Developing a Silver Nanocomposite With Quorum-Quenching Enzyme Ag-Est816 to Prevent Periodontitis

Objective: The objective of this study was to synthesise a novel silver nanocomposite incorporating quorum-quenching enzyme N-acyl-homoserine lactone-lactonase Est816 (Ag-Est816) to inhibit periodontal biofilm formation. Methods: A one-pot reaction was employed to synthesise Ag-Est816 using silver nitrate, branched polyethyleneimine, and Est816. Ag-Est816 was characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Material stability was assessed by inductively coupled plasma spectrometry to determine the cumulative release rate of Ag⁺ and by a colorimetric enzyme activity assay to determine the retention rate of enzyme activity. Cytotoxicity toward human gingival fibroblasts (HGFs) was assessed using the Cell Counting Kit-8 (CCK-8) assay and immunofluorescent staining. Biomass of periodontal biofilm (Porphyromonas gingivalis and Streptococcus sanguinis) was analyzed using a crystal violet staining assay; viability and thickness were examined with confocal laser scanning microscopy. The biofilm and bacterial cells were examined using scanning electron microscopy (SEM) and TEM. Phosphate-buffered saline (PBS) served as the control. Results: DLS and TEM revealed spherical particles with a diameter of 98 ± 5 nm. XPS confirmed silver coordination bonds formation. The cumulative release rate of Ag⁺ was 0.19 ± 0.01%. The retention rate of enzyme activity was 93.3 ± 0.4% at 48 hours. Ag-Est816 was non-cytotoxic to HGFs, as evidenced by normal cytoskeletal morphology and no difference in cell proliferation compared to the PBS group (P = .36). The biomass in the Ag-Est816 and PBS groups was 0.82 ± 0.05 and 2.77 ± 0.16 (P< .001), and their live/dead ratios were 46 ± 6% and 80 ± 5%, respectively (P< .001). SEM revealed dispersed biofilms, and TEM showed bacterial cells with disrupted membranes in the Ag-Est816 group. Conclusion: This study developed a novel Ag-Est816 antibacterial nanocomposite effective against periodontal biofilm. Clinical significance: Ag-Est816 warrants future investigation for the localized control of periodontal biofilms.