Preparation of Hollow N-Chloramine-Functionalized Hemispherical Silica Particles with Enhanced Efficacy against Bacteria in the Presence of Organic Load: Synthesis, Characterization, and Antibacterial Activity

Abstract

The fabrication of highly effective antimicrobial materials is an important strategy for coping with the growing concern of bacterial resistance. In this study, N-chloramine-functionalized hollow hemispherical structures were designed and prepared to examine possible enhancement of antimicrobial performance. Antimicrobial testing was carried out on Gram-negative (Escherichia coli) and Gram-positive (Baccilus Cereus) bacteria in the presence and absence of biological medium. The efficacy of the hollow hemispherical particles functionalized with various N-chloramines in killing bacteria was compared among themselves with that of small organic molecules and spherical particles to investigate the effect of the surface charge, chemical structure, and shape of the particles. Results demonstrated that quaternary ammonium salt or amine functions in the chemical structure enhanced the antimicrobial activity of the particles and made the particles more effective than the small molecules in the presence of biological medium. The importance of particle shape in the killing tests was also confirmed.

Colloid particle formulations for antimicrobial applications

“…developed similar approach by using hemispherical silica shell particles produced by templating yeast cells with silica followed by their fragmentation, bleaching and surface functionalisation with N-chloramines. Antimicrobial testing was carried out on Gramnegative (E. coli) and Gram-positive (B. cereus) bacteria and confirmed their superior antimicrobial efficacy compared with small molecule antiseptic agents [121]. This approach opens a number of new avenues for building powerful selective biocides based on combinations of colloid antibodies and cell killing strategies based on nanoparticles which can be applied in new antibacterial therapies.…”

Quaternary Ammonium (QA) N‐Chloramines: Chemical Synthesis and Study on Structure Bactericidal Activity Relationship

“…NaOH as described in the literature. [11] Quaternization of 27 with methyl iodide smoothly produced precursor 14 a, which was then treated with ion exchange resin to give Cl À form counterpart together with other precursors of 15 a ∼ 20 a. Finally, N-chloramine 14 ∼ 20 was prepared successfully by chlorination with tert-butyl hypochlorite according to previous protocol.…”

“…It is worth to mention that aqueous dimethylamine was herein adopted instead of dimethylamine hydrochloride combined with equiv. NaOH as described in the literature [11] . Quaternization of 27 with methyl iodide smoothly produced precursor 14 a , which was then treated with ion exchange resin to give Cl − form counterpart together with other precursors of 15 a ∼ 20 a .…”

Magnetic solid phase extraction for chromatographic separation of carbamates

“…The sol‐gel formed silica layer significantly diminishes these two peaks. There are also three peaks, due to the formation of the silica layer, at 794, 955, and 1065 cm −1 , that correspond to the Si–O–Si bending, Si–OH or Si–O–Fe stretching, and Si–O–Si asymmetric stretching vibrations, respectively . The peak at 955 cm −1 can be used as an indirect indication of the coverage of the magnetic particles by functional groups.…”