Application of oxidized metallic surfaces as a medium to store biochemical agents with antimicrobial properties

Creating air-stable antimicrobial metallic surfaces that are resistant to washing could impact both food handling and medical applications. This work analyzes the release kinetics of nisin nanoparticles (an antimicrobial peptide) from cracked and uncracked oxide films on stainless steel and titanium to develop an antibacterial metallic surface. The cracked morphology creates mudflat crack patterns that penetrate approximately 4 μm into the substrate, deeper than the 100 nm thick oxides. The desorption of the peptide from uncracked oxides on stainless steel is promoted by acidic pH, slows down at neutral, and stops at basic pH. Increases in temperature contribute to significant accelerated desorption process only at acidic pH. Cracked oxide films effectively immobilized nisin in the cracks. For Ti-6Al-4 V, even under the harshest conditions tested (50 °C and pH 2) the peptide did not release into solution after 24 h. Quantitative depth profiling detected nitrogen to depths of up to 2.8 μm, indicating the presence of nisin in the cracks. A simple test of the antibacterial performance of these surfaces against Listeria monocytogenes has been demonstrated. •Nisin can be adsorbed on cracked and uncracked stainless steel and titanium alloy surfaces by using physisorption.•Acidic pH is the most influential factor on the desorption of nisin from uncracked stainless steel surfaces.•Low pH and high temperature leads to corrosion of the cracked stainless steel, releasing all nisin from the crack walls.•Adhesion of nisin to the cracks walls of the titanium alloy is higher compared to stainless steel.