A silica coated AgNCs fluorescence sensor for detection of cefixime in pharmaceutical products and biological samples

The confinement effect of silica nanoparticles (SNPs) can significantly enhance the fluorescence and sensing performance of metal nanoclusters. In this study, silver nanoclusters (Ag NCs) were encapsulated within silica nanoparticles (SNPs) via a reverse microemulsion method to form a silver nanoclusters/silica nanoparticles (Ag NCs/SNPs) composite. The composite exhibited superior fluorescence properties compared to bare Ag NCs. It was found that cefixime (Cfx) could effectively quench the fluorescence of Ag NCs/SNPs (λ_ex = 265 nm; λ_em = 298 nm). Based on this, a novel fluorescence method was developed for the detection of Cfx. Under optimal conditions, the probe showed a linear response to Cfx concentrations ranging from 0.77 to 24.4 µmol L^-1, with a limit of detection (LOD) of 0.37 µmol L^-1 (LOQ = 1.23 µmol L^-1). The method demonstrates high selectivity for Cfx against common interferents. When applied to the analysis of pharmaceutical samples and human serum sample, the method yielded satisfactory recovery rates of 92.57-109.83% and 93.73-102.05%, respectively, with relative standard deviations (RSD) below 6.51%. These results confirm that the proposed sensing system is robust and reliable, indicating its great potential for application in pharmaceutical quality control and the detection of Cfx in biological samples.