{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T05:23:23Z","timestamp":1777440203119,"version":"3.51.4"},"reference-count":22,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2009,10,29]],"date-time":"2009-10-29T00:00:00Z","timestamp":1256774400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this report, a new cholesterol sensor is developed based on a vertically aligned CNT electrode with two-step electrochemical polymerized enzyme immobilization. Vertically aligned CNTs are selectively grown on a 1 mm2 window of gold coated SiO2\/Si substrate by thermal chemical vapor deposition (CVD) with gravity effect and water-assisted etching. CNTs are then simultaneously functionalized and enzyme immobilized by electrochemical polymerization of polyaniline and cholesterol enzymes. Subsequently, ineffective enzymes are removed and new enzymes are electrochemically recharged. Scanning electron microscopic characterization indicates polymer-enzyme nanoparticle coating on CNT surface. Cyclic voltammogram (CV) measurements in cholesterol solution show the oxidation and reduction peaks centered around 450 and \u2212220 mV, respectively. An approximately linear relationship between the cholesterol concentration and the response current could be observed in the concentration range of 50\u2013300 mg\/dl with a sensitivity of approximately 0.22 \u03bcA\/mg\u00b7dl\u22121, which is considerably higher compared to previously reported CNT bioprobe. In addition, good specificity toward glucose, uric acid acetaminophen and ascorbic acid have been obtained. Moreover, sensors have satisfactory stability, repeatability and life time. Therefore, the electropolymerized CNT bioprobe is promising for cholesterol detection in normal cholesterol concentration in human blood.<\/jats:p>","DOI":"10.3390\/s91108658","type":"journal-article","created":{"date-parts":[[2009,10,29]],"date-time":"2009-10-29T10:50:22Z","timestamp":1256813422000},"page":"8658-8668","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":55,"title":["High Sensitivity Electrochemical Cholesterol Sensor Utilizing a Vertically Aligned Carbon Nanotube Electrode with Electropolymerized Enzyme Immobilization"],"prefix":"10.3390","volume":"9","author":[{"given":"Anurat","family":"Wisitsoraat","sequence":"first","affiliation":[{"name":"Nanoelectronics and MEMS Laboratory, National Electronics and Computer Technology Center, 112 Thailand Science Park, Pahol Yothin Rd., Klong Luang, Pathumthani 12120, Thailand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chanpen","family":"Karuwan","sequence":"additional","affiliation":[{"name":"Nanoelectronics and MEMS Laboratory, National Electronics and Computer Technology Center, 112 Thailand Science Park, Pahol Yothin Rd., Klong Luang, Pathumthani 12120, Thailand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Krongkamol","family":"Wong-ek","sequence":"additional","affiliation":[{"name":"Nanoelectronics and MEMS Laboratory, National Electronics and Computer Technology Center, 112 Thailand Science Park, Pahol Yothin Rd., Klong Luang, Pathumthani 12120, Thailand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ditsayut","family":"Phokharatkul","sequence":"additional","affiliation":[{"name":"Nanoelectronics and MEMS Laboratory, National Electronics and Computer Technology Center, 112 Thailand Science Park, Pahol Yothin Rd., Klong Luang, Pathumthani 12120, Thailand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Pornpimol","family":"Sritongkham","sequence":"additional","affiliation":[{"name":"Nanoelectronics and MEMS Laboratory, National Electronics and Computer Technology Center, 112 Thailand Science Park, Pahol Yothin Rd., Klong Luang, Pathumthani 12120, Thailand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Adisorn","family":"Tuantranont","sequence":"additional","affiliation":[{"name":"Nanoelectronics and MEMS Laboratory, National Electronics and Computer Technology Center, 112 Thailand Science Park, Pahol Yothin Rd., Klong Luang, Pathumthani 12120, Thailand"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2009,10,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"470","DOI":"10.1093\/clinchem\/20.4.470","article-title":"Enzymatic determination of total serum cholesterol","volume":"20","author":"Allain","year":"1974","journal-title":"Clin. Chem."},{"key":"ref_2","unstructured":"McCreery, R.L. (1991). Electroanalytical Chemistry, Marcel Dekker. [1st ed.]."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1615","DOI":"10.1016\/0039-9140(96)01907-8","article-title":"Polyphenol oxidase-catechol an electroenzymatic model system for characterizing the performance of matrices for biosensors","volume":"43","author":"Bescombes","year":"1996","journal-title":"Talanta"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"568","DOI":"10.1016\/j.bios.2007.06.019","article-title":"Peptide nanowires for coordination and signal transduction of peroxidase biosensors to carbon nanotube electrode arrays","volume":"23","author":"Yeh","year":"2007","journal-title":"Biosens. Bioelectron."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"7171","DOI":"10.1021\/jp014604g","article-title":"Internal surface area evaluation of carbon nanotube with GCMC simulation-assisted N2 adsorption","volume":"106","author":"Ohba","year":"2002","journal-title":"J. Phys. Chem. B"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2140","DOI":"10.1016\/j.bios.2004.09.005","article-title":"Study of carbon nanotube modified biosensor for monitoring total cholesterol in blood","volume":"20","author":"Li","year":"2005","journal-title":"Biosens. Bioelectron."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"559","DOI":"10.1088\/0957-4484\/13\/5\/303","article-title":"Direct electron transfer of glucose oxidase on carbon nanotubes","volume":"13","author":"Lei","year":"2002","journal-title":"Nanotechnology"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1088\/0957-4484\/17\/4\/003","article-title":"Vertically aligned carbon nanotube probes for monitoring blood cholesterol","volume":"17","author":"Roy","year":"2006","journal-title":"Nanotechnology"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"177","DOI":"10.1016\/S0302-4598(97)00088-3","article-title":"Direct electrochemistry of membrane-entrapped horseradish peroxidase. Part I A voltammetric and spectroscopic study","volume":"44","author":"Ferri","year":"1998","journal-title":"Bioelectrochem. Bioenergy"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1016\/j.jcis.2005.01.089","article-title":"Enzyme immobilization on poly(ethylene-co-acrylic acid) films studied by quartz crystal microbalance with dissipation monitoring","volume":"287","author":"Su","year":"2005","journal-title":"J. Colloid Interface Sci."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1635","DOI":"10.1016\/j.bios.2003.12.032","article-title":"Polyaniline\u2013uricase biosensor prepared with template process","volume":"19","author":"Kan","year":"2004","journal-title":"Biosensors Bioelectron."},{"key":"ref_12","first-page":"155","article-title":"Bioelectrochemical characteristics of glucose oxidase immobilized in a polyaniline film","volume":"3","author":"Mu","year":"1996","journal-title":"Sensors Actuators B"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1007\/BF01248249","article-title":"Krawczynsky vel Electrochemical biosensors based on enzymes immobilized in electropolymerized films","volume":"121","author":"Trojanowich","year":"1995","journal-title":"Microchim. Acta"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1416","DOI":"10.1002\/elan.1140091808","article-title":"A glucose amperometric sensor based on covalent immobilization of glucose oxidase in poly-2-aminoaniline film via chloranil on platinized platinum electrode","volume":"9","author":"Losada","year":"1997","journal-title":"Electroanalysis"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"445","DOI":"10.1016\/S0956-5663(00)00101-9","article-title":"Amperometric glucose biosensors based on Prussian Blue\u2014and polyaniline\u2013glucose oxidase modified electrodes","volume":"15","author":"Garjonyte","year":"2000","journal-title":"Biosensors Bioelectron"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1016\/j.aca.2005.02.059","article-title":"Carbon-nanotubes doped polypyrrole glucose biosensor","volume":"539","author":"Wang","year":"2005","journal-title":"Analytica Chimica Acta"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"522","DOI":"10.1002\/(SICI)1521-4095(200004)12:7<522::AID-ADMA522>3.0.CO;2-S","article-title":"Carbon nanotube and polypyrrole composites coating and doping","volume":"12","author":"Chen","year":"2000","journal-title":"Adv. Mater."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"136","DOI":"10.1002\/adma.200390027","article-title":"Polyaniline nanotubes doped with sulfonated carbon nanotubes made via a self-assembly process","volume":"15","author":"Wei","year":"2003","journal-title":"Adv. Mater."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"2408","DOI":"10.1021\/ja028951v","article-title":"Solubilization of carbon nanotubes by nafion towards the preparation of amperometric biosensors","volume":"125","author":"Wang","year":"2003","journal-title":"J. Am. Chem. Soc."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"689","DOI":"10.1016\/S1388-2481(03)00168-1","article-title":"Carbon nanotubes paste electrode","volume":"5","author":"Rubianes","year":"2003","journal-title":"Electrochem. Commun."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"132","DOI":"10.1002\/elan.200302931","article-title":"Solubilization of multiwall carbon nanotubes by 3-aminopropyltriethoxysilane towards the fabrication of electrochemical biosensors with promoted electron transfer","volume":"16","author":"Luong","year":"2004","journal-title":"Electroanalysis"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"877","DOI":"10.1016\/j.bios.2006.03.008","article-title":"Comparison of amperometric biosensors fabricated by palladium sputtering, palladium electrodeposition and Nafion\/carbon nanotube casting on screen-printed carbon electrodes","volume":"22","author":"Lee","year":"2007","journal-title":"Biosen. Bioelectron."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/9\/11\/8658\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T22:11:30Z","timestamp":1760220690000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/9\/11\/8658"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2009,10,29]]},"references-count":22,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2009,11]]}},"alternative-id":["s91108658"],"URL":"https:\/\/doi.org\/10.3390\/s91108658","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2009,10,29]]}}}