Diagnostic devices that use assays to detect the presence of certain biomarkers tend to require electricity, a trained person to operate them, and often a considerable investment to start. Scientists at Pennsylvania State University have developed a new platform that can measure the presence of certain enzymes in a sample using a tiny paper-based, easy to operate device that is cheap and doesn’t require any electricity to operate.
The person performing the test simply drops the sample in the middle spot, waits for one of the other spots to turn green, at which point a timer is started. Once the third spot turns green, the time is noted and multiplied by some given factor to determine the target enzyme’s concentration. Depending on the analyte used, the test takes anywhere from 30 seconds to 15 minutes to run.
From the study abstract in Analytical Chemistry:
Different targets can be selected in the assay by changing a small molecule reagent within the paper-based device, and the sensitivity and dynamic range of the assays can be tuned easily by changing the composition and quantity of a signal amplification reagent or by modifying the configuration of the paper-based microfluidic device. By tuning these parameters, limits-of-detection for assays can be adjusted over an analyte concentration range of low femtomolar to low nanomolar, with dynamic ranges for the assays of at least 1 order of magnitude. Furthermore, the assay strategy is compatible with complex fluids such as serum.
Study in Analytical Chemistry: Point-of-Care Assay Platform for Quantifying Active Enzymes to Femtomolar Levels Using Measurements of Time as the Readout