Gold nanoparticle electrochemical biosensors for cystatin C

Cystatin C (Cys C) has emerged as an essential biomarker for early diagnosis and monitoring of chronic kidney disease (CKD), demonstrating advantages over conventional markers such as creatinine. Electrochemical biosensors employing gold nanoparticles (AuNPs) offer significant promise for sensitive, selective, and rapid detection of Cys C due to their unique physicochemical properties, including high conductivity, excellent biocompatibility, large surface-to-volume ratio, and ease of surface functionalization. This mini-review systematically summarizes recent developments in AuNP-based electrochemical biosensors for Cys C detection, focusing specifically on immunosensors, enzyme-linked sensors, and nucleic acid-based sensors. We critically discuss sensor configurations, analytical performance, and novel strategies that enhance sensitivity and specificity. Despite the considerable advancements, several significant challenges remain, such as biofouling, reproducibility, limited clinical validation, and the need for standardized methodologies. The review concludes by highlighting essential future research directions aimed at overcoming these obstacles and facilitating the clinical translation of AuNP-based electrochemical biosensors for reliable Cys C analysis.