Cetylpyridinium chloride mouth rinses alleviate experimental gingivitis by inhibiting dental plaque maturation

Oral rinses containing chemotherapeutic agents, such as cetylpyridinium chloride （CPC）, can alleviate plaque-induced gingival infections, but how oral microbiota respond to these treatments in human population remains poorly understood. Via a double- blinded, randomised controlled trial of 91 subjects, the impact of CPC-containing oral rinses on supragingival plaque was investigated in experimental gingivitis, where the subjects, after a 21-day period of dental prophylaxis to achieve healthy gingivae, received either CPC rinses or water for 21 days. Within-subject temporal dynamics of plaque microbiota and symptoms of gingivitis were profiled via 16S ribosomal DNA gene pyrosequencing and assessment with the Mazza gingival index. Cetylpyridinium chloride conferred gingival benefits, as progression of gingival inflammation resulting from a lack of dental hygiene was significantly slower in the mouth rinse group than in the water group due to inhibition of 17 gingivitis-enriched bacterial genera. Tracking of plaque a and β diversity revealed that CPC treatment prevents acquisition of new taxa that would otherwise accumulate but maintains the original biodiversity of healthy plaques. Furthermore, CPC rinses reduced the size, local connectivity and microbiota-wide connectivity of the bacterial correlation network, particularly for nodes representing gingivitis- enriched taxa. The findings of this study provide mechanistic insights into the impact of oral rinses on the progression and maturation of dental plaque in the natural human population.

Temperature-modulated inversion and switching of chiroptical responses in dynamic side-by-side oligomers of gold nanorods

Herein,a new strategy is proposed for achieving dynamic chiral controls in self-assembly systems of plasmonic nanorods based on temperature-modulation.Via enlarging Au{100}side facets of Au nanorod(AuNR)building block and changing surface ligand from often-used cetyltrimethylammonium bromide(CTAB)to cetylpyridinium chloride(CPC),inversion of chiroptical signal in side-by-side(SS)oligomers is realized.Under the guide of chiral cysteine(Cys),Au{100}side facet-linked SS rods twist in the opposite direction compared with Au{110}side facet-linked counterparts.At high CPC concentration,by controlling the incubation temperature of chiral Cys,the dominant twist mode can be regulated.Finite-difference time-domain(FDTD)simulations indicate the key role of the twisting dihedral angle of the oligomers in driving chiral signal inversion.At low CPC concentration,a temperature-sensitive chiral switching is observed owing to the conformation change of the CPC ligand layer.The temperature-modulated chiral responses are based on the interactions of chiral molecules,achiral surface ligands,and exposed facets of the building block.The rich dynamic tunability of chiroptical responses of plasmonic assemblies may find applications in stimulus-responsive nanodevices.