Browsing by Author "Abraham, TE"

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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.