Antibacterial and Antibiofilm Activity of Nanocomposites in Multi-Drug Resistant Streptococcus mutans

Abstract

Background. The nano-method has been used to create new, non-traditional antimicrobial agents. It is a successful treatment for infectious diseases and offers several benefits over conventional antibiotics, such as no side effects, enhanced effectiveness against drug-resistant organisms, and the ability to prevent the emergence of resistance that disrupts several biological processes. Aim. This study aimed to synthesize and characterize nanoparticles and investigate their antibacterial and anti-biofilm effects against Streptococcus mutans. Methods. Chitosan nanoparticles (Ch-NPs) were acquired from the Ministry of Science and Technology. FTIR analysis was used to validate the diagnosis, and a methanolic extract of Annona muricata was used to prepare green silver nanoparticles (Ag-NPs), which were characterized using UV-VIS spectroscopy, where the absorption of the formed AgNPs was at 427 nm at room temperature. The magnetic graphene nanocomposite (rGO/Fe3O4-NPs) was prepared physically. The nanocomposite rGO/Fe3O4.Ch-Ag-NPs was then created by combining nanoparticles of Ch-NPs, Ag-NPs, and rGO/Fe3O4-NPs (mix), and identified using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Numerous tests were carried out on the nanoparticles, including assessment of antibacterial efficacy, determination of the minimum inhibitory concentration (MIC), and evaluation of biofilm development. According to the diagnostic findings, the single or mixed nanoparticles had a spherical form. Two Streptococcus mutans isolates were examined for antibiotic sensitivity, and the findings indicated that the isolates were resistant to the majority of drugs. Results. The results of the disc diffusion method evaluation of the antibacterial activity of nanoparticles revealed that, at concentrations of 128 μg/ml, the nanocomposite rGO/Fe3O4.Ch-Ag-NPs (Mix) was more effective than Ch-NPs, Ag-NPs, and rGO/Fe3O4-NPs. The Streptococcus mutans isolates had the highest inhibition zones, measuring 17.67 ± 0.58 and 17.33 ± 0.58 mm in isolates No. (2) and (1), respectively, when compared with Ch-NPs, Ag-NPs, and rGO/Fe3O4-NPs. Ag-NPs and Ch-NPs had a minimum inhibitory concentration (MIC) of 32 μg/ml on two Streptococcus mutans isolates. However, for two isolates of Streptococcus mutans, the MIC of the rGO/Fe3O4-NPs (Mix) was 16 μg/ml. On two isolates of Streptococcus mutans, however, the MIC of the rGO/Fe3O4.Ch-Ag-NPs (Mix) was 8 μg/ml. Ag-NPs and rGO/Fe3O4-NPs completely prevented Streptococcus mutans from forming biofilms at 16 μg/ml, whereas Ch-NPs completely prevented Streptococcus mutans isolates from forming biofilms at 32 μg/ml. However, at 4 μg/ml, the nanocomposite rGO/Fe3O4.Ch-Ag-NPs (Mix) completely inhibited the anti-biofilm activity of Streptococcus mutans isolates. Conclusion. The synthesized nanocomposite rGO/Fe3O4.Ch-Ag-NPs exhibited superior antibacterial and antibiofilm activities against multidrug-resistant Streptococcus mutans compared with the individual nanoparticles. The nanocomposite showed the lowest MIC and effectively inhibited biofilm formation, indicating its potential as a promising antimicrobial agent against resistant Streptococcus mutans isolates.