Pushpa Thirubuvanesvari-Duraivelu, Siti Salwa Abd Gani, Masriana Hassan, Mohd Izuan Effendi Bin Halmi, Reem Fawaz Abutayeh, Mohammad A. A. Al-Najjar and Ala’ Abu-Odeh

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GREEN-SYNTHESIZED SILVER/SILVER CHLORIDE NANOHYBRIDS FROM PHOENIX DACTYLIFERA L. AJWA SEED EXTRACT EXHIBIT POTENT ANTIBACTERIAL AND ANTIBIOFILM ACTIVITIES AGAINST STAPHYLOCOCCUS EPIDERMIDIS AND ENTEROCOCCUS FAECALIS   

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Abstract 

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The increasing prevalence of multidrug-resistant (MDR) biofilm-forming pathogens has intensified the search for sustainable antimicrobial nanomaterials capable of overcoming conventional antibiotic resistance. Green-synthesized silver nanohybrids offer a sustainable strategy, yet their efficacy against clinically important Gram-positive nosocomial bacteria, Staphylococcus epidermidis and Enterococcus faecalis, remains poorly understood. These pathogens contribute to postoperative infections, biofilm-associated complications, increased healthcare costs, and mortality, with E. faecalis recognized as a WHO-priority pathogen owing to its intrinsic antimicrobial resistance and biofilm-associated persistence. This study evaluates the antibacterial and antibiofilm efficacy of biosynthesized silver/silver chloride nanoparticles (Ag/AgCl-NPs) from Ajwa seed extract (AjS) against these pathogens. Antibacterial activity was determined using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), tolerance level (TL), and crystal-violet based biofilm inhibition assay. AjS-Ag/AgCl-NPs exhibited MIC values of 0.020 and 0.156 mg/mL, and MBC values at 0.078 and 0.312 against S. epidermidis and E. faecalis, respectively. These values outperformed crude AjS and commercial AgNPs (c-AgNPs) against both bacterial strains. The nanohybrid demonstrated a bactericidal effect, with TL values of 4 and 2 against S. epidermidis and E. faecalis, respectively. Biofilm inhibition was prominent against S. epidermidis, achieving 88.62% inhibition at 2*MIC (0.040 mg/mL), whereas E. faecalis required 0.312 mg/mL to reach 87.69% inhibition. These findings support the development of Ajwa-derived Ag/AgCl nanohybrids as sustainable nanotherapeutic candidates for preventing biofilm-associated hospital infections, especially against S. epidermidis biofilms at lower concentrations. To our knowledge, this is the first study evaluating Ajwa seed-derived Ag/AgCl nanohybrids against both strains using integrated MIC, MBC, tolerance-level, and antibiofilm analyses.

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