Tag Archives: Felice Frankel

Food sensor made from of silk microneedles looks like velco

These sensors really do look like velcro,

The Velcro-like food sensor, made from an array of silk microneedles, can pierce through plastic packaging to sample food for signs of spoilage and bacterial contamination. Image: Felice Frankel

A September 9, 2020 news item on Nanowerk announces some research from the Massachusetts Institute (MIT),

MIT engineers have designed a Velcro-like food sensor, made from an array of silk microneedles, that pierces through plastic packaging to sample food for signs of spoilage and bacterial contamination.

The sensor’s microneedles are molded from a solution of edible proteins found in silk cocoons, and are designed to draw fluid into the back of the sensor, which is printed with two types of specialized ink. One of these “bioinks” changes color when in contact with fluid of a certain pH range, indicating that the food has spoiled; the other turns color when it senses contaminating bacteria such as pathogenic E. coli.

A Sept. 9, 2020 MIT news release (also on EurekAlert), which originated the news item, delves further into the research,

The researchers attached the sensor to a fillet of raw fish that they had injected with a solution contaminated with E. coli. After less than a day, they found that the part of the sensor that was printed with bacteria-sensing bioink turned from blue to red — a clear sign that the fish was contaminated. After a few more hours, the pH-sensitive bioink also changed color, signaling that the fish had also spoiled.

The results, published today in the journal Advanced Functional Materials, are a first step toward developing a new colorimetric sensor that can detect signs of food spoilage and contamination.

Such smart food sensors might help head off outbreaks such as the recent salmonella contamination in onions and peaches. They could also prevent consumers from throwing out food that may be past a printed expiration date, but is in fact still consumable.

“There is a lot of food that’s wasted due to lack of proper labeling, and we’re throwing food away without even knowing if it’s spoiled or not,” says Benedetto Marelli, the Paul M. Cook Career Development Assistant Professor in MIT’s Department of Civil and Environmental Engineering. “People also waste a lot of food after outbreaks, because they’re not sure if the food is actually contaminated or not. A technology like this would give confidence to the end user to not waste food.”

Marelli’s co-authors on the paper are Doyoon Kim, Yunteng Cao, Dhanushkodi Mariappan, Michael S. Bono Jr., and A. John Hart.

Silk and printing

The new food sensor is the product of a collaboration between Marelli, whose lab harnesses the properties of silk to develop new technologies, and Hart, whose group develops new manufacturing processes.

Hart recently developed a high-resolution floxography technique, realizing microscopic patterns that can enable low-cost printed electronics and sensors. Meanwhile, Marelli had developed a silk-based microneedle stamp that penetrates and delivers nutrients to plants. In conversation, the researchers wondered whether their technologies could be paired to produce a printed food sensor that monitors food safety.

“Assessing the health of food by just measuring its surface is often not good enough. At some point, Benedetto mentioned his group’s microneedle work with plants, and we realized that we could combine our expertise to make a more effective sensor,” Hart recalls.

The team looked to create a sensor that could pierce through the surface of many types of food. The design they came up with consisted of an array of microneedles made from silk.

“Silk is completely edible, nontoxic, and can be used as a food ingredient, and it’s mechanically robust enough to penetrate through a large spectrum of tissue types, like meat, peaches, and lettuce,” Marelli says.

A deeper detection

To make the new sensor, Kim first made a solution of silk fibroin, a protein extracted from moth cocoons, and poured the solution into a silicone microneedle mold. After drying, he peeled away the resulting array of microneedles, each measuring about 1.6 millimeters long and 600 microns wide — about one-third the diameter of a spaghetti strand.

The team then developed solutions for two kinds of bioink — color-changing printable polymers that can be mixed with other sensing ingredients. In this case, the researchers mixed into one bioink an antibody that is sensitive to a molecule in E. coli. When the antibody comes in contact with that molecule, it changes shape and physically pushes on the surrounding polymer, which in turn changes the way the bioink absorbs light. In this way, the bioink can change color when it senses contaminating bacteria.

The researchers made a bioink containing antibodies sensitive to E. coli, and a second bioink sensitive to pH levels that are associated with spoilage. They printed the bacteria-sensing bioink on the surface of the microneedle array, in the pattern of the letter “E,” next to which they printed the pH-sensitive bioink, as a “C.” Both letters initially appeared blue in color.

Kim then embedded pores within each microneedle to increase the array’s ability to draw up fluid via capillary action. To test the new sensor, he bought several fillets of raw fish from a local grocery store and injected each fillet with a fluid containing either E. coli, Salmonella, or the fluid without any contaminants. He stuck a sensor into each fillet. Then, he waited.

After about 16 hours, the team observed that the “E” turned from blue to red, only in the fillet contaminated with E. coli, indicating that the sensor accurately detected the bacterial antigens. After several more hours, both the “C” and “E” in all samples turned red, indicating that every fillet had spoiled.

The researchers also found their new sensor indicates contamination and spoilage faster than existing sensors that only detect pathogens on the surface of foods.

“There are many cavities and holes in food where pathogens are embedded, and surface sensors cannot detect these,” Kim says. “So we have to plug in a bit deeper to improve the reliability of the detection. Using this piercing technique, we also don’t have to open a package to inspect food quality.”

The team is looking for ways to speed up the microneedles’ absorption of fluid, as well as the bioinks’ sensing of contaminants. Once the design is optimized, they envision the sensor could be used at various stages along the supply chain, from operators in processing plants, who can use the sensors to monitor products before they are shipped out, to consumers who may choose to apply the sensors on certain foods to make sure they are safe to eat.

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

A Microneedle Technology for Sampling and Sensing Bacteria in the Food Supply Chain by Doyoon Kim, Yunteng Cao, Dhanushkodi Mariappan, Michael S. Bono Jr., A. John Hart, Benedetto Marelli. DOI: https://doi.org/10.1002/adfm.202005370 First published: 09 September 2020

This paper is behind a paywall.

Telecommunications through chemistry?

This isn’t intended to replace the use of electronics to transmit information but the work that George Whitesides and colleagues at Harvard University have just published (in Angewandte Chemie) is stunning to me.  From the news item on physorg.com,

We currently transmit information electronically; in the future we will most likely use photons. However, these are not the only alternatives. Information can also be transmitted by means of chemical reactions. George M. Whitesides and his colleagues at Harvard University in Cambridge have now developed a concept that allows transmission of alphanumeric information in the form of light pulses with no electricity: the “infofuse”.

Transmitting information by a chemical reaction? This is how the researchers approached the problem initially,

The strips were covered with patterns of dots made of salts of the elements lithium, rubidium, and cesium. When the strip is ignited, the flame travels forward and reaches the dots one after the other. The heat causes the elements to emit light at characteristic wavelengths. The dots may contain combinations of three different salts, resulting in seven possible combinations. A combination of two dots thus allows for 7×7 = 49 different signals.

The researchers have since tweaked the process to address some of the issues such as flames extinguishing themselves too quickly, etc. because,

“We hope that it will be possible to develop a light, portable, non-electric system of information transmission that can be integrated into modern information technology,” says Whitesides. “For example, it could be used to gather and transmit environmental data or to send messages by emergency services.”

Whitesides has been mentioned on this blog before, notably in regards to an article by Robert Fulford (in Canada’s National Post) about a nanotechnology book he  co-authored with Felice Frankel. Interestingly his recently published article on the ‘infofuse’ was funded by the American Cancer Society and supported the US Dept. of Defense’s DARPA (Defense Advanced Research Projects Agency) . A rather unusual pairing, non?

Bacterial nanobots build a pyramid; solar cell breakthrough in Quebec; global nano regulatory framework conference at Northeastern University; Robert Fulford talks about the poetry of nanotechnology

Just when I was thinking that the Canadian nanotechnology scene was slowing down there’s this: A research team at the École Polytechnique de Montréal (Québec) has announced that they’ve trained bacteria to build structures shaped like pyramids. From the news item on Nanowerk,

Faster than lion tamers… More powerful than snake charmers… Make way for the bacteria trainers! Professor Sylvain Martel and his team at the École Polytechnique de Montréal NanoRobotics Laboratory have achieved a new world first: “training” living bacteria to build a nanopyramid.

These miniature construction workers are magnetotactic bacteria (MTB): they have their own internal compasses, allowing them to be pulled by magnetic fields. MTB possess flagella bundles enabling each individual to generate a thrust force of approximately 4 picoNewtons. Professor Martel’s team has succeeded in directing the motion of a group of such bacteria using computer-controlled magnetic fields. In an experiment conducted by Polytechnique researchers, the bacteria transported several epoxy nanobricks and assembled them into a step-pyramid structure, completing the task in just 15 minutes. The researchers have also managed to pilot a group of bacteria through the bloodstream of a rat using the same control apparatus.

Nanowerk also features a video of the magnetotactic bacteria at work.

Solar cell breakthrough?

More Canadian nano from Québec: a researcher (Professor Benoît Marsan) and his team at the Université du Québec à Montréal (UQAM) have provided solutions to two problems which have been inhibiting the development of the very promising Graetzel solar cell that was developed in the 1990s in Switzerland. From the news item on Nanowerk a description of the problems,

Most of the materials used to make this cell are low-cost, easy to manufacture and flexible, allowing them to be integrated into a wide variety of objects and materials. In theory, the Graetzel solar cell has tremendous possibilities. Unfortunately, despite the excellence of the concept, this type of cell has two major problems that have prevented its large-scale commercialisation:

– The electrolyte is: a) extremely corrosive, resulting in a lack of durability; b) densely coloured, preventing the efficient passage of light; and c) limits the device photovoltage to 0.7 volts.

– The cathode is covered with platinum, a material that is expensive, non-transparent and rare. Despite numerous attempts, until Professor Marsan’s recent contribution, no one had been able to find a satisfactory solution to these problem

Now a description of the solutions,

– For the electrolyte, entirely new molecules have been created in the laboratory whose concentration has been increased through the contribution of Professor Livain Breau, also of the Chemistry Department. The resulting liquid or gel is transparent and non-corrosive and can increase the photovoltage, thus improving the cell’s output and stability.

– For the cathode, the platinum can be replaced by cobalt sulphide, which is far less expensive. It is also more efficient, more stable and easier to produce in the laboratory.

More details about the work and publication of the study are at Nanowerk.

Northeastern University and nano regulatory frameworks

According to a news item on Azonano, Northeastern University’s (Boston, MA) School of Law will be hosting a two-day conference on international regulatory frameworks for nanotechnology.

Leading international experts on the global regulation of nanotechnologies, including scientists, lawyers, ethicists and officials from governments, industry stakeholders, and NGOs will join in a two-day conference May 7-8, 2010 at Northeastern University’s School of Law.

The conference will identify best practices that address the needs of industries, the public and regulators. Speakers include representatives from the U.S. Environmental Protection Agency, the Brazil Ministry of Science and Technology, the Korean government, the International Conference of Chemicals Management and National Science Foundation-funded university-industry collaborations.

I checked out the law school’s conference website and noted a pretty good range of speakers from Asia, Europe, and North and South America. It can’t have been easy pulling such a diverse group together. Unfortunately, I didn’t recognize names other than two Canadian ones: Dr. Mark Saner and Pat Roy Mooney.

Saner who’s from Carleton University (Ottawa, Ontario) co-wrote a paper cited by Peter Julian (Canadian Member of Parliament) as one of the materials he used for reference when drawing up his recently tabled bill on nanotechnology regulation. (You can see Julian’s list here.) Saner, when he worked with the Council of Canadian Academies, was charged with drawing together the expert panel that wrote the council’s paper on nanotechnology. That panel put together a report (Small is Different: A Science Perspective on the Regulatory Challenges of the Nanoscale) that does a thoughtful job of discussing nanotechnology, regulations, the precautionary principle, etc. and which you can find here. (As I recall I don’t agree with everything as written in the report but it is, as I noted, thoughtful.)

As for Pat Roy Mooney, he’s the executive director for the ETC Group which is a very well-known (to many scientists and businesses in the technology sectors) civil society group. There’s an Oct. 2009 interview with Mooney here where he discusses (in English) nanotechnology during a festival in Austria.

Robert Fulford and nanotechnology

Canadian journalist and author, Robert Fulford just penned an essay/article about nanotechnology for the National Post. From the article,

Fresh bulletins regularly bring news of startling developments in this era’s most surprising and perhaps most poetic form of science, nanotechnology, the study of the unthinkably small.

It’s a pleasure to read as a literary piece. Fulford mostly concerns himself with visions of what nanotechnology could accomplish and with a book (No small matter) by Felice Frankel and George Whitesides which I first saw mentioned by Andrew Maynard on his 2020 Science blog here.

Site remediation and nano materials; perspectives on risk assessment; Leonardo’s call for nano and art; a new nano art/science book

The Project on Emerging Nanotechnologies (PEN) is holding an event on site remediation on Feb. 4, 2010 (12:30 pm to 1:30 pm EST). From the news release,

A new review article appearing in Environmental Health Perspectives (EHP) co-authored by Dr. Todd Kuiken, Research Associate for the Project on Emerging Nanotechnologies (PEN), Dr. Barbara Karn, Office of Research and Development, U.S. Environmental Protection Agency and Marti Otto, Office of Superfund Remediation and Technology Innovation, U.S. Environmental Protection Agency focuses on the use of nanomaterials for environmental cleanup. It provides an overview of current practices; research findings; societal issues; potential environment, health, and safety implications; and possible future directions for nanoremediation. The authors conclude that the technology could be an effective and economically viable alternative for some current site cleanup practices, but potential risks remain poorly understood.

PEN’s Contaminated Site Remediation: Are Nanomaterials the Answer? features the EHN article’s authors  Kulken, Karn, and Otto on a panel with David Rejeski, PEN’s executive director moderating. PEN also has a map detailing almost 60 sites (mostly in the US, 2  in Canada, 4 in Europe, and 1 in Taiwan) where nanomaterials are being used for remediation.  More from the news release,

According to Dr. Kuiken, “Despite the potentially high performance and low cost of nanoremediation, more research is needed to understand and prevent any potential adverse environmental impacts, particularly studies on full-scale ecosystem-wide impacts. To date, little research has been done.”

In its 2004 report Nanoscience and nanotechnologies: opportunities and uncertainties, the British Royal Society and Royal Academy of Engineering recommended that the use of free manufactured nanoparticles be prohibited for environmental applications such as remediation until further research on potential risks and benefits had been conducted. The European Commission’s Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) called for further risk research in 2005 while acknowledging environmental remediation technology as one of nanotechnology’s potential benefits.

If you wish to attend in person (i.e. you are in Washington, DC), you are asked to RSVP here (they provide a light lunch starting at 12 pm) or you can watch the webcast (no RSVP necessary and I will put up a link to the webcast closer to the date).

On the topic of risk, Michael Berger has written an in depth piece about a recently published article, Redefining research risk priorities for nanomaterials, in the Journal of Nanoparticle Research. From Berger’s piece,

While research in quantitative risk characterization of nanomaterials is crucially important, and no one advocates abandoning this approach, scientists and policy makers must face the reality that many of these knowledge gaps cannot be expected to be closed for many years to come – and decision making will need to continue under conditions of uncertainty. At the same time, current chemical-based research efforts are mainly directed at establishing toxicological and ecotoxicological and exposure data for nanomaterials, with comparatively little research undertaken on the tools or approaches that may facilitate near-term decisions.

In other words, there’s a big lag between developing new products using nanomaterials and the research needed to determine the health and environmental risks associated both with the production and use of these new materials. The precautionary principle suggests that we not produce or adopt these products until we are certain about risks and how to ameliorate and/or eliminate them. That’s an impossible position as we can never anticipate with any certainty what will happen when something is released to the general public or into the environment at large.  From Berger’s piece,

In their article, [Khara Deanna] Grieger [PhD student at Technical University of Denmark (DTU)], Anders Baun, who heads DTU’s Department of Environmental Engineering, and Richard Owens from the Policy Studies Institute in the UK, argue that there has not yet been a significant amount of attention dedicated to the field of timely and informed decision making for near term decisions. “We see this as the central issue for the responsible emergence of nanotechnologies” says Grieger.

Getting back to site remediation using nanomaterials, since it’s already in use as per the map and the authors state that there hasn’t been enough research into risks, do we pull back and adopt the precautionary principle or do we proceed as intelligently as possible in an area where uncertainty rules? That’s a question I will continue to explore as I get my hands on more information.

On a completely different nano front, the Leonardo magazine has issued a call for papers on nano and art,

2011 is the International Year of Chemistry! To celebrate Leonardo is seeking to publish papers and artworks on the intersections of chemistry,
nanotechnology and art for our on-going special section on nanotechnology and the arts. Since its inception nanotech/science has been intimately connected to chemistry; fullerenes, nanoputians, molecular machines, nano-inorganics and self-assembling molecular systems all spring from the minds and labs of chemists, biochemists and chemical engineers. If you’re a nano-oriented chemist who is serious about art, an artist working on the molecular level, or a chemical educator exploring the mysteries of nano through the arts we are especially seeking submissions from you.

You can send proposals, queries, and/or manuscripts to the Leonardo editorial office: leonardomanuscripts@gmail.com. You can read more about the call for papers here at Leblogducorps or you can go here to the Leonardo online journal.

Meanwhile, Andrew Maynard at 2020 Science is posting about a new book which integrates art work in an attempt to explain nanotechnology without ever mentioning it. From Andrew’s posting,

How do you write a book about something few people have heard off, and less seem interested in?  The answer, it seems, is to write about something else.

Felice Frankel and George Whitesides have clearly taken this lesson to heart. Judged by the cover alone, their new book “No Small Matter:  Science at the Nanoscale” is all about science in the Twilight zone of the nanoscale

– where stuff doesn’t behave in the way intuition says it should.

Drat! I can’t make the indent go away. At any rate, do visit 2020 as Andrew to read more from this posting and at least one other where he has gotten permission to excerpt parts of the book (text and images).