Silver nanoparticle-modified plastic chip electrodes for impedimetric detection of vaspin

Vaspin, a serine protease inhibitor, is emerging as a promising biomarker for the early diagnosis of type 2 diabetes (T2D), cardiovascular disorders, and obesity-related metabolic dysfunction. Conventional detection methods-such as optical and chemical assays-often require expensive instrumentation, trained personnel, and are time-consuming. In this study, we report the development of a low-cost, sensitive, and rapid electrochemical biosensor based on plastic chip electrodes modified with spherical silver nanoparticles (AgNPs) for the impedimetric detection of vaspin. The AgNPs were synthesized through a cost-effective chemical route and characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD) to confirm their morphology, size, and crystallographic planes. Successful immobilization of vaspin onto the AgNP-modified surface was validated by energy-dispersive X-ray spectroscopy (EDX) and Raman spectroscopy. Electrochemical impedance spectroscopy (EIS) was employed to monitor changes in interfacial properties at each stage of electrode modification. The fabricated impedimetric sensor demonstrated excellent sensitivity and linearity for vaspin detection in aqueous, achieving a limit of detection (LOD) in the picomolar 0.52 pM range.