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.

In recent times, there has been a significant rise in global arsenic intake, stemming from both drinking water and food sources. Arsenic contamination in groundwater can originate from natural geological processes as well as industrial effluents, agricultural practices such as insecticide use, municipal sewage, and household waste.One eco-friendly and dependable method for addressing this issue involves the synthesis of metal complex nanoparticles, which has broad applications in various fields. A noteworthy development is the creation of a novel nano chromium sensor designed specifically for detecting arsenic. This nano chromium complex underwent comprehensive characterization using a range of analytical tools, including Dynamic Light Scattering (DLS), Zeta potential analysis, Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), Fourier-Transform Infrared Spectroscopy (FT-IR), contact angle measurements, as well as BET surface area and pore size determination.Furthermore, researchers explored the practical application of the nano chromium complex as a simple, cost-effective, and highly sensitive Quartz Crystal Microbalance (QCM) sensor for the rapid detection of arsenic. Using this nano chromium complex sensor, arsenic can be reliably detected even at extremely low concentrations, as low as 1 ppm, with a remarkable response time of just 1 minute. Additionally, the cytotoxicity of the arsenic complex nanoparticles was thoroughly investigated to ensure their safety.This innovative method has demonstrated its effectiveness and feasibility for the precise determination of arsenic ions in samples from groundwater and industrial effluent wastewater.