title: A Urea Potentiometric Biosensor Based on a Thiophene Copolymer.
abstract: A potentiometric enzyme biosensor is a convenient detector for quantification of urea concentrations in industrial processes, or for monitoring patients with diabetes, kidney damage or liver malfunction. In this work, poly(3-hexylthiophene-co-3-thiopheneacetic acid) (P(3HT-co-3TAA)) was chemically synthesized, characterized and spin-coated onto conductive indium tin oxide (ITO) glass electrodes. Urease (Urs) was covalently attached to the smooth surface of this copolymer via carbodiimide coupling. The electrochemical behavior and stability of the modified Urs/P(3HT-co-3TAA)/ITO glass electrode were investigated by cyclic voltammetry, and the bound enzyme activity was confirmed by spectrophotometry. Potentiometric response studies indicated that this electrode could determine the concentration of urea in aqueous solutions, with a quasi-Nernstian response up to about 5 mM. No attempt was made to optimize the response speed; full equilibration occurred after 10 min, but the half-time for response was typically <1 min.
authors.affiliation: Materials Research Centre & School of LSPC, Faculty of Science, Engineering and Computing, Kingston University London, Penrhyn Road, Kingston upon Thames, Surrey KT1 2EE, UK. kevinla.lai@msa.hinet.net.
authors.forename: Cheng-Yuan Kevin
authors.initials: CK
authors.lastname: Lai
authors.affiliation: Materials Research Centre & School of LSPC, Faculty of Science, Engineering and Computing, Kingston University London, Penrhyn Road, Kingston upon Thames, Surrey KT1 2EE, UK. p.j.foot@kingston.ac.uk.
authors.forename: Peter J S
authors.initials: PJ
authors.lastname: Foot
authors.affiliation: Materials Research Centre & School of LSPC, Faculty of Science, Engineering and Computing, Kingston University London, Penrhyn Road, Kingston upon Thames, Surrey KT1 2EE, UK. j.brown@kingston.ac.uk.
authors.forename: John W
authors.initials: JW
authors.lastname: Brown
authors.affiliation: Materials Research Centre & School of LSPC, Faculty of Science, Engineering and Computing, Kingston University London, Penrhyn Road, Kingston upon Thames, Surrey KT1 2EE, UK. p.spearman@kingston.ac.uk.
authors.forename: Peter
authors.initials: P
authors.lastname: Spearman
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D002138:Calibration; D002234:Carbodiimides / Q000737:chemistry; D055664:Electrochemical Techniques; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000737:chemistry; D005898:Glass; D006801:Humans; D006863:Hydrogen-Ion Concentration; D011108:Polymers / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012996:Solutions; D013876:Thiophenes / Q000138:chemical synthesis / Q000737:chemistry*; D017971:Tin Compounds / Q000737:chemistry*; D014508:Urea / Q000032:analysis*; D014510:Urease / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D002234:Carbodiimides; D004800:Enzymes, Immobilized; D011108:Polymers; D012996:Solutions; D013876:Thiophenes; D017971:Tin Compounds; D014867:Water; C109984:indium tin oxide; D014508:Urea; D014510:Urease
keywords: biosensors; conducting polymer; polythiophene; potentiometry; urea; urease