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This work aims to study the production of hydrogen peroxide gas (H2O2) through photocatalysis. It consists of two main parts. In the first part, we explore the optimal conditions for synthesizing H2O2 gas from humidity using a gas system photoreactor. Through experimentation, we discovered that the fabricated photoreactor, equipped with three series of coated photocatalyst-supporting plates, can synthesize H2O2 gas up to 3 ppmv. The photoreactor incorporates key components, including a photocatalyst material, UV light source, ventilation fan, and air filter. The identified optimal conditions included a relative humidity of 60‒65% RH and an air flow rate of 12.0 m/s. The TiO2/1%SiO2 photocatalyst, composed of SiO2 particles smaller than 63 μm, yielded the most favorable results. The second part focused on studying the role of SiO2 in TiO2/SiO2. We observed that modifying the TiO2 morphology with SiO2 created a pore structure on the surface. This structural modification leads to the formation of Ti‒O‒Si bonds, which facilitate electron and hole trapping on the photocatalyst surface. Furthermore, the presence of hydroxyl groups on the surface enhanced the attraction of reactant molecules. XRD results reveal a mixed-phase structure of TiO2 (anatase‒rutile)/SiO2 amorphous, contributing to improved electron and hole pathways within the photocatalyst. [ABSTRACT FROM AUTHOR]

In this paper, the problems of elimination of surface contamination with biological substances were characterised. The possibility of SARS-CoV-2 virus contamination of various surfaces was analysed. Disinfection processes were characterised, including the method using hydrogen peroxide gas. The test results of disinfection effectiveness and material compatibility of selected products, mainly these made of paper, disinfected by means of hydrogen peroxide gas were presented.

Prions are infectious agents causing prion diseases, which include Creutzfeldt–Jakob disease (CJD) in humans. Several cases have been reported to be transmitted through medical instruments that were used for preclinical CJD patients, raising public health concerns on iatrogenic transmissions of the disease. Since preclinical CJD patients are currently difficult to identify, medical instruments need to be adequately sterilized so as not to transmit the disease. In this study, we investigated the sterilizing activity of two oxidizing agents, ozone gas and vaporized hydrogen peroxide, against prions fixed on stainless steel wires using a mouse bioassay. Mice intracerebrally implanted with prion-contaminated stainless steel wires treated with ozone gas or vaporized hydrogen peroxide developed prion disease later than those implanted with control prion-contaminated stainless steel wires, indicating that ozone gas and vaporized hydrogen peroxide could reduce prion infectivity on wires. Incubation times were further elongated in mice implanted with prion-contaminated stainless steel wires treated with ozone gas-mixed vaporized hydrogen peroxide, indicating that ozone gas mixed with vaporized hydrogen peroxide reduces prions on these wires more potently than ozone gas or vaporized hydrogen peroxide. These results suggest that ozone gas mixed with vaporized hydrogen peroxide might be more useful for prion sterilization than ozone gas or vaporized hydrogen peroxide alone.

Abstract: Biodegradable poly(d,l-lactic-co-glycolic acid) (PLGA) has been widely used as a scaffold in tissue engineering due to its excellent biocompatibility. However, PLGA scaffolds become structurally deformed during the sterilization process since they were hydrolytically unstable. In this study, the effects of hydrogen peroxide gas (HPG) were investigated on the deformation, sterilization and cytocompatibility of porous PLGA scaffolds and compared with those of ethylene oxide (EO) gas. Also, the effects of HPG treatment on the cellular responses of human articular chondrocytes were examined. HPG treatment resulted in neither deformation of PLGA nor its chemical modification, different from EO gas treatment. PLGA scaffolds inoculated with diverse strains of microorganisms were completely sterilized by HPG treatment. Moreover, the cytotoxicity of residual HPG occurring upon HPG treatment completely decreased as ventilation time increased. On the other hand, there was no significant difference in the proliferation and glycosaminoglycan synthesis of chondrocytes between EO gas-treated and HPG-treated PLGA scaffolds. These results suggest that HPG can be used as an alternative method for sterilizing various polymeric scaffolds and medical devices without structural deformation. [Copyright &y& Elsevier]

To date, there have been no studies on the sterilization of prions by non-concentrated and concentrated vaporized hydrogen peroxide (VHP) applied by the same instrument. Here, the effect of the two types of VHP applied using an ES-700 sterilizer on prions was investigated. Brain homogenate from scrapie (Chandler) prion-infected mice was spotted on a cover glass and subjected to ES-700 treatment in soft (non-concentrated VHP from 59% hydrogen peroxide) or standard (concentrated VHP from 80% hydrogen peroxide) mode. Proteinase K-resistant prion protein (PrPres), an indicator of the abnormal isoform of prion protein (PrPSc), was reduced by ES-700 treatment under several conditions: SFT1/4 (soft mode, quarter cycle), SFT1/2 (soft mode, half cycle), SFT1 (soft mode, full cycle), and STD1/2 (standard mode, half cycle). PrPres was detected after the first and second rounds of protein misfolding cyclic amplification (PMCA) of untreated samples, but was undetectable in SFT1/4, SFT1/2, SFT1, and STD1/2 treated samples. In a mouse bioassay, SFT1/2 and STD1/2 treatment of prions significantly prolonged survival time, suggesting that prion infectivity is reduced after ES-700 treatment. In summary, both non-concentrated and concentrated VHP inactivate prions and may be useful for the low-temperature sterilization of prion-contaminated medical devices. [ABSTRACT FROM AUTHOR]

Prions are infectious agents causing prion diseases, which include Creutzfeldt-Jakob disease (CJD) in humans. Several cases have been reported to be transmitted through medical instruments that were used for preclinical CJD patients, raising public health concerns on iatrogenic transmissions of the disease. Since preclinical CJD patients are currently difficult to identify, medical instruments need to be adequately sterilized so as not to transmit the disease. In this study, we investigated the sterilizing activity of two oxidizing agents, ozone gas and vaporized hydrogen peroxide, against prions fixed on stainless steel wires using a mouse bioassay. Mice intracerebrally implanted with prion-contaminated stainless steel wires treated with ozone gas or vaporized hydrogen peroxide developed prion disease later than those implanted with control prion-contaminated stainless steel wires, indicating that ozone gas and vaporized hydrogen peroxide could reduce prion infectivity on wires. Incubation times were further elongated in mice implanted with prion-contaminated stainless steel wires treated with ozone gas-mixed vaporized hydrogen peroxide, indicating that ozone gas mixed with vaporized hydrogen peroxide reduces prions on these wires more potently than ozone gas or vaporized hydrogen peroxide. These results suggest that ozone gas mixed with vaporized hydrogen peroxide might be more useful for prion sterilization than ozone gas or vaporized hydrogen peroxide alone.