Biocidal efficacy, biofilm-controlling function, and controlled release effect of chloromelamine-based bioresponsive fibrous materials

Abstract

In this study, 2-amino-4-chloro-6-hydroxy-s-triazine (ACHT) was synthesized through controlled hydrolysis of 2-amino-4,6-dichloro-s-triazine (ADCT). A simple paddry-cure approach was employed to immobilize ACHT onto cellulosic fibrous materials. After treatment with diluted chlorine bleach, the covalently bound ACHT moieties were transformed into chloromelamines. The structures of the samples were fully characterized with NMR, UV/VIS, DSC, TG, iodometric titration and elemental analyses. The chloromelamine-based fibrous materials provided potent, durable, and rechargeable biocidal functions against bacteria (including multi-drug resistant species), yeasts, viruses, and bacterial spores. SEM studies demonstrated that the new fibrous materials could effectively prevent the formation of biofilms, and controlled release investigations in vitro suggested that the biocidal activities were bioresponsive. Biocidal mechanisms of the chloromelamine-based fibrous materials were further discussed.

Antibacterial Modification of Microcrystalline Cellulose by Grafting Copolymerization

“…The Tmax of chlorinated MAM-g-MCC occurred at 334 °C, which was lower than that of pristine MCC (Tmax 351 °C) and MAM-g-MCC (Tmax 341 °C). The decomposition of the N-Cl bond at 180 °C most likely accelerated the thermal decomposition of the cellulose backbone, leading to weight loss from chlorinated MAM-g-MCC at relatively low temperatures (Chen et al 2007). …”

“…This efficient antibacterial property was due to the oxidative chlorine formed by the chlorination of the N-halamine precursor. The oxidative chlorine was transferred to the cell membrane, reacted with receptors in the cells, and inactivated the microorganisms (Chen et al 2007). …”

“…After 60 min, chlorinated MAM-g-MCC samples were filtered and washed with excess distilled water, filtered again, and dried at 45 °C to remove free oxidative chlorine absorbed on the MCC surface. The chlorine loadings on the chlorinated MAM-g-MCC samples were determined via the iodometric/thiosulfate titration method and calculated according to the following equation (Chen et al 2007 …”

“…After halogenation, the nitrogen-hydrogen groups can be oxidized to form nitrogen-halogen groups, which can transfer oxidative halogens to microorganisms' surfaces, destroying their cellular systems and killing the cells (Chen and Sun 2006;Kou et al 2009). Some researchers have proposed that intact chloromelamine moieties may also have biocidal effects, inhibiting the growth of organisms if the free chlorines present in wet environments are not sufficient to inactivate tougher microorganisms (Chen et al 2007). After organisms are inactivated, the oxidizing nitrogen-halogen groups are reduced to nitrogen-hydrogen groups that can be rehalogenated by sodium hypochlorite; the materials modified by N-halamine compounds have long-term antibacterial properties (Sun amd Sun 2001;Zhu et al 2012).…”

Biocidal polymers (II): Determination of biological activity of novel N-halamine biocidal polymers and evaluation for use in water filters

“…However, some biocidal activity is retained in the presence of the quenching agent which suggests some biocidal effect depends on the action of the halogenated polymer itself and proceeds through contact between bacteria and polymer particles. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] This dual mechanism of killing (contact + release of halogen species) is currently under investigation and will be reported in due course. In addition to these two expected modes of action there is another possibility: killing the bacteria by changing the nature of the environment around the bacterial cells by exchanging the halogen between the halogenated polymer and proteins in medium.…”