Enhancing Staphylococcus aureus sterilization of stainless steel by the synergistic effect of surface structure and physical washing

Surface antibacterial properties enhanced through engineered textures and surface roughness: A review

The spread of bacteria through contaminated surfaces is a major issue in healthcare, food industry, and other economic sectors. The widespread use of antibiotics is not a sustainable solution in the long term due to the development of antibiotic resistance. Therefore, surfaces with antibacterial properties have the potential to be a disruptive approach to combat microbial contamination. Different methods and approaches have been studied to impart or enhance antibacterial properties on surfaces. The surface roughness and texture are inherent parameters that significantly impact the antibacterial properties of a surface. They are also directly related to the previously employed machining and treatment methods. This review article discusses the correlation between surface roughness and antibacterial properties is presented and discussed. It begins with an introduction to the concepts of surface roughness and texture, followed by a description of the most commonly utilized machining methods and surface. A thorough analysis of bacterial adhesion and growth is then presented. Finally, the most recent studies in this research area are comprehensively reviewed. The studies are sorted and classified based on the utilized machining and treatment methods, which are divided into mechanical processes, surface treatments and coatings. Through the systematic review and record of the recent advances, the authors aim to assist and promote further research in this very promising and extremely important direction, by providing a systematic review of recent advances.

A Small-scale Washing Test That Reproduces the Mechanical Forces Occurring Inside a Commercial Washing Machine

A small-scale washing test model was proposed to reproduce the mechanical forces occurring inside a household washing machine in Japan. Washing tests were conducted using household washing machines, a tergotometer, and four types of small-scale washing test models using JIS-designated artificially soiled fabric. As a result of conducting washing tests in 10 households during winter and summer, we determined that the mechanical force of the washing machine was equivalent to 90-100 rpm agitation by a tergotometer. Similar detergency was obtained by rotating a 50 mL centrifuge tube with a tube rotator. Then, a centrifuge tube containing 35 mL of detergent solution, ten 1/4-inch stainless steel balls, and three 20 × 20 mm soiled fabrics was rotated at 50 rpm. Probability density functional theory analysis did not identify any kinetic problems, which means that the properties of the applied mechanical forces are similar to those occurring in the tergotometer and tube rotator test.

Structure-Element Surface Modification Strategy Enhances the Antibacterial Performance of Zr-BMGs

Zirconium-based metallic glasses (Zr-BMGs) have attracted tremendous attention in healthcare fields, especially in the design of surgical tools and orthopedic implants, due to their unique amorphous structure; however, the application of Zr-BMG-based medical devices is hindered by bacterial contamination. Here, a structure-element strategy is proposed to improve the antibacterial performance of Zr-BMGs by surface laser nanostructuring and silver nanoparticle (AgNP) deposition. The laser nanostructuring process generates a disordered nanoparticle structure (NP) and laser-induced periodic surface structure (LIPSS) to decrease the surface bacterial adhesion and increase the internal antimicrobial ion release. Moreover, after Ag deposition and hydrogen peroxide (H₂O₂) treatment, the antibacterial adhesion ability of the Zr-BMG surface can be further improved without any influence on the crystallization of Zr-BMGs and the release of antibacterial copper/nickel (Cu/Ni). The antibacterial effect of the LIPSS and the NP surfaces presents over 90% bacterial killing ratio, which is superior to that of the naked Zr-BMGs with less than 60% bacterial killing ratio. In vitro and in vivo tests show that the Ag-deposited and H₂O₂-treated LIPSS surfaces exhibit an optimal balance between the antibacterial property and the biocompatibility compared with the polished, NP structured or LIPSS structured surfaces. It is assumed that such structure-element surface modification strategy can improve the antibacterial activity of metal-containing surgical tools and orthopedic implants, improving the success rate of medical treatment.

Antibacterial Performance of Zr-BMG, Stainless Steel, and Titanium Alloy with Laser-Induced Periodic Surface Structures

A laser-induced periodic surface structure (LIPSS) was shown to have antibacterial adhesion properties in previous research. In this study, the antibacterial performance of LIPSS on traditional biometals (stainless steel and titanium alloy) and a potential biometal (zirconium-based bulk metallic glass, Zr-BMG) was investigated. A femtosecond laser was used to fabricate LIPSS on the specimens. Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were used to examine the antibacterial behavior of the LIPSS samples. The bacterial adhesion force on each specimen was evaluated by an atomic force microscopy (AFM) cell probe. The results showed that the LIPSS on all three metal surfaces significantly lowered antibacterial adhesion compared to polished metal specimens. E. coli demonstrated a higher adhesion force but a lower surface adhesion rate compared to S. aureus. The Zr-BMG specimen with LIPSS has multiple antimicrobial mechanisms (physical antiadhesion and chemical elimination), while the traditional biometals (316L and TC4) mainly offer physical antiadhesion. Finally, an in vitro/vivo study showed that specimens with LIPSS surfaces did not significantly affect the biocompatibility of the specimens. This study reveals that the Zr-BMG specimen with femtosecond laser-processed LIPSS is an ideal choice for achieving an antibacterial surface.