Porous organosilica nanoparticles enable UV blocking and two-photon fluorescence imaging

Porous organosilica nanoparticles (PONs) are promising hybrid materials for a wide range of advanced applications, particularly in biomedical imaging, therapeutic delivery systems, and UV protection, due to their tunable organic-inorganic frameworks. However, integrating specific organic groups within PONs' structure, bearing function-enabling characteristics, remains challenging. Here we report the synthesis of novel PONs incorporating organic groups with UV-blocking and intrinsic anti-Stokes fluorescence capabilities, suitable for deep tissue imaging. The novel materials are prepared via co-condensation of a UV-absorbing triazine-based organosilane precursor with biphenyl-bridged silanes, yielding nanoparticles exhibiting broad UV protection (SPF ∼26) and strong anti-Stokes fluorescence upon continuous wave and femtosecond laser excitation above 700 nm. Spectroscopic analysis revealed distinct excitation mechanisms: hot-band absorption under continuous wave and two-photon excitation fluorescence (TPEF) under pulsed irradiation. The nanoparticles demonstrated high biocompatibility toward human skin cells and enabled effective two-photon imaging of glioblastoma cells, showing time-dependent cellular uptake. These multifunctional PONs combine UV shielding and advanced imaging capabilities, offering potential for applications in skin protection and nanomedicine, particularly for simultaneous imaging and therapeutic delivery.