Disease detection just became so easy that anyone could do it… with glow-in-the-dark paper. Just add a drop of blood onto it and wait 20 minutes for the result to appear. The simplicity of this procedure could potentially make it the primary method of choice in the detection and control of infectious diseases. It is the ideal solution, as it is lightweight, has low material costs, is disposable, and is deliverable to end users. The best part is, the results are almost instantaneous.
Brought to you by researchers from Eindhoven University of Technology (TU/e) in the Netherlands and Keio University in Japan. This glow-in-the-dark paper is, in actuality, a fully integrated paper-based analytical system that relies on ratiometric bioluminescence detection. The paper contains antibody-targeting bioluminescent sensing proteins (and other essential assay components) that detect the presence and the concentration of multiple antibodies from whole blood. Antibodies (also known as immunoglobulins, abbreviated Ig) are gamma globulin proteins that are found in blood or other bodily fluids of vertebrates. They are used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses.
The results from the strip are based on the color of emitted light. “A biochemical reaction causes the underside of paper to emit blue-green light,” says TU/e professor and research leader Maarten Merkx. “The bluer the color, the higher the concentration of antibodies.” A normal digital camera, or even a mobile phone, is sufficient to determine the exact color. They have successfully tested three antibodies with their prototype for HIV, flu, and dengue fever.
The color of the glow is caused by the luminous sensor protein developed at TU/e. When it reacts with the drop of blood, there is an initial reaction that produces blue light via bioluminescence. It is the same enzyme that illuminates fireflies and certain fish. The second reaction converts the blue light into a green light. But, if an antibody binds to the sensor protein, the second reaction is blocked. The concentration of antibodies is represented by the ratio of blue and green light. “So not only do you know whether the antibody is in the blood, but also how much,” says Merkx.
Their work represents an important advance in the field of point-of-care testing (POCT). It is shifting paper‐based analytical device technology from academic research laboratories to the marketplace. The test is expected to be commercially available within a few years. Other light-based approaches that put a result in front of a phone camera are covered in upconversion nanoparticle sensors. This type of device is ideally suited for user‐friendly point‐of‐care testing in low‐resource environments. A research paper called Paper‐Based Antibody Detection Devices Using Bioluminescent BRET‐Switching Sensor Proteins was published that reports on the work producing and testing the prototype.
