title: Mitigation of bactericidal effect of carbon nanotubes by cell entrapment.
abstract: This study investigated the effects of the alginate and polyvinyl alcohol (PVA) entrapment on the viability of Escherichia coli cells exposed to single wall carbon nanotubes (SWCNTs) with a diameter of 1-2nm. Viability was examined using a galactosidase enzyme assay, LIVE/DEAD BacLight assay, and total ribonucleic acid quantity. Variables studied included SWCNT concentration (5, 10, 20, 50, 100, 200, 500, and 1000μg/ml), SWCNT length (0.5-2μm for short SWCNTs and 5-30μm for long SWCNTs), and initial bacterial concentration (6.5 log10 CFU and 9 log10 CFU per test). Results showed that both alginate and PVA entrapments mitigate the bactericidal effect of SWCNTs. At the highest SWCNT concentration tested (1000μg/ml), the viability of the cells relative to controls (systems with only E. coli, no SWCNTs), was 0-60% for free cells and 60-90% for alginate and PVA entrapped cells. The bactericidal effect depended on SWCNT type and concentration, and bacterial concentration. In general, long SWCNTs (5-30μm) caused significantly greater reductions in the viability of entrapped cells than the short SWCNTs except for the two highest SWCNT concentrations studied, 500 and 1000μg/ml. Microscopy showed that the entrapment matrices prevented SWCNTs from entering the beads. This study shows that bacterial entrapment is effective at limiting the bactericidal effect of SWCNTs.
authors.affiliation: Environmental and Conservation Sciences Program, North Dakota State University, Fargo, ND 58108, USA; Biology Department, Da Lat University, Da Lat, Vietnam.
authors.forename: Tu Thi Anh
authors.initials: TTA
authors.lastname: Le
authors.affiliation: Veterinary and Microbiological Sciences Department, North Dakota State University, Fargo, ND 58108, USA.
authors.forename: John
authors.initials: J
authors.lastname: McEvoy
authors.affiliation: Civil and Environmental Engineering Department, North Dakota State University, Fargo, ND 58108, USA. Electronic address: eakalak.khan@ndsu.edu.
authors.forename: Eakalak
authors.initials: E
authors.lastname: Khan
mesh_terms: D000464:Alginates / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000502:physiology; D005782:Gels; D020723:Glucuronic Acid / Q000494:pharmacology; D006603:Hexuronic Acids / Q000494:pharmacology; D037742:Nanotubes, Carbon; D011142:Polyvinyl Alcohol / Q000494:pharmacology*
chemical_list: D000464:Alginates; D000900:Anti-Bacterial Agents; D005782:Gels; D006603:Hexuronic Acids; D037742:Nanotubes, Carbon; D020723:Glucuronic Acid; D011142:Polyvinyl Alcohol
keywords: Adverse impact; Bacteria; Carbon nanotubes; Cell entrapment; Cell viability