Electronic nose can sniff out bacteria in drinking water

via Seoul National University

via Seoul National University

New technology could be used to detect drugs at airports, diagnose certain cancers and test food quality, researchers say

Humans can detect more than one trillion different smells, according to a study by researchers at The Rockefeller University. With such power to distinguish smells, the human nose can identify the scent of a beautiful flower, detect whether food is past its best or spot danger before it appears.

So what if we could recreate that power in a device? That’s exactly what researchers at Seoul National University have done – and the result has potential applications in healthcare, wine production and airport security.

A team of researchers led by Dr. Tai Hyun Park, a professor in the School of Chemical and Biological Engineering at Seoul National University in Korea, has developed a bioelectronic nose that mimics the human nose. The device can detect traces of bacteria in water by smelling it, without the need for complex equipment and testing.

According to their study published in Biosensors and Bioelectronics, the technology works by using the smell receptors in the human nose. The sensor is simple to use and it can detect tiny amounts of contamination in water, making it more sensitive than existing detection methods. The authors of the study say this could make the technology even more useful in the field.

Detecting microbes in drinking water

There are two main problems caused by bacteria and other microbes in water: they can make the water toxic and make it smell bad. At high concentrations, bacteria can be toxic in drinking water. But at lower levels – virtually undetectable by current culturing techniques – they can cause an “off flavor,” putting people off from drinking it.

The new sensor can sniff out low levels of bacteria and other microbes by detecting the off flavor they give off.

“Water that smells bad isn’t necessarily toxic,” said Dr. Park. “Imagine you don’t do your laundry; it’s not that toxic but you don’t want to wear it because the smell is bad. With drinking water, if there’s off flavor; even if the water isn’t toxic, you don’t want to drink it. We wanted to develop a way to detect and remove this kind of contamination so people are happy to drink water.”

Traditionally, water was tested for contamination with bacteria by taking a sample and trying to grow the bacteria in the lab. When the bacteria grow, scientists can count the number of colonies and calculate the concentration of bacteria in the water. Another approach is to detect the smells directly; this is usually done using techniques that require large scientific equipment, such as gas chromatography or mass spectroscopy.

“These are good ways to detect smell molecules, but they require a large amount of work before the sample is even ready to test,” said Dr. Park. “And all of these tests need to be done in a laboratory with expensive equipment – they’re just not suitable for the field.”

Dr. Park and the team wanted to develop a more convenient, compact device for testing water that is suitable for using on-site. In addition to contamination of drinking water, bacteria and other microbes can also contaminate rivers and lakes – for example, the algal blooms in Hong Kong. Catching this kind of contamination early means it’s easier to control.

Mimicking the human senses

When Thomas Edison first showed his moving pictures to the public in 1891, journalists flocked to his lab to understand how the camera could replicate the way our eyes work. Audio recorders and touch-sensitive tablets had a similar effect, capturing people’s imaginations when they were first introduced. While video, audio and touch technology is familiar to us today, there is not yet an equivalent device that successfully captures information for smell or taste.

“Our eventual goal is to develop a real human nose-like bioelectronic nose,” said Dr. Park. “In the human nose, there are about 400 different olfactory receptors. If we could develop our technology to include all of these, we would have a device that could smell anything we can, at lower concentrations.

Bacteria that contaminate water give off particular smells that are associated with a handful of smell molecules. Two typical odors – earthy and musty – are caused by two different molecules: geosmin (GSM) and 2-methylisoborneol (MIB). The new nose-like device can detect these smells at very low concentrations of just 10ng per liter of water. It’s also very sensitive and can spot a particular smell in a cloud of others.

Since their concern is the bad smell, Dr. Park and his colleagues naturally thought about how the human nose works and adapted its function as a sensor element. The human nose is more complicated than receptors for two smell molecules, so to make a true smelling device, the researchers will need to scale up their efforts.

A universal code for smells

The technology has many other applications, say the researchers. A smelling device could be very useful for the smell industry: perfume, cosmetics, wine and coffee. Certain diseases, such as lung cancer, can cause patients to give off particular smells; dogs have been known to detect these, and a bioelectronic nose opens the path to diagnosis through smell. There’s also a role for security, for example in drug searches at airports.

Read more: Electronic nose can sniff out bacteria in drinking water



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How does a machine smell? Better than it did – Biosensors

via phys.org

via phys.org

Scientists have come up with a way of creating sensors which could allow machines to smell more accurately than humans

Every odour has its own specific pattern which our noses are able to identify. Using a combination of proteins coupled to transistors, for the first time machines are able to differentiate smells that are mirror images of each other, so called chiral molecules, something that has not been possible before. The human nose can distinguish between some of these molecules and the different forms of the same molecule of carvone, for example, can smell either like spearmint or caraway. Previous machines would not have been able to distinguish between the two.

The development will allow the creation of a new generation of biosensors with an acute ability to sniff out problems. These could have many industrial uses such as telling when food has gone off, and they could even be accurate enough to smell how much pollution is in the atmosphere.

A collaboration of academics from The University of Manchester and the University of Bari in Italy, have created a biosensor that utilises an odorant binding protein. The team’s findings are published today in the journal Nature Communications.

Odorant binding proteins are found in the mucus of the nose, which work olfactory receptors helping us to create our perception of smell. The team have found a method of manufacturing these proteins in quantities that would allow them to be used in biosensors.

They have developed methods to change the way the proteins react so that they can recognise different types of chemicals. Using a type of transistor incorporating these proteins the scientists were able to measure the unique changes in current as the proteins reacted to odours, and record them. This is in effect the machine smelling the odour and then sending the message, which can then be decoded.

The system is incredibly sensitive with a detection limit that approaches that of the human nose.

Read more: How does a machine smell? Better than it did


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The scent of cancer


Researchers of the University of Konstanz the first to detect cancer cells using the olfactory senses

A research unit in an international cooperation project, led by the Konstanz-based neurobiologist and zoologist Professor Dr. Giovanni Galizia, has been the first to demonstrate that fruit flies are able to distinguish cancer cells from healthy cells via their olfactory sense. In an article, published on 6 January in the international scientific journal “Scientific Report” by the Nature Publishing Group, the researchers of the University of Konstanz and the University La Sapienza in Rome, Italy, describe how characteristic patterns in the olfactory receptors of transgenic Drosophilae can be recorded when activated by scent. Not only could a clear distinction be made between healthy cells and cancer cells; moreover, groupings could be identified among the different cancer cells.

“What really is new and spectacular about this result is the combination of objective, specific and quantifiable laboratory results and the extremely high sensitivity of a living being that cannot be matched by electronic noses or gas chromatography”, explains Giovanni Galizia. Natural olfactory systems are better suited to detecting the very small differences in scent between healthy cells and cancer cells. This fact has already been shown in experiments with dogs; however, these results are not objectifiable and are thus not applicable for a systematic medical diagnosis.

The researchers from Konstanz and Rome used the fact that single odourant molecules dock to the receptor neurons of the flies’ antenna and thus activate the neurons. In an imaging technique developed by the researchers, the different odourant molecules of the respective scent samples create different patterns of activated neurons, which fluoresce under the microscope when active, thanks to a genetic modification. In the experiment five different types of breast cancer cell lines were analysed, compared to healthy cells and clearly divergent patterns were generated. “As not only cancer cells can be distinguished from healthy cells, but also subgroups were discernible within the cancer cells, it seems that even different types of breast cancer cells can be differentiated via the antenna of Drosophila”, explains Alja Lüdke, member of the research unit and researcher at the University of Konstanz.

Read more . . .


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VIDEO: UF researchers find that ‘peanut butter’ test can help diagnose Alzheimer’s disease

A dollop of peanut butter and a ruler can be used to confirm a diagnosis of early stage Alzheimer’s diseaseUniversity of Florida Health researchers have found.

Jennifer Stamps, a graduate student in the UF McKnight Brain Institute Center for Smell and Taste, and her colleagues reported the findings of a small pilot study in the Journal of the Neurological Sciences.

Stamps came up with the idea of using peanut butter to test for smell sensitivity while she was working with Dr. Kenneth Heilman, the James E. Rooks distinguished professor of neurology and health psychology in the UF College of Medicine’s department of neurology.

She noticed while shadowing in Heilman’s clinic that patients were not tested for their sense of smell. The ability to smell is associated with the first cranial nerve and is often one of the first things to be affected in cognitive decline. Stamps also had been working in the laboratory of Linda Bartoshuk, the William P. Bushnell presidentially endowed professor in the College of Dentistry’s department of community dentistry and behavioral sciences and director of human research in the Center for Smell and Taste.

“Dr. Heilman said, ‘If you can come up with something quick and inexpensive, we can do it,’” Stamps said.

She thought of peanut butter because, she said, it is a “pure odorant” that is only detected by the olfactory nerve and is easy to access.

In the study, patients who were coming to the clinic for testing also sat down with a clinician, 14 grams of peanut butter — which equals about one tablespoon — and a metric ruler. The patient closed his or her eyes and mouth and blocked one nostril. The clinician opened the peanut butter container and held the ruler next to the open nostril while the patient breathed normally. The clinician then moved the peanut butter up the ruler one centimeter at a time during the patient’s exhale until the person could detect an odor. The distance was recorded and the procedure repeated on the other nostril after a 90-second delay.

The clinicians running the test did not know the patients’ diagnoses, which were not usually confirmed until weeks after the initial clinical testing.

The scientists found that patients in the early stages of Alzheimer’s disease had a dramatic difference in detecting odor between the left and right nostril — the left nostril was impaired and did not detect the smell until it was an average of 10 centimeters closer to the nose than the right nostril had made the detection in patients with Alzheimer’s disease. This was not the case in patients with other kinds of dementia; instead, these patients had either no differences in odor detection between nostrils or the right nostril was worse at detecting odor than the left one.

Of the 24 patients tested who had mild cognitive impairment, which sometimes signals Alzheimer’s disease and sometimes turns out to be something else, about 10 patients showed a left nostril impairment and 14 patients did not. The researchers said more studies must be conducted to fully understand the implications.

“At the moment, we can use this test to confirm diagnosis,” Stamps said. “But we plan to study patients with mild cognitive impairment to see if this test might be used to predict which patients are going to get Alzheimer’s disease.”

Read more . . .


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Toward making people invisible to mosquitoes


If a mosquito can’t sense that dinner is ready, there will be no buzzing, no landing and no bite

In an advance toward providing mosquito-plagued people, pets and livestock with an invisibility cloak against these blood-sucking insects, scientists today described discovery of substances that occur naturally on human skin and block mosquitoes’ ability to smell and target their victims.

The presentation was among almost 7,000 scheduled here this week at the 246thNational Meeting & Exposition of the American Chemical Society, the world’s largest scientific society. Thousands of scientists and others are expected to attend the sessions, being held in the Indiana Convention Center and downtown hotels.

Ulrich Bernier, Ph.D., who gave the talk, cited the pressing need for better ways to combat mosquitoes. Far from being just a nuisance, mosquitoes are more deadly to humans than any other animal. Their bites transmit malaria and other diseases that kill an estimated 1 million people around the world each year. In the United States, mosquitoes spread rare types of encephalitis, an inflammation of the brain. They also transmit heartworms to pet dogs and cats.

“Repellents have been the mainstay for preventing mosquito bites,” said Bernier. “The most widely used repellant, DEET, is quite effective and has been in use for a long time. However, some people don’t like the feel or the smell of DEET. We are exploring a different approach, with substances that impair the mosquito’s sense of smell. If a mosquito can’t sense that dinner is ready, there will be no buzzing, no landing and no bite.”

Female mosquitoes, which suck blood to obtain a protein needed to produce fertile eggs, can smell people from over 100 feet away. The Mosquito and Fly Unit at the U.S. Department of Agriculture’s Agricultural Research Service-Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, Fla., has been doing research on mosquito repellents since the 1940s. In the 1990s, they accumulated information on substances secreted through the human skin or formed by bacteria on the skin that make some people more attractive to mosquitoes than others.

A person’s scent, Bernier explained, comes from hundreds of compounds on the skin, many emitted through sweat and others produced by bacteria. To identify which of these attract mosquitoes, Bernier and colleagues used a special mosquito cage divided by a screen. They sprayed various substances into one side of the cage, and documented the effects in attracting mosquitoes. Some compounds, like lactic acid — a common component of human sweat — were definite mosquito lures, drawing 90 percent of the mosquitoes to the screen. With other compounds, however, many of the mosquitoes didn’t even take flight or seemed confused.

“If you put your hand in a cage of mosquitoes where we have released some of these inhibitors, almost all just sit on the back wall and don’t even recognize that the hand is in there. We call that anosmia or hyposmia, the inability to sense smells or a reduced ability to sense smells,” explained Bernier.

Read more . . .


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