Prototype Digital Lateral Flow Sensor Using Impact Electrochemistry in a Competitive Binding Assay

Abstract

This work demonstrates a lateral flow assay concept on the basis of stochastic-impact electrochemistry. To this end, we first elucidate requirements to employ silver nanoparticles as redox-active labels. Then, we present a prototype that utilizes nanoimpacts from biotinylated silver nanoparticles as readouts to detect free biotin in solution based on competitive binding. The detection is performed in a membrane-based microfluidic system, where free biotin and biotinylated particles compete for streptavidin immobilized on embedded latex beads. Excess nanoparticles are then registered downstream at an array of detection electrodes. In this way, we establish a proof of concept that serves as a blueprint for future “digital” lateral flow sensors.

Impact electrochemistry for biosensing: advances and future directions

“…2c). 84 This detection took place within a membrane-based microfluidic platform, where free biotin and biotinylated AgNPs competed for binding to streptavidin immobilized on embedded latex beads. Consequently, the concentration of free biotin could be determined through the electro-oxidative collision of excessive AgNPs at an array of detection electrodes.…”

Recent Developments in Single-Entity Electrochemistry

“…In the later work, selectivity was achieved among other suspended microbes by use of a three-mediator system where menadione mediator selectively penetrates S. cerevisiae to access internal redox centers, subsequently leading to a distinct upward staircase collision current response. Similarly, single collision electrochemistry has been applied to study effects of iron deficiency on plasticity in single vesicles and has been incorporated into a membrane-based microfluidic system based on competitive binding of biotin to Ag nanoparticles versus streptavidin, demonstrating quantitative stochastic electrochemical readouts on an embedded MEA chip . Further advances in single collision electrochemistry applications across various subject areas are detailed in recent reviews and perspectives. − …”

“…Similarly, single collision electrochemistry has been applied to study effects of iron deficiency on plasticity in single vesicles 87 and has been incorporated into a membrane-based microfluidic system based on competitive binding of biotin to Ag nanoparticles versus streptavidin, demonstrating quantitative stochastic electrochemical readouts on an embedded MEA chip. 88 Further advances in single collision electrochemistry applications across various subject areas are detailed in recent reviews and perspectives. 89−93 Recent experiments have also extended collision electrochemistry methodologies to track photoinduced nanoparticle− nanoparticle interactions and nanoparticle morphology transformations.…”

Hydrodynamics-Controlled Single-Particle Electrocatalysis

“…In typical collision electrochemistry, individual electrocatalytically active particles freely diffuse into the electrochemical interface one by one, where they collide and make electrical contact. − Transient collisions can potentially result in the observations of time-resolved current responses when particles have the capability to catalyze the oxidation or reduction of electrolyte solution species. In the collision operating conditions, individual particles serve as single-particle electrodes during their dynamic interactions with the electrode–electrolyte interface, rather than being loaded on a microscale electrode. , The shrinkage of electrode size to the nanoscale endows such an electrode with spherical diffusion characteristics, significantly improving the mass transport in electrocatalysis. − Furthermore, compared to immobilizing an ensemble of particles on the electrode surface, the collision operating condition shows promise in providing resistance to deactivation to a certain extent. , The distinct characteristics of collision electrochemistry contribute to the enhancement in the electrocatalytic activity of particles by several orders of magnitude .…”