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

Abstract

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.

Engineering Polysaccharide‐Based Hydrogel Photonic Constructs: From Multiscale Detection to the Biofabrication of Living Optical Fibers

“…The dense silica also hinders the diffusion of biological molecules [11] and presents optical mismatches when interfacing with biological tissues. [12] Hydrogels have been explored as more sustainable, degradable photonic alternatives with physiological-level mechanics [13] and better light coupling. [12] Hydrogel optical fibers have been fabricated with synthetic, UV-crosslinking materials such as poly(ethylene glycol) (PEG) [14][15][16][17][18][19] and acrylamide.…”

“…[12] Hydrogels have been explored as more sustainable, degradable photonic alternatives with physiological-level mechanics [13] and better light coupling. [12] Hydrogel optical fibers have been fabricated with synthetic, UV-crosslinking materials such as poly(ethylene glycol) (PEG) [14][15][16][17][18][19] and acrylamide. [20] These fibers were shown capable of integrating tissues, [14,18] stimulating cells, [14,19] and sensing varied phenomena.…”

“…Although existing materials employed so far excel in hydrogel light-guiding, the characteristic of hydrogels, namely the high mesh density and cytotoxic, UV-based crosslinking, also prevent the integration of living entities in the light-guiding core compartment. [12] Herein, we address these limitations by presenting multilayered hydrogel optical fibers based solely on ionic-crosslinking,…”

“…Although existing materials employed so far excel in hydrogel light‐guiding, the characteristic of hydrogels, namely the high mesh density and cytotoxic, UV‐based crosslinking, also prevent the integration of living entities in the light‐guiding core compartment. [ 12 ]…”

General One-Pot Method for Preparing Highly Water-Soluble and Biocompatible Photoinitiators for Digital Light Processing-Based 3D Printing of Hydrogels

“…Hydrogels, polymer/supramolecular networks containing a large amount of water, have gained great attention due to their great biocompatibility and processibility. − Since hydrogels are highly designable and manufacturable, they can be fabricated to various structures or devices that have been employed to a plenty of applications including drug packaging and delivery, − human-like tissues (artificial axons, cartilage-like, artificial skin, etc. ), − flexible electronic devices (actuators, motion sensors, miniature capacitors, etc.…”