Multivalent aptasensor array and silver aggregated amplification for multiplex detection in microfluidic devices.

Herein, we developed a rapid and sensitive aptamers-based sandwich assay in microfluidic devices based on multivalent aptasensor array (MAA) chip and silver aggregated amplification (SAA) strategy for the detection of two biomarkers. Firstly, aptamers-modified silver nanoparticles were dotted in array to form MAA chip. Then PDMS was used to form a microfluidic device. After that, target proteins and two kinds of aptamer-modified silver nanoparticles (Tag-A and Tag-B) were rapidly injected into the microfluidic device. The aptamer on MAA chip recognized target, and the target also bound with Tag-A and Tag-B which could aggregate with each other to amplify fluorescence signal. Based on MAA chip and SAA strategy in microfluidic device, a linear response to PDGF-BB (r = 0.999) was obtained in the concentration range from 16 pg mL to 250 ng mL, and the detection limit was 1.4 pg mL. In addition, a linear response to PDGF-BB (r = 0.992) was obtained in the concentration range from 16 pg mL to 250 ng mL in 10% blood serum with detection limit of 7.8 pg mL. Ultimately, this assay was used to simultaneously detect PDGF-BB and VEGF-165, and the results showed good specificity and sensitivity. This assay can also be expanded to sensitive and high-throughput detection of other protein biomarkers by coupling of various aptamers with nanoparticles.