Comparison of Attachment and Antibacterial Activity of Covalent and Noncovalent Lysozyme-Functionalized Single-Walled Carbon Nanotubes

Matthew M Noor; Joyanta Goswami; Virginia A Davis

doi:10.1021/acsomega.9b03387

Comparison of Attachment and Antibacterial Activity of Covalent and Noncovalent Lysozyme-Functionalized Single-Walled Carbon Nanotubes

ACS Omega. 2020 Jan 27;5(5):2254-2259. doi: 10.1021/acsomega.9b03387. eCollection 2020 Feb 11.

Authors

Matthew M Noor¹, Joyanta Goswami¹, Virginia A Davis¹

Affiliation

¹ Department of Chemical Engineering, Auburn University, 212 Ross Hal, Auburn, Alabama 36849, United States.

Abstract

Carbon nanotube-lysozyme (LSZ) conjugates provide an attractive combination of high strength and antimicrobial activity. However, there has not been a direct comparison of the covalent and noncovalent methods for creating them. In this work, single-walled carbon nanotubes (SWNT) were functionalized with LSZ using both noncovalent adsorption and covalent attachment via N-ethyl-N-(3-dimethylamino-propyl) carbodiimide hydrochloride-N-hydroxysuccinimide (EDC-NHS) chemistry. The amount of attached lysozyme, dispersion stability, and antimicrobial activity was compared. In addition, the mechanical properties of LSZ-SWNT in poly(vinyl alcohol) (PVA) composite films were investigated. Dispersions of covalently bound LSZ-SWNT had better dispersion stability. This was attributed to covalent functionalization enabling sustained SWNT dispersion at a lower LSZ/SWNT ratio. The covalently bound LSZ-SWNT also exhibited a lower initial rate of antibacterial response but were active over a longer time scale. Composite films made from LSZ-SWNT maintained similar activity as the corresponding dispersions. However, the noncovalent LSZ-SWNT films were stronger and more hydrolytically stable than those made from covalent LSZ-SWNT.