Silver has a long history of being used as an antibacterial material, and is viewed with renewed interest today for applications such as wound healing. Recently, a team of scientists from the University of Science and Technology of China (USTC) has studied the interaction of nanoparticles on graphene oxide sheet with E. coli and observed behaviour that could lead to the synthesis and assembly of innovative and highly active antibacterial materials.

To prepare the assembly, the team used protein-coated graphene oxide as a template to guide the arrangement of Au@Ag core-shell nanoparticles into a two-dimensional (2D) array. In the case of such a nano-hybrid, the researchers observed significantly increased bacteria-killing ability compared with individual nanoparticles and silver ions.

The group believes that this activity enhancement could be related to a "group-attacking" effect of the assembled nanoparticles. Mechanistic studies revealed strong adhesion of the 2D Au@Ag nano-assembly on the cell surface, which caused an aggregation and cellular lysis of the bacteria. During this process, the increased local concentration of silver around a bacterium and the "polyvalent" nanoparticle-bacterium interaction were both critical.

Next, the scientists plan to study the composition-, size-, and shape-related antibacterial behaviors of self-assembled materials, and to evaluate the antibacterial activity of samples against more bacterial species, including gram-positive ones.

Additional details can be found in the journal Nanotechnology 24 205102

Further reading

Photothermal effect of gold nanorod cluster disinfects biofilm (Jul 2013)
Antibacterial coatings: taking lessons from nature (Dec 2012)