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Iridium (Ir) complexes have gained remarkable development momentum as candidates for electrochemiluminescence, but their poor solubility in water media greatly limited their application in ECL area. Herein, a facile nanoprecipitation method by encapsulating tris(2-phenylpyridinato)iridium (Ir(ppy) 3) into pluronic block copolymers for preparing water-soluble Ir(III) complexes with high ECL emission efficiency was developed. Then, with F-127@Ir(ppy) 3 as the anode emitter and g-C 3 N 4 as the cathode emitter, a new ratiometric biosensor based on transition metal complexes was developed for the first time, which was used for ultra-sensitive detection of hepatitis C virus E2 protein. Notably, the ratiometric ECL signal could be mediated by using multifunctional Nb 2 C nanosheets (Nb 2 C NSs) with excellent electrocatalytic activity and superoxide dismutase activity, so as to enhance the ECL intensity of anode and quench the response of cathode ECL. Combining Nb 2 C NSs with the antibody and the specific recognition process, the proposed ECL ratio biosensor showed good performance for E2 with a linear range from 1 × 10−3 ng/mL to 1 × 102 ng/mL and a detection limit of 8.39 × 10−4 ng/mL. The work on designing water-soluble Ir (III) complexes with pluronic block copolymer provides an ingenious approach to broaden the application of poorly soluble complexes in bioassays. [ABSTRACT FROM AUTHOR]

Herein, an ultrasensitive label-free electrochemiluminescence (ECL) immunosensor based on electrocatalytic and photothermal amplification was constructed and was applied to detect Thyroglobulin (Tg). Single-walled carbon nanotube (SWCNTs) with charming merits was used as supporter for porous NiCo 2 O 4 nanosheets (pNiCo 2 O 4 NSs), the formed pNiCo 2 O 4 NSs/SWCNTs hybrids was utilized as an effective matrix and realized multiple signal amplification. To be specific, pNiCo 2 O 4 NSs/SWCNTs hybrids on the one hand can facilitate the electron transfer and enhance ECL signal. On the other hand can catalyze the oxygen evolution reaction (OER) to increase the concentration of dissolved O 2 for further strengthening ECL signal. What's more, the pNiCo 2 O 4 NSs/SWCNTs hybrids had a strong near-infrared harvesting capability, can convert laser energy into heat to increase the electrode surface temperature, resulting in the significant enhancement in ECL signal. Based on excellent properties of pNiCo 2 O 4 NSs/SWCNTs hybrids, a highly-efficient label-free ECL immunosensor was developed and exhibited a wide linear range (10−5 ng/mL to 100 ng/mL) and a low detection limit (3.3 × 10−6 ng/mL) for Tg determination, which was approximately 7.1 fold-lower than at room temperature. This work provided a new thought for high-performance ECL sensing platform construction. • A label-free ECL immunosenor based on electrocatalyticl and photothermal amplification was developed to detect Thyroglobulin. • The hybrids as sensing platform not only can catalyze OER process to generate more amounts of dissolved O 2 but increase the electrode surface temperature. • The constructed immunosensor exhibited high sensitivity and wider linear range. [ABSTRACT FROM AUTHOR]

Herein, a photothermal triggered multi-signal readout (MSR) system was innovatively established with great convenience for low-cost and sensitive point-of-care testing (POCT). In this sensing system, an intelligent multi-signal readout interface (MSRI) with multidimensional response-ability to thermal stimulus was developed and utilized as a sensing element. A bio-bar-code photothermal probe peptides@H 2 N-HCNTs acted as a target associated photothermal agent anchored on MSRI via competitive reaction. The multi-signal assay of target was realized under the driven of 808 nm laser, photo-to-thermal conversion effect of photothermal probe caused dramatically thermal energy increase on MSRI. As a result, the competitive recognition events were translated into several detectable signals on MSRI, including a local temperature elevation, a visual color change from blue to green as well as weight loss on MSRI, all of these signals were proportional to the target concentration. This assay has been successfully applied in field work for detecting zearalenone (ZEN), a common mycotoxin in grain food, with linear ranger from 10−7 ng/mL to 10−1 ng/mL and detection limits of 1.06 × 10−7 ng/mL. Combination of the different signal principles was expected to result in more reliable and precise results. Accordingly, this creatively designed MSR-system not only provided a platform for sensitive monitor of mycotoxin but also offered new method for reliable and affordable personal assays in daily life and low-resource setting. • A multi-signal readout system was proposed for sensitive point-of-care testing. • An interface with multidimensional response ability to thermal stimulus was utilized as a smart sensing element. • The bio-bar-code photothermal probe induced several detectable signal responses on MSRI. • The mutual calibration between different signals improved precision in positive judgments. • A common mycotoxins zearalenone was selected as a target analyte. [ABSTRACT FROM AUTHOR]

The development of convenient and sensitive multi-readout immunoassay is crucial but highly challenged for meeting the demand of exactness and diversity in early clinical diagnosis. Herein, a split-type multiple stimuli-responsive biosensor was outlined combined with the outstanding superiority of luminol probe-based electrochemiluminescence (ECL) strategy, mimicking enzyme-mediated colorimetric system and portable photothermal effect-induced temperature sensing. Especially, versatile MoS 2 nanosheets (MoS 2 NSs) with distinguished property not only acted as dual-promoter to improve the cathodic ECL of luminol because of its good electrocatalytic activity for dissolved O 2 and favorable photothermal effect for elevating electrode temperature, but also used as nanozyme to regulate subsequent split-type visual colorimetric sensing due to its peroxidase-like activity for the generation of oxidized 2,2′-azinobis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) in ABTS-H 2 O 2 colorimetric system. More importantly, the green oxidized ABTS (ABTS•+) also exhibited strong near-infrared (NIR) laser-triggered photothermal performance, which can be innovatively employed as sensitive photothermal agent for converting biological signals into temperature under the irradiation of NIR laser, accomplishing more simpler temperature quantitative detection by a portable thermometer. Furthermore, on account of the affinity discrepancy of MoS 2 NSs to single-stranded and double-stranded nucleic acids, a label-free proximity hybridization-based multifunctional assay platform was proposed for target detection with human epididymis-specific protein 4 (HE4) as model protein, demonstrating good analytical performances. Significantly, this innovative work not only enriches the foundational study of multi-model biosensing based on the unitary material but also provides an unambiguous guideline for exploring more accurate and simpler point-of-care diagnosis. Image 1 • A split-type multiple stimuli-responsive biosensor was outlined. • The MoS 2 -regulated split-type multi-signal readout format can be an essential stepping stone in the pursuit of simpler point-of-care diagnostics. • MoS 2 nanosheets not only acted as dual-promoter to improve the cathodic ECL, but used as nanozyme to regulate subsequent split-type visual colorimetric sensing. • This biosensor meets the demands of exactness and diversity in early clinical diagnosis. [ABSTRACT FROM AUTHOR]