investigating-detrimental-effects-low-pressure-plasma-sterilization

Investigating the Detrimental Effects of Low Pressure Plasma Sterilization on the Survival of <em>Bacillus subtilis</em> Spores Using Live Cell Microscopy

Plasma sterilization is a promising alternative to conventional sterilization methods for industrial, clinical, and spaceflight purposes. Low pressure ...

Ruhr-University Bochum

BIODECON - European project on plasma inactivation of bacteria and biomolecules.

The effect of cold low-pressure plasma treatment on neovascularization of a dermis substitute was evaluated in a mouse model.

Enhanced neovascularization of dermis substitutes via low-pressure plasma-mediated surface activation.

Sufficient induction of blood vessel ingrowth decisively influence transplant functionality. In this study, microvascular response to transplants of surface modified bone substitutes were assessed in vivo. The surface modification of allogenic bone substitutes (dehydrated human femoral head) was achieved in a double-conductive low-pressure gasplasma reactor (Ar(2) /O(2) , 13.65 MHz, 1,000 W, 5 Pa). The modified bone substitutes (n = 10) as well as untreated bone substitutes serving as controls (n = 10) were placed into the dorsal skinfold chamber of female balb/c mice (n = 10). Dynamic assessment of microcirculatory parameters was performed using intravital fluorescence microscopy during an implantation period of 10 days. The angiogenic response was found markedly accelerated in gasplasma-treated bone. Compared to untreated implants, the gasplasma-activated bone substitutes showed significantly higher microvascular density on days 5 and 10. The quantification of the microvascular diameters, red blood cell velocity, and microvascular permeability displayed stable perfusion and vascular integrity of the newly developed blood vessels throughout the 10-day observation period. The surface activation via cold low-pressure glow discharge gasplasma supports the vascular integration of allogenic bone by earlier induction of the angiogenesis.

Surface modification by glow discharge gasplasma treatment improves vascularization of allogenic bone implants.

A special focus area of planetary protection is the monitoring, control, and reduction of microbial contaminations that are detected on spacecraft components and hardware during and after assembly. In this study, wild-type spores of Bacillus pumilus SAFR-032 (a persistent spacecraft assembly facility isolate) and the laboratory model organism B. subtilis 168 were used to study the effects of low-pressure plasma, with hydrogen alone and in combination with oxygen and evaporated hydrogen peroxide as a process gas, on spore survival, which was determined by a colony formation assay. Spores of B. pumilus SAFR-032 and B. subtilis 168 were deposited with an aseptic technique onto the surface of stainless steel screws to simulate a spore-contaminated spacecraft hardware component, and were subsequently exposed to different plasmas and hydrogen peroxide conditions in a very high frequency capacitively coupled plasma reactor (VHF-CCP) to reduce the spore burden. Spores of the spacecraft isolate B. pumilus SAFR-032 were significantly more resistant to plasma treatment than spores of B. subtilis 168. The use of low-pressure plasma with an additional treatment of evaporated hydrogen peroxide also led to an enhanced spore inactivation that surpassed either single treatment when applied alone, which indicates the potential application of this method as a fast and suitable way to reduce spore-contaminated spacecraft hardware components for planetary protection purposes.

Utilization of low-pressure plasma to inactivate bacterial spores on stainless steel screws.

Novel decontamination technologies, including cold low-pressure plasma and blue light (400 nm), are promising alternatives to conventional surface decontamination methods. However, the standardization of the assessment of such sterilization processes remains to be accomplished. Bacterial endospores of the genera Bacillus and Geobacillus are frequently used as biological indicators (BIs) of sterility. Ensuring standardized and reproducible BIs for reliable testing procedures is a significant problem in industrial settings. In this study, an electrically driven spray deposition device was developed, allowing fast, reproducible, and homogeneous preparation of Bacillus subtilis 168 spore monolayers on glass surfaces. A detailed description of the structural design as well as the operating principle of the spraying device is given. The reproducible formation of spore monolayers of up to 5 × 10(7) spores per sample was verified by scanning electron microscopy. Surface inactivation studies revealed that monolayered spores were inactivated by UV-C (254 nm), low-pressure argon plasma (500 W, 10 Pa, 100 standard cubic cm per min), and blue light (400 nm) significantly faster than multilayered spores were. We have thus succeeded in the uniform preparation of reproducible, highly concentrated spore monolayers with the potential to generate BIs for a variety of nonpenetrating surface decontamination techniques.

Improvement of Biological Indicators by Uniformly Distributing Bacillus subtilis Spores in Monolayers To Evaluate Enhanced Spore Decontamination Technologies.

A new technology to the pharmaceutical field is presented: surface decontamination by plasmas The technology is comparable to established barrier systems like e-beam, volatile hydrogen peroxide, or radiation inactivation of microbiological contaminations. This plasma technology is part of a fully automated and validated syringe filling line at a major pharmaceutical company and is in production operation. Incoming pre-sterilized syringe containers ("tubs") are processed by plasma, solely on the outside, and passed into the aseptic filling isolator upon successful decontamination. The objective of this article is to present the operating principles and develop and establish a validation routine on the basis of standard commercial biological indicators. Their decontamination efficacies are determined and correlated to the actual inactivation efficacy on the pharmaceutical packaging material.The reference setup is explained in detail and a short presentation of the cycle development and the relevant plasma control parameters is given, with a special focus on the in-process monitor determining the cycle validity. Different microbial inactivation mechanisms are also discussed and evaluated for their contribution and interaction to enhance plasma decontamination. A material-dependent inactivation behavior was observed. In order to be able to correlate the tub surface inactivation of Geobacillus stearothermophilus endospores to metallic biological indicators, a comparative study was performed. Through consistently demonstrating the linear inactivation behavior between the different materials, it becomes possible to develop an effective and time-saving validation scheme.

Plasma Decontamination: A Case Study on Kill Efficacy of Geobacillus stearothermophilus Spores on Different Carrier Materials.

Identification and synthesis of intramolecularly donor-stabilized aluminium(III) complexes, which contain a 3-(dimethylamino)propyl (DMP) ligand, as novel atomic layer deposition (ALD) precursors has enabled the development of new and promising ALD processes for Al2 O3 thin films at low temperatures. Key for this promising outcome is the nature of the ligand combination that leads to heteroleptic Al complexes encompassing optimal volatility, thermal stability and reactivity. The first ever example of the application of this family of Al precursors for ALD is reported here. The process shows typical ALD like growth characteristics yielding homogeneous, smooth and high purity Al2 O3 thin films that are comparable to Al2 O3 layers grown by well-established, but highly pyrophoric, trimethylaluminium (TMA)-based ALD processes. This is a significant development based on the fact that these compounds are non-pyrophoric in nature and therefore should be considered as an alternative to the industrial TMA-based Al2 O3 ALD process used in many technological fields of application.

Unearthing [3-(Dimethylamino)propyl]aluminium(III) Complexes as Novel Atomic Layer Deposition (ALD) Precursors for Al2 O3 : Synthesis, Characterization and ALD Process Development.

Article	Year
BIODECON - European project on plasma inactivation of bacteria and biomolecules. GMS Krankenhaushygiene interdisziplinar\| PubMed ID: 20204106	2008
Enhanced neovascularization of dermis substitutes via low-pressure plasma-mediated surface activation. Burns : journal of the International Society for Burn Injuries\| PubMed ID: 20510519	2010
Surface modification by glow discharge gasplasma treatment improves vascularization of allogenic bone implants. Journal of orthopaedic research : official publication of the Orthopaedic Research Society\| PubMed ID: 21381095	2011
Utilization of low-pressure plasma to inactivate bacterial spores on stainless steel screws. Astrobiology\| PubMed ID: 23768085	2013
Improvement of Biological Indicators by Uniformly Distributing Bacillus subtilis Spores in Monolayers To Evaluate Enhanced Spore Decontamination Technologies. Applied and environmental microbiology\| PubMed ID: 26801572	2016
Plasma Decontamination: A Case Study on Kill Efficacy of Geobacillus stearothermophilus Spores on Different Carrier Materials. PDA journal of pharmaceutical science and technology\| PubMed ID: 27020647	2016
Unearthing [3-(Dimethylamino)propyl]aluminium(III) Complexes as Novel Atomic Layer Deposition (ALD) Precursors for Al2 O3 : Synthesis, Characterization and ALD Process Development. Chemistry (Weinheim an der Bergstrasse, Germany)\| PubMed ID: 28665519	2017

Peter Awakowicz

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