Natural product-based functional polymers meet the growing demand for biomaterials. Bile acids are attractive building blocks due to their rigid steroidal skeleton, biocompatibility, and metabolic degradability. However, conventional polymerization methods typically require cumbersome premodification procedures. In this study, an efficient hydroxyl-yne/carboxyl-yne click polymerization strategy was employed to directly polymerize natural bile acids with activated alkynes, catalyzed by 1,4-diazabicyclo2.2.2octane (DABCO) under mild conditions. The process required only 6 h, efficiently producing a series of poly(bile acid)s with high molecular weight (up to 37,000) and near-quantitative yields, which demonstrates excellent atom economy. The resulting polymers exhibited good solubility and thermal stability, and demonstrated significant alkaline degradation properties due to the presence of multiple ester and vinyl ether bonds in the backbone. More interestingly, the dense ester groups induce unique clusteroluminescence via a through-space conjugation effect. The luminescent properties of these polymers have been explored successfully for use in specific fluorescent imaging of lysosomes in living cells. This direct valorization of natural biocompounds yields new functional polymeric materials that combine degradability, clusteroluminescence, and biocompatibility.
Shen et al. (Tue,) studied this question.