Antimicrobial potential of consolidation polymers loaded with biological copper nanoparticles

Background: Biodeterioration of historic monuments and stone works by microorganisms takes place as a result of biofilm production and secretion of organic compounds that negatively affect on the stone matrix. Methods: Copper nanoparticles (CuNPs) were prepared biologically using the headspace gases generated by the bacterial culture Escherichia coli Z1. The antimicrobial activity of CuNPs was evaluated against the bacterial strains Bacillus subtilis, Micrococcus luteus, Streptomyces parvulus, Escherichia coli, Pseudomonas aeruginosa as well as some fungal strains Aspergillus niger, Aspergillus flavus, Penicillium chrysogenum, Fusarium solani and Alternaria solani. Results: Biological CuNPs demonstrated antibacterial and antifungal activities higher than those of the untreated copper sulfate. At the same time, limestone and sandstone blocks treated with consolidation polymers functionalized with CuNPs recorded apparent antimicrobial activity against E. coli, S. parvulus and B. subtilis in addition to an improvement in the physical and mechanical characters of the treated stones. Furthermore, the elemental composition of CuNPs was elucidated using electron dispersive x-ray system connected with the scanning electron microscope. Conclusion: Consolidation polymers impregnated with CuNPs could be used to restrain microbial deterioration in addition to the refinement of physico-mechanical behavior of the historic stones.