A paper-supported aptasensor based on upconversion luminescence resonance energy transfer for the accessible determination of exosomes

Exosomes, as potential cancer diagnostic markers have received close attention in recent years. However, there is still a lack of simple and convenient methods to detect and quantitate exosomes. Herein, we used a simple paper supported aptasensor based on luminescence resonance energy transfer (LRET) from upconversion nanoparticles (UCNPs) to gold nanorods (Au NRs) for the accessible determination of exosomes. When exosomes are present, the two sections of the aptamer can combine with the CD63 protein on the surface of exosomes and form a conjugation to close the distance between UCNPs and Au NRs, which initiates the LRET and promotes luminescence quenching. These variations can be monitored by the homemade image system, and the green channel intensities of obtained colored images were extracted with photoshop software to quantify the luminescence. As a result, the quenching of the luminescence of the UCNPs is linearly correlated to the concentration of the exosomes (in the range of 1.0 x 10(4) similar to 1.0 x 10(8) particles/mu L), enabling the detection and quantification of the exosomes. Such approach can reach a low detection limit of exosomes (1.1 x 10(3) particles/mu L) and effectively reduce the background signal by using UCNPs as a luminescent material. This study provides an efficient and practical approach to the detection of exosomes, which should lead to point-of-care testing in clinical applications.