A new photo-processable hybrid copolymer based on gelatin-poly(trimethylene carbonate) (Gel-g-PTMCn) was elaborated and showed a promising potential as resin for stereolithography towards the fabrication of scaffold for tissue engineering. Various lengths of PTMC were grafted from gelatin using hydroxy and amino side groups of the constitutive amino acids. The characterization of resulting hybrid copolymers was fully investigated by quantitative NMR spectroscopy before rendering them photosensitive by methacrylation of the PTMC terminal groups (Gel-g-PTMCn-MA). Homogeneous composition of the photo-crosslinked hybrid polymers was demonstrated by EDX spectroscopy and electronic microscopy. By performing subsequently water absorption,contact angle measurements, and degradation study we also showed the contribution of PTMC amount on the hybrid polymer behavior. The photo-crosslinked materials immersed in water were examined by using tensile experiments and displayed a large panel of materials from hydrogel to elastomer-like. Moreover, the absence of cytotoxicity conducted following the ISO10993 assay, validated the potential of such hybrid polymers in tissue engineering. As proof-of-concept 3D porous objects were successfully fabricated using stereolithography showing the great potential of those hybrid copolymers to be used as scaffolds for tissue engineering and regenerative medicine.
Highlights-A new device was validated to mechanically stimulate and characterize microspheres.-Six microspheres (size 900-1500µm) can be stimulated with various pressure signals.-Biomaterials of various mechanical properties can be stimulated and characterized.
Articular cartilage (AC) is the thin tissue that covers the long bone ends in the joints and that ensures the transmission of forces between adjacent bones while allowing nearly frictionless movements between them. AC repair is a technologic and scientific challenge that has been addressed with numerous approaches. A major deadlock is the capacity to take in account its complex mechanical properties in repair strategies. In this review, we first describe the major mechanical behaviors of AC for the non‐specialists. Then, we show how researchers have progressively identified specific mechanical parameters using mathematical models. There are still gaps in our understanding of some of the observations concerning AC biomechanical properties, particularly the differences in extracellular matrix stiffness measured at the microscale and at the millimetric scale. Nevertheless, for bioengineering applications, AC repair strategies must take into account what are commonly considered the main mechanical features of cartilage: its ability to withstand high stresses through three main behaviors (elasticity, poroelasticity and swelling). Finally, we emphasize that future studies need to investigate AC mechanical properties at different scales, particularly the gradient of mechanical properties around cells and across the cartilage depth, and the differences in mechanical properties at different scales. This multi‐scale approach could greatly enhance the success of AC restorative approaches.
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