Edinburgh researchers have developed a biosensor that attaches to a smartphone and uses bacteria to detect unsafe arsenic levels – a device that could help millions of people avoid drinking water contaminated by arsenic. Image Dr Baojun Wang testing the new smartphone device on drinking water in Bangladesh According to the team in the School of Biological Sciences, there is an urgent need to provide simple, affordable, on-site solutions for contaminated water sources. In source-limited countries, such as Bangladesh, there is a lack of sufficiently skilled personnel and healthcare facilities to test water for contamination. To tackle this, researchers say new devices could replace existing tests. “Current tests are difficult to use,” says Dr Baojun Wang, the lead researcher and head of the Synthetic Biological Circuit Engineering Lab at Edinburgh. “They need specialist laboratory equipment and can produce toxic chemicals. The sensor device, however, generates easy-to-interpret patterns, similar to volume control bars, which display the level of contamination.” Testing The team tested the arsenic sensors using environment samples from affected wells in Bangladesh, which suffers from some of the world’s highest levels of arsenic-contaminated ground water. “We tested out sensors with samples from wells in a village in Bangladesh,” says Dr Wang. “The arsenic level reported by the sensors was consistent with lab-based standard tests, demonstrating the devices' potential as a simple low-cost-use monitoring tool.” It is estimated around 20 million people in Bangladesh – most in rural poor areas – drink contaminated water. Long-term exposure to unsafe levels of arsenic leads to skin lesions and cancers and is linked to 20 per cent of all deaths in the worst-affected regions. Developing the biosensor using the tests from the wells in Bangladesh, the researchers manipulated the genetic code of the bacteria Escherichia coli (E. coli), and then added genetic components to act as sensor signal amplifiers when arsenic is detected. Water samples were fed into a plastic device containing bacteria suspended in a gel. This produced fluorescent proteins in volume bar-like patterns that were visible and easy-to-interpret in the presence of arsenic. Worldwide health issue Image The device in action in Bangladesh Arsenic is one of the most common elements on Earth and is present as arsenic salts in all water. “The World Health Organization sets the safe level for arsenic in drinking water at 10 parts per billion,” says Dr Wang. “However, many places in the Himalayas and South-East Asia have 10 times that amount of arsenic levels in theirs.” Indeed, the contamination of water by heavy metals is a worldwide health issue, with UNICEF reporting that arsenic-contaminated drinking water is consumed by more than 140 million people worldwide. “We believe that our approach could also be used to detect other environmental toxins,” says Dr Wang. “And our hope is that we will eventually be able to use the technology to diagnose diseases and locate trace environmental hazards such as landmines.” Additional sources WHO Fact sheet: Arsenic (external) UNICEF: Policy brief (pdf) Link to published study (external) The study was funded by the Leverhulme Trust, the London-based biomedical research charity Wellcome, and by the Biotechnology and Biological Sciences Research Council, part of UK Research and Innovation, the largest UK public funder of non-medical bioscience. This article was published on 2023-11-10
