Development of adherent antimicrobial copper coatings on stainless steel for healthcare applications

Abstract

Copper coatings were fabricated using an environmentally sustainable non-cyanide electrodeposition technique. By following four-stage acid pickling treatment of the substrate and optimum parameters during electrodeposition, adhesion strength up to 9 MPa was obtained. Four different copper coatings were fabricated by varying CuSO<inf>4</inf>. 5H<inf>2</inf>O concentration in an electrolyte (10, 15, 30, and 45 g/L) to understand nucleation and growth mechanism and surface texture evolution. Nano-nodular morphology of the deposited copper marks a significant feature. It increases the fraction of grain boundaries in it. The grazing incidence X-ray diffraction analysis revealed the preferred orientation along the (111) plane with the presence of residual compressive stresses (in the range of 24.90–273.92 MPa). Surface texture studies indicated that the coating had an abundance of nano-scaled protruding structures with surface roughness’s Sa in the range of 2.507–1.674 µm (Ra in a range of 1.714–1.235 µm). It offers 3D contact with microbes. The developed coating had increased hardness (41.93%), scratch resistance (58.77%), and 9 MPa adhesion strength with the substrate. Initially, copper coatings had hydrophobicity against water (initial contact angle in the range of 134–139°). The extent of hydrophobicity decreased with exposure time. The developed coatings exhibited significant antimicrobial activity. Antimicrobial studies using the cell viability technique indicated that the coating exhibits toxicity against Escherichia coli (ATCC25922) and Staphylococcus aureus (MCC2408) microbes. 100% reduction of the survival of microbes is observed after 4 h of exposure. Graphical Abstract: [Figure not available: see fulltext.]. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.