20 to 120 rpm. The experimental results indicate that a homogeneous and finer cellular morphology could be successfully achieved in PLA foamed in an extrusion process with a proper combination of polymer melt flow index, CFA content, and processing speed.

  19. Drug delivery systems using sandwich configurations of electrospun poly(lactic acid) nanofiber membranes and ibuprofen.

    PubMed

    Immich, Ana Paula Serafini; Arias, Manuel Lis; Carreras, Núria; Boemo, Rafael Luís; Tornero, José Antonio

    2013-10-01

    The primary advantages of electrospun membranes include the ability to obtain very thin fibers that are on the order of magnitude of several nanometers with a considerable superficial area and the possibility for these membranes to be manipulated and processed for many different applications. The purpose of this study is to evaluate and quantify the transport mechanisms that control the release of drugs from polymer-based sandwich membranes produced using the electrospinning processes. These electrospun membranes were composed of poly(lactic acid) (PLA) because it is one of the most promising biodegradable polymers due to its mechanical properties, thermoplastic processability and biological properties, such as its biocompatibility and biodegradability. The transport mechanism that controls the drug delivery was evaluated via the release kinetics of a bioactive agent in physiological serum, which was used as a corporal fluid simulation. To describe the delivery process, mathematical models, such as the Power Law, the classical Higuchi equation and an approach to Fick's Second Law were used. Using the applied mathematical models, it is possible to conclude that control over the release of the drug is significantly dependent on the thickness of the membrane rather than the concentration of the drug.

  20. Fabrication and biocompatibility of collagen sponge reinforced with poly(glycolic acid) fiber.

    PubMed

    Hiraoka, Yosuke; Kimura, Yu; Ueda, Hiroki; Tabata, Yasuhiko

    2003-12-01

    This article describes an investigation of collagen sponge mechanically reinforced through the incorporation of poly(glycolic acid) (PGA) fiber. A collagen solution with PGA fiber homogeneously dispersed at collagen:PGA weight ratios of 1.5, 0.8, 0.4, and 0.2 was freeze-dried, followed by dehydrothermal cross-linking to obtain collagen sponges incorporating PGA fiber to various extents. By scanning electron microscopy observation, the collagen sponges exhibited isotropic and interconnected pore structures with an average size of 180 microm, irrespective of PGA fiber incorporation. As expected, PGA fiber incorporation enabled the collagen sponges to significantly enhance their compression strength. In vitro cell culture studies revealed that the number of L929 fibroblasts initially attached was significantly greater for any collagen sponge incorporating PGA fiber than for collagen sponge. The shrinkage of sponge after cell seeding was suppressed by fiber incorporation. It is possible that shrinkage suppression results in the superior cell attachment of sponge incorporating PGA fiber. After subcutaneous implantation into the backs of mice, the residual volume of collagen sponge incorporating PGA fiber was significant compared with that of collagen sponge and increased with a decrease in the collagen:PGA ratio. The greater number of cells infiltrated and deeper infiltration were observed for collagen sponge incorporating PGA fiber implanted subcutaneously. We conclude that the incorporation of PGA fiber is a simple and promising way to reinforce collagen sponge without impairing biocompatibility.

  1. Activated carbon fibers/poly(lactic-co-glycolic) acid composite scaffolds: preparation and characterizations.

    PubMed

    Shi, Yanni; Han, Hao; Quan, Haiyu; Zang, Yongju; Wang, Ning; Ren, Guizhi; Xing, Melcolm; Wu, Qilin

    2014-10-01

    The present work is a first trial to introduce activated carbon fibers (ACF) with high adsorption capacity into poly(lactic-co-glycolic) acid (PLGA), resulting in a novel kind of scaffolds for tissue engineering applications. ACF, prepared via high-temperature processing of carbon fibers, are considered to possess bioactivity and biocompatibility. The ACF/PLGA composite scaffolds are prepared by solvent casting/particulate leaching method. Increments in both pore quantity and quality over the surface of ACF as well as a robust combination between ACF and PLGA matrix are observed via scanning electron microscopy (SEM). The high adsorption capacity of ACF is confirmed by methylene blue solution absorbency test. The surfaces of ACF are affiliated with many hydrophilic groups and characterized by Fourier transform infrared spectroscopy. Furthermore, the SEM images show that cells possess a favorable spreading morphology on the ACF/PLGA scaffolds. Besides, vivo experiments are also carried out to evaluate the histocompatibility of the composite scaffolds. The results show that ACF have the potential to become one of the most promising materials in biological fields.

  2. Poly(lactic acid)/chitosan hybrid nanoparticles for controlled release of anticancer drug.

    PubMed

    Wang, Wenlong; Chen, Shu; Zhang, Liang; Wu, Xi; Wang, Jiexin; Chen, Jian-Feng; Le, Yuan

    2015-01-01

    Poly(lactic acid) (PLA) is a kind of non-toxic biological materials with excellent absorbability, biocompatibility and biodegradability, which can be used for drug release, tissue engineering and surgical treatment applications. In this study, we prepared chitosan modified PLA nanoparticles as carriers for encapsulation of docetaxel by anti-solvent precipitation method. The morphology, particle size, zeta potential and composition of the PLA/chitosan were characterized by SEM, DLS, FTIR and XPS. As-prepared PLA/chitosan particles exhibited average size of 250 nm and showed very narrow distribution with polydispersity index of 0.098. Their large surface charge-ability was confirmed by zeta potential value of 53.9 mV. Docetaxel was released from PLA/chitosan nanoparticles with 40% initial burst release in 5 h and 70% cumulative release within 24 h, while from PLA nanoparticles 65% of docetaxel was released in 5h. In vitro drug release study demonstrated that PLA/chitosan nanoparticles prolonged drug release and decreased the burst release over the unmodified PLA nanoparticles. These results illustrated high potential of chitosan modified PLA nanoparticles for usage as anticancer drug carriers.

  3. Poly(lactic-co-glycolic) Acid-Chitosan Dual Loaded Nanoparticles for Antiretroviral Nanoformulations

    PubMed Central

    Makita-Chingombe, Faithful; Kutscher, Hilliard L.; DiTursi, Sara L.; Morse, Gene D.; Maponga, Charles C.

    2016-01-01

    Poly(lactic-co-glycolic acid) (PLGA) chitosan (CS) coated nanoparticles (NPs) were loaded with two antiretrovirals (ARVs) either lamivudine (LMV) which is hydrophilic or nevirapine (NVP) which is hydrophobic or both LMV and NVP. These ARVs are of importance in resource-limited settings, where they are commonly used in human immunodeficiency virus (HIV-1) treatment due to affordability and accessibility. NPs prepared by a water-oil-water emulsion and reduced pressure solvent evaporation technique were determined to have a positive zeta potential, a capsule-like morphology, and an average hydrodynamic diameter of 240 nm. Entrapment of NVP as a single ARV had a notable increase in NP size compared to LMV alone or in combination with LMV. NPs stored at room temperature in distilled water maintained size, polydispersity (PDI), and zeta potential for one year. No changes in size, PDI, and zeta potential were observed for NPs in 10% sucrose in lyophilized or nonlyophilized states stored at 4°C and −20°C, respectively. Freezing NPs in the absence of sucrose increased NP size. Drug loading, encapsulation efficiency, and kinetic release profiles were quantified by high performance liquid chromatography (HPLC). Our novel nanoformulations have the potential to improve patient outcomes and expand drug access in resource-limited countries for the treatment of HIV-1. PMID:27190651

  4. Amycolatopsis thailandensis sp. nov., a poly(L-lactic acid)-degrading actinomycete, isolated from soil.

    PubMed

    Chomchoei, Atchareeya; Pathom-Aree, Wasu; Yokota, Akira; Kanongnuch, Chartchai; Lumyong, Saisamorn

    2011-04-01

    A novel actinomycete that was capable of degrading poly(l-lactic acid), strain CMU-PLA07(T), was isolated from soil in northern Thailand. Strain CMU-PLA07(T) had biochemical, chemotaxonomic, morphological and physiological properties that were consistent with its classification in the genus Amycolatopsis. 16S rRNA gene sequence analysis showed that the isolate formed a phyletic line within the genus Amycolatopsis. Strain CMU-PLA07(T) was most similar to Amycolatopsis coloradensis IMSNU 22096(T) (99.5 % 16S rRNA gene sequence similarity) and Amycolatopsis alba DSM 44262(T) (99.4 %). However, strain CMU-PLA07(T) was distinguishable from the type strains of species of the genus Amycolatopsis on the basis of DNA-DNA relatedness and phenotypic data. Therefore, strain CMU-PLA07(T) is considered to represent a novel species of the genus Amycolatopsis, for which the name Amycolatopsis thailandensis sp. nov. is proposed. The type strain is CMU-PLA07(T) ( = JCM 16380(T) = BCC 38279(T)).

  5. Softened and flexible biodegradable poly(lactic acid) and its electromechanical properties for actuator application.

    PubMed

    Thummarungsan, Natlita; Pattavarakorn, Datchanee; Sirivat, Anuvat

    2016-12-01

    Poly (lactic acid) (PLA) is a biodegradable polymer with high stiffness presenting a limitation for using in actuator applications. Adding a plasticizer is one way to solve this problem to enhance flexibility and improve electromechanical properties of pristine PLA. In this work, the PLA films were prepared via a simple solvent casting method. The influences of plasticizer type and electric field strength on electromechanical behavior of PLA films were investigated by the melt rheometer and bending measurement. For the PLA films filled with dibutyl phthalate (DBP), the storage modulus, G', immediately increased towards its steady state and rapidly recovered to its original value with and without electric field, respectively, which can be referred to a reversible system. On the other hand, the PLA film with Tween 20 processed the highest ∆G׳/G׳0 of 1.34 due to the available amount of polarized groups. In the bending measurement, the dielectrophoresis forces of plasticized PLA films were found to increase with increasing electric field where the deflections occurred towards anode side as the polarized groups generated negative charges. The DBP_PLA1.5D film exhibited the greatest bending and dielectrophoresis force. Thus, the biodegradable PLA along with DBP combine to have a great potential towards actuator application.

  6. Poly(lactic-co-glycolic) acid drug delivery systems through transdermal pathway: an overview.

    PubMed

    Naves, Lucas; Dhand, Chetna; Almeida, Luis; Rajamani, Lakshminarayanan; Ramakrishna, Seeram; Soares, Graça

    2017-02-06

    In past few decades, scientists have made tremendous advancement in the field of drug delivery systems (DDS), through transdermal pathway, as the skin represents a ready and large surface area for delivering drugs. Efforts are in progress to design efficient transdermal DDS that support sustained drug release at the targeted area for longer duration in the recommended therapeutic window without producing side-effects. Poly(lactic-co-glycolic acid) (PLGA) is one of the most promising Food and Drug Administration approved synthetic polymers in designing versatile drug delivery carriers for different drug administration routes, including transdermal drug delivery. The present review provides a brief introduction over the transdermal drug delivery and PLGA as a material in context to its role in designing drug delivery vehicles. Attempts are made to compile literatures over PLGA-based drug delivery vehicles, including microneedles, nanoparticles, and nanofibers and their role in transdermal drug delivery of different therapeutic agents. Different nanostructure evaluation techniques with their working principles are briefly explained.

  7. Novel poly(ethylene-co-acrylic acid) nanofibrous biomaterials for peptide synthesis and biomedical applications.

    PubMed

    Xiang, Bei; Sun, Gang; Lam, Kit S; Xiao, Kai

    2010-10-01

    Poly(ethylene-co-acrylic acid) (PE-co-AA) fibers in sizes of 200-500 nm were prepared by using a novel melt-extrusion-extraction fabrication process. The thermoplastic nanofibers could be controllably dispersed and reassembled by a novel solvent exchange filtration method. The dispersed PE-co-AA nanofibers possess active surface areas and could directly conduct chemical reactions on surfaces. Surface modifications and organic synthesis on the nanofibers were proven effective and controllable after the dispersion. Multistep synthesis of biomolecules, such as peptide ligand HWRGWV against Fc portion of human IgG, was successful. The surface-anchored ligand has shown bioactivity through selective binding to and staining by human IgG-alkaline phosphatase conjugate. Another peptide, LXY3, a selective cyclic peptide ligand against alpha3beta1 integrin of MDA-MB-231 breast cancer cells, was also prepared on the surfaces of the dispersed nanofibers. The results showed that MDA-MB-231 cells were able to specifically bind to and grow on surfaces of the nanofibers that were functionalized with LXY3.

  8. MULTIFUNCTIONAL SYNTHETIC POLY(L-GLUTAMIC ACID)-BASED CANCER THERAPEUTIC AND IMAGING AGENTS

    PubMed Central

    Melancon, Marites P.

    2012-01-01

    Modern polymer chemistry has led to the generation of a number of biocompatible synthetic polymers have been increasingly studied as efficient carriers for drugs and imaging agents. Synthetic biocompatible polymers have been used to improve the efficacy of both small-molecular-weight therapeutics and imaging agents. Furthermore, multiple targeted anticancer agents and/or imaging reporters can be attached to a single polymer chain, allowing multifunctional and/or multimodality therapy and molecular imaging. Having both an anticancer drug and an imaging reporter in a single polymer chain allows noninvasive real-time visualization of the pharmacokinetics of polymeric drug delivery systems, which can uncover and explain the complicated mechanisms of in vivo drug delivery and their correlation to pharmacodynamics. This review examines use of the synthetic biocompatible polymer poly(L-glutamic acid) (PG) as an efficient carrier of cancer therapeutics and imaging agents. This review will summarize and update our recent research on use of PG as a platform for drug delivery and molecular imaging, including recent clinical findings with respect to PG-paclitaxel (PG-TXL); the combination of PG-TXL with radiotherapy; mechanisms of action of PG-TXL; and noninvasive visualization of in vivo delivery of polymeric conjugates with contrast-enhanced magnetic resonance imaging (MRI), optical imaging, and multimodality imaging. PMID:21303613

  9. Physico-mechanical properties of poly(lactic acid) biocomposites reinforced with cow dung

    NASA Astrophysics Data System (ADS)

    Yusefi, Mostafa; Khalid, Mohammad; Yasin, Faizah Md; Ketabchi, Mohammad Reza; Hajalilou, Abdollah; Chuah Abdullah, Luqman

    2017-02-01

    The aim of this work is to investigate the reinforcing effects of cow dung (CD) on poly(lactic acid) (PLA) properties. The PLA/CD biocomposite blends with different CD ratios (0–50 wt.%) were prepared using an internal Brabender mixer followed by compression molding. The results showed an enhancement in flexural properties and an acceptable drop in tensile and impact strength with increasing CD loading. Incorporation of CD also led to an overall decline in thermal stability of the biocomposites. However, an improvement in dynamic mechanical properties of the biocomposites was recorded. For PLA based biocomposites, above T g (60–65 °C), a difference in the dynamic modulus becomes more pronounced as the polymer shifts from glassy to rubbery state. SEM micrographs displayed an increase in the voids and surface roughness of biocomposites with increasing CD content. It was demonstrated that high strength, high modulus PLA/CD biocomposites can be fabricated with effective stress transfer even at 50 wt.% CD loading.

  10. Rigidity of poly-L-glutamic acid scaffolds: Influence of secondary and supramolecular structure

    SciTech Connect

    Nickels, Jonathan D.; Perticaroli, Stefania; Ehlers, Georg; Feygenson, Mikhail; Sokolov, Alexei P.

    2015-01-01

    Poly-L-glutamic acid (PGA) is a widely used biomaterial, with applications ranging from drug delivery and biological glues to food products and as a tissue engineering scaffold. A biodegradable material with flexible conjugation functional groups, tunable secondary structure, and mechanical properties, PGA has potential as a tunable matrix material in mechanobiology. Some recent studies in proteins connecting dynamics, nanometer length scale rigidity, and secondary structure suggest a new point of view from which to analyze and develop this promising material. Our paper characterizes the structure, topology, and rigidity properties of PGA prepared with different molecular weights and secondary structures through various techniques including scanning electron microscopy, FTIR, light, and neutron scattering spectroscopy. On the length scale of a few nanometers, rigidity is determined by hydrogen bonding interactions in the presence of neutral species and by electrostatic interactions when the polypeptide is negatively charged. Finally, when probed over hundreds of nanometers, the rigidity of these materials is modified by long range intermolecular interactions that are introduced by the supramolecular structure.

  11. Alginate/Poly(γ-glutamic Acid) Base Biocompatible Gel for Bone Tissue Engineering

    PubMed Central

    Chan, Wing P.; Kung, Fu-Chen; Kuo, Yu-Lin; Yang, Ming-Chen; Lai, Wen-Fu Thomas

    2015-01-01

    A technique for synthesizing biocompatible hydrogels by cross-linking calcium-form poly(γ-glutamic acid), alginate sodium, and Pluronic F-127 was created, in which alginate can be cross-linked by Ca2+ from Ca–γ-PGA directly and γ-PGA molecules introduced into the alginate matrix to provide pH sensitivity and hemostasis. Mechanical properties, swelling behavior, and blood compatibility were investigated for each hydrogel compared with alginate and for γ-PGA hydrogel with the sodium form only. Adding F-127 improves mechanical properties efficiently and influences the temperature-sensitive swelling of the hydrogels but also has a minor effect on pH-sensitive swelling and promotes anticoagulation. MG-63 cells were used to test biocompatibility. Gelation occurred gradually through change in the elastic modulus as the release of calcium ions increased over time and caused ionic cross-linking, which promotes the elasticity of gel. In addition, the growth of MG-63 cells in the gel reflected nontoxicity. These results showed that this biocompatible scaffold has potential for application in bone materials. PMID:26504784

  12. Low temperature dielectric relaxation of poly (L-lactic acid) (PLLA) by Thermally Stimulated Depolarization Current

    NASA Astrophysics Data System (ADS)

    Mishra Patidar, Manju; Jain, Deepti; Nath, R.; Ganesan, V.

    2016-10-01

    Poly (L-lactic acid) (PLLA) is a biodegradable and biocompatible polyester that can be produced by renewable resources, like corn. Being non-toxic to human body, PLLA is used in biomedical applications, like surgical sutures, bone fixation devices, or controlled drug delivery. Besides its application studies, very few experiments have been done to study its dielectric relaxation in the low temperature region. Keeping this in mind we have performed a low temperature thermally stimulated depolarization current (TSDC) studies over the temperature range of 80K-400K to understand the relaxation phenomena of PLLA. We could observe a multi modal broad relaxation of small but significant intensity at low temperatures while a sharp and high intense peak around glass transition temperature, Tg∼ 333K, of PLLA has appeared. The fine structure of the low temperature TSDC peak may be attributed to the spherulites formation of crystallite regions inter twinned with the polymer as seen in AFM and appear to be produced due to an isothermal crystallization process. XRD analysis also confirms the semicrystalline nature of the PLLA film.

  13. Dendrigraft polylysine coated-poly(glycolic acid) fibrous scaffolds for hippocampal neurons.

    PubMed

    Kojima, Chie; Fusaoka-Nishioka, Eri; Imai, Toshio; Nakahira, Atsushi; Onodera, Hiroshi

    2016-11-01

    Poly(glycolic acid) (PGA) fibers are a good candidate material for nerve cell scaffolds, which is applicable to the treatment of peripheral nerve injuries. Polylysine is widely used as a coating material for cell substrates to promote nerve cell adhesion. In this study, linear and dendrigraft polylysines were used to coat PGA fibers. The association of large dendrigraft polylysines with PGA fibers was lower and unstable, compared with linear polylysine. However, more hippocampal neurons adhered to PGA fibers coated with large dendrigraft polylysine than linear polylysine. Enhanced cell adhesion was observed, even when the dendrigraft polylysine was coated on the PGA fibers at a low concentration (0.05 μg/mL) or when it was coated in water instead of alkaline buffer. Differences in cell adhesion properties were seen between the dendrigraft polylysine coating and a laminin coating. Thus, large dendrigraft polylysines are a useful coating material for nerve cell scaffolds. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2744-2750, 2016.

  14. All Biomass and UV Protective Composite Composed of Compatibilized Lignin and Poly (Lactic-acid)

    NASA Astrophysics Data System (ADS)

    Kim, Youngjun; Suhr, Jonghwan; Seo, Hee-Won; Sun, Hanna; Kim, Sanghoon; Park, In-Kyung; Kim, Soo-Hyun; Lee, Youngkwan; Kim, Kwang-Jin; Nam, Jae-Do

    2017-03-01

    Utilization of carbon-neutral biomass became increasingly important due to a desperate need for carbon reduction in the issue of global warming in light of replacing petroleum-based materials. We used lignin, which was an abundant, low cost, and non-food based biomass, for the development of all biomass-based films and composites through reactive compatibilization with poly (lactic-acid) (PLA). Using a facile and practical route, the hydrophilic hydroxyl groups of lignin were acetylated to impose the compatibility with PLA. The solubility parameter of the pristine lignin at 26.3 (J/cm3)0.5 was altered to 20.9 (J/cm3)0.5 by acetylation allowing the good compatibility with PLA at 20.2 (J/cm3)0.5. The improved compatibility of lignin and PLA provided substantially decreased lignin domain size in composites (12.7 μm), which subsequently gave transparent and UV-protection films (visual transmittance at 76% and UV protection factor over 40). The tensile strength and elongation of the developed composite films were increased by 22% and 76%, respectively, and the biobased carbon content was confirmed as 96 ± 3%. The developed PLA/lignin composites provided 100% all-biomass contents and balanced optical and mechanical properties that could broaden its eco-friendly applications in various industries.

  15. Modulating the Rigidity and Mineralization of Collagen Gels Using Poly(Lactic-Co-Glycolic Acid) Microparticles

    PubMed Central

    DeVolder, Ross J.; Kim, Il Won; Kim, Eun-Suk

    2012-01-01

    Extensive efforts have been made to prepare osteoconductive collagen gels for the regeneration of normal bone and the pathological examination of diseased bone; however, collagen gels are often plagued by limited controllability of their rigidity and mineral deposition. This study reports a simple but efficient strategy that tunes the mechanical properties of, and apatite formation in, collagen gels by incorporating hydrolyzable poly(lactic-co-glycolic acid) (PLGA) microparticles within the gels. The PLGA microparticles are associated with the collagen fibrils and increased both the gel's elasticity and rigidity while minimally influencing its permeability. As compared with pure collagen gels, the PLGA microparticle-filled collagen gels, termed PLGA-Col hydrogels, significantly enhanced the deposition of apatite-like minerals within the gels when incubated in simulated body fluid or encapsulated with mesenchymal stem cells (MSCs) undergoing osteogenic differentiation. Finally, PLGA-Col hydrogels mineralized by differentiated MSCs led to an enhanced formation of bone-like tissues within the hydrogels. Overall, the PLGA-Col hydrogel system developed in this study will serve to improve the quality of osteoconductive matrices for both fundamental and clinical studies that are relevant to bone repair, regeneration, and pathogenesis. PMID:22480235

  16. Poly(Lactic Acid) Filled with Cassava Starch-g-Soybean Oil Maleate

    PubMed Central

    Kiangkitiwan, Nopparut; Srikulkit, Kawee

    2013-01-01

    Poly(lactic acid), PLA, is a biodegradable polymer, but its applications are limited by its high cost and relatively poorer properties when compared to petroleum-based plastics. The addition of starch powder into PLA is one of the most promising efforts because starch is an abundant and cheap biopolymer. However, the challenge is the major problem associated with poor interfacial adhesion between the hydrophilic starch granules and the hydrophobic PLA, leading to poorer mechanical properties. In this paper, soybean oil maleate (SOMA) was synthesized by grafting soybean oil with various weight percents of maleic anhydride (MA) using dicumyl peroxide (DCP) as an initiator. Then, SOMA was employed for the surface modifying of cassava starch powder, resulting in SOMA-g-STARCH. The obtained SOMA-g-STARCH was mixed with PLA in various weight ratios using twin-screw extruder, resulting in PLA/SOMA-g-STARCH. Finally, the obtained PLA/SOMA-g-STARCH composites were prepared by a compression molding machines. The compatibility, thermal properties, morphology properties, and mechanical properties were characterized and evaluated. The results showed that the compatibility, surface appearance, and mechanical properties at 90 : 10 and 80 : 20 ratios of PLA/SOMA-g-STARCH were the best. PMID:24307883

  17. Silver/poly (lactic acid) nanocomposites: preparation, characterization, and antibacterial activity

    PubMed Central

    Shameli, Kamyar; Ahmad, Mansor Bin; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa; Rahman, Russly Abdul; Jokar, Maryam; Darroudi, Majid

    2010-01-01

    In this study, antibacterial characteristic of silver/poly (lactic acid) nanocomposite (Ag/PLA-NC) films was investigated, while silver nanoparticles (Ag-NPs) were synthesized into biodegradable PLA via chemical reduction method in diphase solvent. Silver nitrate and sodium borohydride were respectively used as a silver precursor and reducing agent in the PLA, which acted as a polymeric matrix and stabilizer. Meanwhile, the properties of Ag/PLA-NCs were studied as a function of the Ag-NP weight percentages (8, 16, and 32 wt% respectively), in relation to the use of PLA. The morphology of the Ag/PLA-NC films and the distribution of the Ag-NPs were also characterized. The silver ions released from the Ag/PLA-NC films and their antibacterial activities were scrutinized. The antibacterial activities of the Ag/PLA-NC films were examined against Gram-negative bacteria (Escherichia coli and Vibrio parahaemolyticus) and Gram-positive bacteria (Staphylococcus aureus) by diffusion method using Muller–Hinton agar. The results indicated that Ag/PLA-NC films possessed a strong antibacterial activity with the increase in the percentage of Ag-NPs in the PLA. Thus, Ag/PLA-NC films can be used as an antibacterial scaffold for tissue engineering and medical application. PMID:20856832

  18. Poly(L-lactic acid) membranes: absence of genotoxic hazard and potential for drug delivery.

    PubMed

    Uzun, Nelson; Martins, Thomás Duzzi; Teixeira, Gabriella Machado; Cunha, Nayanne Larissa; Oliveira, Rogério Belle; Nassar, Eduardo José; Dos Santos, Raquel Alves

    2015-01-22

    The use of poly(L-lactic acid) (PLA) has been considered an important alternative for medical devices once this polyester presents biomechanical, optical and biodegradable properties. Moreover, the use of PLA results in less inflammatory reactions and more recently it has been proposed its application in drug delivery systems. Genotoxicological evaluations are considered part of the battery assays in toxicological analysis. Considering the wide applications of PLA, the present work evaluated the potential cytotoxic and genotoxic effects of PLA in CHO-K1 cells, as well as its physicochemical properties. No cytotoxic effects of PLA were detected by colorimetric tetrazolium assay (XTT) analysis, and the clonogenic survival assay showed that PLA did not disrupt the replicative cell homeostasis, neither exhibited genotoxic effects as evidenced by comet and micronucleus assays. Thermogravimetric properties of PLA were not altered after contact with cells and this film exhibited ability in absorb and release Europium(III) complex. All these data suggest genotoxicological safety of PLA for further applications in drug delivery systems.

  19. Mechanical, thermal and morphological properties of poly(lactic acid)/epoxidized palm olein blend.

    PubMed

    Silverajah, V S Giita; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Yunus, Wan Md Zin Wan; Hassan, Hazimah Abu

    2012-10-08

    Poly(lactic acid) (PLA) is known to be a useful material in substituting the conventional petroleum-based polymer used in packaging, due to its biodegradability and high mechanical strength. Despite the excellent properties of PLA, low flexibility has limited the application of this material. Thus, epoxidized palm olein (EPO) was incorporated into PLA at different loadings (1, 2, 3, 4 and 5 wt%) through the melt blending technique and the product was characterized. The addition of EPO resulted in a decrease in glass transition temperature and an increase of elongation-at-break, which indicates an increase in the PLA chain mobility. PLA/EPO blends also exhibited higher thermal stability than neat PLA. Further, the PLA/1 wt% EPO blend showed enhancement in the tensile, flexural and impact properties. This is due to improved interaction in the blend producing good compatible morphologies, which can be revealed by Scanning Electron Microscopy (SEM) analysis. Therefore, PLA can be efficiently plasticized by EPO and the feasibility of its use as flexible film for food packaging should be considered.

  20. Thermal property and assessment of biocompatibility of poly(lactic-co-glycolic) acid/graphene nanocomposites

    NASA Astrophysics Data System (ADS)

    Adhikari, Ananta R.; Rusakova, Irene; Haleh, Ardebili; Luisi, Jonathan; Panova, Neli I.; Laezza, Fernanda; Chu, Wei-Kan

    2014-02-01

    Polymer-matrix nanocomposites based on Poly(lactic-co-glycolic) acid (PLGA) and Graphene platelets (GNPs) were studied. GNPs, nanomaterials with a 2D flat surface, were chosen with or without chemical modification in PLGA/GNP nanocomposites and their microstructure, thermal property, and their compatibility as scaffolds for cell growth were investigated. PLGA/GNP nanocomposites (0, 1, and 5 wt. % of GNPs) were prepared using a solution based technique. Transmission electron microscopy, X-ray diffraction, Differential scanning calorimeter, and Thermogravimetric analyzer were used to analyze morphology and thermal properties. This work demonstrated the role of GNPs flat surface to provide a favorable platform resulting in an enhanced PLGA crystallization. Functionalized GNPs suppress both the thermal stability and the crystallization of PLGA. Finally, to determine the potential usefulness of these scaffolds for biomedical applications, mammalian cells were cultured on various PLGA/GNP nanocomposites (0, 1, and 5 wt. % GNPs). 1 wt. % PLGA/GNP nanocomposites showed better biocompatibility for cell growth with/without graphenes functionalization compared to pure PLGA and 5 wt. % PLGA/GNP. The function of GNPs in PLGA/GNPs (1 wt. %) composites is to provide a stage for PLGA crystallization where cell growth is favored. These results provide strong evidence for a new class of materials that could be important for biomedical applications.

  1. Poly (vinylsulfonic acid) assisted synthesis of aqueous solution stable vaterite calcium carbonate nanoparticles.

    PubMed

    Nagaraja, Ashvin T; Pradhan, Sulolit; McShane, Michael J

    2014-03-15

    Calcium carbonate nanoparticles of the vaterite polymorph were synthesized by combining CaCl2 and Na2CO3 in the presence of poly (vinylsulfonic acid) (PVSA). By studying the important experimental parameters we found that controlling PVSA concentration, reaction temperature, and order of reagent addition the particle size, monodispersity, and surface charge can be controlled. By increasing PVSA concentration or by decreasing temperature CCNPs with an average size from ≈150 to 500 nm could be produced. We believe the incorporation of PVSA into the reaction plays a dual role to (1) slow down the nucleation rate by sequestering calcium and to (2) stabilize the resulting CCNPs as the vaterite polymorph, preventing surface calcification or aggregation into microparticles. The obtained vaterite nanoparticles were found to maintain their crystal structure and surface charge after storage in aqueous buffer for at least 5 months. The aqueous stable vaterite nanoparticles could be a useful platform for the encapsulation of a large variety of biomolecules for drug delivery or as a sacrificial template toward capsule formation for biosensor applications.

  2. Efficient structural characterization of poly(methacrylic acid) by activated-electron photodetachment dissociation.

    PubMed

    Girod, Marion; Brunet, Claire; Antoine, Rodolphe; Lemoine, Jérôme; Dugourd, Philippe; Charles, Laurence

    2012-01-01

    Characterization of end-groups in poly(methacrylic acid) (PMAA) was achieved using tandem mass spectrometry after activated-electron photodetachment dissociation (activated-EPD). In this technique, multiply deprotonated PMAA oligomers produced in the negative-ion mode of electrospray ionization were oxidized into radical anions upon electron photodetachment using a 220 nm laser wavelength, and further activated by collision. In contrast to conventional collision induced dissociation of negatively charged PMAA, which mainly consists of multiple dehydration steps, fragmentation of odd-electron species is shown to proceed via a radical-induced decarboxylation, followed by reactions involving backbone bond cleavages, giving rise to product ions containing one or the other oligomer termination. A single radical-induced mechanism accounts for the four main fragment series observed in MS/MS. The relative position of the radical and of the anionic center in distonic precursor ions determines the nature of the reaction products. Experiments performed using PMAA sodium salts allowed us to account for relative abundances of product ions in series obtained from PMAA, revealing that ion stability is ensured by hydrogen bonds within pairs of MAA units.

  3. Promotion Effects of Ultra-High Molecular Weight Poly-γ-Glutamic Acid on Wound Healing.

    PubMed

    Choi, Jae-Chul; Uyama, Hiroshi; Lee, Chul-Hoon; Sung, Moon-Hee

    2015-06-01

    We examined the in vivo efficacy of ultra-high molecular weight poly-γ-glutamic acid (UHMW γ-PGA) for wound healing. The wound area was measured by a ruler and documented by digital photography before the animals were sacrificed at days 8 and 16 post wounding. The areas of wounds treated with UHMW γ-PGA were significantly decreased on days 8 and 16, as compared with those receiving a control treatment, and more than 70% of the UHMW γ-PGAtreated area was repaired by day 8. Hematoxylin and eosin staining confirmed that the epidermis had regenerated in the UHMW γ-PGA-treated wounds. At 16 days post wounding, collagen pigmentation and cross-linking were increased as compared with the control groups, and greater regeneration of blood vessels had occurred in UHMW γ-PGA-treated groups. Increased levels of transforming growth factor-beta and β-catenin were also observed in skin samples collected from UHMW γ-PGA-treated animals on days 8 and 16 post incision. Taken together, these findings suggest that UHMW γ-PGA promotes wound healing in vivo.

  4. Superhydrophobic poly(L-lactic acid) surface as potential bacterial colonization substrate

    PubMed Central

    2011-01-01

    Hydrophobicity is a very important surface property and there is a growing interest in the production and characterization of superhydrophobic surfaces. Accordingly, it was recently shown how to obtain a superhydrophobic surface using a simple and cost-effective method on a polymer named poly(L-lactic acid) (PLLA). To evaluate the ability of such material as a substrate for bacterial colonization, this work assessed the capability of different bacteria to colonize a biomimetic rough superhydrophobic (SH) PLLA surface and also a smooth hydrophobic (H) one. The interaction between these surfaces and bacteria with different morphologies and cell walls was studied using one strain of Staphylococcus aureus and one of Pseudomonas aeruginosa. Results showed that both bacterial strains colonized the surfaces tested, although significantly higher numbers of S. aureus cells were found on SH surfaces comparing to H ones. Moreover, scanning electron microscopy images showed an extracellular matrix produced by P. aeruginosa on SH PLLA surfaces, indicating that this bacterium is able to form a biofilm on such substratum. Bacterial removal through lotus leaf effect was also tested, being more efficient on H coupons than on SH PLLA ones. Overall, the results showed that SH PLLA surfaces can be used as a substrate for bacterial colonization and, thus, have an exceptional potential for biotechnology applications. PMID:22018163

  5. Sulfoacetic acid modifying poly(vinyl alcohol) hydrogel and its electroresponsive behavior under DC electric field

    NASA Astrophysics Data System (ADS)

    Xiang, Yu; Liu, Genqi; Zhang, Cheng; Liao, Jiae

    2013-01-01

    A strong electrolyte hydrogel was prepared by modifying poly (vinyl alcohol) hydrogel with sulfoacetic acid (SA-PVA). Its swelling properties, mechanical properties, and electroresponsive behavior in Na2SO4 solutions were studied. The results indicated that the water take-up ability of the hydrogel decreased with the increasing ionic strength of Na2SO4 solution. The Young’s modulus, elongation at break and tensile strength of the hydrogel swollen in deionized water are 1.247 MPa, 187% and 2.2 MPa, respectively. The hydrogel swollen in a Na2SO4 solution bent towards the cathode under non-contact dc electric fields, and its bending speed and equilibrium strain increased with increasing applied voltage. There is a critical ionic strength of 0.03 at which the maximum equilibrium strain of the hydrogel occurs. Also the bending behavior of hydrogel was not affected by the pH changes. By altering the direction of the applied potential cyclically, the hydrogel exhibited good reversible bending behavior. On this basis, a gel-worm was designed. Under a cyclically varying electric field (the period was 8 s, and the voltage ranged from -10 to 10 V), the walking speed was up to 15 cm min-1 in Na2SO4 solution with an ionic strength of 0.03.

  6. Retinal pigment epithelium cell culture on thin biodegradable poly(DL-lactic-co-glycolic acid) films.

    PubMed

    Lu, L; Garcia, C A; Mikos, A G

    1998-01-01

    Thin films of 50:50 and 75:25 poly(DL-lactic-co-glycolic acid) (PLGA) were manufactured with a controlled thickness of less than 10 microm. The effect of PLGA copolymer ratio on in vitro cell attachment, proliferation, morphology, and tight junction formation was evaluated using a human D407 retinal pigment epithelium (RPE) cell line. Almost complete cell attachment was achieved on both PLGA films after 8 h of cell seeding, which was comparable to that on tissue culture polystyrene (TCPS) controls. The initial cell seeding density affected attachment, and the optimal value for 50:50 PLGA was 25000 cells cm(-2). After 7 days of in vitro culture, cell density on 50:50 and 75:25 PLGA films increased 45 and 40 folds, respectively, and a 34-fold increase was observed on TCPS. The RPE cells cultured on PLGA films at confluence had a characteristic cobblestone morphology. Confluent RPE cells also developed normal tight junctions in vitro which were concentrated mainly at the apical surfaces of cell-cell junctions. These results demonstrated that thin biodegradable PLGA films can provide suitable substrates for human RPE cell culture, and may serve as temporary carriers for subretinal implantation of organized sheets of RPE.

  7. Bioactive poly(L-lactic acid) conduits seeded with Schwann cells for peripheral nerve regeneration.

    PubMed

    Evans, Gregory R D; Brandt, Keith; Katz, Steven; Chauvin, Priscilla; Otto, Lisa; Bogle, Melissa; Wang, Bao; Meszlenyi, Rudolph K; Lu, Lichun; Mikos, Antonios G; Patrick, Charles W

    2002-02-01

    This study attempted to enhance the efficacy of peripheral nerve regeneration using our previously tested poly(L-lactic acid) (PLLA) conduits by incorporating them with allogeneic Schwann cells (SCs). The SCs were harvested, cultured to obtain confluent monolayers and two concentrations (1 x 10(4) and 1 x 10(6) SC/ml) were combined with a collagen matrix (Vitrogen) and injected into the PLLA conduits. The conduits were then implanted into a 12 mm right sciatic nerve defect in rats. Three control groups were used: isografts, PLLA conduits filled with collagen alone and empty silicone tubes. The sciatic functional index (SFI) was calculated monthly through four months. At the end of second and fourth months, the gastrocnemius muscle was harvested and weighed for comparison and the graft conduit and distal nerve were harvested for histomorphologic analysis. The mean SFI demonstrated no group differences from isograft control. By four months, there was no significant difference in gastrocnemius muscle weight between the experimental groups compared to isograft controls. At four months, the distal nerve demonstrated a statistically lower number of axons mm2 for the high and low SC density groups and collagen control. The nerve fiber density was significantly lower in all of the groups compared to isograft controls by four months. The development of a "bioactive" nerve conduit using tissue engineering to replace autogenous nerve grafts offers a potential approach to improved patient care. Although equivalent nerve regeneration to autografts was not achieved, this study provides promising results for further investigation.

  8. Poly-γ-glutamic acid enhances the quality of recombant erythropoietin produced by CHO cells.

    PubMed

    Kim, Tae Gon; Cho, Young Chol; Chun, Bok-Hwan; Park, Sung Hyo; Lee, Hoi-Seon; Chung, Namhyun

    2014-03-04

    The effect of poly-γ-glutamic acid (γPGA), which is produced by Bacillus sp., on the production of recombinant erythropoietin (rEPO) by Chinese hamster ovary (CHO) cells in suspension culture was evaluated. The growth, viability, and productivity of recombinant CHO cells were investigated in a chemically defined medium with 50 and 500 kD γPGAs at 0.075% or with Pluronic F68. Cell growth with the two γPGAs was lower than that with Pluronic F68 but significantly higher than that without any additive (control). The effect of additives on rEPO productivity was 50 kDa γPGA > 500 kDa γPGA > Pluronic F68 > control. Using EPO-dependent F-36E cells, we found that the effect of additives on rEPO quality was 500 kDa γPGA > 50 kDa γPGA > control > Pluronic F68. γPGA has an enhancement effect on the quality of rEPO produced by CHO cells.

  9. Evaluation of poly (aspartic acid sodium salt) as a draw solute for forward osmosis.

    PubMed

    Gwak, Gimun; Jung, Bokyung; Han, Sungsoo; Hong, Seungkwan

    2015-09-01

    Poly (aspartic acid sodium salt) (PAspNa) was evaluated for its potential as a novel draw solute in forward osmosis (FO). The inherent advantages of PAspNa, such as good water solubility, high osmotic pressure, and nontoxicity, were first examined through a series of physicochemical analyses and atomic-scale molecular dynamics simulations. Then, lab-scale FO tests were performed to evaluate its suitability in practical processes. Compared to other conventional inorganic solutes, PAspNa showed comparable water flux but significantly lower reverse solute flux, demonstrating its suitability as a draw solute. Moreover, fouling experiments using synthetic wastewater as a feed solution demonstrated that PAspNa reversely flowed to the feed side reduced inorganic scaling on the membrane active layer. The recyclability of PAspNa was studied using both nanofiltration (NF) and membrane distillation (MD) processes, and the results exhibited its ease of recovery. This research reported the feasibility and applicability of FO-NF or FO-MD processes using PAspNa for wastewater reclamation and brackish water desalination.

  10. Adsorption of water vapor by poly(styrenesulfonic acid), sodium salt: isothermal and isobaric adsorption equilibria.

    PubMed

    Toribio, F; Bellat, J P; Nguyen, P H; Dupont, M

    2004-12-15

    Air conditioning and dehumidifying systems based on sorption on solids are of great interest, especially in humid climates, because they allow reduction of thermal loads and use of chlorofluorocarbons. Previous studies have shown that hydrophilic polymers such as sulfonic polymers can have very high performance in water adsorption from air. The aim of this study was to characterize the water vapor adsorption properties of fully sulfonated and monosulfonated poly(styrenesulfonic acid), sodium salt, and to elucidate the mechanism of adsorption on these materials. Adsorption isotherms have been determined by TGA between 298 and 317 K for pressures ranging from 0.1 to 45 hPa. They have type II of the IUPAC classification and a small hysteresis loop between adsorption and desorption processes was observed only for the monosulfonated sample. Water content is up to 80% weight at 80% relative humidity. Adsorption isotherms have been well fitted with the FHH model. Adsorption-desorption isobars have been determined by TGA under 37 hPa in the temperature range 298-373 K. They show that these polymers can be completely regenerated by heating at 313 K under humidified air. No degradation of the adsorption properties has been observed after several regenerations. Adsorption enthalpies and entropies have been deduced from the Clapeyron equation and from DSC measurements. A good agreement was found. A mechanism of adsorption is proposed considering two kinds of adsorbate: bounded water in electrostatic interaction with functional groups and free water resulting from condensation.

  11. Chitosan/poly-γ-glutamic acid nanoparticles improve the solubility of lutein.

    PubMed

    Hong, Da Young; Lee, Ji-Soo; Lee, Hyeon Gyu

    2016-04-01

    The aim of this study was to improve the solubility of lutein through the use of chitosan (CS)/poly-γ-glutamic acid (γ-PGA) nanoencapsulation. In terms of redispersibility, water-soluble chitosan (WsCS)/γ-PGA nanoparticles (NPs) were better than insoluble chitosan (InCS)/γ-PGA NPs. The lutein-loaded WsCS/γ-PGA NP has a spherical form with a size around 200nm and a narrow size distribution (PDI<0.1). Solubility measures showed that nanoencapsulation of lutein into WsCS/γ-PGA NPs resulted in a significant 12-fold higher solubility compared to that of non-nanoencapsulated lutein (p<0.05). The redispersibility index of the lutein-loaded NPs was 1.01, indicating that they were completely reconstituted into aqueous solution as same as original aqueous solution. These results suggest that WsCS/γ-PGA nanoencapsulation can be used to enhance the solubility of lutein and other poorly water-soluble compounds.

  12. Cadmium ion-doped magnetic poly(styrene-acrylic acid) nanospheres for sensitive electrochemical immunoassay.

    PubMed

    Zhang, Bing; Cui, Yuling; Liu, Bingqian; Chen, Huafeng; Chen, Guonan; Tang, Dianping

    2012-05-15

    A novel class of molecular tags, cadmium ion-doped magnetic poly(styrene-acrylic acid) nanospheres (Cd-MPSA), was first synthesized and functionalized with polyclonal rabbit anti-human luteinizing hormone antibodies (PAb(2)) for highly efficient electrochemical immunoassay of luteinizing hormone (LH). Transmission electron microscope (TEM) and Fourier transform infrared spectroscope (FTIR) were employed to characterize the prepared Cd-MPSA. By using Cd-MPSA-labeled PAb(2) as molecular tags, a novel sandwich-type immunoassay protocol was built for determination of LH on monoclonal mouse anti-human luteinizing hormone antibody (MAb(1))-functionalized gold electrode. The assay was carried out in pH 5.3 HAc-NaAc buffer solution by square wave voltammetry (SWV). The signal was obtained by the reduction of the doped cadmium ions in the Cd-MPSA. Under optimal conditions, the currents increased with the increasing LH level in the sample, and exhibited a linear range from 0.25 to 240 mIU mL(-1) with a detection limit of 0.08 mIU mL(-1) LH at 3s(B). The precision, reproducibility, and specificity were acceptable. No obvious difference was encountered in the analysis of spiking LH samples into newborn calf serum with the referenced values.

  13. Poly(lactic-co-glycolic) Acid/Solutol HS15-Based Nanoparticles for Docetaxel Delivery.

    PubMed

    Cho, Hyun-Jong; Park, Ju-Hwan; Kim, Dae-Duk; Yoon, In-Soo

    2016-02-01

    Docetaxel (DCT) is one of anti-mitotic chemotherapeutic agents and has been used for the treatment of gastric cancer as well as head and neck cancer, breast cancer and prostate cancer. Poly(lactic- co-glycolic) acid (PLGA) is one of representative biocompatible and biodegradable polymers, and polyoxyl 15 hydroxystearate (Solutol HS15) is a nonionic solubilizer and emulsifying agent. In this investigation, PLGA/Solutol HS15-based nanoparticles (NPs) for DCT delivery were fabricated by a modified emulsification-solvent evaporation method. PLGA/Solutol HS15/DCT NPs with about 169 nm of mean diameter, narrow size distribution, negative zeta potential, and spherical morphology were prepared. The results of solid-state studies revealed the successful dispersion of DCT in PLGA matrix and its amorphization during the preparation process of NPs. According to the result of in vitro release test, emulsifying property of Solutol HS15 seemed to contribute to the enhanced drug release from NPs at physiological pH. All these findings imply that developed PLGA/Solutol HS15-based NP can be a promising local anticancer drug delivery system for cancer therapy.

  14. Thermal property and assessment of biocompatibility of poly(lactic-co-glycolic) acid/graphene nanocomposites

    SciTech Connect

    Adhikari, Ananta R.; Rusakova, Irene; Chu, Wei-Kan; Haleh, Ardebili; Luisi, Jonathan; Panova, Neli I.; Laezza, Fernanda

    2014-02-07

    Polymer-matrix nanocomposites based on Poly(lactic-co-glycolic) acid (PLGA) and Graphene platelets (GNPs) were studied. GNPs, nanomaterials with a 2D flat surface, were chosen with or without chemical modification in PLGA/GNP nanocomposites and their microstructure, thermal property, and their compatibility as scaffolds for cell growth were investigated. PLGA/GNP nanocomposites (0, 1, and 5 wt. % of GNPs) were prepared using a solution based technique. Transmission electron microscopy, X-ray diffraction, Differential scanning calorimeter, and Thermogravimetric analyzer were used to analyze morphology and thermal properties. This work demonstrated the role of GNPs flat surface to provide a favorable platform resulting in an enhanced PLGA crystallization. Functionalized GNPs suppress both the thermal stability and the crystallization of PLGA. Finally, to determine the potential usefulness of these scaffolds for biomedical applications, mammalian cells were cultured on various PLGA/GNP nanocomposites (0, 1, and 5 wt. % GNPs). 1 wt. % PLGA/GNP nanocomposites showed better biocompatibility for cell growth with/without graphenes functionalization compared to pure PLGA and 5 wt. % PLGA/GNP. The function of GNPs in PLGA/GNPs (1 wt. %) composites is to provide a stage for PLGA crystallization where cell growth is favored. These results provide strong evidence for a new class of materials that could be important for biomedical applications.

  15. Transfer molding processes for nanoscale patterning of poly-L-lactic acid (PLLA) films

    NASA Astrophysics Data System (ADS)

    Dhakal, Rabin; Peer, Akshit; Biswas, Rana; Kim, Jaeyoun

    2016-03-01

    Nanoscale patterned structures composed of biomaterials exhibit great potential for the fabrication of functional biostructures. In this paper, we report cost-effective, rapid, and highly reproducible soft lithographic transfer-molding techniques for creating periodic micro- and nano-scale textures on poly (L-lactic acid) (PLLA) surface. These artificial textures can increase the overall surface area and change the release dynamics of the therapeutic agents coated on it. Specifically, we use the double replication technique in which the master pattern is first transferred to the PDMS mold and the pattern on PDMS is then transferred to the PLLA films through drop-casting as well as nano-imprinting. The ensuing comparison studies reveal that the drop-cast PLLA allows pattern transfer at higher levels of fidelity, enabling the realization of nano-hole and nano-cone arrays with pitch down to ~700 nm. The nano-patterned PLLA film was then coated with rapamycin to make it drug-eluting.

  16. Facial volume restoration of the aging face with poly-l-lactic acid.

    PubMed

    Fitzgerald, Rebecca; Vleggaar, Danny

    2011-01-01

    The purpose of this article is to discuss current techniques used with poly-l-lactic acid to safely and effectively address changes observed in the aging face. Several important points deserve mention. First, this unique agent is not a filler but a stimulator of the host's own collagen, which then acts to volumize tissue in a gradual, progressive, and predictable manner. The technical differences between the use of biostimulatory agents and replacement fillers are simple and straightforward, but are critically important to the safe and successful use of these products and will be reviewed in detail. Second, in addition to gains in technical insights that have improved our understanding of how to use the product to best advantage, where to use the product to best advantage in facial filling has also improved with ever-evolving insights into the changes observed in the aging face. Finally, it is important to recognize that a patient's final outcome, and the amount of product and work it will take to get there, is a reflection of the quality of tissues with which they start. This is, of course, an issue of patient selection and not product selection.

  17. Enhanced in vitro cell activity on silicon-doped vaterite/poly(lactic acid) composites.

    PubMed

    Obata, Akiko; Tokuda, Shingo; Kasuga, Toshihiro

    2009-01-01

    A biodegradable composite with silicon-species releasability was prepared using poly(l-lactic acid) (PLLA) and silicon-doped vaterite (SiV) particles. SiV with particle diameters of approximately 1 mum was prepared using aminopropyltriethoxysilane (APTES) as the silicon species by a carbonation process and then mixed with PLLA in methylene chloride according to a SiV to PLLA weight ratio of 1:2, resulting in the preparation of composite slurry. A composite film was prepared by dipping a cover glass in the slurry. The composite films were incubated in a culture medium for 7 days and the silicon concentration of the medium was measured to estimate the species releasability of the composites. A trace amount of silicon species was continuously released from the composites for 7 days, the amount depending on the content of APTES in SiV. On the composite releasing silicon species, mouse osteoblast-like cells (MC3T3-E1 cells) were significantly stimulated to proliferate and differentiate in comparison with those on a composite containing no silicon species. The proliferation of the cells on the composites releasing larger amounts of silicon species (0.51mgl(-1)day(-1)) was higher than that on the composites releasing smaller amount of the species (0.21mgl(-1)day(-1)). The silicon species in the composites were effective in enhancing the cellular functions. The composites were expected to be useful as a scaffold material for bone tissue engineering.

  18. Adsorption of α-amylase onto poly(acrylamide/maleic acid) hydrogels

    NASA Astrophysics Data System (ADS)

    Tümtürk, H.; Çaykara, T.; Şen, M.; Güven, O.

    1999-08-01

    Poly(acrylamide/maleic acid) [P(AAm/MA)] hydrogels were prepared by irradiating the ternary mixtures of AAm/MA and water by γ rays at ambient temperature. The influence of the MA on the adsorption of α-amylase, optimum working conditions and storage stability of enzyme were investigated. The adsorption capacity of hydrogels were found to increase from 0.40 to 0.71 mg α-amylase/g dry gel with increasing amount of MA in the gel system. Maximum enzyme activities were observed at lower pH values and higher temperatures for adsorbed enzyme compared with free enzyme. Kinetic parameters were calculated as 2.51 g/dm 3 for Km and 1.67×10 -3 g/dm 3 min for Vmax for free enzyme and in the range of 12.3-12.9 g/dm 3 for Km and 1.63×10 -3-1.96×10 -3 g/dm 3 min for Vmax depending on the amount of MA in the hydrogel. While, the enzymatic activity of free enzyme was completely lost after 20 days, adsorbed enzyme retained 47-59% of its original activity after 20 days, depending on the amount of MA in the hydrogels.

  19. Adsorption of α-amylase onto poly(N-vinyl 2-pyrrolidone/itaconic acid) hydrogels

    NASA Astrophysics Data System (ADS)

    Tümtürk, Hayrettin; Çaykara, Tuncer; Kantoǧlu, Ömer; Güven, Olgun

    1999-05-01

    α-Amylase enzyme was adsorbed on poly(N-vinyl 2-pyrrolidone/itaconic acid) (P(VP/IA)) hydrogels prepared by irradiating the ternary mixtures of VP/IA/water by γ-rays at ambient temperature. The adsorption capacity of the hydrogels was determined to increase from 2.30 to 3.40 mg α-amylase/g dry gel with increasing amount of IA in gel system. Kinetic parameters were calculated as 2.51 g/dm 3 for Km and 1.67 × 10 -3 g/dm 3 min for Vmax for free enzyme and in the range of 3.88-5.02 g/dm 3 for Km and 1.62 × 10 -3-2.27 × 10 -3 g/dm 3 min for Vmax depending on the amount of IA in the hydrogel. Enzyme activities were found to increase from 49.9% to 77.4% with increasing amount of IA in the gel system and retained their activities for one month storage. On the other hand, the free enzyme loses its activity completely after 20 days.

  20. Grafting of poly (lactic acid) with maleic anhydride using supercritical carbon dioxide

    NASA Astrophysics Data System (ADS)

    Khankrua, R.; Pivsa-Art, S.; Hiroyuki, H.; Suttiruengwong, S.

    2015-07-01

    The aim of this work was to modify poly lactic acid (PLA) via free radical grafting with maleic anhydride (MA) by using supercritical carbon dioxide (SCCO2). Benzoyl peroxide (BPO) was used as an initiator. The solubility of MA in SCCO2 was first determined to estimate the suitable grafting conditions and equilibrium. From the solubility study of MA in SCCO2, it was found that the solubility of MA in SCCO2 increased with the increasing pressure and dissolution time. PLA films were first prepared by compression molding. The ratio of MA to BPO was 2:1. The reaction temperature and pressure were 70°C and 100 bar respectively. The grafting reaction and the degree of grafting were characterized by nuclear magnetic resonance (NMR) spectroscopy and titration, respectively. Scanning electron microscope (SEM) technique and contact angle were used to confirm the changes in physical properties of PLA film grafted MA. NMR spectrum indicated that the grafting of MA onto PLA was successively achieved. Degree of grafting by using SCCO2 was as high as 0.98%. This provided rather high grafting degree compared with other processes. SEM pictures showed the rough surface structure on modified PLA film. In addition, contact angle results showed an improvement of the hydrophilicity by maleic anhydride grafting onto polymers.

  1. The visualisation of vitreous using surface modified poly(lactic-co-glycolic acid) microparticles.

    PubMed

    Chau, David Y S; Tint, Naing L; Collighan, Russell J; Griffin, Martin; Dua, Harminder S; Shakesheff, Kevin M; Rose, Felicity R A J

    2010-05-01

    AIMS To demonstrate the potential use of in vitro poly(lactic-co-glycolic acid) (PLGA) microparticles in comparison with triamcinolone suspension to aid visualisation of vitreous during anterior and posterior vitrectomy. METHODS PLGA microparticles (diameter 10-60 microm) were fabricated using single and/or double emulsion technique(s) and used untreated or following the surface adsorption of a protein (transglutaminase). Particle size, shape, morphology and surface topography were assessed using scanning electron microscopy (SEM) and compared with a standard triamcinolone suspension. The efficacy of these microparticles to enhance visualisation of vitreous against the triamcinolone suspension was assessed using an in vitro set-up exploiting porcine vitreous. RESULTS Unmodified PLGA microparticles failed to adequately adhere to porcine vitreous and were readily washed out by irrigation. In contrast, modified transglutaminase-coated PLGA microparticles demonstrated a significant improvement in adhesiveness and were comparable to a triamcinolone suspension in their ability to enhance the visualisation of vitreous. This adhesive behaviour also demonstrated selectivity by not binding to the corneal endothelium. CONCLUSION The use of transglutaminase-modified biodegradable PLGA microparticles represents a novel method of visualising vitreous and aiding vitrectomy. This method may provide a distinct alternative for the visualisation of vitreous whilst eliminating the pharmacological effects of triamcinolone acetonide suspension.

  2. Surfactants modify the release from tablets made of hydrophobically modified poly (acrylic acid)☆

    PubMed Central

    Knöös, Patrik; Onder, Sebla; Pedersen, Lina; Piculell, Lennart; Ulvenlund, Stefan; Wahlgren, Marie

    2013-01-01

    Many novel pharmaceutically active substances are characterized by a high hydrophobicity and a low water solubility, which present challenges for their delivery as drugs. Tablets made from cross-linked hydrophobically modified poly (acrylic acid) (CLHMPAA), commercially available as Pemulen™, have previously shown promising abilities to control the release of hydrophobic model substances. This study further investigates the possibility to use CLHMPAA in tablet formulations using ibuprofen as a model substance. Furthermore, surfactants were added to the dissolution medium in order to simulate the presence of bile salts in the intestine. The release of ibuprofen is strongly affected by the presence of surfactant and/or buffer in the dissolution medium, which affect both the behaviour of CLHMPAA and the swelling of the gel layer that surrounds the disintegrating tablets. Two mechanisms of tablet disintegration were observed under shear, namely conventional dissolution of a soluble tablet matrix and erosion of swollen insoluble gel particles from the tablet. The effects of surfactant in the surrounding medium can be circumvented by addition of surfactant to the tablet. With added surfactant, tablets that may be insusceptible to the differences in bile salt level between fasted or fed states have been produced, thus addressing a central problem in controlled delivery of hydrophobic drugs. In other words CLHMPAA is a potential candidate to be used in tablet formulations for controlled release with poorly soluble drugs. PMID:25755999

  3. Poly(lactic acid)/TiO₂ nanocomposites as alternative biocidal and antifungal materials.

    PubMed

    Fonseca, Carmen; Ochoa, Almudena; Ulloa, Maria Teresa; Alvarez, Eduardo; Canales, Daniel; Zapata, Paula A

    2015-12-01

    Poly(lactic acid) (PLA) composites with titanium oxide (TiO2) ~10-nm nanoparticles were produced by the melting process and their main properties were evaluated. The nanoparticles are homogeneously dispersed in the matrix with a low degree of agglomeration, as seen by transmission electron microscopy (TEM). The crystallinity temperature increased ~12% when 5 wt.% of TiO2 was added, showing that the nanoparticles acted as nucleating agents this trend was confirmed by optical images. The elastic modulus increased ~54% compared to neat PLA at 5 wt.% of nanoparticles. Despite these improvements, PLA/TiO2 nanocomposites showed lower shear viscosity than neat PLA, possibly reflecting degradation of the polymer due to the particles. Regarding biocidal properties, after 2h of contact the PLA/TiO2 composites with 8 wt.% TiO2 showed a reduction of Escherichia coli colonies of ~82% under no UVA irradiation compared to pure PLA. This biocidal characteristic can be increased under UVA irradiation, with nanocomposites containing 8 wt.% TiO2 killing 94% of the bacteria. The PLA/TiO2 nanocomposites with 8 wt.% were also 99.99% effective against Aspergillus fumigatus under the UVA irradiation.

  4. Preparation and characterization of microporous poly(D,L-lactic acid) film for tissue engineering scaffold.

    PubMed

    Shi, Shuai; Wang, Xiu Hong; Guo, Gang; Fan, Min; Huang, Mei Juan; Qian, Zhi Yong

    2010-11-24

    We prepared a series of microporous films based on poly(d,l-lactic acid) (PLA) via phase separation. According to scanning electron microscopy (SEM), a 3-dimensional foamy structure with multimicrometer scale pores on the air surface of film could be observed. As the morphology of PLA film could not be stabilized using solvent-nonsolvent phase separation, we investigated the effect of temperature, air movement, and concentration on the properties of microporous PLA films. The results show that when the temperature was 25°C in a vacuum, it was easy to prepare PLA film with micropores, and it was stable. As the relationship between the morphology and formation factors was clear and the morphology of the PLA film was controllable, we studied the PLA film's potential use for cell culture. SEM results showed that NIH3T3 cell could be adhered on the surface of film well after incubation for 2 days. Meanwhile, in vitro culture experiments revealed the great biocompatibility of the scaffold for adsorption and proliferation of fibroblasts.

  5. Poly(aspartic acid) with adjustable pH-dependent solubility.

    PubMed

    Németh, Csaba; Gyarmati, Benjámin; Abdullin, Timur; László, Krisztina; Szilágyi, András

    2017-02-01

    Poly(aspartic acid) (PASP) derivatives with adjustable pH-dependent solubility were synthesized and characterized to establish the relationship between their structure and solubility in order to predict their applicability as a basic material for enteric coatings. Polysuccinimide, the precursor of PASP, was modified with short chain alkylamines, and the residual succinimide rings were subsequently opened to prepare the corresponding PASP derivatives. Study of the effect of the type and concentration of the side groups on the pH-dependent solubility of PASP showed that solubility can be adjusted by proper selection of the chemical structure. The Henderson-Hasselbalch (HH) and the extended HH equations were used to describe the pH-dependent solubility of the polymers quantitatively. The estimate provided by the HH equation is poor, but an accurate description of the pH-dependent solubility can be found with the extended HH equation. The dissolution rate of a polymer film prepared from a selected PASP derivative was determined by fluorescence marking. The film dissolved rapidly when the pH was increased above its pKa. Cellular viability tests show that PASP derivatives are non-toxic to a human cell line. These polymers are thus of great interest as starting materials for enteric coatings.

  6. Isothermal crystallization kinetics of Poly (lactic acid) studied by ultrafast chip calorimeter

    NASA Astrophysics Data System (ADS)

    Jiang, Jing; Jiang, Wei; Huang, Zijie; Zhou, Dongshan; Xue, Gi

    2012-02-01

    Poly (lactic acid) (PLA) is a biocompatible, biodegradable polymer which has attracted much attention. The crystallization ability, as one of the most factors influencing the physical properties of the biomaterials such as thermal, mechanical, and biodegradable properties, has been widely studied mainly by differential scanning calorimeters. However, although the crystallization of PLA is relatively slow, it's difficult to avoid the crystallization from the nuclei or the structure reorganization of the metastable crystalline formed during the annealing process when we use the normal DSC with the heating rate on the level of tens of K/min. With the chip calorimeter whose scanning rate can go up to 1000 K/s, we can avoid the structure reorganization of metastable crystalline during the heating. In this case we annealed the PLA sample in the 80-120^oC temperature range and found the relationship between the onset the melting temperature Tm and crystallization temperature Tc is Tm= 0.53Tc+ 213.5 and the equilibrium melting temperature is Tm,f =179.6^oC.

  7. Biodegradability of poly(lactic-co-glycolic acid) after femtosecond laser irradiation

    PubMed Central

    Shibata, Akimichi; Yada, Shuhei; Terakawa, Mitsuhiro

    2016-01-01

    Biodegradation is a key property for biodegradable polymer-based tissue scaffolds because it can provide suitable space for cell growth as well as tailored sustainability depending on their role. Ultrashort pulsed lasers have been widely used for the precise processing of optically transparent materials, including biodegradable polymers. Here, we demonstrated the change in the biodegradation of a poly(lactic-co-glycolic acid) (PLGA) following irradiation with femtosecond laser pulses at different wavelengths. Microscopic observation as well as water absorption and mass change measurement revealed that the biodegradation of the PLGA varied significantly depending on the laser wavelength. There was a significant acceleration of the degradation rate upon 400 nm-laser irradiation, whereas 800 nm-laser irradiation did not induce a comparable degree of change. The X-ray photoelectron spectroscopy analysis indicated that laser pulses at the shorter wavelength dissociated the chemical bonds effectively, resulting in a higher degradation rate at an early stage of degradation. PMID:27301578

  8. A novel poly(acrylic acid-co-acrylamide)/diatomite composite flocculant with outstanding flocculation performance.

    PubMed

    Xu, Kun; Liu, Yao; Wang, Yang; Tan, Ying; Liang, Xuecheng; Lu, Cuige; Wang, Haiwei; Liu, Xiusheng; Wang, Pixin

    2015-01-01

    Series of anionic flocculants with outstanding flocculation performance, poly(acrylic acid-co-acrylamide)/diatomite composite flocculants (PAAD) were successfully prepared through aqueous solution copolymerization and applied to flocculate from oil-field fracturing waste-water. The structure of PAAD was characterized by Fourier transform infra-red spectroscopy, (13)C nuclear magnetic resonance and X-ray diffraction tests, and its properties were systematically evaluated by viscometer, thermogravimetry analysis and flocculation measurements. Furthermore, the influences of various reaction parameters on the apparent viscosity of flocculant solution were studied, and the optimum synthesis condition was determined. The novel composite flocculants exhibited outstanding flocculation properties. Specifically, the dosage of composite flocculants that could make the transmittance of treated wastewater exceed 90% was only approximately 12-35 ppm, which was far lower than that of conventional flocculants. Meanwhile, the settling time was lower than 5 s, which was similar to that of conventional flocculants. This was because PAAD flocculants had a higher absorption capacity, and larger chain extending space than conventional linear flocculants, which could refrain from the entanglement of linear polymer chains and significantly improve flocculation capacity.

  9. Poly(vinylphosphonic acid) (PVPA) on titanium alloy acting as effective cartilage-like superlubricity coatings.

    PubMed

    Zhang, Caixia; Liu, Yuhong; Wen, Shizhu; Wang, Song

    2014-10-22

    Poly(vinylphosphonic acid) (PVPA) is a type of hydrophilic polymer that can be used in surface modifications. In our study, PVPA coatings were formed on the surfaces of titanium alloy (Ti6Al4V) using a simple and novel method to achieve efficient lubrication at friction interfaces. The composition and 3D skeletal structure of the PVPA coatings were confirmed by X-ray photoelectron spectroscopy (XPS), focused ion beam/scanning electron microscopy (FIB/SEM), and solid-state nuclear magnetic resonance (NMR). The PVPA-modified Ti6Al4V/polytetrafluoroethylene (PTFE) interface shows a superlow friction coefficient (approximately 0.006) for at least 8 h under a contact pressure of 44.2 MPa (initial pressure), which means it falls into the superlubricity regime. Moreover, wear on the surfaces of both the Ti6Al4V and PTFE after the tribological experiment is superlow. It is proposed that the 3D skeletal structure of the PVPA coating and fluid-like manner at friction interfaces owing to the fast exchange of water molecules are the main factors accounting for the superlow friction and wear. The PVPA-modified Ti6Al4V has the potential uses in artificial cervical discs.

  10. Tailoring the morphology and crystallinity of poly(L-lactide acid) electrospun membranes

    PubMed Central

    Ribeiro, Clarisse; Sencadas, Vitor; Costa, Carlos Miguel; Gómez Ribelles, José Luís; Lanceros-Méndez, Senentxu

    2011-01-01

    Biodegradable poly(L-lactic acid) (PLLA) microfibers were prepared by electrospinning by varying the applied potential, solution flow rate and collector conditions. PLLA fibers with smoothly oriented and random morphologies were obtained and characterized by scanning electron microscopy. The optimum fiber orientation was obtained at 1000 rpm using a 20.3 cm diameter collecting drum, while for higher and lower drum rotation speeds, the rapid random motion of the jets resulted in a random fiber distribution. The deformation of the jet with rapid solidification during electrospinning often results in a metastable phase. PLLA electrospun fibers are amorphous but contain numerous crystal nuclei that rapidly grow when the sample is heated to 70–140 °C. In this way, the degree of crystallinity of the fibers can be tailored between 0 and 50% by annealing. Infrared transmission spectra revealed that the processing conditions do not affect the PLLA samples at the molecular level and that the crystallinity of the samples is related to the presence of α-crystals. PMID:27877378

  11. Effect of clay content on morphology and processability of electrospun keratin/poly(lactic acid) nanofiber.

    PubMed

    Isarankura Na Ayutthaya, Siriorn; Tanpichai, Supachok; Sangkhun, Weradesh; Wootthikanokkhan, Jatuphorn

    2016-04-01

    This research work has concerned the development of volatile organic compounds (VOCs) removal filters from biomaterials, based on keratin extracted from chicken feather waste and poly(lactic acid) (PLA) (50/50%w/w) blend. Clay (Na-montmorillonite) was also added to the blend solution prior to carrying out an electro-spinning process. The aim of this study was to investigate the effect of clay content on viscosity, conductivity, and morphology of the electrospun fibers. Scanning electron micrographs showed that smooth and bead-free fibers were obtained when clay content used was below 2 pph. XRD patterns of the electrospun fibers indicated that the clay was intercalated and exfoliated within the polymers matrix. Percentage crystallinity of keratin in the blend increased after adding the clay, as evidenced from FTIR spectra and DSC thermograms. Transmission electron micrographs revealed a kind of core-shell structure with clay being predominately resided within the keratin rich shell and at the interfacial region. Filtration performance of the electrospun keratin/PLA fibers, described in terms of pressure drop and its capability of removing methylene blue, were also explored. Overall, our results demonstrated that it was possible to improve process-ability, morphology and filtration efficiency of the electrospun keratin fibers by adding a suitable amount of clay.

  12. Tissue reactions to engineered cartilage based on poly-L-lactic acid scaffolds.

    PubMed

    Fujihara, Yuko; Asawa, Yukiyo; Takato, Tsuyoshi; Hoshi, Kazuto

    2009-07-01

    Tissue reactions against poly-L-lactic acid (PLLA) in engineered cartilage may influence the size or maturity of regenerative tissue. To understand the biological events in these reactions, we subcutaneously transplanted engineered constructs of PLLA scaffolds with or without human chondrocytes or atelocollagen in nude mice and evaluated neovascularization and macrophage activation, which can be assessed even in nude mice. Although not showing cartilage regeneration, PLLA alone demonstrated dense localization of macrophages and blood vessels, as well as a high level of interleukin-1 beta and tissue hemoglobin at 2 and 8 weeks. Otherwise, constructs with PLLA and chondrocytes with or without atelocollagen (PLLA/cell/gel or PLLA/cell) formed mature cartilage by 8 weeks, which was more prominent in PLLA/cell/gel. Although accumulation of macrophages and blood vessels in PLLA/cell/gel and PLLA/cell was comparable with that in PLLA at 2 weeks, that in PLLA/cell/gel markedly decreased by 8 weeks, with blood vessels and macrophages excluded into non-cartilage areas. Macrophage migration inhibitory factor could be involved in these suppressed tissue reactions, because it was expressed in chondrocytes of engineered cartilage. Intense tissue reactions inevitably occurred in biopolymers alone, but it is possible that maturation of engineered cartilage suppressed these reactions, which may contribute to circumventing deformity or malformation of engineered tissues.

  13. Novel hydrogels of chitosan and poly(vinyl alcohol)-g-glycolic acid copolymer with enhanced rheological properties.

    PubMed

    Lejardi, A; Hernández, R; Criado, M; Santos, Jose I; Etxeberria, A; Sarasua, J R; Mijangos, C

    2014-03-15

    Poly(vinyl alcohol) (PVA) has been grafted with glycolic acid (GL), a biodegradable hydroxyl acid to yield modified poly(vinyl alcohol) (PVAGL). The formation of hydrogels at pH = 6.8 and physiological temperature through blending chitosan (CS) and PVAGL at different concentrations has been investigated. FTIR, DOSY NMR and oscillatory rheology measurements have been carried out on CS/PVAGL hydrogels and the results have been compared to those obtained for CS/PVA hydrogels prepared under the same conditions. The experimental results point to an increase in the number of interactions between chitosan and PVAGL in polymer hydrogels prepared with modified PVA. The resulting materials with enhanced elastic properties and thixotropic behavior are potential candidates to be employed as injectable materials for biomedical applications.

  14. An Investigation of the Solid-State Condensation Polymerization Reaction in Vapor-Deposited Poly(amic acid)

    NASA Astrophysics Data System (ADS)

    Anthamatten, Mitchell; Letts, Stephan A.; Day, Katherine; Cook, Robert C.; Gies, Anthony P.; Nonidez, William K.

    2004-03-01

    The condensation polymerization reaction of 4,4'-oxydianiline (ODA) with pyromellitic dianhydride (PMDA) to form poly(amic acid) and the subsequent imidization reaction to form polyimide were investigated for films prepared using vapor deposition polymerization techniques. Fourier-transform infrared spectroscopy (FTIR), thermal analysis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of films prepared at different temperatures indicate that additional solid-state polymerization occurs prior to imidization reactions. Experiments suggest that poly(amic acid) oligomers form upon vapor-deposition and have a number-average molecular weights of about 1500 Daltons. Between 100-130 °C these chains undergo additional condensation reactions to form slightly higher molecular weight oligomers. This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

  15. Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites.

    PubMed

    Song, Cunfeng; Chang, Ying; Cheng, Ling; Xu, Yiting; Chen, Xiaoling; Zhang, Long; Zhong, Lina; Dai, Lizong

    2014-03-01

    A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates.

  16. Localized surface plasmon resonance interfaces coated with poly[3-(pyrrolyl)carboxylic acid] for histidine-tagged peptide sensing.

    PubMed

    Tighilt, Fatma-Zohra; Subramanian, Palaniappan; Belhaneche-Bensemra, Naima; Boukherroub, Rabah; Gabouze, Noureddine; Sam, Sabrina; Szunerits, Sabine

    2011-10-21

    The paper reports on a novel localized surface plasmon resonance (LSPR) substrate architecture for the immobilization and detection of histidine-tagged peptides. The LSPR interface consists of an ITO (indium tin oxide) substrate coated with gold nanostructures. The latter are obtained by thermal deposition of a thin (2 nm thick) gold film followed by post-annealing at 500 °C. The LSPR interface was coated with poly[3-(pyrrolyl)carboxylic acid] thin films using electrochemical means. The ability of the LSPR interfaces coated with poly[3-(pyrrolyl)carboxylic acid] to chelate copper ions was investigated. Once loaded with metal ions, the modified LSPR interface was able to bind specifically to histidine-tagged peptides. The binding process was followed using LSPR.

  17. Removal of dorzolamide from biomedical wastewaters with adsorption onto graphite oxide/poly(acrylic acid) grafted chitosan nanocomposite.

    PubMed

    Kyzas, George Z; Bikiaris, Dimitrios N; Seredych, Mykola; Bandosz, Teresa J; Deliyanni, Eleni A

    2014-01-01

    A novel graphite oxide/poly(acrylic acid) grafted chitosan nanocomposite (GO/CSA) was prepared and used as biosorbent for the removal of pharmaceutical compound (dorzolamide) from biomedical synthetic wastewaters. The performance was evaluated taking into account pH, kinetics and thermodynamics of adsorption. GO/CSA presented higher adsorption capacity in comparison with the parent materials (graphite oxide and poly(acrylic acid) grafted chitosan). All adsorbents prepared were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and potentiometric titration. The surface features were also evaluated after the dorzolamide adsorption in order to derive the adsorption mechanism. It was suggested that the reactive groups of GO and CSA can interact with the amino groups of dorzolamide and mainly the abundance of carboxyl groups of GO/CSA composite was the main reason for its enhanced adsorption capacity.

  18. The synthesis and in vitro characterization of the mucoadhesion and swelling of poly(acrylic acid) hydrogels.

    PubMed

    Warren, S J; Kellaway, I W

    1998-05-01

    The purpose of this research was to synthesize insoluble, mucoadhesive hydrogels by crosslinking linear poly(acrylic acid) with sucrose and investigate the relationship between hydrogel crosslink density, swelling, and in vitro mucoadhesion. A condensation reaction was employed to synthesize the hydrogels and crosslink density was varied by altering sucrose concentration and cure time. Equilibrium swelling at pH 7.4 was measured both gravimetrically and geometrically. In vitro mucoadhesion was determined by a tensile technique. Equilibrium swelling studies indicated that the crosslink density was proportional to both sucrose concentration and duration of cure time. In vitro mucoadhesive properties of the hydrogels improved as crosslink density increased. This was attributed to an increase in poly(acrylic acid) chain density/unit area of the equilibrium swollen hydrogel, which promoted interaction of the mucoadhesive and glycoprotein polymer chains.

  19. Improvement of holographic thermal stability in phenanthrenequinone-doped poly(methyl methacrylate-co-methacrylic acid) photopolymer

    NASA Astrophysics Data System (ADS)

    Yu, Dan; Liu, Hongpeng; Wang, Heng; Wang, Jian; Jiang, Yongyuan; Sun, Xiudong

    2011-08-01

    Experimental studies of holographic thermal stability in phenanthrenequinone (PQ)-doped poly(methyl methacrylate-co-methacrylic acid) [P(MMA-co-MAA)] photopolymers are presented. A possibility to improve the thermal stability of holograms is demonstrated by doping methacrylic acid (MAA) into the poly(methyl methacrylate) (PMMA) polymer matrix. MAA as a copolymerization monomer can form a more stable polymer matrix with methyl methacrylate (MMA) monomer and increase average molecular weight of photoproducts, which finally depress the diffusion of photoproduct. The optimized MAA concentration copolymerized into P(MMA-co-MAA) polymer matrix can bring nearly a month's lifetime of gratings, which is obviously an improvement over the usual PQ-PMMA material under thermal treatment.

  20. Poly lactic acid based foams prepared via thermally induced phase separation (TIPS): A method to tune the crystallinity

    NASA Astrophysics Data System (ADS)

    Pavia, Francesco Carfı; La Carrubba, Vincenzo; Brucato, Valerio

    2012-07-01

    Blends of Poly-L-Lactic Acid (PLLA) with two Poly-Lactic Acid (PLA) in different proportions (90/10 and 70/30) were utilized in order to produce biodegradable and biocompatible scaffolds for soft tissue engineering applications. The scaffolds were produced via thermally induced phase separation (TIPS) starting from ternary systems where dioxane was the solvent and water the non-solvent. Morphology was evaluated by Scanning Electron Microscopy (average pore size and interconnection). Moreover a DSC analysis was carried out on the as-obtained scaffold in order to obtain information about theirs thermal properties (enthalpy of melt and crystallization). The results showed that is possible to prepare scaffolds of PLLA/PLA via TIPS. Moreover, the PLA seems to influences the TIPS process in terms of demixing temperatures. The data confirm that the morphology and the mechanical properties of the scaffold can be tuned, starting from PLLA blends and using PLA with different molecular weights.