Guiding cellular activity with polarized light

Engineering Hydrogel-Based Biomedical Photonics: Design, Fabrication, and Applications

Light guiding and manipulation in photonics have become ubiquitous in events ranging from everyday communications to complex robotics and nanomedicine. The speed and sensitivity of light-matter interactions offer unprecedented advantages in biomedical optics, data transmission, photomedicine, and detection of multi-scale phenomena. Recently, hydrogels have emerged as a promising candidate for interfacing photonics and bioengineering by combining their light-guiding properties with live tissue compatibility in optical, chemical, physiological, and mechanical dimensions. Herein, the latest progress over hydrogel photonics and its applications in guidance and manipulation of light is reviewed. Physics of guiding light through hydrogels and living tissues, and existing technical challenges in translating these tools into biomedical settings are discussed. A comprehensive and thorough overview of materials, fabrication protocols, and design architectures used in hydrogel photonics is provided. Finally, recent examples of applying structures such as hydrogel optical fibers, living photonic constructs, and their use as light-driven hydrogel robots, photomedicine tools, and organ-on-a-chip models are described. By providing a critical and selective evaluation of the field's status, this work sets a foundation for the next generation of hydrogel photonic research.

The I/T curve coefficient for evaluating changes in neuromuscular excitability after polarized light irradiation - a placebo-controlled randomized trial

Introduction: PILER light affects the sensory and motor excitability of the tissue, and these changes may depend on the color of the filter used in the irradiations. Objective: To evaluate changes in neuromuscular excitability after PILER irradiation with different filters. To evaluate the usefulness of the I/T curve coefficient in neuromuscular excitability test. Material and methods: 60 healthy volunteers assigned to four groups: group v - without filter (n=15), group x - red filter (n=15), group y - blue filter (n=15), group z - placebo (n=15) had biceps brachii irradiated with PILER light. Outcome Measures: I/T curve coefficient for rectangular (■I/T coeff) and triangular (▲I/T coeff) pulses for sensory and motor excitability and the pressure pain threshold (PPT). Results: ■I/T coeff (p=0.0013) and ▲I/T coeff (p=0.0011) for sensory excitability increased significantly in the irradiated group. ■I/T coeff (p=0.0356) and ▲I/T coeff (p=0.0022) increased significantly after blue light irradiation. A significant increase in the▲I/T coeff (p=0.0439) in motor excitability was observed in the irradiated group. ■I/T coeff (p=0.0309) and ▲I/T coeff (p=0.0064) increased significantly after blue light irradiation. Conclusion: PILER light may reduce muscle excitability. Using a blue filter may increase the sensory threshold, and myorelaxation. Further experiments are necessary to confirm the usefulness of the I/T curve coefficient.