title: Multiple signal amplification strategies for ultrasensitive label-free electrochemical immunoassay for carbohydrate antigen 24-2 based on redox hydrogel.
abstract: In this work, multiple signal amplification strategies for ultrasensitive label-free electrochemical immunoassay for carbohydrate antigen 24-2 (CA242) were developed using redox sodium alginate-Pb2+-graphene oxide (SA-Pb2+-GO) hydrogel. The SA-Pb2+-GO hydrogel was synthesised by simply mixing SA, GO, and Pb2+and then implemented as a novel redox species with a strong current signal at -0.46V (vs. Ag/AgCl). After the three-dimensional and porous SA-Pb2+-GO hydrogel was in situ generated on a glassy carbon electrode (GCE), chitosan was adsorbed on the obtained electrode to further enrich Pb2+. When chitosan-Pb2+/SA-Pb2+-GO/GCE was incubated with anti-CA242 using glutaraldehyde and blocked by bovine serum albumin, the immunoassay platform for CA242 was obtained. Owing to the addition of GO, the obtained conductive SA-GO/GCE was beneficial for signal amplification. After incubating SA-GO/GCE with excessive amounts of Pb2+, the resistance of SA-Pb2+-GO/GCE further decreased and a strong redox signal was obtained. The chitosan fixed by electrostatic adsorption resulted in further adsorption of Pb2+, behaving as further amplifying the signal and improving conductivity. In this case, multiple signal amplification strategies were involved in the proposed immunosensor for the ultrasensitive detection of CA242. Under the optimal conditions, the proposed immunosensor exhibited a wide linear range from 0.005UmL-1to 500UmL-1with an ultralow detection limit of 0.067mUmL-1. In comparison to previous works, the sensitivity of this method was 32.98μA (log10CCA242)-1, which was a five-fold increase from the previous works.
authors.affiliation: Department of Chemistry, Capital Normal University, Beijing 100048, China.
authors.forename: Zhongxue
authors.initials: Z
authors.lastname: Tang
authors.affiliation: Department of Chemistry, Capital Normal University, Beijing 100048, China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Fu
authors.affiliation: Department of Chemistry, Capital Normal University, Beijing 100048, China. Electronic address: mazhanfang@cnu.edu.cn.
authors.forename: Zhanfang
authors.initials: Z
authors.lastname: Ma
mesh_terms: D000464:Alginates / Q000737:chemistry*; D055910:Antibodies, Immobilized / Q000737:chemistry*; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000097:blood*; D015374:Biosensing Techniques / Q000379:methods; D048271:Chitosan / Q000737:chemistry; D055664:Electrochemical Techniques / Q000379:methods*; D020723:Glucuronic Acid / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D006603:Hexuronic Acids / Q000737:chemistry; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D007118:Immunoassay / Q000379:methods; D007854:Lead / Q000737:chemistry*; D057230:Limit of Detection; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry
chemical_list: D000464:Alginates; D055910:Antibodies, Immobilized; D015295:Antigens, Tumor-Associated, Carbohydrate; C074601:CA 242 antigen; D006603:Hexuronic Acids; D010087:Oxides; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D007854:Lead; D006108:Graphite; D020723:Glucuronic Acid; D048271:Chitosan
keywords: Carbohydrate antigen 24-2; Chitosan; Electrochemical immunoassay; Hydrogel; Sodium alginate; Sodium alginate-Pb(2+)-graphene oxide