Construction of electrochemical immunosensors based on redox hydrogels for ultrasensitive detection of carcinoembryonic antigens

• Published in: New journal of chemistry 2021-06, Vol.45 (24), p.188-1889
• Main Authors: Huang, Xiangrong, Wu, Na, Liu, Wenxiu, Shang, Yazhuo, Liu, Honglai, He, Yifan, Meng, Hong, Dong, Yinmao
• Format: Article
• Language: English
• Subjects: Antibodies; Antigens; Electrochemical analysis; Glassy carbon; Gold; Graphene; Hydrogels; Hydrophobicity; Immunoassay; Immunosensors; Methylene blue; Multi wall carbon nanotubes; Nanocrystals; Nanoparticles; Reliability analysis; Selectivity; Serum albumin; Signal to noise ratio; Silver chloride; Stability analysis
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d1nj01282g

In this work, a novel redox hydrogel was proposed for ultrasensitive label-free electrochemical detection of a carcinoembryonic antigen (CEA). The redox hydrogel composed of cellulose nanocrystals (CNCs), methylene blue (MB), multi-walled carbon nanotubes (MWCNTs), and polydopamine-reduced graphene oxide-gold nanoparticles (PDA-rGO-AuNPs) was formed by electrostatic and hydrophobic interactions among these components. The larger surface to volume ratio, outstanding hydrophilicity, excellent film-forming ability and the gelatinization of CNCs provided the premise for the formation of a gel with excellent properties including larger specific surface area (101.05 m 2 g −1 ), better adhesive ability to glassy carbon electrodes (GCEs), etc. The addition of MWCNTs to hydrogel could improve the adsorption of redox MB. The synthesized PDA-rGO-AuNPs gel was integrated into a hydrogel not only for improving the conductivity but also for providing more sites for immobilization of antibodies. The obtained CNC-MB-MWCNT-PDA-rGO-AuNPs gel was then applied to modify GCE and the gel/GCE demonstrated higher stability and exhibited a strong redox performance (current signal appeared at −0.156 V ( vs. Ag/AgCl)). The immunoassay platform was constructed after the gel/GCE was incubated with anti-CEA and blocked by bovine serum albumin (BSA) in succession. The proposed immunosensor exhibited a wider linear range from 1 fg mL −1 to 200 ng mL −1 with an ultralow detection limit of 0.011 fg mL −1 (at a signal to noise ratio of 3). Furthermore, the immunosensor demonstrated higher selectivity, excellent reproducibility, remarkable stability, and better reliability for real sample analysis, which implied a promising potential for the determination of CEA in clinical application. The introduction of cellulose nanocrystals (CNCs) endows a redox hydrogel with a larger specific surface area and better adhesion to an electrode.