Dual-reporter, electrochemical aptamer-based (E-AB) sensors achieve calibration-free measurement of multiple specific molecules in situ in the living body.
Electrochemical aptamer-based
(E-AB) biosensors suffer from sensor-to-sensor
signal variations due to the variation of the total number and the
heterogeneity of probes immobilized on the electrode surface, with
the former attracting more attention. As such, a calibration process
to correct for such variations is required for this type of sensor,
causing inconvenience and inaccessibility in harsh sensing environments
such as blood samples, which has dramatically limited the widespread
clinical use of biosensors. In response, here, we have adopted E-AB
sensors to achieve calibration-free measurements of small biological/drug
molecules. Specifically, we employ one probe-attached redox reporter
and a second intercalated redox reporter to generate two signals,
achieving good sensor-to-sensor reproducibility and thus obviating
the need for calibration. We first demonstrated the capability of
E-AB sensors for the accurate measurement of kanamycin, tobramycin,
and adenosine triphosphate (ATP) in phosphate-buffered saline (PBS)
buffer, achieving concentration ranges of approximately 4.7 ×
103-, 2.0 × 103-, and 12.7-fold, respectively.
Then, we applied this calibration-free approach to the measurement
of these three target molecules directly in undiluted serum, achieving
a concentration precision of a few micromolars.
The development of biosensors capable to achieve accurate and precise molecular measurements in the living body under pH-variable biological environments (e. g. subcellular organelles, biological fluids and organs) plays a...
Hybridization chain reaction (HCR) amplification strategy has been
extensively explored for the application of electrochemical DNA-based
sensors. Despite the enhancement in its sensitivity using the HCR,
such sensor platform exhibited significant sensor-to-sensor variations
in current due to variations in probe counts and lengths. To circumvent
this, we are developing here a calibration-free “O-N”
approach to generate a ratiometric, unitless value that is independent
of these variations. Specifically, this approach employs two types
of redox reporters, denoted as “One reporter” and “N
reporters”, with the former attached on the capture DNA and
the latter on H1 and H2 strands. By optimizing the attachment sites
of these reporters onto DNA strands, we demonstrate a significantly
enhanced sensitivity of such sensor platform by four orders of magnitude,
achieving accurate, calibration-free measurement of nucleic acids
including ctDNA directly in undiluted whole blood without the requirement
to calibrate each individual sensor.
Whole blood, as one of the most significant
biological fluids,
provides critical information for health management and disease monitoring.
Over the past 10 years, advances in nanotechnology, microfluidics,
and biomarker research have spurred the development of powerful miniaturized
diagnostic systems for whole blood testing toward the goal of disease
monitoring and treatment. Among the techniques employed for whole-blood
diagnostics, electrochemical biosensors, as known to be rapid, sensitive,
capable of miniaturization, reagentless and washing free, become a
class of emerging technology to achieve the target detection specifically
and directly in complex media, e.g., whole blood or even in the living
body. Here we are aiming to provide a comprehensive review to summarize
advances over the past decade in the development of electrochemical
sensors for whole blood analysis. Further, we address the remaining
challenges and opportunities to integrate electrochemical sensing
platforms.
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