Upconverting nanoparticles for cellular imaging

Abstract

Fluorescent labels that are excited by the near infrared (NIR) radiation are advantageous because these give rise to minimal autofluorescence because of lack of efficient endogenous absorbers in the NIR spectral range [1-3], and results in very high signal to background ratios. Furthermore, photo-damage to cells and tissues is also greatly reduced because NIR is generally harmless to biomolecules in low doses. In this report we present the use of ultrafine, pure cubic silica coated NaYF4 nanocrystals co-doped with lanthanide ions ions Yb3+ and Er3+. To the best of our knowledge these represent the first report of the use of sub-40 nm upconversion nanoparticles in biomedical imaging.