Characterization of Silver-coated Carbon Nanotubes Dispersed in a Specifically Formulated Dispersant - NanoSperse AQ®

摘要

Silver-coated carbon nanotubes (AgCNTs) are well documented for their antibacterial properties. However, aqueous dispersions of AgCNTs could be less effective against bacteria due to their tendency to agglomerate when re-suspended in water. This may be controlled by adopting different dispersion techniques for AgCNTs such as using a specifically formulated dispersant solution. In this study we have characterized AgCNTs dispersed in Nanosperse AQ® (dAgCNTs) from NanoLab Inc. and water dispersed AgCNTs (wAgCNTs), and compared then-bactericidal activity against Salmonella enterica serovar Typhimurium and Escherichia coli. AgCNTs were characterized using zeta potential and fourier transform infrared spectroscopy (FT-IR) analysis. dAgCNTs were homogenously dispersed as compared to wAgCNTs which formed agglomerates even after repeated sonication. The zeta potential value of dAgCNTs was -41.9mv compared to wAgCNTs (-30.7mv) indicating a higher degree of stability for dAgCNTs. FT-IR analysis of dAgCNTs showed the presence of additional peaks specific for dAgCNTs as compared to wAgCNTs. The minimum inhibitory concentrations (MIC) of dAgCNTs (31-15 μg/ml) were approximately three folds lower compared to wAgCNTs (100-62.5 μg /ml) against both Salmonella enterica serovar Typhimurium and Escherichia coli. Live/dead staining revealed that exposure to 12.5 μg /ml of dAgCNTs resulted in at least twice the number of dead bacteria as compared to exposure to similar concentrations of wAgCNTs. NanoSperse AQ® did not have any antibacterial effect by itself. Our results indicate that dispersion of AgCNTs using an appropriate dispersion technique may result in a relatively stable and homogenous solution of AgCNTs, thereby improving their antibacterial activity.