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A burgeoning diversified closed bipolar electrochemiluminescent (d-BPE-ECL) based on photothermal amplification biosensor via the thermophysical and photochemical properties of niobium carbide Mxene quantum dots (Nb 2 C MQDs) has been proposed. The device consists of three components: separated intermediate recognition, cathodic catalytic hydrogen evolution reaction (HER) and anodic ECL response channel. Wherein, the recognition compartment was innovatively designed as a temperature-sensitive conductivity modulated interface, and the introduction of photothermal material PDA@Nb 2 C MQDs through target mediated rolling circle amplification strategy increases the interface temperature under near-infrared light radiation, thereby enhancing the BPE current and leading to the amplification of the anode ECL signal of Nb 2 C MQDs. In addition, MoS 2 @Ni-Cu-P features excellent electrocatalytic activity, which can promote HER and thus accelerate electron transfer, further amplifying the ECL signal. Therefore, a highly sensitive d-BPE-ECL biosensor for hepatitis C virus envelope protein E2 detection with a linear range from 10 -4 to 10 ng/mL and detection limit of 3.3 × 10 -5  ng/mL was obtained. This work is expected to provide a new direction for exploring BPE multiple signal amplification strategy and broaden the application of BPE-ECL in bioassays., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Hong Dai reports financial support was provided by Quzhou University. Hong Dai reports a relationship with Quzhou University that includes: employment., (Copyright © 2023. Published by Elsevier B.V.)

Based on the highly specific interaction between concanavalin A (Con A) and glucose (Glu), a competitive electrochemiluminescence (ECL) biosensor was constructed for ultrasensitive detection of Con A. Nanocomposites with excellent electrocatalytic and photothermal properties were obtained by covalently bonding zinc oxide quantum dots (ZnO QDs) to vanadium carbide MXene (V2C MXene) surfaces. The modification of ZnO QDs hinders the aggregation of V2C MXene and increases the catalytic activity of oxygen reduction reaction, thus amplifying the luminol cathodic emission. In addition, the excellent photothermal performance of the V2C MXene-ZnO QDs can convert light energy into heat energy under the irradiation of 808 nm near infrared laser, thus increasing the temperature of the reaction system and accelerating the electron transfer process to realize the synergistic amplified homogeneous ECL system. This innovative work not only enriches the fundamental research on multifunctional MXene nanomaterials for biosensing, but also provides an effective strategy for ECL signal amplification. [ABSTRACT FROM AUTHOR]

• An ultrasensitive ratiometric ECL immunosensor was constructed to realize stratifin determination. • PFBT with anodic ECL signal and g-C 3 N 4 QDs with cathodic ECL signal were firstly used as a pair of luminophores to generate two ECL signals. • Two TiO 2 mesocrystals of the same type but with different structures were synthesized by controlling different calcination conditions. • Combining the ECL pair, TiO 2 mesocrystal pair and effective signal amplification tactics, an ratiometric ECL immunosensor was constructed. Stratifin (SFN) is considered to be a new biomarker of cancers. In clinical medicine, combining tissue chip technology and immunohistochemical methods qualitatively prove that the abnormal expression of SFN is related to cancer. However, the quantitative detection of SFN is rarely performed. Herein, an ultrasensitive ratiometric ECL immunosensor was constructed to realize SFN determination. A polyvinylpyrrolidone (PVP)-assisted synthesis of TiO 2 (PVP-TiO 2)@Poly[(9,9-dioctyfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadia-zol-4,8-diyl)] (PFBT) nanomaterial with anodic ECL signal and carbon-coated TiO 2 (C-TiO 2)-loaded graphitic carbon nitride quantum dots (g-C 3 N 4 QDs) with cathodic ECL signal were firstly used as a pair of luminophores to generate two potential-resolved ECL signals. PVP-TiO 2 provided a substrate for the immobilization of biomolecules. C-TiO 2 due to the high specific surface area loaded a large amount of g-C 3 N 4 QDs, thereby increasing the ECL intensity. Not only that, the heterojunction formed by semiconductors could also further enhance ECL signal. Impressively, PFBT-C-TiO 2 conjugation possessed outstanding photothermal property, which could serve as photothermal convertor device and accelerate the electrochemical mass transfer on the electrode surface, further amplified ECL signal. The ratiometric biosensor showed good linear response for SFN from 10−6ng mL–1 to 0.1 ng mL–1 with a detection limit of 0.33 fg mL–1. [ABSTRACT FROM AUTHOR]

• Photothermal enhanced ECL immunosensor was constructed for Thyroglobulin detection. • ZnO QDs acted as coreaction accelerator and the formed ternary system possessed high ECL efficiency. • Nb 2 CTx MXene not only be used as scaffold but serve as photothermal convertor device to increase electrode surface temperature. • This work provides an effective signal amplification strategy for constructing immunosensor. Herein, an ultrasensitive electrochemiluminescence (ECL) immunosensor based on a high performance probe of Nb 2 CTx MXene immobilized ZnO quantum dots (QDs) was constructed for Thyroglobulin (Tg) detection. ZnO QDs with good biocompatibility and catalytic property was for the first time utilized as coreaction accelerator in Ru(bpy) 3 2+/S 2 O 8 2− system and enhanced ECL signal. Specifically, ZnO QDs can facilitate S 2 O 8 2− reduction to generate more SO 4 −, and then reacted with cathodic radical of Ru(bpy) 3 2+, realizing 2-fold enhancement in ECL intensity. Additionally, Nb 2 CTx MXene possesses excellent properties and was used as prominent supporter, improving the loading capacity of Ru(bpy) 3 2+ and ZnO QDs, and accelerating the electron transfer, resulting in ECL signal enhancement. Furthermore, Nb 2 CTx MXene acted as temperature controller and increased the electrode surface temperature by converting laser energy into heat, further amplified ECL signal. Because of the high sensitivity, good specificity and favorable stability, the proposed immunosensor realized sensitive detection of Thyroglobulin and had a great application prospect in bioanalysis and clinical diagnosis. [ABSTRACT FROM AUTHOR]

• A biosensor was constructed for detection of exosomes by utilizing dual-modality probe of MXenes-BPQDs. • BPQDs as coreactant of Ru(dcbpy) 3 2+ was used to prepare self-enhanced BPQDs-Ru(dcbpy) 3 2+ composites with strong ECL signal. • MXenes-BPQDs with excellent photothermal properties were for the first time used as photothermal probe for bioanalysis. • This work used ECL/temperature dual signals to detect exosomes, making results more convincing. Exosomes are nanoscale extracellular vesicles and have proven to be an effective biomarker for early cancer diagnosis. In this work, an ECL and photothermal dual-mode biosensor was fabricated for exosomes detection by utilizing emerging materials black phosphorous quantum dots (BPQDs) and MXenes as signal amplifier. To be specific, BPQDs can catalyze the oxidization of Ru(dcbpy) 3 2+ and was for the first time used as coreactant, the prepared self-enhanced Ru(dcbpy) 3 2+@BPQDs ECL system can produce a strong ECL signal by reducing energy loss and shortening electron transfer distance. MXenes possess large specific surface area and outstanding conductivity, which was employed as supporter to increase the immobilization amount of Ru(dcbpy) 3 2+ and BPQDs, further enhanced ECL signal. Furthermore, BPQDs and MXenes both have excellent photothermal effect, which were dexterously used as thermal convertor device to develop photothermal biosensor for exosomes analysis. This work innovatively employed a dual-modality probe of MXenes-BPQDs to establish biosensor, which not only enriched the application of MXenes and BPQDs in biodetection but also provided an effective and reliable method for exosomes detection. [ABSTRACT FROM AUTHOR]