Microwave-assisted synthesis of polymer nanoparticles with physically entrapped fluorophores

Microwave irradiation has emerged as a highly advantageous alternative to conventional heating methods, with well-documented merits in the synthesis of diverse nanomaterials, including fluorescent nanomaterials. However, its potential for enabling the rational fabrication of fluorescent polymer nanoparticles (FPNs) with precisely tunable size, fluorescence wavelength, and brightness, a critical requirement for their broad practical applications, remains underexplored. Here, we present a microwave-assisted strategy for the rapid preparation of FPNs incorporating physically entrapped fluorophores, using monomer emulsions pre-doped with dye molecules as precursors. By systematically modulating the concentrations of salt and surfactant, the type and loading of fluorophores, and the monomers prior to polymerization, we achieve precise control over dye–dye interactions, energy transfer processes, and the local microenvironment within the FPNs. This approach enables fine-tuning of FPN size, emission wavelength, and fluorescence brightness while endowing the nanoparticles with thermoresponsive properties. We anticipate that this facile and efficient FPNs fabrication protocol will facilitate the large-scale production and practical deployment of these functional fluorescent nanomaterials.