Abstract
BackgroundRemoval of pathogens from water is one way to prevent waterborne illness. In this paper, we developed dual functional carbon nanotube (CNT) modified filters for bacterial capture and inactivation, utilizing multi-walled CNTs (MWCNTs) to coat on commercially available filters and making use of the exceptional adsorption property of CNTs to adsorb a natural antimicrobial peptide-nisin on it. Two types of MWCNTs with different outer layer diameters were used (MWCNTs1: <8 nm in diameter; MWCNTs2: 10–20 nm in diameter).ResultsThe thickness of MWCNT layers, surface morphology, and surface hydrophobicity of both types of MWCNT coated filters were characterized. The MWCNT coating on filters significantly increased the surface hydrophobicity. The absorption of nisin and the capture of bacterial pathogens were correlated with increased surface hydrophobicity. The MWCNTs1 and MWCNTs2 filters with 1.5 mg MWCNTs loading captured 2.44 and 3.88 log of cells, respectively, from aqueous solutions containing a total of ~106 CFU/mL cells. Nisin deposit at the amount of 0.5 mg on the surfaces of MWCNT filters significantly reduced the viability of captured B. anthracis cells by 95.71–97.19 %, and inhibited the metabolic activities of the captured cells by approximately 98.3 %.ConclusionsThe results demonstrated that the MWCNT-nisin filters achieved dual functions in bacterial pathogen capture and inhibition in one single filtration step, which is potentially applicable in removing undesired microorganisms from water sources and inhibiting captured Gram positive bacteria activities.
Highlights
Removal of pathogens from water is one way to prevent waterborne illness
This study demonstrated that multi-walled carbon nanotube (CNT) (MWCNTs)-nisin coated filters possess dual functions in capturing and inactivating bacterial pathogens
Based on the tests in this study, with 1.5 mg MWCNTs loading, the MWCNT1filters and MWCNT2 coated filters captured 2.43 and 3.88 log of B. anthracis cells from aqueous solutions containing a total of 106 colony forming units per milliliter (CFU/mL) cells, respectively
Summary
Removal of pathogens from water is one way to prevent waterborne illness. In this paper, we developed dual functional carbon nanotube (CNT) modified filters for bacterial capture and inactivation, utilizing multi-walled CNTs (MWCNTs) to coat on commercially available filters and making use of the exceptional adsorption property of CNTs to adsorb a natural antimicrobial peptide-nisin on it. Effective control of pathogenic microorganism contamination in water can be a significant contribution to ensure water quality and to prevent waterborne infectious diseases throughout the world. One commonly used category of methods relies on the use of various antimicrobial chemical treatments, such as adding gaseous chlorine (Cl2), liquid sodium hypochlorite, chloramine, chlorine dioxide, chloramines, hydrogen peroxide, or bromine into water. These chemicals are effective in inactivating pathogens, but at the same time pose risks in environmental safety and public health. The use of lower concentrations of the antimicrobial agents may minimize such risks, but in many cases, low concentrations definitely compromise the antimicrobial effect [6].
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