The introduction of new upconverting nanoparticles (UPCNPs) in the tumor
area is being investigated worldwide as a solution for deep tissue
theranostics interventions. Moreover, as the development of biophotonics
techniques permits bioimaging in nanoscale, both photodynamic and
photothermal sensing should be achieved even at cellular level with
minimum perturbation, i.e., in absence of any physical contact between
cells and sensing units at a single-cell level via optical tweezers. In
our work, we discuss the biophotonic upconversion mechanism of
nanoparticles' excitation/emission at cellular level, under laser
trapping conditions, via considering laser radiation of NIR
(specifically at lambda = 808 nm) for optimal penetration in biological
tissues. Moreover, a theoretical simulation model will be presented for
evaluation of the electric field distribution in optically trapped
particles. Water soluble UPCNPs with maximum absorbance wavelength at
lambda = 808 nm and emission at 545 nm and 660 nm will be studied. The
photoluminescence of biocompatible UPCNPs could provide a promising
powerful tool for PDT single-cell analysis and/or for photothermal
enhancement and sensing in an optical tweezers' platform
