Fighting Bacteria with ultrafast LAser fabrication of sharp nanoSTructured surfaces – BLAST

Antibiotic resistance is one of the most serious public health concerns, with projections predicting over 10 million deaths in the next 20 years. Non-pharmacological methods are essential to reduce the risk of bacterial colonization on surfaces associated with medical procedures. The BLAST project is focused on developing antibacterial surfaces, particularly for titanium implants, to prevent infections while ensuring biocompatibility and successful tissue integration.
Recently, antibacterial surfaces containing 'nanopeaks' capable of bactericidal action have been discovered in nature, particularly on insect wings. Ultrafast laser irradiation is a well-established method for generating nanostructures on metallic surfaces. The laser/matter interaction leads to the formation of a wide variety of nano-structures whose shape and distribution depend on laser process parameters. This year, the Hubert Curien laboratory published original results concerning the use of a femtosecond laser to transform a metallic surface into a "forest of nano-peaks" with the highest aspect ratio ever achieved (100 nm high and 20 nm wide). The method used lies in an unexplored scientific field where the coupling of light and the hydrodynamic effects act in a coherent and synergistic way at the nanometric scale, allowing the creation of biomimetic self-organized metastructures. Clarifying the link between achieving the desired nanostructures and the precise laser beam engineering processes remains a major challenge. Artificial intelligence will be used as an optimization tool.
Based on these promising results, the BLAST project aims to generate a diverse range of self-organized nanopatterns that are both reproducible and possess features entirely controllable through laser parameters (morphology, density, periodicity, aspect ratio…) on titanium alloy. Thanks to the development of advanced analysis of surfaces, the study aims to thoroughly understand the influence of biologically relevant topographical nano-features. It provides precise knowledge about the effectiveness of nanostructures against different types of bacteria (antibiotic-resistant bacteria, highly virulent bacteria, GRAM+ or GRAM-) and their performance in terms of bio-integration in biological tissues. An original aspect of the BLAST project resides in the fact that we assess various nanopatterns for their potential medical applications. Concerning medical implants, we propose diverse applications based on the dual nature of the surface: a surface exhibiting excellent antibacterial properties along with good biocompatibility and enhanced biological activity will be suitable for permanent implant usage (such as orthopedic or dental implants), whereas a surface demonstrating good compatibility but limiting cell adhesion will be recommended for screws and plates (temporary orthopedic fixations in cases of fractures).
Ultimately, the BLAST project aims to contribute to the development of innovative solutions to combat antibiotic resistance and improve the performance of medical implants through the biomimetic nanostructuring of surfaces by laser. In cases where the surface topography exhibits only antibacterial properties, the project explores additional applications to maximize its impact, particularly for surfaces intended for everyday use. Thus, the project provides technical guidelines for femtosecond laser surface nano-engineering and pave the way for numerous applications in the medical field.
The BLAST project is based on the complementary expertise of three laboratories: the Hubert Curien Laboratory, specializing in femtosecond laser structuring; the LTDS laboratory, dedicated to surface characterization and the study of cell/surface interactions; and the SAINBIOSE laboratory, which focuses on evaluating antibacterial performance and bio-integration. With a duration of 48 months, the project will involve a PhD student, two postdoctoral researchers, and two Master's students.