A test that uses Blu-ray technology to detect Salmonella, toxic substances, allergens, and cancer biomarkers could help under-resourced installations access capabilities currently beyond their budgets. The researchers say the method's accuracy and sensitivity are similar to that of conventional techniques such as quantitative polymerase chain reaction (PCR). While it's not an accepted methodology, the process offers a practical strategy to investigate samples before applying more exhaustive analytical techniques. "Samples that are shown to be positive by this methodology will also be positive using the other techniques," said Sergi Morais of Polytechnic University of Valencia (UPV; Valencia, Spain), co-author of a paper describing the technique.1
Samples are deposited in small quantities on Blu-ray discs, the surface of which requires no chemical activation. "The hydrophobic nature of the surface of the Blu-ray disc allows the proteins to be locked in place by passive adsorption in a high-density format (64 points in each 1 mm2 drop)," said co-author Ángel Maquieira. It is possible to imprint 138,000 points, each one 125 μm in diameter, on the surface of each disc. The attenuation of the reflected light caused by the reaction product is detected by the Blu-ray drive and inversely correlated with analyte concentration.
The researchers used this approach to analyze the DNA of both Salmonellatyphimurium and Cronobacter sakazakii, an intestinal parasite; they also used it to determine the concentration of microcystins in water, a toxin that causes gastrointestinal disorders or allergic reactions. The technique detects levels of pesticides and other contaminants below the maximum allowed by governments.
The work highlights Blu-ray's capabilities (high sensitivity, speed-scanning, optical resolution, portability) for point-of-care diagnostics and high-throughput screening, as well as in situ and field use for environmental monitoring and agrofood.
1. T. Arnandis-Chover et al., Biosens. Bioelectron., 51, 15, 109–114 (2014).
