Preparation And Study Of Antibacterial Properties Of Self-assembling Antibacterial Coatings On The Surface Of PLGA Films

Poly(lactic acid-co-glycolic acid)copolymer(PLGA)is a biodegradable material,which is widely used in many biomedicine fields,such as drug control carriers,medical dressings and implant materials.Due to the surface carboxyl and ester functional groups PLGA is easy to be contaminated by bacteria,which limits its application as biomedical materials or packaging materials and it is easy to cause secondary pollution of bacteria.In this thesis,the PLGA surface was negatively ionized by self-assembly and cross-linked with cationic antibacterial agent polyhexamethylene guanidine hydrochloride(PHMG),polylysine hydrochloride(PLL)and PAMAM through ionic crosslinking.Three kinds of PLGA materials with antibacterial surface were obtained by the method,and the details are as follows:First,we use DL-lactic acid(DL-La)and DL-malic acid(DL-Ma)as raw materials to prepare PLMA through polycondensation.And the PLMA was characterized by ~1H-NMR,GPC and FT-IR.Secondly,PLGA film is prepared by solvent-casting method,and PLMA is then coated on PLGA film to obtain PLGA-PLMA film containing carboxyl groups on the surface.Subsequently,the PLGA-PLMA film was immersed in0.1 mol/L Na OH solution to form carboxyl anions on the surface,and then the film was placed in a solution containing three polycations including PHMG,PLL and PAMAM solutions to produce films with three different cationic surfaces,which we named respectively:PLGA-PHMG film,PLGA-PLL film and PLGA-PAMAM film.Then we used SEM,XPS and AFM tests to characterize the properties of these films and proved that the polycations successfully self-assembled on the surface of the PLGA film.Finally,through the antibacterial performance test results of the three antibacterial films,it can be known that all of the three antibacterial films have good antibacterial abilities.PLGA-PHMG film shows the best antibacterial properties.Its antibacterial rate against10~8 CFU/m L E.coli reaches 99.9%at 5 min,and its antibacterial rate against S.aureus is 90.6%,while PLGA-PLL film at 30 min,the inhibition rate of E.coli reached 99.9%,and the inhibition rate of S.aureus was 76.5%.PLGA-PAMAM film has a bacteriostatic rate of over 99.99%for S.aureus with a lower concentration at 20 min,and an E.coli bacteriostatic rate of 98.8%.