Nanogap dielectrophoresis combined with buffer exchange for detecting protein binding to trapped bioparticles.

Highlights • Electrodes with 20 nm-wide gaps were fabricated by atomic layer lithography. • Nanogap electrodes enable low-voltage dielectrophoresis (DEP) trapping. • Spherical supported lipid bilayers and myelin particles were trapped with DEP. • Integrated microfluidics allow buffer switching and reagent delivery for binding assays. We demonstrate a gold nanogap electrode platform that can rapidly create a linear array of biological particles by low-voltage dielectrophoresis (DEP). We further combine microfluidic buffer exchange to introduce protein molecules in high-conductivity solutions while trapping and immobilizing particles. The nanogap between the gold electrodes enables low operating voltages that prevent unwanted Joule heating in high-conductivity buffers. This platform is used to trap bioparticles composed of lipid membranes such as spherical supported lipid bilayers and brain-derived myelin particles, followed by detection of protein binding to specific membrane-bound receptors. We use bioparticles with different sizes, physicochemical properties, and origins to demonstrate a platform that can be used to study a variety of biomolecular interactions. The low-power linear DEP trap combined with microfluidic buffer exchange has potential to enable a portable biosensing platform to rapidly concentrate rare biological particles and perform on-chip binding assays with improved detection limits in physiological buffers. [ABSTRACT FROM AUTHOR]