Chitosan And Antibacterial Activity Evaluation

Chitosan, which is a linear polysaccharide composed ofα-amino-D-glucan linked byβ-1,4-glycosidic bonds, is prepared by alkaline deacetylation of chitin. It is insoluble in water or alkaline solution, but can dissolve in majority of organic acids. Chitosan has many unique features sucn as nontoxicity, degradability, cell affinity and biocompatibility. Chitosan is the only alkaline polysaccharide with many amino and hydroxyl groups distributing along the macro-molecule chain, which can form intra-and inter-molecular hydrogen bonds. These features cause high crystallinity and low solubility of Chitosan, limiting its application enormously. This study compounded chitosan with cyclodextrin or prepared chitosan self-aggregates at nano-scale,using Ivermectin (IVM) as model drug, in order to design the carriers loading hydrophobic drugs.Chitosan and cyclodextrin compounds were preparaed by cross-linking with glutaraldehyde. mPEG-graft-Chitosan was prepared through the functional group coupling's method. These materials were characterized structurally and assessd for drug-loading capacity.Antibacterial experiment are carried against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), the result indicated that 20mg/L Chitosan with molecular weight about 100,000 had obviously bacteriostasis effect, the bacteriostasis effect of modified Chitosan against E.coli and S.aureus was all lower than that of non-modified chitosan.β-cyclodextrin and Chitosan (CS) compound were used as carriers for IVM for inclusion. Theβ-cyclodextrin-IVM was prepared by saturated solution andβ-cyclodextrin-Chitosan was prepared by crossing linking with glutaraldehyde; Ivermectin was loaded by incubation method and the loading efficiency and association efficiency was determined. The properties of them were characterized with the differential scanning calorimetry (DSC), X-beam diffraction (X-Ray), the Fourier infrared spectrum (FTIR), scanning electron microscope (SEM). The result indicates the proportion ofβ-CD and IVM was 6:1, the loading efficiency and association efficiency was 30.08%±0.11% and 29.54%±1.21%, Respectively. The average loading efficiency and association efficiency ofβ-CD-CS-IVM was 10.2%±5.75% and 15.13±3.43%, Respectively.β-CD-IVM andβ-CD-CS-IVM compound have been formed by FTIR, the X-beam diffraction and the DSC analysis confirmation,at the same time, the loading efficiency and association efficiency ofβ-CD-CS-IVM is lower thanβ-CD-IVM's. The surface texture ofβ-CD-CS was observed with the electron microscope scanning, indicated thatβ-CD-CS particle was porous. The average loading efficiency and association efficiency ofβ-CD-CS-IVM was affected by the proportion ofβ-CD and CS, time and temperature. The result indicated that when the glutaric dialdehyde was used as the crosslinking agent, the temperature is 60℃, the the weight proportion of (β-CD/Chitosan) is 9:1, The average loading efficiency ofβ-CD-CS was largest.Another part of this study is synthesis of methyl polyethylene glycol monomethyl ether grafted Chitosan (mPEG-g-CS) through the coupling reaction of functional groups, and study its characterization of the structure and properties, according to which, nanoautopolymer of mPEG-g-CS is prepared. Compared withβ-cyclodextrin-Chitosan particles, the rate of drug loading and encapsulation efficiency increased to 19.65%±2.05% and 14.51%±1.36%, respectively, in vitro release results show that the sustained release effect of nano-autopolymer of mPEG-g-CS was better thanβ-CD-CS-IVM,which has cumulatively released 98.26% in 8 hours.