Ginseng encapsulated Poly(Lactic-co-Glycolic Acid)/ Polyaniline microcapsules coated on stainless steel 316L using electrodeposition technique for drug-eluting stent application

Abstract

Drug-eluting stent (DES) has successfully minimised the occurrence of restenosis and in-stent neointimal formation. However, its drawback of polymer hypersensitivity is often led to late-stent thrombosis. Besides, incomplete coating and bridging on stent surfaces as well as rapid release of anti-proliferative drugs to the site of implantation have contributed to late endotheliasation. The incorporation of ginseng within biodegradable polymer coating will address these issues due to its specific therapeutic values. Therefore, 30 mg ginseng was encapsulated in poly (lactic-co-glycolic acid) (PLGA) microcapsules to be electrodeposited as a coating on stainless steel 316L (SS316L). A proficient technique of electrodeposition was performed at different currents (1 - 3 mA) and deposition times (20 - 60 seconds) while different polyaniline (PANI) compositions (0.5 - 2.0 mg) were also adopted in the electrodeposition process to drive the formation of microcapsules coating. Based on different currents and deposition times, it was found that electrodeposition with addition of PANI conducted at 2 mA current and 40 seconds deposition time has formed low wettability and uniform microcapsules coating through the analyses of ATR-FTIR, SEM and contact angle. Reduction in current or deposition time caused less attachment of microcapsules coating with high wettability records. Increasing current or prolonging deposition time has led to debris formation and melted microcapsules with non-uniform wettability measurements. The colour of electrolytes was also changed from milky white to dark yellow when the current and the deposition time increased. Based on different composition of PANI, the utilisation of 1.5 mg PANI has assisted the formation of stable, uniform and rounded microcapsules coating with appropriate wettability and surface roughness through the ATR-FTIR, XPS, SEM, AFM and contact angle analyses. Low PANI content (0.5 mg) was not enough to drive the formation of microcapsules coating while higher content of PANI (2.0 mg) caused the deposition of melted microcapsules. A month coating stability analysis showed that the coating stability was improved at the utilisation of 1.5 mg PANI with moderate PLGA degradation and less appearance of melted microcapsules. The similar coating also has promoted greater endothelial cell proliferation and attachment compared to other coating variation through MTT assay and VP-SEM analyses. The capabilities of ginseng encapsulated PLGA/PANI microcapsules coating in delivering its therapeutic values would be beneficial in addressing the complication of current DES.