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Spider silk: the future of antimicrobial materials

German scientists demonstrate a world-first – engineered spider silks that inhibit microbial growth

Spider silk has long been celebrated for its extraordinary mechanical behaviour. The combination of high strength and high toughness makes it unique amongst natural fibres. It’s also known to be biocompatible and biodegradable, which has prompted many studies into its relevance to biomedical devices. But spider silk also has another superpower – despite being entirely composed of proteins, typically a nutrition source for microorganisms, it repels them, and can do so for years. For the health care sector – where surface contamination by pathogenic microbe films can lead to life-threatening infections – properties like these are in high demand. But without a detailed understanding of the specific mechanism that confers this microbe-repellence, spider silk can’t easily be adapted for use in medical applications.

But a new paper may change that. Writing in Materials Today [DOI: 10.1016/j.mattod.2020.06.009], a group of German researchers have developed a series of 2D and 3D materials from specially-engineered recombinant spider silk proteins. Based on the dragline silk of the European garden spider Araneus diadematus, they engineered two protein sequences, eADF3 and eADF4, plus several variants thereof. These were processed to produce smooth and patterned films, as well as hydrogels. For comparison, the same structures were made from three other materials – a silkworm protein (B. mori), a biopolymer (PCL), and gelatin, a common material in tissue engineering applications.

In order to systematically analyse the antimicrobial properties of each of these biomaterials, they were tested against a diverse selection of biofilm-forming microbes, including pathogenic bacteria (S. mutans, S. aureus, E. coli) and fungi (C. albicans, P. pastoris). The researchers first investigated the effect of protein structure, charge and molecular weight on microbial adhesion, using two different techniques – one based on fluorescence, which measured microbial viability, and the other on atomic force microscopy, which directly measured adhesive forces. For tests involving E. coli, S. aureus, and P. pastoris, negligible adhesion was found on three of the smooth, 2D spider silk films (eADF4(C16), eADF4(C32NR4), and eADF3((AQ)12)) – they outperformed the control films in all cases.

Next, the University of Bayreuth team compared smooth and micropatterned versions of the films, to explore the effect of topography. Two bacteria and two fungi were seeded on top of these films, and after drying, each sample was imaged with a scanning electron microscope. Their findings were clear – regardless of the topography, the spider silk films again displayed low attachment compared to the control films. To examine the behaviour of 3D spider silk materials, hydrogels were produced for each protein variant and the controls. Bacteria and fungi were easily detected on the gelatin and B. mori hydrogels. In contrast, even after being incubated with the microbes for 10 days, no growth was seen on the spider silk hydrogels.

One drawback to biomaterials that are inherently non-fouling is that they’re often not bioselective. In other words, they’re so effective that they repel all cells, even human ones. This limits their usefulness in applications such as tissue engineering. To elucidate whether these spider silk proteins might be able to display a bioselective behaviour, the team had one final test. They added a cell-binding motif (RGD), known to enhance cell attachment, to the silk proteins. In both film and hydrogen form, this material had pronounced bacterial and fungal-repellent properties. Importantly, when the hydrogel was incubated within a cell culture for 10 days, they found good viability for the cells accompanied by no microbial contamination.

The authors say, “To the best of our knowledge, this is a completely new finding, which opens the door for novel applications of spider silk materials, e.g., as bioselective coatings in various biomedical applications, and for…regeneration medicine.”

—  

Sushma Kumari, Gregor Lang, Elise DeSimone, Christian Spengler, Vanessa T. Trossmann, Susanne Lücker, Martina Hudel, Karin Jacobs, Norbert Krämer, Thomas Scheibel. “Engineered spider silk-based 2D and 3D materials prevent microbial infestation”, Materials Today (2020), article in press. DOI: 10.1016/j.mattod.2020.06.009

Republished by Plato

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German scientists demonstrate a world-first – engineered spider silks that inhibit microbial growth

Spider silk has long been celebrated for its extraordinary mechanical behaviour. The combination of high strength and high toughness makes it unique amongst natural fibres. It’s also known to be biocompatible and biodegradable, which has prompted many studies into its relevance to biomedical devices. But spider silk also has another superpower – despite being entirely composed of proteins, typically a nutrition source for microorganisms, it repels them, and can do so for years. For the health care sector – where surface contamination by pathogenic microbe films can lead to life-threatening infections – properties like these are in high demand. But without a detailed understanding of the specific mechanism that confers this microbe-repellence, spider silk can’t easily be adapted for use in medical applications.

But a new paper may change that. Writing in Materials Today [DOI: 10.1016/j.mattod.2020.06.009], a group of German researchers have developed a series of 2D and 3D materials from specially-engineered recombinant spider silk proteins. Based on the dragline silk of the European garden spider Araneus diadematus, they engineered two protein sequences, eADF3 and eADF4, plus several variants thereof. These were processed to produce smooth and patterned films, as well as hydrogels. For comparison, the same structures were made from three other materials – a silkworm protein (B. mori), a biopolymer (PCL), and gelatin, a common material in tissue engineering applications.

In order to systematically analyse the antimicrobial properties of each of these biomaterials, they were tested against a diverse selection of biofilm-forming microbes, including pathogenic bacteria (S. mutans, S. aureus, E. coli) and fungi (C. albicans, P. pastoris). The researchers first investigated the effect of protein structure, charge and molecular weight on microbial adhesion, using two different techniques – one based on fluorescence, which measured microbial viability, and the other on atomic force microscopy, which directly measured adhesive forces. For tests involving E. coli, S. aureus, and P. pastoris, negligible adhesion was found on three of the smooth, 2D spider silk films (eADF4(C16), eADF4(C32NR4), and eADF3((AQ)12)) – they outperformed the control films in all cases.

Next, the University of Bayreuth team compared smooth and micropatterned versions of the films, to explore the effect of topography. Two bacteria and two fungi were seeded on top of these films, and after drying, each sample was imaged with a scanning electron microscope. Their findings were clear – regardless of the topography, the spider silk films again displayed low attachment compared to the control films. To examine the behaviour of 3D spider silk materials, hydrogels were produced for each protein variant and the controls. Bacteria and fungi were easily detected on the gelatin and B. mori hydrogels. In contrast, even after being incubated with the microbes for 10 days, no growth was seen on the spider silk hydrogels.

One drawback to biomaterials that are inherently non-fouling is that they’re often not bioselective. In other words, they’re so effective that they repel all cells, even human ones. This limits their usefulness in applications such as tissue engineering. To elucidate whether these spider silk proteins might be able to display a bioselective behaviour, the team had one final test. They added a cell-binding motif (RGD), known to enhance cell attachment, to the silk proteins. In both film and hydrogen form, this material had pronounced bacterial and fungal-repellent properties. Importantly, when the hydrogel was incubated within a cell culture for 10 days, they found good viability for the cells accompanied by no microbial contamination.

The authors say, “To the best of our knowledge, this is a completely new finding, which opens the door for novel applications of spider silk materials, e.g., as bioselective coatings in various biomedical applications, and for…regeneration medicine.”

—  

Sushma Kumari, Gregor Lang, Elise DeSimone, Christian Spengler, Vanessa T. Trossmann, Susanne Lücker, Martina Hudel, Karin Jacobs, Norbert Krämer, Thomas Scheibel. “Engineered spider silk-based 2D and 3D materials prevent microbial infestation”, Materials Today (2020), article in press. DOI: 10.1016/j.mattod.2020.06.009

Source: https://www.materialstoday.com/biomaterials/news/spider-silk-the-future-of-antimicrobial-materials/

Metal

Week in Review: Airbus-Boeing saga; industrial production; Liberty’s Thyssenkrupp bid

Before we head into the weekend, let’s take a look back at the week that was and some of the metals storylines here on MetalMiner, including the Airbus–Boeing subsidy saga, industrial…

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Airbus plane

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Before we head into the weekend, let’s take a look back at the week that was and some of the metals storylines here on MetalMiner, including the AirbusBoeing subsidy saga, industrial production, Liberty Steel’s bid for German firm Thyssenkrupp’s steel division and much more.

The MetalMiner 2021 Annual Outlook consolidates our 12-month view and provides buying organizations with a complete understanding of the fundamental factors driving prices and a detailed forecast that can be used when sourcing metals for 2021 — including expected average prices, support and resistance levels.

Week of Oct. 19-23 (Airbus-Boeing saga, industrial production and more)

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Source: http://feedproxy.google.com/~r/agmetalminer/~3/pnksrPnsZb8/

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Metal

Is the upward price trajectory for US HRC and CRC starting to slow?

US flat rolled steel prices are still trending strong, sources note, although sentiment as to how long current price points can last is mixed.

Republished by Plato

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Information Provided By:

SteelOrbis Elektronik Pazaryeri A.Ş. (“SteelOrbis”)
19 Mayıs Mahallesi, Atatürk Caddesi
Şeref Yazgan İş Merkezi, No: 72, Kat: 7, D: 18
Kozyatağı – 34736
Istanbul, Turkey

Trade Registration Number : 541892
MERSİS Number : 0470048178400014
Customer Relations Officer : Sinem Alpkaya
Tel : +90 216 468 10 50
Fax : +90 216 386 41 08

This Information Form has been drawn up in order to provide information to the customer (“Customer”) who seeks a free trial on an electronic environment for the purpose of benefiting from the services offered by the SteelOrbis website at “www.steelorbis.com” prior to acceptance of the Membership Contract, and it allows the Customer to gain clear information on the terms and conditions of the membership to be established as well as to review the text of the Contract in question.

The following successive steps shall be taken in order to establish a free trial:

– The Customer selects the “Free Trial” option on the home page at https://www.steelorbis.com.
– The Customer provides all information requested in the “Free Trial Application” form displayed on the screen and confirms it.
– SteelOrbis sends an account activation e-mail to the e-mail address of the Customer provided in the application form.
– The Customer clicks on the activation link sent to his/her e-mail address and activates his/her account. The website Membership Contract is presented to the Customer during the account activation process.

Storage of the Membership Contract:

You can either save the Membership Contract on your computer or make print-outs of it for storage. The Membership Contract accepted and confirmed by the Customer is not kept by SteelOrbis. You can always get access to the standard Membership Contract displayed on the website. However, as amendments may be made to the standard Contract, it may include some variations in comparison with the text approved by you. Accordingly, it may not be possible for you to access on the website the text you originally approved.

Data entry errors:

The information you should provide for membership application and the fields you should fill in are indicated during each step of the operation. You are obliged to provide such information. If you leave the required fields blank, the system will issue a warning. Please fill in all necessary fields. Prior to the completion of the operation, all data entered by you in the previous step will be displayed once more. Please make sure that the information provided by you is accurate and complete before finally confirming the operation; any missing or incorrect information should be completed or corrected. Any amendment or correction on the information provided by you after the confirmation may be performed by means of website logins after the establishment of the membership.

Our confidentiality policy:

Please click here to review our confidentiality policy.

Source: https://www.steelorbis.com/steel-prices/steel-prices-market-analyses/flats-and-slab/is-the-upward-price-trajectory-for-us-hrc-and-crc-starting-to-slow-1169848.htm

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Metal

US and Canadian rig counts both increase week-on-week

Republished by Plato

Published

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Information Provided By:

SteelOrbis Elektronik Pazaryeri A.Ş. (“SteelOrbis”)
19 Mayıs Mahallesi, Atatürk Caddesi
Şeref Yazgan İş Merkezi, No: 72, Kat: 7, D: 18
Kozyatağı – 34736
Istanbul, Turkey

Trade Registration Number : 541892
MERSİS Number : 0470048178400014
Customer Relations Officer : Sinem Alpkaya
Tel : +90 216 468 10 50
Fax : +90 216 386 41 08

This Information Form has been drawn up in order to provide information to the customer (“Customer”) who seeks a free trial on an electronic environment for the purpose of benefiting from the services offered by the SteelOrbis website at “www.steelorbis.com” prior to acceptance of the Membership Contract, and it allows the Customer to gain clear information on the terms and conditions of the membership to be established as well as to review the text of the Contract in question.

The following successive steps shall be taken in order to establish a free trial:

– The Customer selects the “Free Trial” option on the home page at https://www.steelorbis.com.
– The Customer provides all information requested in the “Free Trial Application” form displayed on the screen and confirms it.
– SteelOrbis sends an account activation e-mail to the e-mail address of the Customer provided in the application form.
– The Customer clicks on the activation link sent to his/her e-mail address and activates his/her account. The website Membership Contract is presented to the Customer during the account activation process.

Storage of the Membership Contract:

You can either save the Membership Contract on your computer or make print-outs of it for storage. The Membership Contract accepted and confirmed by the Customer is not kept by SteelOrbis. You can always get access to the standard Membership Contract displayed on the website. However, as amendments may be made to the standard Contract, it may include some variations in comparison with the text approved by you. Accordingly, it may not be possible for you to access on the website the text you originally approved.

Data entry errors:

The information you should provide for membership application and the fields you should fill in are indicated during each step of the operation. You are obliged to provide such information. If you leave the required fields blank, the system will issue a warning. Please fill in all necessary fields. Prior to the completion of the operation, all data entered by you in the previous step will be displayed once more. Please make sure that the information provided by you is accurate and complete before finally confirming the operation; any missing or incorrect information should be completed or corrected. Any amendment or correction on the information provided by you after the confirmation may be performed by means of website logins after the establishment of the membership.

Our confidentiality policy:

Please click here to review our confidentiality policy.

Source: https://www.steelorbis.com/steel-news/latest-news/us-and-canadian-rig-counts-both-increase-week_on_week-1169852.htm

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