A Bifunctional Nanosilver-Reduced Graphene Oxide Nanocomposite for Label-Free Electrochemical Immunosensing

Supakeit Chanarsa; Jaroon Jakmunee; Kontad Ounnunkad

doi:10.3389/fchem.2021.631571

A Bifunctional Nanosilver-Reduced Graphene Oxide Nanocomposite for Label-Free Electrochemical Immunosensing

Front Chem. 2021 Apr 28:9:631571. doi: 10.3389/fchem.2021.631571. eCollection 2021.

Authors

Supakeit Chanarsa^{1

2}, Jaroon Jakmunee^{1

3}, Kontad Ounnunkad^{1

3

4}

Affiliations

¹ Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand.
² The Graduate School, Chiang Mai University, Chiang Mai, Thailand.
³ Research Center on Chemistry for Development of Health Promoting Products From Northern Resources, Chiang Mai University, Chiang Mai, Thailand.
⁴ Center of Excellence in Materials Science and Technology, Chiang Mai University, Chiang Mai, Thailand.

Abstract

A bi-functional material based on silver nanoparticles (AgNPs)-reduced graphene oxide (rGO) composite for both electrode modification and signal generation is successfully synthesized for use in the construction of a label-free electrochemical immunosensor. An AgNPs/rGO nanocomposite is prepared by a one-pot wet chemical process. The AgNPs/rGO composite dispersion is simply cast on a screen-printed carbon electrode (SPCE) to fabricate the electrochemical immunosensor. It possesses a sufficient conductivity/electroreactivity and improves the electrode reactivity of SPCE. Moreover, the material can generate an analytical response due to the formation of immunocomplexes for detection of human immunoglobulin G (IgG), a model biomarker. Based on electrochemical stripping of AgNPs, the material reveals signal amplification without external redox molecules/probes. Under optimized conditions, the square wave voltammetric peak current is responded to the logarithm of IgG concentration in two wide linear ranges from 1 to 50 pg.ml^-1 and 0.05 to 50 ng.ml^-1, and the limit of detection (LOD) is estimated to be 0.86 pg.ml^-1. The proposed immunosensor displays satisfactory sensitivity and selectivity. Importantly, detection of IgG in human serum using the immunosensor shows satisfactory accuracy, suggesting that the immunosensor possesses a huge potential for further development in clinical diagnosis.

Keywords: Immunoglobulin G; electrochemistry; immunosensor; reduced graphene oxide; screen-printed carbon electrode; silver nanoparticles.