Delivery and reveal of localization of upconversion luminescent microparticles and quantum dots in the skin in vivo by fractional laser microablation, multimodal imaging, and optical clearing

Delivery and spatial localization of upconversion luminescent microparticles [Y 2 O 3 ;Yb, Er] (mean size ~1.6 μm) and quantum dots (QDs) (CuInS 2 ZnS nanoparticles coated with polyethylene glycol-based amphiphilic polymer, mean size ~20 nm) inside rat skin was studied in vivo using a multimodal optical imaging approach. The particles were embedded into the skin dermis to the depth from 300 to 500 μm through microchannels performed by fractional laser microablation. Low-frequency ultrasound was applied to enhance penetration of the particles into the skin. Visualization of the particles was revealed using a combination of luminescent spectroscopy, optical coherence tomography, confocal microscopy, and histochemical analysis. Optical clearing was used to enhance the image contrast of the luminescent signal from the particles. It was demonstrated that the penetration depth of particles depends on their size, resulting in a different detection time interval (days) of the luminescent signal from microparticles and QDs inside the rat skin in vivo. We show that luminescent signal from the upconversion microparticles and QDs was detected after the particle delivery into the rat skin in vivo during eighth and fourth days, respectively. We hypothesize that the upconversion microparticles have created a long-time depot localized in the laser-created channels, as the QDs spread over the surrounding tissues

Ultrasound stimulated release and catalysis using polyelectrolyte multilayer capsules

Ultrasound has been used to trigger release of encapsulated material from polyelectrolyte multilayer capsules. Sonication was found to destroy both plain and nanoparticle-modified capsules. Cavitation occurs through the collapse of generated microbubbles and the resulting shear forces should cause the destruction of the polyelectrolyte capsules. Application in catalysis is demonstrated in this paper, while further potential usage of ultrasound triggered release is anticipated in bio-medical applications

Permeability adjustment of polyelectrolyte micro-and nanocapsules by laser irradiation

Laser radiation was used for permeability increase up to destroy of polyelectrolyte capsules. Silver and gold nanoparticles was synthesized and incorporated into capsule shells to attain the sensitivity of microcapsules to laser radiation. Lasers of different power and wavelength were used. The sensitivity of nanocomposite shell to laser radiation can be controlled by nanoparticle shape, content and distribution into the shell