The fiber optic SPR cholesterol biosensor based on electroless silver plating film

Cholesterol, as a crucial biomarker of human health, has been extensively studied; however, its low-concentration monitoring in sebum secretion and sweat remains largely unexplored. This study leverages the simple, low-cost, and easy-to-operate electroless silver plating method to maximize the advantages of a label-free, miniaturized biosensor based on surface plasmon resonance (SPR). This study employs a simple, low-cost, and user-friendly electroless silver plating method to enhance the performance of a label-free, miniaturized biosensor based on surface plasmon resonance (SPR). By optimizing the plating time, a high sensitivity of 3261.18 nm/RIU was achieved within the refractive index (RI) range of 1.333 to 1.390. The sensor utilizes the strong adhesion of polydopamine (PDA) to enable the rapid fabrication of functional layers. In the cholesterol concentration range of 0–1.00 $\text{μ}\text{M}$, the sensor exhibited a high detection sensitivity of up to 133.83 nm/$\text{μ}\text{M}$, with a detection limit as low as 0.0051 $\text{μ}\text{M}$. Compared to the cholesterol biosensor modified with graphene oxide (GO), the sensor exhibited a larger average wavelength shift (45.29 nm) and a 2.01-fold improvement in detection sensitivity. This biosensor exhibits excellent selectivity for cholesterol and shows promise for clinical applications involving biomedical samples, particularly by addressing the lack of efficient cholesterol detection in sebum.