Plasma strategy boosts antibacterial efficacy of silica-based materials

Researchers Ni Guohua and Associate Researcher Sun Hongmei from the Institute of Plasma Physics, together with Associate Professor Wang Dong from Anhui Medical University, have developed a novel two-step plasma strategy to modify mesoporous silica-supported silver nanoparticles, enabling them to achieve strong antibacterial activity and accelerated wound healing.

Their findings were published in the Chemical Engineering Journal.

Mesoporous silica-supported silver nanoparticles (Ag/MSNs) show great potential for wound healing due to their strong antibacterial activity and low toxicity. However, their negatively charged surface repels bacteria, lowering antibacterial efficiency. Traditional ways to add positive amino groups often suffer from uneven distribution, poor stability, and complex procedures.

In this study, the team developed a two-step plasma strategy to create surface-functionalized silver/mesoporous silica composites (Ag/MSNs-R). In this method, silver nanoparticles were first deposited on MSNs through hydrogen plasma reduction. Then, a mixed plasma of CF₄ and NH₃ was applied to graft an amine-fluorocarbon polymer layer onto the surface.

As a result, silver nanoparticles with an average diameter of about 6.25 nm were uniformly distributed, and the modified materials acquired a positive surface charge, enhancing their interaction with bacterial membranes.

Laboratory tests showed that Ag/MSNs-R reduced bacterial viability by more than 98% against both Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative), achieving antibacterial effects several times stronger than unmodified Ag/MSNs.

Animal studies further confirmed that the modified materials effectively suppressed E. coli infections, alleviated inflammation, and promoted faster wound healing through the Arginase-1 signaling pathway.

This work not only provides a new approach for grafting functional groups onto silica, but also opens new possibilities for designing safer and more effective antibacterial materials for medical use.