The objective of this study was to evaluate and compare the cytotoxicity and genotoxicity on human fibroblast cell lines of sodium hypochlorite (NaOCl), chitosan and propolis as root canal irrigating solutions. Human fibroblast cells were exposed to chitosan, propolis and NaOCl for 4 and 24 h. Cell viability was assessed by 2,3-bis-(2methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide, and oxidative DNA damage was assessed by determination of 8-hydroxydeoxyguanosine (8-OHdG) level with an ELISA kit. The data of cell cytotoxicity were analysed statistically using a test of one-way analysis of variance at a significance level of p < 0.05. In the NaOCI group, the 8-OHdG level was higher than in the chitosan group, but there was no statistical difference when compared with the other groups (p < 0.05). It was determined that the irrigation solutions were cytotoxic, depending on the dose and time. NaOCl was the most toxic solution after both 4and 24 h of exposure (p < 0.05). Chitosan and propolis may be alternatives to NaOCl for irrigation solutions, because they are both less toxic and produce less oxidative DNA damage.
In order to investigate the biocatalytic properties of a-amylase on a composite cryogel matrix with immobilized metal affinity chromatography, Cu þ2 -attached poly(2-hydroxyethyl methacrylate) (Cu þ2 -PHEMA) beads, (2 mm size) were synthesized, then composite cryogel column was prepared by composing beads and PHEMA cryogels. After the preparation of Cu þ2 -PHEMA beads embedded cryogel column (Cu þ2 -BEC), some experiments were tested. Accordingly, the highest adsorption capacity (676.8 mg/g particles) of cryogels was achieved at acetate buffer of pH 5.0 with initial a-amylase concentration of 4 mg/mL. Immobilized enzyme has more stable pH range, between 6 and 7.5 than, the free one. Immobilization also increased the optimal activity from 25 to temperature range of 25-35 C. V max and K m of a-amylase were detected as 1.149 U/mg protein, and 11.6 Â 10 À1 mM, respectively. a-Amylase was utilized 35 times repeatedly without losing the productivity.
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