Development of a new phosphorescence sensor based on surface molecularly imprinted Mn-doped ZnS quantum dots for detection of melamine in milk products

This paper presents a novel room temperature phosphorescence sensor (IMIPs-ZnS QDs RTP sensor) based on inorganic surface molecularly imprinted polymers and Mn-doped ZnS quantum dots (QDs) for the rapid detection of trace melamine (MEL) in commercial milk products. The surface of Mn-ZnS QDs was modified with 3-(mercaptopropyl) trimethoxy silane (MPTS). Then, MEL, 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) were used as a template/target molecule, functional monomer, and cross-linker, respectively. IMIPs-ZnS QDs RTP sensor was characterized using spectrofluorimeter, UV–Vis spectrophotometer, FT-IR, transmission electron microscope (TEM), and X-ray photoelectron spectrometer (XPS). Detection time and linear range for IMIPs-ZnS QDs RTP sensor were 30 min and 4.0–79.2 µM with a correlation coefficient value of 0.9946, respectively. Furthermore, LOD and LOQ values were calculated using Stern-Volmer equation as 0.29 and 0.97 µM, respectively. Thus, IMIPs-ZnS QDs RTP sensor was successfully applied for the detection of MEL residue in milk samples. Recovery values were in the range of 88.62–90.22 % with relatively high precision values (0.57–0.92 % RSD). Our findings indicate that the developed IMIPs-ZnS QDs RTP sensor exhibits high sensitivity and selectivity towards the MEL in milk sample containing potentially relatively high number of interfering compounds.