CdS quantum dots: Bared for Oxytetracycline sensing and hyaluronic acid-functionalized bioimaging

In this paper, Ag + doped CdS quantum dots (Ag:CdS QDs) nanoprobes for obtaining near-infrared (NIR) nanoprobes for antibiotic detection and biological imaging were synthesized via an aqueous phase method based on CdS QDs. The emission wavelength of doped QDs was redshifted from visible region to NIR. Ag:CdS QDs nanoprobes have the characteristics of water solubility, uniform particle size, and fluorescence stability. When the nanoprobes are used to detect a certain concentration of Oxytetracycline (OTC), the fluorescence intensity will change accordingly. Ag:CdS QDs nanoprobes enabled rapid and sensitive detection to OTC within the range of 1.25 to 5.00 μM, the linear correlation equations were y = 29.9 x-18.541 (R 2  = 0.992), with a limit of detection (LOD) as low as 0.076 μM. The feasibility of this method was verified in fresh milk. At the same time, hyaluronic acid (HA) was coated on Ag:CdS QDs nanoprobes to improve the biocompatibility and obtained HA/Ag:CdS QDs nanoprobes that still retained good fluorescence properties and stability. Cell proliferation assay, red cell hemolysis assay, bioimaging experiment, and vivo imaging assay demonstrated that HA/Ag:CdS QDs nanoprobes possessed minimal cytotoxicity, excellent biocompatibility, and efficient cellular internalization via endocytosis, clearance capability, facilitating in vivo imaging. Therefore, Ag:CdS QDs nanoprobes can be used for detection OTC and HA/Ag:CdS QDs nanoprobes for bioimaging.