title: Ultrasensitive label free electrical detection of insulin in neat blood serum.
abstract: Electrical assays potentially offer a highly sensitive, cheap, portable, automated, and multiplexed means of protein biomarker detection, characteristics with an ability to underpin both disease stratification and the development of point of care diagnostics. Most conveniently applied in a reagent free manner, all sensitive assays such as these suffer, however, from profound problems when applied in complex fluids such as blood serum. We report herein, the development, and clinical application, of a highly sensitive and selective electrical insulin biosensor based on a chemisorbed zwittorionic polymer support and a novel reagentless sensing technique based on phase monitoring electrochemical impedance spectroscopy. The polymer adlayer is exceptionally effective in both reducing background response and maintaining receptive antibody binding efficacy, while the non-Faradaic analysis avoids potential interference from background electro-active molecules. Applied to the detection of even a low molecular weight protein (here, insulin), a linear range from 0.1 to 200 pM and an unprecedented femtomolar detection limit are possible in undiluted blood serum.
authors: Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK.
authors: Xiliang
authors: X
authors: Luo
authors: Mengyun
authors: M
authors: Xu
authors: Charlotte
authors: C
authors: Freeman
authors: Tim
authors: T
authors: James
authors: Jason J
authors: JJ
authors: Davis
mesh_terms: D000906:Antibodies / Q000737:chemistry*; D001622:Betaine / Q000737:chemistry; D015374:Biosensing Techniques / Q000295:instrumentation*; D002138:Calibration; D058266:Dielectric Spectroscopy / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D006046:Gold / Q000737:chemistry; D006801:Humans; D055767:Immobilized Proteins / Q000737:chemistry*; D007328:Insulin / Q000097:blood*; D057230:Limit of Detection; D019095:Point-of-Care Systems; D011109:Polymethacrylic Acids / Q000737:chemistry; D011485:Protein Binding
chemical_list: D000906:Antibodies; D055767:Immobilized Proteins; D007328:Insulin; D011109:Polymethacrylic Acids; C517178:polycarboxybetaine methacrylate; D001622:Betaine; D006046:Gold