Collagen is widely used in tissue engineering as a scaffold for cell replication and differentiation. Detecting collagen microstructure formed under different ion conditions can help to optimize its application in tissue engineering. In this study, we employed phosphate, sulfate and chloride to study the microstructure these ions induce during the assembly of collagen hydrogels. When phosphate concentration was 5 to 20 mM, 2 g/L collagen samples incubated under 37 �C did not form hydrogels. The protein precipitated into �chunks� and collagen solubility was about 0.12 g/L. When phosphate concentration was 20 to 100 mM, the collagen samples formed hydrogels.  Collagen solubility as well as multiphoton microscopy detected collagen fiber lengths increased. When phosphate concentration was 100 to 160 mM, collagen fiber length decreased along with collagen solubility. Collagen solubility was at the maximum value (0.305 g/L) when phosphate concentration was 100 mM and fibers' length was maximum (46.5 �m) in about 120 mM phosphate. Polymerization kinetics followed by monitoring changes in turbidity confirmed that phosphate inhibited collagen self-assembly process. Sulfate showed similar results. For NaCl experiment, we separately prepared hydrogels at room temperature, 27 �C and 37 �C while varying ionic strength of phosphate buffer with 0 to 0.9 M NaCl. Self-assembly depended greatly on the polymerization temperature and collagen solid content. When temperature was room temperature and 27 �C, turbidity measurements showed no obvious effect when NaCl was between 0.15 and 0.6 M. Multiphoton microscopy detected long, well connected collagen fibers. Short lag time and fast assembly rates were observed when NaCl was 0 or 0.9 M. Short, connected fibers were detected under 0 M NaCl. In 0.9 M NaCl, only unconnected one micron fiber nuclei with very low second harmonic generation contrast had formed. When temperature was 37 �C, all samples assembled fast and had small fibers.

Detecting the effect of ions on the microstructure formation of collagen hydrogel

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.