Biodegradable polymers have significant potential in biotechnology and bioengineering. However, for some applications, they are limited by their inferior mechanical properties and unsatisfactory compatibility with cells and tissues. A strong, biodegradable, and biocompatible elastomer could be useful for fields such as tissue engineering, drug delivery, and in vivo sensing. We designed, synthesized, and characterized a tough biodegradable elastomer from biocompatible monomers. This elastomer forms a covalently crosslinked, three-dimensional network of random coils with hydroxyl groups attached to its backbone. Both crosslinking and the hydrogen-bonding interactions between the hydroxyl groups likely contribute to the unique properties of the elastomer. In vitro and in vivo studies show that the polymer has good biocompatibility. Polymer implants under animal skin are absorbed completely within 60 days with restoration of the implantation sites to their normal architecture.

Host remodeling is important for the success of medical implants including vascular substitutes. Synthetic and tissue-engineered grafts have yet to show clinical effectiveness in arteries smaller than 5 mm. We designed cell-free biodegradable elastomeric grafts that degrade rapidly to yield neo-arteries nearly free of foreign materials 3 months after interposition grafting in rat abdominal aorta. This design focuses on enabling rapid host remodeling. Three months post-implantation, the neo-arteries resemble native arteries in the following aspects: regular, strong and synchronous pulsation, a confluent endothelium and contractile smooth muscle layers, co-expression of elastin, collagen and glycosaminoglycan, and tough and compliant mechanical properties. Therefore, future study employing large animal models more representative of human vascular regeneration is warranted before clinical translation. This cell-free approach represents a philosophical shift from the prevailing focus on cells in vascular tissue engineering, and may impact regenerative medicine in general.

No abstract

Biomimetic functional models of the mononuclear copper enzyme galactose oxidase are presented that catalytically oxidize benzylic and allylic alcohols to aldehydes with O2 under mild conditions. The mechanistic fidelity between the models and the natural system is pronounced. Modest structural mimicry proves sufficient to transfer an unusual ligand-based radical mechanism, previously unprecedented outside the protein matrix, to a simple chemical system.