PVA-SM microstructure enhanced ratiometric fluorescence probe for formaldehyde detection in solution and gas.

Formaldehyde (FA) is one of the most common pollutants, which has tremendous harm to humans and environment. In this work, 4-amino-3-pentene-2-one (Fluoral-p) and SiO2 coated quantum dot (QD@SiO2) were combined to implement a new ratiometric fluorescence probe QD@SiO2-Fluoral-p for FA detection. In addition, by utilization of polyvinyl alcohol (PVA) and SiO2 microsphere (SM), a kind of PVA-SM microstructure was assembled with QD@SiO2-Fluoral-p to composite a signal enhanced sensing film. The QD@SiO2-Fluoral-p exhibited good response to 0-400 mg/L FA solution and an enhancement around 15 folds was realized after introducing PVA-SM. In both situations, the probe showed linear relationship to FA concentration (CFA), with detection limits of 14 and 0.5 mg/L, respectively. Also, the sensing film showed a good linear response to FA gas in the range of 0 to 2 ppm, with a detection limit 0.03 ppm. As a result, the PVA-SM enhanced ratiometric fluorescence probe features high sensitivity, low detection limit, good selectivity, as well as portable, which can serve as a useful tool for investigating FA in solution and gas at room temperature.