A liquid crystalline precursor incorporating chlorhexidine acetate and silver nanoparticles for root canal disinfection

Abstract

Lyotropic liquid crystals (LLC) have received increasing attention as a drug delivery system. In this study, a novel intra-canal disinfectant based on the glycerol monooleate (GMO) LLC precursor incorporation with chlorhexidine (CHX) and silver nanoparticles (Ag-NPs) was designed and evaluated. The LLC precursor with excellent fluidity was able to penetrate deeply into the complex tiny collateral branch root canals. The transformation of cubic LLC in root canals upon coming into contact with water provided long-lasting disinfection against multidrug-resistant bacteria to avoid the endodontic reinfection and follow-up visits. The GMO-ethanol-water (48% : 12% : 40%, w/w) formulation containing 0.5% CHX and 0.02% Ag-NPs was selected for further studies. The low viscosity of the precursor presented excellent injectability and flowabilities. From the in vitro release test, the release behaviours were found to be influenced by CHX and Ag-NP contents, allowing the optimized precursor to obtain a 28-day release profile. The CHX-Ag-NP containing LLC precursor exhibited an excellent and sustained sterilization effect on Enterococcus faecalis for more than one month with a bacterial inactivation rate of ≥98.5%, which was far more than the minimum clinical requirement (7 days). Furthermore, no in vitro toxicity was observed in the cytotoxicity evaluation. The CHX-Ag-NP containing LLC precursor was proved to be a promising intra-canal disinfectant in our study.

Application of Antimicrobial Nanoparticles in Dentistry

“…Chlorhexidine (CHX)-AgNPs containing lyotropic liquid crystals (LLC) exhibited excellent and sustained sterilization and inhibitory effect on E. faecalis lasting for more than one month with a bacterial inactivation rate of ≥98.5%. Besides, no toxicity was observed in the cytotoxicity evaluation [60]. However, the latest literature showed that AgNPs irrigant was less effective against E. faecalis biofilm and infected dentinal tubules than NaOCl [61], which was consistent with the result that AgNPs gel was more effective as irrigant agent than solution form [62].…”

“…However, there are other sounds according to the toxicity of NPs [19,60,95,141]. A previous study found that the toxicity of NPs had a strong correlation with the time, rather than with the concentration of antimicrobial NPs [19].…”

Smart phase transformation system based on lyotropic liquid crystalline@hard capsules for sustained release of hydrophilic and hydrophobic drugs

“…In our previous study, a LLC system loaded with silver nanoparticles and chlorhexidine acetate was established by us. No synergistic release behaviors were observed due to the same hydrophilic property and the huge different in size of two drugs (Zheng et al, 2018). Further study on the LLC system loaded with both the hydrophilic and hydrophobic drugs is meaningful and to be conducted in the near further.…”

“…The special structures provide incorporation of drugs with different solubility, including hydrophilic, hydrophobic and amphiphilic molecules (Conn & Drummond, 2013;Rajabalaya et al, 2017) and also tunable release rate (Rizwan & Boyd, 2015;Abd-Allah et al, 2016;Huang & Gui, 2018). LLC exhibits perfect performance on mucosal (Huang et al, 2017), transdermal (Peng et al, 2015;Musa et al, 2017), periodontal (Mei et al, 2017a;Zheng et al, 2018), subcutaneous (Mei et al, 2017b) and other parenteral drug delivery (Wan et al, 2015;Qin et al, 2016), due to its high drug-loading capacity, appropriate viscoelasticity and good biocompatibility (Abd-Allah et al, 2016;Kulkarni & Thareja, 2016).…”

Novel self-assembling conjugates as vectors for agrochemical delivery

“…LC systems have been shown to have high pharmaceutical value for their ability to deliver a range of molecules such as curcumin [ 13 ], chlorhexidine [ 14 ] and insulin [ 15 ]. LC systems encompass a number of phases such as lamellar phases, hexagonal phases and inverse bicontinuous cubic phases.…”