Microbicidal Activity of Artificially Generated Hydroxyl Radicals

Abstract

The hydroxyl radical, one of the reactive oxygen species, has one unpaired electron in the structure, so that it tends to deprive other substances of an electron which is so-called oxidation. It is known that hydroxyl radicals produced by immunological response kill invading microorganisms by the oxidation. Besides the immune system, it has been demonstrated that hydroxyl radicals play an important role in the bactericidal action of antibiotics. In this context, we have conducted a research to develop disinfection techniques utilizing artificially generated hydroxyl radicals. We adopted photolysis of H 2 O 2 , sonolysis of water and the other photo-chemical reaction as generators of hydroxyl radicals. A series of studies demonstrated that the microbicidal activity of hydroxyl radicals was sufficient to kill bacteria in an experimental biofilm as well as planktonic bacteria and fungi within a short-treatment time. In addition, the safety aspect is confirmed by an in vivo study and a literature review. Thus, it is suggested that disinfection treatment utilizing artificially generated hydroxyl radicals can be applicable to medical/dental therapy as novel disinfection treatments.

Cold Plasma: Clean Technology to Destroy Pathogenic Micro-organisms

“…Here, Ar gas was bubbled through the 11% H 2 O 2 solution to carry H 2 O 2 vapour in plasma resulting in the occurrence of characteristic OH peek at 281 and 309 nm (Pearse and Gaydon 1950). This OH radical plays an important role in sterilization process (Sheng et al 2014). Apart from that, Characteristic H α line at 656 nm and Ar I and OI lines can also be seen in the spectra.…”

“…H 2 O 2 decomposes in plasma environment and produces biocidal hydroxyl and hydroproyl free radicals and also H 2 O 2 molecules in excited state. The latter is a source of UV radiation which also helps in sterilization process (Sheng et al 2014).…”

Cold Plasma: Clean Technology to Destroy Pathogenic Micro-organisms

“…H 2 O 2 decomposes in plasma environment and produces biocidal hydroxyl and hydroproyl free radicals and also H 2 O 2 molecules in excited state. The latter is a source of UV radiation which also helps in sterilization process [8].…”

“…Here, Ar gas was bubbled through the 11% H 2 O 2 solution to carry H 2 O 2 vapour in plasma resulting in the occurrence of characteristic OH peek at 281 & 309 nm[10]. This OH radical plays an important role in sterilization process[8]. Apart from that, Characteristic H α line at 656 nm and Ar I and OI lines can also be seen in the spectra.…”

The Whitening Effect and Histological Safety of Nonthermal Atmospheric Plasma Inducing Tooth Bleaching

“…This theory supports that the production of ·OH radical is hastened by temperature increase [ 22 ]. OH radical induces oxidative damage on cells and tissues, so that chronical generation of it could lead to specific diseases [ 23 ]. Numerous studies have proved that light-activated bleaching did not produce any perceivable color changes [ 24 ].…”