Browsing by Author "Krishna, AS"

Now showing 1 - 6 of 6
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    Calcium ion modulates protein release from chitosan-hyaluronic acid poly electrolyte gel
    (Poly. Eng. Sci., 2015-05) Krishna, AS; Radhakumary, C; Sreenivasan, K
    Polyelectrolyte complex (PEC) of chitosan (CH) and hyaluronic acid (HA) are widely used for skin, cartilage, and bone tissue engineering. However, no reports are seen on their response at high ionic media, like increased Ca21 where they are likely to be exposed in the form of bone constructs and the influence of these ions on modulating the release of incorporated entities such as drugs and growth factors. Here, we prepared freeze dried scaffolds of PEC of CH and HA (CH-HA) and characterized them by FTIR, TGA, SEM, and ESEM. FITC conjugated BSA, designated as FA, was incorporated into the PEC to study the release properties in response to Ca21. The swellability of CH-HA and the extent of drug release from the matrix, FA loaded CH-HA was studied in deionised water and aqueous Na1 and Ca21 solutions. Swelling and drug release were high for the matrix in aqueous Ca21 whereas it was remarkably low in water and Na1. Drug released was found to increase with concentrations of Ca21 (0.02–1.0M) indicating that CH-HA is a promising matrix for Ca21 responsive delivery of agents to accelerate healing of bone cracks, which is known to release high amount of Ca21.
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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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    Detection and imaging of fatty plaques in blood vessels using functionalized carbon dots
    (ANALYTICAL METHODS, 2015) Krishna, AS; Radhakumary, C; Sreenivasan, K
    The risk of developing atherosclerosis is proportional to the blood cholesterol level which in turn eventually leads to heart attack. Since a large number of asymptomatic young people have evidence of atherosclerosis, it is highly necessary to diagnose it at the earliest. This communication depicts a simple method to visualize cholesterol deposits using digitonin (DG) conjugated carbon dots (CDs). Physico-chemical characterization and preliminary blood compatibility evaluation of the functionalized CDs (CDDG) were successfully carried out. It is found that the probes could selectively bind cholesterol as evident from their ability to image cholesterol doped polymer films and tissues with heavy fatty plaques suspended in blood serum. An early visualization of cholesterol-rich plaques using fluorescent nanoprobes reported here may aid in the diagnosis of atherosclerosis and it seems that our finding may catalyze further developments in this imperative domain. The data that emerged from the study also indicate that the novel probe can be used for the selective detection of cholesterol in solution.
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    In vitro detection of calcium in bone by modified carbon dots
    (ANALYST, 2013) Krishna, AS; Radhakumary, C; Sreenivasan, K
    This article depicts a simple and novel approach to locate calcium deposits in bone using modified carbon dots (CDs) through fluorescence imaging. Amino-functionalized CDs along with glutamic acid, a naturally-occurring ligand for calcium ions, were conjugated onto hyaluronic acid using EDC chemistry. The ability of the probe to recognise Ca ions was demonstrated using polymer strips doped with Ca ions and freshly collected bones. The probe was found to bind more at bone cracks, reflecting its potential to locate micro-cracks in bone as well as to map Ca deposits. The bound portions can be visualized through a fluorescence microscope or by illumination by a UV source (365 nm). The components used to generate the probes, namely CD, glutamic acid and hyaluronic acid, are well known for their non-toxicity and biocompatibility. It appears, therefore, that the probe could be used for in vivo applications.
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    In vitro detection of calcium in bone by modified carbon dots.
    (Analyst., 2013-10) Krishna, AS; Radhakumary, C; Sreenivasan, K
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    Methotrexate anchored carbon dots as theranostic probes: digitonin conjugation enhances cellular uptake and cytotoxicity
    (RSC Advances, 2016-06) Krishna, AS; Radhakumary, C; Priya, SS; Ramesan, RM; Sreenivasan, K
    In recent years carbon dots (CDs) have been drawing increasing attention in the area of nano medicine. Their indubitable roles in cellular imaging, drug delivery and diagnosis are widely acknowledged. Digitonin (DG) has traditionally been known as a cell membrane permeabilizing agent. Based on this fact, we modified CDs with DG (CDDG) and further conjugated them with methotrexate (MX). This probe, CDDG conjugated MX (CDMX) was subjected to physico chemical characterization, cytotoxic evaluation via MTT assay and cellular uptake studies using confocal laser microscopy. The drug release study implied that at physiological pH, release is less reflecting maximum drug retention in the probe during circulation. The results which emerged have shown that DG is impacted in enhancing cellular uptake and cytotoxic potential of the drug carriers. The study indicates that theranostic probes with improved features can be generated from CDs by a judicious modification