The Antibacterial Proprety And Applications Of Quaternary Chitosan With The Second Antiseptic

Chitosan is a natural biological macromolecule with rich source.It possessed many excellent properties such as antimicrobial ability,biocompatibility,hygroscopic and moisture resistance capacity,film-forming ability,flocculation and biodegradability,so chitosan have wide range of applications in food,medicine,paper making,water desalination,wastewater treatment or other biological and chemical industry.As one of the chitosan quaternary ammonium derivatives,hydroxypropyltrimethyl ammonium chloride chitosan(HACC)broke the limit that chitosan can only dissolve in acidic conditions and improved antimicrobial activity due to the introduction of the quaternary ammonium groups.However,good antimicrobial property means some accompanied,so the balance of disinfection and cytotoxicity is an essentially important task.One can take advantage of the compatibility between antiseptics.On the one hand,it can reduce the dosage of each antiseptic;on the other hand,it can give full play to a synergetic effect of antimicrobial agents,for ensuring good antiseptic resistance and biocompatibility.This study have researched the minimum inhibition concentration(MIC)and cytotoxicity of HACC,polyhexamethylene biguanide(PHMB)and polyquaternium-1(PQ-1)respectively through agar plate dilution assay and MTT assay.Results showed that bacteriostatic effect of PHMB was superior to PQ-1 within the scope of the safe concentration,therefore,choosing PHMB to combine with HACC to balance the sterilization and biological safety.Combining with the studies of optical microscopic imaging and fluorescence spectra method,we researched the relationship between the microstate and antimicrobial effect of HACC-PHMB in aqueous solution.And applying the disinfection system into the contact lens care solution for the first time.The specific work was as follows:Firstly,we researched the minimum inhibition concentration(MIC)and cytotoxicity of HACC.We found that when HACC were at MIC,it had certain poisonous to the cells,which suggesting that HACC alone cannot balance both antimicrobial effect and biological compatibility.In view of the limitations of single antiseptic,considering to taking HACC as the first antiseptic,and introducing the second antiseptic to balance the sterilization and biological compatibility.Due to the cationic characteristics of HACC,choosing cationic antiseptics PHMB or PQ-1 to combine with HACC.And results showed PHMB was more suitable to form double disinfection system.Secondly,considering the limitations of single antiseptic,so combining antiseptics together to form the HACC-PHMB disinfection system was reasonable.We have studied the antimicrobial ability and cell toxicity of HACC/PHMB at different weight ratios of 10/1,30/1,50/1 100/1 and 150/1.The disinfection system of 100/1 and 150/1 exhibited qualified sterilization rate and cell proliferation rates,and 150/1 was the most effective sterilization.The results show that the HACC and PHMB had good compatibility,and could produce superior synergistic bactericidal effect.Their combination could meet the requirements of sterilization and biological nontoxic.Thirdly,the relationship between antimicrobial ability and microstructure of above complex solutions were studied by optical microscopy imaging method,and the fluorescence spectrum method was used to explore the internal driving force that leading to the microstates changes of complex.The research results showed that single HACC molecules were crowed together loosely in borate buffer,and there were morphological change of the HACC-PHMB aggregates after adding PHMB.When small amount of PHMB was added,HACC-PHMB aggregation particles were small and dispersed well in solution and exhibited decentralized state,which stated that the hydrophobic effect between HACC and PHMB weakened the interactions of HACC-self,making HACC-HACC separate each other,and HACC-PHMB aggregates were formed.Besides,causing the hydrophobic part of the two molecules curling up inside the aggregates,while the hydrophilic part,such as NH2 and NH4+,gathering in the aggregates surface.These exposed cation promoted the aggregates interacting with microorganisms on cell external membrane,leading to more deaths of more microorganisms compared to HACC self-aggregates.When PHMB was at bigger content,the massive and compact HACC-PHMB aggregates were formed.Those massive and compact HACC-PHMB aggregates attracted negatively charged outer membrane of microbial cell by electrostatic interacting,then larger area coverage on the surface of bacteria or fungus prevented the absorption of nutrients and discharge of metabolic waste at a greater extent,interfering the microbial growth and reproduction.So it could be implied that cell external interaction was the main collaborative antiseptic way when HACC/PHMB were at bigger ratios.Finally,we applied HACC-PHMB complex with excellent antimicrobial ability and good biocompatibility into contact lens care solution as disinfection system,and mixed them with cleaning agent,chelating agent and osmotic pressure regulator.The contact lens care samples could kill more than 90%fungus and 99.9%bacteria,and no cytotoxicity were found.Physical and chemical performance study showed that the pH,osmotic pressure and clarity of the sample were within the qualified scope according to standard.Sample also exhibited good moisturizing capacity and cleaning effect,and revealed similar or better performance compared with commercially available products.The content detection method of HACC and PHMB,the two kinds of cationic antiseptics,were under researching.The analytic results showed that HACC content could determined by HPLC method,and PHMB could detected by ultraviolet absorption method by or HPLC,and the former showed good linear correlation.