Biosensors cholesterol

Trettnak W., Wolfbeis O.S., Fiber optic cholesterol biosensor with an oxygen optrode as the transducer Anal. Biochem. 1990 184 124. 

J.C. Vidal, J. Espuelas, E. Garda-Ruiz, and J.R. Castillo, Amperometric cholesterol biosensors based on the electropolymerization of pyrrole and the electrocatalytic effect of Prussian-Blue layers helped with self-assembled monolayers. Talanta 64, 655 (2004). 

J.P. Li, T.Z. Peng, and Y.Q. Peng, A cholesterol biosensor based on entrapment of cholesterol oxidase in a silicic sol-gel matrix at a Prussian blue modified electrode. Electroanalysis 15, 1031—1037 (2003). 

X.C. Tan, MJ. Li, RX. Cai, LJ. Luo, and X.Y. Zou, An amperometric cholesterol biosensor based on multiwalled carbon nanotubes and organically modified sol-gel/chitosan hybrid composite film. Anal. Biochem. 337, 111-120 (2005). 

An SPCE modified with CoPC was employed as an H202 transducer in a cholesterol biosensor fabricated by the drop-coating of ChOx, followed by a cellulose acetate membrane [50]. The resulting cholesterol biosensors were operated in stirred solutions using an applied potential of +400 mV vs. screen-printed Ag/AgCl, and displayed a linear range of 0.06-5 mM. 

M.A.T. Gilmartin and J.P. Hart, Fabrication and characterization of a screen-printed, disposable, amperometric cholesterol biosensor, Analyst, 119 (1994) 2331-2336. 

Zhao C, Wan L, Jiang L, Wang Q, Jiao K (2008) Highly sensitive and selective cholesterol biosensor based on direct electron transfer of haemoglobin. Anal Biochem 383 25-30... 

Figure 2. The mechanism for preparation of Nano ZnO-CHIT electrode and immobilization of ChOx onto NanoZnO-CHIT Nanocomposite, Reprinted from Analytica Chimica Acta, 616, R. Khan, A. Kaushik, P. R. Solanki, A.A. Ansari, M.K. Pandy, B.D. Malhotra, Zinc oxide nanoparticles -chitosan composite film for cholesterol biosensor, 209,Copyright( 2008) with permission fom Elsevier.

The development and application of biosensors has been discussed in several reviews [125, 126]. For instance, fabrication of cholesterol biosensors relies on the immobilization of cholesterol oxidase and cholesterol esterase onto CNTs, while horseradish peroxidase and flavocytochrome P450scc are also used for the same reason [125, 126]. Beyond the biosensing field, carbon nanotubes are also used as carriers for peptide, nucleic acid and drug delivery, due to their intrinsic property to cross cell membranes [102, 124]. The fact that the functionalized CNTs (f-CNTs) are not immunogenic and low-toxic opens the pathway for more research in the field of CNT-abetted drug delivery [102]. 

C. Dhand, S. P. Singh, S. K. Arya, M. Datta, and B. D. Malhotra, Cholesterol biosensor based on electrophoretically deposited conducting polymer film derived from nano-structured polyaniline colloidal suspension. Anal. Chim. Acta 602, 244-251 (2007). 

P.R. Solanki, S. Singh, N. Prabhiar, M.K. Pandey, and B.D. Malhotra, Apphcation of conducting poly(aniline-co-pyrrole) film to cholesterol biosensor, J. Appl. Polym. ScL, 105(6), 3211-3219 (2007). 

A simple and inexpensive cholesterol biosensor was fabricated by immobilizing cholesterol oxidase (ChOx) and horseradish peroxidase (HRP) onto a poly (thionine) modified glassy carbon electrode (GCE/PTH) (Fig. 41) [122]. Hydroqui-none (HQ) was used as a mediator to promote the electron transfer between the enzyme and the electrode. It results in excellent electrocatalytic activity of immobilized HRP for H2O2 reduction, which was produced from cholesterol by the enzymatic reaction with ChOx. The linear range for cholesterol spanned from 25 to 125 iM, with a detection limit and a sensitivity of 6.3 pM and 0.18 pA/cm /p M, respectively. The highly reproducible and sensitive GCE/PTH/ChOx/HRP sensor exhibited an interference-free signal for cholesterol detection with excellent recoveries for real sample analysis. 

Rahman MM, X-b L, Kim J, Lim BO, Ahammad A, Lee J-J (2014) A cholesterol biosensor based on a bi-enzyme immobilized on conducting poly (thionine) film. Sensor Actuat B Chem 202 536... 

Dhand, C., Arya, S. K., Datta, M., and Malhotra, B. D. (2008). Polyaniline-carbon nanotube composite film for cholesterol biosensor. Anal. Biochem., 383, pp. 194-199. 

Keywords-. Conducting polymers, nanocomposites, biosensors, immunosen-sors, bioaffinity sensors, DNA biosensors, cholesterol biosensors, glucose biosensors, electrochemical biosensor, sensitivity, response time, recovery time selectivity, reversibility, polyanihne, polypyrrole, graphene, carbon nanotubes, nanoparticles... 

Deepshikha etal. have fabricated a novel nanobiocomposite bienzymatic amperometric cholesterol biosensor, coupled with cholesterol oxidase (ChOx) and horseradish peroxidase (HRP), based on the gold nanoparticle-decorated graphene-nanostructured PANI nanocomposite (NSPANI-AuNP-GR) film which was electrochemically deposited onto indium tin oxide (ITO) electrode from the nanocomposite (NSPANI-AuNP-GR) dispersion, as synthesized by in situ polymerization technique [166]. The... 

Trettnak and co-workers prepared a cholesterol biosensor by electropolymerising pyrrole in solutions of 0.1 M phosphate buffer containing NaC104 (10 mM) and 15 to 55 lU/ ml of ChOx at 0.8 V vs SCE (standard calomel electrode) [190]. The sensor shows high reproducibility in the range 0 to 250 pM with the detection limit of about 5 pM of cholesterol. The amperometric cholesterol biosensor based on PPy/ferrocene carboxylic acid electrodes is shown in Figure 10.15. Kumar and co-workers have used... 

Vidal J.C., E. Garcia, and J.R. Castillo. 1999. In situ preparation of a cholesterol biosensor Entrapment of cholesterol oxidase in an overoxidized polypyrrole film electrodeposited in a flow system Determination of total cholesterol in serum. Anal Chim Acta 385 213. 

Singh, S., A. Chaubey, and B.D. Malhotra. 2004. Amperometric cholesterol biosensor based on immobilized cholesterol esterase and cholesterol oxidase on conducting polypyrrole films. Anal Chim Acta 502 (2) 229. 

A new cholesterol FIA biosensor based on a luminol/H202 ECL reaction induced by a glassy carbon electrode polarized at +425 mV versus a Pt pseudo j reference was introduced. The cholesterol biosensor sensing layer used in this method is based on cholesterol oxidase (COD) immobihzed on either UltraBind membrane or Immunodyne membrane [117]. Exploration to other literature shows that heroin was determined employing Zeolite Y sieves by immobilizing... 

Carrara, S., Shumyantseva, V.V., Archakov, A.I., and Samori, B. (2008) Screen-printed electrodes based on carbon nanotubes and cytochrome P450SCC for highly sensitive cholesterol biosensors. Biosens. Bioelectron., 24, 148-150. 

Singh, S. Solanki, P. R. Pandey, M. K. Malhotra, B. D. Cholesterol biosensor based on cholesterol esterase, cholesterol oxidase and peroxidase immobilized onto conducting polyaniline films. Sens. Actuators B Chem. 2006,1, 534—541. 

The process of conversion involved two enzymes cholesterol esterase (ChE) and cholesterol oxidase (ChOx). The former enzyme converts the majority of total cholesterol from esterified cholesterol into free form. The latter will then convert free cholesterol into cholest-4-en-3-one, an important steroid form found in intracellular communicaticHis. The by-product at the end of the reaction (6) is the generated H2O2 that can be electrochemically oxidized or reduced on the surface of cholesterol biosensors. 

Alternatively, self-assembly monolayer approach has also been incorporated to link the protein amine group with the gold surface of electrode. Many thiol-compound-based cholesterol biosensors [51-54] constantly gained... 

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