Bactericidal surfaces: An emerging 21st-century ultra-precision manufacturing and materials puzzle

Progress made by materials scientists in recent years has greatly helped the field of ultra-precision manufacturing. Ranging from healthcare to electronics components, phenomena such as twinning, dislocation nucleation and high-pressure phase transformation have helped to exploit plasticity across a wide range of metallic and semiconductor materials. One current problem at the forefront of the healthcare sector that can benefit from these advances is that of bacterial infections in implanted prosthetic devices. The treatment of implant infections is often complicated by the growth of bacterial biofilms on implant surfaces, which form a barrier that effectively protects the infecting organisms from host immune defences and exogenous antibiotics. Further surgery is usually required to disrupt the biofilm, or to remove the implant altogether to permit antibiotics to clear the infection, incurring considerable cost and healthcare burdens. In this review, we focus on elucidating aspects of bactericidal surfaces inspired by the biological world to inform the design of implant surface treatments that will suppress bacterial colonization. Alongside manufacturing and materials related challenges, the review identifies the most promising natural bactericidal surfaces and provides representative models of their structure, highlighting the importance of the critical slope presented by these surfaces. The scalable production of these complex hierarchical structures on freeform metallic implant surfaces has remained a scientific challenge to date and as identified by this review, is one of the many 21st Century puzzles to be addressed by the field of applied physics.

The work was supported by the ERASMUSþ program of the
European Union (KA103). The Surface Technologies Research Group (Mondragon University, Faculty of Engineering) gratefully acknowledges the financial support given by the Red Guipuzcoana de Ciencia Tecnologıa e Innovacion 2018 program through the project ASEFI (Orden Foral Numero 218/2018). This project has
received funding from the European Union’s Horizon 2020
research and innovation program under Grant Agreement No. 814494 (project “i-TRIBOMAT”) and Grant Agreement No. 665337 (project “LiNaBioFluid”). The contribution of J.C. (Eurecat) has been financed by the Ministry of the Economy, Industry and Competitiveness of Spain under the project BIOPLASMA (MAT2015-67103-C4-4-R) and DEMANDING (PGC2018-096855-B-C42).
S.G. gratefully acknowledges the financial support provided by the UKRI via Grants Nos. EP/L016567/1, EP/S013652/1, EP/S036180/1, EP/T001100/1, and EP/T024607/1; Royal Academy of Engineering via Grants No. IAPP18-19\295, TSP1332, and EXPP2021\1\277; EURAMET EMPIR A185 (2018); EU Cost Action (CA15102, CA18125, CA18224, and CA16235); and Newton Fellowship award from the Royal Society (NIF\R1\191571) as well as the European Regional Development Funds (ERDF) sponsored A2i project at LSBU that has catalyzed several industrial
partnerships.
The work used Isambard Bristol, UK, supercomputing service accessed by a Resource Allocation Panel (RAP) grant as well as ARCHER resources.