A Versatile Platform for Point-of-Care Detection of Molecular Biomarkers

This article presents a point-of-care testing (PoCT) molecular biomarker detection platform based on microfluidics technology. The core of the platform is composed of a miniaturized microfluidic component designed to perform immunoassays for molecular recognition and a fluorescence biosensor system, where the optical transducer is an hydrogenated amorphous silicon (a-Si:H) p-i-n photodiode, which converts the molecular recognition event into an electrical signal proportional to the quantity of emission from the fluorescence label tagged to the target molecule. The fluorescence biosensor system achieved a limit of detection (LOD) of 0.36 nM when measuring free Alexa430 fluorophore in an open microfluidic channel. The microfluidic device was able to successfully replicate the results of a laboratory benchtop immunoassay. As proof of concept, the platform was used to detect abscisic acid (ABA), a biomarker of grape maturation. The results showed a significantly different output for a green grape (low ABA levels) compared with a maturated grape (high ABA levels).