50 research outputs found
Determination of Percent Hemoglobin A1c Using a Potentiometric Method
We report a potentiometric method for measuring the hemoglobin
A1c (HbA1c, glycated hemoglobin) concentration, hemoglobin (Hb) concentration,
and percent HbA1c (%HbA1c) in human blood hemolysate. The %HbA1c is
important for diagnosis and management of diabetes mellitus. Alizarin
red s (ARS) is used as a redox indicator. Phenylboronic acid (PBA)
binds to both ARS and HbA1c via diol–boronic acid complexation.
The binding of PBA to ARS shifts its redox potential negatively. However,
when HbA1c competes with ARS for PBA binding, the solution potential
shifts positively. This shift is linked to the HbA1c concentration.
The concentration of Hb is determined by allowing it to react with
FeÂ(CN)<sub>6</sub><sup>3–</sup>. The potential shift arising
from the reduction of FeÂ(CN)<sub>6</sub><sup>3–</sup> by Hb
is proportional to the logarithm of the Hb concentration. The results
obtained for %HbA1c in human blood hemolysate are in good agreement
with those determined using a reference method
Paper-Based Electrochemical Sensing Platform with Integral Battery and Electrochromic Read-Out
We report a battery-powered, microelectrochemical sensing
platform
that reports its output using an electrochromic display. The platform
is fabricated based on paper fluidics and uses a Prussian blue spot
electrodeposited on an indium-doped tin oxide thin film as the electrochromic
indicator. The integrated metal/air battery powers both the electrochemical
sensor and the electrochromic read-out, which are in electrical contact
via a paper reservoir. The sample activates the battery and the presence
of analyte in the sample initiates the color change of the Prussian
blue spot. The entire system is assembled on the lab bench, without
the need for cleanroom facilities. The applicability of the device
to point-of-care sensing is demonstrated by qualitative detection
of 0.1 mM glucose and H<sub>2</sub>O<sub>2</sub> in artificial urine
samples
Paper-Based Electrochemical Sensing Platform with Integral Battery and Electrochromic Read-Out
We report a battery-powered, microelectrochemical sensing
platform
that reports its output using an electrochromic display. The platform
is fabricated based on paper fluidics and uses a Prussian blue spot
electrodeposited on an indium-doped tin oxide thin film as the electrochromic
indicator. The integrated metal/air battery powers both the electrochemical
sensor and the electrochromic read-out, which are in electrical contact
via a paper reservoir. The sample activates the battery and the presence
of analyte in the sample initiates the color change of the Prussian
blue spot. The entire system is assembled on the lab bench, without
the need for cleanroom facilities. The applicability of the device
to point-of-care sensing is demonstrated by qualitative detection
of 0.1 mM glucose and H<sub>2</sub>O<sub>2</sub> in artificial urine
samples
Paper-Based Electrochemical Sensing Platform with Integral Battery and Electrochromic Read-Out
We report a battery-powered, microelectrochemical sensing
platform
that reports its output using an electrochromic display. The platform
is fabricated based on paper fluidics and uses a Prussian blue spot
electrodeposited on an indium-doped tin oxide thin film as the electrochromic
indicator. The integrated metal/air battery powers both the electrochemical
sensor and the electrochromic read-out, which are in electrical contact
via a paper reservoir. The sample activates the battery and the presence
of analyte in the sample initiates the color change of the Prussian
blue spot. The entire system is assembled on the lab bench, without
the need for cleanroom facilities. The applicability of the device
to point-of-care sensing is demonstrated by qualitative detection
of 0.1 mM glucose and H<sub>2</sub>O<sub>2</sub> in artificial urine
samples
Three-Dimensional Paper Microfluidic Devices Assembled Using the Principles of Origami
We report a method, based on the principles of origami (paper folding), for fabricating three-dimensional (3-D) paper microfluidic devices. The entire 3-D device is fabricated on a single sheet of flat paper in a single photolithographic step. It is assembled by simply folding the paper by hand. Following analysis, the device can be unfolded to reveal each layer. The applicability of the device to chemical analysis is demonstrated by colorimetric and fluorescence assays using multilayer microfluidic networks
Paper-Based Electrochemical Sensing Platform with Integral Battery and Electrochromic Read-Out
We report a battery-powered, microelectrochemical sensing
platform
that reports its output using an electrochromic display. The platform
is fabricated based on paper fluidics and uses a Prussian blue spot
electrodeposited on an indium-doped tin oxide thin film as the electrochromic
indicator. The integrated metal/air battery powers both the electrochemical
sensor and the electrochromic read-out, which are in electrical contact
via a paper reservoir. The sample activates the battery and the presence
of analyte in the sample initiates the color change of the Prussian
blue spot. The entire system is assembled on the lab bench, without
the need for cleanroom facilities. The applicability of the device
to point-of-care sensing is demonstrated by qualitative detection
of 0.1 mM glucose and H<sub>2</sub>O<sub>2</sub> in artificial urine
samples
Electrocatalytic Reduction of Oxygen on Platinum Nanoparticles in the Presence and Absence of Interactions with the Electrode Surface
We
report that ultraviolet/ozone (UV/O<sub>3</sub>) treatment can
be used to remove sixth-generation, hydroxyl-terminated polyÂ(amidoamine)
(PAMAM) dendrimers from dendrimer-encapsulated Pt nanoparticles (Pt
DENs) previously immobilized onto a pyrolyzed photoresist film (PPF)
electrode. Results from X-ray photoelectron spectroscopy, scanning
transmission electron microscopy, and electrochemical experiments
indicate that removal of the dendrimer proceeds without changes to
the size, shape, or electrocatalytic properties of the encapsulated
nanoparticles. The UV/O<sub>3</sub> treatment did not damage the PPF
electrode. The electrocatalytic properties of the DENs before and
after removal of the dendrimer were nearly identical
High-Efficiency Generation-Collection Microelectrochemical Platform for Interrogating Electroactive Thin Films
Here we report on the development
of a high-efficiency, dual channel-electrode
(DCE) generation-collection system and its application for interrogating
redox-active surface-adsorbed thin films. DCE systems consist of two
electrodes configured on the base of a microfluidic channel. Under
laminar flow conditions, a redox reaction can be driven on the upstream
generator electrode, and the products carried by convection to the
downstream collector electrode where the reverse redox reaction occurs.
One significant outcome of this report is that simple fabrication
techniques can be used to prepare DCE systems that have collection
efficiencies of up to 97%. This level of efficiency makes it possible
to quantitatively measure the charge associated with redox-active
thin films interposed between the generator and collector electrodes.
This is important, because it provides a means for interrogating species
that are not in sufficiently close proximity to an electrode to enable
direct electron transfer or electroactive films adsorbed to insulating
surfaces. Here, the method is demonstrated by comparing results from
this indirect surface interrogation method, using FeÂ(CN)<sub>6</sub><sup>3–</sup> as the redox probe, and direct electroreduction
of Au oxide thin films. These experimental results are further compared
to finite-element simulations
Paper-Based SlipPAD for High-Throughput Chemical Sensing
We report a paper analytical device
(PAD) that is based on the
SlipChip concept. This SlipPAD enables robust, high-throughput, multiplexed
sensing while maintaining the extreme simplicity of paper-based analysis.
The SlipPAD is comprised of two wax-patterned paper fluidic layers.
By slipping one layer relative to the other, solutions wick simultaneously
into a large array of sensing reservoirs or sequentially into a large
array of channels to carry out homogeneous or heterogeneous assays,
respectively. The applicability of the device to high-throughput multiplex
chemical analysis is demonstrated by colorimetric and fluorescent
assays