Search

Abstract: A novel electrogenerated chemiluminescence (ECL) assay for sensitive determination of thrombin is designed employing CdSe/ZnS quantum dots served as an ECL label. This ECL sensor is fabricated on graphene modified glassy carbon electrode which is then covered with a low surface coverage of gold nanoparticles (AuNPs). An aptamer is used to selectively recognize the target. The thiol-terminated aptamer is first immobilized on AuNPs/graphene modified electrode, and then thrombin is imported to form the aptamer–thrombin complexes. After blocking the nonspecifically bound oligonucleotides with MCH solution, another CdSe/ZnS quantum dots modified aptamer is hybridized with the free thiol-terminated aptamer to form a DNA complexe. A decreased ECL signal is observed upon recognition of the target thrombin. The integrated ECL intensity versus the concentration of thrombin is linear in the range from 0.01 to 50nM. The detection limit is 10fM. The present aptasensor also exhibits excellent selectivity, stability and reusability. This sensing system can provide a promising label-free model for aptamer-based compounds sensitive detection. [Copyright &y& Elsevier]

In this study, a hierarchically porous Zr‐MOF‐labeled electrochemical biosensor for the detection of Adenosine Triphosphate (ATP) was constructed using polyethylenimine‐reduced graphene oxide/Gold nanowire nanocomposite (PEI‐rGO/AuNWs) and exonuclease I (Exo I) assisted target recycling strategy. PEI‐rGO/AuNWs nanocomposite not only favor the immobilization of c‐DNA but also facilitate the electron transfer and elevate the electrode surface area. In addition, hierarchically porous Zr‐MOFs (HP‐UiO‐66), high stability and large mesoporous property, could load more signal molecules. In the presence of ATP, ATP aptamer was released from the c‐DNA, thus introducing MB@Zr‐MOF‐s‐DNA onto the electrode surface. Meanwhile, Exo I selectively digested the aptamer which bound with ATP, the released ATP participated new binding with the rest aptamer. Therefore, a significant increase in MB current intensity was observed. Under optimal conditions, the proposed aptasensor showed excellent performance with a linear range from 10−6 μM to 10 μM and a detection limit of 3.76×10−8 μM by differential pulse voltammetry. In addition, the proposed biosensor showed an outstanding performance with reproducibility, stability and anti‐interference ability, and was applied to the determination of ATP in real samples. [ABSTRACT FROM AUTHOR]

Lead ion pollution has become a serious public health concern worldwide. Therefore, sensitive detection of Pb2+ is critical to control lead pollution, assess risks, and safeguard the health of vulnerable populations. This study reports a highly sensitive labelling-free electrochemical aptasensor for Pb2+ detection. The aptasensor employs silver-platinum nanoparticles/graphene oxide (AgPt/GO) and Exonuclease III (Exo III) for signal amplification. GO provides high surface area and conductivity for immobilizing AgPt NPs, facilitating the immobilization of aptamer (Apt) probes on the electrode surface. Exo III enzymatically cleaves DNA strands on the electrode surface, releasing DNA segments to amplify the signal further. The synergistic amplification by AgPt/GO and ExoIII enables an extremely wide linear detection range of 0.05 pM–5 nM for Pb2+, with a low detection limit of 0.019 pM. Additionally, the G-quadruplex structure ensures excellent selectivity for Pb2+ detection, resulting in high reproducibility and stability of the aptasensor. The aptasensor was successfully applied to detect spiked Pb2+ in tap water samples, achieving recovery rates ranging from 96 to 108.4 %. By integrating nanomaterials, aptamers and enzymatic amplification, the aptasensor facilitates highly sensitive and selective detection of Pb2+, demonstrating potential for practical applications in environmental monitoring. [Display omitted] • Silver-platinum nanoparticles/graphene oxide nanocomposite modified electrode. • Exo III cycling amplification strategy to enhance sensitivity. • The aptasensor has a wide linear detection range and an ultralow limit of detection. • Excellent selectivity, stability and reproducibility of the aptasensor demonstrated. • Successful application in detecting spiked Pb2+ in tap water samples. [ABSTRACT FROM AUTHOR]

Herein, PtPd nanoparticles compound polyethyleneimine-functionalized reduced graphene oxide (PtPd NPs/PEI-rGO) was used as the substrate material, Exonuclease III (Exo III)-assisted triple-amplified was integrated into electrochemical platform for the detection of deoxynivalenol (DON). PtPd NPs/PEI-rGO as the substrate material increased the surface area of the electrode and improved the conductivity of the electrode. The specific binding of the DON and the aptamer triggered Exo III-assisted cyclic amplification in sample solution and generated trigger (Tr) (cycle I). The hybridization of Tr and Locking probe (LP) activated DNA Walker (W-DNA) (cycle II). Then, W-DNA run continuously with the assistance of Exo III, eventually the current signal was decreased (cycle III). However, in the absence of DON, DNA machine was not driven and the electric signal was relatively high. Under optimal conditions, the detection limit of the aptasensor is 6.9 × 10−9 mg mL−1, and the detection range from 1 × 10−8 mg mL−1 to 1 × 10−4 mg mL−1. In addition, the stability, reproducibility, and real sample detection ability of the aptasensor were studied and obtained satisfactory results. • PtPd NPs/PEI-rGO was used as the substrate material. • DON aptamers were used as biological recognition elements to ensure the selectivity of aptasensor. • The DNA walking machine assisted by Exo Ⅲ realizes effective signal amplification. [ABSTRACT FROM AUTHOR]

Herein, an aptasensor based on Pb2+ dependent DNAzyme driven DNA Walker with the triple amplification signal strategy was developed for ultrasensitive detection of enrofloxacin (ENR). The composite of Au & Pt coated hollow cerium oxide (AuPt@h-CeO 2), and polyethyleneimine (PEI) functionalized molybdenum disulfide (PEI-MoS 2) were used as the substrate material to increase the specific surface area of the electrode and attach more DNA probes. In the presence of ENR, the aptamer can break away from the double-stranded structure, releasing DNAzyme capable of cleaving circular RNA with the help of Pb2+, which in turn will generate a large number of capture probes that bind the signal probes. In-situ reduced gold nanoparticles coated bimetallic metal-organic framework (Au@ZnNi-MOF) as signal labeled to catalyze thionine (Thi) to amplify the signal, which could be observed a significant electrochemical signal in square wave voltammetry (SWV). As expected, under the optimal conditions, the current in SWV is linearly related with the concentration of ENR in the range of 5.0 × 10−6 to 1.0 × 10−2 ng/mL with a limit of detection of 1.02 × 10−7 ng/mL. Further, it has been successfully used in real environmental water and milk samples and showed satisfactory performances. [ABSTRACT FROM AUTHOR]

• A "signal off" electrochemical aptasensor strategy for the detection of ENR is constructed. • AuNPs/Ni-MOF for electrode sensing platform preparation are used for catalyst thionine and signal amplification. • AuTSs acts as a bridge between cDNA and thionine, speeding up electron transfer. • The protocol possesses accepted specificity and can be applied in real sample. In this project, we developed an electrochemical aptamer sensor based on the coordinated catalysis toward thionine (Thi) of nickel metal-organic framework (Ni-MOF) and gold nanoparticles (AuNPs) to sensitively detect the enrofloxacin (ENR), which belonged to a third-generation quinolone antibiotic for treat diseases caused by bacteria. In order to improve the analytical performance of the sensor, Ni-MOF and gold AuNPs, as the substrate material, could increase the load of the aptamer (Apt) and synergistically catalyze thionine (Thi). Therefore, ultrathin sheets of gold triangular nanosheets (AuTNSs) were prepared as signal labeling materials, which were loaded with a large amount of Thi and complementary deoxyribonucleic acid (cDNA). With the help with Ni-MOF and AuNPs catalysis toward Thi, under optimal conditions, the aptasensor exhibited a massive detection range of 1×10−2 pg·mL−1 to 1×103 pg·mL−1 (S/N = 3) and a detection limit of 5.6×10−3 pg·mL−1 for ENR. Meanwhile, the proposed sensor has a high sensitivity, satisfactory repeatability and long-time stability, and could be well applied to the detection of food samples. [ABSTRACT FROM AUTHOR]

In view of the urgent need to determine polychlorinated biphenyls (PCBs) in the environment, we report a simple and sensitive electrochemical aptasensor to detect 3,3′,4,4′-tetrachlorobiphenyl (PCB77) based on Exonuclease III-powered Deoxyribonucleic Acid (DNA) walking machine using poly (diallyldimethylammonium chloride) (PDDA), which was functionalized hollow porous graphitic carbon nitride/ Ni-Co hollow nanoboxes/ Au-Pd-Pt nanoflowers composite material. Upon the addition of PCB77, the specific binding between PCB77 and the aptamer (Apt) could trigger the Exo III-assisted cyclic amplification process and release unlocking probes to deblock the Swing arm/Blocker duplex. Finally, the hybridized hairpin 3 (HP3), a short oligonucleotide, was left on the electrode via Exo III digestion of hybridized HP2, and thus a strong methylene blue (MB) signal was obtained. As expected, the proposed aptasensor exhibits exceptional PCB77 detection performances with a very low detection limit of 5.13 pg/L and a wide linear range of 0.01–100 ng/L based on the calibration curve. Moreover, the aptasensor presents a high level of selectivity and stability, with an acceptable degree of reproducibility. The results of this study have indicated that the proposed aptasensor has great potential application prospects, as demonstrated by its successful use in real environmental water samples. [Display omitted] • The HP-C 3 N 4 /Ni-Co NBs/Au-Pd-Pt NFs nanocomposite is employed as sensing platform. • DNA walking machine improved the sensitivity of the aptasensor obviously. • Aptasensor for PCB77 detection in the real samples can be achieved. • The proposed sensor showed a low detection limit of 5.13 pg/L. [ABSTRACT FROM AUTHOR]