Silver Nanoparticles: Synthesis, Characterization, and Quartz Crystal Microbalance (QCM)-Based Sensing Application for Vitamin D3

This study details the synthesis, characterization, and application of silver nanoparticles (AgNPs) for the sensitive detection of vitamin D3 using a quartz crystal microbalance (QCM) platform. AgNPs were synthesized via chemical reduction and characterized by XRD, AFM, DLS, and zeta-potential analysis, revealing an average hydrodynamic size of 32 nm and a zeta potential of −30.2 mV, indicating excellent colloidal stability. Complementary FT-IR, SEM, and TEM confirmed a polymer capping layer and predominantly spherical morphology. Integrated into a QCM sensor, the AgNPs produced a dose-dependent frequency shift to vitamin D3 with a quantitative linear range of 0.5–10 μg mL⁻¹ (working range 0.5–50 μg mL⁻¹), a limit of detection (LOD) of 0.25 μg mL⁻¹, and a limit of quantification (LOQ) of 0.83 μg mL⁻¹. Practical applicability was verified in spiked serum, achieving 92–98% recovery. These results establish the AgNP–QCM platform as a robust, rapid, and cost-effective sensor for vitamin D3 determination with strong potential for pharmaceutical and clinical applications.