Upconversion nanoparticles: synthesis, surface modification and biological applications

Rare earth doped upconversion nanoparticles, which can convert long wavelength near infrared radiation into short wavelength visible radiation via a non-linear optical process, are emerging as a new class of fluorescent biolables. They can overcome some of the limitations of conventional biolables including organic dyes and quantum dots. This review highlights recent advances in the synthesis, surface modification, and biological applications of rare earth doped upconversion nanoparticles.363