A fluorescence-enhanced inverse opal sensing film for multi-sources detection of formaldehyde

The SiO₂ inverse opal photonic crystals (PC) with a three-dimensional macroporous structure were fabricated by the sacrificial template method, followed by infiltration of a pyrene derivative, 1-(pyren-8-yl)but-3-en-1-amine (PEA), to achieve a formaldehyde (FA)-sensitive and fluorescence-enhanced sensing film. Utilizing the specific Aza-Cope rearrangement reaction of allylamine of PEA and FA to generate a strong fluorescent product emitted at approximately 480 nm, we chose a PC whose blue band edge of stopband overlapped with the fluorescence emission wavelength. In virtue of the fluorescence enhancement property derived from slow photon effect of PC, FA was detected highly selectively and sensitively. The limit of detection (LoD) was calculated to be 1.38 nmol/L. Furthermore, the fast detection of FA (within 1 min) is realized due to the interconnected three-dimensional macroporous structure of the inverse opal PC and its high specific surface area. The prepared sensing film can be used for the detection of FA in air, aquatic products and living cells. The very close FA content in indoor air to the result from FA detector, the recovery rate of 101.5% for detecting FA in aquatic products and fast fluorescence imaging in 2 min for living cells demonstrate the reliability and accuracy of our method in practical applications.