ZnSe:Mn aqueous colloidal quantum dots for optical and biomedical applications

In this study, we present the optimization of the optical properties of Mn2+ doped ZnSe QDs (also referred to as d-dots) coated with thioglycolic acid in aqueous medium. The nanoparticles were characterized by ionic coupled plasma, electron paramagnetic resonance, transmission electron microscopy and X-ray diffractometry. By applying a controlled dose of UV irradiation, we obtained efficient orange emitting d-dots (T-4(1)-> (6)A(1) transition centered at 580 nm). The results point out to a doping fraction in the nanoparticles smaller than 1% (0.89%), and that the Mn2+ ions are preferentially located close to the particle's surface. The UV photoactivation procedure has a definite influence on the emission intensity and on the colloidal stability of the particles. Photoactivated Mn2+ d-dots were conjugated to Concanavalin A and labeled specifically Candida albicans yeast cells, by targeting carbohydrate residues depicting the successful use of these QDs as fluorescent probes. (C) 2016 WILEY-VCH Verlag GmbH & Co.