Evaluation of bacterial anti‐adhesion and sustained antimicrobial abilities of chlorhexidine gluconate‐loaded phase‐transited lysozyme nanoparticle suspension on dentine: An ex vivo study

Abstract Aim To evaluate the effect of chlorhexidine gluconate‐loaded phase‐transited lysozyme (CHG@PTL) coating on inhibiting bacterial adhesion and biofilm formation in an ex vivo root canal dentine model. Methodology The physicochemical and structural characteristics of CHG@PTL nanoparticle suspension and its coating formed on the dentine surface were analysed by thioflavin T fluorescence assay, transmission electron microscopy and confocal laser scanning microscopy (CLSM). The sustained chlorhexidine release profile of the CHG@PTL coating on the dentine surface was compared with that of the 2% CHG solution. By comparing with phosphate‐buffered saline, 1% sodium hypochlorite and 2% CHG solutions, the sustained antibacterial ability of the CHG@PTL coating and its effects on adhesion and biofilm formation of three types of bacteria ( E. faecalis , S. mutans , and A. viscous ) were analysed in ex vivo root canal dentine models using the serial plate transfer test (SPTT) and CLSM with live/dead bacterial staining , respectively. Results CHG promoted the lysozyme protein to form a higher proportion of β‐sheet structure during phase transition. In the CHG@PTL nanoparticle suspension, characteristic drug‐loaded nanospheres with a high concentration of CHG molecules inside and an outer PTL nanofilm were observed, and they formed a thinner and tighter coating on the dentine surface. The CHG@PTL coating on the dentine surface showed a significantly higher cumulative release amount of chlorhexidine than that of 2% CHG ( p < .05). The results of SPTT showed that the CHG@PTL coating had a longer antibacterial duration than the control groups. After 12 h of incubation, a higher number of bacteria were agglutinated on the CHG@PTL coating surface compared to the control groups ( p < .05). After 7 days of incubation, the number of agglutinated bacteria significantly decreased. At two time points, the percentage of dead bacteria on the CHG@PTL coating surface was the highest among all experimental groups based on CLSM observation (over 99.9% for all three bacteria, p < .001). Conclusions CHG@PTL nanoparticle suspension could form an antimicrobial coating on the surface of dentine with a novel ‘agglutinating bacteria and sterilizing’ mode.