Inhibition of Polymicrobial Biofilms of Candida albicans–Staphylococcus aureus/Streptococcus mutans by Fucoidan–Gold Nanoparticles

Abstract

The polymicrobial proliferation and development of complex biofilm morphologies by bacterial and fungal pathogens in the host are some of the key factors contributing to the failure of antimicrobial treatments. The polymicrobial interaction of Candida albicans and some bacterial species has been extensively studied in both in vitro and in vivo model systems. Alternative strategies for disrupting polymicrobial interaction and biofilm formation are constantly needed. Among several alternative strategies, the use of nanoparticles synthesized using a natural product in the treatment of microbial infection has been considered a promising approach. The current study aimed to synthesize gold nanoparticles (AuNPs) using a natural product, fucoidan, and to test their efficacy against mono and duo combinations of fungal (Candida albicans) and bacterial (Staphylococcus aureus/Streptococcus mutans) biofilms. Several methods were used to characterize and study Fu–AuNPs, including UV-vis absorption spectroscopy, FTIR, FE-TEM, EDS, DLS, zeta potential, and XRD. The concentration-dependent inhibition of early-stage biofilms and the eradication of mature biofilms of single species of C. albicans, S. aureus, and S. mutans have been observed. Early biofilms of a dual-species combination of C. albicans and S. aureus/S. mutans were also suppressed at an increasing concentration of Fu–AuNPs. Furthermore, Fu–AuNPs significantly eradicated the established mature biofilm of mixed species. The treatment method proposed in this study, which involves the use of marine-bioinspired nanoparticles, is a promising and biocompatible agent for preventing the growth of polymicrobial biofilms of bacterial and fungal pathogens.

Inhibition of Mixed Biofilms of Candida albicans and Staphylococcus aureus by β-Caryophyllene-Gold Nanoparticles

“…The S. aureus and C. albicans biofilms that developed individually or in mixed forms were inhibited in a concentration-dependent manner. Previous studies have shown similar inhibitory effects of AuNPs synthesized using natural compounds against polymicrobial biofilms of S. aureus and C. albicans in a concentration-dependent manner [ 50 ]. However, drug resistance has become a major challenge in eradicating established mature biofilms [ 53 ].…”

“…The β-c-AuNPs synthesized in this study were found to have antimicrobial activity against S. aureus and C. albicans . Our investigation showed an identical MIC value of β-c-AuNPs against S. aureus and C. albicans , despite the fact that the MIC values of different AuNPs synthesized using naturally derived chemicals show varying activities against various microbial pathogens [ 50 ]. Here, nanoparticles were synthesized using a natural pure compound called β-caryophyllene, which enables the pinpointing of key molecules involved in antimicrobial activity [ 15 ].…”

“…The eradication effects of β-c-AuNPs on the single-species biofilms of S. aureus and C. albicans were also higher at and above MIC. The recalcitrant nature of biofilm polymeric substances results in high drug concentrations required for the inhibition of mature biofilms [ 50 , 54 ]. Previous studies have shown that AuNPs synthesized using natural compounds at and above MIC can destroy mature single- or mixed-species biofilms [ 50 , 55 ].…”

“…The recalcitrant nature of biofilm polymeric substances results in high drug concentrations required for the inhibition of mature biofilms [ 50 , 54 ]. Previous studies have shown that AuNPs synthesized using natural compounds at and above MIC can destroy mature single- or mixed-species biofilms [ 50 , 55 ]. However, because of the enhanced biofilm formation in a synergistic manner in mixed-species biofilms, inhibiting them at the initial stage or eradicating mature biofilms requires a high concentration of drugs [ 50 ].…”

“…The synthesis of β-c-AuNPs was carried out exactly as described previously [ 50 ]. In brief, the reaction was carried out in a volume of 200 mL of deionized water by first dissolving 1 mM of HAuCl 4 .3H 2 O (pH 9.0) and stirring at 60 °C.…”