Delivery of upconversion microparticles [Y2O3:Yb, Er] and quantum dots (CuInS2/ZnS coated with PEG-based amphiphilic polymer) into rat skin using the fractional laser microablation has been studied in vivo. Luminescence spectroscopy, optical coherence tomography, confocal microscopy, and histochemical analysis were used for visualization of nanoparticles in microchannels. Results have shown that the upconversion microparticles are detected more efficiently in comparison with the quantum dots. The fluorescence intensity of the inserted upconversion microparticles is higher, when the Omnipaque™ was applied as a skin optical clearing agent. The fluorescent images of upconversion nanoparticle distribution indicate the advantage of particle delivery into skin by ultrasound.
Optical clearing of the rat skin under the action of propylene glycol was studied exvivo. It was found that collimated transmittance of skin samples increased, whereas weight and thickness of the samples decreased during propylene glycol penetration in skin tissue. A mechanism of the optical clearing under the action of propylene glycol is discussed. Diffusion coefficient of propylene glycol in skin tissue exvivo has been estimated as (1.35±0.95)×10-7 cm2/s with the taking into account of kinetics of both weight and thickness of skin samples. The presented results can be useful for enhancement of many methods of laser therapy and optical diagnostics of skin diseases and localization of subcutaneous neoplasms.