Chemists obtain new material for antibacteri…

Chemists obtain new material for antibacterial food coatings

RUDN University chemists have developed a simple and convenient method for producing derivatives of the natural polymer chitosan. These derivatives are non-toxic and have a pronounced antibacterial activity at the level of modern antibiotics. These substances can be used in the production of antibacterial protective films for food. The article is published in the journal Food Chemistry.

Preservatives are widely used in the food industry. They are necessary to extend the shelf life of products. On the other hand, preservatives reduce food quality. Some of them can cause allergies (benzoic acid) or be toxic (nitrates, nitrites). Synthetic waxy substances used to coat fruits can be carcinogenic (biphenyl is prohibited in the US and EU). This explains the importance of finding new preservatives that are effective and safe.

Chitosan is a natural polymer derived from chitin, the main component of insect and crustacean shells. It has antibacterial properties and is already used in the food industry for packaging and coating products with a protective film. However, its activity is far inferior to antibiotics.

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janeandersonmapractice: Bio Charcoal Tests #5-…

janeandersonmapractice:

Bio Charcoal Tests #5-10

Below are the results of more bio tests. I’m trying to get through all of the restology/davies bio-composites recipes, so I can make a informed choice which one suits the various applications I intend to use them for. So far the best texture has still been the first one, but I want to be thorough, test them all and add to this list of recipes. Again there are so many variable factors such as drying time and heat affecting the tests, so I haven’t been able to repeat the winning combination thus far.  

  1. Test #5 –  For this recipe I used 5g ground charcoal (blitzed in a coffee grinder), 100ml water, 25g gelatine, 10g of glycerol.  This is the least amount of charcoal out of the all of the recipes and the texture has been influenced by the ratio.  The texture is extremely glossy and shiny, not really what I’m looking for in my final outcomes. I really want to celebrate the matt texture of the material.  
  2. Test #6 – A repeat of the test one, however the texture is completely different this time around, which I believe is because of the larger surface area.
  3. Test #7 – 35g charcoal, 100ml of water, 16g gelatine, 10g of glycerol. I’ve increased the amount of charcoal on previous tests. I used a mixed of finer ground and some larger chunks ground with a pestle and mortar. I had the expectation that this would be the most successful sample to date. It took much longer to dry in the print room drying rack, so this had to be left over night. A minor breakthrough; I’ve now become aware that the samples are best dried naturally!! The heated drying racks keep the materials moist for much longer or they dry glossy. 
  4. Test #8 as above with peppermint essential oil, to hide the smell of gelatine. It worked
  5. Test #9 with the addition of ground rosemary. Not successful as essential oil.
  6. Test #10 – Repeat of 7, this time with a double surface area. I’m starting to sprinkle ground charcoal on top of the more moist areas where it hasn’t spread evenly across the baking sheet.

Left these samples 7-10 to dry naturally for 48 hours in a controlled environment. They dried much harder than expected them to and have no flexibility so unfortunately can’t be rolled in the cylindrical forms. Sadly it’s back to the drawing board to find a balance in increasing the charcoal quantity so to maximise the conductivity, but also having a material that is shapeable. This might be achievable with a finer grind still, so that the particles distribute more evenly in the cook. 

janeandersonmapractice: Charcoal Bioplastic – …

janeandersonmapractice:

Charcoal Bioplastic – Test #4

This is test four. This has a greater degree of glycerol than previous recipes. As you can see, it’s very flexible and has almost a shiny almost pvc/latex quality. It’s way too bendy to be formed into cylindrical shapes, but I could see the potential in other uses. 

janeandersonmapractice: Charcoal Bioplastics T…

janeandersonmapractice:

Charcoal Bioplastics Tests

Here’s a few shots from my first few tests. I’ve used a formula/recipe from Clare Davies’ Restology project that she conducted with FabLab, Barcelona. There’s tons that you learn on the job conducting these tests and there can be enormous variables (environment, heat, drying time, texture, flexibility etc) even if you use a similar amount of each material. 

  1. Test #1 –  For this recipe I used 16g ground charcoal (roughly bashed with a rolling pin), 100ml water, 16g gelatine, 16g of glycerol.  After pouring it in to the silicone mould, I left it to dry over the weekend. I came back to a beautiful looking matt texture, that highlighted every detail of the charcoal. It also had a surprising amount of flexibility and is conductive. There’s only one downside to test 1 – it has a slight meaty (porky) smell, even though charcoal it supposed reduce odours. With this in mind, I swapped out the gelatine for agar in subsequent tests. 
  2. Test #2 – 25g charcoal (finer grind with a coffee grinder), 100ml of water, 15g Agar. Once again poured this into moulds and left to dry. This version started to split as it dried, and once it was fully dry it crumbled into lots of flakey pieces (see pic 4).  Quite clear that without the addition of glycerol it didn’t bind as well.
  3. Test #3 – 25g charcoal, 100ml of water, 10g Agar, 15g Agar. This test took quite some time to dry and appeared to have a more flexibility. Once fully dried it also started to crack. As much as I do not wish to use gelatine to make a more natural product, I feel that I might need to proceed with it as it has proved the most successful binding agent.

At the start of these tests, I used charcoal sticks that could be found at any art shop – but at £5 a pack for minute quantity, I knew I would have to look for a way of procuring bulk amounts to create a large scale piece. I contacted the Coates to see if there was the potential to partner with them and use  any waste offcuts from their willow charcoal production, however they produce no waste. So I managed to find bulk bags of activated charcoal that are used as filters in aquatics – which in fact has an even greater conductivity to artists charcoal.

janeandersonmapractice: Seaweed Collecting Sea…

janeandersonmapractice:

Seaweed Collecting

Seaweed is in abundance on the shores on UK coastlines and could present a sustainable source for bioplastics. This week I went seaweed collecting at Black Rock Sands, Porthmadog in Wales. I’ve been using a mix of gelatine or agar (a vegetarian algae) substitute to bind my bioplastic materials but I’m really intrigued by the textures and the possibilities of binding this with the other materials I’m currently using to allow for a greater flexibility – this is a core property of seaweed. Black Rock Sands is a huge beach with really fine sands, not quite black as one would imagine by the name. There was a myriad of fascinating patterns where the sand and the sea meet which I might incorporate using somehow – either as a pattern to a product. There was a large amount of egg wrack (scophyllum nodosum) seaweed in rock pools. This provides shelter for many species on rocky shores. I’m yet to identify all of the seaweed I collected, so more on that later.

janeandersonmapractice:

janeandersonmapractice:

There are so many innovations going on using waste material and leftovers and The Shellworks is a fine example. Four students from the RCA have developed a series of machines that have been turning waste lobster shells into bioplastics. This is a great demonstration of the whole process and has given me a few ideas of what I’d like to develop to document my material tests.

janeandersonmapractice: Bio Material testing A…

janeandersonmapractice:

Bio Material testing April 2019

Over the Easter break, I’ve started testing bio-materials using a few of the open source recipes from Materiom. I known I wanted to work with material I would be naturally discarding from my weekly shopping – mussel shells, eggshells, Nespresso coffee grounds and spirulina. The recipes are surprising easy to follow and can be made using your usual kitchen equipment (scales, cookers, moulds, thermometer, grinder). I managed to order most of the binding ingredients (agar agar, alginate, glycerol, gelatine and dextrin from Amazon. 

The initial experiments have had varying success, and will require much further robust testing and recipe variations. It’s been really interesting to observe the change in properties through the drying process. Some of the materials started off quite pliable, and then dried to a firm plastic-like material after 48 hours. One reflection I wasn’t expecting to encounter is it’s quite a sensory and hands on process – the smells, the feel of the different textures during the creative process, something that you just don’t encounter with man-made materials. 

I am beginning to see the potential of where these materials could be taken in terms of product development and manufacturing. Charcoal bio-material is a material I am keen to start testing next. Partly due to its attractive silky or matt black appearance, charcoal also has air pollution filtration properties that are worth investigating. Clara Davis is a textile designer who has been working with Fablab in Barcelona conducting test with activated charcoal. 

https://clara-davis.com/albums/research/

Hydrogel removes toxins better than current al…

sci:

A 3D
printed hydrogel structure can absorb metal pollutants in water significantly
faster than solid alternatives.

Clean
and fresh water is essential for human life, and water is a necessity to
agricultural and other industries. However, global population growth and
pollution from industrial waste has put a strain in local fresh water
resources.

A hydrogel is made up of polymer chains that are hydrophilic (attracted to water) and are known for being highly absorbent.

Current
clean-up costs can be extremely expensive, leaving poorer and more remote
populations at risk to exposure of metal pollutants such as lead, mercury,
cadmium and copper, which can lead to severe effects on the neurological,
reproductive and immune systems.

Now,
a group of scientists at the University of Texas at Dallas, US, have developed
a 3D printable hydrogel that is capable of 95% metal removal within 30 minutes.

Clean water is also needed for one’s hygiene, including brushing your teeth and bathing.

The hydrogel is made from a cheap, abundant biopolymer chitosan
and diacrylated pluronic, which forms cDAP. The cDAP mixture is then loaded
into the printer as a liquid and allowed to cool to <4⁰C, before rising
again to room temperature to form a gel that can be used to produce various 3D
printed shapes.

The
Dallas team also tested the reusability of their hydrogel and found that it had
a recovery rate of 98% after five cycles of use, proving it to be a potentially
reliable resource to communities with limited fresh water supply.

Life without clean water. Video: charitywater

‘This
novel and cost-effective approach to remove health and environmental hazards
could be useful for fabricating cheap and safe water filtration devices on site
in polluted areas without the need for industrial scale manufacturing tools,’
the paper reads.


This
article was originally published in SCI’s Polymer
International
. DOI: 10.1002/pi.5787

Creating sustainable bioplastics from electr…

Creating sustainable bioplastics from electricity-eating microbes

Electricity harvested from the sun or wind can be used interchangeably with power from coal or petroleum sources. Or sustainably produced electricity can be turned into something physical and useful. Researchers in Arts & Sciences at Washington University in St. Louis have figured out how to feed electricity to microbes to grow truly green, biodegradable plastic, as reported in the Journal of Industrial Microbiology and Biotechnology.

“As our planet grapples with rampant, petroleum-based plastic use and plastic waste, finding sustainable ways to make bioplastics is becoming more and more important. We have to find new solutions,” said Arpita Bose, assistant professor of biology in Arts & Sciences.

Renewable energy currently accounts for about 11% of total U.S. energy consumption and about 17% of electricity generation.

One of the main issues with renewable electricity is energy storage: how to collect power generated during the sunny and windy hours, and hold it for when it is dark and still. Bioplastics are a good use for that “extra” power from intermittent sources, Bose suggests—as an alternative to battery storage, and instead of using that energy to make a different type of fuel.

Read more.

Bioengineers develop 3-D structures from cra…

Bioengineers develop 3-D structures from crab shells to replace damaged tissues

A team of scientists from Sechenov First Moscow State Medical University used 3-D printing to create biocompatible structures on the basis of chitin obtained from crab shells. This method will help develop structures with given shapes for biomedical purposes, including the replacement of damaged soft tissues in the human body. The article was published in Marine Drugs.

Shells and other byproducts account for 50 percent to 70 percent of the weight of all crabs caught in the world. As a rule, they are destroyed, which requires additional investment. Only a minor part is processed. However, the bodies of marine crustaceans contain a lot of chitin. This polysaccharide is widespread in the wild—for example, the exoskeletons of insects are made of it. By removing certain acetyl groups from chitin, researchers can obtain chitosan, a biopolymer with a unique set of biological, physical, and chemical properties. It is biocompatible, i.e. does not cause inflammation or immune response when implanted into the body. It also has antifungal and antimicrobial properties and gradually decomposes in the body without leaving any toxic components. That is why chitosan and its derivatives are promising for medicine. On this basis, new types of biocompatible structures can be created to restore damaged tissues or carriers for targeted delivery of drugs.

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