To explore electrochemistry of the composites of ZnO and reduced graphene oxides (rGO), graphene oxide (GO) was in-situ reduced with Zn powders. The morphology and micro-structure of synthesized ...ZnO@rGO composites were characterized using scanning electron microscopy, transmission electron microscopy, and atomic force microscope. Energy dispersive spectroscopy, X-ray diffraction, Raman, and Fourier Transform infrared spectroscopy were employed to clarify the chemical composition of ZnO@rGO composites. Electrochemical properties of ZnO@rGO composites were studied using cyclic voltammetry and impedance, revealing a large surface area and many active sites. Accordingly, electrochemical sensing of a neutral organic dye Sudan I and a charged metal ion Pb2+ was achieved on ZnO@rGO composites. The strategy of in-situ reduction of GO with Zn powders thus owns great application prospects in constructing a universal and sensitive electrochemical sensing platform.
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The simultaneous determination of xanthine (XA) and hypoxanthine (HXA) has been proved to be a feasible approach for the assessment of fish freshness. In this study, copper(II) nitrate and ...1,3,5-benzenetricarboxylic acid (H3BTC) were used as precursors to prepare various Cu-BTC frameworks with the addition of various amounts of triethylamine at room temperature. The characterization of X-ray diffraction, Fourier-transform infrared spectroscopy and Raman spectroscopy testified that the obtained materials are Cu-BTC frameworks. However, the amount of triethylamine had significant effects on the morphology, active response area and electron transfer ability of Cu-BTC frameworks. The oxidation behavior of XA and HXA demonstrated that the prepared Cu-BTC frameworks exhibited higher sensing activity, with greatly-enhanced oxidation signals. More importantly, the amount of triethylamine obviously affected the accumulation capacity and signal enhancement ability of Cu-BTCs toward XA and HXA, as confirmed from double potential step chronocoulometry. Based on the triethylamine-tuned signal amplification strategy of Cu-BTC frameworks, a highly-sensitive and simple electrochemical sensing system was developed for the assessment of fish freshness by simultaneous detection of XA and HXA. The developed sensing method was used in practical samples, and the results were validated by high-performance liquid chromatography.
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•A strategy for regulating morphology and sensing performance of Cu-BTC frameworks.•Morphology-dependent electrochemical signal amplification strategy for XA and HXA.•Highly-sensitive and convenient sensing system for evaluation of fish freshness.
Cancer cells are a class of important tumor biomarkers and are closely related to tumorous progression. It is urgent to develop a sensitive and highly efficient method for the rapid and accurate ...detection of cancer cells. Herein, an aptamer sandwiched nanochannel electrochemical sensor was established for the highly selective determination of cancer cells. By virtue of the porous nanochannels as the filter platform and immobilized with DNA aptamers for specifically capturing the cancer cells, the nanochannel‐based electrochemical sensor denotes excellent performance for MCF‐7 screening, and allowing a low limit of detection of 36 cells mL−1. The nanochannels‐based sandwich structure aptasensor not only presents an efficacious and reliable approach for cancer cell detection but also provides great advantage for preventing electrode passivation in the process of biomarkers analysis.
An aptamer sandwiched nanochannel electrochemical sensor was constructed for the highly selective determination of cancer cells. The structure design of nanochannel composite aptasensor not only presents an efficacious and reliable approach for cancer cell detection but also provides advantage for preventing electrode passivation in the process of biomarkers analysis.
Transition metal sulfides have garnered significant interest in the realm of photoelectrochemical (PEC) sensors due to their remarkable optical and electrical properties. However, their intrinsic ...UV–vis adsorption and electron‐donor consumption severely hinder their nonirritating and in situ epidermal PEC applications. Herein, a NIR‐808 nm light‐excited heterojunction, phosphomolybdic acid‐encapsulated ytterbium‐doped bismuth sulfide (Yb‐Bi2S3/PMA), is synthesized by hydrothermal method for self‐sufficient electron donor‐based PEC sensing. Further, the Yb‐Bi2S3/PMA heterojunction is decorated on flexible and integrated laser‐induced graphene electrode arrays, providing ultrafast charge carrier transfer capacity and robust mechanical durability (300 bending cycles) for subsequent wearable PEC sensing. As a showcase, the aptamer molecular recognition‐based wearable PEC sensor for sweat trace Neuropeptide Y (NPY, a stress or depression biomarker) presents an ultra‐low detection limit (0.39 fM) and good anti‐interference ability. Moreover, the integration of wearable PEC aptasensor with signal processing and wireless communication facilitates nonirritating and in situ analysis of sweat trace NPY dynamics in various real scenarios (feeding behaviors, physiological stress, and circadian rhythm). More broadly, this research establishes the foundation for NIR‐excitable semiconductors equipped with self‐sufficient electron donor capabilities, unlocking the potential for ultrasensitive wearable PEC sensing applications.
This study paves the way for NIR‐excitable semiconductors with inherent self‐sufficient electron donor capabilities, highlighting the promising application of LIG‐Yb‐Bi2S3/PMA photoelectrode materials in ultrasensitive PEC sensing. Moreover, a wearable PEC aptasensor, integrated with an intelligent signal interaction system, is devised to enable nonirritating and in situ analysis of trace NPY dynamics in sweat during daily activities.
The cost-effective construction of self-designed conductive graphene patterns on desired substrates is crucial to the fabrication of graphene-based electrochemical devices. Here, we report a new ...approach for the scalable construction of laser-induced graphene (LIG) patterns on diverse substrates by using phenolic resin (PR) as the precursor. The PR-based LIG, which was produced with smart and inexpensive 405 nm semiconductor lasers under ambient conditions, possesses several interesting properties, e.g., 3D porous structures, low resistance (∼44 Ω/sq), good mechanical property and a wide range of applicable substrates, e.g., polymer films, glass slides, metal foils, ceramic plates and plant leaves. The efficient absorption of laser light by PR coatings themselves or dopants such as metal salts and organic dyes is demonstrated critical to the formation of PR-based LIG by visible light lasers. Based on this technique, self-designed and highly conductive graphene arrays can be easily constructed on various substrates to fabricate all-carbon supercapacitors and electrochemical glucose biosensors. The unique properties of PR materials, including easy synthesis, tunable structure and composition, excellent film-formation ability and extremely low cost, thus foresee the promising applications of PR-based LIG in electrochemical fields.
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Using graphene oxides (GO) as carbon source and NaCl crystals as the solid dispersant, a three-dimensional carbon-based nanohybrid was prepared by anchoring carbon shells-encapsulated Ni ...nanoparticles onto the reduced graphene oxides nanosheets (Ni@C@rGO). The as-obtained Ni@C@rGO exhibits larger specific surface area and pore volume as well as higher reactivity toward glucose oxidation, compared with the prepared Ni@rGO by the same conditions without NaCl crystals. The higher electrochemical reactivity may be originated from the ultrathin carbon shells, high dispersion of active Ni nanoparticles, and high conductivity of the graphene substrates. To further explore its electrochemical applications, Ni@C@rGO was employed to construct a glucose sensing platform, offering a low detection limit (0.34 μM) and wide linear range (2–951 μM). It was successfully utilized to monitor the glucose level in human serums, and satisfactory results were obtained. This used preparation strategy is in favor of making more nanocomposites with superior electrochemical properties.
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A drop-casting method for the scalable construction of a solar cell-type light-addressable photoelectrochemical (PEC) sensor on commercial phenol resin (PR) plates is reported. The sensor was ...fabricated by laser writing of addressable laser-induced graphene (LIG) electrode arrays on PR plates with ring-disc dual-electrode cell configurations using a 405 nm laser machine. Beneficial from the good hydrophilicity of PR-based LIG and the excellent film formation of bismuth sulfide nanorods (Bi2S3 NRs), uniform Bi2S3 photovoltaic films can be reproducibly deposited onto the LIG disc photoanode array via drop casting modification, which show a sensitive photocurrent response toward thiocholine (TCl) when the ring cathode array was coated with Ag/AgCl. An acetylcholinesterase (AChE)-based PEC biosensor was therefore constructed by a similar drop-casting modification method. The resulting biosensor exhibits good sensitivity toward an AChE inhibitor, i.e., galantamine hydrobromide (GH), with a calibration range of 10–300 μM and a detection limit of 7.33 μM (S/N = 3). Moreover, the biosensor possesses good storage stability, which can achieve the high-throughput screening of AChE inhibitor drugs from traditional Chinese medicines (TCMs). The present work thus demonstrates the promising application of LIG technology in constructing light-addressable PEC sensing devices with high performance and low cost.
A light-addressable 8-well photoelectrochemical (PEC) sensor enables the high-throughput screening of acetylcholinesterase inhibitors using laser-induced graphene (LIG) electrode arrays, which can be massively produced on commercial phenol resin (PR) plates by simple laser engraving and drop-casting methods, and provides a facile approach to the scalable construction of portable high-throughput PEC biosensing platforms with high sensitivity and low cost. Display omitted
Developing reliable and feasible electrochemical sensors for the detection of 8-hydroxy-2′-deoxyguanosine (8-OHdG) is important because the urinary level of 8-OHdG is related to cancer disease. ...Moreover, the co-existed uric acid (UA) as an interference severe affects the sensitive detection of 8-OHdG. Herein, sensitive monitoring of 8-OHdG was conducted using a nanocomposite of reduced graphene oxide (rGO) and ZnO nanoparticles (ZnO@rGO) as the sensing material. This nanocomposite was prepared via in-situ reduction of GO with Zn powders. Compared with those obtained on the unmodified glassy carbon electrode (GCE) and GO modified GCE (GO/GCE) the oxidation signals of 8-OHdG are significantly enhanced on the ZnO@rGO nanocomposite coated GCE (ZnO@rGO/GCE). Moreover, uricase has been employed successfully to eliminate the interferences of UA. A large amount of UA did not affect the oxidation signals of trace level of 8-OHdG. The linear range for the detection of 8-OHdG using ZnO@rGO/GCE was from 5.0 to 5000.0 nM. The detection limit was 1.25 nM calculated from a three-signal-to-noise ratio. The developed monitoring system is sensitive and selective for the determination of 8-OHdG and thus useful in practical applications, such as for the monitoring of 8-OHdG in the clinic urine samples.
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•Electrochemical sensor for nM 8-OHdG using ZnO@rGO nanocomposite.•No interferences of large amount of UA on 8-OHdG determination.•Promising application in the clinic urine sample measurements.
Metal active species combined with N-doped porous carbon nanosheets usually own excellent electrochemical activity and sensing performance owing to its unique microstructure and composition. In this ...work, monodispersed Ni active sites anchored on N-doped porous carbon nanosheets (Ni@N–PCN) were facilely prepared via rational metal-organic frameworks (MOFs) route. Firstly, zeolitic imidazolate frameworks-8 (ZIF-8) was in situ grown on physically-exfoliated graphene nanosheets (GN) with homogeneous sandwich-like structure (ZIF-8@GN). Secondly, nickel bonded ZIF-8@GN hybrids (Ni/ZIF-8@GN) were obtained by ionic exchange reaction, and then transformed into Ni@N–PCN by high-temperature pyrolysis. Benefiting from the monodispersed Ni active sites and highly reactive N-doped porous carbon nanosheets (N–PCN), the as-prepared Ni@N–PCN hybrids displayed superior catalytic performance toward hydrogen peroxide (H2O2) sensing. As a result, a highly sensitive electrochemical sensing platform for H2O2 was fabricated with low detection limit (0.032 μM), wide detection linearity (0.2–2332.8 μM), and high sensitivity (6085 μA cm−2 mM−1). Besides, the as-developed electrochemical sensing platform was successfully applied to detect H2O2 contents in biological medicine and food specimens with satisfied results. This study will provide effective guidance for the preparation of novel metal/N-doped carbon nanomaterials and establishment of high-performance electrochemical sensors.
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•A facile MOFs route is developed to fabricate Ni@N–PCN hybrids with abundant mesopores.•Ni active sites was dispersed on N–PCN with ultrahigh dispersion degree.•A novel and efficient H2O2 electrochemical sensing platform was successfully developed.
Properties of metal–organic frameworks (MOFs) are determined by metal centers, organic ligands, and applied synthesis methods. For electrosynthesis of MOFs, the applied potential is expected to play ...a key role in determining the morphology, thickness, electrochemical properties, and applications of MOFs. Herein, Cu-BTC (H3BTC: 1,3,5-benzenetricarboxylic acid) films are electrosynthesized at different cathodic potentials. They feature different morphologies, thicknesses, and amounts of active copper centers, although they do show similar bonding properties, chemical compositions, phase purity, crystallinity, and surface electronic states of copper centers. Using nicotine amide adenine dinucleotide, the sensing application of these Cu-BTC films is explored, showing potential-dependent catalytic ability. Further monitoring of six other organic compounds (herein xanthine, hypoxanthine, diethylstilbestrol, estradiol, sunset yellow, and tartrazine) reveals the morphology and thickness of Cu-BTC films and the amount of copper centers inside these Cu-BTC films determines the accumulation or sensing ability of Cu-BTC films. Highly sensitive detection of these molecules individually and simultaneously is achieved with Cu-BTC electrosynthesized at −1.30 V. Electrosynthesized Cu-BTC films are thus excellent electrode materials for sensitive sensing of various analytes.
