Uma Maheswari Krishnan

SASTRA University, Tanjor, Tamil Nadu, India

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Publications (112)371.24 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A hybrid interface was developed using nano iron oxide and carbon nanotubes and this architecture offered an improved performance for the detection of hydrogen peroxide. Nano iron oxide was synthesized by a simple thermal co-precipitation technique and it was dispersed in nafionic solution. To this mixture added the catalase enzyme adsorbed multi-walled carbon nanotubes and this solution was used for the modification of the electrode. The morphology of the prepared nanocomposite was observed using FE-TEM and the electrochemical studies were carried out using cyclic voltammetry and amperometry. The linear range of the prepared amperometric sensor was found to be between 1.2 and 21.6 μM with a quick response time of less than 1 s. The interference, reproducibility and stability studies were carried out with satisfactory results. The limit of detection and limit of quantification were found to be 3.7 nM and 12.2 nM respectively. With the convincing results obtained in terms of the performance of the biosensor, this platform was successfully upgraded for the determination of hydrogen peroxide in the presence of milk samples.
    Sensors and Actuators B Chemical 08/2015; 215. DOI:10.1016/j.snb.2015.03.041 · 3.84 Impact Factor
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    ABSTRACT: Most of the metal ions are carcinogens and lead to serious health concerns by producing free radicals. Hence, fast and accurate detection of metal ions has become a critical issue. Among various metal ions arsenic, cadmium, lead, mercury and chromium are considered to be highly toxic. To detect these metal ions, electrochemical biosensors with interfaces such as microorganisms, enzymes, microspheres, nano-materials like gold, silver nanoparticles, CNTs, and metal oxides have been developed. Among these, nanomaterials are considered to be most promising, owing to their strong adsorption, fast electron transfer kinetics, and biocompatibility, which are very apt for biosensing applications. The coupling of electrochemical techniques with nanomaterials has enhanced the sensitivity, limit of detection, and robustness of the sensors. In this review, toxicity mechanisms of various metal ions and their relationship towards the induction of oxidative stress have been summarized. Also, electrochemical biosensors employed in the detection of metal ions with various interfaces have been highlighted.
    Sensors and Actuators B Chemical 07/2015; 213:515-533. DOI:10.1016/j.snb.2015.02.122 · 3.84 Impact Factor
  • Sathya Narayanan Vijayakumar, Swaminathan Sethuraman, Uma Maheswari maheswari Krishnan
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    ABSTRACT: Proliferation and self-sufficiency are two most important properties of cancer cells. Although genetic aberrations are believed to be the reason for cancer development, importance of metabolic alterations in cancer development have found the lime light lately. The most challenging aspect in cancer treatment has been their similarity to host cells. The discovery of various metabolic alterations that occur in cancers to attain and maintain proliferative state has resulted in new information on the metabolic differences between normal and cancer cells. One such alteration is the establishment of Warburg effect. This review elaborates on various changes that lead to establishment of Warburg effect in cancer cells and their consequences. Understanding the metabolic uniqueness of various cancers can aid in identification of novel molecular targets leading to more efficient strategies in cancer treatment.
    RSC Advances 04/2015; 5(52). DOI:10.1039/C5RA06505D · 3.71 Impact Factor
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    ABSTRACT: The presence of captan residues in apples shows high toxicity, which often causes eye and skin irritation, dermatitis, conjunctivitis, and vomiting in humans. In this context, an electrochemical biosensor based on acetylcholinesterase (AChE) immobilized on a ZnO nanorod interface has been proposed. In this work, Hill, dose-response, and first-, second-, and third-order polynomial regression models were successfully applied and the prediction ability of these models was tested with the use of current density obtained from the cyclic voltammograms of appropriate captan solutions. The Pt/ZnO/AChE bioelectrode showed a high sensitivity of 0.538 μA cm(-2) μM(-1) in the linear range from 0.05 to 25.0 μM with a limit of detection of 107 nM. The recovery results were observed between 98.4 and 102.4 % from the apple sample. This work provides a new promising tool for the detection of captan in apple samples.
    Analytical and Bioanalytical Chemistry 04/2015; 407(16). DOI:10.1007/s00216-015-8687-1 · 3.58 Impact Factor
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    ABSTRACT: In this work, the electrochemical parameters, namely, amount of charge consumed, electron transfer rate constant, cathodic peak current, surface coverage, full width at half maximum of cathodic peak height and tributyrin concentration were interrelated to improve the figure of merits of the TCO/Nano-CeO2/lipase electrode towards the estimation of tributyrin in human serum samples. Principal component and hierarchical cluster analyses were performed with the estimated value of electrochemical parameters illustrated that the amount of charge consumed, cathodic peak current, surface coverage and full width at half maximum of cathodic peak height were significantly related with tributyrin concentration. And finally, a multiple linear regression model capable of reliably predicting tributyrin in human serum samples was developed.
    Journal of Computational and Theoretical Nanoscience 04/2015; 12(6). DOI:10.1166/jctn.2015.3832 · 1.34 Impact Factor
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    ABSTRACT: Linear sweep voltammetry was used as an analytical technique to measure methylglyoxal in blood samples by employing Pt/ZnO sepals/GLO 1 bio-electrode. In order to increase the specificity of glyoxalase towards methylglyoxal and to predict the non-linear relationship between added methylglyoxal concentrations and pairs of electrochemical parameters, non-linear logistic and gaussian cumulative response surface models were fitted to the experimental results using Levenberg-Marquardt algorithm. An excellent correlation (r = 0.99) was observed between the predicted and added methylglyoxal concentrations. The accuracy of the proposed models was validated by calculating relative prediction error (RPE), percentage recovery and root mean square error for cross validation (RMSECV). Only the MG = f(FWHM, Jpc) logistic cumulative response model showed best results in validation (RPE = 2.07 × 10–5, Recovery = 98.726% and RMSECV = –0.004). The calibrated non-linear model was further validated on human blood samples. The attained relative standard deviation and percentage recovery values calculated for spiked methylglyoxal concentrations (3 measurements) were typically below 6.54% and 116.48% respectively.
    Sensor Letters 04/2015; 13(4). DOI:10.1166/sl.2015.3439 · 0.56 Impact Factor
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    ABSTRACT: Theoretical investigation for the estimation of surface coverage based on Michaelis-Menten constant (K M) and detection limit was carried out. The influence of theoretical linear ranges on the surface concentration of adsorbed biomolecules was also investigated. The [S] K M boundary-conditioned surface coverage model results are consistent with the theoretical calculations and give a precise determination of surface coverage.
    Sensor Letters 04/2015; 13(4). DOI:10.1166/sl.2015.3438 · 0.56 Impact Factor
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    ABSTRACT: Until now, various chemometric tools have been used to approximate solutions to address the nonlinear amperometric biosensor modeling challenge. Hence, an analytical method capable of predicting the non-constant slope (dynamic sensitivity) of a non-linear amperometric biosensor model has been developed. The dynamic sensitivity, and any given point in a given amperometric biosensor's operation, is predicted by solving a series of mathematical constants corresponding to the physical entities of the amperometric biosensor itself. In order to validate the proposed models, data of butyrin biosensor were considered. The effectiveness of these models was statistically analyzed and found that the first-order dynamic sensitivity model was better than that of the second order. This dynamic sensitivity slope prediction, in turn, can be used to predict the concentration of an analyte when a non-constant amperometric sensor response is known.
    Journal of Computational and Theoretical Nanoscience 04/2015; 12(6). DOI:10.1166/jctn.2015.3853 · 1.34 Impact Factor
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    ABSTRACT: A hybrid interface was developed using nano iron oxide and carbon nanotubes and this architecture offered an improved performance for the detection of hydrogen peroxide. Nano iron oxide was synthesized by a simple thermal co-precipitation technique and it was dispersed in nafionic solution. To this mixture added the catalase enzyme adsorbed multi-walled carbon nanotubes and this solution was used for the modification of the electrode. The morphology of the prepared nanocomposite was observed using FE-TEM and the electrochemical studies were carried out using cyclic voltammetry and amperometry. The linear range of the prepared amperometric sensor was found to be between 1.2 - 21.6 μM with a quick response time of less than 1 second. The interference, reproducibility and stability studies were carried out with satisfactory results. The limit of detection and limit of quantification was found to be 3.7 nM and 12.2 nM respectively. With the convincing results obtained in terms of the performance of the biosensor, this platform was successfully upgraded for the determination of hydrogen peroxide in the presence of milk samples.
    Sensors and Actuators B Chemical 03/2015; · 3.84 Impact Factor
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    ABSTRACT: Linear sweep voltammetric behaviour of methylglyoxal was investigated using Pt/ZnO flakes/GLO 1 bio-electrode and a new analytical method was developed for the precise and accurate determination of methylglyoxal in grilled chicken sample. This method was based on the electrochemical parameters measured for the increasing concentration of methylglyoxal. The electrochemical parameters calculated from the linear sweep voltammograms served as the dependent variables. The concentrations of methylglyoxal were employed as the independent variables. For each electrochemical parameter, a non-linear calibration equation was framed and its predictive performance was evaluated. The analytical performance of the proposed models was assessed with the aid of relative prediction error, % recovery and root mean square error for cross validation. The best results were obtained with current density versus [methylglyoxal] model (RPE = 0.033, Recovery = 97.379% and RMSECV = 1.429). This calibrated non-linear model was then applied for the determination of methylglyoxal in grilled chicken samples. The recovery of methylglyoxal in spiked grilled chicken was ranging from 95.895% to 108.191%. The predicted methylglyoxal values were very similar to that of the spiked methylglyoxal values.
    Sensor Letters 03/2015; 13(3). DOI:10.1166/sl.2015.3425 · 0.56 Impact Factor
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    ABSTRACT: Estimating lactate concentration in the meat food products has been a serious concern since it induces hepatic immaturity in children below the age of 3. This article is aimed to illustrate the statistical modeling for the estimation of lactate in meat food products and to identify the interrelation between the amount of lactate added to the phosphate buffered saline (0.1 M, 7.4 pH) and other electrochemical parameters such as amount of charge consumed, surface coverage, cathodic peak current, cathodic peak potential, full width at half maximum of cathodic peak height and electron transfer rate constant. The gold working electrode was modified by immobilizing lactate dehydrogenase on ZnO nanorods. The modified gold working electrode was used for the determination of lactate by linear sweep voltammetry. Multivariate data analysis was performed with the values of electrochemical parameters. This analysis showed the significant relation between the amount of charge consumed and full width at half maximum of cathodic peak height with the added lactate concentrations. Based on these relationships, a multiple linear regression model was framed for the estimation of lactate in meat food products.
    Journal of Computational and Theoretical Nanoscience 03/2015; 12(3). DOI:10.1166/jctn.2015.3744 · 1.34 Impact Factor
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    ABSTRACT: Nano delivery systems have significantly evolved over the last decade for the treatment of cancer by enabling site-specific delivery and improved bioavailability. The widely investigated nanoparticle systems are biodegradable polyesters, dendrimers, liposomes, mesoporous silica and gold nanoparticles. These particles when conjugated with different targeting motifs enhance the therapeutic efficiency of the drug molecules and biocompatibility. However, the application of such systems towards the treatment of retinoblastoma (RB), a rapidly spreading childhood eye cancer, still remains in its infancy. Nanoparticle-based systems that have been investigated for RB therapy have displayed improved drug delivery to the most restricted posterior segment of the eyes and have increased intra-vitreal half-life of the chemotherapy agents highlighting its potential in treatment of this form of cancer. This review focuses on the challenges involved in the treatment of RB and highlights the attempts made to develop nano-dimensional systems for the treatment of RB.
    Drug Delivery 02/2015; DOI:10.3109/10717544.2015.1016193 · 2.20 Impact Factor
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    ABSTRACT: Objective: A major limitation in gene delivery applications employing nanocarriers is the inflammatory response elicited when administered in vivo. The mode of complexation of the oligonucleotide with the carrier can alter its interactions with biomolecules, a fact that has not been explored for lipoplexes hitherto. Materials: Liposomes prepared by thin film hydration were used to form lipoplexes of si-RNA and DNA, which exhibited a smaller size and a shift towards negative zeta potential when compared with blank liposomes. Results: The oligonucleotides wrap over the liposome surface and the surface coverage depends on the number of base pairs. The colloidal stability, protein resistance and cell uptake of lipoplexes were found to be dependent on surface charge and PEG. The lipoplexes with si-RNA did not induce cytokine production in BALB/c mice. Conclusion: The results highlight the importance of PEGylation for achieving good protein resistance without compromising cell uptake and therapeutic efficiency.
    Nano brief reports and reviews 01/2015; DOI:10.1142/S1793292015500526 · 1.26 Impact Factor
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    ABSTRACT: Regeneration of functional small diameter blood vessels still remains a challenge, as the synthetic vascular grafts fail to mimic the complex structural architecture and dynamic functions of blood vessels and also lack with the lack of non-thrombogenicity. Although, the existence of nanofibrous extracellular matrix components in the native tissue promotes many physical and molecular signals to the endothelial cells for the regulation of morphogenesis, homeostasis, and cellular functions in vascular tissue, poor understanding of the structural architecture on the functional activation of appropriate genes limits the development of successful vascular graft design. Hence, the present review outlines the functional contributions of various nanofibrous extracellular matrix components in native blood vessels. Further, the review focuses on the role of nanofiber topography of biomaterial scaffolds in endothelial cell fate processes such as adhesion, proliferation, migration, and infiltration with the expression of vasculature specific genes; thereby allowing the reader to envisage the communication between the nano-architecture of scaffolds and endothelial cells in engineering small diameter vascular grafts.
    Biotechnology Journal 01/2015; 10(1). DOI:10.1002/biot.201400415 · 3.71 Impact Factor
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    ABSTRACT: Three-dimensional liver scaffolds are temporary framework that mimics native ECM architecture and positively influence hepatocyte lodging, proliferation with retention of metabolic activities. The aim of the current study is to develop galactose containing physical cross-linked polyvinyl alcohol/gelatin (P/G 8:2 and 9:1) hydrogel scaffolds via freeze/thaw technique. The 8:2 and 9:1 P/G hydrogels exhibited comparable pore size and porosity (P > 0.05). The tensile strength of the fabricated 8:2 and 9:1 P/G hydrogel scaffolds were found to be in accordance with native human liver. Pore interconnectivity of both the P/G hydrogel scaffolds was confirmed by scanning electron micrographs and liquid displacement method. Further galactose containing hydrogel promoted cell-cell and cell-hydrogel interaction, aiding cellular aggregation leading to spheroids formation compared to void P/G hydrogel by 7 days. Hence, galactose containing P/G hydrogel could be more promising substrate as it showed significantly higher cell proliferation and albumin secretion for 21 days when compared to non-galactose P/G hydrogels (P < 0.05).
    Journal of Materials Science Materials in Medicine 01/2015; 26(1):5345. DOI:10.1007/s10856-014-5345-7 · 2.38 Impact Factor
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    ABSTRACT: In the view of difficulties in finding the recovery and inhibition of an immobilized enzyme from the degree of inhibition, an equation based upon the degree of inhibition has been developed by considering incubation time at different time intervals. In this work, data of an enzymatic kinetic reaction at different incubation time intervals were used to exemplify practicability of the proposed equation in the field of enzyme-inhibition based electrochemical biosensor. For validation purpose, the results obtained from the extended bio-analytical approach were compared to the degree of inhibition and the results were found to be satisfactory. Using this extended bio-analytical technique, the degree of toxicity of environmental toxicants can be determined.
    Journal of Computational and Theoretical Nanoscience 01/2015; 12(1):88-93. DOI:10.1166/jctn.2015.3702 · 1.34 Impact Factor
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    ABSTRACT: Highly active antiretroviral therapy (HAART) is the currently employed therapeutic intervention against AIDS where a drug combination is used to reduce the viral load. The present work envisages the development of a stealth Anti-CD4 conjugated immunoliposomes containing two anti-retroviral drugs (nevirapine and saquinavir) that can selectively home into HIV infected cells through the CD4 receptor. The nanocarrier was characterized using transmission electron microscopy, FTIR, differential scanning calorimetry, particle size and zeta potential. The cell uptake was also evaluated qualitatively using confocal microscopy and quantitatively by flow cytometry. The drug to lipid composition was optimized for maximum encapsulation of the two drugs. Both drugs were found to localize in different regions of the liposome. The release of the reverse transcriptase inhibitor was dominant during the early phases of the release while in the later phases, the protease inhibitor is the major constituent released. The drugs delivered via Anti-CD4 conjugated immunoliposomesss inhibited viral proliferation at a significantly lower concentration as compared to free drugs. In vitro studies of nevirapine to saquinavir combination at a ratio of 6.2:5 and a concentration as low as 5 ng/mL efficiently blocked viral proliferation suggesting that co-delivery of anti-retroviral drugs holds a greater promise for efficient management of HIV-1 infection. Copyright © 2014. Published by Elsevier B.V.
    European Journal of Pharmaceutics and Biopharmaceutics 12/2014; 89. DOI:10.1016/j.ejpb.2014.11.021 · 4.25 Impact Factor
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    ABSTRACT: The tunable textural properties of self-oriented mesoporous silica were investigated for their suitability as enzyme immobilization matrices to support transesterification of rice bran oil. Different morphologies of mesoporous silica (rod-like, rice-like, and spherical) were synthesized and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption–desorption isotherms. The surface area, pore size, and ordered arrangement of the pores were found to influence the immobilization and activity of the enzyme in the mesopores. The immobilization in rod-like silica was highest with an immobilization efficiency of 63 % and exhibited minimal activity loss after immobilization. Functionalization of the mesoporous surface with ethyl groups further enhanced the enzyme immobilization. The free enzyme lost most of its activity at 50 °C while the immobilized enzyme showed activity even up to 60 °C. Transesterified product yield of nearly 82 % was obtained for 24 h of reaction with enzyme immobilized on ethyl-functionalized SBA-15 at an oil:methanol ratio of 1:3. Fourier transform infrared spectroscopy (FT–IR) and Gas chromatography–mass spectrometry (GC-MS) were used to characterize the transesterified product obtained. The reusability of the immobilized enzyme was studied for 3 cycles.
    Applied Biochemistry and Biotechnology 12/2014; 175(5). DOI:10.1007/s12010-014-1432-y · 1.74 Impact Factor
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    ABSTRACT: The membrane interactions and localization of flavonoids play a vital role in altering membrane-mediated cell signaling cascades as well as influence the pharmacological activities such as anti-tumour, anti-microbial and anti-oxidant properties of flavonoids. Various techniques have been used to investigate the membrane interaction of flavonoids. These include partition coefficient, fluorescence anisotropy, differential scanning calorimetry, NMR spectroscopy, electrophysiological methods and molecular dynamics simulations. Each technique will provide specific information about either alteration of membrane fluidity or localization of flavonoids within the lipid bilayer. Apart from the diverse techniques employed, the concentrations of flavonoids and lipid membrane composition employed in various studies reported in literature also are different and together these variables contribute to diverse findings that sometimes contradict each other. This review highlights different techniques employed to investigate the membrane interaction of flavonoids with special emphasis on erythrocyte model membrane systems and their significance in understanding the nature and extent of flavonoid-membrane interactions. We also attempt to correlate the membrane localization and alteration in membrane fluidity with the biological activities of flavonoids such as anti-oxidant, anti-cancer and anti-microbial properties. Copyright © 2014. Published by Elsevier Ltd.
    Progress in Lipid Research 12/2014; 58. DOI:10.1016/j.plipres.2014.11.002 · 12.96 Impact Factor

Publication Stats

639 Citations
371.24 Total Impact Points

Institutions

  • 2009–2015
    • SASTRA University
      • • School of Chemical & Biotechnology
      • • Centre for Nanotechnology & Advanced Biomaterials [CeNTAB]
      Tanjor, Tamil Nadu, India
  • 2011
    • Hebrew University of Jerusalem
      Yerushalayim, Jerusalem, Israel