The surfaces of implantable medical devices can over time be colonized by bacteria, creating a risk for dangerous infections. Antibiofilm coatings, e.g., based on silver, could be useful to prevent the adhesion of bacteria to the surfaces of such medical devices. However, this approach has some challenges. For example, silver can also be toxic to human cells and the continuous release of small concentrations of silver ions over long periods can be challenging to achieve.
Dirk Lange, Jayachandran N. Kizhakkedathu, University of British Columbia, Vancouver, Canada, and colleagues have developed silver-based, film-forming antibacterial assemblies that form durable, biocompatible antibiofilm surfaces with long-term activity. The team used a combination of a low-molecular-weight amine-containing polymer (LAP) and an ultrahigh-molecular-weight antifouling polymer (UAP), together with silver nitrate and a catecholamine that reduces the silver salt to nanoparticles.
The most promising composition was found via semi-high-throughput screenings. The best properties were observed for a coating made from polyethylenimine (PEI) as the LAP component, poly(N,N-dimethylacrylamide) (PDMA) as the UAP, polydopamine (PDA) as the catecholamine component, and silver nitrate. This mixture gave stable, silver-nanoparticle-containing assemblies that gradually release silver ions. The coating can be applied via dipping or spraying. Flat substrates can also be coated via a solution-skinning method, in which the substrate was placed face-down on a coating layer formed at the interface of air and the coating precursor solution.
In tests in bacterial cultures, the developed coating effectively kept several types of bacteria, e.g., P. aeruginosa, E. coli, and methicillin-resistant S. aureus (MRSA) from growing on the coated surface. This is due to the antiadhesion properties of the coating and the antimicrobial effect of the slowly released silver ions. To test the coating’s effectiveness in vivo, the team coated a titanium coil that was placed under the skin of rats. They found that implants with the coating were biocompatible and had significantly fewer bacteria on their surface than uncoated controls after one week. The coating could be useful in different types of medical devices and implants to prevent bacterial infection over the long term.
- Durable Surfaces from Film-Forming Silver Assemblies for Long-Term Zero Bacterial Adhesion without Toxicity,
Hossein Yazdani-Ahmadabadi, Demian F. Felix, Kai Yu, Han H. Yeh, Haiming D. Luo, Sara Khoddami, Lily E. Takeuchi, Amal Alzahrani, Srinivas Abbina, Yan Mei, Ladan Fazli, Dana Grecov, Dirk Lange, Jayachandran N. Kizhakkedathu,
ACS Cent. Sci. 2022.
https://doi.org/10.1021/acscentsci.1c01556
