Afi-Chip: An Equipment-free, Low-cost and Universal Binding Ligand Affinity Evaluation Platform
Yanling Song, Yuanzhi Shi, Xingrui Li, Yanli Ma, Mingxuan Gao, Dan Liu, Yu Mao, Zhi Zhu, Hui Lin, Chaoyong Yang*
Abstract:
Binding affinity characterization is of great importance for aptamer screening because the dissociation constant (
Kd) value is a key parameter for evaluating molecular interaction. However, conventional methods often require sophisticated equipment and time-consuming processing. Here, we present a portable device, Afi-Chip, as an equipment-free, rapid, low-cost and universal platform for evaluation of the aptamer affinity. The Afi-Chip displays a distance readout based on the reaction of an enzyme catalyzing the decomposition of H
2O
2for gas generation to push the movement of ink bar. Taking advantage of translating recognition signal to distance signal and realizing the regents mixing and quantitative readout on chip, we successfully monitored the aptamer evolution process and characterized binding affinity of aptamers against multiple types of targets, including small molecule glucose, cancer biomarker protein EpCAM, and tumor cell SW620. We also applied the Afi-Chip for rapid characterization of the affinity between anti-HCG and HCG to demonstrate the generality for molecular interaction study. All of the
Kdvalues obtained are comparable to those reported in literature or obtained by sophisticate instruments such as flow cytometer. The Afi-Chip offers a new approach for equipment-free investigation of molecular interactions, such as aptamer identification, ligand selection monitoring, drug screening and inhibitor screening.
