International Session 16　　Immunology

Purpose: Limited penetration depth of light in biological tissues is a key challenge in light-based therapies, such as photothermal therapy and photodynamic therapy.Methods: This study demonstrates a biocompatible, implantable device for deep tissue light delivery.The prototype is fabricated using polyethylene glycol diacrylate polymers, combining planar waveguides with lens-microneedle.The optical beam pass through the microneedles to optimize light intensity in the tissue.Result and Discussion: The hydrogel waveguide with five lens-microneedles extends treatment depth to 24 mm and treatment area to 3 1 cm .Photoswitchable chemotherapy against colorectal cancer cells is activated using various hydrogel waveguides.Hydrogel-waveguide enabled photoswitching is evaluated through optical microscopy, crystal violet staining, and MTT assays.The anticancer drug activated by the hydrogel device is twice as effective in inducing cancer cell death compared to other waveguides.Conclusions: The biodegradable waveguide offers optimal light delivery and does not require removal, as it is resorbed by tissue.This approach holds potential for widespread use in photomedicine.