Safe and non-fouling reactive antibacterial agents on cotton fabrics

Abstract

The study focuses on the synthesis of reactive sulfobetaine antibacterial agents which are used in cotton fabrics to solve the problems in bacterial multi-drug resistance, bacterial contamination and washing durability. Generally, bacteria adhering on cotton fabrics surfaces form biofilms, which are difficult removed. The biofilms provide ideal shelters and allow them to metabolize safely within the environment. Therefore, it is significant and essential for researchers to develop new and effective antimicrobial agents that kill bacteria or prevent bacterial adhesion and biofilm formation on the fabric surfaces. This thesis presented three reactive antibacterial agents and the related characterization on structure, antibacterial property, physical property, non-fouling property, washing durability and cytotoxicity. 1. Pyridine sulfobetaine: The obtained pyridine sulfobetaine structure was confirmed by ¹H-NMR spectra and ESI-MS. The thermostability and antibacterial activity were characterized by TGA and bacterial growth kinetics. At a lower concentration, para-pyridine sulfobetaine showed excellent antibacterial activities when acted on gram-negative E.coli and gram-positive S.aureus, with the MIC of 8.36 μmol/ml and 10.45 μmol/ml against E.coli and S.aureus respectively. When applied it to cotton fabric with a pad-dry-cure finishing, the antibacterial rate of the modified cotton fabric could reach 99.90% or higher against both gram-negative E.coli and gram-positive S.aureus. In addition, compared to the raw cotton fabric, the modified cotton fabric exhibited slightly reduced air permeability and significantly improved hydrophilicity. The as-modified cotton fabric is more skin compatible confirmed by skin stimulation test and non-toxic. Therefore para-pyridine sulfobetaine could be a good alternative for medical fabric and other relevant applications. 2. s-triazine sulfobetaine: The s-triazine sulfobetaine was synthesized via cyanuric chloride mono-substitution reaction. Its structure was confirmed by ¹H-NMR and ¹³C NMR spectra. The MIC was quantitatively determined by measuring bacterial growth kinetics in liquid media. The MIC of s-triazine sulfobetaine against S.aureus and E.coli were 2 mg/ml and more than 6 mg/ml respectively. 3. BTCA-betaine: BTCA was used as cross-linking to give cotton fabric durable washing durability. The concentration of BTCA are 5% and 8%. The air permeability, tearing strength, antibacterial activity, washing durability, non-fouling property and cytotoxicity were evaluated according to the related standard respectively. The air permeability and tearing strength of modified cotton fabric reduced. The modified cotton fabric showed excellent antibacterial activity, washing durability and non-fouling property. Via SEM and fluorescence microscope observation, the modified cotton fabric showed no cytotoxicity on fibroblast. It indicates that the modified cotton fabric is biocompatible and safe.