Several Preparation Technologies Of PLA-based Composite Films And Its Antibacterial Properties

In the process of storage and use of medical devices,it is inevitable to be infected by various types of bacteria.The preparation of composite films with antibacterial function on its surface is an effective way to solve bacterial infection.In this paper,monolayer and bilayer composite films of drug based polylactic acid(PLA)were deposited on single crystal silicon wafer,titanium wafer and KBr salt sheet substrate by low-energy electron beam deposition(EBD),laser assisted electron beam deposition(PLD+EBD)and the combination of EBD and ultrasonic atomization(UA)techniques,respectively.The composition,structure and morphology of various composite films were analyzed,and their antibacterial and sustained-release antibacterial properties were tested.The correlation between the kinetic release mechanism of the drug and its antibacterial activities was investigated.The main works are as follows:Three kinds of PLA-CIP composite films with different target mass ratios were prepared by EBD using the PLA and ciprofloxacin(CIP)powder as targets.The thickness of the composite films is between 2.6 and 3.0 ?m,studies on the composition and structure of the composite films show that there are characteristic functional groups of CIP in the composite films,and the molecular structure is not damaged.The films show uniform granular or spherical morphology on the substrate.When the mass ratio of the target is 1:1,the composite films has the best comprehensive properties and good antibacterial effect which against S.aureus is better than that of E.coli,and the sustained-release antibacterial activity can reach 7 d,even after heat treatment at 180 ?,the films can still maintain its original composition,structure and morphology,and the antibacterial effect is comparable to that of the non-heat treated composite films.PLA-CIP/HA-Van composite films were prepared by PLD + EBD,PLA-CIP(1:1)composite films were prepared by EBD at the bottom layer,and HA-Van [hydroxyapatite(HA): vancomycin(Van)= 6:1] composite films were prepared by PLD on the upper layer.The thickness of bilayer composite films is about 5.22?m,antibacterial effect of the composite films on S.aureus was more significant than that of E.coli.The sustained-release period was 3 days longer than that of PLA-CIP monolayer composite films to achieve equivalent sustained release effect,and the existence of the outer composite films could control the release of CIP in the bottom layer.After 10 days of sustained release in saline,the cumulative release concentration of CIP was about 19?g/m L.PLA-CIP/PU-Paraffin-Van bilayer composite films were prepared by the combination of EBD and ultrasonic atomization(UA)techniques,PLA-CIP(1:1)composite films were prepared by EBD at the bottom layer,and PU-Paraffin-Van [polyurethane(PU): paraffin(Paraffin): Van = 2:2:1] composite films were prepared by EBD + UA on the outer layer.The thickness of the bilayer composite films was about 6.44?m,and has excellent antibacterial and sustained-release antibacterial effects against S.aureus,which the sustained-release period can reach 14 days.The double layer composite films was deposited on the surface of titanium rod prosthesis with a diameter of 4mm sprayed with HA coatings,after 4 weeks of implantation,the liver and kidney function of rabbits was measured.The results showed that the use of the antibacterial films had little effect on the liver and kidney function of rabbits.