The Effect Of Plasticiser Addition On The Performance Of Copper-loaded Coatings Study

The advent and widespread use of modern medical equipment and devices has greatly increased the cure rate of diseases,but also made problems such as nosocomial infections and thrombosis more prominent.There is an urgent need for a multifunctional coating technology to effectively reduce the chances of biofilm and thrombosis.Chitosan,a natural cationic polysaccharide,is widely used as an antibacterial coating and drug carrier due to its multiple biological functions.In previous research,copper ions with multiple biological functions were grafted onto chitosan through chelation reactions to obtain copper-loaded chitosan coatings with excellent antibacterial,anticoagulant and anti-infective functions.However,the coating is brittle and inflexible,and the surface of the coating is prone to a large number of cracks and even peeling,making the original antibacterial and anti-infection effects of the coating significantly reduced.In this study,the effect of the addition of two types of plasticisers on the structure and properties of the copper-loaded chitosan coating was investigated,and the plasticising effect of the plasticisers in different ratios on the coating was studied.At the same time,the antibacterial and anti-infection functions of the coatings were further evaluated using in vitro antibacterial tests and animal experiments,as well as the biosafety of the coatings.The main findings of this paper are as follows:（1）Compared with polyvinyl alcohol,glycerol has a more significant plasticising effect on the copper-loaded coating,and by comparing the effects of different plasticisers and different addition ratios on the mechanical properties of the coating,it is concluded that the mechanical properties of the plasticised copper-loaded coating are best when the addition ratio of each component of the coating is PVA:G:CS=2:5:10.The hydroxyl group on the glycerol molecule and the hydroxyl group on the chitosan chain undergo strong hydrogen bonding,which reduces the hydrogen bonding within the chitosan molecule,effectively improving the mechanical properties of the coating itself and achieving a better plasticizing effect.The plasticised coating material was prepared on the surface of medical catheters and bent at 90°.No cracks were found in the coating,and the plasticisation of the CS/Cu coating material was achieved.（2）The addition of the plasticiser changes the surface properties of the copper-loaded coating and increases the hydrophilicity of the coating.At the same time,the thermal stability of the plasticised coating is further improved and the release rate of copper ions is slower and more uniform than that of the original coating,which is conducive to the long-lasting antibacterial and anti-inflammatory effects of the coating.（3）The in vitro antibacterial test results of the plasticised copper-loaded coating showed that the plasticised coating still had significant antibacterial properties and did not show any significant decrease compared with the original coating.The results showed that the antibacterial effect of the CS/Cu/PVA/G coating was better than that of the CS/Cu coating,with the antibacterial rate of the CS/Cu/PVA/G coated samples remaining at around 70%two months after implantation.The staining of rat urethral tissue sections also showed no significant difference in inflammatory cell infiltration in the surrounding tissues after implantation of the CS/Cu/PVA/G coated samples.The antimicrobial durability of the coating was closely related to the increased degree of cross-linking between the molecular chains within the organic framework and the enhanced chelation of chitosan with Cu²⁺,which effectively slowed down the rate of Cu²⁺release and enabled the plasticised copper-loaded coating to exhibit excellent results of antimicrobial and anti-inflammatory durable effects.