Antimicrobial Synergistic Effect Between Ag and Zn in Ag-ZnO·mSiO2 Silicate Composite with High Specific Surface Area

Abstract

Antimicrobial materials are widely used for inhibition of microorganisms in the environment. It has been established that bacterial growth can be restrained by silver nanoparticles. Combining these with other antimicrobial agents, such as ZnO, may increase the antimicrobial activity and the use of carrier substrate makes the material easier to handle. In the paper, we present an antimicrobial nanocomposite based on silver nanoparticles nucleated in general silicate nanostructure ZnO·mSiO2. First, we prepared the silicate fine net nanostructure ZnO·mSiO2 with zinc content up to 30 wt% by precipitation of sodium water glass in zinc acetate solution. Silver nanoparticles were then formed within the material by photoreduction of AgNO3 on photoactive ZnO. This resulted into an Ag-ZnO·mSiO2 composite with silica gel-like morphology and the specific surface area of 250 m2/g. The composite, alongside with pure AgNO3 and clear ZnO·mSiO2, were successfully tested for antimicrobial activity on both gram-positive and gram-negative bacterial strains and yeast Candida albicans. With respect to the silver content, the minimal inhibition concentration of Ag-ZnO·mSiO2 was worse than AgNO3 only for gram-negative strains. Moreover, we found a positive synergistic antimicrobial effect between Ag and Zn agents. These properties create an efficient and easily applicable antimicrobial material in the form of powder.

Antimicrobial Activity of Zinc Oxide Nano/Microparticles and Their Combinations against Pathogenic Microorganisms for Biomedical Applications: From Physicochemical Characteristics to Pharmacological Aspects

“…Combinatorial materials used with ZnO NPs/MPs also showed antimicrobial activity using different mechanisms to overcome multi-drug resistance. These included antibiotic or anti-inflammatory drugs [ 20 , 47 , 79 ], other metal oxide NPs/MPs or metal doping [ 80 , 81 ], polymers (e.g., chitosan and alginate) [ 28 , 82 , 83 ], carbon-based materials (e.g., graphene [ 84 , 85 ], graphene oxide (GO) [ 86 , 87 ], and reduced graphene oxide (rGO) [ 88 ]), and quantum dots (QDs) [ 89 , 90 ]. They enhanced ROS generation or mediated the other antimicrobial pathways of ZnO NPs/MPs in microorganisms to create an additive or synergistic microbial growth inhibition benefit.…”

“…They enhanced ROS generation or mediated the other antimicrobial pathways of ZnO NPs/MPs in microorganisms to create an additive or synergistic microbial growth inhibition benefit. However, the reduced or antagonistic disadvantages of antimicrobial performance sometimes occurred due to microbial susceptibility [ 20 , 81 , 91 ].…”

“…Titanium dioxide (TiO 2 ) NPs/MPs, 4A zeolite (Na 12 [(AlO 2 ) 12 (SiO 2 ) 12 ]·27H 2 O), and silica (SiO 2 ) were included in combinations of ZnO NPs/MPs [ 112 , 113 , 114 ]. In addition, doping of antibiotic metals (e.g., Ag and Cu) to ZnO NPs/MPs has been reported for enhanced antimicrobial performance [ 81 , 105 , 115 , 116 , 117 ].…”

“…The ZnO NPs/TiO 2 NPs/4A zeolites in combinations were cube-shaped at 400–600 nm, in which spherical ZnO NPs with ~50 nm were included. In addition, Ag-ZnO·mSiO 2 composites reported by Bednář et al [ 81 ], were lamellar porous nanostructures with Ag spots having 250 m 2 /g of specific surface area, and had antimicrobial activity against E. coli, P. aeruginosa, Streptococcus salivarius, S. aureus , and C. albicans at MIC levels of 2.9 mg/cm 3 , 3.9, 5.9, 5.9, and 23.5 mg/cm 3 , respectively. The Ag-ZnO·mSiO 2 composites also showed synergistic antimicrobial activity based on Ag and ZnO interaction, compared to ZnO·mSiO 2 alone.…”

Lamelary Aggregation of Nanoparticles from Frozen Liquid on the Sublimation Interface—Experimental Preparation and Application of Nanomaterials

“…As with other nanoparticulate materials, it is advantageous to deposit silver nanoparticles on a carrier micropowder material that facilitates handling and dosing. In our previous work [15], the carrier material was a network nanostructure of ZnO • mSiO 2 similar to silica gel, which is doped with zinc atoms in the form of semiconducting ZnO. After saturating the porous material ZnO • mSiO 2 with an aqueous solution of AgNO 3 , the nanoparticles of metallic silver Ag inside the porous silicate structure were prepared by photoreduction by the action of UV radiation at 200 nm for 100 min.…”