Quenching of Fluorescence Caused by Graphene Oxide as an Immunosensing Platform in a Microwell Plate Format

Abstract

Immunoassays are, at present, an important tool for diagnostics, drug development, and environmental monitoring. However, most immunoassays involve procedures that require many elements for their development. We introduce a novel biosensing platform based on fluorescence quenching caused by graphene oxide (GO) for the detection of Human-IgG and Prostate-Specific Antigen (PSA). We employ a single antibody for the capture and detection processes, avoiding washing steps. FITC fluorophore was conjugated with antibodies for H-IgG detection, whereas quantum dots were conjugated with antibodies for PSA detection. The simple biosensing platform consists of covering a 96-well microplate (with a polystyrene bottom) with GO. The graphene oxide adhesion is possible by way of electrostatic interactions between the plate surface modified with amino groups (positively charged) and the graphene oxide (negatively charged). This proposal showed an excellent response for the detection of Human-IgG, with acceptable precision (from 0.27% to 5%). The limit of detection reached for H-IgG was 3.35 ng mL-1. In the same manner, for PSA detection, the limit of detection reached was 0.02 ng mL-1 and the precision range was from 0.7% to 15.2%. Furthermore, this biosensing platform was demonstrated to operate with real samples of human urine doped with different concentrations of prostate-specific antigen.