Cooperative Antibacterial Effect Using Lactonase Est816-Ag Polymer Nanocomposite

Objectives: To synthesize an advanced polymer nanocomposite, quorum quenching lactonase Est816-Ag nanocomposite, and investigate its physicochemical property and antibacterial against Porphyromonas gingivalis (P. gingivalis) co-cultured with Streptococcus sanguis (S. sanguis).
Methods: Est816-Ag nanocomposite was synthesized using a one-pot reaction and then its physicochemical property was characterized using dynamic light scattering, circular dichroism, fluorescence spectroscopy, and X-ray photoelectron spectroscopy. The morphology, viability, and ultrastructure of P. gingivalis co-cultured with S. sanguis treated by Est816-Ag nanocomposite were assessed using scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM). No treatment was included as a negative control and group treated with Est816 or nanosliver was included as positive control for comparison
Results: Chemical characterization analysis indicated an Ag-N coordination between silver and the polymer/protein in the Est816-Ag nanocomposite with an average particle diameter of 102 nm and an enzymatic activity of 6 U/ml. SEM demonstrated scattered biofilm growth in Est816-Ag group, in contrast to confluent growth in the control. The live cell ratio under CLSM for Est816-Ag treatment and control were 15±5 and 85±8, respectively (p<0.01). TEM revealed damaged cell and cytoplasmic membranes after Est816-Ag nanocomposite treatment, in contrast to the intact cell morphology observed in the control.
Conclusions: The novel approach of integrating quorum quenching lactonase Est816 with silver nanoparticles provides stable physicochemical properties and enhanced antibiofilm efficacy against oral biofilm.