Antibacterial Properties of Nano Zinc Oxide Powder Among the many nano-material antibacterial agents, nano-zinc oxide has a strong inhibitory or killing effect on pathogenic bacteria such as Escherichia coli, Staphylococcus aureus, and Salmonella, and nano-level zinc oxide is a new type of zinc source. With selective toxicity and good biocompatibility, it also has the characteristics of high biological activity, good immunomodulatory ability and high absorption rate, so it has been paid more and more attention by related researchers.
When the particle size is reduced to the nanometer level (20-30nm), the nanoparticle has a higher surface activity and a larger specific surface area, which increases the area of contact and reaction with the bacteria, so the toxicity of the nano-zinc oxide to the bacteria shows To find out a certain particle size dependence, the researchers studied the inhibitory effects of six different sizes of zinc oxide particles on the growth of Staphylococcus aureus, and found that when the particle size of nano-zinc oxide is >100nm (concentration is 6mmol.L-1) ), there is no obvious growth inhibitory effect on Staphylococcus aureus, and when its particle size is less than 30nm, it not only inhibits the growth of the bacteria, but even has a lethal effect on it.
Antibacterial mechanism of nano-zinc oxide
At present, there are many research reports on the antibacterial or sterilization of nano-zinc oxide. The existing literature mainly summarizes its antibacterial or sterilization mechanism into three aspects:
1. Release of free Zn2+;
The metabolic balance of the metal ion ZN2+ is essential for the survival of bacteria. Studies have shown that nano-zinc oxide slowly releases ZN2+ in an aqueous medium, and ZN2+ can penetrate the cell membrane to enter the cell, and while destroying the cell membrane, it reacts with certain groups on the protein to destroy the structure and physiological activity of the bacteria. It enters the enzyme that destroys the electron transfer system in the bacteria and reacts with -SH to achieve the purpose of sterilization, and after killing the bacteria, ZN2+ can be freed from the cell and repeat the above process.
2. The interaction between nanoparticles and the surface of bacteria;
The antibacterial properties of metal oxides can also be attributed to the interaction between nanoparticles and the surface of bacteria, which in turn causes damage to the surface of bacteria.
Researchers studied the effect of nanometer zinc oxide on the growth of Escherichia coli. The results show that when the pH value is 7, the potential of nano-zinc oxide is +24mV. When the surface of Escherichia coli produces a large amount of amide due to the hydrolysis of lipopolysaccharide, the bacterial membrane is negatively charged, and it is produced between the oppositely charged nano-zinc oxide Electrostatic attraction leads to a close association between the two and damages the surface of the bacteria, which in turn leads to the rupture of the bacterial membrane and ultimately the death of the bacteria. When the nano-zinc oxide particles interact with Campylobacter jejuni, the nano-particles can also cause changes in the morphology of the bacteria and leakage of the contents, and induce an increase in the expression of oxidative stress genes in the organism. The above studies have shown that the antibacterial properties of nano-zinc oxide are closely related to the interaction between the particles and the surface of the bacteria.
3. The generation of ROS reactive oxygen free radicals.
Metal oxide particles generate ROS (such as hydrogen peroxide, hydroxyl radicals, oxygen anions and hydroperoxides) in cells are also an important toxicity mechanism. The ROS induced by nanoparticles has been generally considered to be a common form of particle induction. The induced ROS can cause a series of biological reactions, such as damage to the bacterial membrane, which can cause lysis or promote the aggregation of nanoparticles in the bacterial body. Eventually cause the bacteria to die.
Nano-zinc oxide particles have photocatalytic properties, which can produce optical toxicity and cause lethal effects on bacteria under the irradiation of visible light or ultraviolet rays.
The researchers selected Escherichia coli and Bacillus subtilis as the test bacteria, and studied the damage degree of nano-zinc oxide to the two bacteria under light and dark conditions, respectively. It was found that the photocatalytic activity of the light-induced particles caused bacterial membrane breakage and DNA damage. At the same time, it was observed by SEM that the cells were sunken or only degraded bacterial membrane remained due to the leakage of bacterial contents.
Nano-zinc oxide is being widely used in the fields of animal husbandry, textiles, medical treatment, cosmetics and food packaging. The antibacterial effect of nano-zinc oxide is mainly concentrated on bacteria, such as Staphylococcus aureus and Escherichia coli, and shows good in vitro antibacterial applications. Get more information form https://www.hwnanomaterial.com/.