This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science, ICT, and Future Planning (# 2015R1A2A2A01006446).

1. הכנת השטח ליצירת biofilm <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> חותכים 1 מ&quot;מ בעובי 304 צלחות נירוסטה לתוך שבבים (10 × 10 מ&quot;מ 2) עם חותך מכני. </li><li style=";text-align:right;direction:rtl"> בצע ניקוי קולי של שבבי אצטון, מתנול, ו ללא יונים (DI) ברצף מים במשך 10 דקות כל אחד. השתמש מיכל ממס עמיד, עשוי חומרים כגון זכוכית, להסיר זיהום אורגני. </li><li style=";text-align:right;direction:rtl"> שוטף את השבב עם מים זורמים DI במשך 3-5 שניות. </li><li style=";text-align:right;direction:rtl"> ייבש את השבב באמצעות זרימת גז N 2 למשך 3-5 שניות. </li></ol> 2. הכנת תרבית חיידקים <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> קח פ putida KT2440 (בתנאי בחביבות על ידי פרופ &#39;סונג קוק Lee, UNIST, דרום קוריאה) מניות מאוחסנים -80 ° C עמוק במקפיא. </li><li style=";text-align:right;direction:rtl"> להפשיר בטמפרטורת החדר לאחר 1 דקות, ואת השכבה העליונה של פתרון המניות קפוא הופך לבוץ. לטבול לולאה לתוך השכבה המומסת של פתרון המניות. </li><li style=";text-align:right;direction:rtl"> השתמש לולאה זה פס החיידקים על גבי לוריאצלחת -Bertani (LB) המכילה אגר 1.5%. </li><li style=";text-align:right;direction:rtl"> דגירה את הצלחת לילה ב C 30 ° לגדל את מושבות חיידקים. </li><li style=";text-align:right;direction:rtl"> פיק מושבה אחת מהצלחת באמצעות לולאה טריה. </li><li style=";text-align:right;direction:rtl"> לחסן 10 מ&quot;ל של מרק LB צינור חרוטי 50 מ&quot;ל עם לולאה המכילה את מושבת חיידקים אחת. </li><li style=";text-align:right;direction:rtl"> דגירה מרק חממת רעד במשך 16 שעות ב 30 מעלות צלזיוס, 160 סל&quot;ד. </li></ol> 3. היווצרות biofilm על פני השטח <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> תרים אחד של השבבי המוכן עם פינצטה לטבול אותם 70% אתנול 5 פעמים במשך 1-2 שניות כל אחד, כדי לעקר את פני השטח של כל שבב. ודא שבב מוחזק עם פינצטה במהלך הטבילה. </li><li style=";text-align:right;direction:rtl"> טובלים כל שבב במים DI autoclaved וב ברצף מרק LB, 5 פעמים במשך 1-2 שניות כל אחד, כדי להסיר אתנול הנותרים. </li><li style=";text-align:right;direction:rtl"> מניחים שבבי אלה צלחות תרבות 6 היטב עם 2 צ&#39;יפים 5 מ&quot;ל מרק LB לכל טוב. </li><li style=";text-align:right;direction:rtl"> לדלל את תרבית החיידקים עד הריכוז בדרגים מרק LB8 × 10 8 תאים / מ&quot;ל (צפיפות אופטית באורך גל 600 ננומטר: ~ 0.8). </li><li style=";text-align:right;direction:rtl"> לחסן כל טוב עם 50 μl של תרבות חיידקים המדוללת. </li><li style=";text-align:right;direction:rtl"> דגירת הצלחות ב 30 מעלות צלזיוס ללא רעד במשך 24 שעות עבור היווצרות של biofilms. </li></ol> 4. ניקוי תרסיס CO 2 <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> טובלים את שבבי-נוצר ביופילם ב 10 מ&quot;מ אמוניום אצטט חיץ (נדיפים) 5 פעמים להסיר מחוברת באופן רופף וחיידקים planktonic. </li><li style=";text-align:right;direction:rtl"> לייבש את השבבים הללו בתוך ארון בטיחות ביולוגית, שבו האוויר זורם במתינות. </li><li style=";text-align:right;direction:rtl"> מיד לאחר הייבוש, למקם שבב על המקום הטעינה, המהווה 20 מ&quot;מ מלוע CO 2 לאורך ציר של סילון. הטה את ציר הסילון לזווית 40 מעלות. </li><li style=";text-align:right;direction:rtl"> הגדר את לחצי הקיפאון של CO 2 ו- N 2 גז 5.3 מגפ&quot;ס ו -0.7 מגפ&quot;ס, בהתאמה, באמצעות רגולטורים בלחץ גז. </li><li style=";text-align:right;direction:rtl"> החל הסילון אירוסול על החלק המרכזי של השבב. אירוסולים לבן כולל CO מוצק 2 צריךלהיות גלוי. הפעל &quot;על&quot; שסתום סולנואיד עבור CO 2 למשך 5 שניות ולאחר מכן הפעל אותו &quot;off&quot; במשך 3 שניות (מחזור: סעיף 8) באמצעות מעת לעת מתג נשלט באופן ידני. אם טיהור חנקן צריכה לשמש, להדליק את שסתום סולנואיד עבור אספקה רציפה של N 2. </li><li style=";text-align:right;direction:rtl"> פנקו את שבבי עם CO 2 אירוסולים במשך 16, 40, ו -88 שניות עם ובלי הטיהורים חנקן. שמור שבבי ללא טיפול שולטת שלילית. </li></ol> ניתוח 5. עבור יעילות הסרה <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> הכן 1 כתם חומצה פלואורסצנטי ירוק מיקרומטר גרעין (גל עירור / פליטה: 480/500 ננומטר) במים DI להכתים תאים חיידקיים בשלט וצ&#39;יפס שטופלו בתרסיס. </li><li style=";text-align:right;direction:rtl"> מניחים את שבבי בתמיסה מכתים. </li><li style=";text-align:right;direction:rtl"> דגירה שבבי באינקובטור ללא אור על 37 מעלות צלזיוס למשך 30 דקות. </li><li style=";text-align:right;direction:rtl"> לאחר הדגירה, לשטוף בעדינות את השבבים עם מים זורמים DI להסיר צבע ניאון מוגזם. </li><li style=";text-align:right;direction:rtl"> ייבש את wi השבביזרימת N 2 גז ה. </li><li style=";text-align:right;direction:rtl"> קח קרינת תמונות מיקרוסקופיות של 5 שדות אקראיים של תצוגה (321 × 240 מיקרומטר 2) עבור כל שבב באמצעות מיקרוסקופ epifluorescence, עדשה 40X אובייקטיבית, מצלמת CCD. </li><li style=";text-align:right;direction:rtl"> השג את עוצמת הקרינה עבור כל תמונה באמצעות תוכנת עיבוד תמונה כגון ImageJ. ב ImageJ, השתמש בפונקצית &quot;רקע פחת&quot; בתפריט &quot;התהליך&quot;, ובחר &quot;צפיפות משולבת&quot; בחלון &quot;מדידות גדר&quot; בתפריט &quot;לנתח&quot;. האם &quot;המדידה&quot; בתפריט &quot;נתח&quot; כדי להשיג את עוצמת הקרינה. </li><li style=";text-align:right;direction:rtl"> חשבתי את היעילות ביופילם ההסרה פי הנוסחא הבאה: 100% × (אני שבבים מלאי - אני שבבי מטופלים) / (אני שבבים שליטים), שבו אני נמצא את עוצמת הקרינה חושב. </li><li style=";text-align:right;direction:rtl"> להשיג את הממוצע ויעילות הסרה וסטיות תקן. השתמש ב4 שבבי לפחות עבור כל מקרה. </li></ol>

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	<li>Jain, A., Gupta, Y., Agrawal, R., Khare, P., Jain, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biofilms+-+A+microbial+life+perspective:+A+critical+review.">Biofilms - A microbial life perspective: A critical review.</a> Crit. Rev. Ther. Drug. 24 (5), 393-443 (2007).</li><li>Bott, T. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biofouling+control+with+ultrasound.">Biofouling control with ultrasound.</a> Heat Transfer Eng. 21 (3), 43-49 (2000).</li><li>Meyer, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Approaches+to+prevention,+removal+and+killing+of+biofilms.">Approaches to prevention, removal and killing of biofilms.</a> Int. Biodeterior. Biodegradation. 51 (4), 249-253 (2003).</li><li>Hong, S. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+electric+currents+on+bacterial+detachment+and+inactivation.">Effect of electric currents on bacterial detachment and inactivation.</a> Biotechnol. Bioeng. 100 (2), 379-386 (2008).</li><li>Nandakumar, K., Obika, H., Utsumi, A., Ooie, T., Yano, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+laser+ablation+of+laboratory+developed+biofilms+using+an+Nd:YAG+laser+of+532+nm+wavelength.">In vitro laser ablation of laboratory developed biofilms using an Nd:YAG laser of 532 nm wavelength.</a> Biotechnol. Bioeng. 86 (7), 729-736 (2004).</li><li>Gibson, H., Taylor, J. H., Hall, K. E., Holah, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effectiveness+of+cleaning+techniques+used+in+the+food+industry+in+terms+of+the+removal+of+bacterial+biofilms.">Effectiveness of cleaning techniques used in the food industry in terms of the removal of bacterial biofilms.</a> J. Appl. Microbiol. 87 (1), 41-48 (1999).</li><li>Kang, M. Y., Jeong, H. W., Kim, J., Lee, J. W., Jang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Removal+of+biofilms+using+carbon+dioxide+aerosols.">Removal of biofilms using carbon dioxide aerosols.</a> J. Aerosol Sci. 41 (11), 1044-1051 (2010).</li><li>Cha, M., Hong, S., Kang, M. Y., Lee, J. W., Jang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gas-phase+removal+of+biofilms+from+various+surfaces+using+carbon+dioxide+aerosols.">Gas-phase removal of biofilms from various surfaces using carbon dioxide aerosols.</a> Biofouling. 28 (7), 681-686 (2012).</li><li>Dwidar, M., Hong, S., Cha, M., Jang, J., Mitchell, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combined+application+of+bacterial+predation+and+carbon+dioxide+aerosols+to+effectively+remove+biofilms.">Combined application of bacterial predation and carbon dioxide aerosols to effectively remove biofilms.</a> Biofouling. 28 (7), 671-680 (2012).</li><li>Cha, M., Hong, S., Lee, S. Y., Jang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Removal+of+different-age+biofilms+using+carbon+dioxide+aerosols.">Removal of different-age biofilms using carbon dioxide aerosols.</a> Biotechnol. Bioprocess Eng. 19 (3), 503-509 (2014).</li><li>Singh, R., Monnappa, A. K., Hong, S., Mitchell, R. J., Jang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+Carbon+Dioxide+Aerosols+on+the+Viability+of+Escherichia+coli+during+Biofilm+Dispersal.">Effects of Carbon Dioxide Aerosols on the Viability of Escherichia coli during Biofilm Dispersal.</a> Sci. Rep. 5, 13766 (2015).</li><li>Sherman, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+Dioxide+Snow+Cleaning.">Carbon Dioxide Snow Cleaning.</a> Particul. Sci.Technol. 25 (1), 37-57 (2007).</li></ol>

The authors declare that they have no competing financial interests.

Previously, we conducted optimization studies on CO2 gas pressure, jet angle, and distance to the solid surface in CO2 aerosol cleaning7. Unlike our previous studies, in the present study, a nitrogen purge was not included in the aerosol (Figure 1). Moreover, 304 stainless steel was used in this protocol, since it is one of the most common stainless steels and is widely used in the food industry. The polished surface is beneficial for fluorescence analysis because of a un...

Biofilms are complex bacterial community structures in which bacterial cells are embedded within self-produced matrices of extracellular polymeric substances, held together, and protected from the external environment. Biofilms can present a public health risk and cause economic losses because they can form on various surfaces, including medical implant materials and devices, food processing equipment, and heat exchangers. In fact, biofilms have been found to be associated with 65% of all bacterial infectious diseases in humans, according to the Centers for Disease Control and Prevention1.
Autoclaves and disinfectants such as chlorine have generally been used for the inactivation of biofilms. However, the use of an autoclave is limited for surfaces that can neither withstand high temperature steam nor be placed into the autoclave. Disinfectants are not suitable for surfaces sensitive to chemical treatment or prone to collecting toxic oxidation products2. In addition, the biofilm should not only be inactivated, but also removed in order to prevent the attachment of new cells onto the surface, thereby forming a new biofilm3. However, it is difficult to remove biofilms using methods based on viscous fluid shear because the flow velocity near the surface is almost zero and the shear force usually cannot overcome the adhesive forces of micron- and submicron-sized substances. Moreover, the biofilm matrix is known to act as a physical and chemical barrier1.
Many physical and mechanical techniques have been developed to remove biofilms from surfaces, including ultrasonic vibration1, electric currents4, laser irradiation5, and high-pressure water sprays6. Each technique has its own pros and cons. Ultrasonic vibration and electric current can be used to control biofilm formation; however, they require a particular configuration and conductive surfaces, respectively, requiring additional shear stress1, 4. Laser irradiation can be applied to a limited area and to hard surfaces; however, some live and dead cells remain on the surface5. High-pressure water sprays effectively remove biofilms; however, their high momentum can cause damage to soft substrates6.
Biofilm removal using CO2 aerosols has been previously proposed. It has shown promising results, with high removal efficiencies within a short time7-11. CO2 aerosols are generated by adiabatic expansion of a high-pressure CO2 gas through a nozzle, and they are applied to the surfaces contaminated with a biofilm. This cleaning technique utilizes the momentum transfer of solid CO2 particles and the solvent action of the melted CO2 liquids, followed by the aerodynamic shear force of the CO2 gas12. Compared with high-pressure N2 gas jets, CO2 aerosol jets at the same stagnation pressure are much more effective in removing E. coli biofilms7. Moreover, although the momentum of the solid CO2 that is delivered to the bacteria is considerably high, the momentum of the total aerosol jet applied to the solid surface is substantially lower than that of water jets. Therefore, damage-free cleaning is possible using this CO2 aerosol technique.
In this protocol, periodic jets of CO2 aerosols without nitrogen purges were used to remove Pseudomonas putida biofilms from a polished stainless steel surface. In fact, nitrogen purges have been used in many CO2 aerosol studies to increase the removal efficiency by reducing the moisture condensation generated during the cleaning, even though heating with a hot plate or infrared lamps and employing dry boxes have also been adopted12. The surface biofilm formation and the optimized cleaning procedures are described below. The removal efficiency was evaluated by measuring the fluorescence intensity of the biofilm on the surface.

<table><tbody><tr><td>304 stainless steel</td><td>Steelni&lt;br/&gt; (South Korea)</td><td></td><td>Polished and diced ones</td></tr><tr><td>Ultrasonic cleaner</td><td>Branson&lt;br/&gt; (USA)</td><td>5510E-DTH</td><td></td></tr><tr><td>Luria-Bertani (LB)</td><td>Becton, Dickinson and Company&lt;br/&gt; (USA)</td><td>244620</td><td>500 g</td></tr><tr><td>Agar</td><td>Becton, Dickinson and Company&lt;br/&gt; (USA)</td><td>214010</td><td>500 g</td></tr><tr><td>6-well culture plate</td><td>SPL Life Sciences&lt;br/&gt; (South Korea)</td><td>32006</td><td></td></tr><tr><td>Ammonium acetate buffer</td><td>Sigma-Aldrich&lt;br/&gt; (USA)</td><td>667404</td><td>10 mM</td></tr><tr><td>Dual gas unit</td><td>Applied Surface Technologies&lt;br/&gt; (USA)</td><td>K6-10DG</td><td>One nozzle for CO&lt;sub&gt;2&lt;/sub&gt; gas&lt;br/&gt; &amp;amp; 8 nozzles for N&lt;sub&gt;2&lt;/sub&gt; gas</td></tr><tr><td>SYTO9</td><td>Thermo Fissher Scientific&lt;br/&gt; (USA)</td><td>Invitrogen</td><td>Excitaion: 480 nm&lt;br/&gt; Emission: 500 nm</td></tr><tr><td>Epifluorescence microscope&amp;nbsp;</td><td>Nikon (Japan)</td><td>Eclipse 80i</td><td></td></tr><tr><td>40X objective lens</td><td>Nikon&lt;br/&gt; (Japan)</td><td>Plan Fluor</td><td>NA: 0.75</td></tr><tr><td>CCD camera&amp;nbsp;</td><td>Photometrics&lt;br/&gt; (USA)</td><td>Cool SNAP HQ2</td><td>Monochrome</td></tr></tbody></table>

biofilm removal using carbon dioxide aerosols without nitrogen purge

Biofilms can cause serious concerns in many applications. Not only can they cause economic losses, but they can also present a public health hazard. Therefore, it is highly desirable to remove biofilms from surfaces. Many studies on CO2 aerosol cleaning have employed nitrogen purges to increase biofilm removal efficiency by reducing the moisture condensation generated during the cleaning. However, in this study, periodic jets of CO2 aerosols without nitrogen purges were used to remove Pseudomonas putida biofilms from polished stainless steel surfaces. CO2 aerosols are mixtures of solid and gaseous CO2 and are generated when high-pressure CO2 gas is adiabatically expanded through a nozzle. These high-speed aerosols were applied to a biofilm that had been grown for 24 hr. The removal efficiency ranged from 90.36% to 98.29% and was evaluated by measuring the fluorescence intensity of the biofilm as the treatment time was varied from 16 sec to 88 sec. We also performed experiments to compare the removal efficiencies with and without nitrogen purges; the measured biofilm removal efficiencies were not significantly different from each other (t-test, p &gt; 0.55). Therefore, this technique can be used to clean various bio-contaminated surfaces within one minute.

אירוסולים 2 CO שימשו כדי להסיר את פ putida Biofilms מ SUS304 משטחים (איור 1). רוב המשטחים היו מכוסות עם ביופילם לאחר 24 שעות של צמיחה. רוב ביופילם הוסר באמצעות CO 2 אירוסולים (איור 2). כצפוי, איור 3 מראה על עלייה יעילה ביופילם הסרה כזמן טיפול א...

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Biofilm Removal Using Carbon Dioxide Aerosols without Nitrogen Purge

Biofilms on surfaces can be effectively and rapidly removed by using a periodic jet of carbon dioxide aerosols without a nitrogen purge.

הסרת biofilm באמצעות אירוסולים פחמן דו-חמצני ללא חנקן טהר

Biofilms can cause serious concerns in many applications. Not only can they cause economic losses, but they can also present a public health hazard. ...

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6.3K Views.  Ulsan National Institute of Science and Technology (UNIST). Biofilms on surfaces can be effectively and rapidly removed by using a periodic jet of carbon dioxide aerosols without a nitrogen purge.

Video: Biofilm Removal Using Carbon Dioxide Aerosols without Nitrogen Purge

Co-culture Models of Pseudomonas aeruginosa Biofilms Grown on Live Human Airway Cells

Bacterial biofilms have been associated with a number of different human diseases, but biofilm development has generally been studied on non-living surfaces. In this paper, we describe protocols for forming Pseudomonas aeruginosa biofilms on human airway epithelial cells (CFBE cells) grown in culture. In the first method (termed the Static Co-culture Biofilm Model), P. aeruginosa is incubated with CFBE cells grown as confluent monolayers on standard tissue culture plates. Although the bacterium is quite toxic to epithelial cells, the addition of arginine delays the destruction of the monolayer long enough for biofilms to form on the CFBE cells. The second method (termed the Flow Cell Co-culture Biofilm Model), involves adaptation of a biofilm flow cell apparatus, which is often used in biofilm research, to accommodate a glass coverslip supporting a confluent monolayer of CFBE cells. This monolayer is inoculated with P. aeruginosa and a peristaltic pump then flows fresh medium across the cells. In both systems, bacterial biofilms form within 6-8 hours after inoculation. Visualization of the biofilm is enhanced by the use of P. aeruginosa strains constitutively expressing green fluorescent protein (GFP). The Static and Flow Cell Co-culture Biofilm assays are model systems for early P. aeruginosa infection of the Cystic Fibrosis (CF) lung, and these techniques allow different aspects of P. aeruginosa biofilm formation and virulence to be studied, including biofilm cytotoxicity, measurement of biofilm CFU, and staining and visualizing the biofilm.

Co-culture Models of Pseudomonas aeruginosa Biofilms Grown on Live Human Airway Cells

This paper describes different methods of growing Pseudomonas aeruginosa biofilms on cultured human airway epithelial cells. These protocols can be adapted to study different aspects of biofilm formation, including visualization of the biofilm, staining of the biofilm, measuring the colony forming units (CFU) of the biofilm, and studying biofilm cytotoxicity.

Co-מודלים של תרבות Pseudomonas aeruginosa Biofilms גדל על תאים חיים Airway האדם

Bacterial biofilms have been associated with a number of different human diseases, but biofilm development has generally been studied on non-living ...

Immunology and Infection

Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high surface area microporous materials, such as metal-organic frameworks (MOFs), unique challenges present themselves for PECVD treatments. Herein the protocol for development of a MOF that was previously unstable to humid conditions is presented. The protocol describes the synthesis of Cu-BTC (also known as HKUST-1), the treatment of Cu-BTC with PECVD of perfluoroalkanes, the aging of materials under humid conditions, and the subsequent ammonia microbreakthrough experiments on milligram quantities of microporous materials. Cu-BTC has an extremely high surface area (~1,800 m2/g) when compared to most materials or surfaces that have been previously treated by PECVD methods. Parameters such as chamber pressure and treatment time are extremely important to ensure the perfluoroalkane plasma penetrates to and reacts with the inner MOF surfaces. Furthermore, the protocol for ammonia microbreakthrough experiments set forth here can be utilized for a variety of test gases and microporous materials.

Herein the procedures for plasma enhanced chemical vapor deposition of perfluoroalkanes on microporous materials such as metal-organic frameworks to enhance their stability and hydrophobicity are described. Furthermore, breakthrough testing of milligram quantities of samples is described in detail.

הכנת מסגרות מתכת אורגנית הידרופובי באמצעות פלזמה משופרת שיקוע הכימי של Perfluoroalkanes להסרת אמוניה

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high ...

Chemistry

Preparation of Biopolymer Aerogels Using Green Solvents

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers (gelatin, agar, cellulose), only recently have biomasses been recognized as an abundant source of chemically diverse macromolecules for functional aerogel materials. Biopolymer aerogels (pectin, alginate, chitosan, cellulose, etc.) exhibit both specific inheritable functions of starting biopolymers and distinctive features of aerogels (80-99% porosity and specific surface up to 800 m2/g). This synergy of properties makes biopolymer aerogels promising candidates for a wide gamut of applications such as thermal insulation, tissue engineering and regenerative medicine, drug delivery systems, functional foods, catalysts, adsorbents and sensors. This work demonstrates the use of pressurized carbon dioxide (5 MPa) for the ionic cross linking of amidated pectin into hydrogels. Initially a biopolymer/salt dispersion is prepared in water. Under pressurized CO2 conditions, the pH of the biopolymer solution is lowered to 3 which releases the crosslinking cations from the salt to bind with the biopolymer yielding hydrogels. Solvent exchange to ethanol and further supercritical CO2 drying (10 - 12 MPa) yield aerogels. Obtained aerogels are ultra-porous with low density (as low as 0.02 g/cm3), high specific surface area (350 - 500 m2/g) and pore volume (3 - 7 cm3/g for pore sizes less than 150 nm).

A new way for the production of biopolymer-based aerogels by carbon dioxide (CO2) induced gelation is shown. The technique utilizes pressurized carbon dioxide (5 MPa) for the production of biopolymer hydrogels and supercritical CO2 (12 MPa) to convert gels into aerogels. The only solvents needed besides CO2 are water and ethanol.

הכנת Aerogels biopolymer בעזרת ממיסים גרין

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers ...

Non-equilibrium Microwave Plasma for Efficient High Temperature Chemistry

A flowing microwave plasma based methodology for converting electric energy into internal and/or translational modes of stable molecules with the purpose of efficiently driving non-equilibrium chemistry is discussed. The advantage of a flowing plasma reactor is that continuous chemical processes can be driven with the flexibility of startup times in the seconds timescale. The plasma approach is generically suitable for conversion/activation of stable molecules such as CO2, N2 and CH4. Here the reduction of CO2 to CO is used as a model system: the complementary diagnostics illustrate how a baseline thermodynamic equilibrium conversion can be exceeded by the intrinsic non-equilibrium from high vibrational excitation. Laser (Rayleigh) scattering is used to measure the reactor temperature and Fourier Transform Infrared Spectroscopy (FTIR) to characterize in situ internal (vibrational) excitation as well as the effluent composition to monitor conversion and selectivity.

This article describes a flowing microwave reactor that is used to drive efficient non-equilibrium chemistry for the application of conversion/activation of stable molecules such as CO2, N2 and CH4. The goal of the procedure described here is to measure the in situ gas temperature and gas conversion.

פלזמה מיקרוגל לא שיווי משקל עבור כימיה יעילה טמפרטורה גבוהה

A flowing microwave plasma based methodology for converting electric energy into internal and/or translational modes of stable molecules with the purpose ...

Precision Milling of Carbon Nanotube Forests Using Low Pressure Scanning Electron Microscopy

A nanoscale fabrication technique appropriate for milling carbon nanotube (CNT) forests is described. The technique utilizes an environmental scanning electron microscope (ESEM) operating with a low pressure water vapor ambient. In this technique, a portion of the electron beam interacts with the water vapor in the vicinity of the CNT sample, dissociating the water molecules into hydroxyl radicals and other species by radiolysis. The remainder of the electron beam interacts with the CNT forest sample, making it susceptible to oxidation from the chemical products of radiolysis. This technique may be used to trim a selected region of an individual CNT, or it may be used to remove hundreds of cubic microns of material by adjusting ESEM parameters. The machining resolution is similar to the imaging resolution of the ESEM itself. The technique produces only small quantities of carbon residue along the boundaries of the cutting zone, with minimal effect on the native structural morphology of the CNT forest.

Low pressure scanning electron microscopy in a water vapor ambient is used to machine nanoscale to microscale features in carbon nanotube forests.

כרסום Precision של יערות Nanotube הפחמן באמצעות סריקה בלחץ נמוך למיקרוסקופיה אלקטרונית

A nanoscale fabrication technique appropriate for milling carbon nanotube (CNT) forests is described. The technique utilizes an environmental scanning ...

Engineering

Achieving Moderate Pressures in Sealed Vessels Using Dry Ice As a Solid CO2 Source

Herein is presented a general strategy to perform reactions under mild to moderate CO2 pressures with dry ice. This technique obviates the need for specialized equipment to achieve modest pressures, and can even be used to achieve higher pressures in more specialized equipment and sturdier reaction vessels. At the end of the reaction, the vials can be easily depressurized by opening at room temperature. In the present example CO2 serves as both a putative directing group as well as a way to passivate amine substrates, thereby preventing oxidation during the organometallic reaction. In addition to being easily added, the directing group is also removed under vacuum, obviating the need for extensive purification to remove the directing group. This strategy allows the facile &#947;-C(sp3)-H arylation of aliphatic amines and has the potential to be applied to a variety of other amine-based reactions.

Achieving Moderate Pressures in Sealed Vessels Using Dry Ice As a Solid CO2 Source

Here we present a protocol for performing reactions in simple reaction vessels under low-to-moderate pressures of CO2. The reactions can be performed in a variety of vessels simply by administering the carbon dioxide in the form of dry ice, without the need for costly or elaborate equipment or set-ups.

להשגת לחצים מתונה בכלי אטום באמצעות קרח יבש כמקור2 CO מוצק

Herein is presented a general strategy to perform reactions under mild to moderate CO2 pressures with dry ice. This technique obviates the need for ...

Encapsulating Cytochrome c in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity

Applications such as sensors, batteries, and fuel cells have been improved through the use of highly porous aerogels when functional compounds are encapsulated within the aerogels. However, few reports on encapsulating proteins within sol&#8211;gels that are processed to form aerogels exist. A procedure for encapsulating cytochrome c (cyt. c) in silica (SiO2) sol-gels that are supercritically processed to form bioaerogels with gas-phase activity for nitric oxide (NO) is presented. Cyt. c is added to a mixed silica sol under controlled protein concentration and buffer strength conditions. The sol mixture is then gelled and the liquid filling the gel pores is replaced through a series of solvent exchanges with liquid carbon dioxide. The carbon dioxide is brought to its critical point and vented off to form dry aerogels with cyt. c encapsulated inside. These bioaerogels are characterized with UV-visible spectroscopy and circular dichroism spectroscopy and can be used to detect the presence of gas-phase nitric oxide. The success of this procedure depends on regulating the cyt. c concentration and the buffer concentration and does not require other components such as metal nanoparticles. It may be possible to encapsulate other proteins using a similar approach making this procedure important for potential future bioanalytical device development.

Encapsulating Cytochrome c in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity

This procedure describes how to encapsulate cytochrome c (cyt. c) in silica (SiO2) sol-gels, process these gels to form bioaerogels, and use these bioaerogels to rapidly recognize nitric oxide (NO) through a gas-phase reaction. This type of protocol may aid in the future development of biosensors or other bioanalytical devices.

encapsulating ציטוכרום<em&gt; ג</em&gt; ב סיליקה אירוג&#39;ל Nanoarchitectures ללא מתכת חלקיקים תוך שמירת גז שלב פעילות ביולוגית

Applications such as sensors, batteries, and fuel cells have been improved through the use of highly porous aerogels when functional compounds are ...

Bioengineering

Microfluidic Fabrication Techniques for High-Pressure Testing of Microscale Supercritical CO2 Foam Transport in Fractured Unconventional Reservoirs

Pressure limitations of many microfluidic platforms have been a significant challenge in microfluidic experimental studies of fractured media. As a result, these platforms have not been fully exploited for direct observation of high-pressure transport in fractures. This work introduces microfluidic platforms that enable direct observation of multiphase flow in devices featuring surrogate permeable media and fractured systems. Such platforms provide a pathway to address important and timely questions such as those related to CO2 capture, utilization and storage. This work provides a detailed description of the fabrication techniques and an experimental setup that may serve to analyze the behavior of supercritical CO2 (scCO2) foam, its structure and stability. Such studies provide important insights regarding enhanced oil recovery processes and the role of hydraulic fractures in resource recovery from unconventional reservoirs. This work presents a comparative study of microfluidic devices developed using two different techniques: photolithography/wet-etching/thermal-bonding versus Selective Laser-induced Etching. Both techniques result in devices that are chemically and physically resistant and tolerant of high pressure and temperature conditions that correspond to subsurface systems of interest. Both techniques provide pathways to high-precision etched microchannels and capable lab-on-chip devices. Photolithography/wet-etching, however, enables fabrication of complex channel networks with complex geometries, which would be a challenging task for laser etching techniques. This work summarizes a step-by-step photolithography, wet-etching and glass thermal-bonding protocol and, presents representative observations of foam transport with relevance to oil recovery from unconventional tight and shale formations. Finally, this work describes the use of a high-resolution monochromatic sensor to observe scCO2 foam behavior where the entirety of the permeable medium is observed simultaneously while preserving the resolution needed to resolve features as small as 10 &#181;m.

Microfluidic Fabrication Techniques for High-Pressure Testing of Microscale Supercritical CO2 Foam Transport in Fractured Unconventional Reservoirs

This paper describes a protocol along with a comparative study of two microfluidic fabrication techniques, namely photolithography/wet-etching/thermal-bonding and Selective Laser-induced Etching (SLE), that are suitable for high-pressure conditions. These techniques constitute enabling platforms for direct observation of fluid flow in surrogate permeable media and fractured systems under reservoir conditions.

טכניקות ייצור מיקרו-נוזלים לבדיקות בלחץ גבוה של הובלת קצף CO2 סופר-קריטי בקנה מידה במאגרים לא קונבנציונליים סדוקים

Pressure limitations of many microfluidic platforms have been a significant challenge in microfluidic experimental studies of fractured media. As a ...

Anti-virulent Disruption of Pathogenic Biofilms using Engineered Quorum-quenching Lactonases

The rapid emergence of multi-drug resistant bacteria has accelerated the need for novel therapeutic approaches to counter life-threatening infections. The persistence of bacterial infection is often associated with quorum-sensing-mediated biofilm formation. Thus, the disruption of this signaling circuit presents an attractive anti-virulence strategy. Quorum-quenching lactonases have been reported to be effective disrupters of quorum-sensing circuits. However, there have been very few reports of the effective use of these enzymes in disrupting bacterial biofilm formation. This protocol describes a method to disrupt biofilm formation in a clinically relevant A. baumannii S1 strain through the use of an engineered quorum-quenching lactonase. Acinetobacter baumannii is a major human pathogen implicated in serious hospital-acquired infections globally and its virulence is attributed predominantly to its biofilm's tenacity. The engineered lactonase treatment achieved significant A. baumannii S1 biofilm reduction. This study also showed the possibility of using engineered quorum-quenching enzymes in future treatment of biofilm-mediated bacterial diseases. Lastly, the method may be used to evaluate the competency of promising quorum-quenching enzymes.

Quorum-quenching enzymes are anti-virulent and anti-bacterial options that can mitigate pathogenesis without risk of incurring resistance, by preventing the expression of virulence factors and genes associated with antibiotic resistance and biofilm formation. In this study, we report a method that demonstrates the efficacy of quorum-quenching enzymes in bacterial biofilm disruption.

שיבוש אנטי-ארסי של Biofilms פתוגניים באמצעות Lactonases תכנון הנדסי Quorum-מרווה

The rapid emergence of multi-drug resistant bacteria has accelerated the need for novel therapeutic approaches to counter life-threatening infections. The ...

Methodologies for Studying B. subtilis Biofilms as a Model for Characterizing Small Molecule Biofilm Inhibitors

This work assesses different methodologies to study the impact of small molecule biofilm inhibitors, such as D-amino acids, on the development and resilience of Bacillus subtilis biofilms. First, methods are presented that select for small molecule inhibitors with biofilm-specific targets in order to separate the effect of the small molecule inhibitors on planktonic growth from their effect on biofilm formation. Next, we focus on how inoculation conditions affect the sensitivity of multicellular, floating B. subtilis cultures to small molecule inhibitors. The results suggest that discrepancies in the reported effects of such inhibitors such as D-amino acids are due to inconsistent pre-culture conditions. Furthermore, a recently developed protocol is described for evaluating the contribution of small molecule treatments towards biofilm resistance to antibacterial substances. Lastly, scanning electron microscopy (SEM) techniques are presented to analyze the three-dimensional spatial arrangement of cells and their surrounding extracellular matrix in a B. subtilis biofilm. SEM facilitates insight into the three-dimensional biofilm architecture and the matrix texture. A combination of the methods described here can greatly assist the study of biofilm development in the presence and absence of biofilm inhibitors, and shed light on the mechanism of action of these inhibitors.

Methodologies for Studying B. subtilis Biofilms as a Model for Characterizing Small Molecule Biofilm Inhibitors

This study presents the development of reproducible methodologies to study biofilm inhibitors and their effects on Bacillus subtilis multicellularity.

הסרת biofilm באמצעות אירוסולים פחמן דו-חמצני ללא חנקן טהר

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Co-מודלים של תרבות Pseudomonas aeruginosa Biofilms גדל על תאים חיים Airway האדם

הכנת מסגרות מתכת אורגנית הידרופובי באמצעות פלזמה משופרת שיקוע הכימי של Perfluoroalkanes להסרת אמוניה

הכנת Aerogels biopolymer בעזרת ממיסים גרין

פלזמה מיקרוגל לא שיווי משקל עבור כימיה יעילה טמפרטורה גבוהה

כרסום Precision של יערות Nanotube הפחמן באמצעות סריקה בלחץ נמוך למיקרוסקופיה אלקטרונית

להשגת לחצים מתונה בכלי אטום באמצעות קרח יבש כמקור₂ CO מוצק

encapsulating ציטוכרום

טכניקות ייצור מיקרו-נוזלים לבדיקות בלחץ גבוה של הובלת קצף CO_{2 סופר-קריטי} בקנה מידה במאגרים לא קונבנציונליים סדוקים

שיבוש אנטי-ארסי של Biofilms פתוגניים באמצעות Lactonases תכנון הנדסי Quorum-מרווה

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