Ni-Rh-based bimetallic conductive MOF as a high-performance electrocatalyst for the oxygen evolution reaction

Metal-organic frameworks (MOFs) have recently been considered the promising catalysts due to their merits of abundant metal sites, versatile coordination groups, and tunable porous structure. However, low electronic conductivity of most MOFs obstructs their direct application in electrocatalysis. In this work, we fabricate an Ni-Rh bimetallic conductive MOF ([Ni2.85Rh0.15(HHTP)2]n/CC) grown in situ on carbon cloth. Abundant nanopores in the conductive MOFs expose additional catalytic active sites, and the advantageous 2D π-conjugated structure helps accelerate charge transfer. Owing to the introduction of Rh, [Ni2.85Rh0.15(HHTP)2]n/CC exhibited substantially improved oxygen evolution reaction (OER) activity and exhibited only an overpotential of 320 mV to achieve the current density of 20 mA cm-2. The remarkable OER performance confirmed by the electrochemical tests could be ascribed to the synergistic effect caused by the doped Rh together with Ni in [Ni2.85Rh0.15(HHTP)2]n/CC, thereby exhibiting outstanding electrocatalytic performance.

Stimulus-responsive nanomaterials under physical regulation for biomedical applications

Cancer is a growing threat to human beings. Traditional treatments for malignant tumors usually involve invasive means to healthy human tissues, such as surgical treatment and chemotherapy. In recent years the use of specific stimulus-responsive materials in combination with some non-contact, non-invasive stimuli can lead to better efficacy and has become an important area of research. It promises to develop personalized treatment systems for four types of physical stimuli: light, ultrasound, magnetic field, and temperature. Nanomaterials that are responsive to these stimuli can be used to enhance drug delivery, cancer treatment, and tissue engineering. This paper reviews the principles of the stimuli mentioned above, their effects on materials, and how they work with nanomaterials. For this aim, we focus on specific applications in controlled drug release, cancer therapy, tissue engineering, and virus detection, with particular reference to recent photothermal, photodynamic, sonodynamic, magnetothermal, radiation, and other types of therapies. It is instructive for the future development of stimulus-responsive nanomaterials for these aspects.

Synthesis of Cu(OH)F microspheres using atmospheric dielectric barrier discharge microplasma: a high-performance non-enzymatic electrochemical sensor

Cu(OH)F microspheres were in situ synthetized using microplasma and were employed as an electrochemical sensor for glucose, hydrogen peroxide and formaldehyde.

Progress of Advanced Nanomaterials in the Non-Enzymatic Electrochemical Sensing of Glucose and H2O2

Non-enzymatic sensing has been in the research limelight, and most sensors based on nanomaterials are designed to detect single analytes. The simultaneous detection of analytes that together exist in biological organisms necessitates the development of effective and efficient non-enzymatic electrodes in sensing. In this regard, the development of sensing elements for detecting glucose and hydrogen peroxide (H₂O₂) is significant. Non-enzymatic sensing is more economical and has a longer lifetime than enzymatic electrochemical sensing, but it has several drawbacks, such as high working potential, slow electrode kinetics, poisoning from intermediate species and weak sensing parameters. We comprehensively review the recent developments in non-enzymatic glucose and H₂O₂ (NEGH) sensing by focusing mainly on the sensing performance, electro catalytic mechanism, morphology and design of electrode materials. Various types of nanomaterials with metal/metal oxides and hybrid metallic nanocomposites are discussed. A comparison of glucose and H₂O₂ sensing parameters using the same electrode materials is outlined to predict the efficient sensing performance of advanced nanomaterials. Recent innovative approaches to improve the NEGH sensitivity, selectivity and stability in real-time applications are critically discussed, which have not been sufficiently addressed in the previous reviews. Finally, the challenges, future trends, and prospects associated with advanced nanomaterials for NEGH sensing are considered. We believe this article will help to understand the selection of advanced materials for dual/multi non-enzymatic sensing issues and will also be beneficial for researchers to make breakthrough progress in the area of non-enzymatic sensing of dual/multi biomolecules.

Biomolecule conjugated metal nanoclusters: bio-inspiration strategies, targeted therapeutics, and diagnostics

To help those suffering from viral infections and cancers, scientists are exploring enhanced therapeutic methods via metal nanoclusters (MNCs).

A novel hydrogen peroxide sensor based on electrodeposited copper/cuprous oxide nanocomposites

Copper/cuprous oxide nanocomposites were electrodeposited on a fluorine doped tin oxide (FTO) glass substrate for sensitive determination of hydrogen peroxide.

Reduced Graphene Oxide-Based Double Network Polymeric Hydrogels for Pressure and Temperature Sensing

We demonstrate the fabrication of novel reduced graphene oxide (rGO)-based double network (DN) hydrogels through the polymerization of poly(N-isopropylacrylamide) (PNIPAm) and carboxymethyl chitosan (CMC). The facile synthesis of DN hydrogels includes the reduction of graphene oxide (GO) by CMC, and the subsequent polymerization of PNIPAm. The presence of rGO in the fabricated PNIPAm/CMC/rGO DN hydrogels enhances the compressibility and flexibility of hydrogels with respect to pure PNIPAm hydrogels, and they exhibit favorable thermoresponsivity, compressibility, and conductivity. The created hydrogels can be continuously cyclically compressed and have excellent bending properties. Furthermore, it was found that the hydrogels are pressure- and temperature-sensitive, and can be applied to the design of both pressure and temperature sensors to detect mechanical deformation and to measure temperature. Our preliminary results suggest that these rGO-based DN hydrogels exhibit a high potential for the fabrication of soft robotics and artificially intelligent skin-like devices.

Developing Graphene-Based Nanohybrids for Electrochemical Sensing

Graphene-based nanohybrid is considered to be the most promising nanomaterial for electrochemical sensing applications due to the defects created on the graphene oxide layers. These defects provide graphene oxide unique properties, such as excellent conductivity, large specific surface area, and electrocatalytic activity. These unique properties encourage scientists to develop novel graphene-based nanohybrids and improve the sensing efficiency. This review, therefore, addresses this topic by comprehensively discussing the strategies to fabricate novel graphene based nanohybrids with high sensitivity. The combinations of graphene with various nanomaterials, such as metal nanoclusters, metal compound nanoparticles, carbon materials, polymers and peptides, in the direction of electrochemical sensing, were systematically analyzed. Meanwhile, the challenges in the functional design and application of graphene-based nanohybrids were described and the reasonable solutions were proposed.

Preparation of gold nanoparticles supported on graphene oxide with flagella as the template for nonenzymatic hydrogen peroxide sensing

Gold nanoparticles supported on graphene oxide with flagella as the template were developed as an electrochemical sensor for the detection of hydrogen peroxide (H₂O₂) in serum. The flagella-Au nanoparticles composite and graphene oxide were dropped onto a glassy carbon electrode (GCE) to form a new H₂O₂ electrochemical sensor. The structure morphology of the prepared sensor was characterized by transmission electron microscopy (TEM), and the electrocatalytic performance towards H₂O₂ reduction was evaluated by cyclic voltammetry (CV) and amperometric methods. The response current of the sensor showed a good linear relationship with the concentration of H₂O₂ in the range of 10-1000 μM (R² = 0.9916). The minimum detection limit of 1 μM was obtained (S/N = 3). Finally, the sensor was applied to the detection of H₂O₂ in serum, and the recoveries were satisfactory. As the sensor is sensitive, fast, and easy to make, it is expected to be used for rapid detection of H₂O₂. Graphical abstract ᅟ.

Self-Assembled Ag-Cu₂O Nanocomposite Films at Air-Liquid Interfaces for Surface-Enhanced Raman Scattering and Electrochemical Detection of H₂O₂

We employ a facile and novel route to synthesize multifunctional Ag-Cu₂O nanocomposite films through the self-assembly of nanoparticles at an air-liquid interface. In the ethanol-water phase, AgNO₃ and Cu(NO₃)₂ were reduced to Ag-Cu₂O nanoparticles by NaBH₄ in the presence of cinnamic acid. The Ag-Cu₂O nanoparticles were immediately trapped at the air-liquid interface to form two-dimensional nanocomposite films after the reduction reaction was finished. The morphology of the nanocomposite films could be controlled by the systematic regulation of experimental parameters. It was found that the prepared nanocomposite films serving as the substrates exhibited strong surface-enhanced Raman scattering (SERS) activity. 4-aminothiophenol (4-ATP) molecules were used as the test probes to examine the SERS sensitivity of the nanocomposite films. Moreover, the nanocomposite films synthesized by our method showed enhanced electrocatalytic activity towards hydrogen peroxide (H₂O₂) and therefore could be utilized to fabricate a non-enzymatic electrochemical H₂O₂ sensor.

CoS2-decorated ionic liquid-functionalized graphene as a novel hydrazine electrochemical sensor

Cobalt disulfide-decorated ionic liquid-functionalized graphene nanocomposites were prepared herein and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The as-prepared nanocomposites were subsequently used to build a modified glassy carbon electrode serving as a hydrazine (N₂H₄) electrochemical sensor. The electrocatalytic performance of the prepared sensor towards the N₂H₄ oxidation reaction was evaluated by cyclic voltammetry (CV) and amperometric methods. A linear dependence was found between the oxidation peak current and the concentration of N₂H₄. Thus, linear calibration plots were obtained over wide linear ranges of 5-100 μM (R² = 0.9898) and 100-400 μM (R² = 0.9852), with a relatively low detection limit of 0.39 μM (S/N = 3). The prepared sensor exhibited good electrocatalytic performance (i.e., sensitivity, reproducibility, and selectivity) towards the detection of N₂H₄. The sensor was successfully used for the practical determination of N₂H₄ in lake water samples with satisfactory recoveries.

One-step green hydrothermal synthesis of biocompatible graphene/TiO2 nanocomposites for non-enzymatic H2O2 detection and their cytotoxicity effects on human keratinocyte and lung fibroblast cells

A simple, safe, and efficient approach to synthesise graphene/titanium dioxide (G/TiO₂) nanocomposites with potential in electrochemical sensing application and relatively good biocompatibility to human cells.

Evaluation of Graphene/WO3 and Graphene/CeO x Structures as Electrodes for Supercapacitor Applications

The combination of graphene with transition metal oxides can result in very promising hybrid materials for use in energy storage applications thanks to its intriguing properties, i.e., highly tunable surface area, outstanding electrical conductivity, good chemical stability, and excellent mechanical behavior. In the present work, we evaluate the performance of graphene/metal oxide (WO3 and CeO x ) layered structures as potential electrodes in supercapacitor applications. Graphene layers were grown by chemical vapor deposition (CVD) on copper substrates. Single and layer-by-layer graphene stacks were fabricated combining graphene transfer techniques and metal oxides grown by magnetron sputtering. The electrochemical properties of the samples were analyzed and the results suggest an improvement in the performance of the device with the increase in the number of graphene layers. Furthermore, deposition of transition metal oxides within the stack of graphene layers further improves the areal capacitance of the device up to 4.55 mF/cm2, for the case of a three-layer stack. Such high values are interpreted as a result of the copper oxide grown between the copper substrate and the graphene layer. The electrodes present good stability for the first 850 cycles before degradation.

Designed graphene-peptide nanocomposites for biosensor applications: A review

The modification of graphene with biomacromolecules like DNA, protein, peptide, and others extends the potential applications of graphene materials in various fields. The bound biomacromolecules could improve the biocompatibility and bio-recognition ability of graphene-based nanocomposites, therefore could greatly enhance their biosensing performances on both selectivity and sensitivity. In this review, we presented a comprehensive introduction and discussion on recent advance in the synthesis and biosensor applications of graphene-peptide nanocomposites. The biofunctionalization of graphene with specifically designed peptides, and the synthesis strategies of graphene-peptide (monomer, nanofibrils, and nanotubes) nanocomposites were demonstrated. On the other hand, the fabrication of graphene-peptide nanocomposite based biosensor architectures for electrochemical, fluorescent, electronic, and spectroscopic biosensing were further presented. This review includes nearly all the studies on the fabrication and applications of graphene-peptide based biosensors recently, which will promote the future developments of graphene-based biosensors in biomedical detection and environmental analysis.

Synthesis of graphene-transition metal oxide hybrid nanoparticles and their application in various fields

Single layer graphite, known as graphene, is an important material because of its unique two-dimensional structure, high conductivity, excellent electron mobility and high surface area. To explore the more prospective properties of graphene, graphene hybrids have been synthesised, where graphene has been integrated with other important nanoparticles (NPs). These graphene-NP hybrid structures are particularly interesting because after hybridisation they not only display the individual properties of graphene and the NPs, but also they exhibit further synergistic properties. Reduced graphene oxide (rGO), a graphene-like material, can be easily prepared by reduction of graphene oxide (GO) and therefore offers the possibility to fabricate a large variety of graphene-transition metal oxide (TMO) NP hybrids. These hybrid materials are promising alternatives to reduce the drawbacks of using only TMO NPs in various applications, such as anode materials in lithium ion batteries (LIBs), sensors, photocatalysts, removal of organic pollutants, etc. Recent studies have shown that a single graphene sheet (GS) has extraordinary electronic transport properties. One possible route to connecting those properties for application in electronics would be to prepare graphene-wrapped TMO NPs. In this critical review, we discuss the development of graphene-TMO hybrids with the detailed account of their synthesis. In addition, attention is given to the wide range of applications. This review covers the details of graphene-TMO hybrid materials and ends with a summary where an outlook on future perspectives to improve the properties of the hybrid materials in view of applications are outlined.

Recent advancements, key challenges and solutions in non-enzymatic electrochemical glucose sensors based on graphene platforms

This review elucidates the recent advances in graphene platforms in electrochemical non-enzymatic glucose sensors and provides solutions for existing bottlenecks.

Zinc ion mediated synthesis of cuprous oxide crystals for non-enzymatic glucose detection

Zn²⁺ was used to mediate the fabrication of Cu₂O crystals with different glucose sensing performances depending on their structures.

A controllable honeycomb-like amorphous cobalt sulfide architecture directly grown on the reduced graphene oxide–poly(3,4-ethylenedioxythiophene) composite through electrodeposition for non-enzyme glucose sensing

A facile, controllable two-step electrodeposition route was developed, whereby a honeycomb-like amorphous Co_xS_y architecture was obtained via direct growth on rGO–PEDOT/GCE as an electrode for glucose detection.

When biomolecules meet graphene: from molecular level interactions to material design and applications

Graphene-based materials have attracted increasing attention due to their atomically-thick two-dimensional structures, high conductivity, excellent mechanical properties, and large specific surface areas. The combination of biomolecules with graphene-based materials offers a promising method to fabricate novel graphene-biomolecule hybrid nanomaterials with unique functions in biology, medicine, nanotechnology, and materials science. In this review, we focus on a summarization of the recent studies in functionalizing graphene-based materials using different biomolecules, such as DNA, peptides, proteins, enzymes, carbohydrates, and viruses. The different interactions between graphene and biomolecules at the molecular level are demonstrated and discussed in detail. In addition, the potential applications of the created graphene-biomolecule nanohybrids in drug delivery, cancer treatment, tissue engineering, biosensors, bioimaging, energy materials, and other nanotechnological applications are presented. This review will be helpful to know the modification of graphene with biomolecules, understand the interactions between graphene and biomolecules at the molecular level, and design functional graphene-based nanomaterials with unique properties for various applications.

A novel approach towards hydrazine sensor development using SrO·CNT nanocomposites

Strontium oxide nanoparticle decorated carbon nanotube nanocomposites (SrO·CNT NCs) were prepared in alkaline medium using a wet-chemical technique at low temperature.

Fast preparation of MoS2 nanoflowers decorated with platinum nanoparticles for electrochemical detection of hydrogen peroxide

MoS₂ nanoflowers decorated with Pt nanoparticles show enhanced performances for electrochemical H₂O₂ sensing.

Newly reduced graphene oxide/gold oxide neural-chemical interface on multi-channel neural probes to enhance the electrochemical properties for biosensors

The newly neural-chemical interface designed by rGO-wrapped gold oxide nanocomposites on multi-channel neural probes as a biosensor.

Nanoporous Carbon Nanofibers Decorated with Platinum Nanoparticles for Non-Enzymatic Electrochemical Sensing of H₂O₂

We describe the preparation of nanoporous carbon nanofibers (CNFs) decorated with platinum nanoparticles (PtNPs) in this work by electrospining polyacrylonitrile (PAN) nanofibers and subsequent carbonization and binding of PtNPs. The fabricated nanoporous CNF-PtNP hybrids were further utilized to modify glass carbon electrodes and used for the non-enzymatic amperometric biosensor for the highly sensitive detection of hydrogen peroxide (H₂O₂). The morphologies of the fabricated nanoporous CNF-PtNP hybrids were observed by scanning electron microscopy, transmission electron microscopy, and their structure was further investigated with Brunauer-Emmett-Teller (BET) surface area analysis, X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectrum. The cyclic voltammetry experiments indicate that CNF-PtNP modified electrodes have high electrocatalytic activity toward H₂O₂ and the chronoamperometry measurements illustrate that the fabricated biosensor has a high sensitivity for detecting H₂O₂. We anticipate that the strategies utilized in this work will not only guide the further design and fabrication of functional nanofiber-based biomaterials and nanodevices, but also extend the potential applications in energy storage, cytology, and tissue engineering.

Fabrication of polypyrrole nanoplates decorated with silver and gold nanoparticles for sensor applications

The PPyNPT–Ag and PPyNPT–Au nanohybrids fabricated by self-assembly process exhibit excellent electrocatalytic activity toward H₂O₂ and DA, respectively.

Optimal hydrothermal synthesis, characterization, and sensor application of sulfur-doped γ-MnOOH microrods

We demonstrate the optimal hydrothermal synthesis of S-doped γ-MnOOH microrods for highly sensitive electrochemical detection of hydrazine.