Search

[Display omitted] Novel two-dimensional MXene with unique optical and electrical properties has become a new focus in the field of sensing. In particular, their metallic conductivity, good biocompatibility and high anchoring ability to biomaterials make them attractive candidates. Despite such remarkable properties, there are certain limitations, such as low oxidative stability. MXene-Metal interactions are an effective strategy to maintain the long-term stability of MXene, while also improving the electrochemical activity and optical properties. Herein, a series of MXene/Ag nanocomposites including Ti 3 C 2 /Ag, Nb 2 C/Ag and V 2 C/Ag were designed based on the surface chemistry characteristics of MXene, where MXene served as the substrate for in-situ growth of silver nanoparticles via self-reduction of Ag(NH 3) 2 +. The results showed that V 2 C MXene has the strongest self-reducing ability due to its multiple variable valence states, larger interlayer space and more reactive groups. Moreover, V 2 C/Ag exhibited unexpected oxygen reduction reaction catalytic activity and photothermal performance. In view of which, an electrochemiluminescence-photothermal (ECL-photothermal) immunosensor was developed using V 2 C/Ag as ECL anchor and photothermal reagent for ultrasensitive detection of Lipolysis stimulated lipoprotein receptor. This work not only provides a simple and effective synthesis method of MXene supported metal nanocomposites, but also provides more inspirations for exploring the efficient biosensing strategies. [ABSTRACT FROM AUTHOR]

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]

Exploring the photochemical (PEC) method induced by low-energy light source makes great significance to achieve high stability and accurate analysis. A sensing platform driven by near-infrared (NIR) light was designed by making the biochemically encoded carbon rich plasmonic hybrid (CPH) probe, the peptide@C–Mo 2 C. The inherent plasmonic effect of C–Mo 2 C CPH can directly absorb NIR light, thus starting effective electronic-hole pairs separation. Moreover, the photothermal effect of C–Mo 2 C CPH also promoted the reaction yield of photothermal catalyst reaction on sensing interface to assist the PEC signal amplification. In the presence of target trypsin, it cleaves the peptides, resulting in the release of peptide@C–Mo 2 C probe from interface, which leads to a relative decrease in PEC signal. More importantly, a self-calibration system consisting of two independent PEC test channels attempted to eliminate the influence of background signal and baseline drift. The test channel was used to specify the recognition target, while the blank channel was used as a reference. Therefore, the signal difference between two channels was recorded, so as to obtain results with less error and higher stability. In this NIR driven PEC sensor, the carbon rich probe with direct and efficient NIR light conversion promoted the sensitivity and a self-calibration system guaranteed the stability which provided innovative thoughts for developing ingenious PEC sensor. [ABSTRACT FROM AUTHOR]

Utilizing the photothermal effect to activate enzyme activity, realize signal conversion and amplification show promising prospects in biosensing. Herein, a pressure-colorimetric multi-mode bio-sensor was proposed through the multiple rolling signal amplification strategy of photothermal control. Under NIR light radiation, the Nb 2 C MXene labeled photothermal probe caused notable temperature elevation on a multi-functional signal conversion paper (MSCP), leading to decomposition of thermal responsive element and in-situ formation of Nb 2 C MXene/Ag-S x hybrid. The generation of Nb 2 C MXene/Ag-S x hybrid accompanied with valid color change from pale yellow to dark brown on MSCP. Moreover, the Ag-S x as a signal amplification element enhanced the NIR light absorption to further improve the photothermal effect of Nb 2 C MXene/Ag-S x thereby induce cyclic in situ production of Nb 2 C MXene/Ag-S x hybrid with rolling enhanced photothermal effect. Subsequently, the continuously enhanced photothermal effect rolling activated catalase-like activity of Nb 2 C MXene/Ag-S x , which accelerated the decomposition of H 2 O 2 and promoted the pressure elevation. Therefore, the rolling-enhanced photothermal effect and rolling activated catalase-like activity of Nb 2 C MXene/Ag-S x considerately amplified the pressure and color change. Making full use of multi-signal readout conversion and rolling signal amplification, accurate results can be obtained in a short time, whether in the laboratory or in the patient ' s homes. [Display omitted] • A pressure-colorimetric system relied on photothermal activated multiple rolling signal amplification was established. • The photothermal probe drove thermal responsive element decomposition and in-situ generation of Ag-S x on MSCP. • The Ag-S x induced cyclic production of Nb 2 C MXene/Ag-Sx hybrid with rolling enhanced photothermal effect. • The rolling-enhanced photothermal effect activated the catalase-like of Nb 2 C MXene/Ag-S x to amplify the pressure signal. [ABSTRACT FROM AUTHOR]

Herein, an ingenious dual-readout sensing platform based on a proximity hybridization-regulated strategy is proposed for protein detection. For the first time, Ti3C2 MXene@thionine composites (MXene@Thi) with an excellent photothermal effect not only acted as an amplifier to enhance the electrochemical signal, but were also used as a converter to achieve the temperature readout. [ABSTRACT FROM AUTHOR]

[Display omitted] • A multiple sensitization ECL system was constructed using a synergistic photothermal amplification strategy. • Tetraethylene pentamine was first reported as a coreactant reagent for Ru bpy 3 2 + . • Nanomaterial-anchored Ru bpy 3 2 + and TEPA as the self-enhanced signal probe. A synergistic amplified electrochemiluminescent (ECL) immunoassay was constructed by utilizing an efficiently self-enhanced signal tag and sensing substrate with satisfactory photothermal property for thyroglobulin ultrasensitive detection. Concretely, tetraethylene pentamine (TEPA) was first attempted for the coreactant of Ru bpy 3 2 + , and mesoporous silica nanostars with large surface area and porous structure was designed as a support material to integrate Ru bpy 3 2 + and TEPA, forming a self-enhanced signal tag to improve ECL efficiency. Additionally, magnetic beads with excellent photothermal effect was used as ideal sensing substrate to obtain the further amplified ECL signal because of the accelerated electron diffusion and reaction process induced by increased electrode temperature under the near-infrared laser irradiation. With the self-enhanced and photothermal synergistic amplified strategy, the proposed ECL sensor showed a wide linear range from 10−5 to 10 ng/mL with a low detection limit of 3.3 × 10−6 ng/mL. This work will provide a promising avenue to simplify the synthesis of self-enhanced ECL emitter complexes, and pave the avenue for achieving synergistic enhancement of ECL signals by incorporating probe substrates. [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]

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]

• 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]