title: Silver-functionalized g-C3N4 nanohybrids as signal-transduction tags for electrochemical immunoassay of human carbohydrate antigen 19-9.
abstract: A simple and feasible electrochemical immunosensing platform was developed for highly efficient screening of a disease-related protein (human carbohydrate antigen 19-9, CA 19-9 used in this case) using silver-functionalized g-C3N4 nanosheets (Ag/g-C3N4) as signal-transduction tags. Initially, Ag/g-C3N4 nanohybrids were synthesized by combining thermal polymerization of the melamine precursor with the photo-assisted reduction method. Thereafter, the as-synthesized Ag/g-C3N4 nanohybrids were utilized for the labeling of the anti-CA 19-9 detection antibody by using a typical carbodiimide coupling method. The assay was carried out on a capture antibody-modified glassy carbon electrode in a sandwich-type detection mode. The detectable signal mainly derived from the voltammetric characteristics of the immobilized nanosilver particles on the g-C3N4 nanosheets within the applied potentials. Under the optimal conditions, the voltammetric peak currents increased with the increasing amount of target CA 19-9, and exhibited a wide linear range from 5.0 mU mL(-1) to 50 U mL(-1) with a detection limit of 1.2 mU mL(-1). Our strategy also displayed good reproducibility, precision and specificity. The results of the analysis of clinical serum specimens were in good accordance with the results obtained by an enzyme-linked immunosorbent assay (ELISA) method. The newly developed immunosensing system is promising for enzyme-free and cost-effective analysis of low-abundance proteins.
authors.affiliation: Department of Chemistry and Chemical Engineering, Xinxiang University, Xinxiang 453000, P.R. China. sunaili77@yeah.net.
authors.forename: Ai-Li
authors.initials: AL
authors.lastname: Sun
authors.forename: Qing-An
authors.initials: QA
authors.lastname: Qi
mesh_terms: D018395:CA-19-9 Antigen / Q000032:analysis*; D055664:Electrochemical Techniques; D006046:Gold; D006801:Humans; D007118:Immunoassay; D057230:Limit of Detection; D053768:Metal Nanoparticles; D015203:Reproducibility of Results; D015398:Signal Transduction; D012834:Silver
chemical_list: D018395:CA-19-9 Antigen; D012834:Silver; D006046:Gold