Generally guided bone regeneration uses membranes to separate the wound from invading soft tissue cells in order to provide a proper place for bone cells to proliferate and function. Ideally a membrane should be biodegradable, own proper physical characteristics, porous and non toxic. Biodegradability of the membrane prevents from second surgery in order to be extracted. In our current research we chose collagen as our funding material to make a membrane. Collagen was dissolved in 5.0 molar acetic acid for 24 hours, freeze dried and then was crossed linked by NHS and EDC solutions using MES buffer. It was then washed and freeze dried again. In this experiment by performing Fourier transform infrared spectroscopy (FTIR) for crosslinked and non-crosslinked samples it was verified that the bonds in the crosslinked sample was much more strengthened in compare with the non-crosslinked one. Afterwards by performing mechanical test with Anton Paar rheometer and SEM analysis it was concluded that among 5, 10 and 20 mg/ml concentrations of collagen the latest revealed the best results in terms of physical properties and pore size. Collagen sample derived from 20 mg/ml concentration of collagen solution and crosslinked with the same mole ratio of crosslinker had the pore size with the range of 27 to 96 microns and it is comparable with commercial samples. As the effect of the crosslinker ratio on storage modulus had not been considered in previous projects, by applying the regarded tests it was also shown that a same ratio of EDC and NHS provides the highest storage modulus. The highest storage modulus was 4.58 Mpa and belonged to the collagen sample derived from 20 mg/ml concentration of collagen solution and crosslinked with the same mole ratio of crosslinker which showed 37% increase in compare with the same collagen concentration but with different crosslinker mole ratio (EDC:NHS=2:1). By comparing the SEM images of non-crosslinked sample as a control sample with other crosslinked samples it was concluded that crosslinking causes a much more regular morphology in collagen structure. Additionally, crosslinked samples show a wider range of pore sizes in compare with the non-crosslinked sample. Key Words membrane, collagen, crosslink, pore size.
