The self-assembly of polyacrylic acid nanoparticles induced by non-covalent interactions enhances the response of molecular fluorescent probes to formaldehyde†

Formaldehyde (FA) is a potent carcinogenic volatile organic compound, whose sensitive detection is crucial for environmental monitoring and human health. Herein, we present polymeric fluorescent supramolecular architectures for fine-tuning the environmental adaptability of FA fluorescent probes. Notably, our research demonstrates that in aqueous solutions, the common polymer polyacrylic acid (PAA) can self-assemble with the small-molecular FA fluorescent probe NBHN (N-butyl-4-hydrazido-1,8-naphthalimide) into hollow nanoparticles (referred to as PAA@NBHN), driven by hydrogen bonding interactions and π–π stacking. This process enhances FA fluorescence detection by improving probe sensitivity, response time, water solubility, and stability. Additionally, incorporating the fluorescent molecule MBNI (N-butyl-4-methoxy-1,8-naphthalimide) and dye cresyl violet in PAA@NBHN enables color-tunable fluorescence for FA detection, advancing visual colorimetric reagents and paper-based sensors. These exhibit potential for quantitative FA detection in both air and solution, while the hollow-spherical PAA particle architecture shows significant promise for innovative applications as water-soluble nanomaterials across various fields.