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Aims: Age-Related Macular Degeneration (AMD) is one of the biggest causes of vision loss after 50 years of age in the world. AMD disease destroys the retinal pigment cells. Retinal tissue engineering provides a suitable environment for the growth of retinal pigment epithelium cells using different scaffolds. These scaffolds may cause interior pressure changes in eyes and thus, causes disease of the separation of pigment and retinal epithelial cells. Therefore, the purpose of this study was to simulate gelatin, gelatin-chitosan and poly-caprolactone scaffolds in the retina and compare the pressure gradient and the effect of thickness on the pressure gradient.
Materials & Methods: In the present experimental study, in the first stage, three gelatin, gelatin-chitosan and poly-caprolactone scaffolds were simulated to examine the average scaffold pressure using COMSOL 5.1.1 software and Darcy law. In the next step, a gelatin-chitosan scaffold with thicknesses of 10 and 20 micron was simulated with Darcy law, to examine the effect of thickness on average pressure.
Findings: The output pressure of the gelatin scaffold was calculated as 308.800Pa Which was less than the pressure level of the caroid layer And it was less than the output pressure of other scaffolds. The average pressure of gelatin-chitosan scaffold with thicknesses of 10 and 20 micron was 1997.31 and 2003.13 respectively in the last step.
Conclusion: The gelatin scaffold produces a moderate lower pressure than the gelatin-chitosan scaffold and poly-caprolactone in the retina and it is more suitable than other scaffolds. In the simulation of gelatin-chitosan scaffold, increasing the thickness causes increased pressure and retinal impairment.

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Hyaluronic acid (HA) is a natural and linear polymer that finds a wide-range of applications in medicine, cosmetics, and nutraceuticals because of excellent viscoelasticity, high moisture retention capacity, high biocompatibility and non-toxicity. HA has been recently produced in industrial scale by Streptococcal species. Streptococci are nutritionally fastidious lactic acid bacteria and cannot synthesize some amino acids. Therefore, it is necessary to study and select some commercial culture media for their growth. In this study, HA production and hyaluronidase activity of S. zooepidemicus ATCC 43079 in three culture media were investigated. Regarding the detrimental effect of this enzyme on HA amount, 6-O-Palmitoyl-L-ascorbic acid as hyaluronidase inhibitor was added to culture medium during fermentation. The effect of three variables consisted of glucose concentration, yeast extract concentration and medium pH each at 3 levels were considered and (response surface methodology (RSM) was used for statistical design of experiments to study the HA production by this strain. The results showed that maximum HA production was obtained when glucose concentration, yeast extract concentration and pH were 21.2 g L^-1, 43.6 g L^-1 and 6.6, respectively. Under optimum conditions, HA was produced as 370±15 mg L^-1 which was ~150% more than of HA concentration in basal medium (150±10 mg L^-1) and productivity reached 56.74 g L^-1 h^-1 that was increased 2 fold compared to central point.