Light-Guiding Biomaterials for Biomedical Applications

Optical techniques used in medical diagnosis, surgery, and therapy require efficient and flexible delivery of light from light sources to target tissues. While this need is currently fulfilled by glass and plastic optical fibers, recent emergence of biointegrated approaches, such as optogenetics and implanted devices, calls for novel waveguides with certain biophysical and biocompatible properties and desirable shapes beyond what the conventional optical fibers can offer. To this end, exploratory efforts have begun to harness various transparent biomaterials to develop waveguides that can serve existing applications better and enable new applications in future photomedicine. Here, the recent progress in this new area of research for developing biomaterial-based optical waveguides is reviewed. It begins with a survey of biological light-guiding structures found in plants and animals, a source of inspiration for biomaterial photonics engineering. The review then describes natural and synthetic polymers and hydrogels that offer appropriate optical properties, biocompatibility, biodegradability, and mechanical flexibility have been exploited for light-guiding applications. Finally, perspectives on biomedical applications that may benefit from the unique properties and functionalities of light-guiding biomaterials are discussed briefly.