Assessing toxicity of Upconversion nanoparticles

Upconversion (UCNPs) is a non-linear anti-Stokes technique for transforming two or more low-energy stimulation photons most often NIR light into some kind of higher-energy photon (e.g. NIR visible ultraviolet). It utilizes the long-life time and real ladder-like energy levels of trivalent lanthanide ions doped with inorganic host particle. Of these inorganic host particles Chlorophyll types differ from other photosensitizers (PSs) in a number of ways. Furthermore the wavelength acceptable for chlorophyll kinds was longer than the wavelength suited for hematoporphyrin types. Because UCNPs are employed in biological methods their potential toxicity and biocompatibility must be assessed. UCNPs cannot be quickly incorporated into biological systems.