Tryptophan intrinsic fluorescence from wound healing correlates with re-epithelialization in a rabbit model.

BACKGROUND: Wound healing monitoring and timely decision-making are critical for wound classification. Tryptophan (Tr) intrinsic fluorescence, detected at 295/340 nm, provides a noninvasive approach for wound assessment. Our previous work demonstrated that this autofluorescence is associated with keratinocytes in a highly proliferative state in vitro. OBJECTIVE: We investigated the correlation between Tr fluorescence and key wound healing parameters, including re-epithelialization, fibrosis, neovascularization, and acute and chronic inflammation, using a rabbit model. METHODS: Seven rabbits underwent wound healing assessment over a 15-day period. We employed histological analysis from central and marginal biopsies, and UV fluorescence imaging captured by a monochromatic near-UV sensitive camera equipped with a passband optical filter (340 nm/12 nm). Excitation was achieved using a 295 nm LEDs ring lamp. Normalized fluorescence values were correlated with histological measurements using Pearson correlation. RESULTS: The UV fluorescence strongly exhibited a strong correlation with re-epithelization (r = 0.8) at the wound edge, with peak intensity observed between the sixth and ninth days. Notably, wound-healing dynamics differed between the wound center and edge, primarily attributed to variations in re-epithelialization, neovascularization, and chronic inflammation. CONCLUSION: Our findings highlight the presence of autofluorescence at 295/340 nm during wound healing, demonstrating a robust association with re-epithelialization. This excitation/emission signal holds promise as a valuable noninvasive strategy for monitoring wound closure, re-epithelialization, and other biological processes where Tr plays a pivotal role.

All-fiber few-mode interference for complex azimuthal pattern generation.

We report on an all-fiber setup capable of generating complex intensity patterns using interference of few guided modes. Comprised by a few-mode fiber (FMF) spliced to a multimodal interference (MMI) fiber device, the setup allows for obtaining different output patterns upon adjusting the phases and intensities of the modes propagating in the FMF. We analyze the output patterns obtained when exciting two family modes in the MMI device using different phase and intensity conditions for the FMF modal base. Using this simple experimental arrangement we are able to produce complex intensity patterns with radial and azimuthal symmetry. Moreover, our results suggest that this approach provides a means to generate beams with orbital angular momentum (OAM).