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Bendable batteries in your body
Chinese researchers have engineered bendable batteries that can run on body-inspired liquids, such as normal IV saline solution and cell culture medium. In their work, published in the journal Chem, the authors designed alternatives to lithium ion batteries by focusing on the mechanical-stress demands of wearable electronics, such as smartwatches, and the safety requirements of implantable electronics. Safety measures for wearable and implantable batteries have generally involved structural reinforcement to prevent hazardous chemicals from leaking out. Instead, the researchers swapped out those toxic and flammable liquids for cheap and environmentally conscious sodium ion solutions. Among those solutions were two biocompatible ones suitable for implantable devices, given that they pose no harm to the surface or interior of the body. Although electrolyte leakage is still undesirable, its danger is minimised by the use of either normal saline solution or a cell culture medium that contains amino acids, sugars and vitamins in addition to sodium ions, and thus mimics the fluid that surrounds human cells. The researchers designed two types of flexible batteries – a 2D “belt”-shaped battery, for which they adhered thin electrode films to a net of steel strands, and a 1D fiber-shaped battery, for which they embedded nanoparticles of electrode material around a carbon nanotube backbone. With sodium sulfate solution as the electrolyte, both battery types outperformed most of the reported wearable lithium ion batteries in terms of charge-holding capacity (an indicator of how long a battery can function without recharging) and power output for their size. That performance held up when the authors folded and bent the batteries to mimic the impact of wrapping a sensor, watch or similar device around one’s arm. Charge-holding capacity was only marginally reduced for the saline and cell culture-based batteries, most likely because they had slightly lower sodium ion content than the sodium sulfate solution. An undesired side reaction involving their fibre-shaped battery is even pointing the researchers toward possible therapeutic applications. The same carbon nanotubes that make up the skeleton of the 1D battery can also accelerate the conversion of dissolved oxygen into hydroxide ions, a process that harms battery effectiveness if left uncontrolled, but as a stand-alone process, it boasts therapeutic potential for treating cancer and bacterial infections.
Disadvantaged kids at higher risk for heart disease later
Researchers from the Murdoch Childrens Research Institute have found that children from socially and economically disadvantaged families and neighbourhoods appear more likely to have thicker carotid artery walls, which in adults may indicate higher risk for heart attack and stroke in later life. The research, published in the Journal of the American Heart Association, analysed both family and neighbourhood socio-economic position data from 1477 Australian families. Socio-economic measures included income, education and the occupation of parents, as well as the relative socio-economic status of the immediate neighbourhood. Between the ages of 11 and 12 years, the children’s right carotid artery was imaged and maximum carotid intima-media thickness measured. The study found that both family and neighbourhood socio-economic position were associated with carotid artery inner layer thickness, but the family association was stronger; children whose family’s socio-economic position was in the bottom quartile (most disadvantaged) at age 11–12 years were 46% more likely to have thicker carotid measurement, that is, above the 75th percentile; and socio-economic position as early as age 2–3 years was linked to thickness in carotid artery measurements at age 11–12 years. Researchers said that when they considered traditional cardiovascular risk factors, including body weight, blood pressure and exposure to second-hand smoke, their findings did not change. Based on their other research studies, the authors proposed that infection and inflammation may be among the additional underlying factors. Infection, which leads to inflammation, is more common among people who are socio-economically disadvantaged, they noted. The authors wrote that, given the link between socio-economic position in infancy and carotid artery measurements at mid-childhood, it may be that cardiovascular disease risk begins before a baby is born. Because this is an observational study, a cause-and-effect association between socio-economic position and carotid intima-media thickness cannot be proved. It is also not yet known whether thicker carotid arteries in mid-childhood are linked to cardiovascular risk in adulthood. All study participants were Australian, which may limit the application of findings to other populations.
Changing ant behaviour with CRISPR
Two independent teams of United States investigators are reporting that gene-editing technology CRISPR has been used to manipulate ant eggs — leading to germline changes that occur in every cell of the adult animals throughout the entire ant colony. The studies have been published in Cell. Because they live in colonies that function like superorganisms, ants are also a valuable model for studying complex biological systems. But ant colonies have been difficult to grow and study in the laboratory because of the complexity of their life cycles. The teams found a way to work around that, using two different species of ants. The Rockefeller team employed a species called clonal raider ants (Ooceraea biroi), which lacks queens in their colonies. Instead, single unfertilised eggs develop as clones, creating large numbers of ants that are genetically identical through parthenogenesis. The other team, a collaboration between researchers at New York University, Arizona State University, the University of Pennsylvania and Vanderbilt University, used Indian jumping ants (Harpegnathos saltator) because they have a feature that makes it easy to transform workers into queens. The gene that both research teams knocked out with CRISPR is called orco (odorant receptor coreceptor). Ants have 350 genes for odorant receptors, a prohibitively large number to manage individually. But due to the unique biology of how the receptors work, the investigators were able to block the function of all 350 with a single gene knockout. Once the gene was knocked out, the ants were effectively blind to the pheromone signals they normally use to communicate. Without those chemical cues, they become asocial, wandering out of the nest and failing to hunt for food. More surprisingly, knocking out orco also affected the brain anatomy in the adult animals of both species. In the same way that humans have specialised processing centres in the brain for things such as language and facial recognition, ants have centres that are responsible for perceiving and processing olfactory cues that are expanded compared with other insects. But in these ants, the substructures of these sensory centres, called the antennal lobe glomeruli, were largely missing. In a third related study from the University of Pennsylvania, researchers altered ant behaviour using the brain chemical corazonin. When corazonin is injected into ants transitioning to become a pseudo-queen, it suppresses expression of the brain protein vitellogenin. This change stimulated worker-like hunting behaviours, while inhibiting pseudo-queen behaviours, such as duelling and egg deposition.
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