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When an acute myocardial infarction (AMI) occurs, myoglobin (Mb) is the biomarker whose concentration firstly increases, and the high sensitive detection of Mb is critical for early diagnosis of AMI. Herein, a sandwich-type electrochemical aptasensor for the sensitive detection of Mb was constructed by using Pt@Cu 1.33 OCo 0.83 O as the signal marker. On one hand, nano-flower-like Cu 1.33 OCo 0.83 O was synthesized by hydrothermal method and Pt nanoparticles (Pt NPs) were loaded on its surface. Pt@Cu 1.33 OCo 0.83 O could immobilize aptamer 2 (Apt2) successfully by the Pt-S bond. And because of the synergistic effect between Pt and bimetallic oxide, Pt@Cu 1.33 OCo 0.83 O had an excellent catalytic effect on the signal source of hydrogen peroxide (H 2 O 2 ) to amplify the current signal, which enhance the sensitivity of the aptasensor. On the other hand, the screen-printed gold electrode (SPGE) was used as the sensing base, which had good conductivity and ensured the immobilization of aptamer 1 (Apt1). The quantitative detection of Mb was achieved by specific recognition between Mb and Apt1, Apt2. As a result, the constructed electrochemical aptasensor had a good linear range (1-1500 ng/mL) with a low detection limit (LOD) of 0.128 ng/mL (S/N = 3), and a high sensitivity of 29.47 μA dec -1 . The aptasensor also realized the detection of Mb in human serum samples with good accuracy, and the results were consistent with the hospital's biochemical indicators, which demonstrated the potential application of the prepared sensor in the clinical detection of Mb., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Quantifying multiple biomarkers with high sensitivity in tiny biological samples is essential to meet the growing demand for point-of-care testing. This paper reports the development of a novel microfluidic device integrated with mass-producible micropillar array electrodes (μAEs) for multiple biomarker detections. The μAE are mass-fabricated by soft lithography and hot embossing technique. Pt-Pd bimetallic nanoclusters (BNC) are modified on the surface of μAEs by constant potential (CP)/multi-potential step (MPS) electrodeposition strategies to improve the electroanalytical performance. The experimental result displays that Pt-Pd BNC/μAEs have good sensitivity enhancement compared with bare planar electrodes and bare μAEs, the enhancement being 56.5 and 9.5 times respectively, from the results of the H 2 O 2 detection. Furthermore, glucose, uric acid and sarcosine were used as model biomarkers to show the biosensing capability with high sensitivity. The linear range and LOD of the glucose, uric acid and sarcosine detection are 0.1 mM-12 mM, 10 μM-800 μM and 2.5 μM-100 μM, 58.5, 3.4 and 0.4 μM, respectively. In particular, biosensing chips show wide linear ranges covering required detection ranges of glucose, uric acid and sarcosine in human serum, indicating the developed device has great potential in self-health management and clinical requirements., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Adenosine, as an endogenous nucleoside modulator, plays an important role in heart rate regulation, neurotransmission, and control of the respiratory system and thus it is significantly important to realize its sensitive detection. Herein, a highly sensitive electrochemical aptasensor for adenosine detection was proposed by using multi-walled carbon nanotubes (MWCNTs) as support matrix loading PtCu nanoparticles (PtCu-MWCNTs) to amplify signal. On one hand, disposable screen-printing gold electrodes (SPGEs) were used as superb sensing base to ensure the stable connection of aptamers 1 (ssDNA1). On the other hand, the PtCu-MWCNTs complex was synthesized through a one-pot method, which not only can precisely control the proportion of metal mass in the product but also exhibited superior electrocatalytic activity towards H 2 O 2 . The recognition reactions were achieved by stepwise incubation of ssDNA1, ssDNA2-PtCu-MWCNTs (denoted as ssDNA2-label), and adenosine on the SPGEs. As a result, the constructed electrochemical aptasensor exhibited a wide linear range from 10 nM to 1.0 μM with a low detection limit of 1.0 nM (S/N = 3) for adenosine detection. The aptasensor also successfully realized the adenosine detection in human serum samples, which means that the proposed aptasensor holds a potential application in point-of-care detection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Quantifying biomarkers at the early stage of the disease is challenging due to the low abundance of biomarkers in the sample and the lack of sensitive techniques. This article reports the development of a novel microfluidic electrochemical biosensing platform to address this challenge. The electrochemical sensing is achieved by utilizing a micropillar array electrode (μAE) coated with 3D bimetallic Pt-Pd nanotrees to enhance the sensitivity. A bubble-based acoustic microstreaming technique is integrated with the device to increase the contact of analyte molecules with the surface of electrodes to further enhance the electrochemical performance. The current density of Pt-Pd NTs/μAE with acoustic microstreaming is nearly 22 times that of the bare planar electrode in potassium ferrocyanide solution. The developed biosensor has demonstrated excellent sensing performance. For hydrogen peroxide detection, both the Pt-Pd NTs/μAE and acoustic microstreaming contribute to the sensitivity enhancement. The current density of the Pt-Pd NTs/μAE is approximatively 28 times that of the bare μAE. With acoustic microstreaming, this enhancement is further increased by nearly 1.6 times. The platform has a linear detection range of 5-1000 μM with a LOD of 1.8 μM toward hydrogen peroxide detection, while for sarcosine detection, the linear range is between 5 and 100 μM and LOD is 2.2 μM, respectively. Furthermore, the sarcosine biosensing shows a high sensitivity of 667 μA mM -1 ∙cm -2 . Such a sensing platform has the potential as a portable device for high sensitivity detection of biomarkers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

The detection of cancer biomarkers is of great significance for the early screening of cancer. Detecting the content of sarcosine in blood or urine has been considered to provide a basis for the diagnosis of prostate cancer. However, it still lacks simple, high-precision and wide-ranging sarcosine detection methods. In this work, a Ti 3 C 2 T X /Pt-Pd nanocomposite with high stability and excellent electrochemical performance has been synthesized by a facile one-step alcohol reduction and then used on a glassy carbon electrode (GCE) with sarcosine oxidase (SO x ) to form a sarcosine biosensor (GCE/Ti 3 C 2 T X /Pt-Pd/SO x ). The prominent electrocatalytic activity and biocompatibility of Ti 3 C 2 T X /Pt-Pd enable the SO x to be highly active and sensitive to sarcosine. Under the optimized conditions, the prepared biosensor has a wide linear detection range to sarcosine from 1 to 1000 µM with a low limit of detection of 0.16 µM (S/N = 3) and a sensitivity of 84.1 µA/mM cm 2 . Besides, the reliable response in serum samples shows its potential in the early diagnosis of prostate cancer. More importantly, the successful construction and application of the amperometric biosensor based on Ti 3 C 2 T X /Pt-Pd will provide a meaningful reference for detecting other cancer biomarkers., (© 2022 Wiley-VCH GmbH.)

The cardiac troponin I (cTnI) detection is increasingly significant given its promising value in the clinical acute myocardial infarction diagnosis. Here a sensitive sandwich-type cTnI electrochemical aptasensor was developed by using zirconium-carbon loaded with Au (Au/Zr-C) as electrode-modified material and snowflake-like PtCuNi catalyst as label material. The Au/Zr-C was prepared from a carbonation process and a reduction step. The PtCuNi was synthesized by a one-pot hydrothermal reaction. On the one hand, due to its many merits of large effective area, rich pores, high degree of graphitization, the assistance of Au, the Au/Zr-C exhibited remarkable electronic conductivity but low catalytical capacity, thus improving the electrochemical property but lowing the background signal of electrode. On the other hand, because of its accessible active sites of the special snowflake-like structure and the synergy of three elements, the PtCuNi catalyst presented excellent catalytic activity and improved stability compared to binary alloy. The recognition reactions were achieved by stepwise incubation of aptamer 1, cTnI, and aptamer 2-PtCuNi (denoted as Apt2-label) on the Au/Zr-C-modified electrode. The electrocatalytic signals of the immobilized Apt2-label towards the H 2 O 2 reduction were recorded in all tests for cTnI analysis. Consequently, this cTnI aptasensor exhibited excellent performance involving a wide linear range of 100 ng mL -1 to 0.01 pg mL -1 with a detection limit of 1.24 × 10 -3  pg mL -1 (S/N = 3), good selectivity, satisfying reproducibility, outstanding stability, and good recovery., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Two-dimensional (2D) porous carbon-based composite nanosheets loaded with metal oxide nanoclusters are expected to be promising electrocatalysts for high-performance electrochemical sensors. However, for this complicated composite material, strict reaction conditions and complex synthesis steps limit its general application in electrochemical detection. Here we present a facile method to fabricate 2D mesoporous nitrogen-rich carbon nanosheets loaded with CeO 2 nanoclusters (2D-mNC@CeO 2 ), for fabricating superoxide anions (O 2 •- ) electrochemical sensor. The method is based on block copolymers self-assembly and the affinity of polydopamine to metal ions to obtain organic-inorganic hybrid, which can be directly converted into 2D-mNC@CeO 2 through carbonization strategy without structural deterioration. Characterizations demonstrate that the 2D-mNC@CeO 2 owned the 2D N-doped carbon structure with an interlinked hierarchical mesoporous and the uniformly dispersed CeO 2 nanoclusters on the surface. Benefitted from the unique structure, the 2D-mNC@CeO 2 shortens electron transfer distance, enhances mass transfer efficiency, exposes numerous active sites, and obtain a high Ce 3+ /Ce 4+ ratio for improving electrocatalytic performance. The 2D-mNC@CeO 2 /SPCEs sensors for O 2 •- detection has a detection limit of 0.179 μM (S/N = 3) and sensitivity of 401.4 μA cm -2 mM -1 . The sensors can be applied to capture electrochemical signals of O 2 •- released from HepG2 cells, demonstrating the application potential of the sensors to monitor O 2 •- in biological fields., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Signal amplification is crucial to improve the sensitivity for the electrochemical detection of cardiac troponin I (cTnI), one of the ideal biomarkers for early acute myocardial infarction (AMI) diagnosis. Herein, we developed a novel signal amplification strategy to construct a sandwich-type electrochemical aptasensor for the detection of cTnI. Core-shell Pd@Pt dendritic bimetallic nanoparticles loaded on melamine modified hollow mesoporous carbon spheres (Pd@Pt DNs/NH 2 -HMCS) was prepared as labels to conjugate with thiol-modification DNA aptamers probe for signal amplification. While introducing numerous amino groups, the melamine functionalized hollow mesoporous carbon spheres (NH 2 -HMCS) retained the edge-plane-like defective sites for the adhesion and electrocatalytic reduction of H 2 O 2 . With the unique characteristics of NH 2 -HMCS, it not only enhanced the dispersity and loading capacity of core-shell Pd@Pt dendritic bimetallic nanoparticles (Pd@Pt DNs), but also improved the stability of bonding by the affinity interaction between Pd@Pt DNs and amino groups of melamine. Meanwhile, the synergistic catalysis effect between Pd@Pt DNs and NH 2 -HMCS significantly enhanced the electrocatalytic reduction of H 2 O 2 and further amplified the signal. Under optimal conditions, this recommended aptasensor for cTnI detection displayed a wide dynamic range from 0.1 pg/mL to 100.0 ng/mL and a low detection limit of 15.4 fg/mL (S/N = 3). The sensor also successfully realized the analysis of cTnI-spiked human serum samples, meaning potential applications in AMI diagnosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The detection of circulating tumor DNA (ctDNA) has increasingly received a great deal of attention considering its significance in cancer diagnosis. And the signal amplification plays an important role in the development of sensitive ctDNA biosensors. Herein, the nanocomposites (denoted as HAC-AuPt), integrating from high-active carbon (HAC) and AuPt alloy nanoparticles, were synthesized and subsequently used as a signal amplification label to fabricate a sandwich-type ctDNA electrochemical biosensor. Characterizations demonstrated that HAC presents uniform size distribution and AuPt alloy nanoparticles were successfully loaded on HAC. The current response could be amplified to a great extent by the resultant HAC-AuPt due to its excellent electrochemical property. The nanocomposites were further bounded with DNA signal probes (SPs) via Au-S or Pt-S assembly to form SPs-label. After the capture probes (CPs) were immobilized on the electrode surface, the target DNA (tDNA) and SPs-label were stepwise incubated on the CPs-modified electrode, thus forming a sandwich-type structure. By monitoring the catalytic signal of HAC-AuPt towards the reduction process of H 2 O 2 , this biosensor provided a wide linear range of 10 -8  mol/L - 10 -16  mol/L with a low detection limit of 3.6 × 10 -17  mol/L (S/N = 3) for the detection of the tDNA. Furthermore, obvious differences in response signals among different DNAs were observed benefitting from the excellent selectivity of the biosensor. Besides, the long-term stability, reproducibility, and recovery rate were proved to be outstanding. These results indicate that the established biosensor holds a potential application in the clinical diagnosis of ctDNA., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Here we presented a new facile strategy to fabricate ultrathin two-dimensional (2D) metal oxide nanosheets, by using polydopamine-coated graphene (rGO@PDA) as a template under simply wet-chemical conditions. Based on the strategy, graphene-like CeO 2 -TiO 2 mesoporous nanosheet (MNS-CeO 2 -TiO 2 ) was prepared and was loaded with dispersive Ag nanoparticles (AgNPs) to obtain effective electrocatalysts (denoted as Ag/MNS-CeO 2 -TiO 2 ) for electrochemical detection of superoxide anion (O 2 •- ). Characterizations demonstrated that MNS-CeO 2 -TiO 2 exhibited ultrathin thickness, larger specific surface area, and pore volume in comparison with its bulk counterpart. The above properties of MNS-CeO 2 -TiO 2 shorten electron transmission distance, promotes mass transfer, and is conducive to the dispersion of post-modified AgNPs. Therefore, the recommended Ag/MNS-CeO 2 -TiO 2 sensors (denoted as Ag/MNS-CeO 2 -TiO 2 /SPCE) exhibited satisfactory properties, including the sensitivity of 737.1 μA cm -2 mM -1 , the detection limit of 0.0879 μM (S/N = 3), and good selectivity. Meanwhile, the sensors also successfully realized in the online monitoring of O 2 •- released from HepG2 cells, meaning the prepared sensors had practical application potential towards the analysis of O 2 •- in biological samples., (Copyright © 2021 Elsevier B.V. All rights reserved.)

An enzyme-free, metal-free, and preconcentration-free electrochemical sensor for pentachlorophenol assay has been fabricated. The interface of the sensor is based on a hollow zeolitic imidazolate framework-derived mesoporous carbon material (denoted as HZC/SPCE). The sensor exhibits linear amperometric response upon pentachlorophenol at 0.82 V (vs. Ag/AgCl) in the concentration range 0.001 to 26.8 mg L -1 (3.75 × 10 -8 ~1.006 × 10 -4  M) (R 2  = 0.997). The sensitivity of HZC/SPCE is 3.53 × 10 2  μA mM -1  cm -2 with a detection limit of 2.05 × 10 -9  M (S/N = 3) for pentachlorophenol. The method has been applied to the determination of pentachlorophenol in spiked food packaging samples with recoveries in the range 92.0 to 107.0%. Graphical abstract Schematic representation of the synthesis of hollow ZIFs-derived hollow carbon material. Free protons derived from tannic acid penetrated into ZIF-8 to destroy its solid framework and the outer parts covered by tannic acid were protected from further etching. After pyrolysis, the morphology of HZC remained similar to that of HZIF-8. Abbreviation: CTAB: hexadecyl trimethyl ammonium bromide; Melm: 2-methylimidazole; ZIF-8: zeolitic imidazolate framework-8; TA: tannic acid; HZIF-8: hollow zeolitic imidazolate framework-8; HZC: hollow zeolitic imidazolate frameworks (ZIFs)-derived mesoporous carbon material.

Here we present a new method to fabricate enzyme-mimic metal-free catalysts for electrochemical detection of superoxide anion (O 2 •- ) by introducing phosphate groups into graphene-based foam. Through a template-free hydrothermal process, graphene oxide (GO) was treated with different amount of phytic acid (PA) to obtain 3D porous graphene-based foam (PAGF). Characterizations demonstrate that phosphate groups were successfully modified on the surface and inter layer structure of PAGF materials and the defects and disorder degree of PAGF could be controlled by adjusting the addition of PA precursors. Meanwhile, the synthesized PAGF was successfully immobilized on screen printed carbon electrodes (SPCEs) and employed in O 2 •- detection. With PA treated on graphene structure, the resulted PAGF/SPCEs exhibit distinct characteristic redox peaks, showing enzyme-mimic catalytic activity toward O 2 •- dismutation. Also, the amount of modified phosphate groups has caused a considerable variety on the performance of PAGF-based electrodes. Apart from high sensitivity, wide liner range, low detection limit, good selectivity and long-term stability, our sensors also present satisfying performance in the real-time monitoring of drug-induced O 2 •- released from Hela cells. The reliability of the biological measurement was further demonstrated via electron paramagnetic resonance (EPR) to characterize the released O 2 •- from stimulated cells by using 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) to trap the transient O 2 •- . The above results indicate that our established sensors hold potential application in the real-time detection of O 2 •- in biological samples., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Surface charge engineering of nanosized CuS via acidic amino acid modification is proved to be an efficient strategy to realize high peroxidase-mimicking catalytic activity at neutral pH. As a proof-of-concept application, one-pot high-performance colorimetric sensing of glucose by coupling the engineered nanozyme with glucose oxidase is realized.

Quantification of superoxide anions (O 2 •- ) is significant in the monitoring of many serious diseases and the design of enzyme-mimic catalysts plays the main role in the development of non-enzymatic O 2 •- sensors. Herein, we proposed a facile self-assembly process to synthesize manganese phosphate modified carbon networks using three kinds of widely-used carbon materials (MWCNTs, NGS and GO) as pillar connectors. Characterizations demonstrate that manganese phosphate is widely dispersed inside and on the surface of carbon networks without visible morphology. Meanwhile, all three kinds of synthesized catalysts were successfully immobilized on the screen-printed carbon electrodes to evaluate the electrochemical performance of fabricated sensors. The results indicate that sensors based on Mn x (PO 4 ) y modified MWCNTs exhibit high sensitivity with an extremely low detection limit of 0.127μM (S/N = 3) and a wide liner range of 0-1.817mM (R 2 = 0.998). We further employed the recommended sensors in the real-time monitoring of HepG2 cells released O 2 •- under the stimulating of Zymosan (20mg/mL). Noticeably, the proposed sensors exhibit not only sensitive response but also stable current steps upon different addition of Zymosan. The calculated concentrations of cell-released O 2 •- vary from 6.772 to 24.652pM cell -1 for the Zymosan amount used in this work. The established novel sensors display low background current and signal noises, thus holding unique advantages in the trace analysis of O 2 •- in biological samples and in vivo environment., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Nanosized materials acting as substitutes of natural enzymes are currently attracting significant research due to their stable enzyme-like characteristics, but some flaws of these nanozymes, including their limited catalytic rate and efficiency, need to be remedied to enable their wider applications. In this work, we verify for the first time the catalytic behavior of uncapped nanobranch-based CuS clews as a peroxidase mimic. XRD, XPS, SEM, and TEM proofs demonstrate that high-purity CuS clews composed of intertwined wires with abundant nanodendrites outside are successfully produced via a facile one-pot hydrothermal synthesis approach, with thiourea as both the sulfion source and the structure-directing agent. The synthesized CuS can catalytically oxidize 3,3',5,5'-tetramethylbenzidine (TMB) by H 2 O 2 to trigger a visible color reaction with rapid response (reaching a maximum change within 5 min). The proposed CuS nanozyme exhibits preferable catalytic kinetics over natural horseradish peroxidase (HRP). This outstanding activity primarily results from the large surface area and rich sites exposed by the uncapped unique structure. Under optimized conditions, the fabricated sensing system provides linear absorbance (652 nm) changes in the H 2 O 2 concentration range of 0.2˜130 μM, with a detection limit of as low as 63 nM. When coupled with glucose oxidase (GOD), the system is demonstrated to be capable of monitoring glucose in blood samples with excellent performance., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Considering the critical roles of superoxide anion (O2(∙-)) in pathological conditions, it is of great urgency to establish a reliable and durable approach for real-time determination of O2(∙-). In this study, we propose a porous Pt-Pd decorated superoxide dismutase (SOD) sensor for qualitative and quantitative detection O2(∙-). The developed biosensor exhibits a fast, selective and linear amperometric response upon O2(∙-) in the concentration scope of 16 to 1,536 μM (R(2)=0.9941), with a detection limit of 0.13 μM (S/N=3) and a low Michaelis-Menten constant of 1.37 μM which indicating a high enzymatic activity and affinity to O2(∙-). Inspiringly, the proposed sensor possesses an ultrahigh sensitivity of 1270 μA mM(-1)cm(-2). In addition, SOD/porous Pt-Pd sensor exhibits excellent anti-interference property, reproducibility and long-term storage stability. Beyond our expectation, the trace level of O2(∙-) released from living cells has also been successfully captured. These satisfactory results are mainly ascribed to (1) the porous interface with larger surface area and more active sites to provide a biocompatible environment for SOD (2) the specific biocatalysis of SOD towards O2(∙-) and (3) porous Pt-Pd nanomaterials fastening the electron transfer. The superior electrochemical performance makes SOD/porous Pt-Pd sensor a promising candidate for monitoring the dynamic changes of O2(∙-)in vivo., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Monitoring of reactive oxygen species like superoxide anion (O2(∙-)) turns to be of increasing significance considering their potential damages to organism. In the present work, we fabricated a novel O2(∙-) electrochemical sensor through immobilizing superoxide dismutase (SOD) onto a Pt-Pd/MWCNTs hybrid modified electrode surface. The Pt-Pd/MWCNTs hybrid was synthesized via a facile one-step alcohol-reduction process, and well characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The immobilization of SOD was accomplished using a simple drop-casting method, and the performance of the assembled enzyme-based sensor for O2(∙-) detection was systematically investigated by several electrochemcial techniques. Thanks to the specific biocatalysis of SOD towards O2(∙-) and the Pt-Pd/MWCNTs - promoted fast electron transfer at the fabricated interface, the developed biosensor exhibits a fast, selective and linear amperometric response upon O2(∙-) in the concentration scope of 40-1550 μM (R(2)=0.9941), with a sensitivity of 0.601 mA cm(-2) mM(-1) and a detection limit of 0.71 μM (S/N=3). In addition, the favorable biocompatibility of this electrode interface endows the prepared biosensor with excellent long-term stability (a sensitivity loss of only 3% over a period of 30 days). It is promising that the proposed sensor will be utilized as an effective tool to quantitatively monitor the dynamic changes of O2(∙-) in biological systems., (Copyright © 2014 Elsevier B.V. All rights reserved.)

In the present work, a high-performance enzyme-based electrochemical sensor for the detection of superoxide anion radical (O2(●-)) is reported. Firstly, we employed a facile approach to synthesize PtPd nanoparticles (PtPd NPs) on chemically reduced graphene oxide (RGO) coated with polydopamine (PDA). The prepared PtPd-PDARGO composite was well characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectra, X-ray diffraction, X-ray photoelectron spectroscopy and electrochemical methods. Then the assembled composite was used as a desired electrochemcial interface for superoxide dismutase (SOD) immobilization. Owing to the PDA layer as well as the synergistic effect of PtPd NPs, the fabricated SOD/PtPd-PDARGO sensor exhibited an outstanding sensitivity of 909.7 μA mM(-1) cm(-2) upon O2(●-) in a linear range from 0.016 mM to 0.24 mM (R(2)=0.992), with a low detection limit of 2 μM (S/N=3) and excellent selectivity, good reproducibility as well as favorable long-term stability., (Copyright © 2015 Elsevier B.V. All rights reserved.)

It is widely thought in electro-biochemical analysis that the sensing interfaces play a key role in the enzymeless detection of biomolecules like glucose, ascorbic acid, dopamine and uric acid. On the way to maximize the anti-poisoning sensitivity of nonenzymatic electrochemical glucose sensors as well as achieve favorable selectivity, we propose here a porous interface fabricated by a facile but effective approach for glucose monitoring in alkaline media containing dissolved oxygen. The sensing interface based on porous Cu foams is directly formed on a homemade disposable screen-printed carbon electrode (SPCE) substrate by electrodeposition assisted with hydrogen evolution simultaneously, and its porosity can be easily tailored through adjusting deposition conditions for the optimal electrocatalytic oxidation of glucose molecules. SEM and BET studies show that the generated Cu foam possesses robust hierarchical porous architectures with greatly enhanced surface area and pore volume, beneficial for the unimpeded mobility of glucose and reaction products. Cyclic voltammetric tests indicate that a diffusion-controlled glucose electro-oxidation reaction occurs at the Cu foam electrode at around +0.35 V vs. Ag/AgCl in 0.1 M NaOH. Chronoamperometric results obtained under optimized conditions reveal that the proposed sensor exhibits desired poison resistance ability in the presence of chloride ions and significant selectivity to glucose, providing fascinating sensitivities of 2.57 and 1.81 mA cm(-2) mM(-1) for glucose in the linear concentration ranges of 2-80 μM and 0.1-5 mM, respectively. The limit of detection is calculated to be as low as 0.98 μM according to the signal-to-noise ratio of three. In addition, the fabricated sensing interface shows attractive reproducibility (RSD of 5.1% and 7.0% for 15 repeated measurements on a sensor and for measurements on 15 prepared sensors, respectively) and outstanding long-term stability (less than 5% loss in sensitivity over 1 month) for glucose detection. The application of the Cu foam based sensor for monitoring glucose in practical samples is also successfully demonstrated., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Novel snowflake-like Pt-Pd bimetallic nanoclusters (Pt-PdBNC) were synthesized on a screen-printed gold nanofilm electrode (SPGFE) substrate by electrochemically reducing precursors with a new constant potential/multi-potential step deposition strategy. The electrocatalytic behavior of the modified electrode (SPGFE/Pt-PdBNC) towards H(2)O(2) was investigated. The results indicate that the as-prepared Pt-PdBNC significantly enhances the electrochemical reduction of H(2)O(2) in neutral media, exhibiting preferable electrocatalytic performance compared to Pt and Pd monometallic nanoclusters. Under optimum conditions, SPGFE/Pt-PdBNC offers linear responses for H(2)O(2) in the concentration range from 0.005 to 6 mM with an ultrahigh sensitivity of 804 mA M(-1) cm(-2) and excellent selectivity. Furthermore, glucose oxidase was immobilized on the Pt-PdBNC structure, and the fabricated biosensor presents favorable properties for glucose sensing., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Mercury is a highly toxic metal that can cause significant harm to humans and aquatic ecosystems. This paper describes a novel approach for mercury (Hg(2+)) ion detection by using label-free oligonucleotide probes and Escherichia coli exonuclease I (Exo I) in a microfluidic electrophoretic separated platform. Two single-stranded DNAs (ssDNA) TT-21 and TT-44 with 7 Thymine-Thymine mispairs are employed to capture mercury ions. Due to the coordination structure of T-Hg(2+)-T, these ssDNAs are folded into hairpin-like double-stranded DNAs (dsDNA) which are more difficult to be digested by Exo I, as confirmed by polyacrylamide gel electrophoresis (PAGE) analysis. A series of microfluidic capillary electrophoretic separation studies are carried out to investigate the effect of Exo I and mercury ion concentrations on the detected fluorescence intensity. This method has demonstrated a high sensitivity of mercury ion detection with the limit of detection around 15 nM or 3 ppb. An excellent selectivity of the probe for mercury ions over five interference ions Fe(3+), Cd(2+), Pb(2+), Cu(2+) and Ca(2+) is also revealed. This method could potentially be used for mercury ion detection with high sensitivity and reliability., (Copyright © 2011 Elsevier B.V. All rights reserved.)