Triethyleneglycol dimethacrylate addition improves the 3D-printability and construct properties of a GelMA-nHA composite system towards tissue engineering applications

In tissue engineering, there is a growing interest in the development of 3D printable bone tissue-inspired nanocomposites. However, most such nanocomposites have poor mechanical properties, owing to poor dispersion of the mineral phase (e.g. nano-hydroxyapatite, nHA) within the organic phase (e.g. methacrylated gelatin, GelMA) and low volume fractions of each phase. Triethyleneglycol dimethacrylate (TEGDMA) is commonly added to dental resin-based composites to improve the properties of the dental resin. Here, the effects of substituting a portion of the water phase in a GelMA-nHA composite with TEGDMA were evaluated. TEGDMA improved the dispersion of nHA within the highly-concentrated GelMA-based composite ink, as well as increased the ink's shear yield strength and reduced the critical energy for ink cure. As a result, the printability of the composite ink was greatly improved upon TEGDMA inclusion. Lastly, while the swelling of the cast composite in 37 °C water increased slightly, the mechanical properties (tensile strength, toughness, and stiffness) of the cast composite increased by at least an order of magnitude upon TEGDMA addition, and all composites demonstrated MSC cytocompatibility after 24 h. Overall, TEGDMA shows promise as an additive to tune properties of the GelMA-nHA system towards use in tissue engineering applications.

Structural analysis of xSrO-(50 - x)CaO-50P2O5 glasses with x=0, 5, or 10 mol% for potential use in a local delivery system for osteomyelitis treatment

The introduction of ions into a local delivery matrix is one method of managing degradation and subsequent release of the incorporated therapeutic agents. Of interest in this study was whether we could modify the structural nature of calcium polyphosphate (CPP) glass and the subsequent therapeutic potential of this local delivery matrix with inclusion of strontium (Sr). We found that adding 10 mol% Sr significantly increased the density and chain length of the glass. There was no significant impact of Sr doping on the subsequent loading of vancomycin into the matrix, or the matrix porosity. The noted differences in structural stability, ion release, and vancomycin release between the un-doped CPP matrices and 10 mol% Sr-doped CPP matrices in vitro are likely a result of a decrease in glass disorder upon Sr addition to the glass and preferential retention of Sr over Ca during matrix degradation. This study has provided further evidence that Sr incorporation may serve to both manipulate antibiotic release from the amorphous CPP matrix and provide a potential source of therapeutic ions for enhanced bone regeneration.