Biodegradable hyperbranched polyesters of trimethylolpropane with acrylate side chains enabling sustainable gel materials and nanomaterials for drug delivery applications.

To date, various biodegradable polymers have been synthesized due to the merits of biodegradable polymers in biomedical applications. The current widely used biodegradable polymers generally have linear structures, such as poly(lactic--glycolic acid) (PLGA), which prevents polymer crosslinking and polymer modification covalent conjugation, thus restricting their even broader applications. In this research, we report the synthesis and studies of new sustainable polymers consisting of biodegradable backbones and side chains, which endow the polymers with complete biodegradability, biocompatibility, crosslinking, and availability for covalent chemical modifications. The convenient synthesis of the polymers needs no catalyst under ambient conditions, which effectively avoids the unintended toxicity and immune response associated with the catalyst residues in the polymer materials. Therefore, these polymers are especially desired in biomedical materials and devices. Moreover, the polymers can be fabricated into gel materials and nanomaterials. Using a near-IR fluorescent probe as an indicative cargo, we have established a biodegradable and biocompatible agent-delivering nanosystem paradigm with an average nanoscale size of ∼50 nm. In the nanoarchitectures, the cargo molecules are tethered to the nanoparticulate scaffold through covalent conjugation, preventing unwanted premature release of the cargo molecules in the blood circulation and thus circumventing the related systemic toxicity and adverse effects. Further, the delivery nanosystems are available for facile decoration with targeting ligands to attain disease-targeted delivery. The new materials exhibited excellent biocompatibility, signifying the immense potential they hold for biomedical applications.