ac402550f_si_001.pdf (112.77 kB)
Exploiting Enzyme Catalysis in Ultra-Low Ion Strength Media for Impedance Biosensing of Avian Influenza Virus Using a Bare Interdigitated Electrode
journal contribution
posted on 2014-02-18, 00:00 authored by Yingchun Fu, Zachary Callaway, Jacob Lum, Ronghui Wang, Jianhan Lin, Yanbin LiEnzyme
catalysis is broadly used in various fields but generally
applied in media with high ion strength. Here, we propose the exploitation
of enzymatic catalysis in ultra-low ion strength media to induce ion
strength increase for developing a novel impedance biosensing method.
Avian influenza virus H5N1, a serious worldwide threat to poultry
and human health, was adopted as the analyte. Magnetic beads were
modified with H5N1-specific aptamer to capture the H5N1 virus. This
was followed by binding concanavalin A (ConA), glucose oxidase (GOx),
and Au nanoparticles (AuNPs) to create bionanocomposites through a
ConA–glycan interaction. The yielded sandwich complex was transferred
to a glucose solution to trigger an enzymatic reaction to produce
gluconic acid, which ionized to increase the ion strength of the solution,
thus decreasing the impedance on a screen-printed interdigitated array
electrode. This method took advantages of the high efficiency of enzymatic
catalysis and the high susceptibility of electrochemical impedance
on the ion strength and endowed the biosensor with high sensitivity
and a detection limit of 8 × 10–4 HAU in 200
μL sample, which was magnitudes lower than that of some analogues
based on biosensing methods. Furthermore, the proposed method required
only a bare electrode for measurements of ion strength change and
had negligible change on the surficial properties of the electrode,
though some modification of magnetic beads/Au nanoparticles and the
construction of a sandwich complex were still needed. This helped
to avoid the drawbacks of commonly used electrode immobilization methods.
The merit for this method makes it highly useful and promising for
applications. The proposed method may create new possibilities in
the broad and well-developed enzymatic catalysis fields and find applications
in developing sensitive, rapid, low-cost, and easy-to-operate biosensing
and biocatalysis devices.