Amines play vital roles in agricultural, pharmaceutical, and food industries, but volatile amine vapors are serious threats to human health. Previously reported fluorescent sensors for amine vapor detection usually suffer from aggregation-caused quenching (ACQ) effect and need to be dispersed in solution or matrix materials. Herein, based on the fluorogen of 2-(2-hydroxyphenyl)quinazolin-4(3H)-one (HPQ) with aggregation-induced emission (AIE) properties, we have developed a fluorescent sensor HPQ-Ac for light-up detection of amine vapors through aminolysis reaction. The portable HPQ-Ac sensor can be easily prepared by directly depositing on filter paper, and it can only light up via exposure to amine vapors among various volatile organic compounds. Taking advantage of its portability and high sensitivity for amine vapors, HPQ-Ac sensor can also be used for food spoilage detection and fluorescent invisible ink.

Anionic surfactants are widely used in daily life and industries, but their residues can cause serious damage to the environment. The current detection methods for anionic surfactants suffer from various limitations and a new detection strategy is highly desirable. Based on 2-(2-hydroxyphenyl)benzothiazole fluorogen with aggregation-induced emission characteristics, we have developed a fluorescent probe HBT-C18 for selective and sensitive detection of anionic surfactants. By in situ formation of catanionic aggregates or micelles with anionic surfactants, the emission intensity of the HBT-C18 probe can increase with increasing keto/enol emission ratio through restriction of intramolecular motion and excited-state intramolecular proton-transfer mechanisms. The probe can also be used for wash-free imaging of bacteria enveloped by a negatively charged outer membrane. The results of this study provide a new strategy for sensitive detection of anionic surfactants and wash-free bacterial imaging.