Microwave-assisted facile synthesis of polymer dots as a fluorescent probe for detection of cobalt(II) and manganese(II).

Polymer dots (PDs) were synthesized at 200 °C for 90 min via a microwave-assisted method. The PDs were characterized by fluorescence spectroscopy, UV-vis absorbance spectra, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The PDs display blue fluorescence under 320 nm excitation with a fluorescent quantum yield of 13.48%. The PDs show stable fluorescence against ion strength and light bleaching, especially extreme pH. Significant pH-independent behavior may relate to -OH of polyvinyl alcohol (PVA) retained on the surface of PDs. The bright fluorescence of PD solution can be distinctly quenched by cobalt ion (Co2+) and manganese ion (Mn2+) in PD solution. For Co2+, the linear was from 3.4 to 50.0 μmol L-1 and 46.7 to 600.0 μmol L-1 with the limit of detection (LOD) of 1.0 μmol L-1. The LOD of Mn2+ was 0.4 μmol L-1 in the range from 1.5 to 100.0 μmol L-1. Self-film-forming PDs (FPDs) were obtained via dropping PD solution on quartz glass. The bright blue fluorescence of FPDs can be obviously quenched by Co2+ and Mn2+. This paper may provide an efficient and flexible approach to the application of on-site detection. Graphical abstract Graphical abstract.