Publications by authors named "Ruo Yuan"

599 Publications

Highly efficient electrochemiluminescence resonance energy transfer material constructed from an AIEgen-based 2D ultrathin metal-organic layer for thrombin detection.

Chem Commun (Camb) 2021 Apr;57(35):4323-4326

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.

A facile strategy to design a highly efficient electrochemiluminescence resonance energy transfer (ECL-RET) system was proposed by using an AIEgen-based 2D ultrathin metal-organic layer (MOL) to coordinatively immobilize energy donors and acceptors simultaneously, in which the distance between adjacent donor-acceptor pairs was precise and short for obtaining high ECL-RET efficiency.
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http://dx.doi.org/10.1039/d1cc00364jDOI Listing
April 2021

Co-catalytic Fc/HGQs/FeO nanocomposite mediated enzyme-free electrochemical biosensor for ultrasensitive detection of MicroRNA.

Chem Commun (Camb) 2021 Apr 27. Epub 2021 Apr 27.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.

Herein, a novel co-catalytic ferrocene/hemin/G-quadruplexes/Fe3O4 nanoparticles (Fc/HGQs/Fe3O4) nanocomposite was synthesized to significantly magnify the electrochemical signal of ferrocene (Fc) using the synergistic catalysis of hemin/G-quadruplexes (HGQs) and Fe3O4 nanoparticles as hydrogen peroxide enzyme mimics for the construction of ultrasensitive electrochemical biosensors. The fabricated electrochemical biosensor can achieve ultrasensitive detection of miRNA-155 ranging from 0.1 fM to 1 nM, as well as a limit of detection of 74.8 aM. This strategy provides a new route to exploring efficient signal labels for signal amplification and provides an impetus to find novel methods for the construction of biosensors for biological detection and the early clinic diagnosis of diseases.
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http://dx.doi.org/10.1039/d1cc01106eDOI Listing
April 2021

A novel self-enhanced carbon nitride platform coupled with highly effective dual-recycle strand displacement amplifying strategy for sensitive photoelectrochemical assay.

Biosens Bioelectron 2021 Apr 8;184:113227. Epub 2021 Apr 8.

Key Laboratory of Luminescence Analysis and Molecular Sensing, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, PR China. Electronic address:

In this work, a novel self-enhanced photoelectric active material, Na, K-codoped carbon nitride (NaKCN), was synthesized for constructing sensitive photoelectrochemical (PEC) biosensor to detect target miRNA-182-5p. Ingeniously, the NaKCN displayed glucose oxidase (GOx)-mimicking photocatalytic property, which catalyzed glucose to in situ generate high levels of HO as its own electron donor for enhancing photocurrent. Moreover, the Na, K co-doping could reduce energy gap of carbon nitride material, effectively improving the optical absorptivity and photocatalytic efficiency. Additionally, a novel highly effective dual-recycle TSD amplifying strategy was constructed to convert a small amount of target into plentiful two types of output DNAs labeling with sensitizer MB to enhance photocurrent of NaKCN. As a result, this PEC biosensor achieved a high sensitivity with low detection limit of 3.3 fM, which provided a new avenue for improving sensitivity of bioanalysis and diagnosis of diseases.
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http://dx.doi.org/10.1016/j.bios.2021.113227DOI Listing
April 2021

Ruthenium(II) Complex-Grafted Hollow Hierarchical Metal-Organic Frameworks with Superior Electrochemiluminescence Performance for Sensitive Assay of Thrombin.

Anal Chem 2021 04 6;93(15):6239-6245. Epub 2021 Apr 6.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.

Metal-organic frameworks (MOFs) with porous structures exhibit favorable promise in synthesizing high-performance electrochemiluminescence (ECL) materials, yet their micropores and narrow channels not only restrict the loading capacity of ECL luminophores but also constrain the diffusion of coreactants, ions, and electrons. Hence, we developed a new and simple hydrothermal etching strategy for the fabrication of a hollow hierarchical MOF (HH-UiO-66-NH) with a hierarchical-pore shell, which was employed as a carrier to graft Ru(bpy)(mcpbpy) (bpy = 2,2'-bipyridine, mcpbpy = 4-(4'-methyl-[2,2'-bipyridin]-4-yl) butanoic acid) onto the coordinatively unsaturated Zr nodes of HH-UiO-66-NH, creating the Ru-complex-grafted HH-UiO-66-NH (abbreviated as HH-Ru-UiO-66-NH). Impressively, the HH-Ru-UiO-66-NH presented brilliant ECL emission. On the one hand, the HH-UiO-66-NH with a hierarchical-pore shell and hollow cavity was conducive to immobilize the Ru(bpy)(mcpbpy) of large steric hindrance into the interior of the MOF, markedly improving the load number of luminophores. On the other hand, the hierarchical-pore shell of HH-UiO-66-NH permitted fast diffusion of coreactants, ions, and electrons that facilitated the excitation of more grafted luminophores and greatly enhanced the utilization ratio of ECL luminophores. Inspired by the superior ECL performance of HH-Ru-UiO-66-NH, an ECL sensing platform was constructed on the basis of HH-Ru-UiO-66-NH as an ECL beacon combining catalytic hairpin assembly as a signal amplification strategy, showing excellent selectivity and high sensitivity for thrombin determination. This proof-of-concept work proposed a simple and feasible hydrothermal etching strategy to construct hollow hierarchical MOFs that served as carrier materials to immobilize ECL luminophores, providing significant inspiration to develop highly efficient ECL materials and endowing hollow hierarchical MOFs with ECL sensing applications for the first time.
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http://dx.doi.org/10.1021/acs.analchem.1c00636DOI Listing
April 2021

A novel SERS substrate with high reusability for sensitive detection of miRNA 21.

Talanta 2021 Jun 24;228:122240. Epub 2021 Feb 24.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, PR China. Electronic address:

Electrochemistry combining with Surface Enhanced Raman Spectroscopy (EC-SERS) is a hot area which can achieve real-time analysis of the electrochemical product. In this work, a high-performance reusable Raman substrate was fabricated via electrochemical reduction for miRNA 21 assay. In this strategy, 2'-hydroxymethyl-3, 4-thylenedioxythiophene (EDOT-OH) was electropolymerized to form PEDOT-OH (Red), which acted as a part of SERS substrate and a Raman probe at the same time. The Raman intensity of PEDOT-OH was different between the reduction (Red) and oxidation state (Ox). When it is oxidized, the signal of the PEDOT-OH (Ox) on the electrode surface can be restored by applying a reduction voltage. In view of this feature, a Raman enhanced substrate displaying signal changes is constructed and the constructed Raman substrate can be recycled quickly and efficiently. Combining with double-amplification strategy, the SERS platform can detect miRNA 21 from 100 fM to 1 μM. The Raman substrate can be reused at least 15 times and solves the current problems of poor reusability and troublesome restoration of present reusable Raman substrate. As a result, it indicates that the reusable Raman substrate with high performance and non-destructive property will broaden the application of EC-SERS and SERS analysis.
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http://dx.doi.org/10.1016/j.talanta.2021.122240DOI Listing
June 2021

Engineering a high-efficient DNA amplifier for biosensing application based on perylene decorated Ag microflowers as novel electrochemiluminescence indicators.

Biosens Bioelectron 2021 Jun 21;182:113178. Epub 2021 Mar 21.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, PR China. Electronic address:

DNA-based amplifiers with high programmability and accurate molecular recognition ability have become a versatile platform for target amplification. However, the random diffusion of capture probes (CPs) in most DNA amplifiers limits the target recognition efficiency, affecting the limit of detection. Herein, a high-efficient DNA amplifier was developed by localizing the CPs consisted of the unique palindromic tails and target recognition sequences on Au nanoparticle modified magnetic beads (Au@MBs). In the presence of target K-ras gene, the CPs with high local concentration and orientation could capture the target efficiently to expose their palindromic tails, which could act as primers to trigger the polymerization for target recycling. More importantly, the polymerization products could involve in the next recycle and produce abundant mimic targets (MTs) continuously, thereby achieving the detection of trace K-ras gene. Meanwhile, a novel electrochemiluminescence (ECL) indicator of a thin-layer of perylene (Pe) molecules decorated Ag microflowers (Pe@Ag MFs) was obtained based on the reaction between the perylene cation radical (Pe) and Ag atoms. The obtained Pe@Ag MFs exhibited desirable ECL performance because (i) a thin-layer of Pe molecules could reduce the inner filter effect and inactive emitters, (ii) the Ag MFs as coreaction accelerator could react with SO to produce more SO and shorten the distance between Pe and SO to significantly enhance the ECL intensity of Pe with less energy loss. This work paves the way for the development of efficient amplification strategy and offers a paradigm for the preparation of high-efficiency ECL indicators.
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http://dx.doi.org/10.1016/j.bios.2021.113178DOI Listing
June 2021

A sensitive label-free photoelectrochemical aptasensor based on a novel PTB7-Th/HO system with unexpected photoelectric performance for C-reactive protein analysis.

Biosens Bioelectron 2021 Jun 13;181:113162. Epub 2021 Mar 13.

Chongqing Engineering Laboratory of Nanomaterials & Sensor Technologies, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, PR China. Electronic address:

Herein, a sensitive label-free photoelectrochemical (PEC) aptasensor was constructed for C-reactive protein (CRP) analysis based on a novel and efficient poly{4,8-bis[5-(2-ethylhexyl) thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]-thiophene-4,6-diyl} (PTB7-Th)/HO system with unexpected photoelectric performance. The proposed PTB7-Th/HO system without any sensitizer could surmount defect of the poor photoelectric conversion efficiency of PTB7-Th, leading to the unexpected 10-fold photocurrent enhancement compared to the common PTB7-Th/PBS system. The strong enhancement effect might originate from the special function of hydrogen peroxide (HO) towards PTB7-Th. On the one hand, HO as electron acceptor could continuously capture photogenerated electrons located at acceptor part of PTB7-Th, which would visibly improve the charge separation efficiency of PTB7-Th and the electron-receiving property of electrolyte solution, thus leading to the obviously enhanced photoelectric conversion efficiency (PCE). More importantly, HO as oxidant could oxidize PTB7-Th to obtain oxidation product of PTB7-Th (OPP) with carbonyl group and carboxyl group, and the electron cloud density in donor part of the OPP was higher than that of PTB7-Th, therefrom producing the stronger electron-donating property and higher photoelectrochemical (PEC) reaction efficiency. As a proof of concept, the proposed PTB7-Th/HO system was successfully applied in the construction of a label-free PEC aptasensor for sensitive analysis of CRP, which performed a wide detection range from 1 pM to 1000 nM with a low detection limit of 0.33 pM. This study demonstrated a novel approach to the rational design of photoelectric conversion system with high PEC performance and provided an inspired tack for the construction of high-efficiency photoelectric devices.
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http://dx.doi.org/10.1016/j.bios.2021.113162DOI Listing
June 2021

Development of Hollow Electrochemiluminescent Nanocubes Combined with a Multisite-Anchored DNA Nanomachine for Mycotoxin Detection.

Anal Chem 2021 03 19;93(12):5301-5308. Epub 2021 Mar 19.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.

Polycyclic aromatic hydrocarbons (PAHs) are regarded as promising electrochemiluminescent (ECL) emitters owing to their high quantum efficiency and inexpensive production. Despite the fact that the ECL properties of the pure PAH microcrystal (such as rubrene microcrystals, Rub MCs) have gained extensive attention, it is a challenge in controlling the morphology and size to reduce the inner filter effect. Herein, an advanced ECL emitter of palladium nanoparticle-functionalized hollow PAH-metal nanocubes was prepared by an in situ redox deposition method (the resultant nanocomposites were abbreviated as Pd-Rub-Ag@Au nanocubes). Specifically, the rubrene-decorated Ag@Au nanocubes (Rub-Ag@Au nanocubes) were prepared using the Ag@Au nanocubes as a template and a rubrene cation radical (Rub) as a reductant, and then Pd nanoparticles (Pd NPs) were in situ reduced on the surface of Rub-Ag@Au nanocubes. Impressively, compared with the Rub MCs, Pd-Rub-Ag@Au nanocubes showed uniform size and significantly enhanced ECL efficiency and intensity in the aqueous media. As a proof-of-concept, the Pd-Rub-Ag@Au nanocube-based ECL biosensing platform combined with a multisite-anchored DNA nanomachine was constructed for ochratoxin A (OTA, a type of mycotoxin) detection. The DNA nanomachine covered with high-density recognizing sequences could operate toehold-mediated strand displacement amplification on the sensing platform and promote the movement efficiency and velocity greatly. Due to the advanced performance of Pd-Rub-Ag@Au nanocubes and high recognition efficiency of the DNA nanomachine, the proposed biosensor for OTA detection can achieve a detection limit of 4.7 fg/mL ranging from 0.01 to 100 pg/mL, which offers an ingenious method for the further application of PAHs.
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http://dx.doi.org/10.1021/acs.analchem.1c00446DOI Listing
March 2021

Swing Arm Location-Controllable DNA Walker for Electrochemiluminescence Biosensing.

Anal Chem 2021 03 15;93(8):4051-4058. Epub 2021 Feb 15.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.

Here, we described a novel swing arm location-controllable DNA walker based on the DNA tetrahedral nanostructures (DTNs) for nucleic acid detection using the polycyclic aromatic hydrocarbon (PAH) microcrystals (TAPE-Pe MCs) consisting of the nonplanar molecular tetrakis(4-aminophenyl)ethene (TAPE) and planar molecular perylene (Pe) as electrochemiluminescence (ECL) luminophores. Specifically, the swing arm strands and track strands were fixed simultaneously on the DTNs to obtain the location-controllable DNA walker, which possessed an improved reaction efficiency compared to that of a fixed swing arm-based DNA walker due to the quantitative and orderly swing arm on the DTNs. On the other hand, the Pe microcrystals doped by TAPE molecules could decrease the π-π stacking of Pe molecules for the ECL efficiency enhancement, achieving a blue-shifted and intense ECL emission. Therefore, we defined this enhanced and blue-shifted ECL phenomenon as "inhibition of conjugation-driven ECL (IC-ECL)". To prove these principles, a location-controllable DNA walker-based ECL biosensor was developed with microRNA let-7a as target molecules. The ECL biosensor achieved a low detection limit of 4.92 fM within a wide linear range from 10 fM to 100 nM. This approach offers a new insight for ECL efficiency increase and location-controllable strategies with improved reaction efficiency, demonstrating potential in diagnostic analysis.
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http://dx.doi.org/10.1021/acs.analchem.0c05051DOI Listing
March 2021

Self-Assembly of Gold Nanoclusters into a Metal-Organic Framework with Efficient Electrochemiluminescence and Their Application for Sensitive Detection of Rutin.

Anal Chem 2021 02 11;93(7):3445-3451. Epub 2021 Feb 11.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.

Ligand-protected gold nanoclusters (Au NCs) are promising electrochemiluminescence (ECL) emitters because of their striking optical properties and excellent biocompatibility, but free vibration and rotation of their ligand result in low ECL efficiency, dramatically limiting their applications. Herein, using the ligand of Au NCs as one of the building units, a Au NC-based metal-organic framework (Au NC-based MOF) was constructed by the coordination-assisted self-assembly strategy, which not only impedes the ligand rotation-induced energy dissipation but also diminishes the self-quenching effect due to the spatial distribution of Au NCs. As a proof of concept, the prepared GSH-Au NCs@ZIF-8 gives rise to a 10-fold enhanced anodic ECL efficiency compared to that of densely aggregated GSH-Au NCs with triethylamine as the coreactant. Based on high ECL efficiency of GSH-Au NCs@ZIF-8, a "signal off" sensing platform was proposed with rutin as a model analyte, achieving a low detection limit of 10 nM. Therefore, the strategy paves an effective and alternative methodology to enhance ECL efficiency of metal NCs, considerably broadening their potential applications in sensing analysis, clinical diagnosis, and light-emitting devices.
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http://dx.doi.org/10.1021/acs.analchem.0c04682DOI Listing
February 2021

Highly Stable Covalent Organic Framework Nanosheets as a New Generation of Electrochemiluminescence Emitters for Ultrasensitive MicroRNA Detection.

Anal Chem 2021 02 2;93(6):3258-3265. Epub 2021 Feb 2.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.

A pyrene-based sp carbon-conjugated covalent organic framework (COF) nanosheet (Py-spc-CON) with strong and stable electrochemiluminescence (ECL) emission was constructed by C═C polycondensation of tetrakis(4-formylphenyl)pyrene (TFPPy) and 2,2'-(1,4-phenylene)diacetonitrile, which was employed as a highly efficient ECL emitter to fabricate an ECL biosensor for the first time. The Py-spc-CON exhibited higher ECL intensity and efficiency than those of TFPPy, bulk Py-spc-COF, and imine-linked pyrene COF, not only because the pyrene luminophores and aggregation-induced emissive luminogens (cyano-substituted phenylenevinylene) were topologically linked into Py-spc-CON, which greatly increased the immobilization amount of luminophores and decreased the aggregation-caused quenching effect and nonradiative transition but also because the porous ultrathin structure of Py-spc-CON effectively shortened transport distances of an electron, ion, and co-reactant (SO), which made more ECL luminophores be activated and thus efficiently increased the utilization ratio of luminophores. More interestingly, when BuNPF was introduced into the Py-spc-CON/SO system as a co-reaction accelerator, the ECL signal of Py-spc-CON was further amplified. As expected, the average ECL intensity of the Py-spc-CON/SO/BuNPF system was about 2.03, 5.76, 24.31, and 190.33-fold higher than those of Py-spc-CON/SO, Py-spc-COF/SO, TFPPy/SO, and imine-linked pyrene COF/SO systems. Considering these advantages, the Py-spc-CON/SO/BuNPF system was employed to prepare an ECL biosensor for microRNA-21 detection, which exhibited a broad linear response (100 aM to 1 nM) and a low detection limit (46 aM). Overall, this work demonstrated that sp carbon CONs can be directly used as a high-performance ECL emitter, thus expanding the application scope of COFs and opening a new horizon to develop new types of ECL emitters.
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http://dx.doi.org/10.1021/acs.analchem.0c04931DOI Listing
February 2021

Target-induced activation of polymerase activity for recycling signal amplification cascades for sensitive aptamer-based detection of biomarkers.

Analyst 2021 Mar 18;146(5):1590-1595. Epub 2021 Jan 18.

Key Laboratory of Luminescence Analysis and Molecular Sensing, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.

It is of great importance to develop biosensing methods for the sensitive and selective analysis of biomarkers at very low levels in biological samples. Using a new target-induced activation of the DNA polymerase activity for recycling amplification cascades, we describe an aptamer-based method for highly sensitive detection of platelet-derived growth factor BB (PDGF-BB) in human serums. The polymerase activity is initially inhibited by the binding of the polymerase to the enzyme aptamer sequence. PDGF-BB associates with and switches a PDGF-BB binding aptamer to trigger the release of an active polymerase, which further initiates the simultaneous recycling of the target PDGF-BB molecules and the enzyme aptamer sequence for the subsequent displacement of the fluorescently quenched probes to recover the fluorescence. Due to two recycling cascades, substantial fluorescence magnification is obtained for the highly sensitive detection of PDGF-BB with a low detection limit of 5.1 pM. Moreover, the potential applicability of this method for real samples was verified by determining PDGF-BB in diluted human serums, relying on the excellent specificity and selectivity of the aptamer. The demonstration of the PDGF-BB assay method here thus can be expanded for the construction of diverse sensing platforms for detecting different trace biomarkers with the integration of an elaborate design of the aptamer probes.
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http://dx.doi.org/10.1039/d0an02288hDOI Listing
March 2021

Two Birds with One Stone: Surface Functionalization and Delamination of Multilayered TiCT MXene by Grafting a Ruthenium(II) Complex to Achieve Conductivity-Enhanced Electrochemiluminescence.

Anal Chem 2021 01 2;93(3):1834-1841. Epub 2021 Jan 2.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.

Two-dimensional (2D) nanosheets have captured significant attention in constructing highly efficient electrochemiluminescent (ECL) materials because their high surface area and fully exposed postmodification sites could greatly increase the loading amount of luminophores. However, traditional 2D nanosheets as carriers exhibited natively poor electrical conductivity that restricted the electrochemical activation and the utilization ratio of ECL luminophores. Herein, to overcome this drawback, we utilized conductive 2D TiCT MXene nanosheets as carriers to graft Ru(bpy)(mcpbpy) (bpy = 2,2'-bipyridine, mcpbpy = 4-(4'-methyl-[2,2'-bipyridin]-4-yl) butanoic acid) via a dehydrative condensation reaction and electrostatic interaction. Interestingly, Ru(bpy)(mcpbpy) played the role of "two birds with one stone", where Ru(bpy)(mcpbpy) acted as both an ECL luminophore and an intercalation molecule to achieve surface functionalization and delamination of multilayered TiCT successfully, obtaining 2D ultrathin Ru-complex-grafted MXene nanosheets (Ru@MXene). Owing to the high load capacity and superior electrical conductivity of an ultrathin 2D MXene nanosheet, the obtained Ru@MXene exhibited a superb ECL emission. As expected, compared with the nonconductive 2D ultrathin metal-organic layers (MOLs) as carriers to graft Ru(bpy)(mcpbpy), the ECL intensity and ECL efficiency of Ru@MXene presented about 5-fold and 1.7-fold enhancement, respectively. Considering these advantages, Ru@MXene was applied to construct an ECL sensor for ultrasensitive determination of mucin 1 (MUC1), which displayed superb sensitivity (100 ag/mL to 10 ng/mL) with a low detection limit of 26.9 ag/mL. Overall, the conductivity-enhanced ECL based on Ru@MXene opened a fire-new chapter to develop splendent performance ECL emitters and shed new light on the application potential of conductive materials in the bioanalysis field.
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http://dx.doi.org/10.1021/acs.analchem.0c04782DOI Listing
January 2021

Kill Three Birds with One Stone: Poly(3,4-ethylenedioxythiophene)-Hosted Ag Nanoclusters with Boosted Cathodic Electrochemiluminescence for Biosensing Application.

Anal Chem 2021 01 9;93(2):1120-1125. Epub 2020 Dec 9.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.

Metal nanoclusters (NCs) have attracted extensive interest in electrochemiluminescence (ECL) field, but it is still a significant challenge to prepare high ECL efficiency NCs, which tremendously precludes their application in sensing and imaging. Herein, we report poly(3,4-ethylenedioxythiophene) (PEDOT) as a functional ligand for NCs with a "kill three birds with one stone" role, acting as a stabilizer like existing templates, excitingly, excellent electrical conductivity to accelerate the injection of interfacial electrons, and outstanding electrocatalytic activity toward coreactants (SO), which breaks the convention that traditional ligands act as a double-edged sword in ECL field. As an illustration, PEDOT-hosted Ag NCs were prepared with an unprecedented ECL intensity with SO as a cathodic coreactant, which indicates that this novel ligand strategy will bring exciting opportunities, not only in opening up new horizons for rational development of high ECL efficiency metal NCs but also in advancing their potential applications in light-emitting devices and clinical biosensing. As a proof of concept, the PEDOT-hosted Ag NCs were applied as neoteric ECL emitters to achieve sensitive detection of dopamine (DA), which showcased a wide linear response from 1 nM to 10 mM and a low detection limit of 0.17 nM.
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http://dx.doi.org/10.1021/acs.analchem.0c04165DOI Listing
January 2021

Two kinds of DNA enzyme-powered bidirectional one-dimensional DNA walking nanomachine for payload release and biosensing.

Biosens Bioelectron 2021 Mar 24;175:112848. Epub 2020 Nov 24.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, PR China. Electronic address:

Herein, we present a target-triggered bidirectional one-dimensional (1D) DNA walking nanomachine, built from a well-designed track, which could simultaneously move two different DNA walkers to the opposite direction along the track and release payload. This track is composed of a DNA walker station (chain S3) in the middle of track for storing two kinds of DNA walker (W1 and W2), and corresponding two kinds of payload conjugated DNA stators (chain S1, S2 and S4, S5) for the moving of walker on the two flanks of chain S3 respectively. Moreover, the chain S3 also serves as a target-assisted amplification platform based on a catalytic hairpin assembly (CHA)-like strategy. In the presence of target (nucleic acid), the dynamic assembly between hairpin (HP) and S3 is triggered for multiple recycling of target and releasing of W1 and W2. Since the W1 and W2 respectively correspond to 8-17 DNAzyme and 10-23 DNAzyme, they could cleave the RNA substrates with sequence specificity to move towards two opposite directions along the track at the same time, accompanying the release of payloads. Such a 1D DNA walking nanomachine is not only could propel the walker to move in two directions respectively but also improve the locomotion efficiency compared to the traditional single-directional 1D DNA walking nanomachine with the same amounts of stators. This concept of inducing the locomotion manner change on a 1D DNA device may provide a thought to facilitate the development of DNA dynamic nanomachines and intelligent nanosensors.
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http://dx.doi.org/10.1016/j.bios.2020.112848DOI Listing
March 2021

Targeted Delivery of DNA Framework-Encapsulated Native Therapeutic Protein into Cancer Cells.

ACS Appl Mater Interfaces 2020 Dec 30;12(49):54489-54496. Epub 2020 Nov 30.

Key Laboratory of Luminescence Analysis and Molecular Sensing, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.

A protein-based therapy is significantly challenged by the successful delivery of native proteins into the targeted cancer cells. We address this challenge here using an all-sealed divalent aptamer tetrahedral DNA framework (asdTDF) delivery platform, in which the protein drug is encapsulated inside the cavity of the framework stoichiometrically a reversible chemical bond. The ligase-assisted seal of the nicks results in highly enhanced TDF stability of the against nuclease digestion to effectively protect the therapeutic protein from degradation. In addition, the divalent aptamer sequences incorporated into the framework favor it with a target-specific and efficient delivery capability. Importantly, upon being readily delivered into the targeted cancer cells, endogenous glutathione can trigger the release of the native therapeutic protein from the TDF in a traceless fashion by cleaving the reversible chemical bond, thereby leading to effective apoptosis of the specific cancer cells.
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http://dx.doi.org/10.1021/acsami.0c17887DOI Listing
December 2020

Biodegradable nanoparticle-assisted and multiplexed imaging of asymmetric RNA expressions in live cells for precise cancer diagnosis and prognosis.

Nanoscale 2020 Dec 26;12(47):24100-24106. Epub 2020 Nov 26.

Key Laboratory of Luminescence Analysis and Molecular Sensing, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.

The simultaneous imaging of the dynamic expression variations of regulatory RNAs in cells, which remains a major challenge, has important applications in precise disease diagnosis, treatment and prognosis. Here, we describe the establishment of a biodegradable ZnO nanoparticle (NP)-assisted asymmetric amplification approach for the simultaneous imaging of microRNA-21 (miRNA-21) and programmed cell death 4 (PDCD4) mRNA at distinct expression levels in live cells. The DNA signal probe complexes are immobilized on the ZnO NPs and readily delivered into the target cancer cells via the endocytosis pathway. The acidic microenvironment in cancer cells leads to the dissolution of the ZnO NPs to release Zn ions and the intracellular miRNA-21 activates the Zn-dependent DNAzyme to cleave the substrate signal probes with the assistance of the Zn cofactor to show green fluorescence for imaging miRNA-21. Meanwhile, the PDCD4 mRNA can displace the other quenched signal probes to generate red fluorescence. Importantly, the PDCD4 mRNA sequences can be recycled and reused by using the DNAzyme-cleaved sequences as the fuel strands through two strand displacement reactions to yield amplified red fluorescence for detecting low levels of PDCD4 mRNA. Moreover, our approach can be used to evaluate the varied expression levels of miRNA-21 and PDCD4 mRNA responsive to different drugs in cells, reflecting its usefulness for precise cancer diagnosis and prognosis upon anticancer drug treatment.
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http://dx.doi.org/10.1039/d0nr07156kDOI Listing
December 2020

A synergistic promotion strategy remarkably accelerated electrochemiluminescence of SnO QDs for MicroRNA detection using 3D DNA walker amplification.

Biosens Bioelectron 2020 Nov 16;173:112820. Epub 2020 Nov 16.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, PR China. Electronic address:

Developing low-cost and efficient methods to enhance the electrochemiluminescence (ECL) intensity of luminophores is highly desirable and challenging. Herein, we develop a synergistic promotion strategy based on three types of co-reaction accelerators to achieve an efficient SnO quantum dots (SnO QDs)-based ternary ECL system. Specifically, the MnO nanoflowers (MnO NFs), Ag nanoparticles (Ag NPs) and hemin/G-quadruplex were rationally selected as co-reaction accelerators. Owing to the synergistic effect, the deft integration of three types of co-reaction accelerators enabled better structural stability, more exposed catalytic active sites, and faster charge transfer, thus more effectively facilitating the reduction of co-reactant (SO) compared with that of the single co-reaction accelerator. To demonstrate the practical utility of this principle, an "on-off-super on" ECL biosensor was constructed in combination with a 3D DNA walker, which showed a superior linear range (10 aM-100 pM) and a low detection limit (2.9 aM) for the highly-sensitive miRNA-21 detection. In general, this work firstly reported that three types of co-reaction accelerators were deftly integrated to remarkably amplify the ECL emission of SnO QDs, and provided brand-new perspectives for research on the ingenious design of the structure and component of highly efficient co-reaction accelerators.
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http://dx.doi.org/10.1016/j.bios.2020.112820DOI Listing
November 2020

Fullerenol as a photoelectrochemical nanoprobe for discrimination and ultrasensitive detection of amplification-free single-stranded DNA.

Biosens Bioelectron 2020 Nov 13;173:112802. Epub 2020 Nov 13.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, PR China. Electronic address:

Traditional approaches for nucleic acids detection require prior amplification of target genes, while nanomaterials-aided DNA biosensors are very magnificent but still suffer from the nanomaterial acquirement and limited sensitivity (above picomolar level). Herein, fullerenol C(OH), a representative fullerene derivative, was employed as a photoelectrochemical (PEC) nanoprobe to achieve discrimination and ultrasensitive detection of amplification-free single-stranded DNA (ssDNA) down to sub-femtomolar level. The bonded hydroxyl groups with intense density endowed fullerenol to directly recognize and capture ssDNA-AuNPs via the hydrogen bonding interactions (H-bonds), leading to a sharply decreased photocurrent with quenching efficiency up to 85%, which could be attributed to the photo-generated electrons on the conduction band of fullerenol (-4.66 eV) preferentially migrating to the Fermi level of AuNPs (-5.1 eV) rather than the electrode. In the presence of target gene (mutant human p53 gene fragment), the H-bonds between fullerenol and ssDNA were competitively depleted during the base pairing process of complete hybridization between ssDNA and target, making double-stranded DNA-AuNPs (dsDNA-AuNPs) depart so that the photocurrent powerfully recovered. On basis of the photocurrent variation before and after target introduction, this proposed simple, rapid and ultrasensitive PEC biosensor for amplification-free target gene detection illustrated a wide liner ranged from 1 fM to 100 pM and a detection limit of 0.338 fM. This work presented an ingenious strategy for the discrimination and ultrasensitive detection of nucleic acids, and the well-designed PEC biosensor was further conducive to the impetus of clinic diagnostics.
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http://dx.doi.org/10.1016/j.bios.2020.112802DOI Listing
November 2020

Liquid Phase Interfacial Surface-Enhanced Raman Scattering Platform for Ratiometric Detection of MicroRNA 155.

Anal Chem 2020 12 9;92(23):15573-15578. Epub 2020 Nov 9.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.

The self-assembly of gold nanoparticles (Au NPs) on a liquid phase interface is often employed as a surface-enhanced Raman scattering (SERS) platform with advantages of simple preparation, high reproducibility, and a defect-free character, but they are limited to only detect a target with Raman signals. To overcome this problem, microRNA 155 without a Raman signal can be detected by a liquid phase interfacial ratiometric SERS platform. Compared with the typical solid phase SERS platform, we propose a distinctive strategy not only owning the advantages of the liquid phase interfacial platform but also breaking the limitation of recent liquid-liquid interfacial SERS analysis. This platform presents a fabulous sensitivity with a limit of detection (LOD) of 1.10 aM for microRNA 155. By simply altering the duplex-specific nuclease (DSN) enzyme amplification, our strategy can realize detection of a variety of microRNAs, paving the way to practical applications of a liquid phase SERS platform.
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http://dx.doi.org/10.1021/acs.analchem.0c03633DOI Listing
December 2020

Enhancing photoelectrochemical performance of ZnInS by phosphorus doping for sensitive detection of miRNA-155.

Chem Commun (Camb) 2020 Nov 30;56(91):14275-14278. Epub 2020 Oct 30.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.

We report the synthesis of phosphorus-doped ZnInS (ZnInSP) materials through a solid/gas-phase reaction. ZnInSP shows enhanced photoelectrochemical (PEC) performance due to the improved photo-carrier separation efficiency achieved by substituting some of the sulfur with phosphorus. A PEC biosensor was further developed based on ZnInSP, which exhibits excellent analytical performance for miRNA-155.
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http://dx.doi.org/10.1039/d0cc06111eDOI Listing
November 2020

Ultrasensitive Electrochemiluminescence Biosensor Using Sulfur Quantum Dots as an Emitter and an Efficient DNA Walking Machine with Triple-Stranded DNA as a Signal Amplifier.

Anal Chem 2020 11 27;92(22):15112-15119. Epub 2020 Oct 27.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.

In this study, sulfur quantum dots (SQDs) with superior near-infrared electrochemiluminescence (ECL) performance were synthesized by the HO-assisted top-down approach. Through HO etching, the size and dispersity of SQDs were adjusted, reducing the aggregation-caused quenching effect and obviously promoting the ECL performance. Using the obtained SQDs as an emitter, a super-sensitive ECL biosensor of microRNA-21 (miRNA-21) detection was constructed, which was based on an efficient DNA walking machine with triple-stranded DNA (tsDNA) nanostructures as tracks. Compared with the common single-stranded DNA or double-stranded DNA, the tsDNA nanostructures on the electrode interface could avert probe entanglement and decrease local overcrowding effects. The walking efficiency of the DNA walking machine was also improved and the signal-amplification efficacy was greatly enhanced, which was benefited from the fact that tsDNA nanostructures were highly rigid scaffolds and provided orderly tracks for the DNA walking machine to walk. Thus, the designed ECL biosensor demonstrated outstanding performance for miRNA-21 detection in the concentration range of 20 aM to 1 nM with a low detection limit of 6.67 aM. Remarkably, this work enriched the application of pure element quantum dots in the ECL field and offered a new avenue for ultra-sensitive detection in clinical and biochemical analysis.
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http://dx.doi.org/10.1021/acs.analchem.0c03311DOI Listing
November 2020

Hydrophobic-Driven Electrochemiluminescence Enhancement Target-Induced Self-Enrichment for Ultrasensitive Bioassay.

Anal Chem 2020 11 26;92(22):15120-15128. Epub 2020 Oct 26.

Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.

Considering the central challenge of the simple and efficient strategy to generate sensitive analysis technology, herein, we proposed a novel electrochemiluminescence (ECL) strategy based on target-induced self-enrichment hydrophobic interaction to generate significant ECL enhancement for untrasensitive detection of clinical biomarkers with cardiac troponin I (cTnI) for early diagnosis of acute myocardial infarction (AMI) as a model. Typically, the first antibody of cTnI (fAb) was immobilized onto the as-prepared electrode surface with the titanium dioxide nanoflower and gold nanoclusters When there was target cTnI, it could be captured onto the electrode surface based on the specific antigen-antibody interaction to furtherly capture cholesterol-modified second antibody of cTnI to increase the hydrophobicity of the electrode surface, which could be employed for the self-enrichment of hydrophobic ECL luminophore, tris(2,2'-bipyridyl-4,4'-dicarboxylato) ruthenium(II), and coreactant, tripropylamine in the detection solution. Thus, an increased ECL emission could be achieved due to the increased concentration of ECL luminophore and coreactant, which was quantitatively related with the concentration of target cTnI. As expected, a higher sensitivity was obtained with a detection limit of 0.04 pg/mL based on simplest operations of the proposed strategy with target-induced self-enrichment hydrophobic interaction. Importantly, this hydrophobic interaction-based ECL strategy could be easily expanded to the bioassay of various biomarkers, providing an efficient tool for early clinical diagnosis of AMI and some other diseases.
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http://dx.doi.org/10.1021/acs.analchem.0c03394DOI Listing
November 2020

High-Efficient Electrochemiluminescence of BCNO Quantum Dot-Equipped Boron Active Sites with Unexpected Catalysis for Ultrasensitive Detection of MicroRNA.

Anal Chem 2020 11 15;92(21):14723-14729. Epub 2020 Oct 15.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P.R. China.

Herein, the boron radical active sites of boron carbon oxynitride quantum dots (BCNO QDs) are electrically excited to produce boron radicals (B) for catalyzing peroxydisulfate (SO) as a coreactant to accelerate the generation of abundant sulfate radicals (SO) for significant enhancement in the electrochemiluminescence (ECL) efficiency of BCNO QDs, which overcome the defect of traditional carbon-based QDs with low ECL efficiency. Impressively, under extremely low concentration of SO solution, the BCNO QDs/SO system could exhibit high ECL emission, realizing environmental friendliness and excellent biocompatibility for sensitive bioanalysis. As a proof-of-concept, BCNO QDs, a new generation of ECL emitters with high ECL efficiency, were successfully used in the ultrasensitive determination of microRNA-21, which pushes the exploration of new ECL emitters and broadens the application in the field of clinical diagnosis, ECL imaging, and molecular devices.
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http://dx.doi.org/10.1021/acs.analchem.0c03289DOI Listing
November 2020

Ultrasensitive Photoelectrochemical Assay for DNA Detection Based on a Novel SnS/CoO Sensitized Structure.

Anal Chem 2020 11 13;92(21):14769-14774. Epub 2020 Oct 13.

Key Laboratory of Luminescence Analysis and Molecular Sensing, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.

In this work, an ultrasensitive photoelectrochemical (PEC) assay was established for sensitive DNA detection based on a novel SnS/CoO sensitized structure as a photoactive matrix and benzo-4-chlorohexadienone (4-CD) precipitate as a signal quencher. Noticeably, the photoelectric conversion efficiency of the SnS/CoO sensitized structure was dramatically enhanced due to the effective sensitization of CoO toward SnS, thus attaining an intense photocurrent response, which was sixfold higher than that of pristine SnS. Additionally, with the assistance of Nt.BstNBI enzyme-assisted target cycling process, a limited amount of target DNA (a fragment of p53 gene) could be converted into extensive output DNA, which could hybridize with capture DNA to yield abundant DNA duplex for loading mimetic enzyme manganese porphyrin (MnPP). Subsequently, 4-chloro-1-naphthol (4-CN) could be catalyzed to form 4-CD precipitate by MnPP on the modified electrode surface with the existence of HO. Then, the 4-CD precipitate severely hampered electron transfer, causing a prominently diminished photocurrent response for DNA determination. The elaborated PEC assay not only extended the application of SnS in the PEC biosensing field but also manifested a wide linear range of 100 aM to 1 nM with a low detection limit of 30 aM, exhibiting enormous potential for the detection of various biomarkers or other targets in bioanalysis and disease diagnosis fields.
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http://dx.doi.org/10.1021/acs.analchem.0c03497DOI Listing
November 2020

The synchronization of multiple signal amplifications for label-free and sensitive aptamer-based sensing of a protein biomarker.

Analyst 2021 Jan;145(24):7858-7863

School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, PR China.

The abnormal variation of the mucin 1 (MUC1) protein level is associated with the development of multiple cancers, and the monitoring of trace MUC1 can be useful for early disease diagnosis. Here, on the basis of the synchronization of DNA-fueled sequence recycling and dual rolling circle amplification (RCA), the establishment of a non-label and highly sensitive fluorescent aptamer-based detection strategy for the MUC1 protein biomarker is described. The target MUC1 binds the aptamer hairpin probe and causes its structure switching to release an ssDNA tail to trigger the recycling of the complex via two toehold-mediated strand displacement reactions under assistance of a fuel DNA. Such a recycling amplification leads to the formation of a partial dsDNA duplex with two primers at both ends, which cooperatively bind the circular DNA ring template to start the dual RCA to produce many G-quadruplex sequences. The protoporphyrin IX dye further associates with the G-quadruplex structures to show a dramatically elevated fluorescent signal for sensitively detecting MUC1 with a low detection limit of 0.5 pM. The established aptamer-based detecting strategy is also highly selective and can realize assay of MUC1 in diluted human serums, highlighting its potential for the detection of different protein biomarkers at low contents.
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http://dx.doi.org/10.1039/d0an01491eDOI Listing
January 2021

Novel Single-Enzyme-Assisted Dual Recycle Amplification Strategy for Sensitive Photoelectrochemical MicroRNA Assay.

Anal Chem 2020 11 12;92(21):14550-14557. Epub 2020 Oct 12.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.

Herein, a novel single-enzyme-assisted dual recycle amplification strategy based on T7 exonuclease (T7 Exo) and a strand-displacement reaction (SDR) was designed to fabricate a photoelectrochemical (PEC) biosensor for sensitive microRNA-141 (miRNA-141) detection with the use of laminar bismuth tungstate (BiWO) as photoactive material. Compared with a traditional enzyme-assisted dual recycle amplification strategy, the presented method could effectively refrain the enzyme interference reaction, reduce environmental sensitivity, and save cost. Here, hairpin DNA1 (H1) decorated on magnetic beads (MB) hybridized with target miRNA-141 to form an H1/miRNA-141 heteroduplex. With the introduction of hairpin DNA2 (H2)-labeled SiO (H2-SiO), SDR was triggered between H2-SiO and H1, thus miRNA-141 was displaced from the H1/miRNA-141 heteroduplex and an H1/H2-SiO duplex was formed, realizing the reuse of the target. In the presence of T7 Exo, the H1/H2-SiO duplex was digested with the release of output DNA-SiO. To enhance the target conversion rate, H1-MB was intactly released and cycled, which could initiate more T7 Exo digestion and free abundant output DNA-SiO. Through such a process, a tiny miRNA-141 could induce substantial output DNA-SiO, effectively improving the target amplification efficiency and detection sensitivity of a PEC biosensor. Furthermore, BiWO was modified on an electrode to provide a superior initial PEC signal due to its excellent electronic transformation capacity. With the introduction of output DNA-SiO, the hairpin structure of H3 on the electrode was opened, making SiO close to the electrode surface, which significantly decreases the PEC signal. This work first established the PEC biosensor featuring a single-enzyme-assisted dual recycle amplification process for sensitive detection of biomarkers.
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http://dx.doi.org/10.1021/acs.analchem.0c02752DOI Listing
November 2020

Simple and Regulable DNA Dimer Nanodevice to Arrange Cascade Enzymes for Sensitive Electrochemical Biosensing.

Anal Chem 2020 10 30;92(20):14197-14202. Epub 2020 Sep 30.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.

Herein, a simple and regulable DNA dimer nanodevice was obtained by the assembly of two hairpin DNA monomers of H1 and H2 to control the distance between model enzymes horseradish peroxidase (HRP) and glucose oxidase (GOx) for sensitive electrochemical detection of microRNA. In detail, auto-terminated DNA polymerization reaction was designed on H1 and H2 monomers that decorated with HRP and GOx, respectively, to produce two half-released DNA monomers, which were spontaneously hybridized to each other, thereby obtaining a DNA dimer nanodevice with a rigid dsDNA linker between two DNA monomers. By varying the length of the dsDNA linker on the DNA dimer nanodevice, the distance between GOx and HRP had been regulated to the optimum and the most efficient enzyme cascade reaction was acquired for constructing a sensitive electrochemical microRNA-21 biosensor with a detection limit of 0.03 pM. In summary, the proposed DNA dimer nanodevice avoided the disadvantages of poor biocompatibility and controllability originated from traditional scleroid scaffolds and showed obvious advantages in terms of better assembly yield than previous complicated DNA scaffolds, which provided a novel strategy for developing a high-efficiency enzyme cascade catalytic system and showed great potential in other clinical diagnosis and bioanalysis application.
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http://dx.doi.org/10.1021/acs.analchem.0c03396DOI Listing
October 2020

Guanine-Lighting-Up Fluorescence Biosensing of Silver Nanoclusters Populated in Functional DNA Constructs by a pH-Triggered Switch.

Anal Chem 2020 10 21;92(19):13369-13377. Epub 2020 Sep 21.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.

Dark or weak-emissive DNA-harbored silver nanoclusters (AgNCs) can be remarkably lighted up when approaching to guanine bases. The resultant bright AgNCs acting as a fluorescent reporter are fascinating in biosensing. To explore the applicable guanine-enhanced emission of AgNCs for biosensing microRNA-155 (miR-155) as a model, here we designed a unique stem-loop hairpin beacon (HB) encoding with an miR-155-recognizable sequence and a AgNCs-nucleable template, as well as a hairpin helper tethering a partially locked guanine-rich (15-nt) tail (GH), while two identical cytosine-rich segments were inserted in HB and GH to merge for folding/unfolding of i-motif at changed pHs. Initially, the intact clusters populated in HB (HB/AgNCs) were almost nonfluorescent in a buffer (pH 7.0). Then, miR-155 was introduced to trigger a repeated hairpin assembly of HB and GH by competitive strand displacement reactions at decreased pH 5.0 within 10 min, consequently generating numerous duplex DNA constructs (DDCs). With the resultant template of pH-responsive i-motifs incorporated in DDCs, their folding at pH 5.0 brought the proximity of unlocked G overhang to the clusters in a crowded environment, remarkably lighting up the red-emitting fluorescence of HB/AgNCs (λ = 628 ± 5 nm) for amplified signal readout. About 3.5-fold enhancement of quantum yield was achievable using different variants of i-motif length and G position. Simply by adding OH, the configuration fluctuation of i-motifs was implemented for switchable fluorescence biosensing to variable miR-155. Based on a one-step amplification and signaling scheme, this subtle strategy was rapid, low-cost, and specific for miR-155 with high sensitivity down to 67 pM.
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http://dx.doi.org/10.1021/acs.analchem.0c02744DOI Listing
October 2020

In Situ Controllable Generation of Copper Nanoclusters Confined in a Poly-l-Cysteine Porous Film with Enhanced Electrochemiluminescence for Alkaline Phosphatase Detection.

Anal Chem 2020 10 18;92(19):13581-13587. Epub 2020 Sep 18.

Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.

Copper nanoclusters (Cu NCs) as emerging luminescent metal NCs are gaining increasing attention owing to the comparatively low cost and high abundance of the Cu element in nature. However, it remains challenging to manipulate the optical properties of Cu NCs. Unlike most dispersed Cu NCs, whose luminescence efficiency was restricted by nonexcited relaxation, the Cu NCs confined in a porous poly-l-cysteine (poly-l-Cys) film were generated controllably with enhanced electrochemiluminescence (ECL) by in situ electrochemical reduction. Specifically, poly-l-Cys provided a porous structure to regulate the generation of Cu NCs within its holes, which not only increased the restriction on the intramolecular vibration and rotation of the ligands but also expedited the electron transfer near the electrode surface, reflecting in an enhancement of the ECL signal and efficiency. As an application of the confined Cu NCs, an ECL biosensor with high performance was constructed skillfully for highly sensitive detection of alkaline phosphatase (ALP), which adopted Cu NCs as the ECL luminophore and poly-l-Cys as a coreaction accelerator in a novel ECL ternary system (Cu NCs/SO/poly-l-Cys). Furthermore, an ingenious target amplification based on the combination of a DNA walker and click chemistry was developed to convert ALP to DNA strands efficiently, achieving great improvement in the recognition efficiency. As a result, the biosensor had a low detection limit (9.5 × 10 U·L) and a wide linear range (10-10 U·L) for ALP detection, which showed great promise for the detection of non-nucleic acid targets and the diagnosis of diseases.
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http://dx.doi.org/10.1021/acs.analchem.0c03312DOI Listing
October 2020