Improved gypsum plaster by incorporation of zinc oxide nanoparticles (ZnO-NPs)

摘要

Gypsum plaster is used in linings, coatings, decorative elements, and sealing and is a component of drywall. However, it is susceptible to the development of mold and other microorganisms, especially in hot and humid environments with poor ventilation and sunshine. In order to provide antimicrobial activity to the gypsum, zinc oxide nanoparticles (ZnO-NPs) were added to its matrix. Two types of ZnO-NPs were synthesized, by simple precipitation of sulfate heptahydrate (ZnSO4 center dot 7H(2)O) by sodium hydroxide (NaOH) and with the use of lauryl sulfate, resulting in nanoparticles with a diameter similar to 40 nm. The antimicrobial activity was assessed by the microdilution technique for determination of minimum inhibitory concentration against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Aspergillus niger. SEM images and the count of CFU present in the Staphylococcus aureus biofilm in the specimens composed of reference gypsum and with 15% ZnO-NPs of both syntheses show the efficacy of ZnO-NPs in the gypsum matrix against biofilm (p < 0.05). The specimens with ZnO-NPs also did not allow the proliferation of Aspergillus niger. Therefore, this new material, by preventing the proliferation of these microorganisms, will benefit the health of its users as well as the environment, due to the reduction in the use of chemicals to clean it. Consequently, bringing economic and environmental benefits.