Researchers at the Ernest Orlando Lawrence Berkeley National Laboratory have developed a novel method of mimicking cellular detection structures and biochemistry. Specific chemical receptor molecules are bound to membrane-forming, polydiacetylene backbones. Interaction with the receptor's counterpart ligand causes a structural change in the polyacetylene liposome membrane and induces a color change. Raymond Stevens and his colleagues have designed a sensor based on this technology that can detect the presence of toxic E. coli bacteria. The sensors were designed so that the presence of the toxin produced by a virulent strain of E. coli causes a color change, from blue to red. According to Raymond Stevens, "We have made synthetic surfaces that mimic the unique cellular binding sites for the toxins produced by E. coli 0157:H7 interactions. When these toxins are produced, they hunt around for places to bind. When they find the right receptor site, they attempt to bind. This activity in humans causes disease. In the sensor, it is what triggers the color change."
Most conventional detection technology for pathogens relies on laboratory tests (e.g., immunoassays, cultures, etc.). This is time-, labor-, and energy-intensive work. Materials that produce a color change in the presence of pathogen-associated molecules would allow for instant detection of danger.
Detection of pathogenic bacteria and viruses can be difficult and time consuming or even impossible in some cases. Cells, however, are capable of detecting faint traces of molecules with their sensitive biochemical receptors. Mimicking the receptors and having them induce a macroscopically visible color change would allow instant detection of chemicals associated with pathogens and other chemicals.Edit Summary