Remarkably Improvement in Antibacterial Activity of Carbon Nanotubes by Hybridizing with Silver Nanodots

In view of their super capacity of adsorbing microbial, the carbon nanotubes (CNTs) were used as the carriers for in situ synthesizing well-dispersed and small-sized silver nanodots (AgND), to prepare a new type of antibacterial agent with remarkably improved activity. Polyethyleneimine (PEI) was introduced as a linkage for guaranteeing the as-generated AgND to be anchored onto the CNTs and to prevent them from agglomeration. The obtained hybridizing materials were characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy, and the results showed that the AgND with an average size of 2.6 nm were uniformly loaded on surfaces of CNTs. There existed special interactions between silver atoms and CNTs. The antibacterial activities of the as-prepared hybrids against Escherichia coli were evaluated by disk diffusion assay method and minimal inhibitory concentration measurements. The results showed that the as-prepared hybrids displayed a remarkable improvement in antibacterial activity as compared to CNTs, acidified-CNTs and even the identical silver amount of AgNO₃ solution, which was mainly attributed to the small size of AgND and the hybridizing effect between AgND and CNTs.