Bi-functional fluorescent polymer dots: a one-step synthesis via controlled hydrothermal treatment and application as probes for the detection of temperature and Fe3+

A one-step controlled hydrothermal method was described to prepare highly fluorescent polymer dots (PDs) by using polyethylene glycol as the carbon source. The synthesized PDs with an average diameter of 2.5 nm exhibit strong blue fluorescence with high quantum yields (QYs, up to 19%). Further modification of these PDs with glutathione (GSH) endows the resultant GSH–PDs with bi-functional fluorescence responses to temperature and Fe3+. Interestingly, the fluorescence signal of the GSH–PDs is reversibly responsive to the environmental temperature in the range of 20–75 °C. As the GSH–PDs exhibit good biocompatibility, they can pervade the MC3T3-E1 cells and enable the measurement of temperature over the physiological range of 20–45 °C using the confocal fluorescence imaging method. The GSH–PDs were also explored as a fluorescent probe for Fe3+ ion detection, and the linear response range in 0.1–10 μM was observed with a detection limit of 3.7 nM. Thus, the bi-functional measurement of temperature and Fe3+ ions was achieved by the fluorescent PD chemosensor.