Upconverting
nanoparticles (UCNPs) doped with Yb3+ and
Tm3+ are near-infrared (NIR) to ultraviolet (UV) transducers
that can be used for NIR-controlled drug delivery. However, due to
the low quantum yield of upconversion, high laser powers and long
irradiation times are required to trigger this drug release. In this
work, we report the one-step synthesis of a nanocomposite consisting
of a LiYbF4:Tm3+@LiYF4 UCNP coated
with mesoporous UV-breakable organosilica shells of various thicknesses.
We demonstrate that a thin shell accelerates the breakage of the shell
at 1 W/cm2 NIR light exposure, a laser power up to 9 times
lower than that of conventional systems. When the mesopores are loaded
with hydrophobic vitamin D3 precursor 7-dehydrocholesterol
(7-DH), shell breakage results in subsequent cargo release. Its minimal
toxicity in HeLa cells and successful internalization into the cell
cytoplasm demonstrate its biocompatibility and potential application
in biological systems. The tunability of this system due to its simple,
one-step synthesis process and its ability to operate at low laser
powers opens up avenues in UCNP-powered NIR-triggered drug delivery
toward a more scalable, flexible, and ultimately translational option.