Micro/nanoscale surface engineering to enhance hemocompatibility and reduce bacterial adhesion for cardiovascular implants

Precise engineering of surface properties is essential for improving bio/hemocompatibility of medical implants. In this study, potential of electrospraying (ES) as a coating method to control surface properties was evaluated in vitro. Poly (lactic acid) was coated on 316 L stainless steel plates by ES and spin-coating methods. Surface topography and morphology were studied using confocal and scanning electron microscope (SEM), respectively. Surface hydrophobicity and mechanical properties were investigated by contact angle and nanoindentation tests. Hemocompatibility of samples evaluated using protein adsorption, hemolysis, blood coagulation, complement system and leukocyte activation experiments. Platelet response to the coatings was examined using LDH assay, SEM and ELISA tests. Cell viability studies performed on human endothelial cells using MTT assay and SEM after 1, 4 and 7 days. SEM was used to consider formation of pseudomonas aeruginosa biofilms on the coatings. The results showed that ES increased hydrophobicity (122֯ vs 90֯) and surface roughness (2 μm vs 1.2 μm) but reduced surface stiffness (200 MPa vs 10800 MPa) in comparison to spin-coated samples. ES-coatings had microbead/nanofiber morphology while spin-coated samples had micro/nanoporous structure. Importantly, an almost confluent layer of endothelial cells was observed on ES-coated samples after 4 days in contrast to spin-coated ones. Various blood experiments revealed both coatings were hemocompatible and there was no significant difference among ES and spin-coated samples. Furthermore, ES-coated samples showed significantly lower propensity for biofilm formation. In conclusion, in vitro results revealed potential of ES to engineer different coating properties including hemo/biocompatibility and biofilm resistance for cardiovascular implants applications.