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B D Malhotra - One of the best experts on this subject based on the ideXlab platform.
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nanostructured anatase titanium dioxide based platform for application to microfluidics Cholesterol biosensor
Applied Physics Letters, 2012Co-Authors: Md Azahar Ali, Saurabh Srivastava, Pratima R Solanki, Ved Varun Agrawal, Renu John, B D MalhotraAbstract:We report results of studies relating to the fabrication of a microfluidics Cholesterol sensor based on nanocrystalline anatase-titanium dioxide (ant-TiO2) film deposited onto indium tin oxide (ITO) glass. The results of response studies (optimized under the flow rate of 30 μl/min) conducted on Cholesterol Oxidase (ChOx) immobilized onto crystalline ant-TiO2 nanoparticles (∼27 nm)/ITO microfluidics electrode reveal linearity as 1.3 to 10.3 mM and improved sensitivity of 94.65 μA/mM/cm2. The observed low value of Km (0.14 mM) indicates high affinity of ChOx to Cholesterol. No significant changes in current response of this microfluidics sensor are measured in the presence of different interferents.
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functionalized gold nanoparticles octadecylamine hybrid langmuir blodgett film for enzyme sensor
Electroanalysis, 2009Co-Authors: Pratibha Pandey, Vinay Gupta, Zimple Matharu, Madhurima Pandey, B D MalhotraAbstract:Mediator free enzyme sensor has been fabricated by covalently immobilizing Cholesterol Oxidase (ChOx) onto 11-mercaptoundecanoic acid functionalized gold nanoparticles (MUDA-AuNPs) – octadecylamine (ODA) hybrid Langmuir–Blodgett film. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies reveal that MUDA-AuNP/ODA LB film has good affinity for ChOx and provides favorable microenvironment for direct electron transfer between enzyme and electrode. Interference free estimation of Cholesterol has been realized at 0.3 V with linear range from 25 to 500 mg/dL, detection limit of 23.38 mg/dL, sensitivity of 1.085 μA mM−1 and response time of 20 s at pH 7.0.
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sol gel derived nanoporous cerium oxide film for application to Cholesterol biosensor
Electrochemistry Communications, 2008Co-Authors: Anees A Ansari, Pratima R Solanki, Ajeet Kaushik, B D MalhotraAbstract:Abstract Cholesterol Oxidase (ChOx) has been immobilized onto sol–gel derived nano-structured cerium oxide (NS-CeO 2 ) film deposited on indium-tin-oxide (ITO) coated glass substrate. Phase identification of sol–gel NS-CeO 2 film carried out using X-ray diffraction (XRD) yields reflection peak at 29.4° corresponding to (1 1 1) plane with oriented crystallite (34 nm) along c -axis normal to the substrate. Electrochemical studies reveal that NS-CeO 2 provides electroactive surface for the loading of ChOx and enhances electron transfer rate in the ChOx/NS-CeO 2 /ITO bioelectrode. The low value of Michaelis–Menten constant ( K m ) obtained as 2.08 mM indicates enhanced ChOx affinity to Cholesterol. The observed results show application of sol–gel derived NS-CeO 2 for biosensing without any functionalization.
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Cholesterol biosensor based on electrophoretically deposited conducting polymer film derived from nano structured polyaniline colloidal suspension
Analytica Chimica Acta, 2007Co-Authors: Chetna Dhand, Sunil K Arya, Surinder P Singh, Monika Datta, B D MalhotraAbstract:Abstract Cholesterol Oxidase (ChOx) has been covalently immobilized onto electrophoretically deposited conducting polymer film (on indium-tin-oxide (ITO) glass plate) derived from nano-structured polyaniline (PANI) colloidal suspension using N-ethyl-N′-(3-dimethylaminopropyl) corbodiimide (EDC) and N-hydroxysuccinimide (NHS) chemistry. These PANI/ITO and ChOx/PANI/ITO electrodes have been characterized using ultraviolet-visible (UV-vis), Fourier transform-infrared (FT-IR), scanning electron microscopy (SEM), and impedance spectroscopy techniques, respectively. These ChOx/PANI/ITO bio-electrodes exhibit linearity from 25 to 400 mg dL−1 of Cholesterol, detection limit as 25 mg dL−1 and sensitivity as 7.76 × 10−5 Abs (mg/dL)−1. The value of the apparent Michaelis–Menten constant ( K m app ) calculated from amperometric response studies has been found to be 0.62 mM for ChOx/PANI/ITO bio-electrode.
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Cholesterol biosensor based on rf sputtered zinc oxide nanoporous thin film
Applied Physics Letters, 2007Co-Authors: S P Singh, Sunil K Arya, Pratibha Pandey, B D Malhotra, Shibu Saha, K Sreenivas, Vinay GuptaAbstract:Cholesterol Oxidase (ChOx) has been immobilized onto zinc oxide (ZnO) nanoporous thin films grown on gold surface. A preferred c-axis oriented ZnO thin film with porous surface morphology has been fabricated by rf sputtering under high pressure. Optical studies and cyclic voltammetric measurements show that the ChOx∕ZnO∕Au bioelectrode is sensitive to the detection of Cholesterol in 25–400mg∕dl range. A relatively low value of enzyme’s kinetic parameter (Michaelis-Menten constant) ∼2.1mM indicates enhanced enzyme affinity of ChOx to Cholesterol. The observed results show promising application of nanoporous ZnO thin film for biosensing application without any functionalization.
Suman Singh - One of the best experts on this subject based on the ideXlab platform.
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immobilization of Cholesterol esterase and Cholesterol Oxidase onto sol gel films for application to Cholesterol biosensor
Analytica Chimica Acta, 2007Co-Authors: Suman Singh, Rahul Singhal, B D MalhotraAbstract:Abstract Cholesterol Oxidase (ChOx) and Cholesterol esterase (ChEt) have been covalently immobilized onto tetraethylorthosilicate (TEOS) sol–gel films. The tetraethylorthosilicate sol–gel/ChEt/ChOx enzyme films thus prepared have been characterized using scanning electron microscopic (SEM), UV–vis spectroscopic, Fourier-transform-infrared (FTIR) spectroscopic and amperometric techniques, respectively. The results of photometric measurements carried out on tetraethylorthosilicate sol–gel/ChEt/ChOx reveal thermal stability up to 55 °C, response time as 180 s, linearity up to 780 mg dL−1 (12 mM), shelf life of 1 month, detection limit of 12 mg dL−1 and sensitivity as 5.4 × 10−5 Abs. mg−1 dL−1.
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Cholesterol biosensor based on Cholesterol esterase Cholesterol Oxidase and perOxidase immobilized onto conducting polyaniline films
Sensors and Actuators B-chemical, 2006Co-Authors: Suman Singh, M K Pandey, Pratima Rathee Solanki, Bansi Dhar MalhotraAbstract:Cholesterol Oxidase, Cholesterol esterase and perOxidase have been co-immobilized onto electrochemically prepared polyaniline films. These polyaniline–enzyme films characterized using spectroscopic techniques, have been used to fabricate a Cholesterol biosensor. This polyaniline-based Cholesterol biosensor has a response time of about 240 s, an apparent Km value as 75 mg dl−1 and can be used to estimate Cholesterol concentration up to 500 mg dl−1. These polyaniline/Cholesterol Oxidase/Cholesterol esterase films have a detection limit of 25 mg dl−1 with sensitivity of 0.042 μA mg dl−1. The enzyme films were found to be thermally stable up to 48 °C and have a shelf-life of about 6 weeks when stored at 4 °C. The values of the activation energy before and after the critical temperature were found to be 191 and 95.5 kJ mol−1, respectively.
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Covalent immobilization of Cholesterol esterase and Cholesterol Oxidase on polyaniline films for application to Cholesterol biosensor.
Analytica chimica acta, 2005Co-Authors: Suman Singh, M K Pandey, Pratima Rathee Solanki, Bansi Dhar MalhotraAbstract:Cholesterol esterase (ChEt) and Cholesterol Oxidase (ChOx) have been covalently immobilized on electrochemically prepared polyaniline (PANI) films. These PANI/ChEt/ChOx enzyme films have been characterized using UV-visible, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Electrochemical behavior of these films has been studied using cyclic voltammetry (CV) and amperometric techniques, respectively. The PANI/ChEt/ChOx enzyme films show broad oxidation peak from 0.2 to 0.5 V. These PANI/ChEt/ChOx biosensing electrodes have a response time of about 40s, linearity from 50 to 500 mg/dl of Cholesterol oleate concentration. These PANI/ChEt/ChOx films are thermally stable up to 46 degrees C. This polyaniline based Cholesterol biosensor has optimum pH in the range of 6.5-7.5, sensitivity as 7.5x10(-4) nA/mg dl and a lifetime of about 6 weeks.
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preparation and characterization of an enzyme electrode based on Cholesterol esterase and Cholesterol Oxidase immobilized onto conducting polypyrrole films
Journal of Applied Polymer Science, 2004Co-Authors: Suman Singh, Asha Chaubey, B D MalhotraAbstract:Cholesterol esterase (ChEt) and Cholesterol Oxidase (ChOx) enzymes were entrapped within polypyrrole (PPy) films on a platinum disc electrode during electrochemical polymerization. The characteristics of the PPy/ChEt/ChOx enzyme electrode thus prepared were investigated as a function of the time, pH, temperature, and concentration of cholesteryl palmitate by a spectrophotometric method. PPy/ChEt/ChOx electrodes can be used for the estimation of cholesteryl palmitate concentrations from 1 to 8 mM, can be used least 10 times, and have a shelf life of about 1 month at 4–10°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3769–3773, 2004
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amperometric Cholesterol biosensor based on immobilized Cholesterol esterase and Cholesterol Oxidase on conducting polypyrrole films
Analytica Chimica Acta, 2004Co-Authors: Suman Singh, Asha Chaubey, B D MalhotraAbstract:Abstract Fabrication of an amperometric Cholesterol biosensor by co-immobilization of Cholesterol esterase (ChEt) and Cholesterol Oxidase (ChOx) onto conducting polypyrrole (PPY) films using electrochemical entrapment technique is described. Electrochemical polymerization was carried out using a two-electrode cell configuration at 0.8 V. Characterization of resulting amperometric biosensor for the estimation of Cholesterol has been experimentally determined in terms of linear response range, optimum pH, applied potential, temperature, and shelf-life. These PPY/ChEt/ChOx electrodes can be used for Cholesterol ester estimation from 1 to 8 mM and have shelf-life of about 4 weeks at 4 °C during which about 15 estimations of Cholesterol ester could be made. The sensitivity of PPY/ChEt/ChOx electrode has been found to be 0.15 μA/mM and the apparent Km value for this electrode is 9.8 mM. Conductivity of the polymer films found to be about 3×10−3 S/cm.
Samuel B O Adeloju - One of the best experts on this subject based on the ideXlab platform.
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a single step electrochemical integration of gold nanoparticles Cholesterol Oxidase Cholesterol esterase and mediator with polypyrrole films for fabrication of free and total Cholesterol nanobiosensors
Talanta, 2018Co-Authors: Mohd Zulkhairi Rahim, Gwen Govenderhondros, Samuel B O AdelojuAbstract:Abstract The development of free and total Cholesterol nanobiosensors based on a single step electrochemical integration of gold nanoparticles (AuNPs), Cholesterol Oxidase (COx), Cholesterol esterase (CE) and a mediator with polypyrrole (PPy) films is described. The incorporation of the various components in the PPy films was confirmed by chronopotentiometry, cyclic voltammetry (CV), scanning electron microscopy, energy dispersive X-ray analysis (SEM-EDX), and Fourier transformed infrared (FTIR) spectroscopy. The free Cholesterol, PPy-NO3--Fe(CN)64--AuNPs-COx, nanobiosensor achieved a minimum detectable concentration of 5 μM, a linear concentration range of 5–25 μM and a sensitivity of 1.6 µA cm−2 µM−1 in 0.05 M phosphate buffer (pH 7.00). For the total Cholesterol, PPy-NO3--Fe(CN)64--AuNPs-COx-CE, nanobiosensor which also involved the co-incorporation of Cholesterol esterase (CE) with the other components, the achieved performances include a minimum detectable total Cholesterol concentration of 25 μM, a broader linear concentration range of 25–170 μM and a lower sensitivity of 0.1 µA µM−1 cm−2. Owing to its high selectivity, the presence of common interferants did not affect the total Cholesterol measurement with the PPy-NO3--Fe(CN)64--AuNPs-COx-CE nanobiosensor. Both nanobiosensors were successfully used for direct and indirect determination of total Cholesterol in human blood serum samples.
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a single step electrochemical integration of gold nanoparticles Cholesterol Oxidase Cholesterol esterase and mediator with polypyrrole films for fabrication of free and total Cholesterol nanobiosensors
Talanta, 2018Co-Authors: Mohd Zulkhairi Rahim, Gwen Govenderhondros, Samuel B O AdelojuAbstract:Abstract The development of free and total Cholesterol nanobiosensors based on a single step electrochemical integration of gold nanoparticles (AuNPs), Cholesterol Oxidase (COx), Cholesterol esterase (CE) and a mediator with polypyrrole (PPy) films is described. The incorporation of the various components in the PPy films was confirmed by chronopotentiometry, cyclic voltammetry (CV), scanning electron microscopy, energy dispersive X-ray analysis (SEM-EDX), and Fourier transformed infrared (FTIR) spectroscopy. The free Cholesterol, PPy-NO3--Fe(CN)64--AuNPs-COx, nanobiosensor achieved a minimum detectable concentration of 5 μM, a linear concentration range of 5–25 μM and a sensitivity of 1.6 µA cm−2 µM−1 in 0.05 M phosphate buffer (pH 7.00). For the total Cholesterol, PPy-NO3--Fe(CN)64--AuNPs-COx-CE, nanobiosensor which also involved the co-incorporation of Cholesterol esterase (CE) with the other components, the achieved performances include a minimum detectable total Cholesterol concentration of 25 μM, a broader linear concentration range of 25–170 μM and a lower sensitivity of 0.1 µA µM−1 cm−2. Owing to its high selectivity, the presence of common interferants did not affect the total Cholesterol measurement with the PPy-NO3--Fe(CN)64--AuNPs-COx-CE nanobiosensor. Both nanobiosensors were successfully used for direct and indirect determination of total Cholesterol in human blood serum samples.
Shangtian Yang - One of the best experts on this subject based on the ideXlab platform.
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identification of steroid c27 monooxygenase isoenzymes involved in sterol catabolism and stepwise pathway engineering of mycobacterium neoaurum for improved androst 1 4 diene 3 17 dione production
Journal of Industrial Microbiology & Biotechnology, 2019Co-Authors: Minglong Shao, Xian Zhang, Zhiming Rao, Taowei Yang, Shangtian YangAbstract:Cholesterol Oxidase, steroid C27 monooxygenase and 3-ketosteroid-Δ1-dehydrogenase are key enzymes involved in microbial catabolism of sterols. Here, three isoenzymes of steroid C27 monooxygenase were firstly characterized from Mycobacterium neoaurum as the key enzyme in sterol C27-hydroxylation. Among these three isoenzymes, steroid C27 monooxygenase 2 exhibits the strongest function in sterol catabolism. To improve androst-1,4-diene-3,17-dione production, Cholesterol Oxidase, steroid C27 monooxygenase 2 and 3-ketosteroid-Δ1-dehydrogenase were coexpressed to strengthen the metabolic flux to androst-1,4-diene-3,17-dione, and 3-ketosteroid 9α-hydroxylase, which catalyzes the androst-1,4-diene-3,17-dione catabolism, was disrupted to block the androst-1,4-diene-3,17-dione degradation pathway in M. neoaurum JC-12. Finally, the recombinant strain JC-12S2-choM-ksdd/ΔkshA produced 20.1 g/L androst-1,4-diene-3,17-dione, which is the highest reported production with sterols as substrate. Therefore, this work is hopes to pave the way for efficient androst-1,4-diene-3,17-dione production through metabolic engineering.
Bansi Dhar Malhotra - One of the best experts on this subject based on the ideXlab platform.
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Cholesterol biosensor based on Cholesterol esterase Cholesterol Oxidase and perOxidase immobilized onto conducting polyaniline films
Sensors and Actuators B-chemical, 2006Co-Authors: Suman Singh, M K Pandey, Pratima Rathee Solanki, Bansi Dhar MalhotraAbstract:Cholesterol Oxidase, Cholesterol esterase and perOxidase have been co-immobilized onto electrochemically prepared polyaniline films. These polyaniline–enzyme films characterized using spectroscopic techniques, have been used to fabricate a Cholesterol biosensor. This polyaniline-based Cholesterol biosensor has a response time of about 240 s, an apparent Km value as 75 mg dl−1 and can be used to estimate Cholesterol concentration up to 500 mg dl−1. These polyaniline/Cholesterol Oxidase/Cholesterol esterase films have a detection limit of 25 mg dl−1 with sensitivity of 0.042 μA mg dl−1. The enzyme films were found to be thermally stable up to 48 °C and have a shelf-life of about 6 weeks when stored at 4 °C. The values of the activation energy before and after the critical temperature were found to be 191 and 95.5 kJ mol−1, respectively.
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Covalent immobilization of Cholesterol esterase and Cholesterol Oxidase on polyaniline films for application to Cholesterol biosensor.
Analytica chimica acta, 2005Co-Authors: Suman Singh, M K Pandey, Pratima Rathee Solanki, Bansi Dhar MalhotraAbstract:Cholesterol esterase (ChEt) and Cholesterol Oxidase (ChOx) have been covalently immobilized on electrochemically prepared polyaniline (PANI) films. These PANI/ChEt/ChOx enzyme films have been characterized using UV-visible, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Electrochemical behavior of these films has been studied using cyclic voltammetry (CV) and amperometric techniques, respectively. The PANI/ChEt/ChOx enzyme films show broad oxidation peak from 0.2 to 0.5 V. These PANI/ChEt/ChOx biosensing electrodes have a response time of about 40s, linearity from 50 to 500 mg/dl of Cholesterol oleate concentration. These PANI/ChEt/ChOx films are thermally stable up to 46 degrees C. This polyaniline based Cholesterol biosensor has optimum pH in the range of 6.5-7.5, sensitivity as 7.5x10(-4) nA/mg dl and a lifetime of about 6 weeks.