Immunosensing the rheumatoid arthritis biomarker through bifunctional aldehyde-amine linkers on an iron oxide nanoparticle seeded voltammetry sensor

An immunosensor was developed on an interdigitated electrode (IDE) by voltammetry sensing for the early identification of the autoimmune disease ‘rheumatoid arthritis (RA)’ by detecting the biomarker anti-cyclic citrullinated peptide antibody (anti-CCP). Higher immobilization of cyclic citrullinated peptide (CCP) as a probe was achieved by using green synthesized iron oxide nanoparticles (IONPs). Field-emission scanning electron microscopy and field-emission transmission electron microscopy observations revealed that the polydispersed material displayed multifaceted features. X-ray photoelectron spectroscopy analysis confirms the occurrence of Fe, O, and C groups on the synthesized IONPs. IONPs were immobilized with a probe on IDE through bifunctional aldehyde-amine linkers. Due to the elevated occupancy of CCP and the highly efficient electric transfer from IONPs, higher changes in current are observed upon binding of anti-CCP with CCP. In the linear range from 8 to 250 pg/mL, the sensitivity and detection limit of anti-CCP were 8 and 15 pg/mL, respectively, with a regression coefficient of y = 1E−06x−3E−07; R2 = 0.9637. Control experiments with nonimmune antibody and anti-carcinoembryonic antigen indicate the specific detection of anti-CCP. Furthermore, spiking of anti-CCP in human serum does not interfere, representing the specific detection of anti-CCP. This CCP-immobilized IDE through IONP helps to quantify anti-CCP levels in the biological fluid for diagnosing RA.