Herein,
a hand-drawing paper-based bipolar electrode (BPE) electrochemiluminescence
(ECL) platform for M.SssI methyltransferase (M.SssI MTase) assay was
proposed via employing high electrocatalytic Pt@CeO2 as
an ECL co-reaction accelerator and pencil-drawing graphite electric
circuits as wires and electrodes. Notably, the introduction of pencil-drawing
trace not only simplified the manufacturing process but also reduced
the cost and saved fabricating time. Meanwhile, Pt@CeO2 with good electrocatalytic activity and satisfactory chemical stability
was used at the anode of the closed BPE-ECL device to accelerate the
oxidation rate of uric acid. Due to the balanced charges of the bipolar
electrode, the ECL response of the MnS: CdS@ZnS/S2O8
2– system emitted on the cathode was enhanced.
In situ growth of gold nanoparticles in the two electrode areas was
convenient for DNA immobilization. With the above points in mind,
the specific DNA double strands functionalized via Pt@CeO2 were employed to identify M.SssI MTase. The unmethylated DNA double
strands were cut by HpaII endonuclease, resulting
in the quenching of the ECL signal. Under the optimal conditions,
sensitive detection of M.SssI MTase in a wide linear range of 0.01–100
U·mL–1 with a satisfactory detection limit
of 0.008 U·mL–1 was realized. The reliable
and versatile BPE-ECL tool for the determination of M.SssI MTase with
easy-to-operate pencil-drawing traces and independent solution systems
provides a new opportunity to develop paper-based devices applied
in early disease diagnosis and pathogenesis research.
Currently, developing versatile, easy-to-operate, and effective signal amplification strategies hold great promise in photoelectrochemical (PEC) biosensing. Herein, an ultrasensitive polyvinylpyrrolidone-treated In 2 S 3 /WO 3 (In 2 S 3 -P/WO 3 )-functionalized paper-based PEC sensor was established for sensing ochratoxin A (OTA) based on a target-driven self-feedback (TDSF) mechanism enabled by a dual cycling tactic of PEC chemical−chemical (PECCC) redox and exonuclease III (Exo III)-assisted complementary DNA. The In 2 S 3 -P/WO 3 heterojunction structure with 3D open-structure and regulable topology was initially in situ grown on Au nanoparticlefunctionalized cellulose paper, which was served as a universal signal transducer to directly record photocurrent signals without complicated electrode modification, endowing the paper chip with admirable anti-interference ability and unexceptionable photoelectric conversion efficiency. With the assistance of Exo III-assisted cycling process, a trace amount of OTA could trigger substantial signal reporter ascorbic acid (AA) generated by the enzymatic catalysis of alkaline phosphatase, which could effectively provoke the PECCC redox cycling among the tris(2-carboxyethyl)phosphine acid, AA, and ferrocenecarboxylic at the In 2 S 3 -P/WO 3 photoelectrode, initiating TDSF signal amplification. Based on the TDSF process induced by the Exo III-assisted recycling and PECCC redox cycling strategy, the developed paper-based PEC biosensor realized ultrasensitive determination of OTA with persuasive selectivity, high stability, and excellent reproducibility. It is believed that the proposed paper-based PEC sensing platform exhibited enormous potential for the detection of other targets in bioanalysis and clinical diagnosis.
In vitro biosensing chips are urgently needed for early-stage
diagnosis
and real-time surveillance of epidemic diseases. Herein, a versatile
zone with photothermal effects is implanted in the miniature space
of a collapsible lab-on-paper photoelectrochemical biosensor for on-site
detection of microRNA-141 in body fluids, which can flexibly interconnect
the traditional photocurrent signal with functional temperature response.
The visualized thermoresponsive results are enhanced by the exciton
energy conversion between Fe3O4 nanoparticles
(Fe3O4 NPs) and formed Prussian blue nanoparticles
under near-infrared irradiation, which not only presents heat energy
gradient variations but also generates color changes. Significantly,
the controlled release of Fe3O4 NPs is actuated
by a target-triggered enzyme assist strand displacement cycle strategy
to efficiently improve the accuracy of target temperature signal prediction,
which can concurrently mediate photoelectric signal attenuation via
promoting the rapid recombination of photoexcited charge carriers
on the CuInS2/CoIn2S4 electrode surface,
affording dependable ultrasensitive detection results. Benefitting
from the ingenious design of the versatile thermoresponsive-photoelectric
sensing platform, the preliminary screening and ultrasensitive quantitative
analysis can be simultaneously achieved in a single-drop sample. As
a consequence, speedy prediction results and satisfied monitoring
data are acquired in the ranges of 0.5 pM to 2 nM and 0.001 pM to
5 nM by measuring the temperature change and photocurrent intensity.
By right of these advantages, such research paves a prospective paradigm
for the manufacture of a visual, rapid, broad-spectrum, and reliable
real-time surveillance platform, which allows it to be a promising
candidate for epidemic disease home diagnosis and intelligent diagnosis.
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