Bright and White Light-Triggered Aggregation-Induced Emission Nanoparticles Prepared in Miniemulsions for Photodynamic Theranostics

The development of a nanotherapeutic platform integrating fluorescence with photodynamic therapy (PDT), namely, fluorescence-guided PDT, is of great significance for the precise and noninvasive detection and treatment of major diseases such as cancers. In this work, polymer nanoparticles (PNPs) with dual functions of aggregation-induced emission (AIE) and PDT were conveniently synthesized via miniemulsion copolymerization by integrating the dually functionalized monomer allyl (E) 3-(5′-[4″-(diphenylamino)phenyl-5″-yl]thiophen-2′-yl)-2-cyanoacrylate (TTCy) into the polymer matrix of PNPs (TTCy-PNPs). The TTCy molecules with a donor−π–acceptor structure displayed a typical AIE property with a maximum absorption in the visible light range, red fluorescence emission, and a large Stokes shift. The colloidally stable TTCy-PNPs with a sub-100 nm particle size displayed a visible light absorption behavior similar to that of the TTCy molecules, facilitating the excitation of TTCy-PNPs with biologically benign white light to emit orange-red fluorescence. The TTCy-PNPs, as type I and type II photosensitizers, could generate both singlet oxygen and superoxide radicals. The dual-mode TTCy-PNPs exhibited low cytotoxicity, efficient cellular uptake, a bright fluorescence signal, and photodynamic killing under white light irradiation, demonstrating a promising application for fluorescence cell imaging and photodynamic theranostics. The molecular and structural design of PNPs with AIE and PDT functions as well as miniemulsion-based preparation may guide the design and efficient fabrication of nanotherapeutic platforms for versatile biological and medical applications.