Preparation,Characterization And Antifungal Properties Of Chitosan-Graphene Oxide

In this thesis,three different molecular weights of CS and GO were used to obtain CS-GO and its antifungal activity against F.graminearum was evaluated.In addition,CS-GO was oxidized and sulfonated to obtain water-dispersed composite materials OGC and SGC,and their antifungal activity against phytopathogens was evaluated.This study provides a candidate nanoformulation for pathogenic fungal control in plants.The main research contents are as follows:(1)GO and CS-GO composites were prepared and characterized.GO with good water dispersion was prepared by Hummer’s method,and chitosan with different molecular weights was crosslinked to prepare CS-GO.After characterization by X-ray diffractometry(XRD),Field emission scanning electron microscopy(FESEM)and Fourier transform infrared spectroscopy(FTIR),the results indicated that the amidation reaction occurred between the amino group in CS and the carboxyl group in GO,CSGO was synthesized successfully.(2)The antifungal activity of CS-GO composites against F.graminearum was evaluated.The effects of different molecular weights(2.5W Da,5W Da,10 W Da)of chitosan and different proportions of GO and CS on the inhibition of F.graminearum were investigated.It was found that the antifungal effect of the CS-GO was obviously better than GO or CS alone.When the mass of GO was 10% and the molecular weight of CS was 5W Da,the antifungal effect was the best.At the concentration of 50 μg/m L,the antifungal rate of CS-GO against the mycelium growth of F.graminearum was95.55%.When the concentration was 12.5 μg/m L,the inhibition effect on F.graminearum reached about 80%,and the control effect in the field reached 74.35%.(3)5W CS-GO(10%)with the best antifungal activities was modified and the antifungal properties were studied.SGC was prepared using a sulfonating agent mixed with chlorosulfonic acid and formamide,and OGC was prepared using nitrogen dioxide as an oxidant.And they are used to inhibit phytopathogens.The results showed that the composite showed good antifungal activity after sulfonation and oxidation.At 500μg/m L,the antifungal activity of SGC on mycelium growth of S.sclerotiorum,F.graminearum and Cucumber fusarium wilt was 77.44%,82.41% and 74.36%,respectively.At 500 μg/m L,the antifungal activity of OGC on mycelium growth S.sclerotiorum,F.graminearum and Cucumber fusarium wilt was 73.37%,80.69%,and75.49%,respectively.