Tag Archives: bacteria

Cyborg bacteria to reduce carbon dioxide

This video is a bit technical but then it is about work being presented to chemists at the American Chemical Society’s (ACS) at the 254th National Meeting & Exposition Aug. 20 -24, 2017,

For a more plain language explanation, there’s an August 22, 2017 ACS news release (also on EurekAlert),

Photosynthesis provides energy for the vast majority of life on Earth. But chlorophyll, the green pigment that plants use to harvest sunlight, is relatively inefficient. To enable humans to capture more of the sun’s energy than natural photosynthesis can, scientists have taught bacteria to cover themselves in tiny, highly efficient solar panels to produce useful compounds.

“Rather than rely on inefficient chlorophyll to harvest sunlight, I’ve taught bacteria how to grow and cover their bodies with tiny semiconductor nanocrystals,” says Kelsey K. Sakimoto, Ph.D., who carried out the research in the lab of Peidong Yang, Ph.D. “These nanocrystals are much more efficient than chlorophyll and can be grown at a fraction of the cost of manufactured solar panels.”

Humans increasingly are looking to find alternatives to fossil fuels as sources of energy and feedstocks for chemical production. Many scientists have worked to create artificial photosynthetic systems to generate renewable energy and simple organic chemicals using sunlight. Progress has been made, but the systems are not efficient enough for commercial production of fuels and feedstocks.

Research in Yang’s lab at the University of California, Berkeley, where Sakimoto earned his Ph.D., focuses on harnessing inorganic semiconductors that can capture sunlight to organisms such as bacteria that can then use the energy to produce useful chemicals from carbon dioxide and water. “The thrust of research in my lab is to essentially ‘supercharge’ nonphotosynthetic bacteria by providing them energy in the form of electrons from inorganic semiconductors, like cadmium sulfide, that are efficient light absorbers,” Yang says. “We are now looking for more benign light absorbers than cadmium sulfide to provide bacteria with energy from light.”

Sakimoto worked with a naturally occurring, nonphotosynthetic bacterium, Moorella thermoacetica, which, as part of its normal respiration, produces acetic acid from carbon dioxide (CO2). Acetic acid is a versatile chemical that can be readily upgraded to a number of fuels, polymers, pharmaceuticals and commodity chemicals through complementary, genetically engineered bacteria.

When Sakimoto fed cadmium and the amino acid cysteine, which contains a sulfur atom, to the bacteria, they synthesized cadmium sulfide (CdS) nanoparticles, which function as solar panels on their surfaces. The hybrid organism, M. thermoacetica-CdS, produces acetic acid from CO2, water and light. “Once covered with these tiny solar panels, the bacteria can synthesize food, fuels and plastics, all using solar energy,” Sakimoto says. “These bacteria outperform natural photosynthesis.”

The bacteria operate at an efficiency of more than 80 percent, and the process is self-replicating and self-regenerating, making this a zero-waste technology. “Synthetic biology and the ability to expand the product scope of CO2 reduction will be crucial to poising this technology as a replacement, or one of many replacements, for the petrochemical industry,” Sakimoto says.

So, do the inorganic-biological hybrids have commercial potential? “I sure hope so!” he says. “Many current systems in artificial photosynthesis require solid electrodes, which is a huge cost. Our algal biofuels are much more attractive, as the whole CO2-to-chemical apparatus is self-contained and only requires a big vat out in the sun.” But he points out that the system still requires some tweaking to tune both the semiconductor and the bacteria. He also suggests that it is possible that the hybrid bacteria he created may have some naturally occurring analog. “A future direction, if this phenomenon exists in nature, would be to bioprospect for these organisms and put them to use,” he says.

For more insight into the work, check out Dexter Johnson’s Aug. 22, 2017 posting on his Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website),

“It’s actually a natural, overlooked feature of their biology,” explains Sakimoto in an e-mail interview with IEEE Spectrum. “This bacterium has a detoxification pathway, meaning if it encounters a toxic metal, like cadmium, it will try to precipitate it out, thereby detoxifying it. So when we introduce cadmium ions into the growth medium in which M. thermoacetica is hanging out, it will convert the amino acid cysteine into sulfide, which precipitates out cadmium as cadmium sulfide. The crystals then assemble and stick onto the bacterium through normal electrostatic interactions.”

I’ve just excerpted one bit, there’s more in Dexter’s posting.

Monitoring the life of bacteria in microdroplets

Trying to establish better ways to test the effect of drugs on bacteria has led the Institute of Physical Chemistry of the Polish Academy of Sciences to develop a new monitoring technique. From a Jan.  11, 2017 news item on Nanowerk,

So far, however, there has been no quick or accurate method of assessing the oxygen conditions in individual microdroplets. This key obstacle has been overcome at the Institute of Physical Chemistry of the Polish Academy of Sciences.

Not in rows of large industrial tanks, nor on shelves laden with test tubes and beakers. The future of chemistry and biology is barely visible to the eye: it’s hundreds and thousands of microdroplets, whizzing through thin tubules of microfluidic devices. The race is on to find technologies that will make it possible to carry out controlled chemical and biological experiments in microdroplets. At the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw a method of remote, yet rapid and accurate assessment of oxygen consumption by micro-organisms living in individual microdroplets has been demonstrated for the first time.

“Devices for the cultivation of bacteria in microdroplets have the chance to revolutionize work on the development of new antibiotics and the study of mechanisms responsible for the acquisition of drug resistance by bacteria. In one small microfluidic system it is possible to accommodate several hundred or even several thousand microdroplets – and to carry out a different experiment in each of them, for example with different types of microorganisms and at different concentrations of antibiotic in each drop,” describes Prof. Piotr Garstecki (IPC PAS), then explains: “For such studies to be possible, one has to provide the bacteria with conditions for development for even a few weeks. Thus, knowledge about the flow of oxygen to the droplets and the rate of its consumption by the microorganisms becomes extremely important. In our latest system we demonstrate how to read this key information.”

A Jan. 11, 2017 IPC PAS press release on EurekAlert, which originated the  news item, describes the work in more detail,

The bioreactors of the future are water droplets with culture medium suspended in a carrier liquid with which they are immiscible (usually this is oil). In the channel of the microfluidic device each droplet is longer than it is wide and it almost completely fills its lumen; sizes matched in this manner ensure that the drops do not swop places in the channel and throughout the duration of the experiment they can be identified without any problems. At the same time, there has to be a thin layer of oil maintained continuously between each microdroplet and the wall of the channel. Without this, the bacteria would be in direct contact with the walls of the channel so they would be able to settle on them and move from drop to drop. Unfortunately, when the microdroplet is stationary, with time it pushes out the oil separating it from the walls, laying it open to contamination. For this reason the drops must be kept in constant motion – even for weeks.

Growing bacteria need culture medium, and waste products need to be removed from their environment at an appropriate rate. Information about the bacterial oxygen consumption in individual droplets is therefore crucial to the operation of microbioreactors.

“It is immediately obvious where the problem lies. In each of the hundreds of moving droplets measurements need to be carried out at a frequency corresponding to the frequency of division of the bacteria or more, in practice at least once every 15 minutes. In addition, the measurement cannot cause any interference in the microdroplets,” says PhD student Michal Horka (IPC PAS), a co-author of the publication in the journal Analytical Chemistry.

Help was at hand for the Warsaw researchers from chemists from the Austrian Institute of Analytical Chemistry and Food Chemistry at the Graz University of Technology. They provided polymer nanoparticles with a phosphorescent dye, which after excitation emit light for longer the higher the concentration of oxygen in the surrounding solution (the nanoparticles underwent tests at the IPC PAS on bacteria in order to determine their possible toxicity – none was found).

Research on monitoring oxygen consumption in the droplets commenced with the preparation of an aqueous solution with the bacteria, the culture medium and a suitable quantity of nanoparticles. The mixture was injected into the microfluidic system constructed of tubing with Teflon connectors with correspondingly shaped channels. The first module formed droplets with a volume of approx. 4 microlitres, which were directed to the incubation tube wound on a spool. In the middle of its length there was another module, with detectors for measuring oxygen and absorbance.

“In the incubation part in one phase of the cycle the droplets flowed in one direction, in the second – in another, electronically controlled by means of suitable solenoid valves. All this looks seemingly simple enough, but in practice one of the biggest challenges was to ensure a smooth transition between the detection module and the tubing, so that bacterial contamination did not occur at the connections,” explains PhD student Horka.

During their passage through the detection module the droplets flowed under an optical sensor which measured the so-called optical density, which is the standard parameter used to evaluate the number of cells (the more bacteria in the droplets, the less light passes through them). In turn, the measurement of the duration of the phosphorescence of the nanoparticles, evaluating the concentration of oxygen in the microdroplets, was carried out using the Piccolo2 optical detector, provided by the Austrian group. This detector, which looks like a big pen drive, was connected directly to the USB port on the control computer. Comparing information from both sensors, IPC PAS researchers showed that the microfluidic device they had constructed made it possible to regularly and quickly monitor the metabolic activity of bacteria in the individual microdroplets.

“We carried out our tests both with bacteria floating in water singly – this is how the common Escherichia coli bacteria behave – as well as with those having a tendency to stick together in clumps – as is the case for tuberculosis bacilli or others belonging to the same family including Mycobacterium smegmatis which we studied. Evaluation of the rate of oxygen consumption by both species of microorganisms proved to be not only possible, but also reliable,” stresses PhD student Artur Ruszczak (IPC PAS).

The results of the research, funded by the European ERC Starting Grant (Polish side) and the Maria Sklodowska-Curie grant (Austrian side) are an important step in the process of building fully functional microfluidic devices for conducting biological experiments lasting many weeks. A system for culturing bacteria in microdroplets was developed at the IPC PAS a few years ago, however it was constructed on a polycarbonate plate. The maximum dimensions of the plate did not exceed 10 cm, which greatly limited the number of droplets; in addition, as a result of interaction with the polycarbonate, after four days the channels were contaminated with bacteria. Devices of Teflon modules and tubing would not have these disadvantages, and would be suitable for practical applications.

Here’s a link to and a citation for the paper,

Lifetime of Phosphorescence from Nanoparticles Yields Accurate Measurement of Concentration of Oxygen in Microdroplets, Allowing One To Monitor the Metabolism of Bacteria by Michał Horka, Shiwen Sun, Artur Ruszczak, Piotr Garstecki, and Torsten Mayr. Anal. Chem., 2016, 88 (24), pp 12006–12012 DOI: 10.1021/acs.analchem.6b03758 Publication Date (Web): November 23, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

Testing ‘smart’ antibacterial surfaces and eating haute cuisine in space

Housekeeping in space, eh? This seems to be a French initiative. From a Nov. 15, 2016 news item on Nanowerk,

Leti [Laboratoire d’électronique des technologies de l’information (LETI)], an institute of CEA [French Alternative Energies and Atomic Energy Commission or Commissariat a l’Energie Atomique (CEA)] Tech, and three French partners are collaborating in a “house-cleaning” project aboard the International Space Station that will investigate antibacterial properties of new materials in a zero-gravity environment to see if they can improve and simplify cleaning inside spacecraft.

The Matiss experiment, as part of the Proxima Mission sponsored by France’s CNES space agency [Centre national d’études spatiales (CNES); National Centre for Space Studies (CNES)], is based on four identical plaques that European Space Agency (ESA) astronaut Thomas Pesquet, the 10th French citizen to go into space, will take with him and install when he joins the space station in November for a six-month mission. The plaques will be in the European Columbus laboratory in the space station for at least three months, and Pesquet will bring them back to earth for analysis at the conclusion of his mission.

A November 15, 2016 CEA-LETI press release on Business Wire (you may also download it from here), which originated the news item, describes the proposed experiments in more detail,

Leti, in collaboration with the ENS de Lyon, CNRS, the French company Saint Gobain and CNES, selected five advanced materials that could stop bacteria from settling and growing on “smart” surfaces. A sixth material, made of glass, will be used as control material.

The experiment will test the new smart surfaces in a gravity-free, enclosed environment. These surfaces are called “smart” because of their ability to provide an appropriate response to a given stimulus. For example, they may repel bacteria, prevent them from growing on the surface, or create their own biofilms that protect them from the bacteria.

The materials are a mix of advanced technology – from self-assembly monolayers and green polymers to ceramic polymers and water-repellent hybrid silica. By responding protectively to air-borne bacteria they become easier to clean and more hygienic. The experiment will determine which one is most effective and could lead to antibacterial surfaces on elevator buttons and bars in mass-transit cars, for example.

“Leveraging its unique chemistry platform, Leti has been developing gas, liquid and supercritical-phase-collective processes of surface functionalization for more than 10 years,” said Guillaume Nonglaton, Leti’s project manager for surface chemistry for biology and health-care applications. “Three Leti-developed surfaces will be part of the space-station experiment: a fluorinated thin layer, an organic silica and a biocompatible polymer. They were chosen for their hydrophobicity, or lack of attraction properties, their level of reproducibility and their rapid integration within Pesquet’s six-month mission.”

Now, for Haute Cusine

Pesquet is bringing meals from top French chefs Alain Ducasse and Thierry Marx for delectation. The menu includes beef tongue with truffled foie gras and duck breast confit. Here’s more from a Nov. 17, 2016 article by Thibault Marchand (Agence France Presse) ong phys.org,

“We will have food prepared by a Michelin-starred chef at the station. We have food for the big feasts: for Christmas, New Year’s and birthdays. We’ll have two birthdays, mine and Peggy’s,” said the Frenchman, who is also taking a saxophone up with him.

French space rookie Thomas Pesquet, 38, will lift off from the Baikonur cosmodrome in Kazakhstan with veteran US and Russian colleagues Peggy Whitson and Oleg Novitsky, for a six-month mission to the ISS.

Bon appétit! By the way, this is not the first time astronauts have been treated to haute cuisine (see a Dec. 2, 2006 article on the BBC [British Broadcasting Corporation] website.)

The launch

Mark Garcia’s Nov. 17, 2016 posting on one of the NASA (US National Aeronautics and Space Administration) blogs describes this latest launch into space,

The Soyuz MS-03 launched from the Baikonur Cosmodrome in Kazakhstan to the International Space Station at 3:20 p.m. EST Thursday, Nov. 17 (2:20 a.m. Baikonur time, Nov. 18). At the time of launch, the space station was flying about 250 miles over the south Atlantic east of Argentina. NASA astronaut Peggy Whitson, Oleg Novitskiy of Roscosmos and Thomas Pesquet of ESA (European Space Agency) are now safely in orbit.

Over the next two days, the trio will orbit the Earth for approximately two days before docking to the space station’s Rassvet module, at 5:01 p.m. on Saturday, Nov. 19. NASA TV coverage of the docking will begin at 4:15 p.m. Saturday.

Garcia’s post gives you details about how to access more information about the mission. The European Space Agency also offers more information as does Thomas Pesquet on his website.

Nanoparticles for breaking up plaque and preventing cavities

There may be iron in your tooth care future if a team of researchers at the University of Pennsylvania have their way. From a July 26, 2016 news item on ScienceDaily,

The bacteria that live in dental plaque and contribute to tooth decay often resist traditional antimicrobial treatment, as they can “hide” within a sticky biofilm matrix, a glue-like polymer scaffold.

A new strategy conceived by University of Pennsylvania researchers took a more sophisticated approach. Instead of simply applying an antibiotic to the teeth, they took advantage of the pH-sensitive and enzyme-like properties of iron-containing nanoparticles to catalyze the activity of hydrogen peroxide, a commonly used natural antiseptic. The activated hydrogen peroxide produced free radicals that were able to simultaneously degrade the biofilm matrix and kill the bacteria within, significantly reducing plaque and preventing the tooth decay, or cavities, in an animal model.

“Even using a very low concentration of hydrogen peroxide, the process was incredibly effective at disrupting the biofilm,” said Hyun (Michel) Koo, a professor in the Penn School of Dental Medicine’s Department of Orthodontics and divisions of Pediatric Dentistry and Community and Oral Health and the senior author of the study, which was published in the journal Biomaterials. “Adding nanoparticles increased the efficiency of bacterial killing more than 5,000-fold.”

A July 25, 2016 University of Pennsylvania news release, which originated the news item, describes the genesis of the work and provides more details about the current research (Note: A link has been removed),

The work built off a seminal finding by Gao [Lizeng Gao, a postdoctoral researcher in Koo’s lab] and colleagues, published in 2007 in Nature Nanotechnology, showing that nanoparticles, long believed to be biologically and chemically inert, could in fact possess enzyme-like properties. In that study, Gao showed that an iron oxide nanoparticle behaved similarly to a peroxidase, an enzyme found naturally that catalyzes oxidative reactions, often using hydrogen peroxide.

When Gao joined Koo’s lab in 2013, he proposed using these nanoparticles in an oral setting, as the oxidation of hydrogen peroxide produces free radicals that can kill bacteria.

“When he first presented it to me, I was very skeptical,” Koo said, “because these free radicals can also damage healthy tissue. But then he refuted that and told me this is different because the nanoparticles’ activity is dependent on pH.”

Gao had found that the nanoparticles had no catalytic activity at neutral or near-neutral pH of 6.5 or 7, physiological values typically found in blood or in a healthy mouth. But when pH was acidic, closer to 5, they become highly active and can rapidly produce free radicals.

The scenario was ideal for targeting plaque, which can produce an acidic microenvironment when exposed to sugars.

Gao and Koo reached out to Cormode [David Cormode, an assistant professor of radiology and bioengineering], who had experience working with iron oxide nanoparticles in a radiological imaging context, to help them synthesize, characterize and test the effectiveness of the nanoparticles, several forms of which are already FDA-approved for imaging in humans.

Beginning with in vitro studies, which involved growing a biofilm containing the cavity-causing bacteria Streptococcus mutans on a tooth-enamel-like surface and then exposing it to sugar, the researchers confirmed that the nanoparticles adhered to the biofilm, were retained even after treatment stopped and could effectively catalyze hydrogen peroxide in acidic conditions.

They also showed that the nanoparticles’ reaction with a 1 percent or less hydrogen peroxide solution was remarkably effective at killing bacteria, wiping out more than 99.9 percent of the S. mutans in the biofilm within five minutes, an efficacy more than 5,000 times greater than using hydrogen peroxide alone. Even more promising, they demonstrated that the treatment regimen, involving a 30-second topical treatment of the nanoparticles followed by a 30-second treatment with hydrogen peroxide, could break down the biofilm matrix components, essentially removing the protective sticky scaffold.

Moving to an animal model, they applied the nanoparticles and hydrogen peroxide topically to the teeth of rats, which can develop tooth decay when infected with S. mutans just as humans do. Twice-a-day, one-minute treatments for three weeks significantly reduced the onset and severity of carious lesions, the clinical term for tooth decay, compared to the control or treatment with hydrogen peroxide alone. The researchers observed no adverse effects on the gum or oral soft tissues from the treatment.

“It’s very promising,” said Koo. “The efficacy and toxicity need to be validated in clinical studies, but I think the potential is there.”

Among the attractive features of the platform is the fact that the components are relatively inexpensive.

“If you look at the amount you would need for a dose, you’re looking at something like 5 milligrams,” Cormode said. “It’s a tiny amount of material, and the nanoparticles are fairly easily synthesize, so we’re talking about a cost of cents per dose.”

In addition, the platform uses a concentration of hydrogen peroxide, 1 percent, which is lower than many currently available tooth-whitening systems that use 3 to 10 percent concentrations, minimizing the chance of negative side effects.

Looking ahead, Gao, Koo, Cormode and colleagues hope to continue refining and improving upon the effectiveness of the nanoparticle platform to fight biofilms.

“We’re studying the role of nanoparticle coatings, composition, size and so forth so we can engineer the particles for even better performance,” Cormode said.

The funding agencies provide a note of interest (Note: Links have been removed),

The study was funded by the International Association for Dental Research/GlaxoSmithKline Innovation in Oral Health Award, National Science Foundation and University of Pennsylvania Research Foundation.

Presumably the industry as represented by the GlaxoSmithKline Innovation in Oral Health Award is keeping a close eye on this work.

Here’s a link to and a citation for the paper,

Nanocatalysts promote Streptococcus mutans biofilm matrix degradation and enhance bacterial killing to suppress dental caries in vivo by Lizeng Gao, Yuan Liu, Dongyeop Kim, Yong Li, Geelsu Hwang, Pratap C. Naha, David P. Cormode, & Hyun Koo. Biomaterials Volume 101, September 2016, Pages 272–284 doi:10.1016/j.biomaterials.2016.05.051

This paper is behind a paywall.

Nano and food discussion for beginners

I try to make sure there are a range of posts here for various levels of ‘nanotechnology sophistication’ but over time I’ve given less attention to ‘beginner’ posts, i.e., pieces where nanotechnology basics are explained as best as possible. This is largely due to concerns about repetition; I mean, how many times do you want to read that nano means one billionth?

In that spirit, this June 22, 2016 news item on Nanowerk about food and nanotechnology provides a good entry piece that is not terribly repetitive,

Every mouthful of food we eat is teeming with chemical reactions. Adding ingredients and cooking helps us control these reactions and makes the food taste better and last longer. So what if we could target food at the molecular level, sending in specially designed particles to control reactions even more tightly? Well, this is exactly what scientists are trying to do and it has already produced some impressive results – from food that tastes salty without the health risks of adding salt, to bread that contains healthy fish oil but without any fishy aftertaste.

But while this nanotechnology could significantly enhance our food, it also raises big questions about safety. We only have to look at the strong reaction against genetically modified foods to see how important this issue is. How can we ensure that nanotechnology in food will be different? Will our food be safe? And will people accept these new foods?

Nanotechnology is an emerging technology that creates and uses materials and particles at the scale of a nanometre, one billionth of a metre. To get an understanding of just how small this is, if you imagine a nanoparticle was the size of a football then an animal like a sheep would be as big as our planet.

Working with such small particles allows us to create materials and products with improved properties, from lighter bicycles and more durable beer bottles to cosmetic creams with better absorption and toothpastes that stop bacteria from growing. Being able to change a material’s properties means nanotechnology can help create many innovative food products and applications that change the way we process, preserve and package foods.

For example, nanotechnology can be used for “smart” packaging that can monitor the condition of foods while they are stored and transported. When foods are contaminated or going off, the sensors on the packaging pick up gases produced by bacteria and change colour to alert anyone who wants to eat the food.

A June 22, 2016 essay by Seda Erdem (University of Stirling; UK) on The Conversation, which originated the news item, provides more information in this excerpt,

Silver is already used in healthcare products such as dental equipment for its antibacterial properties. Nano-sizing silver particles improves their ability to kill bacteria because it increases the surface area of silver the bacteria are exposed to. Israeli scientists found that also coating packaging paper with nano-sized silver particles [also known as silver nanoparticles] combats bacteria such as E. coli and extends product shelf life.

Another example of nanotechnology’s use in food manufacturing is nano-encapsulation. This technology has been used to mask the taste and odour of tuna fish oil so that it could be used to enrich bread with heart healthy Omega-3 fatty acids. Fish oil particles are packed into a film coating that prevents the fish oil from reacting with oxygen and releasing its smell. The nanocapsules break open only when they reach the stomach so you can receive the health benefits of eating them without experiencing the odour.

Meanwhile, researchers at Nottingham University are looking into nanoscale salt particles than can increase the saltiness of food without increasing the amount of salt.

As with silver, breaking salt into smaller nanosize increases its surface area. This means its flavour can be spread more efficiently. The researchers claim this can reduce the salt content of standard crisps by 90% while keeping the same flavour.

Despite all the opportunities nanotechnology offers the food industry, most developments remain at the research and development stage. This slow uptake is due to the lack of information about the health and environmental impacts of the technology. For example, there is a concern whether ingested nanomaterials migrate to different parts of the body and accumulate in certain organs, such as liver and kidneys. This may then affect the functionality of these organs in the medium to long term.

Unknown risks

However, our knowledge of the risks associated with the use of nanomaterials is incomplete. These issues need to be better understood and addressed for the public to accept nanotechnology in food. This will also depend on the public’s understanding of the technology and how much they trust the food industry and the regulatory process watching over it.

Research has shown, for example, that consumers are more likely to accept nanotechnology when it is used in food packaging rather than in food processing. But nanotechnology in food production was seen as more acceptable if it increased the food’s health benefits, although consumers weren’t necessarily willing to pay more for this.

In our recent research, we found no strong attitudes towards or resistance to nanotechnology in food packaging in the UK. But there was still concern among a small group of consumers about the safety of foods. This shows how important it will be for food producers and regulators to provide consumers with the best available information about nanotechnology, including any uncertainties about the technology.

There you have it.

Bacteria and an anti-superbug coating from Ireland’s Sligo Institute of Technology

Unlike today’s (April 28, 2016) earlier piece about dealing with bacteria, the focus for this research is on superbugs and not the bacteria which form biofilm on medical implants and such. An April 21, 2016 news item on RTE News makes the announcement about a new means of dealing with superbugs,

A discovery by a team of scientists in Ireland could stem the spread of deadly superbugs predicted to kill millions of people worldwide over the coming decades.

The research has found an agent that can be baked into everyday items like smart-phones and door handles to combat the likes of MRSA and E. coli.

The nanotechnology has a 99.9 % kill rate of potentially lethal and drug-resistant bacteria, they say.

Lead scientist Professor Suresh C. Pillai, of Sligo Institute of Technology’s Nanotechnology Research Group, says the discovery is the culmination of 12 years work.

“This is a game changer,” he said.

“This breakthrough will change the whole fight against superbugs. It can effectively control the spread of bacteria.”

An April 21, 2016 Sligo Institute of Technology press release provides some context for the work and a few details about the coating,

News of the discovery comes just days after UK Chancellor of the Exchequer George Osborne warned that superbugs could become deadlier than cancer and are on course to kill 10 million people globally by 2050.

Speaking at the International Monetary Fund (IMF) in Washington, Mr Osborne warned that the problem would slash global GDP by around €100 trillion if it was not tackled.

Using nanotechnology, the discovery is an effective and practical antimicrobial solution — an agent that kills microorganisms or inhibits their growth — that can be used to protect a range of everyday items.

Items include anything made from glass, metallics and ceramics including computer or tablet screens, smartphones, ATMs, door handles, TVs, handrails, lifts, urinals, toilet seats, fridges, microwaves and ceramic floor or wall tiles.

It will be of particular use in hospitals and medical facilities which are losing the battle against the spread of killer superbugs.

Other common uses would include in swimming pools and public buildings, on glass in public buses and trains, sneeze guards protecting food in delis and restaurants as well as in clean rooms in the medical sector.

“It’s absolutely wonderful to finally be at this stage. This breakthrough will change the whole fight against superbugs. It can effectvely control the spread of bacteria,” said Prof. Pillai.

He continued: “Every single person has a sea of bacteria on their hands. The mobile phone is the most contaminated personal item that we can have. Bacteria grows on the phone and can live there for up to five months. As it is contaminated with proteins from saliva and from the hand, It’s fertile land for bacteria and has been shown to carry 30 times more bacteria than a toilet seat.”

The research started at Dublin Institute of Technology (DIT)’s CREST and involves scientists now based at IT Sligo, Dublin City University (DCU) and the University of Surrey. Major researchers included Dr Joanna Carroll and Dr Nigel S. Leyland.

It has been funded for the past eight years by John Browne, founder and CEO of Kastus Technologies Ltd, who is bringing the product to a global market. He was also supported by significant investment from Enterprise Ireland.

As there is nothing that will effectively kill antibiotic-resistant superbugs completely from the surface of items, scientists have been searching for a way to prevent the spread.

This has been in the form of building or ‘baking’ antimicrobial surfaces into products during the manufacturing process.

However, until now, all these materials were toxic or needed UV light in order to make them work. This meant they were not practical for indoor use and had limited commercial application.

“The challenge was the preparation of a solution that was activated by indoor light rather than UV light and we have now done that,” said Prof Pillai.

The new water-based solution can be sprayed onto any glass, ceramic or metallic surface during the production process, rendering the surface 99.9 per cent resistant to superbugs like MRSA, E. coli and other fungi. [emphasis mine]

The solution is sprayed on the product — such as a smartphone glass surface — and then ‘baked’ into it, forming a super-hard surface. The coating is transparent, permanent and scratch resistant and actually forms a harder surface than the original glass or ceramic material.

The team first developed the revolutionary material to work on ceramics and has spent the last five years adapting the formula – which is non-toxic and has no harmful bi-products ‑- to make it work on glass and metallic surfaces.

Research is now underway by the group on how to adapt the solution for use in plastics and paint, allowing even wider use of the protective material.

Prof Pillai, Kastus and the team have obtained a US and a UK patent on the unique process with a number of global patent applications pending. It is rare for such an academic scientific discovery to have such commercial viability.

“I was sold on this from the first moment I heard about it. It’s been a long road to here but it was such a compelling story that it was hard to walk away from so I had to see it through to the end,” said John Browne, Kastus CEO.

He continued: “This is a game changer. The uniqueness of antimicrobia surface treatment means that the applications for it in the real world are endless. The multinational glass manufacturers we are in negotiations with to sell the product to have been searching for years to come up with such a solution but have failed.”

If the coating kills 99.9%, doesn’t that mean 0.1% are immune? If that’s the case, won’t they reproduce and eventually establish themselves as a new kind of superbug?

Here’s a link to and a citation for the paper,

Highly Efficient F, Cu doped TiO2 anti-bacterial visible light active photocatalytic coatings to combat hospital-acquired infections by Nigel S. Leyland, Joanna Podporska-Carroll, John Browne, Steven J. Hinder, Brid Quilty, & Suresh C. Pillai. Scientific Reports 6, Article number: 24770 (2016) doi:10.1038/srep24770 Published online: 21 April 2016

This paper is open access.

Nanotechnology-enabled cleansers in Turkish baths

This item about Turkish baths came to me via Chinese news agency Xinhua. In a March 10, 2016 news item on ShanghaiDaily.com,

It is very common to take a bath, yet it is quite a different experience to bathe in Istanbul’s famed hamams, or bath houses.

Bathing in a hamam is similar to that of a sauna, but is more closely related to ancient Greek and ancient Roman bathing practices, and it involves services like washing, aromatherapy oil massage, reflexology, Indian head massage and facial clay mask.

Both tourists and local Turks alike are fans of Turkish baths, said Banu Cagdas, the owner of Cagaloglu.

As customers are flocking and their number growing, hygiene appears to be the most important issue for Turkish baths.

“Visually there is nothing,” said Cagdas. “It looks like every corner is clean and no one can see the germs and viruses with the naked eye.”

Generally, Turkish baths have been using the traditional ways to maintain the state of hygiene, like bleach.

“The sterilization with bleach, especially a long-lasting sterilization, is very difficult to achieve,” Cagdas said, noting that after two hours of the cleaning, micro-organisms and bacteria start to reproduce again due to the warm and humid environment.

Fungal infections are among the most common diseases in Turkish baths. “Then comes all kind of genital diseases,” said Cagdas.

The team is turning to a cleaning agent developed by Turkish engineers from Sabanci University in Istanbul. The product, the result of five-year efforts based on nanotechnology, is called Antimics.

Antimics can stunt the production of germs, viruses, bacteria and fungi.

“We have been applying the solution to Cagaloglu bath once a month and we observe the rate of bacterium has been dropping each time even further,” Menceoglu told Xinhua.

She explained that Antimics enables the bath’s surface to be covered with a tiny antimicrobial coating and “no single microbe, virus or bacterium can hold on to after the application.”

“Every time we do the cleaning we witness that the bacteria level has been dropping drastically,” she said.

In addition, the eco-friendly new product is not harmful to humans, as opposed to the traditional disinfectant detergents that contain chemicals.

It is possible to get more information about the product (Antimic Nanotego Facebook page and on antimic.com) but you do need Turkish language reading skills.

Hybrid bacterial genes and virus shell combined to create ‘nano reactor’ for hydrogen biofuel

Turning water into fuel may seem like an almost biblical project (e.g., Jesus turning water to wine in the New Testament) but scientists at Indiana University are hopeful they are halfway to their goal. From a Jan. 4, 2016 news item on ScienceDaily,

Scientists at Indiana University have created a highly efficient biomaterial that catalyzes the formation of hydrogen — one half of the “holy grail” of splitting H2O to make hydrogen and oxygen for fueling cheap and efficient cars that run on water.

A Jan. 4, 2016 Indiana University (IU) news release (also on EurekAlert*), which originated the news item, explains further (Note: Links have been removed),

A modified enzyme that gains strength from being protected within the protein shell — or “capsid” — of a bacterial virus, this new material is 150 times more efficient than the unaltered form of the enzyme.

“Essentially, we’ve taken a virus’s ability to self-assemble myriad genetic building blocks and incorporated a very fragile and sensitive enzyme with the remarkable property of taking in protons and spitting out hydrogen gas,” said Trevor Douglas, the Earl Blough Professor of Chemistry in the IU Bloomington College of Arts and Sciences’ Department of Chemistry, who led the study. “The end result is a virus-like particle that behaves the same as a highly sophisticated material that catalyzes the production of hydrogen.”

The genetic material used to create the enzyme, hydrogenase, is produced by two genes from the common bacteria Escherichia coli, inserted inside the protective capsid using methods previously developed by these IU scientists. The genes, hyaA and hyaB, are two genes in E. coli that encode key subunits of the hydrogenase enzyme. The capsid comes from the bacterial virus known as bacteriophage P22.

The resulting biomaterial, called “P22-Hyd,” is not only more efficient than the unaltered enzyme but also is produced through a simple fermentation process at room temperature.

The material is potentially far less expensive and more environmentally friendly to produce than other materials currently used to create fuel cells. The costly and rare metal platinum, for example, is commonly used to catalyze hydrogen as fuel in products such as high-end concept cars.

“This material is comparable to platinum, except it’s truly renewable,” Douglas said. “You don’t need to mine it; you can create it at room temperature on a massive scale using fermentation technology; it’s biodegradable. It’s a very green process to make a very high-end sustainable material.”

In addition, P22-Hyd both breaks the chemical bonds of water to create hydrogen and also works in reverse to recombine hydrogen and oxygen to generate power. “The reaction runs both ways — it can be used either as a hydrogen production catalyst or as a fuel cell catalyst,” Douglas said.

The form of hydrogenase is one of three occurring in nature: di-iron (FeFe)-, iron-only (Fe-only)- and nitrogen-iron (NiFe)-hydrogenase. The third form was selected for the new material due to its ability to easily integrate into biomaterials and tolerate exposure to oxygen.

NiFe-hydrogenase also gains significantly greater resistance upon encapsulation to breakdown from chemicals in the environment, and it retains the ability to catalyze at room temperature. Unaltered NiFe-hydrogenase, by contrast, is highly susceptible to destruction from chemicals in the environment and breaks down at temperatures above room temperature — both of which make the unprotected enzyme a poor choice for use in manufacturing and commercial products such as cars.

These sensitivities are “some of the key reasons enzymes haven’t previously lived up to their promise in technology,” Douglas said. Another is their difficulty to produce.

“No one’s ever had a way to create a large enough amount of this hydrogenase despite its incredible potential for biofuel production. But now we’ve got a method to stabilize and produce high quantities of the material — and enormous increases in efficiency,” he said.

The development is highly significant according to Seung-Wuk Lee, professor of bioengineering at the University of California-Berkeley, who was not a part of the study.

“Douglas’ group has been leading protein- or virus-based nanomaterial development for the last two decades. This is a new pioneering work to produce green and clean fuels to tackle the real-world energy problem that we face today and make an immediate impact in our life in the near future,” said Lee, whose work has been cited in a U.S. Congressional report on the use of viruses in manufacturing.

Beyond the new study, Douglas and his colleagues continue to craft P22-Hyd into an ideal ingredient for hydrogen power by investigating ways to activate a catalytic reaction with sunlight, as opposed to introducing elections using laboratory methods.

“Incorporating this material into a solar-powered system is the next step,” Douglas said.

Here’s a link to and a citation for the paper,

Self-assembling biomolecular catalysts for hydrogen production by Paul C. Jordan, Dustin P. Patterson, Kendall N. Saboda, Ethan J. Edwards, Heini M. Miettinen, Gautam Basu, Megan C. Thielges, & Trevor Douglas. Nature Chemistry (2015) doi:10.1038/nchem.2416 Published online 21 December 2015

This paper is behind a paywall.

*(also on EurekAlert) added on Jan. 5, 2016 at 1550 PST.

Touchless displays with 2D nanosheets and sweat

Swiping touchscreens with your finger has become a dominant means of accessing information in many applications but there is at least one problem associated with this action. From an Oct. 2, 2015 news item on phys.org,

While touchscreens are practical, touchless displays would be even more so. That’s because, despite touchscreens having enabled the smartphone’s advance into our lives and being essential for us to be able to use cash dispensers or ticket machines, they do have certain disadvantages. Touchscreens suffer from mechanical wear over time and are a transmission path for bacteria and viruses. To avoid these problems, scientists at Stuttgart’s Max Planck Institute for Solid State Research and LMU Munich have now developed nanostructures that change their electrical and even their optical properties as soon as a finger comes anywhere near them.

Here’s what a touchless screen looks like when tracking,

Touchless colour change: A nanostructure containing alternating layers of phosphatoantimonate nanosheets and oxide ... [more] © Advanced Materials 2015/MPI for Solid State Research

Touchless colour change: A nanostructure containing alternating layers of phosphatoantimonate nanosheets and oxide … [more]
© Advanced Materials 2015/MPI for Solid State Research

An Oct. 1, 2015 Max Planck Institute press release, which originated the news item, gives technical details,

A touchless display may be able to capitalize on a human trait which is of vital importance, although sometimes unwanted: This is the fact that our body sweats – and is constantly emitting water molecules through tiny pores in the skin. Scientists of the Nanochemistry group led by Bettina Lotsch at the Max Planck Institute for Solid State Research in Stuttgart and the LMU Munich have now been able to visualize the transpiration of a finger with a special moisture sensor which reacts as soon as an object – like an index finger – approaches its surface, without touching it. The increasing humidity is converted into an electrical signal or translated into a colour change, thus enabling it to be measured.

Phosphatoantimonic acid is what enables it to do this. This acid is a crystalline solid at room temperature with a structure made up of antimony, phosphorous, oxygen and hydrogen atoms. “It’s long been known to scientists that this material is able to take up water and swells considerably in the process,” explained Pirmin Ganter, doctoral student at the Max Planck Institute for Solid State Research and the Chemistry Department at LMU Munich. This water uptake also changes the properties of the material. For instance, its electrical conductivity increases as the number of stored water molecules rises. This is what enables it to serve as a measure of ambient moisture.

A sandwich nanomaterial structure exposed to moisture also changes its colour

However, the scientists aren’t so interested in developing a new moisture sensor. What they really want is to use it in touchless displays. “Because these sensors react in a very local manner to any increase in moisture, it is quite conceivable that this sort of material with moisture-dependent properties could also be used for touchless displays and monitors,” said Ganter. Touchless screens of this kind would require nothing more than a finger to get near the display to change their electrical or optical properties – and with them the input signal – at a specific point on the display.

Taking phosphatoantimonate nanosheets as their basis, the Stuttgart scientists then developed a photonic nanostructure which reacts to the moisture by changing colour. “If this was built into a monitor, the users would then receive visible feedback to  their finger motion” explained Katalin Szendrei, also a doctoral student in Bettina Lotsch’s group. To this end, the scientists created a multilayer sandwich material with alternating layers of ultrathin phosphatoantimonate nanosheets and silicon dioxide (SiO2) or titanium dioxide nanoparticles (TiO2). Comprising more than ten layers, the stack ultimately reached a height of little more than one millionth of a metre.

For one thing, the colour of the sandwich material can be set via the thickness of the layers. And for another, the colour of the sandwich changes if the scientists increase the relative humidity in the immediate surroundings of the material, for instance by moving a finger towards the screen. “The reason for this lies in the storage of water molecules between the phosphatoantimonate layers, which makes the layers swell considerably,” explained Katalin Szendrei. “A change in the thickness of the layers in this process is accompanied by a change in the colour of the sensor – produced in a similar way to what gives colour to a butterfly wing or in mother-of-pearl.”

The material reacts to the humidity change within a few milliseconds

This is a property that is fundamentally well known and characteristic of so-called photonic crystals. But scientists had never before observed such a large colour change as they now have in the lab in Stuttgart. “The colour of the nanostructure turns from blue to red when a finger gets near, for example. In this way, the colour can be tuned through the whole of the visible spectrum depending on the amount of water vapour taken up,” stressed Bettina Lotsch.

The scientists’ new approach is not only captivating because of the striking colour change. What’s also important is the fact that the material reacts to the change in humidity within a few milliseconds – literally in the blink of an eye. Previously reported materials normally took several seconds or more to respond. That is much too slow for practical applications. And there’s another thing that other materials couldn’t always do: The sandwich structure consisting of phosphatoantimonate nanosheets and oxide nanoparticles is highly stable from a chemical perspective and responds selectively to water vapour.

A layer protecting against chemical influences has to let moisture through

The scientists can imagine their materials being used in much more than just future generations of smartphones, tablets or notebooks. “Ultimately, we could see touchless displays also being deployed in many places where people currently have to touch monitors to navigate,” said Bettina Lotsch. For instance in cash dispensers or ticket machines, or even at the weighing scales in the supermarket’s vegetable aisle. Displays in public placesthat are used by many different people would have distinct hygiene benefits if they were touchless.

But before we see them being used in such places, the scientists have a few more challenges to overcome. It’s important, for example, that the nanostructures can be produced economically. To minimize wear, the structures still need to be coated with a protective layer if they’re going to be used in anything like a display. And that, again, has to meet not one but two different requirements: It must protect the moisture-sensitive layers against chemical and mechanical influences. And it must, of course, let the moisture pass through. But the Stuttgart scientists have an idea for how to achieve that already. An idea they are currently starting to put into practice with an additional cooperation partner on board.

Dexter Johnson’s Oct. 2, 2015 posting on his Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website) provides some additional context for this research (Note: A link has been removed),

In a world where the “swipe” has become a dominant computer interface method along with moving and clicking the mouse, the question becomes what’s next? For researchers at Stuttgart’s Max Planck Institute for Solid State Research and LMU Munich, Germany, the answer continues to be a swipe, but one in which you don’t actually need to touch the screen with your finger. Researchers call these no-contact computer screens touchless positioning interfaces (TPI).

Here’s a link to and a citation for the paper,

Touchless Optical Finger Motion Tracking Based on 2D Nanosheets with Giant Moisture Responsiveness by Katalin Szendrei, Pirmin Ganter, Olalla Sànchez-Sobrado, Roland Eger, Alexander Kuhn, and Bettina V. Lotsch. Advanced Materials DOI: 10.1002/adma.201503463 Article first published online: 22 SEP 2015

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Greening silver nanoparticles with lignin

A July 13, 2015 news item on phys.org highlights a new approach to making silver nanoparticles safer in the environment,

North Carolina State University researchers have developed an effective and environmentally benign method to combat bacteria by engineering nanoscale particles that add the antimicrobial potency of silver to a core of lignin, a ubiquitous substance found in all plant cells. The findings introduce ideas for better, greener and safer nanotechnology and could lead to enhanced efficiency of antimicrobial products used in agriculture and personal care.

A July 13, 2015 North Carolina State University (NCSU) news release (also on EurekAlert), which originated the news item, adds a bit more information,

As the nanoparticles wipe out the targeted bacteria, they become depleted of silver. The remaining particles degrade easily after disposal because of their biocompatible lignin core, limiting the risk to the environment.

“People have been interested in using silver nanoparticles for antimicrobial purposes, but there are lingering concerns about their environmental impact due to the long-term effects of the used metal nanoparticles released in the environment,” said Velev, INVISTA Professor of Chemical and Biomolecular Engineering at NC State and the paper’s corresponding author. “We show here an inexpensive and environmentally responsible method to make effective antimicrobials with biomaterial cores.”

The researchers used the nanoparticles to attack E. coli, a bacterium that causes food poisoning; Pseudomonas aeruginosa, a common disease-causing bacterium; Ralstonia, a genus of bacteria containing numerous soil-borne pathogen species; and Staphylococcus epidermis, a bacterium that can cause harmful biofilms on plastics – like catheters – in the human body. The nanoparticles were effective against all the bacteria.

The method allows researchers the flexibility to change the nanoparticle recipe in order to target specific microbes. Alexander Richter, the paper’s first author and an NC State Ph.D. candidate who won a 2015 Lemelson-MIT prize, says that the particles could be the basis for reduced risk pesticide products with reduced cost and minimized environmental impact.

“We expect this method to have a broad impact,” Richter said. “We may include less of the antimicrobial ingredient without losing effectiveness while at the same time using an inexpensive technique that has a lower environmental burden. We are now working to scale up the process to synthesize the particles under continuous flow conditions.”

I don’t quite understand how the silver nanoparticles/ions are rendered greener. I gather the lignin is harmless but where do the silver nanoparticles/ions go after they’ve been stripped of their lignin cover and have killed the bacteria? I did try reading the paper’s abstract (not much use for someone with my science level),

Silver nanoparticles have antibacterial properties, but their use has been a cause for concern because they persist in the environment. Here, we show that lignin nanoparticles infused with silver ions and coated with a cationic polyelectrolyte layer form a biodegradable and green alternative to silver nanoparticles. The polyelectrolyte layer promotes the adhesion of the particles to bacterial cell membranes and, together with silver ions, can kill a broad spectrum of bacteria, including Escherichia coli, Pseudomonas aeruginosa and quaternary-amine-resistant Ralstonia sp. Ion depletion studies have shown that the bioactivity of these nanoparticles is time-limited because of the desorption of silver ions. High-throughput bioactivity screening did not reveal increased toxicity of the particles when compared to an equivalent mass of metallic silver nanoparticles or silver nitrate solution. Our results demonstrate that the application of green chemistry principles may allow the synthesis of nanoparticles with biodegradable cores that have higher antimicrobial activity and smaller environmental impact than metallic silver nanoparticles.

If you can explain what happens to the silver nanoparticles, please let me know.

Meanwhile, here’s a link to and a citation for the paper,

An environmentally benign antimicrobial nanoparticle based on a silver-infused lignin core by Alexander P. Richter, Joseph S. Brown, Bhuvnesh Bharti, Amy Wang, Sumit Gangwal, Keith Houck, Elaine A. Cohen Hubal, Vesselin N. Paunov, Simeon D. Stoyanov, & Orlin D. Velev. Nature Nanotechnology (2015) doi:10.1038/nnano.2015.141 Published online 13 July 2015

This paper is behind a paywall.