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Microbial infections due to biofilms on medical implants can be prevented by antimicrobial coatings on biomaterial surfaces. Mesoporous silica nanoparticles (MSNPs) were synthesized via base-catalyzed sol-gel process at room temperature, functionalized with phenazine-1-carboxamide (PCN) and characterized by UV-visible, FT-IR, DLS, XRD spectroscopic techniques, SEM, TEM, TGA and BET analysis. Native MSNPs, PCN and PCN-MSNPs were evaluated for anti- Candida minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), Candida albicans ( C . albicans ) biofilms and C . albicans-Staphylococcus aureus ( S . aureus ) polymicrobial biofilm inhibition. PCN-MSNPs were four-fold effective (MIC 3.9 µg mL −1 ; 17.47 µM) and MFC (7.8 µg mL −1 ; 34.94 µM) as compared to pure PCN (MIC 15.6 µg mL −1 ; 69.88 µM) and MFC (31.2 µg mL −1 ; 139.76 µM). PCN-MSNPs inhibited in vitro C . albicans MTCC 227 -S . aureus MTCC 96 biofilms at very low concentration (10 µg mL −1 ; 44.79 µM) as compared to pure PCN (40 µg mL −1 ; 179.18 µM). Mechanistic studies revealed that PCN induced intracellular ROS accumulation in C . albicans MTCC 227, S . aureus MTCC 96 and S . aureus MLS-16 MTCC 2940, reduction in total ergosterol content, membrane permeability, disruption of ionic homeostasis followed by Na + , K + and Ca 2+ leakage leading to cell death in C . albicans MTCC 227 as confirmed by confocal laser scanning micrographs. The silicone urethral catheters coated with PCN-MSNPs (500 µg mL −1 ; 2.23 mM) exhibited no formation of C . albicans MTCC 227 - S . aureus MTCC 96 and C . albicans MTCC 227 - S . aureus MLS -16 MTCC 2940 biofilms. This is the first report on PCN-MSNPs for use as antimicrobial coatings against microbial adhesion and biofilm formation on silicone urethral catheters.

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