Browsing by Author "Pillai, CKS"

Now showing 1 - 7 of 7
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    Challenges for Natural Monomers and Polymers: Novel Design Strategies and Engineering to Develop Advanced Polymers
    (DESIGNED MONOMERS AND POLYMERS, 2010) Pillai, CKS
    The last century witnessed the emergence of polymer science and technology that enabled the generation of knowledge and techniques to control the size, shape, structure, properties and functions of polymers to generate polymers with unprecedented properties and functions. There have been many attempts to apply this information to natural monomers and polymers to achieve the desired property profiles with varying degrees of success which have given/are giving it a new outlook as a possible alternative source for the production of polymers. Novel concepts and techniques such as 'bio-inspired' polymer design, 'synthetically-inspired' material development, etc., are contributing to the development of natural monomers and polymers as a sustainable resource to generate a knowledge-based design methodology to meet the vastly developing requirements of modern materials. This paper reviews these emerging concepts and techniques that integrate materials synthesis, process and manufacturing options with eco efficiency. (c) Koninklijke Brill NV, Leiden, 2010
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    Chitin and chitosan polymers: Chemistry, solubility and fiber formation
    (PROGRESS IN POLYMER SCIENCE, 2009) Pillai, CKS; Paul, W; Sharma, CP
    Chitin and chitosan (CS) are biopolymers having immense structural possibilities for chemical and mechanical modifications to generate novel properties, functions and applications especially in biomedical area. Despite its huge availability, the utilization of chitin has been restricted by its intractability and insolubility. The fact that chitin is as an effective material for sutures essentially because of its biocompatibility, biodegradability and non-toxicity together with its antimicrobial activity and low immunogenicity, points to immense potential for future development. This review discusses the various attempts reported on solving this problem from the point of view of the chemistry and the structure of these polymers highlighting the drawbacks and advantages of each method and proposes that based on considerations of structure-property relations, it is possible to obtain chitin fibers with improved strength by making use of their nanostructures and/or mesophase properties of chitin. (C) 2009 Elsevier Ltd. All rights reserved.
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    Folic acid-conjugated depolymerized quaternized chitosan as potential targeted gene delivery vector
    (POLYMER INTERNATIONAL, 2011) Morris, VB; Pillai, CKS; Sharma, CP
    Ligand-conjugated delivery vectors that target over-expressed cell surface receptors have a potential impact on gene therapy. In the study reported, high-molecular-weight chitosan was depolymerized to medium and low molecular weight and trimethylated to render the polymer soluble over a wider pH range. Folate conjugation was introduced to the quartemized derivative to improve gene transfection efficiency. Complexes of the folic acid-conjugated trimethylated depolymerized chitosan (FTMC) with plasmid DNA (pDNA) formed core-shell nanostructured particles. Gel electrophoretic band retardation showed efficient condensation of DNA. These derivatives and their complexes with pDNA were tested for toxicity and haemocompatibility and were found to be significantly less toxic and haemocompatible than polyethyleneimine. Transfection efficiency and nuclear uptake properties were tested in the human KB oral epidermoid cell line, which over-expresses the folate receptor in the presence of 10% serum. Among the four FTMC derivatives investigated, folic acid-conjugated chitosan having low molecular weight and medium folate conjugation was found to be a potential vector for gene delivery applications with good transfection and nuclear uptake properties, as proved by YOYO labelling of pDNA. (C) 2011 Society of Chemical Industry
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    Liquid crystalline phase behavior of high molecular weight DNA: A comparative study of the influence of metal ions of different size, charge and binding mode
    (BIOMACROMOLECULES, 2008) Sundaresan, N; Suresh, CH; Thomas, T; Thomas, TJ; Pillai, CKS
    The ability of Li+, Na+, K+, Rb+, CS+, Mg2+, Ca2+, Sr2+, Ba2+, Cu2+, Cd2+, Al3+, V4+, Hg2+, Pd2+, Au3+, and Pt4+ to provoke liquid crystalline (LC) phases in high molecular weight DNA was investigated. The alkali and alkaline earth metal ions provoked typical cholesteric/columnar structures, whereas transition metal ions precipitated DNA into solid/translucent gel-like aggregates. Heavy metal ions reduced viscosity of DNA solution, disrupting rigid, rod-like DNA structure necessary for LC textures. Three-layer quantum mechanical-molecular mechanical (QM/MM) studies of Li+, Na+, K+, Mg2+, and Ca2+ binding DNA fragment suggested several possible binding modes of these ions to the phosphate groups. The dianion mode of metal binding, involving the phosphate groups of both strands of DNA, allowed for higher DNA binding affinity of the alkaline earth metal ions. These results have implications in understanding the biological role of metal ions and developing DNA-based sensors and nanoelectronic devices.
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    Semiflexible random thermotropic copolymers from 8-(3-hydroxy phenyl) octanoic acid and 3-chloro-4-hydroxy benzoic acid/3,5-dibromo-4-hydroxy benzoic acid
    (JOURNAL OF APPLIED POLYMER SCIENCE, 2008) Mitra, S; Pillai, CKS
    Two series of semiflexible random thermotropic copolymers containing 8-(3-hydroxy phenyl) octanoic acid (HPOA) with either 3-chloro-4-hydroxy benzoic acid or 3,5-dibromo-4-hydroxy benzoic acid were prepared by melt polycondensation techniques. The copolyesters were characterized with Fourier transform infrared spectroscopy, dilute solution viscometry, hot-stage polarized light microscopy, differential scanning calorimetry, thermogravimetric analysis, and wide-angle X-ray diffraction. Studies revealed that the amount of HPOA as a disruptor incorporated into the backbone of substituted 4-hydroxy benzoic acids had a detrimental effect on the liquid-crystalline behavior. Mesophase-transition temperatures were observed between 210 and 250 degrees C, and the optical textures were of typical nematic phases. The degree of crystallinity decreased with an increase in the HPOA content. The thermal stability of the copolymers was in the range of 310-370 degrees C. (C) 2007 Wiley Periodicals, Inc.
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    Studies on the Condensation of Depolymerized Chitosans With DNA for Preparing Chitosan-DNA Nanoparticles for Gene Delivery Applications
    (JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS, 2009) Morris, VB; Neethu, S; Abraham, TE; Pillai, CKS; Sharma, CP
    High molecular weight chitosan (CS) was depolymerized by oxidative degradation with NaNO(2) at room temperature to get 11 samples of CS derivatives of varying molecular weights with a view to assessing their effective molecular weight range for gene delivery applications. Viscosity studies indicated that the molecular weight of the depolymerized CS was proportional to the CS/NaNO(2) ratio. The condensation behavior of DNA/CS complexes at various charge ratios was studied using UV spectroscopy, FTIR, CD, SEM, and AFM. The results indicated that CSs having very low molecular weights and high charge density exhibited strong binding affinity to DNA compared to high molecular weight CSs. However, the very low molecular weight (1.9-7.7 kDa) CSs were found to form aggregates easily even at very low charge ratios. On the other hand, CSs having medium molecular weight (49-51 kDa) and high degree of deacetylation (DD) gave stable uniform-sized nanoparticles. Biological studies carried out with the spherical nano-sized polyplexes formed between CS of 50 kDa (DD of 94%) and pEGFP plasmid DNA at NIP ratio of 5.0 showed excellent gene transfection efficiency at pH 6.5 in HeLa cells without cytotoxicity indicating their potential as gene delivery carriers. (C) 2008 Wiley Periodicals. Inc. J Biomed Mater Res Part 13: Appl Biomater 89B: 282-292,2009
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    Synthesis and characterization of novel water-soluble polyamide based on spermine and aspartic acid as a potential gene delivery vehicle
    (EXPRESS POLYMER LETTERS, 2008) Viola, BM; Abraham, TE; Arathi, DS; Sreekumar, E; Pillai, MR; Thomas, TJ; Pillai, CKS
    We developed a novel and convenient method for the synthesis of a potentially safe non-viral gene delivery vehicle based on the cationic block copolymer of spermine and aspartic acid ( ASSP) and coupled it with polyethylene glycol (PEG). The copolymer ASSP was prepared by direct polycondensation in the ionic liquid, butylmethylimidazolium hexafluorophosphate, using triphenyl phosphite as the condensing agent under mild reaction conditions. The highly hydrophobic ASSP was transformed into a water soluble hydrophilic micelle by coupling ASSP with polyethylene glycol (PEG) using the same ionic liquid and 1,1-carbonyl diimidazole as the condensing agent without harsh conditions. The polycationic ASSP-PEG was then used to condense calf thymus and plasmid deoxyribonuclceic acids (DNAs) in Tris-HCl buffer (pH 7.4) to get a series of block ionomer complexes with various charge ratios. The physicochemical properties of the copolymer micelle and the DNA polyplexes were studied using fourier transform-infrared (FTIR), nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopy, matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS), differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and particle size measurements. It was observed that the DNA was condensed to compact particles by its interaction with the copolymer. Since DNA condensation to nano/micrometer sized particles is essential for gene delivery, our results indicate a potential use of the copolymer for gene delivery applications.