High value biomaterials from dairy milk proteins

Abstract

Event Abstract Back to Event High value biomaterials from dairy milk proteins Azam Ali1, George J. Dias2 and Shahriar M. Hossain3* 1 University of Otago, Bioengineering Research Team, Department of Applied Sciences, New Zealand 2 University of Otago, Department of Anatomy, New Zealand 3 University of Wollongong, Institute for Superconducting and Electronic Materials,, Australia Introduction: There is a growing interest on development of high value biomaterials or medical devices using biologically derived compounds such as dairy milk proteins (DMPs). A large number of research reports are available on the development of films, foams and biocomposites from DMPs in conjunction of natural or biodegradable polymers for food and packing applications[1]-[3]; in contrast relatively fewer reports on the development of biomaterials/medical devices from DMPs can be found. Furthermore, when compared to other proteins e.g. collagen, silk, gelatin in the development of biomaterials/medical devices[4], DMPs again falls short. Protein-based biomaterials have the characteristics of improved bioabsorbability, biocompatibility, tissue healing/repairing, and regenerative activities[4],[5]. We are working on utilising DMPs (e.g. casein and whey) in the development of high value biomaterials for biomedical applications. Our initial findings have revealed the mechanical properties of DMPs can be altered to fit well with these applications. In this particular study, we investigate the processes to reconstitute casein protein into novel biomaterials, for soft tissue healing/repair. Materials and Methods: Casein protein (CP) and polycaprolactone (PCL) were used as received in powder form. PCL was blended with CP at 10 wt%, 20wt%, 30wt% and 50wt% concentrations, prior to melt-extrusion at 100°C and 80 rpm using a mini-laboratory melt-extruder. Melt-extruded sample was then compress-molded into 100 mm x 100 mm x 1 mm sheets at 100°C, by 5MPa press force for 5 min. Tensile strength (TS) and modulus of sheet samples (dry and in-vitro) were assessed using Instron tester. Scanning electron microscope (SEM) was used for assessing the structural morphology and degradation; in vitro methods for the assessment of biocompatibility, cytotoxicity and cell proliferation properties of these samples. Results and Discussion: Blending, melt-extrusion and compression molding techniques were found to be effective in the fabrication of protein-biomaterials with a CP content of up to 30 wt% without major processing issues. However, CP content of 50 wt% created major processing difficulties in the preparation of homogenous sheets, which were difficult to evaluate. At dry state TS of sheets consisting CP concentrations: 10wt%, 33-42 MPa; 20wt%, 15-20 MPa; and 30 wt%, 8-11 MPa; and their modulus,10 wt%, 146-153 MPa; 20 wt%, 112-120 MPa; and 30wt%, 85-90 MPa. TS and modulus showed an average of 10-20% decreases in vitro (in PBS containing trypsin at 35.4°C for 7 days). SEM study exhibited higher micelles structure at 50 wt% CP compared to 30 wt% or 20wt%, which revealed the presence of CP in the protein-biomaterial matrix. The cell culture (mouse fibroblast L929 cells) studies showed non-toxicity up to CP concentration of 30 wt%. The L929 cell viability was higher at 20 wt% CP compared to 30 wt% CP at 48 hr., which suggest that introducing CP having positive effect on cell adhesion and proliferation. Conclusion: This study demonstrated that casein protein can be used at desirable concentration to produce high value biomaterials with tailored/improved characteristics of structural, mechanical, which are biocompatible and biodegradable with potential for soft-tissue engineering applications. This research was funded by the University of Otago (UoO) and AgResearch Ltd collaborative Resaerch program