Synthesis, Characterization and 3D Micro-Structuring via 2-Photon Polymerization of Poly(glycerol sebacate)-Methacrylate–An Elastomeric Degradable Polymer

Abstract

Poly(glycerol sebacate) (PGS) has been utilized in numerous biomaterial applications over recent years. This elastomeric and rapidly degradable polymer is cytocompatible and suited to various applications in soft tissue engineering and drug delivery. Although PGS is simple to synthesize as an insoluble prepolymer, it requires the application of high temperatures for extended periods of time to produce an insoluble matrix. This places limitations on the processing capabilities of PGS and its possible applications. Here, we present a photocurable form of PGS with improved processing capabilities: PGS-methacrylate (PGS-M). By methacrylating the secondary hydroxyl groups of the glycerol units in the PGS prepolymer chains, the material was rendered photocurable and, in combination with a photoinitiator, crosslinked rapidly on exposure to UV light at ambient temperatures. The polymer's molecular weight and the degree of methacrylation could be controlled independently and the mechanical properties of the crosslinked material tailored. The polymer also displayed rapid degradation under physiological conditions and cytocompatibility with various primary cell types. As a demonstration of the processing capabilities of PGS-M, µm scale 3D scaffold structures were fabricated using 2-photon polymerization and used for 3D cell culture. The tunable properties of PGS-M coupled with its enhanced processing capabilities make the polymer an attractive potential biomaterial for various future applications.

Characterizing Cross‐Linking Within Polymeric Biomaterials in the SEM by Secondary Electron Hyperspectral Imaging

“…[20] The weaker bonding energies of double bonds and acrylate groups are a common starting point for radical reactions like polymerization or cross-linking processes. [15] The SE spectra captured from the surfaces of PGS-M for the three specimens with different cross-linking densities are displayed in Figure 2B. The most prominent differences observed between PGS-M 30%, 50%, and 80% DM were in the spectral range around 2950 cm −1 .…”

“…PGS being a non-toxic tuneable polymer, [8,9] has become an interesting potential biomaterial in various promising applications such as supporting the growth of cardiac tissue, [10] blood vessels, [11,12] and cartilage. [15] The ease with which PGS-M can be synthesized together with the adaptability of its physical properties and suitability for use with different cell types, makes PGS-M an attractive candidate for an extensively deployed biomaterial. The photocurable capability of PGS-M enhances the existing strengths of PGS by allowing the material to be cross-linked at lower temperatures and pressures.…”

“…[13,14] PGS-M differs from PGS as a result of functionalization with methacrylate groups which causes the polymer to be photocurable. [15] The adaptability relies on user-defined cross-linking as PGS-M can be photocured at various degrees of methacrylation and the degree of methacrylate (DM) used in its production has a direct relationship to the density of cross-linking. This enables the precise fabrication of highly detailed microscale structures and the potential direct incorporation of cells or temperature sensitive molecules.…”

“…The photocurable capability of PGS-M enhances the existing strengths of PGS by allowing the material to be cross-linked at lower temperatures and pressures. [15,16] Further validation is required to confirm this relationship but PGS-M is generating much interest as a biomaterial. [15] The ease with which PGS-M can be synthesized together with the adaptability of its physical properties and suitability for use with different cell types, makes PGS-M an attractive candidate for an extensively deployed biomaterial.…”

“…Tensile testing has previously revealed that the mechanical properties of PGS-M varied in accordance with its morphology, both Young's modulus and UTS increased significantly with increasing levels of DM. [15,16] Further validation is required to confirm this relationship but PGS-M is generating much interest as a biomaterial. PGS-M is therefore considered an ideal model polymer to assess SEHI as a viable biomaterial cross-linking characterization technique.…”