Browsing by Author "Nair, PA"

Now showing 1 - 9 of 9
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    Carbon dot based non enzymatic approach for the detection and estimation of glucose in blood serum
    (MATERIALS RESEARCH EXPRESS, 2016) Krishna, AS; Nair, PA; Radhakumary, C; Sreenivasan, K
    In this study we generated a simple, reliable and selective approach based on carbon dots (CDs) and 4-cyanophenylboronic acid (CPBA) for blood glucose sensing. The methodology relies on the quenching of the emission of CDs by CPBA followed by its recovery by glucose. The system consisting of CDs and CPBA was characterised by Fourier transform infra red spectrum, transmissions electron microscopic, dynamic light scattering instrument, UV-visible and fluorescence techniques. The response of the probe, CD-BA in presence of different concentrations of glucose was assessed. Linear range was obtained for glucose concentrations ranging from 1 to 30 mM. Interferences by other saccharides and various biomolecules coexisting in blood serum were negligible. The chemo sensor thus developed has been successfully used for the estimation of glucose in human blood serum. The system being sensitive, efficient and easy to perform is a promising platform for blood glucose sensing.
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    Electrospun biodegradable calcium containing poly(ester-urethane)urea: Synthesis, fabrication, in vitro degradation, and biocompatibility evaluation
    (JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A, 2013) Nair, PA; Ramesh, P
    In this work an in vitro degradable poly(ester-urethane)urea (PEUU) was synthesized using polycaprolactone diol, hexamethylene diisocyanate, and calcium salt of p-aminobenzoic acid. The synthesized polymer was characterized by 1H-NMR and FTIR spectroscopy and viscosity studies. Scaffolds having random micro fibrous structures were fabricated from PEUU by electrospinning process. The thermal properties of the scaffold were evaluated by thermogravimetric analysis and dynamic mechanical analysis. The mechanical property evaluation showed that the scaffold possess sufficiently high tensile strength of 16 MPa. The in vitro degradation studies of the electrospun scaffold were carried out in phosphate buffer saline for 6 months. The average mass loss of the scaffold after 6 months of hydrolytic degradation was 25%. FTIR spectroscopy study confirmed the degradation of the PEUU from decrease in intensity of 1400 cm1 peak corresponding to ionic carboxylate group. Presence of amine group and calcium ions in the degradation medium further confirmed the degradation of the hard segment in the hydrolytic medium. The mechanical property evaluation of the scaffold indicated a gradual decrease in tensile strength and modulus whereas percentage elongation of the scaffold increases with time of in vitro degradation. The morphological evaluation of the scaffold after degradation by SEM shows evidence of broken fibers and pores in the scaffold. Preliminary in vitro cytotoxicity test demonstrated that both the material and the degradation products were noncytotoxic in nature and the material showed good proliferation to L-929 cells. (c) 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
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    Non enzymatic colorimetric detection of glucose using cyanophenyl boronic acid included beta-cyclodextrin stabilized gold nanoparticles
    (ANALYTICAL METHODS, 2016) Nair, PA; Sreenivasan, K
    The selective recognition and estimation of glucose in biological fluids is important for the management of diabetes. Many non enzymatic methods have emerged to address the limitations of in use enzymatic approaches. Still, new techniques have been designed, considering the high demand for user friendly and cost effective methods. In this context, a colorimetric assay by the naked eye is widely appreciated as a simple protocol adaptable to the rural populations of third world countries. Herein we have adopted a "green" approach for the fabrication of a novel non-enzymatic glucose sensing method based on the inclusion of 4-cyanophenyl boronic acid (CPBA) with beta-cyclodextrin (beta-CD) stabilized gold nanoparticles (GNP). While CPBA has a good selectivity towards glucose, its solubility is low in aqueous media and this issue is taken care of by b-CD. The three component system is synthesized by a tandem one pot method and used as such for the selective and sensitive detection of glucose in an aqueous medium. We observed a gradual shift of the plasmon absorption peak and an observable color change from red to blue with the concentration of glucose. The concentration dependant color change was attributed to glucose mediated aggregation of the probes as revealed by the TEM analysis. The applicability of the method to a real biological matrix was evaluated by testing with human blood serum in the concentration range 1-20 mM. This sensing methodology, based on chemicals already available in the market and dodging complex chemistry, can be adapted for routine glucose estimation.
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    Synthesis and characterization of calcium-containing polyurethane using calcium lactate as a chain extender
    (POLYMER JOURNAL, 2012) Nair, PA; Ramesh, P
    In this study, a calcium-containing monomer, namely calcium lactate, was used for the synthesis of calcium-containing polyurethane for use in biomedical applications. Ether-based polyurethane was prepared using poly(oxytetramethylene) glycol, hexamethylene diisocyanate and calcium lactate. The prepared polymer was characterized by FTIR spectroscopy, which confirmed the presence of ionic linkages in the main chain. The thermal behavior, mechanical properties and viscosity of the polymer were studied, and the properties were compared with those of a control polyurethane sample without any metal. Because of ionic clustering in calcium lactate-incorporated ionic polyurethane, the mechanical properties and storage modulus were enhanced compared with those of nonionic polyurethane. The prepared calcium-containing polyurethane was evaluated for its blood compatibility. An evaluation of blood-material interactions revealed that the material is blood compatible and that the polymer does not induce any hemolysis. Polymer Journal (2012) 44, 1009-1014; doi:10.1038/pj.2012.51; published online 4 April 2012
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    Synthesis and Characterization of Poly(urethane-ether)s from Calcium Salt of p-Hydroxybenzoic Acid
    (JOURNAL OF APPLIED POLYMER SCIENCE, 2011) Nair, PA; Ramesh, P
    The synthesis and characterization of calcium-containing poly(urethane-ether)s, having ionic links in the main chain, is reported. Calcium salt of p-hydroxybenzoic acid (HBA-Ca) was prepared from p-hydroxybenzoic acid (HBA) and used as the chain extender in the preparation of calcium-containing poly(urethane-ether)s. Poly(urethane-ether)s, having two different compositions, were prepared by varying the mole ratios of poly(tetramethylene glycol), hexamethylene diisocyanate, and HBA-Ca. The synthesized poly(urethane-ether)s were characterized by infrared spectroscopy, thermogravimetric analysis, and dynamic mechanical analysis. The presence of calcium in the polymer chain was confirmed by energy-dispersive X-ray analysis. The inherent viscosity of metal-containing polymers decreased with the increase in the metal content of the polymer. The introduction of metal into the polymer lowers the thermal stability of the polymers as indicated by the decreased initial decomposition temperature. The glass transition temperature (T(g)) and the storage modulus of the metal-containing polymers increase with the increase in metal content presumably due to the formation of physical crosslink's in the polymer. From the mechanical studies of the polymer, it was observed that the metal-containing polymers exhibit high tensile strength and modulus. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 1946-1952, 2011
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    Synthesis, characterization and electrospinning of calcium containing polyurethane urea
    (Advances in Polymer Technology, 2015-11) Nair, PA; Ramesh, P
    Calcium-containing segmented polyurethane urea was synthesized using a calcium salt of p-aminobenzoic acid, polytetramethylene glycol, and 4,4′-methylene bis(cyclohexyl isocyanate) and thereafter fabricated into three-dimensional scaffolds for the use in biomedical applications. Biocompatibility evaluation of the polymer showed that this newly developed metal-containing polyurethane urea demonstrated good cytocompatibility and hemocompatibility. The fabricating ability of the metal-containing polymer was studied by the electrospinning process. The effect of various parameters such as polymer concentration, applied voltage, and flow rate on the electrospinning process, morphology, and diameter of the resultant fibers was investigated. The findings indicate that increasing the concentration and flow rate of the solution increases the fiber diameter. It was also demonstrated that increasing the applied voltage decreases the fiber diameter. Mechanical property evaluation of the scaffolds showed that the strength of the scaffold depends on both the diameter and morphology of the fibers. As the fiber diameter increases from 1.6 to 3.02 μm, the tensile strength enhanced from 3 to 7 MPa.
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    Synthesis, Characterization, and Electrospinning of Calcium-Containing Polyurethane Urea
    (ADVANCES IN POLYMER TECHNOLOGY, 2016) Nair, PA; Parameswaran, R
    Calcium-containing segmented polyurethane urea was synthesized using a calcium salt of p-aminobenzoic acid, polytetramethylene glycol, and 4,4-methylene bis(cyclohexyl isocyanate) and thereafter fabricated into three-dimensional scaffolds for the use in biomedical applications. Biocompatibility evaluation of the polymer showed that this newly developed metal-containing polyurethane urea demonstrated good cytocompatibility and hemocompatibility. The fabricating ability of the metal-containing polymer was studied by the electrospinning process. The effect of various parameters such as polymer concentration, applied voltage, and flow rate on the electrospinning process, morphology, and diameter of the resultant fibers was investigated. The findings indicate that increasing the concentration and flow rate of the solution increases the fiber diameter. It was also demonstrated that increasing the applied voltage decreases the fiber diameter. Mechanical property evaluation of the scaffolds showed that the strength of the scaffold depends on both the diameter and morphology of the fibers. As the fiber diameter increases from 1.6 to 3.02 m, the tensile strength enhanced from 3 to 7MPa.