Nanoparticle-based biosensing using interfacial electrokinetic transduction

Abstract

We present a novel label-free electrokinetic method for detecting biomolecular binding on nanoparticles suspended in the vicinity of a laminar microfluidic interface. The sensor is based on the deflection of the liquid interface in an external AC electric field. Biomolecular binding on particles is shown to increase the interfacial electrical conductivity of the suspending electrolyte, which is sensitively transduced as a change in electrokinetic interfacial deflection. Using this approach, we detect the binding of biotin on streptavidin-functionalized nanoparticles at concentrations as low as 500 aM and perform detection of human IgG at clinically relevant concentrations (1.25-12 mg/mL) without labels. The interface response is only influenced by specific binding on nanoparticle binding sites and decreases when the particle concentration of reactive particles is reduced. Furthermore, we show that control experiments with both nonreactive particles and lack of a specific target analyte do not produce interface deflection. This work provides a promising method for quantifying bead-based binding kinetics for sensitive and specific biosensing in solution without labels.

Enhancing affinity‐based electroanalytical biosensors by integrated AC electrokinetic enrichment—A mini review

“…They created a liquid interface for binding by coflowing two different fluid streams through a microfluidic T-channel and integrated an array of parallel point microelectrodes within the main flow channel. Biotin concentrations could be detected as low as 500 aM by using interfacial electrokinetic transduction [77]. Feldman et al studied ACET enhancement of heterogeneous assays in microfluidics.…”

Dielectrophoretic manipulation of nanomaterials: A review

“…Nanoparticles are bulk materials that are three dimensional at the nanometer scale. In recent years, nanoparticles have been widely implemented for nanoscience applications . Thus, effective and efficient nanoparticle manipulation are significant for advancement in these fields.…”

Biosensors based on DNA-functionalized CdTe quantum dots for the enhanced electrochemical detection of human-IgG

“…Developing a simple, rapid, and highly selective method for the detection of proteins is vital in clinical diagnostics, 1,2 while the need to improve the sensitivity of protein detection is still a barrier for clinical immunoassays. 3 Several label methods for sensitive protein detection have been developed, such as electrochemical, [4][5][6][7] chemiluminescence, 8,9 uorescence, 10,11 radioactive labeling, 12,13 and enzyme-linked immunosorbent assays. 14,15 Compared with conventional detection methods, the label-free and real-time detection of proteins, such as obliqueincidence reectivity difference, 16 surface-enhanced Raman scattering, 17 surface plasmon resonance imaging (SPRI), 18 and ellipsometry, 19 have attracted much attention owing to their more sensitive and more accurate properties.…”