A Renewable Amperometric Immunosensor for hs-CRP Based on Functionalized Fe<sub>3</sub>O<sub>4</sub>@Au Magnetic Nanoparticles Attracted on Fe (III) Phthlocyanine/Chitosan-Membrane Modified Screen-Printed Carbon Electrode by a Magnet

Abstract

A novel disposable screen-printed immunosensor for rapid determination of highly sensitive C reactiveprotein (hs-CRP) in human serum has been developed in the experiment. The sensor was constructed on one screen-printed carbon electrode (SPCE) with HRP labeled anti-hs-CRP antibody functionalized Fe3O4@Au magnetic nanoparticles (HRP labeled anti hs-CRP/ Fe3O4@Au) as the biorecognition probes attracted on the surface of Fe (III) phthalocyanine (FePc)/ chitosan membrane modified screen-printed carbon electrode (SPCE|FePc/Chit/chitosan) by external magnetic field. FePc was acted as electron immediate. The modified electrode shows an excellent electrocatalytic activity for hs-CRP in phosphate buffer solution (pH=7.0). After the immunosensor is incubated with hs-CRP antigen solution at 37°C for 20 min, the access of activity center of the HRP to electrode is partly inhibited, which leads to a linear decrease of the catalytic efficiency of the HRP to the reduction of immobilized FePc by H2O2 at –50 mV in hs-CRP’s concentration ranges from 1.2 to 200 ng/mL. The detection limit was 0.5ng/mL. The immunosensor was successfully utilized for determination of hs-CRP in real serum samples of heart disease patients, whose results were consistent with that by ELISA method. The accuracy and precision of the assay were 91.5-104.4% and 15.8-24.4%, respectively. The immunosensor was reusable once constructed and can be regenerated by adding new nanoprobes on the surface of basal electrode through magnet on its bottom. It can greatly reduce the detection cost which is valuable for the early diagnosis of tumors.