Luminescent silicon nanoparticles for distinctive tracking of cellular targeting and trafficking
Developing therapeutic nanoparticles that actively target disease cells or tissues by exploiting the binding specificity of receptors presented on the cell surface have extensively opened up biomedical applications for drug delivery and imaging. An ideal nanoparticle for biomedical applications is required to report confirmation of relevant targeting and the ultimate fate in physiological environment for further verification, e.g. to adapt dosing or predict response. Herein, we demonstrate tracking of silicon nanoparticles through intrinsic photoluminescence (PL) during the course of cellular targeting and uptake. Time-resolved analysis of PL characteristics under cellular microenvironment provides dynamic information of physiological condition where the silicon nanoparticles exposed. In particular, the PL lifetime of the silicon nanoparticles is on the order of microseconds, significantly longer than the nanosecond lifetimes exhibited by fluorescent molecules naturally presented in cells, thus allows discrimination of the nanoparticles from the cellular background autofluorescence in time-gated imaging. The PL lifetime is a physically intensive property that reports the inherent characteristics of the nanoparticles regardless of surrounding noise. Furthermore, we investigate a unique means to inform the lifespan of the biodegradable silicon nanoparticles responsive to local microenvironment in the course of endocytosis. Multivalent strategy of nanoparticles for enhanced cell targeting is also demonstrated with complementary analysis of time-resolved PL emission imaging and fluorescence correlation spectroscopy. The result presents a promising potential of the photoluminescent silicon nanoparticles toward advanced cell targeting systems that simultaneously enable tracking the cellular trafficking and the tissue microenvironment monitoring.
- This article is part of the themed collection: Luminescent silicon nanostructures