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Serotonin is an essential neurotransmitter that regulates many physiological processes and is related to a variety of diseases. Herein, a novel electrochemiluminescence-resonance energy transfer (ECL-RET) aptasensor for serotonin detection was developed, with zinc-based metal-organic frameworks (Zn-MOFs) as an ECL donor and Pt@Cu 2 O cubic nanocrystals (CNs) as an acceptor. In the presence of target, numerous Pt@Cu 2 O CNs were brought to electrode surface through the catalytic hairpin assembly (CHA)-driven DNA walker, resulting in a significant inhibition of ECL signal. The efficient ECL-RET device exhibited a wide linear range for monitoring serotonin (10 -12 to 10 -6  M) and a low detection limit of 0.5 pM. Furthermore, satisfactory recoveries were obtained by using the aptasensor to monitor serotonin levels in serum and urine samples. The broadband absorption feature of Pt@Cu 2 O CNs, along with the extraordinary amplification effect of catalytic hairpin assembly (CHA)-driven DNA walking machine, provided a new route for the construction of efficient ECL-RET systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The demand for sensitive, portable, and non-destructive analysis of pathogenic bacteria is of significance in point-of-care diagnosis. Herein, we constructed a smart electrochemiluminescence (ECL) biosensor by integrating a flexible paper-based sensing device and a disposable three-electrode detecting system. Staphylococcus aureus (S. aureus)-responsive cellulose paper was prepared by employing aptamer as recognition element and a probe DNA (probe DNA-GOD) tagged with glucose oxidase (GOD) as a signal amplification unit. The formation of aptamer-S. aureus complex mediated the quantitative release of probe DNA-GOD. The remaining probe DNA-GOD on the paper-based aptasensor was then activated by glucose, which resulted in a significant decrease in ECL signal. To further improve the ECL performance of biosensor, a large number of Ru(bpy) 3 2+ molecules were embedded into porous zinc-based metal-organic frameworks (MOFs) to form Ru(bpy) 3 2+ functionalized MOF nanoflowers (Ru-MOF-5 NFs). Such biosensor enabled accurate, non-destructive, and real-time monitoring of S. aureus-contaminated food samples, opening a new avenue for sensitive recognition of pathogenic bacteria., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Sensitive and accurate quantification of pathogenic bacteria is vastly significant to the related food safety. Herein, a sensitive ratiometric electrochemical biosensor was developed for the detection of Staphylococcus aureus (S. aureus) based on dual DNA recycling amplifications and Au NPs@ZIF-MOF accelerator. Gold nanoparticles-loaded Zeolitic imidazolate metal-organic framework (Au NPs@ZIF-MOF) as electrode substrate possessed a large specific surface area for nucleic acid adsorption, and as an accelerator promoted the transfer of electrons. The strong recognition of aptamer to target S. aureus could initiate the padlock probe-based exponential rolling circle amplification (P-ERCA, as the first DNA recycling amplification), generating large numbers of trigger DNA strands. The released trigger DNA further activated the catalytic hairpin assembly (CHA, as the second DNA recycling amplification) on electrode surface. Consequently, P-ERCA and CHA continuously brought about one target to many signal transduction, leading to an exponential amplification. To achieve the accuracy of detection, the signal ratio of methylene blue (MB) and ferrocene (Fc) (I MB /I Fc ) was applied for intrinsic self-calibrating. Taking advantages of dual DNA recycling amplifications and Au NPs@ZIF-MOF, the proposed sensing system displayed high sensitivity for S. aureus quantification with a linear range of 5-10 8  CFU/mL, and the limit of detection was 1 CFU/mL. Moreover, this system represented excellent reproducibility, selectivity, and practicability for S. aureus analysis in foods., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

A novel portable and disposable bipolar electrode (BPE)-electrochemiluminescence (ECL) device was fabricated for fumonisin B 1 (FB 1 ) detection. BPE was fabricated by using MWCNTs and polydimethylsiloxane (PDMS) due to their excellent electrical conductivity and good mechanical stiffness. After the deposition of Au NPs on the cathode of BPE, the ECL signal could be improved 89-fold. Then a specific aptamer-based sensing strategy was constructed by grafting capture DNA on Au surface, followed by hybridizing with aptamer. Meanwhile, an excellent catalyst, Ag NPs was labeled on aptamer to activate oxygen reduction reaction, leading to a 13.8-fold enhancement in ECL signal at the anode of BPE. Under the optimal conditions, the biosensor exhibited a wide linear range of 0.10 pg/mL to 10 ng/mL for FB 1 detection. Meanwhile, it demonstrated satisfactory recoveries for real sample detection with good selectivity, making it to be a convenient and sensitive device for mycotoxin assay., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

A novel area controllable biosensing interface is designed on glassy carbon bead (GCB) and used for measurement of tetracycline (TET) in closed bipolar electrode-electrochemiluminescence (ECL) device. One face of GCB is modified with Au particles and the covered area is varied from 0 to 45.3% by tuning the external voltage during bipolar electrodeposition process in a home-made open bipolar electrochemical cell. It enables the conjugation of various amounts of biomolecules on Au/GCB. Then DNA walker and methylene blue (MB) labeled DNA (MB-DNA) are conjugated on Au surface for the following combination of aptamer. In the presence of target, aptamer partially hybridized with DNA walker will be released from Au surface, leading to the formation of dsDNA between DNA walker and MB-DNA. As a result, MB-DNA with recognition site for nicking endonuclease (Nb.BbvCI) in dsDNA is cleft into two segments by Nb.BbvCI. Meanwhile, the liberated DNA walker is triggered to continue the degradation of many MB-DNA. Due to the excellent electrochemical performance of MB, it is reduced at the cathode of BPE to amplify the ECL signal at the anode of BPE in a closed BPE-ECL platform. When the covered area of GCB by Au particles is enlarged from 10.1 to 45.3%, the change of ECL intensity could be increased 2.7-fold. The linear range for the detection of tetracycline is from 1 × 10 -12 to 1 × 10 -5  M with the detection limit of 6.0 × 10 -13  M. Hence, controllable sensing area on a single glassy carbon bead, the amplification effect of DNA walker and MB make this approach possess many advantages over traditional biosensor., (Copyright © 2019 Elsevier B.V. All rights reserved.)