A Hybrid Paper and 3D Printed Microfluidic Platform for Electrochemical Detection of Ag-Labeled Magnetic Particles

Abstract

Here we present a hybrid microfluidic device (hyFlow) composed of a disposable paper electrode and a three-dimensional (3D) printed plastic chip for the electrochemical detection of a magnetic bead-silver nanoparticle (MB-AgNP) bioconjugate. Detection of micron-size magnetic conjugates in a paper-only fluidic device is a challenging task. Typically, these devices operate by capillary flow or use paper hollow channels and suffer from flow issues due to entrapment of MB conjugates in cellulose/ nitrocellulose fibers. The hyFlow system was designed to minimize such issues and transport the MB conjugate to the electrochemical detection area without using a syringe pump. Moreover, this device is capable of detecting the MB-AgNP conjugate in both preformed (off-chip) and in-situ formed (on-chip) formats. This portable device can store dried assay reagents in a buffered matrix containing 10% sucrose and 10% D(+)-trehalose and successfully resolvate and mix the reagents in less than 2 min to detect electrochemically. The hyFlow system could detect AgNP labels of preformed MB-AgNP conjugates down to concentrations as low as 12 pM, representing an estimated AgNP coverage of 22 AgNPs per MB.