An improved understanding of the dispersion of multi-walled carbon nanotubes in non-aqueous solvents

Regenerable antimicrobial N-halamine/silica hybrid nanoparticles (NPs) containing chlorinated 5,5-dimethylhydantoinyl (Cl-DMH) groups, Cl-DMH/SiO₂ hybrid NPs, have been prepared by a co-condensation reaction between N-(3-triethoxysilylpropyl)-5,5-dimethylhydantoin (TS-DMH) and tetraethoxysilane (TEOS) and then a chlorination reaction in NaClO solution. The as-synthesized Cl-DMH/SiO₂ NPs were characterized by transmission electron microscopy, Scanning electron microscopy, X-ray photoelectron spectra, Specific surface area, Differential scanning calorimetry, and Fourier transform infrared. Experimental results showed that the size of the as-synthesized Cl-DMH/SiO₂ NPs could be well adjusted by changing the mass ratio of TS-DMH/TEOS and the volume ratio of 28 % NH₄OH/H₂O. Antimicrobial tests showed that the as-prepared Cl-DMH/SiO₂ hybrid NPs had excellent antimicrobial activities against both Escherichia coli and Staphylococcus aureus. The minimum inhibitory concentration and minimum bactericidal concentration values of the as-prepared Cl-DMH/SiO₂ hybrid NPs are 15 and 20 μg/mL for S. aureus, 25 and 30 μg/mL for E. coli, respectively. Paper disk diffusion assay showed that smaller-sized Cl-DMH/SiO₂ hybrid NPs have bigger inhibition zone diameters, indicating stronger antimicrobial efficacies. Also, the storage stability and regenerability of Cl-DMH/SiO₂ hybrid NPs were investigated.