Ultrasound-assisted synthesis of bismuth-metal organic frameworks for suppressing Porphyromonas gingivalis

Abstract

Objectives: Our group recently reports the dramatic inhibitory effect of bismuth drugs on the ‘keystone’ periodontopathogen - Porphyromonas gingivalis in its planktonic, biofilm and intracellular states. Meanwhile, metal-organic-frameworks (MOFs) show great potentials in the biomedical field as multifunctional drug vehicles. Herein, we aimed to construct colloidal bismuth MOFs (Bi-MOFs) via an ultrasound-assisted facile approach and investigate their antibacterial effects on P. gingivalis. Methods: Distinct morphologies of Bi-MOFs from varied concentrations were synthesized with single/co-solvent systems via a single-step ultrasonic method. The scanning electron microscope (SEM) and X-ray diffractometer (XRD) were conducted to examine the morphologies and crystallinity of the Bi-MOFs. Meanwhile, the X-ray photoelectron spectroscopy (XPS) was used to analyze the functional groups of the particles, and the broth microdilution assay was performed to determine the minimum inhibitory concentrations (MIC) of the Bi-MOFs against the planktonic P. gingivalis (ATCC 33277) at 48 and 72 h. Results: In general, the average particle size of the Bi-MOFs had a positive correlation with the amount of metal presented in the solvent system. By adjusting the MeOH percentage in DMF, Bi-MOFs could show unique hexagonal and thread-like morphologies under SEM. These observations suggested that the colloidal Bi-MOFs might have undergone a different formation pathway. In addition, all the Bi-MOFs exhibited promising antibacterial effects towards P. gingivalis, while the MOFs obtained from MeOH-only solvent system produced the most potent antimicrobial effect among all the samples. Conclusions: The ultrasound-assisted Bi-MOFs with potent antibacterial effects could effectively suppress P. gingivalis. This work may lay down the foundation to develop novel vehicles with encapsulation of anti-inflammatory agents/antimicrobials for modulating immuno-inflammatory responses in the treatment of periodontal diseases.