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Carbon nanotubes have been emerging as promising material to be used in drug delivery. Single walled carbon nanotubes (SWNTs) are allotropes of carbon with a single layer of carbon atoms arranged hexagonally and rolled into a seamless cylinder about 1 nm in diameter. SWNTs vary in length and have a high membrane penetrability and the ability to be easily functionalized to carry chemical compounds. SWNTs functionalized with the antibiotic tetracycline are being used to overcome tetracycline resistance in Escherichia coli. Studies have shown that the antibiotic tetracycline kills E. coli cells at very low concentrations (μg/mL). The E. coli strain DH5α is being examined. Over long periods of exposure to tetracycline, DH5α E. coli develops the resistance plasmid PBR322. The plasmid includes a gene that codes for an efflux pump resistance mechanism. It has previously been observed that SWNTs functionalized with tetracycline can be used to deliver tetracycline to the resistant E. coli and effectively kill the cells by blocking the efflux pump from pumping out the tetracycline. In past experiments, tetracycline functionalized SWNTs have been able to inhibit growth of DH5α/PBR322 at high concentrations (500 μg/mL). Adaptations in the protocol have been made in order to increase the effectiveness of the drug delivery at lower concentrations (<100 >μg/mL). These adaptations include acid cutting the SWNTs, using longer periods of sonication, and functionalizing the SWNTs with short chain (3000 M.W.) polyethylene glycol to increase the solubility of SWNTs in the hopes of increasing tetracycline attachment during functionalization.
Force, Madison, "The Use of Tetracycline-Functionalized Single-Walled Carbon Nanotubes to Overcome Tetracycline Resistance in Escherichia coli" (2015). Chemistry Summer Fellows. Paper 3.