Doxycycline‐functionalized polymeric nanoparticles inhibit Enterococcus faecalis biofilm formation on dentine

Abstract

Aim To evaluate in a laboratory setting the antimicrobial properties and the potential to inhibit biofilm formation of novel remineralizing polymeric nanoparticles (NPs) when applied to dentine surfaces and to ascertain the effect of the functionalization of these NPs with zinc, calcium or doxycycline. Methodology The antimicrobial activity and inhibition of biofilm formation of polymeric NPs were analysed on human dentine blocks that were infected with Enterococcus faecalis before or after application of NPs. LIVE/DEAD ® testing under Confocal Laser Scanning Microscopy and bacterial culturing were employed to analyse biofilm biovolume and bacterial viability. Field Emission Scanning Electron Microscopy was also employed to assess biofilm morphology. One‐way anova with Welch’s correction and post hoc comparison by the Games–Howell test were performed for comparisons between groups. Results The un‐functionalized NPs displayed the greatest antimicrobial activity against E. faecalis biofilms as they provided the lowest biovolume (3865.7 ± 2926.97 µm3; P < 0.001) and the highest dead/injured cells percentage (79.93 ± 18.40%; P < 0.001), followed by Dox‐NPs (biovolume: 19,041.55 ± 17,638.23 µm3, dead/injured cells: 45.53 ± 26.50%; P < 0.001). Doxycycline‐loaded NPs had the largest values of inhibition of biofilm formation with the lowest biofilm biovolume (8517.65 ± 7055.81 µm3; P < 0.001) and a high dead/injured bacterial percentage (68.68 ± 12.50%; P < 0.001). Un‐functionalized NPs did not reduce biomass growth (P > 0.05), but attained the largest percentage of compromised cells (93 ± 8.23%; P < 0.001), being able to disrupt biofilm formation. It also produced occlusion of dentinal tubules, potentially interfering with bacterial tubule penetration. Conclusions A new generation of bioactive nano‐fillers (doxycycline‐functionalized polymeric NPs) had antibacterial activity and occluded dentinal tubules. Incorporating these NPs into endodontic sealers may have the potential to enhance the outcome of root canal treatment.

Recent advances on nanomaterials for antibacterial treatment of oral diseases

“…Organic carriers are also very popular. The enhanced antibacterial effect of the carriers and the drug is also showed in the organic carriers [ 25 , [105] , [106] , [107] , [108] , [109] , [110] , [111] ]. Chen et al.…”

A critical analysis of research methods and experimental models to study irrigants and irrigation systems

“…Irregular surfaces can be easily imaged due to its larger depth of field compared to light microscopy (Azeredo et al, 2017; Morago et al, 2016; Figure 1). It has been widely used to confirm the presence or growth of a biofilm on a specimen and for qualitative evaluation of the effect of root canal irrigants on biofilm (Arias‐Moliz et al, 2021; Marinković et al, 2020; Shen et al, 2011). However, the specimens must undergo laborious preparation before imaging, including fixation, freeze‐ or critical‐point‐drying and coating with a conductive material.…”

The Potential Translational Applications of Nanoparticles in Endodontics

“… 165 Recently, the application of doxycycline-functionalized PolymP- n Active nanoparticles was found to occlude dentinal tubules and exert antibiofilm effects against E. faecalis . 166 …”

“… 177 As nanoparticles possess enhanced solubility, high surface-area-to-volume ratio and minute dimensions, nanoparticle-based carrier systems may improve the dissolution and absorption of bioactive molecules and drugs. 176 Several polymeric nanocarriers have been investigated in the context of conventional root canal treatment, such as those previously discussed including chitosan, PLGA and PolymP- n Active nanoparticles, 107 , 165 , 166 as well as regenerative therapies. 178–182 Bovine serum albumin-loaded chitosan nanoparticles were found to improve the viability of stem cells from the apical papilla (SCAP) and enhance alkaline phosphatase activity.…”