A fluorescent lateral flow biosensor for the quantitative detection of Vaspin using upconverting nanoparticles.

Vaspin is a protein present in human serum that can cause type-2 diabetes, obesity, and other cardiovascular diseases. We report fluorescent upconverting nanoparticles (UCNPs)-based lateral flow biosensor for ultrasensitive detection of Vaspin. A pair (primary and secondary) of cognate aptamers was used that has duo binding with Vaspin. UCNPs with a diameter of around 100 nm were used as a tag to label a detection probe (secondary aptamer). A primary aptamer (capture probe) was immobilized on the test zone. Sandwich type hybridization reactions among the conjugate probe, target Vaspin, and primary aptamer were performed on the lateral flow biosensor. In the presence of target Vaspin, UCNPs were captured on the test zone of the biosensor and the fluorescent intensity of the captured UCNPs was measured through a colorimetric app under NIR. Fluorescence intensity indicates the quantity of Vaspin present in the sample. A range of Vaspin concentration across 0.1–55 ng ml−1 with a Limit of detection (LOD) 39 pg ml−1 was tested through this UCNPs based LFSA with high sensitivity, reproducibility and repeatability, whereas it's actual range in human blood is from 0.1 to 7 ng ml−1. Therefore, this research provides a well-suited lateral flow strip with an ultrasensitive and low-cost approach for the early diagnosis of type-2 diabetes and this could be applied to any targets with a duo of aptamers generated. Schematic illustration of the configuration and measurement of the UCNPs based lateral flow aptasensor for VASPIN detection. Image 1 • A fluorescence based aptasensor was developed for quantitative detection of Vaspin. • Upconversion nanoparticles were utilized as highly sensitive signal label. • A covalent conjugate of secondary aptamer was developed as signaling probe, and detected in the nM range. • The sensor design is lateral flow based and can be applied for other targets if duo aptamers are available. [ABSTRACT FROM AUTHOR]