Bio-based gadgets are set to take over sportswear and healthcare
Biosensors are instruments that detect the presence of specific molecules in just about any medium, even at trace concentrations. This capability relies on biological receptors housed inside them which chemically interact with target compounds on contact. These receptors are usually the products of synthetic biology. Bio-engineered bacterial cells, mammal cells, or even proteins, enzymes, and DNA can all function as ultra-sensitive molecular registers. Scientists can also adjust them to ‘report’ contact with target molecules through colour changes or bioluminescence. Receptors can also notify human observers by translating chemical signals into electrical ones.
Biosensors build on the natural propensity of cellular components to detect and adapt to minute changes in their biochemical environment. This evolved survival mechanism is proving its worth against a myriad of health, sustainability, and supply chain issues. Biosensors can signal food spoilage, environmental toxins, and the presence of disease more quickly than many conventional chemical sensing technologies.
Biosensors for rapid medical diagnosis
Biosensors are nimble devices that track an important trend towards tech miniaturisation. This is none more apparent than in medicine, where biosensors have become an important new diagnostic tool. In this context, biosensors solves several problems with traditional health testing procedures. Testing kits can be expensive to make and generally require painful, invasive sampling procedures. Biological samples are often shipped off for analysis in distant laboratories, which lengthens treatment time. By contrast, biosensors offer simple, on-the-spot diagnostics, often requiring only external bodily fluids like sweat or urine.
One exciting medical biosensor startup is the University of Washington spin-off Monod. They have created various biosensors for recognising the spikes on the Covid virus, a cancer-related receptor, and a substance released by the body after a heart attack. Monod’s diagnostic biosensors use a system of proteins and enzymes that detect and report on molecules associated with different diseases. Their probes consist of two proteins. One protein recognises and binds to target substances. Once this happens, it unravels its structure so that it touches a second protein. When the two proteins make contact, they emit a biofluorescent enzyme called luciferase. In 2021, the startup received seed funding of $6 million to expand its technology, build new biosensors, and build usable prototypes.
Glympse Bio is another major medical biosensor startup. They use bio-engineered peptide molecules, an organic substance made of amino acid chains, for medical diagnosis and disease tracking. Peptide molecules are useful as biosensor receptors because they undergo very specific chemical reactions when they encounter enzymes produced by different diseases. Glympse Bio’s propriety machine learning algorithm translates this chemical activity into information on which diseases triggered it. In 2020, they acquired $46.7 million in Series B financing which they will use to develop new biosensors for fibrotic diseases.
Biosensors in sustainability
Biosensors also have applications in sustainability and environmental management. In the field of cleantech, it offers an accurate detection system for environmental pollutants. As with traditional medical diagnostic tools, lab-based methods for identifying environmental pollutants, such as chromatography, can be expensive, bulky, and time-consuming. Cell-based biosensors are comparatively cheap to produce and easy to administer.
Oxford Molecule Biosensors engineer bacteria to hone in on polluting toxins and to emit light upon contact. Crucially, these devices are portable, enabling on-site snap assessments on air, soil, and water quality, even in remote locations. Using bio-engineered bacteria comes with its own environmental risks, however, as modified cells could potentially exchange genes with wild organisms. To solve this, MIT engineers have developed a tough hydrogel casing that prevents lab-engineered bacteria from contaminating natural populations. Uniquely, this protective barrier still allows the bacteria to interact with the molecules outside it. This innovation is a sign that the market ecosystem for cell-based environmental biosensors is rapidly maturing.
Food waste is another areas where biosensors are finding their niche. Currently, around 17 percent of total global food production per year is wasted, with 13 percent of this occurring in the retail chain. US startup Strella Biotech set out to solve this. It created a amino acid-based biosensor for detecting ethylene, a gas emitted by fruit when they are about to ripen. This advance warning system is critical for food suppliers in calculating the optimal time for shipping stored fruit. So far, Strella’s biosensors have been applied to billions of apples and pears. They are now set to be used on kiwi fruit shipped from Australasia to the US. Strella was founded in 2019 by Katherine Sizov, who at the time was a molecular biology undergraduate at the University of Pennsylvania. Already, her technology has attracted investment from Millennium Technology Value Partners, Mark Cuban, Yamaha Motor Ventures and Google Ventures.
Smart sportwear using biosensors
Lightweight, unobtrusive, and capable of granular biochemical monitoring, biosensors are eminently useful for athletes wanting real-time data on their training performance. While health monitoring devices like the Fitbit have captured a huge consumer market in the last decade, biosensor advances are set to shrink these gadgets to the point where they integrate seamlessly into our garments. Textiles embedded with a combination of manipulated cells and electronics will detect body motion, temperature, and biochemical changes on the skin’s surface in real time.
Researchers are just beginning to integrate biosensors into consumer garments. A breakthrough came in 2018 when researchers deposited genetically modified microbes onto a flexible, wearable material. They fashioned the sensor-loaded textile into a running suit and shoe that shape-shifts in response to human sweat. High body temperatures trigger ventilating flaps to open on the running suit, removing moisture from the body. The inner shape of the running shoe adjust in response to heat for increased wearer comfort. These prototype garments used B. subtilis, a benign bacterium found in some fermented foods.
For syn-biobased wearable sensors to capture continuous, accurate data about the body, they need a reliable power source. In 2020, Korean researchers published an innovative solution in the journal of Biosensors and Bioelectronics. They developed a biofuel cell that comes in the form of a textile capable of generating electricity from human sweat. Other possibilities are wearable energy harvesters that generate electricity from sunlight or even physical movements.
The problem with using microbes as continuous biosensors is their limited life-cycle. To keep them alive for prolonged periods, these organisms need a constant flow of nutrients, stable temperatures, and waste extraction. This is why some researchers are turning to cell-free sensors made from the non-living parts of cells like DNA, RNA, or protein molecules. These molecular components perform important functions in living cells but they are themselves inert. Just like any other inorganic substance, they can be stored for long periods.
Even more impressively, RNA and DNA can be arranged into information-processing ‘genetic circuits’ that function much like digital computers. Otherwise known as ‘molecular computers’, these tiny sensing systems can express much more complex information about the substances they are detecting. For example, while ordinary biosensors signal either the presence or absence of a molecule, genetic circuits can express precisely how concentrated it is.
Advances in cell-free biosensors are coming from the medical sector. In response to the Covid pandemic, the Wyss Institute for Biologically Inspired Engineering developed a facemask containing genetic circuit biosensors in 2021. This wearable immediately detects SARS-CoV-2 in the wearer’s breath. The receptors on these biosensors consist of molecular structures ordinarily found in cells and which are responsible for translating DNA into RNA and proteins. Once isolated, they can be freeze-dried for storage and easily activated for use with water, eliminating the impracticalities associated with living cell-based biosensors. “We have essentially shrunk an entire diagnostic laboratory down into a small, synthetic biology-based sensor that works with any face mask, and combines the high accuracy of PCR tests with the speed and low cost of antigen tests,” said Peter Nguyen, a researcher associated with the project. Their biosensor is competitive with gold standard RT-PCR tests for accuracy.
Prototypes like the Wyss Institute’s masks mark a turning point in the biosensor market. We are seeing a gradual convergence between fitness monitoring devices, smart sportwear, and diagnostic medical biosensors. In future, all three sensing applications will draw on the architecture of living organisms to attain high detection sensitivity, easy wearability, and data accuracy. It is likely that the Wyss Institute’s innovation will eventually filter through to the consumer sportswear market.
The biosensor tech company Abbott is another good example of the budding intersections between medical and consumer wellness biosensors. Their body-patch biosensors allow consumers to monitor the physiological changes resulting from dietary and exercise regimens. These sensors rely on enzyme detectors and build directly on Abbott’s existing range of diabetes monitoring technologies. The cost-effectiveness of biosensors compared to conventional laboratory-testing also bodes well for their commercialisation. Small and cheap to produce, they are well-poised to exploit the current trend for personalised health monitoring.