Novel Homogeneous Anion Exchange Membranes for Reproducible and Sensitive Nucleic Acid Detection via Current–Voltage Characteristic Measurement

Abstract

One-pot synthesis of novel hydrogel-based anion exchange membranes (AEMs), with only a single-phase monomer mixture, was used to eliminate surface heterogeneity and generate reproducible electroconvective microvortices in the over-limiting region of the current−voltage characteristic (CVC) curves. Diallyldimethylammonium chloride (DDA) was used as the main component to provide the cation charge groups, and 2hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethyl acrylate (EGDMA) were used as the auxiliary structure monomers. The uniform membrane structure allowed reproducible and sensitive DNA detection and quantification, as probe−target surface complexes can gate the ion flux and produce large voltage shifts in the over-limiting region. Suppressed membrane curvature due to controlled swelling is a crucial part to avoid the reduction of depletion region for maintaining the influence of target gene hybridization. Fourier-transform infrared (FTIR) spectroscopy verified the synthesized membrane structure, with a residual vinyl group that allows easy carboxylation via additional photografting reaction. Consequently, a significantly higher DNA probe functionalization efficiency is obtained on the homogeneous AEMs, evidenced by the increasing nitrogen element content and bonding via X-ray photoelectron spectroscopy (XPS). The DDA content was optimized to provide a sufficient coulomb force between AEM and nucleic acid backbone to promote the specific binding efficiency but without high dimensional swelling which might change the surface geometry and restrict the voltage shifting for sensing in the over-limiting region, and the optimal DDA/ HEMA ratio was found to be 4/10. The synthesized AEM sensor for recombinant 35S promoter sequence identification exhibited a reproducible calibration standard curve with dynamic range between 30 fM and 1 μM and high selectivity with only 0.01 V shift for 1 μM nontarget oligo.

Critical selection of shear sheltering in electroconvective flow from chaotic to steady state

“…These results allow one to quantitatively understand the fluid state and velocity statistics in the ECF and provide optimization guidance for the performance design of electromembrane microfluidic systems, such as desalination (Chuang et al 2020), mixing (Guan, Yang & Wu 2021), preconcentration (Qiu et al 2019), charge injection (Guan & Novosselov 2019) and electrodeposition (Chen et al 2016;Zheng et al 2020). In addition, our scaling analysis is performed on the case with the fixed dimensional Debye length, which is a limitation of the hypothetical scenario.…”

An integrated ion-exchange membrane-based microfluidic device for irreversible dissociation and quantification of miRNA from ribonucleoproteins

“…To normalize with respect to variations in the sensor size and surface roughness, the voltage shift of the AEM sensor is calculated based on the over-limiting voltage at a current equal to twice the limiting current. 40,46 The limiting current (I lim ) is measured at the overlap of the slope of the ohmic and limiting regions, shown in Fig. 2A.…”

Overlimiting Current in Nonuniform Arrays of Microchannels: Recirculating Flow and Anticrystallization

“…However, all of these mechanisms have been studied in a fluid domain plus a perm-selective membrane without considering the possibility of network effects through multiple connected micropores or microchannels in the fluid domain. While Chuang et al and Sensale et al have reported vortices on the surface of the membrane, their system has no nonuniform structure in fluid domain. On the other hand, Yossifon et al presented nanoscale asymmetry in which the narrow and wide nanochannels interact with each other in nanoslots, showing nanochannel network effects, not microchannel network effects.…”