Vapor Phase Hydrogen Peroxide Research Articles

Development and Validation of a Customized Amplex UltraRed Assay for Sensitive Hydrogen Peroxide Detection in Pharmaceutical Water.

For clean-room technologies such as isolators and restricted access barrier systems (RABS), decontamination using hydrogen peroxide (H2O2) is increasingly attractive to fulfill regulatory requirements. Several approaches are currently used, ranging from manual wipe disinfection to vapor phase hydrogen peroxide (VPHP) or automated nebulization sanitization. Although the residual airborne H2O2 concentration can be easily monitored, detection of trace H2O2 residues in filled products is rather challenging. To simulate the filling process in a specific clean room, technical runs with water for injection (WfI) are popular. Thus, the ability to detect traces of H2O2 in water is an important prerequisite to ensure a safe and reliable use of H2O2 for isolator or clean room decontamination. The objective of this study was to provide a validated quantitative, fluorometric Amplex UltraRed assay, which satisfies the analytical target profile of quantifying H2O2 in WfI at low nanomolar to low micromolar concentrations (ppb range) with high accuracy and high precision. The Amplex UltraRed technology provides a solid basis for this purpose; however, no commercial assay kit that fulfills these requirements is available. Therefore, a customized Amplex UltraRed assay was developed, optimized, and validated. This approach resulted in an assay that is capable of quantifying H2O2 in WfI selectively, sensitively, accurately, precisely, and robustly. This assay is used in process development and qualification approaches using WfI in H2O2-decontaminated clean rooms and isolators.

Effect of surface modification on silica supported Ti catalysts for cyclohexene oxidation with vapor-phase hydrogen peroxide.

Surface modification via grafting of organic moieties on a Lewis acid catalyst (silica supported Ti catalyst, Ti-SiO2) alters the activation of H2O2 in vapor-phase cyclohexene epoxidation. Grafting a fluorous group (1H,1H-perfluoro-octyl) suppresses activity of Ti-SiO2. Conversely, grafting either a nonpolar group (octyl) or a polar aprotic group (triethylene glycol monomethyl ether) enhances rates and shifts selectivity toward trans-1,2-cyclohexanediol.

An Investigation of the Visual Impact of the Combined Exposure to Residual Cleaning Agents and Vaporized Hydrogen Peroxide on Materials used in Barrier Systems

Vaporized Hydrogen Peroxide (vapor-phase hydrogen peroxide, vH₂O₂) treatment is the main approach for sporicidal surface bio-decontamination in restricted access barrier systems and isolators. Prior to vH₂O₂ exposure, surfaces are cleaned to prepare the barrier system for the decontamination cycle, removing surface residues that could impede the cycles effectiveness. The presence of residual cleaning agents alongside vH₂O₂ exposure could potentially impact the integrity and longevity of materials, necessitating a comprehensive understanding of these interactions. To gain more knowledge about the influence of cleaning agents and vH₂O₂, various materials were exposed to a combination of cleaning agents and vH₂O₂ in order to visually assess the interaction. Introduction: Vaporized Hydrogen Peroxide has emerged as a valuable tool for bio-decontamination due to its ability to efficiently eliminate a wide range of microorganisms, including bacteria, viruses, and spores [1]. The penetration of vH₂O₂ is limited, so surfaces are cleaned to remove contaminants that may interfere with vH₂O₂ penetration and effectiveness prior to vH₂O₂ exposure. While studies have investigated the compatibility of materials with vH₂O₂ or cleaning agents alone [2,3], the interactions between residual cleaning agents and vH₂O₂ have received limited attention until now. Residual cleaning agents might persist even after thorough rinsing, potentially influencing the interaction of the vapour phase gas with materials. Reactive components within cleaning agents could react with vH₂O₂, probably leading to material deterioration, discoloration, or altered mechanical properties. Additionally, accumulated residues within surface microstructures might hinder vH₂O₂ diffusion, thus impacting its efficacy. Investigating these combined effects is pivotal to prevent unintended material outcomes during decontamination processes.

Ridding the World of 'Rogues': Improving Vapor Phase H2O2 Sterilization and Decontamination Processes.

This publication reviews the reported 'rogue' behavior of biological indicators used for vapor phase hydrogen peroxide processes with attention to the aspects of BI design / configuration to identify factors which may contribute to the reported greater variance in resistance. The contributing factors are reviewed with respect to the unique circumstances of a vapor phase process that adds challenges to H2O2 delivery to the spore challenge. The numerous complexities of H2O2 vapor phase processes are described as these contribute to the difficulties encountered. The paper includes specific recommendations for changes to the biological indicator configurations in use and the vapor process to reduce the incidence of rogues.

Cobalt Doped SnO2 Thin Film for Detection of Vapor Phase Hydrogen Peroxide

A technology was developed for manufacturing solid-state semiconductor sensor sensitive to hydrogen peroxide vapors. Gas sensitive nanostructured films made of doped metal oxide SnO2<Co> were manufactured by the high-frequency magnetron sputtering method. The chemical composition of prepared SnO2<Co> targets was analyzed and the thickness of the deposited doped metal oxide film was measured. The morphology of the deposited Co-doped SnO2 film was studied by scanning electron microscopy. The gas sensing characteristics to the different concentrations of hydrogen peroxide vapors at various operating temperatures were also studied. The Co-doped SnO2 sensor showed enough sensitivity to very low concentration of hydrogen peroxide vapors (875 ppb) at the operating temperature of 100 °C. The SnO2<Co> based sensor can be successfully used in medical diagnostic apparatus for determining low concentration of hydrogen peroxide vapors in exhaled air.

Strap Performance of N95 Filtering Facepiece Respirators After Multiple Decontamination Cycles

The Battelle Critical Care Decontamination System™ (CCDS™) decontaminates N95 filtering facepiece respirators (FFRs) using vapor phase hydrogen peroxide (VPHP) for reuse when there is a critical supply shortage. The Battelle CCDS received an Emergency Use Authorization (EUA) from the US Food and Drug Administration (FDA) in March 2020. This research focused on evaluating the mechanical properties of the straps as an indicator of respirator fit. The objective was to characterize the load generated by the straps following up to 20 don/doff and decontamination cycles in Battelle’s CCDS. In general, the measured loads at 50 and 100% strains after 20 cycles were similar (±15%) to the as-received controls. Qualitatively, reductions in the load may be associated with loss of elasticity in the straps, potentially reducing the ability to obtain a proper fit. However, small changes in strap elasticity may not affect the ability to obtain a proper fit given the potential for variation in strap length and positioning on the head. Regardless, prior to reusing a N95 respirator, it is important to complete a visual inspection to ensure it is not damaged, malformed, or soiled. If so, it is recommended to discard the respirator and use a different one. Similarly, the respirator should be discarded if the wearer cannot obtain a proper fit during the user seal check.

Inactivation of Murine Norovirus on Fruit and Vegetable Surfaces by Vapor Phase Hydrogen Peroxide

Vapor phase hydrogen peroxide (H2O2) can be utilized to inactivate murine norovirus (MNV), a surrogate of human norovirus, on surface areas. However, vapor phase H2O2 inactivation of virus on fruits and vegetables has not been characterized. In this study, MNV was used to determine whether vaporized H2O2 inactivates virus on surfaces of various fruits and vegetables (apples, blueberries, cucumbers, and strawberries). The effect of vapor phase H2O2 decontamination was investigated with two application systems. Plaque assays were performed after virus recovery from untreated and treated fresh produce to compare the quantity of infective MNV. The Mann-Whitney U test was applied to the test results to evaluate the virus titer reductions of treated food samples, with significance set at P ≤ 0.05. The infective MNV populations were significantly reduced on smooth surfaces by 4.3 log PFU (apples, P < 0.00001) and 4 log PFU or below the detection limit (blueberries, P = 0.0074) by treatment with vapor phase H2O2 (60 min, maximum of 214 ppm of H2O2). Similar treatments of artificially contaminated cucumbers resulted in a virus titer reduction of 1.9 log PFU. Treatment of inoculated strawberries resulted in 0.1- and 2.8-log reductions of MNV. However, MNV reduction rates on cucumbers (P = 0.3809) and strawberries (P = 0,7414) were not significant. Triangle tests and color measurements of untreated and treated apples, cucumbers, blueberries, and strawberries revealed no differences in color and consistency after H2O2 treatment. No increase of the H2O2 concentration in treated fruits and vegetables compared with untreated produce was observed. This study reveals for the first time the conditions under which vapor phase H2O2 inactivates MNV on selected fresh fruit and vegetable surfaces.

A Model of Prefilled Syringes Exposure to Vapor Phase Hydrogen Peroxide (VPHP).

A model was developed that can be used to predict how hydrogen peroxide (H2O2) transfers into a liquid drug product that is exposed to vapor phase hydrogen peroxide (VPHP). This model accounts for fluid flow in both the gas and liquid phases as well as the diffusion and convection mechanisms of mass transfer using the first principles of engineering to predict the amount of H2O2 that will transfer from the gas to the liquid phase considering a given geometrical system and surrounding conditions. The model was used to investigate how much space is needed in a given container to eliminate convective mass transfer and to create a balance between mass transfer and the air/liquid interface for oxidation-sensitive products in cartridges or vials being filled in an isolator. Experimental results compared well with model predictions. A no-slip boundary condition between the gas and liquid phases was used for the model, which was especially important for the full syringes where convective mass transport predominated. This model may be used to evaluate isolator designs for filling oxidation-sensitive products utilizing the correlation between spiking studies and VPHP uptake to minimize the uptake studies required. It could also be used to inform the design of containers that would minimize the potential for VPHP uptake. For the geometry tested here, it was demonstrated that convection only occurs near the top few millimeters of the container. If the fill level is lower, as it would be for a syringe, the diffusion mechanism of transfer predominates and the rate of transfer of H2O2 is much slower. The balance between mass transfer by convection and diffusion should be a consideration in the design of the system to be filled.

Vapor-Phase Hydrogen Peroxide Uptake by Silicone Tubing and Primary Packaging Components during Protein Drug Product Aseptic Filling: Impact of Pretreatment and Sterilization Process.

In the vapor-phase hydrogen peroxide (VPHP)-sanitized environment, VPHP uptake by product-contacting components could eventually lead to undesired oxidation of biological drug products. Silicone tubing and primary packaging materials are prominent examples of such product-contacting surfaces that are typically processed/sterilized prior to use. This study investigated the VPHP-uptake tendency of these components and how their respective processing/sterilization methods affect the uptake behaviors. Silicone tubing that was sterilized via autoclave or gamma irradiation exhibited different VPHP uptake patterns-decreased uptake rates post autoclaving vs. increased uptake rates post gamma irradiation. The reduced uptake tendency of autoclaved tubing is maintained for 14 days after sterilization, whereas the uptake tendency of irradiated tubing was mostly reversed to normal levels 1 month after irradiation. Empty glass vials adsorbed hydrogen peroxide via the diffusion of VPHP into the vial with high vial-to-vial variability. Vial pretreatment (i.e., depyrogenation) and surface hydrophilicity/hydrophobicity impacted the uptake tendency. Stoppers and empty syringes also adsorbed hydrogen peroxide but at a relatively low level. The uptake behavior of these components appeared to correlate with water levels at the surface (i.e., hydrophilicity). This study provides process development scientists and engineers an in-depth understanding of the VPHP uptake by critical product-contacting surfaces so that they can mitigate the impact on drug product quality.LAY ABSTRACT: This study investigated vapor-phase hydrogen peroxide (VPHP) absorption by biopharmaceutical drug products via VPHP uptake by critical product-contacting components during the aseptic manufacturing process with a focus on various pretreatments and processing of these components. Sterilization of silicone tubing by gamma irradiation or autoclaving resulted in different VPHP uptake profiles with different effect durations. Primary packaging components, such as vials, syringes, and stoppers, also showed different levels of VPHP uptake with surface hydrophilicity/hydrophobicity playing a critical role. These outcomes suggested that VPHP uptake is a complex phenomenon and should be carefully considered to minimize its impact on product quality. The approach and outcome of this study can benefit scientists and engineers who develop biological product manufacturing processes by providing an in-depth understanding of drug product process risks.

Stability Evaluation of Hydrogen Peroxide Uptake Samples from Monoclonal Antibody Drug Product Aseptically Filled in Vapor Phase Hydrogen Peroxide-Sanitized Barrier Systems: A Case Study.

During the manufacture of a monoclonal antibody drug product, which was aseptically filled within a vapor phase hydrogen peroxide-sanitized isolator, samples were taken to investigate the hydrogen peroxide uptake behaviors. Surprisingly, the samples had no detectable hydrogen peroxide (most results below the limit of detection). This finding was later attributed to hydrogen peroxide decomposition after the samples were stored frozen at -20°C for two weeks before testing. This case study highlights the criticality of storage conditions for hydrogen peroxide-containing samples and summarizes an investigation on hydrogen peroxide stability in water and in three monoclonal antibody solutions having a wide protein concentration range (30-200 mg/mL). Samples were stored at three temperatures (-70°C, -20°C, or 2-8°C) for up to 28 days to assess the impact of protein concentration and storage temperature on hydrogen peroxide decomposition rates. Hydrogen peroxide degraded slightly more rapidly with increasing protein concentration independent of storage condition. When stored at -20°C, hydrogen peroxide was least stable and degraded faster than when stored at 2-8°C. Hydrogen peroxide was most stable when the samples were stored at -70°C. Overall, this case study brings the hydrogen peroxide stability issue to the attention of process development scientists and engineers and offers a valuable lesson learned during process development.LAY ABSTRACT: The use of vapor phase hydrogen peroxide as a sanitizing agent for isolator and cleanroom decontamination has become common in recent years. Because of the potential impact of residual hydrogen peroxide on biopharmaceutical product quality, hydrogen peroxide uptake behaviors and mechanisms during the manufacturing process within these barriers need to be evaluated and understood. Samples taken from various small-scale and manufacturing-scale hydrogen peroxide uptake studies are often stored frozen before testing. This case study reports an important and interesting finding about hydrogen peroxide stability in samples collected for hydrogen peroxide uptake investigation, and it demonstrates the relationship between hydrogen peroxide stability and storage temperature, storage duration, and monoclonal antibody concentration. The approach and outcome of this study are expected to benefit scientists and engineers who develop biologic product manufacturing processes by providing a better understanding of drug product process challenges and appropriate sample storage.

Vapor Phase Hydrogen Peroxide Decontamination or Sanitization of an Isolator for Aseptic Filling of Monoclonal Antibody Drug Product-Hydrogen Peroxide Uptake and Impact on Protein Quality.

A monoclonal antibody drug product manufacturing process was transferred to a different production site, where aseptic filling took place within an isolator that was decontaminated (sanitized) using vapor phase hydrogen peroxide (VPHP). A quality-by-design approach was applied for study design to understand the impact of VPHP uptake on drug product quality. Both small-scale and manufacturing-scale studies were performed to evaluate the sensitivity of the monoclonal antibody to hydrogen peroxide (H2O2) and characterize VPHP uptake mechanisms in the filling process. The acceptable H2O2 uptake level was determined to be 100 ng/mL for the antibody in the H2O2 spiking study; protein oxidation was observed above this threshold. The most prominent sources of VPHP uptake were identified to be the silicone tubing assembly (associated with the peristaltic pumps) and open, filled vials. Silicone tubing, an effective depot to H2O2, absorbs VPHP during different stages of the filling process and transmits H2O2 into the drug product solution during filling interruptions. A small-scale isolator model, established to simulate manufacturing-scale conditions, was a useful tool in understanding H2O2 uptake in relation to tubing dimensions and VPHP concentration in the isolator air (or atmosphere). Although the tubing assembly had absorbed a substantial amount of VPHP during the decontamination phase, the majority of H2O2 could be removed during tubing cleaning and sterilization in the subsequent isolator aeration phase, demonstrating that H2O2 in the final drug product solution is primarily taken up from residual VPHP in the isolator during filling. Picarro sensor monitoring demonstrated that the validated VPHP aeration process generates reproducible residual VPHP profiles in isolator air, allowing small-scale studies to provide relevant recommendations on tubing size and interruption time limits for commercial manufacturing. The recommended process parameters were demonstrated to be acceptable and rendered no product quality impact in six consecutive manufacturing batches in the process validation campaign. Overall, this case study provides process development scientists and engineers an in-depth understanding of the VPHP process and a science-based approach to mitigating drug product quality impact.LAY ABSTRACT: While the use of vapor phase hydrogen peroxide as a sanitizing agent for isolator and cleanroom decontamination has gained popularity in recent years, its impact on product quality during aseptic manufacturing of biopharmaceutical drug products is yet to be fully understood. With this scope in mind, this case study offers a detailed account of defining process parameters and developing their operating ranges to ensure that the impact to product quality is minimized. Both small-scale and manufacturing-scale studies were performed to assess the sensitivity of a monoclonal antibody to hydrogen peroxide, to characterize hydrogen peroxide uptake sources and mechanisms, and to eventually define process parameters and their ranges critical for minimizing product quality impact. The approach and outcome of this study is expected to benefit scientists and engineers who develop biologic product manufacturing processes by providing a better understanding of drug product process challenges.

Methicillin-resistant Staphylococcus aureus decontamination: is ultraviolet radiation more effective than vapor-phase hydrogen peroxide?

Methicillin-resistant Staphylococcus aureus (MRSA) is an increasing problem for patients, clinicians, and epidemiologists. Patients risk MRSA colonization upon admittance in areas not properly disinfected. As high-level decontaminants, both ultraviolet (UV) radiation in the UV-C waveband as well as vapor-phase hydrogen peroxide (VHP) have been utilized to limit nosocomial infection cost and concomitant disease. In order to determine whether UV irradiation is more effective than VHP in the control and prevention of MRSA infection, 12 studies with N = 20 discrete data points were analyzed to determine efficacy based on log10 reductions in MRSA colonies on medically relevant surfaces reported in colony forming unit per unit area achieved within reported decontamination times. The search retrieved studies searching all databases of the Web of Science using the terms ‘hydrogen peroxide∗ AND MRSA∗’ and ‘ultraviolet AND MRSA∗’ within all time periods. A Student's t test determined a statistically significant difference in log reductions of MRSA achieved by each treatment (P = 0.0117), with a rejection of the null hypothesis of no statistical difference. A second t test determined no significant difference between reduction rates when decontamination time was factored into the analysis (P = 0.1701), supporting the null. Provisionally, the results indicate VHP having greater amounts of MRSA reduction than UV, with no difference between treatment reduction rates. However, each is considered effective in MRSA sterilization. Practical significance should be determined by biosafety officers and individual hospital policy as related to sterilization cutoffs. Further investigation and direct experimental comparisons are warranted considering the limitations of this study.

Evaluation of Novel Process Indicators for Rapid Monitoring of Hydrogen Peroxide Decontamination Processes.

Geobacillus stearothermophilus spores on stainless steel discs are routinely used as biological indicators for the validation of hydrogen peroxide bio-decontamination processes. Given ongoing concerns about the reliability and response time of biological indicators, we explored the potential for an enzyme-based approach to decontamination process evaluation. Thermostable adenylate kinase enzyme was coated onto a solid support and exposed to hydrogen peroxide vapour, in parallel with standard commercial 6-log biological indicators, during a series of vapour-phase hydrogen peroxide cycles in a flexible film isolator. The exposed biological indicators were enumerated to define the degree of kill at different time intervals and the results compared to the thermostable adenylate kinase values, as determined by measuring adenosine triphosphate produced by residual active enzyme. Both biological indicators and the thermostable adenylate kinase indicators exhibited a biphasic inactivation profile during the process. There was significant variance between individual cycles, with some cycles showing complete inactivation of the biological indicators to the limit of detection of the assay, within 6 min, whereas biological indicators in some cycles were inactivated at a time greater than 12 min. The log-kill of the biological indicators at intermediate time points were plotted and compared to the fully quantifiable measurements derived from the thermostable adenylate kinase indicators at the same time points. The results demonstrated very similar inactivation profiles for the enzyme and for the biological indicators, thus it was possible to define a relationship between relative light units measurement and biological indicator kill. This indicates that it is possible to use thermostable adenylate kinase measurement as a direct measure of vapour-phase hydrogen peroxide bio-decontamination performance, expressed in terms of log reduction. Because thermostable adenylate kinase measurement can be achieved within a few minutes of vapour-phase hydrogen peroxide cycle completion, compared with a minimum of 7 days for the evaluation of biological indicator growth, this offers a potentially valuable tool for rapid vapour-phase hydrogen peroxide bio-decontamination cycle development and subsequent re-qualification.LAY ABSTRACT: Pharmaceutical product manufacture is performed in controlled cleanroom and closed chamber environments (isolators) to reduce the risk of contamination. These environments undergo regular decontamination to control microbial contamination levels, using a range of methods, one of which is to vaporize hydrogen peroxide (a chemical disinfectant) into a gas or an aerosol and disperse it throughout the environment, killing any microorganisms present. Biological indicators, which consist of a small steel coupon carrying a population of bacterial spores that are more resistant to hydrogen peroxide than are most microorganisms, are placed within the environment, and then tested for growth following treatment to ensure the process was effective. Confirmation of growth/no growth (and therefore hydrogen peroxide cycle efficacy) can take up to 7 days, which significantly increases time and cost of developing and confirming cycle efficacy. This study tests whether a new technology which uses a robust enzyme, thermostable adenylate kinase, could be used to predict biological indicator growth. The study shows this method can be used to confirm hydrogen peroxide cycle efficacy, by predicting whether the BI is killed at a specific time point or not and results are obtained in a few minutes rather than 7 days. This potentially offers significant time and cost benefits.

Kinetic Modeling of Methionine Oxidation in Monoclonal Antibodies from Hydrogen Peroxide Spiking Studies.

When isolator technology is applied to biotechnology drug product fill-finish process, hydrogen peroxide (H2O2) spiking studies for the determination of the sensitivity of protein to residual peroxide in the isolator can be useful for assessing a maximum vapor phase hydrogen peroxide (VPHP) level. When monoclonal antibody (mAb) drug products were spiked with H2O2, an increase in methionine (Met 252 and Met 428) oxidation in the Fc region of the mAbs with a decrease in H2O2 concentration was observed for various levels of spiked-in peroxide. The reaction between Fc-Met and H2O2 was stoichiometric (i.e., 1:1 molar ratio), and the reaction rate was dependent on the concentrations of mAb and H2O2. The consumption of H2O2 by Fc-Met oxidation in the mAb followed pseudo first-order kinetics, and the rate was proportional to mAb concentration. The extent of Met 428 oxidation was half of that of Met 252, supporting that Met 252 is twice as reactive as Met 428. Similar results were observed for free L-methionine when spiked with H2O2. However, mAb formulation excipients may affect the rate of H2O2 consumption. mAb formulations containing trehalose or sucrose had faster H2O2 consumption rates than formulations without the sugars, which could be the result of impurities (e.g., metal ions) present in the excipients that may act as catalysts. Based on the H2O2 spiking study results, we can predict the amount Fc-Met oxidation for a given protein concentration and H2O2 level. Our kinetic modeling of the reaction between Fc-Met oxidation and H2O2 provides an outline to design a H2O2 spiking study to support the use of VPHP isolator for antibody drug product manufacture. Isolator technology is increasing used in drug product manufacturing of biotherapeutics. In order to understand the impact of residual vapor phase hydrogen peroxide (VPHP) levels on protein product quality, hydrogen peroxide (H2O2) spiking studies may be performed to determine the sensitivity of monoclonal antibody (mAb) drug products to residual peroxide in the isolator. In this study, mAbs were spiked with H2O2; an increase in methionine (Met) oxidation of the mAbs with a decrease in H2O2 concentration was observed for various levels of spiked-in peroxide. The reaction between Met and H2O2 was 1:1, and its rate was dependent on mAb and H2O2 concentrations. Consumption of H2O2 by Met followed pseudo first-order kinetics; the rate was proportional to mAb concentration. Formulations containing trehalose or sucrose had faster consumption rates than formulations without the sugars, which could be due to excipient impurities. Based on H2O2 spiking study results, we can predict the amount of Met oxidation for a given mAb concentration and H2O2 level. Our modeling of the reaction between Fc-Met oxidation and H2O2 provides an outline to design a H2O2 spiking study that supports using VPHP isolators during manufacture of mAb products.

과산화수소 증기를 이용한 유사화학작용제의 제독

과산화수소 증기는 기존 염소계열의 멸균제에 비해 부식성이 낮아 제약 및 의료 분야의 실내멸균제로 사용되며, 암모니아 가스 추가 시 화학작용제의 제독성능이 있다고 알려져 있다. 본 연구에서는 과산화수소 증기를 이용하여 HD, GD, VX의 유사작용제인 CEPS, DFP, dimethoate 등에 대한 제독효율을 확인하였다. 이를 위해 자체 구성한 과산화수소 기화장치에서 발생시킨 증기를 제독챔버에 주입하여 반응시간을 유지하였다. 제독 후 잔류물을 GC/MS로 분석한 후 제독효율을 계산하였고, 각각의 유사작용제에 대한 반응 생성물을 통해서 화학작용제의 반응 메카니즘과 유사함을 확인하였다. 실험결과 CEPS는 30%의 상대습도에서 60분의 반응시간에 완전제독 되었고, 암모니아 가스 주입의 동반하에서 DFP는 30분, dimethoate는 150분의 반응시간에 완전제독되었다. Vapor-phase hydrogen peroxide(VPHP) has been used as a sterilant in the field of medical and pharmaceutical application due to low corrosive than chlorine contained sterilant. In addition, it is well known that VPHP is effective for decontamination of chemical warfare agents by adding ammonia gas. In this study, the decontamination efficiency was confirmed about CEPS, DFP and dimethoate as simulants of HD, GD and VX using VPHP respectively. For this purpose, VPHP generated from self configured device was injected into decontamination chamber and maintained for reaction time. After the decontamination, the residues are analyzed by GC/MS and decontamination efficiency was calculated. Through by-product for each simulants, the similarities in reaction mechanism of chemical warfare agents were confirmed. CEPS was completely decontaminated at 30% relative humidity within 60 min. By adding ammonia gas, DFP and dimethoate were completely decontaminated within 30 and 150 min respectively.

과산화수소 증기 시스템을 이용한 미생물 제독에 관한 연구

Objectives: Effectiveness and conditions of vapor-phase hydrogen peroxide (VPHP) system on decontamination of Geobacillus stearothermophilus(GS) spores, Escherichia coli (E.coli) and Enterobacteria phage felix01 (felix01) were determined. Methods: The VPHP system was designed to vaporize 35% (w/w) solution of hydrogen peroxide, continuously to inject and withdraw VPHP. The system and VHP 1000ED (Steris) were operated such that dehumidification and conditioning were initiated without samples in the chamber. Then the samples were loaded into and removed. Coupons (glass, anodizing, silicon, viton) with GS spores (<TEX>$1{\times}10^6$</TEX> colony forming unit/mL [CFU/mL]), E.coli (<TEX>$1{\times}10^7$</TEX> CFU/mL) and felix01 (<TEX>$1{\times}10^7$</TEX> plaque forming unit/mL[PFU/mL]), and Biological Indicator (BI) with GS spores (<TEX>$1{\times}10^6$</TEX> CFU/mL) on stainless steel coupons were used. The tested samples were sonicated and vortexed, and then were plated for enumeration, followed by incubation at <TEX>$55^{\circ}C$</TEX>, 24 hr for GS spores, and at <TEX>$37^{\circ}C$</TEX>, 24 hr for E.coli and felix01. BI analysis in broth culture was only qualitative. Results: The efficacy of the VPHP system on decontamination was almost equivalent to that of VHP 1000ED. The conditions for complete decontamination with the VPHP system was as follows: concentration; 700~450 ppm, relative humidity; approximately 55%, and temperature; <TEX>$34{\sim}32^{\circ}C$</TEX>. When comparing the decontamination efficiency among different kinds of coupons, glass was the most effective, however, all kinds of coupons were decontaminated completely after 60 min exposure in both systems. Conclusion: The VPHP system can be recommended as an alternative system for traditional system using ethylene oxide, formaldehyde or chlorine dioxide.

Degradation of biologically active substances by vapor-phase hydrogen peroxide

We have examined the potential of vapor-phase hydrogen peroxide (VPHP) for degradation of 21 structurally different pharmaceutical substances. Our results show that VPHP can be used to degrade pharmaceuticals, but it was not universally applicable to all the drugs tested. Structural analysis revealed a significant correlation of the molecular structure of a compound with its susceptibility to VPHP. Tertiary amino groups seem to be the initiation centers, although the overall susceptibility of a substance depends on other factors also. Several tested substances underwent significant structural changes, suggesting a possible decrease in their biological activity. As far as we are aware, this is one of the first reports of application of VPHP to the decontamination of hazardous chemicals.

Insights into the Extremotolerance ofAcinetobacter radioresistens50v1, a Gram-Negative Bacterium Isolated from the Mars Odyssey Spacecraft

The microbiology of the spacecraft assembly process is of paramount importance to planetary exploration, as the biological contamination that can result from remote-enabled spacecraft carries the potential to impact both life-detection experiments and extraterrestrial evolution. Accordingly, insights into the mechanisms and range of extremotolerance of Acinetobacter radioresistens 50v1, a Gram-negative bacterium isolated from the surface of the preflight Mars Odyssey orbiter, were gained by using a combination of microbiological, enzymatic, and proteomic methods. In summary, A. radioresistens 50v1 displayed a remarkable range of survival against hydrogen peroxide and the sequential exposures of desiccation, vapor and plasma phase hydrogen peroxide, and ultraviolet irradiation. The survival is among the highest reported for non-spore-forming and Gram-negative bacteria and is based upon contributions from the enzyme-based degradation of H(2)O(2) (catalase and alkyl hydroperoxide reductase), energy management (ATP synthase and alcohol dehydrogenase), and modulation of the membrane composition. Together, the biochemical and survival features of A. radioresistens 50v1 support a potential persistence on Mars (given an unintended or planned surface landing of the Mars Odyssey orbiter), which in turn may compromise the scientific integrity of future life-detection missions.

Use of hydrogen peroxide as a biocide: new consideration of its mechanisms of biocidal action

Hydrogen peroxide is extensively used as a biocide, particularly in applications where its decomposition into non-toxic by-products is important. Although increasing information on the biocidal efficacy of hydrogen peroxide is available, there is still little understanding of its biocidal mechanisms of action. This review aims to combine past and novel evidence of interactions between hydrogen peroxide and the microbial cell and its components, while reflecting on alternative applications that make use of gaseous hydrogen peroxide. It is currently believed that the Fenton reaction leading to the production of free hydroxyl radicals is the basis of hydrogen peroxide action and evidence exists for this reaction leading to oxidation of DNA, proteins and membrane lipids in vivo. Investigations of DNA oxidation suggest that the oxidizing radical is the ferryl radical formed from DNA-associated iron, not hydroxyl. Investigations of protein oxidation suggest that selective oxidation of certain proteins might occur, and that vapour-phase hydrogen peroxide is a more potent oxidizer of protein than liquid-phase hydrogen peroxide. Few studies have investigated membrane damage by hydrogen peroxide, though it is suggested that this is important for the biocidal mechanism. No studies have investigated damage to microbial cell components under conditions commonly used for sterilization. Despite extensive studies of hydrogen peroxide toxicity, the mechanism of its action as a biocide requires further investigation.

Hydrogen Peroxide Vapor Penetration into Small Cavities during Low-Temperature Decontamination Cycles

The suitability of vapor-phase hydrogen peroxide for the decontamination of different-sized narrow cavities and complex geometrical structures were investigated in this paper. A cavity test block was used, and cavities made from different materials were tested with variable entrance heights and cavity depths. At the end of each cavity, biological indicators were exposed as a microbiological challenge for vapor-phase hydrogen peroxide penetration. Within this study, the test block with the biological indicators was subjected to different decontamination cycles in a production isolator. Inoculation level, cycle length, hydrogen peroxide, and water concentration were varied. The ratio of cavity entrance height to depth was found to be critical for decontamination success by biological indicators exposed inside the cavities. The higher the ratio, the more spores could be inactivated. Inactivation is also effected by exposure time and hydrogen peroxide concentration. The results indicate that the entrance height of the cavities should not be smaller than 6 mm and the cavity depth should not exceed 30 mm. If smaller cavities cannot be avoided, high peroxide concentration (800 ppm) and prolonged cycle times were shown to significantly enhance the penetration into dead-ended cavities under diffusive conditions.