Study On The Stability And Disinfection Effect Of Iodine-chitooligosaccharides

Objectives: Explore the optimal conditions for the hydrolysis of over80%deacetylated chitosan by hydrogen peroxide, explore the conditions to stabilize iodineafter the coordination of aqueous chitooligosaccharides with iodine, evaluate thedisinfection effect of iodine-chitooligosaccharides complex.Methods:1. Hydrolysis of chitosan by hydrogen peroxide: Hydrogen peroxide wasused to hydrolyze chitosan with over80%degree of deacetylation, with the aid ofOrthogonal Array Testing Strategy (OATS), an optimal condition was found, underwhich the hydrolysis was completed in a single step, producing aqueousoligosaccharides solution.2. Stability of iodine-chitooligosaccharides solution: Into chitooligosaccharidessolution at certain concentration, iodine and potassium iodide were added to form theiodine-chitooligosaccharides complex.The complex solution was then divided intothree groups, The one group with four different PH, The another group were added ICof different concentrations.The effective iodine concentration was periodicallymonitored and compared against the initial iodine concentration, with the percentageof the remaining iodine concentration over initial iodine concentration calculated. Themonitoring period spanned over12months.3. Antibacterial test of iodine-chitooligosaccharides solution: Quantitative SuspensionTest Method (QSTM) was adopted to evaluate the disinfection effects of theiodine-chitooligosaccharides solution (0.5%iodine content) against three coexistingbacteria.Results:1. Using Orthogonal Array Testing Strategy (OATS), nine experiments were performed as shown in Table L9(34)(four factors and three levels), A3B3C1D3was identified as the best reaction condition, which is at chitosan concentration of11%, hydrogen peroxide concentration of6%, temperature of88oC, and total volumeof3000mL. Under this condition, an aqueous solution of chitooligosaccharides wasobtained in a single step. The final solution is brown, with sugar-like sweet smell,The content of oligosaccharides containing2–20glucosamine units.2. In each of the three testing groups, there was a relatively stable formulation.Among them, the formulation of Test#12in the third group showed the best stabilitywith the effective iodine concentration maintained at90%.3. In the quantitative suspension test, the disinfection effect ofiodine-chitooligosaccharides solution containing0.5%effective iodine was evaluatedagainst Staphylococcus aureus, Escherichia coli, and Candida albicans. The results at1minute,2.5minute, and5minute were compared with commercial iodizedsurfactants containing0.5%effective iodine. The disinfectional effect ofiodine-chitooligosaccharides against Staphylococcus aureus is slightly worse than thecommercial iodized surfactants, the effect at2.5minute and5minute are comparableto the commercial product.In the case of Escherichia coli,iodine-chitooligosaccharides shows similar performance with the commercial iodinecomplex at all three time points. On Candida albicans, iodine-chitooligosaccharidesexhibits inferior effect at1minute and2.5minute, but with increasing time, it reachesthe same effect as commercial iodine complex at5minute. This result indicates thatthe iodine-chitooligosaccharides solution has sustained delivery function, can slowlyrelease iodine in a prolonged period of time. The minimum bactericidal concentrationexperiments show, iodine-Chitooligosaccharides is a strong antibacterial agent.Conclusion:1. Hydrogen peroxide hydrolysis of chitosan: The optimal conditionsare: chitosan concentration of11%(w/v), hydrogen peroxide concentration of6%(w/v), temperature of88oC, and total volume of3000mL.2. Iodine-chitooligosaccharides Stability: recipe with best stability is7%I2,5%KI, and30%IC(w/v)in the hydrolysate.3. Iodine-chitooligosaccharides is a good disinfectant on Staphylococcus aureus,Escherichia coli, and Candida albicans. By iodine-Chitooligosaccharides againstStaphylococcus aureus, Escherichia coli, Candida albicans antimicrobial activity testsand the minimum bactericidal concentration proved, Iodine-Chitooligosaccharidesbactericidal effect and iodine commercially available surfactants fairly.