Design strategies for fluorescent biodegradable polymeric biomaterials

The combination of biodegradable polymer and fluorescent imaging has resulted in an important area of polymeric biomaterials: biodegradable fluorescent polymers. Researchers have made significant efforts in developing versatile fluorescent biomaterials due to their promising applications in biological/biomedical labeling, tracking, monitoring, imaging, and diagnostics, especially in drug delivery, tissue engineering, and cancer imaging. Biodegradable fluorescent polymers can function not only as implant biomaterials but also as imaging probes. Currently, there are two major classes of biodegradable polymers, which are used as fluorescent materials. The first class is the combination of non-fluorescent biodegradable polymers and fluorescent agents such as organic dyes and quantum dots. Another class of polymers shows intrinsic photoluminescence as polymers by themselves carrying integral fluorescent chemical structures in or pendent to their polymer backbone, such as Green Fluorescent protein (GFP), and the recently developed biodegradable photoluminescent polymer (BPLP). Thus there is no need to conjugate or encapsulate additional fluorescent materials for the latter. In the present review, we will review the fluorescent biodegradable polymers with emphases on material fluorescence mechanism, design criteria for fluorescence, and their cutting-edge applications in biomedical engineering. We expect that this review will provide an insightful discussion on the fluorescent biomaterial design and lead to innovations for the next generation of fluorescent biomaterials and fluorescence-based biomedical technology.