Taiwan scholars invent paper based test for TB
A research team at
National Taiwan University have developed a more practical diagnostic test for tuberculosis (TB) that can be read with a smartphone. The researchers combined gold nanoparticles with singlestranded DNA sequences that bind to the genetic material of Mycobacterium tuberculosis, the bacteria that cause TB. These nanoparticles were then incorporated into a paperbased device. By utilizing surface plasmon resonance effect, the researchers were able to monitor changes in the color of a gold nanoparticle colloid based on the effects of single-stranded DNA probe molecules hybridizing with targeted double-stranded TB DNA. The hybridization event changes the surface charge density of the nanoparticles, causing them to aggregate to various degrees, which modifies the color of the solution in a manner that can be readily measured to determine the concentration of the targeted DNA analyte.
Adding even a small amount of lab-derived, double-stranded DNA from M. tuberculosis changed the color of the test spots within an hour. A smartphone camera was used to analyze the color 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.