Browsing by Author "Kiran, S"

Now showing 1 - 5 of 5
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    Inherently X-ray opaque polyurethane microspheres for biomedical applications
    (INTERNATIONAL JOURNAL OF POLYMERIC MATERIALS AND POLYMERIC BIOMATERIALS, 2017) Kiran, S; Sunny, MC; Joseph, R
    In this work synthesis and characterization of inherently X-ray opaque, nonresorbable polyurethane microspheres with well-calibrated particles in a defined range of sizes suitable for embolization is reported. In order to impart X-ray opacity to the polyurethane, a bifunctional monomer, namely, 4,4-isopropylidenediphenol (BPA) was iodinated and this iodinated compound was used as one of the monomers during polyurethane synthesis. The resultant X-ray opaque polyurethane was converted into microspheres using an oil-in-water emulsion and solvent evaporation technique. Microspheres obtained had diameters in the range of 200-500 mu m, were noncytotoxic and free from X-ray attenuating additives. In vivo X-ray fluoroscopic imaging carried out in a rabbit cadaver model showed that these microspheres were sufficiently X-ray opaque to be visualized under fluoroscopic conditions. [GRAPHICS] .
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    Polyurethane thermoplastic elastomers with inherent radiopacity for biomedical applications
    (JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A, 2012) Kiran, S; James, NR; Jayakrishnan, A; Joseph, R
    Synthesis and characterization of three different radiopaque thermoplastic polyurethane elastomers are reported. Radiopacity was introduced to the polyurethanes by incorporating an iodinated chain extender, namely, 4,4'-isopropylidinedi-(2,6-diiodophenol) (IBPA), into the polymer chain during polyurethane synthesis. Radiopaque polyurethanes (RPUs) were synthesized by reacting 4,4'-methylenebis(phenyl isocyanate) (MDI), IBPA, and three different diols. The polyols used for the synthesis were polypropylene glycol, polycaprolactone diol, and poly(hexamethylene carbonate) diol. RPUs were characterized by infrared spectroscopy, contact angle measurements, thermogravimetry, dynamic mechanical analysis, energy dispersive X-ray analysis, gel permeation chromatography, X-ray fluorescence spectroscopy, and X-radiography. X-ray images showed that all RPUs prepared using IBPA as the chain extender are highly radiopaque compared with an Aluminum wedge of equivalent thickness. Elemental analysis revealed that the polyurethanes contained 1819% iodine in the polymer matrix. The RPUs developed have radiopacity equivalent to that of a polymer filled with 20 wt % barium sulfate. Results revealed that RPUs of wide range of properties may be produced by incorporating different diols as the soft chain segment. Cell culture cytotoxicity studies conducted using L929 cells by direct contact test and MTT assay proved that these RPUs are noncytotoxic in nature. (c) 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2012.
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    Synthesis and characterization of a noncytotoxic, X-ray opaque polyurethane containing iodinated hydroquinone bis(2-hydroxyethyl) ether as chain extender for biomedical applications
    (JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A, 2014) Kiran, S; Joseph, R
    An iodinated urethane polymer that does not require addition of X-ray attenuating additives to impart Xray opacity was synthesized and characterized for biomedical applications. A new X-ray opaque diiodo compound, namely, 2,2'-(2,5-diiodobenzene-1,4-diyl)bis(oxy)diethanol (DBD), was synthesized by iodinating hydroquinone bis(2-hydroxyethyl) ether and this compound was used as chain extender during polyurethane synthesis so that X-ray opacity could be imparted to the polymer formed. X-ray opaque polyurethane (XPU) was synthesized by reacting 1,6-diisocyanatohexane with poly(hexamethylene carbonate) diol and DBD. X-ray opacity of XPU was measured with a fluoroscopy machine using BaSO4-filled polyurethane as controls. Radiographic images showed that XPU sample had X-ray opacity equivalent to 15 wt % BaSO4-filled polymer. In vivo imaging in a rabbit model showed that the material could be readily distinguishable from bones. XPU was found to be hemocompatible and noncytotoxic to L929 fibroblast cell lines. Optical transparency measurements using ultraviolet-visible spectrophotometer showed that XPU transmitted 85% of visible light. (C) 2013 Wiley Periodicals, Inc.
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    Synthesis and characterization of X-ray opaque polycarbonate urethane: Effect of a dihalogenated chain extender on radiopacity and hemocompatibility
    (Journal of Biomedical Materials Research Part A., 2014-10) Kiran, S; Joseph, R
    An inherently radiopaque poly(carbonate urethane) containing fluorine and iodine atoms in the polymer chain was synthesized and characterized. Radiopaque polyurethane was synthesized from 1,6-diisocyanatohexane (HDI), poly (hexamethylene carbonate)diol (PHCD) and a newly synthesized chain extender having fluorine and iodine in the molecule, namely, 4,4'-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)bis(2,6-diiodophenol) (IBAF). IBAF monomer imparted radiopacity and improved the hemocompatibility of the resultant polymer. For comparative evaluation, polyurethanes (PU) were synthesized by reacting monomers HDI and PHCD without any chain extender and also by reacting HDI and PHCD along with noniodinated, but fluorine containing, version of the above chain extender, namely, 4,4'-(Hexafluoroisopropylidene) diphenol (BAF). Chain extended PUs showed improved mechanical and thermal properties, and hemocompatibility compared to the nonchain extended PU. Radiopacity measurements by fluoroscopy showed that IBAF incorporated PU of 200 µm thickness had radiopacity equivalent to that of 25% barium sulfate filled noniodinated PU of same thickness and to that of 0.6-mm thick aluminum wedge. In vivo imaging using a rabbit cadaver model showed clearly distinguishable image of IBAF incorporated PU sample. All the PU materials were noncytotoxic to L929 mouse fibroblast cells. Preliminary results obtained from blood-material interaction studies showed that incorporation of fluorinated chain extenders in the PUs resulted in significant reduction in the adhesion of white blood cells onto the PU material surface and also resulted in prolonged partial thromboplastin time. Results suggest that incorporation of fluorine and iodine containing chain extenders would lead to the development PU with improved hemocompatibility and radiopacity