Journal
APPLIED SURFACE SCIENCE
Volume 356, Issue -, Pages 325-332Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.apsusc.2015.08.087
Keywords
Anti-bacterial; Polyurea; Polyethyleneimine; Quaternary ammonium; X-ray photoelectron spectroscopy; Fluorescein
Categories
Funding
- UMCG
Ask authors/readers for more resources
Coatings of immobilized-quaternary-ammonium-ions (QUAT) uniquely kill adhering bacteria upon contact. QUAT-coatings require a minimal cationic-charge surface density for effective contact-killing of adhering bacteria of around 10(14) cm(-2). Quaternization of nitrogen is generally achieved through alkylation. Here, we investigate the contribution of additional alkylation with methyl-iodide to the cationic-charge density of hexyl-bromide alkylated, hyperbranched polyurea-polyethyleneimine coatings measuring charge density with fluorescein staining. X-ray-photoelectron-spectroscopy was used to determine the at.% alkylated-nitrogen. Also streaming potentials, water contact-angles and bacterial contact-killing were measured. Cationic-charge density increased with methyl-iodide alkylation times up to 18 h, accompanied by an increase in the at.% alkylated-nitrogen. Zeta-potentials became more negative upon alkylation as a result of shielding of cationiccharges by hydrophobic alkyl-chains. Contact-killing of Gram-positive Staphylococci only occurred when the cationic-charge density exceeded 10(16) cm(-2) and was carried by alkylated-nitrogen (electron-binding energy 401.3 eV). Gram-negative Escherichia coli was not killed upon contact with the coatings. There with this study reveals that cationic-charge density is neither appropriate nor sufficient to determine the ability of QUAT-coatings to kill adhering bacteria. Alternatively, the at.% of alkylated-nitrogen at 401.3 eV is proposed, as it reflects both cationic-charge and its carrier. The at.% N-401.3 eV should be above 0.45 at.% for Gram-positive bacterial contact-killing. (C) 2015 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available