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Herein, π-conjugated polypyrene network (CPN) was synthesized by Suzuki-Miyaura polycondensation that exhibited high electrochemiluminescence (ECL) emission. The cross-linked network structure eliminates the aggregation-induced quenching effect of pyrene through steric hindrance. On the one hand, the extended π-conjugated backbone facilitated the acceleration of charge transfer and improved the stability of free radicals in the redox process, and on the other hand, by virtue of the porous structure, the coreactant and electrolyte could diffuse rapidly and fully penetrate into the polymer interior, thus effectively improving the ECL efficiency of the CPN. In view of the excellent ECL performance, an ECL biosensor for the ultrasensitive detection of the lung cancer biomarker microRNA let-7a was constructed by using CPN as a novel ECL probe in combination with a target-triggered rolling circle amplification strategy that exhibited a linear range from 1 aM to 10 pM with a low detection limit of 0.33 aM. In a word, this work provides an effective method to improve the ECL strength of polymers and opens up new prospects for developing new ECL emitters. • The high emission properties of conjugated polypyrene network were explored to construct an ECL biosensor. • Combination with RCA improved the sensitivity and specificity of miRNA let-7a detection. • This work presented a novel strategy to overcome the ACQ effect of PAHs. • This work provided a promising ECL platform for bioanalysis. [ABSTRACT FROM AUTHOR]

Electrochemiluminescence of lanthanide coordination polymers (LCPs) has drawn researchers' torrential interest attributed to their congenital standout optical properties. Herein, a novel electrochemiluminescent (ECL) emitter LCPs Tb-norfloxacin (Tb-NFX) was firstly reported, which originated from that NFX transferred excited state energy to Tb3+ by chelating antenna effect. Moreover, a creative ratiometric ECL biosensor was established based on an emerging pendant antenna effect mechanism between luminol and Tb-NFX. Specifically, Tb-NFX was immobilized on the electrode surface and SiO 2 nanostars@luminol was introduced onto the immunosensor by the sandwich-typed immunoassay. In view of this, the luminol transferred energy to the Tb-NFX and potential resolved ratiometric strategy was implemented for self-calibrated assay target. This work innovatively demonstrates that the development of new ECL luminophores through chelating antenna effect and the establishment of a dual-potential ECL ratio measurement strategy powered by pendant antenna effect are feasible, further extending the application of LCPs in ECL immunoassays and provides new directions for the construction of ECL ratio pairs. • A lanthanide coordination polymers ECL emission is ignited based on the chelating antenna effect. • An innovative approach to first constructing ratiometric ECL system derived from the pendant antenna effect. • This strategy offers perspectives in future design of highly accurate ratiometric ECL sensing platforms. [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]

• AgI nanohybrids was proposed as a photothermal agent. • Signal amplification was achieved by photothermal effect. • A multifunctional probe was performed by the precise controlling of NIR laser. Herein, a photothermal in-situ amplified electrochemical immunoassay based on multifunctional probe for detecting autoimmune hepatitis marker was constructed. The immunoassay followed a sandwich protocol, helical carbon nanotubes (HCNTs) and polyaniline (PANI) composite provided a desirable substrate for the immobilization of massive primary antibody (Ab 1). Subsequently, the multifunctional probe, by utilizing Chitosan (CS) modified AgI nanohybrids (AgI NHs) labeled secondary antibody (Ab 2), were simply designed for the first time. To be specific, AgI NHs were not only directly served as signal readout, but also as amplifier further enhanced electrochemical signal. Under the near-infrared (NIR) laser irradiation, electrochemical reaction was significantly accelerated on electrode in situ due to the extraordinary photothermal conversion capability of AgI NHs. Therefore, the evidently improved sensitivity together with enhanced signal-to-noise ratio of immunoassay was achieved in the short time by precise-controlling of NIR laser irradiation. Under the optimal conditions, the developed electrochemical immunoassay realized sensitive and specific detection of autoimmune hepatitis marker from 10−4 ng/mL to 1 ng/mL with low detection limit of 3.3 × 10-5 ng/mL. Importantly, this work provided a promising prospect for the application of photothermal effect coupled with electrochemical immunoassay and opened up a new pathway for signal amplification. [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]