Engineered cells help keep diabetes in check

Scientists from Shanghai Key Laboratory of Regulatory Biology have optogenetically engineered cells to produce insulin when illuminated by far-red light. They incorporated the engineered cells in a biocompatible hydrogel capsule, which also contained wirelessly powered red LEDs, to create HydrogeLEDs that can be switched on and off by an external electromagnetic field. In a small pilot experiment, Jiawei Shao and colleagues implanted these HydrogeLEDs into the skin of diabetic mice, enabling them to administer insulin doses remotely via a smartphone application (Sci. Transl. Med. 9 eaal229).

The researchers also paired the system with a custom-engineered Bluetooth-enabled blood glucose meter, creating instant feedback between the therapeutic cells and the diagnostic device. They demonstrated that in vivo production of mouse insulin by the engineered cells could be remotely controlled by smartphone programs or by the glucose meter in a semiautomatic, glucose-dependent manner. The HydrogeLEDs helped the diabetic animals rapidly achieve and maintain stable blood glucose levels over a period of several weeks. The authors note that successfully linking digital signals with optogenetically engineered cells represents an important step toward translating cell-based therapies into the clinic.

Wireless power drives tiny devices in GI tract

A US research team has created an ingestible electronic capsule, containing a capsule-sized antenna, that can power a device in the gastrointestinal (GI) tract. Tests in preclinical models demonstrated the safely of the device, bringing wireless devices for imaging and treating the GI tract a step closer to reality. While other medical devices employ near-field coupling to deliver power wirelessly, this technique is unattainable for most gastrointestinal devices, which must be small enough to be swallowed and lie a significant distance from the body surface. Instead, the researchers used mid-field coupling, which operates at higher frequencies and delivers power two to three times more efficiently, to power deeply implanted devices (Scientific Reports 7 46745).

To test whether mid-field coupling could deliver power from outside the body into the GI tract, the team designed mid-field antennas capable of operating efficiently in tissue at 1.2 GHz. They characterized the antennas in vivo in five anesthetized pigs, placing one antenna outside the body and the other in the oesophagus, stomach and colon. They could transmit power levels of 37.5, 123 and 173 µW, respectively, into these sites, sufficient to wirelessly power a range of medical devices. "Electronic devices that can be placed in the gastrointestinal tract for prolonged periods of time have the potential to transform how we evaluate and treat patients," said Carlo Giovanni Traverso from Brigham and Women's Hospital. "This work describes the first example of remote, wireless transfer of power to a system in the stomach in a large preclinical animal model – a critical step toward bringing these devices into the clinic."

Paper device generates bacteria killing plasma

A Rutgers University-led team has invented an inexpensive, effective way to kill bacteria and sanitize surfaces using paper-based plasma generators. The devices consist of paper with thin layers of aluminium and hexagon patterns that serve as electrodes. By applying a high voltage to stacked sheets of the metallized paper, the team was able to generate atmospheric plasma without an applied vacuum. The fibrous and porous nature of the paper allows gas to permeate its bulk volume, fuelling the plasma and cooling the substrate. Characterization of the generated plasma revealed a detectable level of UV-C, modest surface temperature (60 °C after 60 s) and a high level of ozone (PNAS 114 5119).

In experiments, the paper-based devices produced plasma that deactivated more than 99% of Saccharomyces cerevisiae and more than 99.9% of Escherichia coli cells with 30 s of treatment. "Preliminary results showed that our sanitizers can kill spores from bacteria, which are hard to kill using conventional sterilization methods," said study co-author Qiang Chen. The researchers' motivation was to create personal protective equipment that might contain the spread of infectious diseases. They hope that, in the future, paper-based sanitizers could be used to create clothing that sterilizes itself, devices that sanitize laboratory equipment and smart bandages to heal wounds.

Bioelectrical tools detect serious gut conditions

FlexiMap, a spin-out from the Auckland Bioengineering Institute, is developing tools to measure bioelectrical activity in the stomach and intestine. FlexiMap is already commercializing its FPC mapping electrodes, which surgeons can use intra-operatively to record gastrointestinal electrical activity. "We have embedded a copper circuit with contact electrodes at the end onto a flexible polymer patch that can be placed on the surface of a patient's stomach to measure bioelectrical activity," explained FlexiMap's lead engineer and director Peng Du. Each patch contains 32 recording channels that relay signals to a computer. "We can use eight patches on the outside of a patient's stomach at a time so that's 256 channels. This enables the surgeon to see the propagation of bioelectrical activity in the gut by going from one electrode to the next. The surgeon can see how fast the activity moves, how strong the signal is and from this information, they can tell whether there is an abnormality going on."

In particular, the electrode is being used to detect two conditions: gastroparesis, where pacemaker cells in the stomach no longer function and the stomach loses its bioelectrical activity; and chronic unexplained nausea and vomiting. FlexiMap was the first to accurately diagnose this disease with bioelectrical recordings. The FPC electrodes have already undergone human clinical trials in New Zealand and the USA and are now being sold to academic institutions aligned to hospitals in the USA and China. FlexiMap's ultimate goal is to develop a non-invasive and routinely applicable package for gastro-intestinal analysis.

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