Investigation of in vitro effects of cyanobacteria mediated silver nanoparticles on single and dual candida albicans and staphylococcus aureus biofilms

Biofilm structure protects microorganisms against adverse environmental conditions by making them resistant. Prokaryotic Staphylococcus aureus and eukaryotic Candida albicans microorganisms are opportunistic pathogens important for public health and are frequently isolated together from infections. Nanotechnological methods may offer promising results in resistant polymicrobial biofilm infections. This study investigated the biosynthesis and characterization of silver nanoparticles (AgNPs) from Cyanobacterial Chroococcus species, as well as the effects of AgNPs on single and dual S. aureus and C. albicans isolates in planktonic and biofilm form. According to the data obtained, the most suitable conditions for the synthesis of AgNPs were determined as extract ratio 3:1 v/v (cell extract/AgNO3), silver salt concentration 10 mM, pH 7, temperature 60 °C and time 30 minutes. The surface plasmon resonance (SPR) peak of AgNPs was observed at 420-430 nm, and AgNPs were observed by TEM with an average diameter of 11-13 nm and a spherical shape. EDX analysis revealed a strong elemental silver signal. The shift in the absorption bands after the formation of AgNPs was confirmed by FTIR analyses. X-ray diffraction analysis showed that AgNPs were in cubic crystal form. Zeta potential of AgNPs was found to be - 20 mV. MIC data showed that S. aureus was much more sensitive to AgNPs than C. albicans, with increased resistance to amphotericin and ampicillin in dual culture. TEM data supported that AgNPs acted with versatile targets in single and dual cultures, and SEM data supported that the application of AgNPs before biofilm formation was much more effective than after biofilm formation. XTT, hydrophobicity, SEM and CLSM findings parallelly revealed the biofilm inhibitory effects of AgNPs. However, the effect of AgNPs in the dual biofilm is less compared to the single biofilm. Ampicillin has a strong effect on dual biofilm. The effective, environmentally friendly and rapid synthesis of Chroococcus mediated AgNPs and their strong antibiofilm effects may create significant potential for their use in biomedical and environmental applications.