Implant infection, due to bacterial contamination, is a significant problem that represents one of the main causes of implant loss over time. In addition, the incidence of antibiotic resistance is steadily increasing, and alternative ways to fight or prevent infection have become the subject of biomedical research, and several surface modification and coating techniques have recently been developed for antibacterial applications.
In this work, three different molecules: alpha tocopherol, its water-soluble version alpha-tocopheryl phosphate, and a synthesized peptoid (GN-2-Npm9) were studied and chosen to create surfaces with antibacterial and anti-inflammatory properties.
Titanium Ti6Al4V alloy samples (ASTM B348, Gr5, Titanium Consulting and Trading, 10 mm diameter discs) were ground (up to 400 grit), then washed in acetone and deionized water. The discs were chemically treated to increase nanoscale roughness, to expose OH groups, and to make the surface more suitable for the grafting. The treated samples were irradiated with UV light to reduce carbon contamination,.
The modifications of titanium surfaces are explored as a coating or through functionalization and a procedure for proper characterization of this substrates was investigated. Physical and chemical characterization was performed through specific measurement techniques such as FTIR-ATR, Z-potential, reflectance spectroscopy, contact angle and release tests.
Biological characterization was performed through cellular and antibacterial assays.
Results and discussion:
The modified surfaces are compared through FTIR-ATR and reflectance spectroscopy, z-Potential titration curves, contact angle measurements, release test, and tape test. The aim is to verify the effective presence of the molecules on the surfaces, the chemical stability over time, mechanical adhesion properties and hydrophobic behaviour for all three grafted molecules. The biological outcome is tested by the cellular and antibacterial tests. According to the results, both grafting and coating can be effectively performed and the biological response can be modulated from anti-adhesive to tissue integration by properly selecting the grafted biomolecules according to the final application (temporary or permanent implants). The surfaces show interesting antibacterial and anti-inflammatory properties.
This work highlights a promising new application of these biomolecules as possible candidates for bone implant surfaces that reduce the risk of an excessive pro-inflammatory response, the risk of implant-associated infections, and allow for the disincentive of antibiotic use associated with the post-operative period.