Preparation And Performance Study Of Core-shell Structure Conductive Drug Loaded Electrospun Fiber And High Conductive Knitted Fabric Cardiac Patch

Myocardial infarction（MI）is a result of coronary artery occlusion and one of the main causes of death in cardiovascular diseases.MI is the leading cause of death among urban and rural residents.At present,the main methods for treating MI are to restore infarcted tissue through cells,drugs,genes,and cell growth factors.However,they are not without limitations.These conventional therapies may help treat affected myocardium,but they cannot repair or restore cardiac tissue.So far,there are two main methods for cardiac function reconstruction after MI,including injectable biomaterials and engineered cardiac patches.Among them,the use of engineered cardiac patches（ECPs）to restore damaged cardiac tissue is a promising strategy.Therefore,the use of biodegradable materials,drugs,and conductive polymers to prepare ECPs is an effective method for promoting the repair and regeneration of MI areas.Based on the properties of biomaterials,this paper selects biocompatible materials such as polylactic acid（PLA）,aspirin（AS）,polypyrrole（PPy）,silk knitted fabric,graphite oxide（GO）,pyrrole（Py）to prepare three different kinds of ECPs.The optimal concentration of aspirin（AS）,polypyrrole（PPy）,graphite oxide（GO）and pyrrole（Py）was selected by adjusting the process parameters in the process of coaxial electrospinning,in-situ chemical reduction and in-situ oxidative polymerization.On this basis,different methods were used to prepare ECPs,and their surface morphology,conductivity,mechanical properties,surface chemical composition,thermal properties,hydrophilicity,hydrophobicity,degradation performance,and drug release performance were studied and characterized,providing a certain experimental basis and new research ideas for the preparation of ECPs.The main research content and conclusions of this article are as follows:（1）Coaxial electrospinning was used to prepare PLA-PLA/AS core-shell drug loaded nanofiber membranes with different AS concentrations.Analysis showed that the fiber diameter significantly increased with the increase of AS concentration.Compared to the pure PLA core-shell nanofiber membrane,it was found that the tensile strain and Young’s modulus of the fiber membrane increased with the addition of drug AS,while the ultimate tensile strength decreased.As the concentration of AS increases,there is no significant change in the surface temperature of the fiber membrane in the wet state,indicating that the fiber membrane has good thermal stability,while the addition of AS does not significantly improve its hydrophilic and hydrophobic properties.As the concentration of AS increases,the pre release amount of drugs also significantly increases,and the release curve tends to be relatively stable with time.At 336 h,the cumulative release amount of drugs from 7%PLA-7%PLA/2%AS fiber membrane reaches the maximum value of 71%.（2）A core-shell conductive drug loaded nanofiber membrane was prepared using coaxial electrospinning,with polylactic acid/polypyrrole（PLA/PPy）as the shell layer and polylactic acid/aspirin（PLA/AS）as the core layer.Analysis revealed that the cross-section of the fiber exhibited a core-shell bilayer structure.The fiber diameter decreases with the increase of PPy concentration,and there is aggregation of conductive particles on the fiber surface,which can increase the adhesion ability of cardiac patches to the MI region.By adding different concentrations of PPy to the shell layer,the conductivity and mechanical toughness of the fiber membrane were improved.The conductivity of7%PLA/2%AS-7%PLA/0.1%PPy fiber membrane increased to 8.9×10^-5 S/cm promoted the cumulative release of drug AS,with a drug release efficiency of over 92%and a longer release time of 336 h.The improved cardiac patch was applied to the pig heart,and the stability and self-adhesion of its entire structure were found.（3）RGO/PPy/silk knitted fabric was prepared by in-situ polymerization using GO and Py.The changes in surface morphology,structure,and conductivity of r GO/PPy/silk knitted fabric were studied under different GO and Py concentrations.Research has shown that compared to PPy/silk knitted fabrics,r GO/PPy/silk knitted fabrics exhibit uniform distribution of PPy particles,high conductivity,and good conductivity stability when GO concentration is 1 g/L and Py concentration is 8/12/14/16 g/L,respectively.When the GO concentration is 1 g/L and Py concentration is 16 g/L,the conductivity reaches 7.08×10^-1 S/cm.As the Py concentration increases,the thermal stability of conductive silk knitted fabrics also increases.The rough conductive particles on the surface of the fabric and certain mechanical properties make it suitable for the adhesion and growth of myocardial cells.In summary,three different engineering cardiac patch materials all have good conductivity,special fiber morphology,and functional applications,each with its own advantages.After further biological performance research,they can be applied to the preparation of ECPs.This study not only provides a certain experimental basis for the preparation of biocompatible cardiac patches,but also provides new research ideas for the repair design of MI.