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Thermal management of flexible/stretchable electronics has been a crucial issue. Mass supernumerary thermal heat is created in the repetitive course of deformation because of the large nanocontact resistance between electric conductive fillers, as well as the interfacial resistance between fillers and the polymer matrix. Here, we report a stretchable thermoplastic polyurethane (TPU)-boron nitride nanosheet (BNNS) composite film with a high in-plane thermal conductivity based on an air/water interfacial (AWI) assembly method. In addition to rigid devices, it was capable for thermal management of flexible electronics. During more than 2000 cycles of the bending-releasing process, the average saturated surface temperature of the flexible conductor covered with composite film with 30 wt % BNNSs was approximately 40.8 ± 1 °C (10.5 °C lower than that with pure TPU). Moreover, the thermal dissipating property of the composite under stretching was measured. All the results prove that this TPU-BNNS composite film is a candidate for thermal management of next-generation flexible/stretchable electronics with high power density.

To improve the efficiency of aptasensors, a signal amplification strategy by coupling tyrosinase (Tyr)-triggered redox cycling with nanoscale porous carbon (NCZIF) has been proposed. The NCZIF was obtained by calcining ZIF-8 crystals in an inert atmosphere. It had high surface areas, great biocompatibility, and ease of functionalization, which was beneficial for immobilizing sufficient Tyr and aptamer covalently. When the target prostate-specific antigen (PSA) was present, the NCZIF functionalized with Tyr and an aptamer bound to the aptamer-modified Au electrode specifically through the sandwich structure. Then, Tyr acted to oxidize the electroinactive phenol, which led to low-background signal, in the substrate to electroactive catechol, and triggered the redox cycling under the action of NADH. The low detection limit of the proposed electrochemical aptasensor for PSA was 0.01 ng mL-1, and the wide detection range was from 0.01 to 50 ng mL-1. The use of ZIF-8 derived porous carbon and Tyr-triggered redox cycling system provided a promising solution for the development of simple, rapid, reliable, and low-background aptasensing methods, which had great potential in the field of disease diagnosis and biomedicine.

The electrochemiluminescence (ECL) behavior of pyronin derivatives was reported. We found that these derivatives, as novel ECL emitters, generated an efficient emission phenomenon; that is, they showed anodic emission using tri-propylamine (TPA) as the coreactant and cathodic ECL emission using K2S2O8 as the coreactant. Because of its remarkable luminescent performance, the ECL mechanism (reductive-oxidative and oxidative-reductive) of benzylthiol-substituted pyronin (BTP) was specifically studied. Surprisingly, the cathodic ECL emission of BTP had a lower ECL peak potential at −0.54 V (vs. SCE) in aqueous solution. The potential range of −0.7 V to 0.0 V is lower than that of previously reported K2S2O8 cathodic ECL systems. Its good water solubility, easy modification, and excellent emission properties facilitate appealing (bio)analytical applications in ECL biosensors and cell imaging.

A novel electrochemical biosensor was constructed to detect p53 gene based on MIL-101-NH

A simple, low-cost, and universal gold nanoparticle (AuNP) aggregation-induced photothermal biosensing platform has been developed for the first time and applied for the visual quantitative genetic detection using a common thermometer. By exploiting the photothermal effect of target-induced gold nanoparticle aggregation, visual quantitative biochemical analysis can be achieved by simply recording temperature signals using a common thermometer. Compared to conventional genetic testing methods, it is label- and amplification-free and can be completed in 40 min without the aid of any advanced analytical instruments. Mycobacterium tuberculosis (MTB) DNA was used as a model target to demonstrate the application of this photothermal biosensing platform. Although no costly instrument was used, high sensitivity and specificity were achieved with the limit of detection (LOD) of 0.28 nM, which was nearly 10-fold lower than that of the colorimetric method using a spectrometer. This AuNP aggregation-induced photothermal biosensing strategy provides a simple, low-cost, and universal platform for broad application of visual quantitative detection of nucleic acids and many other biomolecules, particularly in point-of-care (POC) biosensing applications.

Nanozymes are a class of nanomaterials with enzyme-like activities that have been extensively studied for their possibilities and superiorities over natural enzymes. Intelligent design and fabrication of a nanozyme platform with highly efficient and stable tandem enzyme characteristics is necessary. Herein, a nanozyme cascade promoting bioplatform based on protein/bimetallic nanoparticles attached to ZIF-derived multilayer N-doped carbon nanosheets is proposed. Due to the carbon-based large surface area and solitary pairs of nitrogen electrons, the metal could be riveted to the carbon-based surface and reduced in situ to nanoparticles. Simultaneously, the addition of BSA has made it possible to establish a biological platform. The obtained BSA-PtAu@CNS has a linear range of 2 × 10

In this paper, novel synergetic PtNP@Co

In the study, a facile sonochemical method is described to fabricate a water-loving thermo- and redox- dual-sensitive micro-scale organogel (micro-organogel) as a drug carrier, where the drug-loaded organogel with the phase transition temperature of about 37 °C is encapsulated by the sulfydryl-crosslinked protein shell. Through the relevant characterization and measurement, the resultant micro-organogel has been found to be spherical and dispersed stably in an aqueous media, and its drug-loaded capacity is up to 86.05%. By the cytotoxicity assays, the micro-organogel has been proved to have a favorable biocompatibility, and the temperature-dependent and reductant-dependent release has demonstrated that the micro-organogel is a promising platform for the release-controlled drug delivery. In addition, the optimization of some experimental conditions has been also referred to obtain the small-sized micro-organogel, and the mean size of the final product is less than 600 nm with a narrow range.

An efficient colorimetric detection platform based on multi-enzyme cascade has been developed for detection of organophosphorus. Firstly, the dual-enzyme platform was prepared and applied for sensitive glucose detection (detection limit 0.32 μM). And then three enzymes, including acetylcholinesterase, horseradish peroxidase and choline oxidase were encapsulated in cruciate flower-like zeolitic imidazolate framework-8 (CF-ZIF-8) through one-step co-precipitation to construct detection platform with acetylcholine chloride as substrate. The acephate inhibited the activity of acetylcholinesterase, obstructed the cascade reaction and reduced the production of H

Sensitive detection of miRNA-21 provides remarkable results for the diagnosis of early breast cancer. Here, we fabricated a novel electrochemical biosensor for the ultrasensitive detection of miRNA-21 via in situ reduction of gold nanoparticles (AuNPs)-decorated Ti3C2 MXene, combined with a cascaded signal amplification strategy, that is, strand displacement of DNA walker-induced multi-DNA (product DNA) release and cyclic enzymatic signal amplification. First, in situ reduction of AuNPs on a Ti3C2 MXene layer was not only used as a carrier of capture DNA (C-DNA) and a way to make DNA hybridization accessible but also to provide a predominant (111) facet with high electrocatalytic activity of AuNPs that significantly ameliorated the electrochemical signal, in which MXene acted as both reductant and stabilizer. In addition, in the presence of miRNA-21, multi-DNA fragments (p-DNA) that were produced by strand displacement of the DNA walker could be captured by C-DNA on the fabricated biosensor and trigger Exo III cyclic digestion for further amplification of electrochemical signals. By cascaded signal amplification, the changes in peak signal currents (ΔI) using differential pulse voltammetry were amplified. Under optimal conditions, the electrochemical biosensor achieved a detection limit of 50 aM (S/N = 3) with a linear range from 100 aM to 1.0 nM. With its excellent analytical performance, this biosensor may have the potential to be used in early diagnosis and biomedical applications.

Graphical abstract, Highlights • The review offers an overview of the sonochemical synthesis of nano-scale inorganics. • The recent progress of sonochemistry in catalysis fields is discribled in the review. • Reduction, oxidation, degradation, polymerization or other catalysis are emphasized., Catalysis covers almost all the chemical reactions or processes aiming for many applications. Sonochemistry has emerged in designing and developing the synthesis of nano-structured materials, and the latest progress mainly focuses on the synthetic strategies, product properties as well as catalytic applications. This current review simply presents the sonochemical effects under ultrasound irradiation, roughly describes the ultrasound-synthesized inorganic nano-materials, and highlights the sonochemistry applications in the inorganics-based catalysis processes including reduction, oxidation, degradation, polymerization, etc. Or all in all, the review hopes to provide an integrated understanding of sonochemistry, emphasize the great significance of ultrasound-assisted synthesis in structured materials as a unique strategy, and broaden the updated applications of ultrasound irradiation in the catalysis fields.

Enzyme cascade reactions can greatly improve catalytic efficiency and achieve selective and sensitive detection of targets. This paper presents a novel strategy for colorimetric sensing of targets by loading natural enzymes into a hemin-doped G-quadruplex (G4-hemin) biohydrogel to form a flexible enzyme cascade sensing (FECS) platform. The biohydrogel has advantages of biocompatibility, printability and flexibility. The biohydrogel not only participates in the cascade reaction as the mimic enzyme but also provides a mild microenvironment for the natural enzyme. The FECS platform has a linear range from 0.4 μM to 120 μM and a detection limit of 3.6 × 10−6 M for hydrogen peroxide detection. Additionally, the FECS platform has a low detection limit and wide linear range for glucose and xanthine by loading xanthine oxidase (XOD) and glucose oxidase (GOD) into the biohydrogel, respectively. These results indicate that the novel FECS platform is an effective detection platform that can detect multiple targets and is expected to be widely used in flexible sensing.

As a class of crystalline porous materials, metal-organic frameworks (MOFs) have attracted increasing attention. Due to the nanoscale framework structure, adjustable pore size, large specific surface area, and good chemical stability, MOFs have been applied widely in many fields such as biosensors, biomedicine, electrocatalysis, energy storage and conversions. Especially when they are combined with aptamer functionalization, MOFs can be utilized to construct high-performance biosensors for numerous applications ranging from medical diagnostics and food safety inspection, to environmental surveillance. Herein, this article reviews recent innovations of aptamer-functionalized MOFs-based biosensors and their bio-applications. We first briefly introduce different functionalization methods of MOFs with aptamers, which provide a foundation for the construction of MOFs-based aptasensors. Then, we comprehensively summarize different types of MOFs-based aptasensors and their applications, in which MOFs serve as either signal probes or signal probe carriers for optical, electrochemical, and photoelectrochemical detection, with an emphasis on the former. Given recent substantial research interests in stimuli-responsive materials and the microfluidic lab-on-a-chip technology, we also present the stimuli-responsive aptamer-functionalized MOFs for sensing, followed by a brief overview on the integration of MOFs on microfluidic devices. Current limitations and prospective trends of MOFs-based biosensors are discussed at the end.

A simple homogeneous electrochemical aptasensor was designed by using target-responsive substrate releasing from aptamer-gated zeolitic imidazolate framework-8 (ZIF-8)-derived porous carbon nanocontainer. The nanocontainer (Z-700) was prepared by calcination of ZIF-8 at 700 °C. Z-700 had great biocompatibility, high surface areas and pore volume, especially the graphene-like π-rich structure, which was beneficial for adsorbing aptamer easily. The electroactive dyes methylene blue (MB) was then trapped in the pores of Z-700 and easily capped with aptamer as gatekeeper based on π-stacking interaction. Upon addition of target protein thrombin (Thb), the Thb could specifically recognize and combine with its aptamer to form complex. Thereafter, the aptamer bio-gate opened and the MB released from the pores, which could be detected on the screen-printed electrode. Under the optimized conditions, the proposed Thb aptasensor showed a wide detection range from 1 fM to 1 nM with a low detection limit of 0.57 fM. The strategy by using ZIF-8-derived porous carbon and aptamer bio-gate provides a promising scheme for developing simple, rapid, reliable and ultrasensitive bioassays, which has a great potential as a powerful tool in disease diagnosis and biomedicine.

In this protocol, a dual-channel homogeneous aptasenor was proposed for protein molecule determination, employing thrombin as target analyte. The colorimetric and electrochemical transducers were combined in a single analytical system for signal readout. In this dual-channel sensing strategy, the G-quadruplex sequence was released and incorporated with hemin to form DNAzyme for naked-eye colorimetric detection. Meanwhile, the hydroxyapatite nanoparticle as signal probe was combined with magnetic nanoparticles to construct sandwich-type structure for generating the electrochemical current when thrombin was present in solution. By introducing two kinds of reporter probes and transducers, this dual-channel sensor produced two different kinds of signal to improve the analytical accuracy and diversity. The results revealed that the dual-channel sensor achieved the quantatitive determination of thrombin with low limit of detection (0.40 fM) and wide range (0.1 fM to 1 nM), which offer a promise for rapid and accurate detection of biomolecule.

Herein, we report a high-performance electrocatalyst by orientationally growing Ni2P nanoparticles in situ on graphene film (Ni2P/G) for nonenzymatic glucose sensors in alkaline media. The combination of highly active Ni2P and stable graphene film with rapid conductivity enables this composite to display excellent electrochemical activity toward glucose with enhanced electron transfer rate and steadiness. With Ni-MOF-74 as a precursor, Ni2P/G showed even metal distribution, massive exposure of active sites, and spatially ordered structure. Benefiting from the synergistic reaction of Ni2P particles and graphene, this metal–organic frameworks (MOF)-derived composite exhibited high electrocatalytic activity and specificity toward glucose electrooxidation. Under optimized conditions, a wide linear response was obtained from 5 μM to 1.4 mM with a detection limit of 0.44 μM. Furthermore, an excellent linear response (R2 = 0.9897) was also obtained by a Ni2P/G modified electrode in human serum with the concentra...

A novel Nafion/polyaniline/Zeolitic Imidazolate Framework-8 nanocomposite (Nafion/PANI/ZIF-8) has been fabricated on the surface of glassy carbon electrode (GCE) for the electrochemical determination of dopamine (DA). In this sensor, ZIF-8 provides large surface area and excellent electrocatalytic activity while PANI exhibits great electric conductivity. Surface morphology and structure of the modified electrode were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The eletrocatalytic properties of the modified electrode were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The Nafion/PANI/ZIF-8 modified electrode displayed a high catalytic performance towards DA oxidation in PBS, which can be attributed to the synergistic effects of PANI and ZIF-8. Under the optimized conditions, the linear range was from 1.0 × 10−7 to 1.0 × 10−4 mol L−1 and the limit of detection was 1.2 × 10−8 mol L−1. In addition, the developed sensor showed great selectivity, high reproducibility, excellent stability and applicability in real samples analysis.

Highly dispersed ultrafine Pt nanoparticles (NPs) were loaded on a nickel-cobalt layered double hydroxide (NiCo-LDH) nanoarray that was grown on Ni foam (NF) via an in situ redox reaction without any external agent between Co2+ (Co(OH)2) in NiCo-LDH and PtCl62-. The obtained Pt/NiCo LDH/NF composite was used as a catalyst for methanol oxidation in alkaline media, showing much higher electrocatalytic activity and better anti-poisoning ability and stability for methanol oxidation than commercial Pt/C, mainly because of the uniform dispersion of ultrafine Pt NPs, the synergistic effect and stable support of NiCo LDH. The NiCo LDH nanoarray effectively increased the specific surface area and location sites for supporting Pt NPs and enhanced the catalytic performance and tolerance to intermediate species. This enhancement was probably due to the synergistic effect between Pt and the NiCo-LDH nanosheets, in which the LDH can provide adequate OH−ads species for accelerating the methanol oxidation reaction (MOR).

Herein, a sandwich-type homogeneous electrochemical aptasensor has been proposed for the determination of thrombin. The thrombin aptamer 1 modified magnetic nanoparticles (MNP-TBA1) are used as one recognition unit to bind the thrombin and the thrombin aptamer 2 modified hydroxyapatite nanoparticles (HAP-TBA2) are used as the other recognition unit for thrombin. When the thrombin exists, MNP-TBA1 is combined with HAP-TBA2 to form sandwich-type structure. In this protocol, HAP is also used as a signal probe, which can react with molybdate to produce redox-active molybdophosphate precipitates. In order to promote electron transfer and amplify signal, graphene is synthesized on the surface of electrode by one step. Compared with the traditional heterogeneous aptasensor, the homogeneous aptasensor can improve the target binding efficiency and avoid immobilizing biomolecule on the interface of electrode. Therefore, the homogeneous aptasensor presents a low detection limit of 0.03 fM for thrombin and a wide linear range (from 0.1 fM to 1.0 nM). Furthermore, the aptasensor exhibits a good selectivity and applicability in serum samples. More significantly, this homogeneous aptasensor gives inspiration to manufacture sensitive aptasensor for sensitive analysis of other biomarkers.

Reduced graphene oxide (RGO) has been shown to be an excellent support for Pt-based nanoparticles due to its large surface area and abundant chemical functional groups/defects available for anchoring. However, the restacking that occurs during the reduction of graphene oxide precludes its independent application. A variety of methods have been utilized to solve this problem, including surface modification, element doping, and insertion of separator. A novel NiFe layered double hydroxide/reduced graphene oxide (NiFe-LDH/RGO) composite was prepared by a facile one-pot solvothermal process using LDH as an effective separator, with subsequent Pt nanoparticles deposition via electrodeposition. The activity of this Pt/NiFe-LDH/RGO catalyst towards the methanol oxidation reaction (MOR) in alkaline media was studied by cyclic voltammetry (CV), and its stability was investigated by chronoamperometry (CA). The morphology was characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and scanning electron microscopy (SEM). The structure was determined by examining X-ray diffraction (XRD) patterns. The resulting Pt/Ni-Fe LDH/RGO electrocatalyst exhibits higher peak current density (949.3 mA mg−1), larger electrochemically active surface area (24.6 m2 g−1Pt) and better stability for methanol oxidation than its RGO-free counterpart (512.3 mA mg−1, 17.7 m2 g−1Pt). Moreover, the Pt nanoparticles mean diameter of Pt/NiFe-LDH/RGO electrocatalyst is 6.27 nm, which is much smaller than other contrast.

In this work, a new sensing scheme for protein detection is presented based on converting liquid-phase colorimetric assay into enhanced surface-tethered electrochemical analysis. In order to accomplish this conversion, we first design a colorimetric assay by using AuNPs-DNA sensing units and target-induced AuNPs-DNA sensing units, and then convert it into an electrochemical aptasensor for lysozyme detection by the same AuNPs-DNA sensing units and construction principle with the colorimetric assay. Compared with the colorimetric assay, the improved electrochemical aptasensor is more sensitive. Furthermore, it also has the superiority of simple principle and easy operation. This electrochemical aptasensor presents a low detection limit of 0:32 pM for lysozyme, wide linear range (from 1 pM to 10 nM), improved specificity and applicability in serum samples. More significantly, this sensing scheme gives inspiration to manufacturing sensitive and easily-operated electrochemical aptasensors adapted from colorimetric assay, which can satisfy the ambitious demands of sensitive analysis for biomarkers.

Abnormal levels of dopamine and uric acid are closely relative to some diseases of human body and can serve as key indicators for human health monitoring. As the primary products of purine metabolism, dopamine and uric acid generally coexist in the extracellular fluid of central nervous system and serum. The sensitive and simultaneous analysis of dopamine and uric acid is urgent in clinical diagnosis of some diseases. Herein, carboxylated-multiwall carbon nanotubes (MWCNTs) were functionalized with N-acetyl- l -cystein (NAC) stabilized Au clusters to generate Au@NAC- MWCNTs complex. By drop-coating the complex on glassy carbon electrode (GCE) surface, the complex-modified GCE was fabricated and used for a new working electrode for electrochemical sensing applications. Using cyclic voltammetry and differential pulse voltammetry measurements, the complex-modified GCE showed the capacity of highly sensitive, individual, and simultaneous electrochemical sensing of dopamine and uric acid. The linear detection ranges of dopamine and uric acid were 0.1–250 μM and 0.1–300 μM, respectively, accompanied by low detection limits of 30 nM of dopamine and 40 nM uric acid. In real human serum and urine samples, the complex- modified GCE exhibited a high performance for simultaneous and selective detection of dopamine and uric acid, together with high detection recoveries of 96.9–104.7% and low relative standard deviation of 1.1–3.7%.

In this paper, an exfoliated N-doped honeycomb cavernous carbon (ENC-800) with enhanced properties has been successfully synthesized by exfoliating carbonized metal-organic frameworks with high nitrogen content (N-MOFs) at liquid phase. Due to the high nitrogen content inheriting from the rich-imidazolyl organic ligand, ENC-800 shows excellent electrocatalytical activity and good performance as electrochemical detection platform. The substantial existence of graphitic N in ENC-800 provides generous C-N active site and high conductivity for catalyzing reaction. In addition, the increased specific surface area caused by exfoliation and evaporation of organic solvents confined in the N-MOFs also contributes to the electrochemical performance of ENC-800. In order to explore the potentiality of this material in electrochemical field, chloramphenicol (CAP) was detected by ENC-800 modified electrode and satisfactory results were obtained. In optimized conditions, the linear response of the ENC-800/GCE for CAP was obtained from 0.05 μM to 0.10 mM and from 0.10 mM to 3 mM with detection limit of 0.04 μM. Meanwhile, the new method to obtain an enhanced specific surface area by carbonizing solvent-contained MOFs provides a novel direction for post-processing of MOFs.

In this article, ternary nanocomposites consisting of silver nanoparticles (AgNPs), carbon dots (CDs) and reduced graphene oxide (rGO) were newly synthesized via a one-step electrodeposition method. Upon cyclic voltammetry (CV) scanning, ternary nanocomposites with dendritic structure were facilely generated and electrodeposited on glass carbon electrode (GCE), without involving toxic solvents and reducing agents. The nanocomposites were characterized by means of scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) techniques. Characterization results revealed that the nanocomposites showed dendritic structures and dispersible narrow-sized nanoparticles were deposited on the matrix of rGO, mainly attributed to the use of Ag(NH 3 ) 2 OH instead of Ag(NO 3 ) 2 as the precursor. The nanocomposites deposited on GCE had superior electrocatalytic activities for doxorubicin (DOX) reduction. The electrocatalytic activities were strongly affected by Ag(NH 3 ) 2 OH concentration. The best electrocatalytic activities could be obtained when the volume ratio of CDs-GO (3:1, v/v) to Ag(NH 3 ) 2 OH was fixed to 1:1. The peak current intensities of AgNPs-CDs-rGO/GCE sensing system linearly increased upon the increase of coexisting DOX concentration in the range from 1.0 × 10 −8 to 2.5 × 10 −6 M ( R 2 = 0.9956), together with a limit of detection as low as 2 nM.

A MOF-derived porous carbon with high specific surface area and robust structure was successfully synthesized by carbonizing zeolitic imidazolate framework (ZIF-8). With the investigation of the carbonization temperature and the preparation process, the synthesized ligand-derived carbon matrix (Z-1000) displayed a high electrical conductivity and electrochemical activity owing to the spatially ordered porous structure, high graphitization and doped nitrogen. In order to test the electrochemical properties of this material, a range of substances were detected by Z-1000 modified electrodes (Z-1000/GCE) and satisfactory results were obtained. In optimized conditions, the linear responses of the Z-1000/GCE for uric acid (UA) and catechol (CT) were obtained from 0.001 mM to 0.3 mM with detection limit of 1.4 × 10 −8 M and 2.78 × 10 −7 M, respectively. And a linear range for hydroquinone (HQ) was in the region of 0.001 mM–0.2 mM with detection limits of 2.15 × 10 −7 M. These unique physical and chemical properties made it hold great promise in the development of multifunctional sensor. Meanwhile, the low cost and facile preparation of MOF-derived carbon made it become a potential candidate for electroanalysis.

The PtCo-graphene/carbon dots/graphene (PtCo/GCG) electrocatalyst was prepared on a glassy carbon electrode via electrodeposition of PtCo nanoparticles onto the sandwich-structured graphene/carbon dots/graphene (GCG) composite. The obtained PtCo/GCG electrocatalyst has been characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and also electrochemical measurements. Structure characterization indicates that the PtCo/GCG catalyst has good layered graphene morphology, with PtCo nanoparticles uniformly dispersed between the graphene layers. Electrochemical results indicate that PtCo/GCG catalyst has much better electrocatalytic activity and stability toward methanol oxidation when compared with PtCo/graphene and Pt catalysts. The improved performance is mainly owing to the embedding of carbon dots into the graphene layers, and the synergistic effect between Pt and Co nanoparticles. Carbon dots effectively adsorbed onto graphene layers, which increase the electrical conductivity, enhance the dispersion of PtCo nanoparticles, and subsequently enlarge the reactive surface area with more active sites.