gms | German Medical Science

Objectives: The development of anti-infective implants for prevention of implant-associated infections is an important challenge in biomaterials research. In addition to multi-resistant bacteria, the number of mycoses, often caused by Candida species, is also increasing, which contributes significantly to the morbidity/mortality of surgical patients.

One promising strategy to reduce the risk of implant-related infections is the inhibition of initial implant colonization by supportive anti-infective agents such as silver. However, smart implant materials should not only ensure effective pathogen killing, but also avoid long-lasting toxic effects on human tissue, which requires low silver amount and efficient time-limited silver ion release localized at the implant site. These requirements can be met by crosslinking of nanotechnology and the sacrificial anode principle - by combining nanosilver with nanoplatinum the efficiency of silver ion release is significantly increased based on sacrificial anode effect, while the amount of metal required for the anti-infective activity is highly reduced. We have already demonstrated the significantly increased antibacterial efficacy of such sacrificial anodes compared to pure silver (Breisch et al., 2019; Abuayyash et al., 2020). Here, the antimycotic activity of these surfaces was tested.

Methods: Nanostructured silver-platinum surfaces (Ag/Pt nanopatches) were generated by short-time magnetron sputtering on titanium specimen. Microstructure analyses were performed by HR-TEM and EDX mapping. Antifungal activity was analyzed by Candida albicans colonization of the surfaces using droplet-based assay, fluorescence microscopy and agar plate assay. Silver dissolution was determined by voltammetric measurements.

Results and conclusion: TEM/EDX analyses showed that short sputter times (20-60s) resulted in island-like growth of Ag and Pt, producing structures on the order of few nanometers. The antimycotic activity of these Ag/Pt nanopatches against Candida albicans was significantly higher compared to pure Ag nanopatches. Voltammetric analysis revealed an underlying sacrificial anode effect, which induced increased Ag ion release in Ag/Pt nanopatches due to the presence of Pt.

Thus, using short-time magnetron sputtering it was possible to generate nanostructured Ag/Pt surfaces with effective antibacterial as well as antimycotic activity based on the sacrificial anode principle. Advantages of this coating are the use of only very small amounts of precious metal and a self-limiting active phase that prevents long-lasting tissue damage.