Eco-friendly green synthesis of ZnO/GQD nanocomposites using Protoparmeliopsis muralis extract for their antibacterial and antibiofilm activity

Over the last few years, the emergence and widespread distribution of microbial resistance to antibiotics is world-wide challenge in the medical science. In this regard, lichens are one promising antimicrobial agent which could be replaced by traditional antibiotics due broad-spectrum with potent antimicrobial activity. In this study, the ZnO/GQDs nanocomposites (NCs) and Protoparmeliopsis muralis extract-grafted ZnO/GQDs NCs have been prepared via green method. The prepared products are characterized with XRD analysis, SEM and FTIR. Interestingly, the linking of Protoparmeliopsis muralis extract into ZnO/GQDs NCs demonstrated strong antibacterial activity with to 5-log reduction in bacterial CFU/ml compared to P. muralis for at 4 days. Additionally, the nanocarrier demonstrated to 88 and 83% inhibition of biofilm formation when tested against methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant Enterococcus faecalis (VRE) respectively. Finally, results this study reported that the use of the P. muralis/ZnO/GQDs-NCs formulation could be employed as a novel agent antibacterial to inhibit bacterial growth and the biofilm formation. (C) 2021 Elsevier B.V. All rights reserved.