A shear-enhanced CNT-assembly nanosensor platform for ultra-sensitive and selective protein detection
By Li, Diya; Wang, Ceming; Sun, Gongchen; Senapati, Satyajyoti; Chang, Hsueh-Chia
Published in Biosensors and Bioelectronics
2017
Abstract
Abstract Detection and quantification of low-concentration proteins in heterogeneous media are generally plagued by two distinct obstacles: lack of sensitivity due to high dissociation equilibrium constant {KD} and non-specificity due to an abundance of non-targets with similar KD. Herein, we report a nanoscale protein-sensing platform with a non-equilibrium on-off switch that employs dielectrophoretic and hydrodynamic shear forces to overcome these thermodynamic limitations with irreversible kinetics. The detection sensitivity is achieved with complete association of the antibody-antigen-antibody (Ab-Ag-Ab) complex by precisely and rapidly assembling carbon nanotubes (CNT) across two parallel electrodes via sequential {DC} electrophoresis and {AC} dielectrophoresis (DEP), and with single-CNT electron tunneling conductance. The high selectivity is achieved with a critical hydrodynamic shear rate between the activated dissociation shear rates of target and non-target linkers of the aligned CNTs. We are able to reach detection limits of 100 attomolar (aM) and 10 femtomolar (fM) in pure samples for two {ELISA} assays with low and high dissociation constant: biotin/streptavidin (10 fM) and HER2/HER2 antibody (0.44