Ablative fractional laser (AFL) treatment prior to application of a topical drug enhances drug uptake and the resultant coagulation zone (CZ) surrounding each fractional photothermal injury may provide a reservoir for sustained drug release. In this work, we evaluate how morphological changes in the skin after AFL affect the uptake of an intrinsically fluorescent topical antibiotic. Brightfield images of NBTC stained histopathological slides were evaluated using a deep learning approach for semantic segmentation of fractional laser patterns for automatic assessment of laser hole diameter and CZ morphology. Last, collagen denaturation and drug uptake were quantified via polarization and fluorescence microscopy, respectively.
Non-fractional lasers used for hair removal penetrate deep into the tissue (~4 mm), and can be repurposed for enhanced thermal delivery using topically applied indocyanine green (ICG), a highly absorptive NIR dye. We demonstrate a new methodology for achieving fractional damage with an 808nm diode laser using a microneedle array injector and ICG impregnated PLGA nanoparticle formulation. A comparison of the effects of injection depth and irradiation dose between free ICG and PLGA@ICG revealed that the nanoparticle formulation effectively concentrates and confines the fluorophore locally at depths of ~3mm and thermal damage is achieved with irradiances as low as 10J/cm2. These improvements in the delivery of ICG subcutaneously in a fractional pattern allow for confined dermal tissue injury using low irradiances, minimizing discoloration of superficial layers of the skin, and significantly enhancing the depth of thermal injury achievable with a wide-area non-fractional laser diode.
Intrinsic and extrinsic aging of human skin induces significant morphological changes to its surface. The most prominent and important feature in cosmetics and dermatology is the alteration of the wrinkles. Roughness parameters (Ra, Rmax) described by DIN/ISO disregard the skin’s micro-structure. Hence, we introduce an alternative method of skin roughness evaluation by analyzing the size and shape of micro-structures using optical coherence tomography. Measurements of young and elderly subjects were acquired. The skin of elderly subjects showed a decrease in micro-structures compared to the skin of young subjects which was predominated by triangular shapes, whereas rhomboids prevail among the elderly.
There is an unmet need for simple-to-use oximetry devices that can map tissue oxygenation over large areas while being easily integrated into clinical standard-of-care workflows. We present a phosphorescence-based approach which features red-emitting porphyrin molecule constructs, embedded within a paint-on hydrogel bandage for tissue oxygen concentration imaging. The bandage emission is visible by eye which enables oxygen imaging even in the presence of skin autofluorescence. Preclinical testing to validate correlations between bandage oxygenation maps and perfusion is ongoing, and by allowing gelation to occur on the skin the bandage can conform to odd topologies, such as ears.
Optical coherence tomography angiography (OCTA) provides in-vivo images of microvasculature. In skin it often represents a dynamic perfusion state without depicting the actual extent of the vascular network. Here, we present the capillary refill method for obtaining a more accurate anatomic representation of surface capillary networks in human skin using OCTA.
OCTA images were captured at baseline displaying ambient capillary perfusion and after compression and release of the skin representing the network of existing capillaries at full capacity. This method provides mapping of cutaneous capillary networks independent of ambient perfusion comparable to histological analysis of biopsies on identical skin sites.
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