Scientists have developed a fast, paper-based test to diagnose tuberculosis that can be read with a smartphone, a technology that is increasingly available in emerging economies. Diagnosing tuberculosis (TB) early can allow patients to receive the medicine they need and also help prevent the disease from spreading. However, in resource-limited areas, equipment requirements and long wait times for results are obstacles to diagnosis and treatment. But Dr Chien-Fu Chen from the National Taiwan University and colleagues have come up with a more practical diagnostic test that can be read with a smartphone, a release to the Ghana News Agency said. The researchers combined gold nanoparticles with fluorescent single-stranded DNA sequences that bind to the genetic material of Mycobacterium tuberculosis, the bacteria that cause TB. These nanoparticles were then incorporated into a paper-based device. Adding even a minute amount of lab-derived, double-stranded DNA from M tuberculosis changed the colour of the test spots within an hour. It said a smartphone camera was used to analyse the colour change to determine the bacterial concentration. The researchers also tested a tissue sample from an infected patient to further demonstrate that the device could be used in the field. The World Health Organization (WHO) estimates that in 2015, 1.4 million people died from TB, with most of these deaths occurring in low- and middle-income countries, researchers said. It said early diagnosis could help curb these numbers. However, conventional methods such as sputum smear microscopy, chest X-rays and molecular-based tests require equipment, electricity and specialised personnel that are not always available in remote or developing areas. The research was published in the journal ACS Sensors.