A universal strategy for the fabrication of single-photon and multiphoton NIR chromophore nanoparticles by loading organic dyes into water-soluble polymer nanosponges

The development of optical organic nanoparticles (NPs) is desirable and widely studied. However, most organic chromophores are water-insoluble, and therefore, the derivatization and modification of these chromophores are difficult. Herein, we demonstrated a simple platform for the fabrication of organic nanoemitters by loading ten different organic dyes (molar masses of 479.1-1081.7 g/mol) into water-soluble polymer nanosponges composed of poly(styrene-alt-maleic acid) (PSMA). This nanolization strategy enables the incorporation of small commercial dyes (3.7–50% loading) and newly synthesized large photosensitive molecules (> 85% loading) into PSMA NPs and prevents the spontaneous aggregation of these hydrophobic chromophores in aqueous solutions. These low-cytotoxicity organic nanoparticles exhibited tunable red to near-infrared fluorescence emission for cellular imaging and biological tracking in vivo. Moreover, PSMA NPs loaded with designed NIR-photosensitive molecules were fabricated, and photodynamic therapy with these dye-loaded PSMA NPs for the photolysis of cancer cells was achieved when coupled with 808 nm laser excitation. Indeed, our work demonstrates a facile approach for increasing the biocompatibility and stability of organic dyes by loading them into water-soluble polymer-based carriers, providing a new perspective of organic optoelectronic materials in biomedical theranostic applications.