Elastomeric networks are increasingly being investigated for a variety of biomedical applications including drug delivery and tissue engineering. However, in some cases, their preparation requires the use of harsh processing conditions (e.g., high temperature), which limits their biomedical application. Herein, we demonstrate the ability to form elastomeric networks from poly(glycerol-co-sebacate) acrylate (PGSA) under mild conditions while preserving a wide range of physical properties. These networks presented a Young's modulus between 0.05 and 1.38 MPa, an ultimate strength from 0.05 to 0.50 Mpa, and elongation at break between 42% and 189% strain, by varying the degree of acrylation (DA) of PGSA. The in vitro enzymatic and hydrolytic degradation of the polymer networks was dependent on the DA. The copolymerization of poly(ethylene glycol) diacrylate with PGSA allowed for an additional control of mechanical properties and swelling ratios in an aqueous environment, as well as enzymatic and hydrolytic degradation. Photocured PGSA networks demonstrated in vitro biocompatibility as judged by sufficient human primary cell adherence and subsequent proliferation into a confluent monolayer. These photocurable degradable elastomers could have potential application for the encapsulation of temperature-sensitive factors and cells for tissue engineering.

Synthetic biodegradable polymers have made a considerable impact in various fields of biomedical engineering, such as drug delivery and tissue engineering. The design of synthetic biodegradable polymers for bioengineering purposes is challenging because of the application-specific constraints on the physical properties, including mechanical compliance and degradation rates, and the need for biocompatibility and low cytotoxicity.[1] The monomer selection frequently limits the range of required material properties. Our goal was to design a class of synthetic biopolymers based on a monomer that possesses a wide range of properties that are biologically relevant. This monomer ideally should be: (1) multifunctional to allow the formation of randomly crosslinked networks and a wide range of crosslinking densities; (2) nontoxic; (3) endogenous to the human metabolic system; (4) FDA approved; and (5) preferably inexpensive. We chose xylitol as it meets these criteria. We hypothesized that biodegradable polyesters could be obtained through copolymerization reactions with polycarboxylic acids; the hydration of such biodegradable polymers could be controlled by tuning the different compositions and stoichiometry of the reacting monomer. Here, we describe xylitol-based polymers that realize this design. Polycondensation of xylitol with watersoluble citric acid yielded biodegradable, water-soluble polymers. Acrylation of this polymer resulted in an elastomeric photocrosslinkable hydrogel. Polycondensation of xylitol with the water-insoluble sebacic acid monomer produced tough, biodegradable elastomers with tunable mechanical and degradation properties. These xylitol-based polymers exhibited excellent in vitro and in vivo biocompatibility compared to the well-characterized poly(L-lactic-co-glycolic acid) (PLGA), and are promising biomaterials. Sebacic acid (a metabolite in the oxidation of fatty acids) and citric acid (a metabolite in the Krebs cycle) were chosen as the reacting monomers for their proven biocompatibility; [2,3] they are also FDA-approved compounds. Polycondensation of xylitol with sebacic acid produced water-insoluble waxy prepolymers (termed PXS prepolymers). PXS prepolymers with a monomer ratio of xylitol: sebacic acid of 1:1 and 1:2 were synthesized and had a weight-average molecular weight (M w ) of 2443 g/mol (M n ¼ 1268 g/mol, polydispersity index (PDI) 1.9) and 6202 g/mol (M n ¼ 2255 g/mol, PDI 2.7), respectively. The PXS prepolymers were melted into the desired form and cured by polycondensation (120 8C, 40 m Torr for 4 days, 1 Torr ¼ 133.3 Pa) to yield low-modulus (PXS 1:1) and high-modulus (PXS 1:2) elastomers. PXS prepolymers are soluble in ethanol, dimethyl sulfoxide, tetrahydrofuran and acetone, which allows processing into more complex geometries. Polycondensation of xylitol with citric acid resulted in a water-soluble prepolymer (designated PXC prepolymer), of which the M w was 298 066 g/mol and the M n was 22 305 g/mol (PDI 13.4), compared to linear poly(ethylene glycol) (PEG) standards. To cro...

No abstract