Novel Nanosensors Represented by Cds/Zns Quantum Dots Doped with Manganese (Ii) Ions for Detection of Vancomycin

Abstract

This paper demonstrates potential for analytical nanosensoring offered by core-shell CdS/ZnS and CdS/ZnS quantum dots (QDs) doped with manganese (II) ions for rapid detection of a glycopeptide antibiotic vancomycin (VNC) in aqueous media by luminescence quenching. “Core-shell” quantum dots were synthesized by colloidal method and hydrophilized by mercaptopropionic acid (MPA). To reveal the mechanism for luminescence quenching of these nanosensors, we studied spectral characteristics of QDs and VNC and revealed a complex influence of VNC on the luminescence quenching of CdS/ZnS and Cd0.9Mn0.1S/ZnS nanoparticles. We performed quantum chemical calculations of the equilibrium geometry and IR spectra of the VNC-MPA system and the bond energies in the CdS/ZnS–MPA–VNC system. The luminescence quenching of CdS/ZnS QDs by vancomycin was shown to linearly depend on its concentration in the 35–690 µM range with the determination coefficient R2 = 0.988. The luminescence quenching of Cd0.9Mn0.1S/ZnS QDs was linearly sensitive to vancomycin in the narrower concentration range of 0–207 µM with the determination coefficient R2 = 0.999. The detection thresholds of vancomycin were found to be 56.2 µM and 1.9 µM by CdS/ZnS QDs and CdS/ZnS QDs doped with Mn (II) ions, respectively.

Keywords: quantum dots, nanosensor, vancomycin, luminescence quenching, Stern-Volmer constants, quantum chemical modeling