Browsing by Author "Dawlee, S"

Now showing 1 - 8 of 8
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    Development of segmented polyurethane elastomers with low iodine content exhibiting radiopacity and blood compatibility
    (BIOMEDICAL MATERIALS, 2011) Dawlee, S; Jayabalan, M
    Biofunctionally active and inherently radiopaque polymers are the emerging need for biomedical applications. Novel segmented polyurethane elastomer with inherent radiopacity was prepared using aliphatic chain extender 2,3-diiodo-2-butene-1,4-diol, polyol polytetramethylene glycol and 4,4'-methylenebis(phenyl isocyanate) (MDI) for blood compatible applications. Aliphatic polyurethane was also prepared using hexamethylene diisocyanate for comparison. X-ray analysis of the polyurethanes revealed good radiopacity even at a relatively low concentration of 3% iodine in aromatic polyurethane and 10% in aliphatic polyurethane. The polyurethanes also possessed excellent thermal stability. MDI-based polyurethane showed considerably higher tensile strength than the analogous HDI-based polyurethane. MDI-based aromatic polyurethane exhibited a dynamic surface morphology in aqueous medium, resulting in the segregation of hydrophilic domains which was more conducive to anti-thrombogenic properties. The polyurethane was cytocompatible with L929 fibroblast cells, non-hemolytic, and possessed good blood compatibility.
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    Development of segmented polyurethane elastomers with low iodine content exhibiting radiopacity and blood compatibility.
    (Biomedical materials (Bristol, England), 2011)
    Biofunctionally active and inherently radiopaque polymers are the emerging need for biomedical applications. Novel segmented polyurethane elastomer with inherent radiopacity was prepared using aliphatic chain extender 2,3-diiodo-2-butene-1,4-diol, polyol polytetramethylene glycol and 4,4'-methylenebis(phenyl isocyanate) (MDI) for blood compatible applications. Aliphatic polyurethane was also prepared using hexamethylene diisocyanate for comparison. X-ray analysis of the polyurethanes revealed good radiopacity even at a relatively low concentration of 3% iodine in aromatic polyurethane and 10% in aliphatic polyurethane. The polyurethanes also possessed excellent thermal stability. MDI-based polyurethane showed considerably higher tensile strength than the analogous HDI-based polyurethane. MDI-based aromatic polyurethane exhibited a dynamic surface morphology in aqueous medium, resulting in the segregation of hydrophilic domains which was more conducive to anti-thrombogenic properties. The polyurethane was cytocompatible with L929 fibroblast cells, non-hemolytic, and possessed good blood compatibility.
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    Intrinsically radiopaque polyurethanes with chain extender 4,4 '-isopropylidenebis [2-( 2,6-diiodophenoxy)ethanol] for biomedical applications
    (JOURNAL OF BIOMATERIALS APPLICATIONS, 2015) Dawlee, S; Jayabalan, M
    Radiopaque polyurethanes are used for medical applications as it allows post-operative assessment of the biomaterial devices using X-ray. Inherently, radiopaque polyurethanes based on polytetramethylene glycol (PTMG), polypropylene glycol, 4,4-methylenebis(phenyl isocyanate), and a new iodinated chain extender 4,4-isopropylidenebis[2-(2,6-diiodophenoxy)ethanol] with flexible spacers were synthesized and characterized. The iodinated polyurethanes were clear, optically transparent, and had high molecular weights. The polyurethanes also possessed excellent radiopacity and high thermal stability. The biocompatibility of the most promising iodinated polyurethane was evaluated both in vitro (cytotoxicity evaluation by direct contact and MTT assay, using L929 mouse fibroblast cells) and in vivo (toxicology studies in rabbits and subcutaneous implantation in rats). The material was nontoxic and well tolerated by the animals. Thus, these radiopaque and transparent polyurethanes are expected to have potential for various biomedical applications.
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    Iodinated glycidyl methacrylate copolymer as a radiopaque material for biomedical applications
    (JOURNAL OF BIOMATERIALS APPLICATIONS, 2013) Dawlee, S; Jayabalan, M
    Polymeric biomaterial was synthesized by copolymerizing 50:50 mol% of monomers, glycidyl methacrylate and methyl methacrylate. Iodine atoms were then grafted to the epoxide groups of glycidyl methacrylate units, rendering the copolymer radiopaque. The percentage weight of iodine in the present copolymer was found to be as high as 23%. The iodinated copolymer showed higher glass transition temperature and thermal stability in comparison with unmodified polymer. Radiographic analysis showed that the copolymer possessed excellent radiopacity. The iodinated copolymer was cytocompatible to L929 mouse fibroblast cells. The in vivo toxicological evaluation by intracutaneous reactivity test of the copolymer extracts has revealed that the material was nontoxic. Subcutaneous implantation of iodinated copolymer in rats has shown that the material was well tolerated. Upon explantation and histological examination, no hemorrhage, infection or necrosis was observed. The samples were found to be surrounded by a vascularized capsule consisting of connective tissue cells. The results indicate that the iodinated copolymer is biocompatible and may have suitable applications as implantable materials.
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    Oxidized chondroitin sulfate-cross-linked gelatin matrixes: A new class of hydrogels
    (BIOMACROMOLECULES, 2005)
    A naturally occurring glycosaminoglycan such as chondroitin-6-sulfate was first converted in to its aldehyde derivative by periodate oxidation and used as a cross-linking agent for gelatin giving rise to a new class of hydrogels. Cross-linking was predominantly due to Schiff's base formation between the c-amino groups of lysine or hydroxylysine side groups of gelatin and the aldehyde groups in oxidized chondroitin sulfate. The hydrogels were prepared from chondroitin sulfate with different degrees of oxidation and gelatin. They were characterized for degree of cross-linking, cross-linking density, equilibrium swelling, water vapor transmission rate, internal structure, and blood-compatibility. Degree of cross-linking of the gels determined by trinitrobenzene sulfonic acid assay showed that, the higher the degree of oxidation of the polysaccharide, the higher the degree of cross-linking. Examination of the internal structure by scanning electron microscopy showed that the hydrogels were highly porous in nature with interconnecting pores ranging from 50 to 200 mu m. Equilibrium swelling showed that the gels retained about 90% water and did not undergo dehydration rapidly. The hydrogels were nontoxic and blood-compatible. Since an important phase of early wound healing has been shown to involve secretion of glycosaminoglycans such as chondroitin sulfate by fibroblasts which form a hydrophilic matrix suitable for remodeling during healing, this new class of hydrogels prepared from chondroitin sulfate and gelatin without employing any extraneous cross-linking agents are expected to have potential as wound dressing materials.
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    Studies on inherently radiopaque acrylate copolymers for biomedical applications
    (JOURNAL OF APPLIED POLYMER SCIENCE, 2012) Dawlee, S; Jayabalan, M
    Poly(glycidyl methacrylate-co-ethyl methacrylate) and poly(glycidyl methacrylate-co-butyl methacrylate) random copolymers (with 5050 mol % of monomers) were made radiopaque by grafting iodine moieties through the ring opening reaction of the epoxy groups. The percentage weight of grafted iodine in the copolymers was found to be as high as 19%. The iodinated copolymers showed higher glass transition temperature and thermal stability in comparison with the parent copolymers. Iodinated copolymer of poly(glycidyl methacrylate-co-ethyl methacrylate) has improved glass transistion temperature than iodinated poly(glycidyl methacrylate-co-butyl methacrylate). Radiographic analysis of these iodinated copolymers showed excellent radiopacity. The in vitro cytotoxicity tests revealed cytocompatibility with cells. These radiopaque copolymers are expected to find application as dental and orthopedic cements. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
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    Studies on novel radiopaque methyl methacrylate: glycidyl methacrylate based polymer for biomedical applications
    (JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE, 2009) Dawlee, S; Jayakrishnan, A; Jayabalan, M
    A new class of radiopaque copolymer using methyl methacrylate (MMA) and glycidyl methacrylate (GMA) monomers was synthesized and characterized. The copolymer was made radiopaque by the epoxide ring opening of GMA using the catalyst o-phenylenediamine and the subsequent covalent attachment of elemental iodine. The copolymer was characterized by Fourier transform infrared (FTIR) spectra, energy dispersive X-ray analysis using environmental scanning electron microscope (EDAX), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). X-ray visibility of the copolymer was checked by X-radiography. Blood compatibility and cytotoxicity of the newly synthesized copolymer were also evaluated. The iodinated copolymer was thermally stable, blood compatible, non-cytotoxic, and highly radiopaque. The presence of bulky iodine group created a new copolymer with modified properties for potential use in biomedical applications.
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    Studies on novel radiopaque methyl methacrylate: glycidyl methacrylate based polymer for biomedical applications.
    (Journal of materials science. Materials in medicine, 2009)
    A new class of radiopaque copolymer using methyl methacrylate (MMA) and glycidyl methacrylate (GMA) monomers was synthesized and characterized. The copolymer was made radiopaque by the epoxide ring opening of GMA using the catalyst o-phenylenediamine and the subsequent covalent attachment of elemental iodine. The copolymer was characterized by Fourier transform infrared (FTIR) spectra, energy dispersive X-ray analysis using environmental scanning electron microscope (EDAX), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). X-ray visibility of the copolymer was checked by X-radiography. Blood compatibility and cytotoxicity of the newly synthesized copolymer were also evaluated. The iodinated copolymer was thermally stable, blood compatible, non-cytotoxic, and highly radiopaque. The presence of bulky iodine group created a new copolymer with modified properties for potential use in biomedical applications.