Antibacterial activity of zinc oxide nanoparticles (ZnO-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Many microorganisms exist in the range from hundreds of nanometers to tens of micrometers. ZnO-NPs exhibit attractive antibacterial properties due to increased specific surface area as the reduced particle size leading to enhanced particle surface reactivity. ZnO is a bio-safe material that possesses photo-oxidizing and photocatalysis impacts on chemical and biological species. This review covered ZnO-NPs antibacterial activity including testing methods, impact of UV illumination, ZnO particle properties (size, concentration, morphology, and defects), particle surface modification, and minimum inhibitory concentration. Particular emphasize was given to bactericidal and bacteriostatic mechanisms with focus on generation of reactive oxygen species (ROS) including hydrogen peroxide (H2O2), OH− (hydroxyl radicals), and O2 −2 (peroxide). ROS has been a major factor for several mechanisms including cell wall damage due to ZnO-localized interaction, enhanced membrane permeability, internalization of NPs due to loss of proton motive force and uptake of toxic dissolved zinc ions. These have led to mitochondria weakness, intracellular outflow, and release in gene expression of oxidative stress which caused eventual cell growth inhibition and cell death. In some cases, enhanced antibacterial activity can be attributed to surface defects on ZnO abrasive surface texture. One functional application of the ZnO antibacterial bioactivity was discussed in food packaging industry where ZnO-NPs are used as an antibacterial agent toward foodborne diseases. Proper incorporation of ZnO-NPs into packaging materials can cause interaction with foodborne pathogens, thereby releasing NPs onto food surface where they come in contact with bad bacteria and cause the bacterial death and/or inhibition.

/pdf/review-on-zinc-oxide-nanoparticles-antibacterial-activity-2smaigi8sc.pdf

Review on Zinc Oxide Nanoparticles: Antibacterial Activity and Toxicity Mechanism.

Antimicrobial nanomaterials for water disinfection and microbial control: Potential applications and implications

Surface modification of inorganic nanoparticles for development of organic–inorganic nanocomposites—A review

The antibacterial properties of zinc oxide nanoparticles were investigated using both Gram-positive and Gram-negative microorganisms. These studies demonstrate that ZnO nanoparticles have a wide range of antibacterial activities toward various microorganisms that are commonly found in environmental settings. The antibacterial activity of the ZnO nanoparticles was inversely proportional to the size of the nanoparticles in S. aureus. Surprisingly, the antibacterial activity did not require specific UV activation using artificial lamps, rather activation was achieved under ambient lighting conditions. Northern analyses of various reactive oxygen species (ROS) specific genes and confocal microscopy suggest that the antibacterial activity of ZnO nanoparticles might involve both the production of reactive oxygen species and the accumulation of nanoparticles in the cytoplasm or on the outer membranes. Overall, the experimental results suggest that ZnO nanoparticles could be developed as antibacterial agents agai...

Size-Dependent Bacterial Growth Inhibition and Mechanism of Antibacterial Activity of Zinc Oxide Nanoparticles

Nanofluids, the fluid suspensions of nanomaterials, have shown many interesting properties, and the distinctive features offer unprecedented potential for many applications. This paper summarizes the recent progress on the study of nanofluids, such as the preparation methods, the evaluation methods for the stability of nanofluids, and the ways to enhance the stability for nanofluids, the stability mechanisms of nanofluids, and presents the broad range of current and future applications in various fields including energy and mechanical and biomedical fields. At last, the paper identifies the opportunities for future research.

/pdf/a-review-on-nanofluids-preparation-stability-mechanisms-and-427pko83jc.pdf

A review on nanofluids: preparation, stability mechanisms, and applications

Nanoparticle metal oxides represent a new class of important materials that are increasingly being developed for use in research and health-related applications. Highly ionic metal oxides are interesting not only for their wide variety of physical and chemical properties but also for their antibacterial activity. Although the in vitro antibacterial activity and efficacy of regular zinc oxides have been investigated, little is known about the antibacterial activity of nanoparticles of ZnO. Preliminary growth analysis data suggest that nanoparticles of ZnO have significantly higher antibacterial effects on Staphylococcus aureus than do five other metal oxide nanoparticles. In addition, studies have clearly demonstrated that ZnO nanoparticles have a wide range of antibacterial effects on a number of other microorganisms. The antibacterial activity of ZnO may be dependent on the size and the presence of normal visible light. The data suggest that ZnO nanoparticles have a potential application as a bacteriostatic agent in visible light and may have future applications in the development of derivative agents to control the spread and infection of a variety of bacterial strains.

Antibacterial activity of ZnO nanoparticle suspensions on a broad spectrum of microorganisms

https://www.rsc.org/suppdata/cc/b7/b706633c/b706633c.pdf

Rapid and facile synthesis of siliceous MCM-48 mesoporous materials

The hydrolysis of Mg, Zr, and Ti alkoxides by water in solvent-alcohol mixtures has been examined in the absence of added acid or base catalysts, and herein, these data are reviewed. The presence of low dielectric constant solvents (benzene, toluene, or anisole), in varying ratios with methanol (or other alcohols), caused much more rapid gelation, subsequently yielding mesoporous materials with higher surface areas and larger pore volumes as fibrous, open web-like structures. The presence of high dielectric constant (polar aprotic) solvents such as acetone, acetonitrile, DMF, DMSO, or dimethyaniline was not effective in this way. A partial charge model was employed to explain why the low dielectric solvents forced more rapid hydrolysis, and it is concluded that the hydrolysis step is rate determining, approaching diffusion control, in this gelation process. The use of these “spectator solvents” helps simplify and enhance sol-gel and xerogel/aerogel synthesis schemes, and yields higher quality materials.

A review of the chemical manipulation of nanomaterials using solvents: Gelation dependent structures

The synthesis of lamellar mesostructured Mg(OH)2 was achieved through a surfactant templating route. Amphiphilic compounds with different anionic headgroups (phosphate, sulfate, sulfonate, and carboxylate) were used as surfactants. Control of d spacing was achieved through the use of different alkyl carboxylate amphiphiles. It is proposed that the interaction between the highly reactive oxygen atoms of the anionic surfactants and the highly electrophilic Mg atom leads to the formation of high charge density at the interface between the surfactant molecules and the inorganic precursor. This interaction is very strong and the existence of strong bonds between the headgroup molecules of the surfactant and the Mg atom locks the structure in a preferred orientation, i.e., lamellar mesostructure. The strong interaction thus precludes any phase transformation, and only the lamellar phase of Mg(OH)2 is obtained. Calcination of the surfactant by heating in oxygen flow leads to the collapse of the lamellar mesophas...

Koodali T. Ranjit

Papers

Antibacterial activity of ZnO nanoparticle suspensions on a broad spectrum of microorganisms

Rapid and facile synthesis of siliceous MCM-48 mesoporous materials

A review of the chemical manipulation of nanomaterials using solvents: Gelation dependent structures

Amphiphilic templating of magnesium hydroxide.

Nanoparticles in Environmental Remediation