Electrophoretic deposition, microstructure and selected properties of zein/cloves coatings on 316L stainless steel

In the present study, we develop zein coatings containing cloves (flower buds of the Syzygium aromaticum tree, a well-known aromatic natural herb) on stainless steel substrates via electrophoretic deposition. The antibacterial activity, drug release, surface (morphology, roughness, and wettability), corrosion, and adhesion properties of the produced zein/cloves coatings were elucidated in detail. The coatings deposited an applied electric field of 20 V/cm with a deposition time of 5 min yielded uniform zein/cloves coatings with a thickness of-9 mu m, which was confirmed by scanning electron microscopy. Fourier transformation infrared spectroscopy analysis confirmed the presence of zein and cloves functional groups in the zein/cloves coatings. The results of tape tests exhibited that the adhesion between the coatings and the substrate was rated as '5B' (Excellent) according to the ASTM-D3359 standard. The zein/cloves coatings exhibited an average roughness of 0.8 +/- 0.05 and a contact angle of 60 degrees +/- 2 degrees, making them appropriate for orthopedic applications. The antibacterial studies exhibited that the zein/cloves coatings developed zone of inhibition against Staphylococcus aureus and Escherichia coli, con-firming the strong antibacterial potential of the coatings. UV-Vis Spectroscopy elucidated that after one week of immersion in phosphate buffer saline,-65 % of eugenol was released from the zein/cloves coatings. Further-more, the zein/cloves coatings improved the corrosion resistance by-3 orders of magnitude compared to bare 316L stainless steel. Antimicrobial and drug release studies confirmed that the zein/cloves coatings can provide a targeted drug delivery system with a potent antimicrobial effect.