A multirange paper-based analytical device for identifying low, moderate, and high P. aeruginosa bacterial loads in sputum samples.

In this article we introduce a multirange analytical device that extends the dynamic range of nanoparticle-based immunoassays thanks to a multisensor design. Multirange devices contain low- and high-range sensors in the same analytical platform. The low-range sensor defines the limit of detection and quantifies low concentrated analytes, whereas the high-range sensor defines the upper limit of the dynamic range. A control sensor is also included for registering non-specific interactions. A device capable of distinguishing low, moderate, and high bacterial loads in sputum samples was developed to prove the concept of this approach. Using Pseudomonas aeruginosa as a model analyte, the multirange configuration extended the dynamic range 3 orders of magnitude while maintaining a limit of detection of 104 cells·mL-1. The control sensor was used to subtract matrix interferences, which decreased the number of false positives arising from non-specific interactions. The resulting analytical platform was able to correctly distinguish samples with an infection caused by the target pathogen from samples infected by another microorganism. It could also differentiate samples spiked with low, moderate, or high bacterial loads. The results shown here pave the way to using these devices for estimating the bacterial load in patients with chronic bronchial infection, which is a requirement to personalize the dosage of inhaled antibiotics.