Structure-function characteristics of the biomaterials based on milk-derived proteins

There is an impetus on development of implantable biomaterials with the characteristics of improved biodegradability, bio-absorbability and wound healing activities. The milk proteins have valuable nutritional and biological properties, which lead to the promotion of quality health. In this study, whey protein isolate or WPI (highly aggregated) and its component lactalbumin (less aggregated) were melt blended with polycaprolactone (PCL) and then compression moulded into thin sheets (∼1 mm thickness). The effects of structural morphologies of the proteins on the mechanical, morphological, in vitro enzymatic degradation, and cytotoxicity and cell proliferation characteristics of the biomaterials were examined. In general, the tensile strength and modulus of the biomaterials decreased with increasing protein content. Compared to WPI, lactalbumin showed a better compatibility with the PCL matrix as observed in the mechanical properties and scanning electron microscopic morphology. The biomaterials exhibited a good retention of the mechanical characteristics after digestion in a physiologically simulated fluid containing trypsin enzyme. However, lactalbumin containing biomaterials showed a better retention of the tensile properties compared to WPI containing biomaterials. The cell culture studies indicated that the biomaterials have no cytotoxic effects, moreover they enhanced the proliferation of L929 cells compared to the pure PCL. Finally, this study indicated that the PCL based biomaterials with a protein content of 20 wt% may be applied in fabrication of implantable devices for soft tissue engineering, where it requires a reasonably low to moderate mechanical strength (e.g., ∼10 MPa tensile strength), and improved biodegradability, biocompatibility and tissue healing activities.