A Novel Non‐Enzymatic Glucose Sensor Based on Cobalt Nanoparticles Implantation‐Modified Indium Tin Oxide Electrode

A new type of cobalt nanoparticles modified indium tin oxide electrode (CoNPs/ITO) was fabricated using ion implantation technique. This method is low‐cost, facile and environmentally friendly without the use of any other chemicals. Electrochemical oxidation of glucose with this sensor was examined by cyclic voltammetry (CV) and chronoamperometry in alkaline aqueous solutions. The proposed sensor exhibited prominent electrocatalytic activity toward the oxidation of glucose with a low limit of detection of 0.25 µM. Furthermore, the fabricated electrode showed excellent selectivity, good reproducibility and long‐term stability. Thus CoNPs/ITO electrode is a promising candidate in the development of non‐enzymatic glucose sensors.     

A Non‐Enzymatic Glucose Sensor Based on Ni/MnO2 Nanocomposite Modified Glassy Carbon Electrode

A novel flower like 3D nickel/manganese dioxide (Ni/MnO₂) nanocomposite was synthesized by a kind of simple electrochemical method and the formation mechanism of flower like structure was also researched. In addition, morphology and composition of the nanocomposite were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), and X‐ray photoelectron spectroscopy (XPS). Then the Ni/MnO₂ nanocomposites were applied to fabricate electrochemical non‐enzymatic glucose sensor. The electrochemical investigation for the sensor indicated that it possessed an excellent electrocatalytic property for glucose, and could applied to the quantification of glucose with a linear range from 2.5×10^?7 to 3.5×10^?3 M, a sensitivity of 1.04 mA mM^?1 cm^?2, and a detection limit of 1×10^?7 M (S/N=3). The proposed sensor also presented attractive features such as interference‐free, and long‐term stability. The present study provided a general platform for the one‐step synthesis of nanomaterials with novel structure and can be extended to other optical, electronic and magnetic nanocompounds.     

A Non‐Enzymatic Hydrogen Peroxide Sensor Based on Gold Nanoparticles/Carbon Nanotube/Self‐Doped Polyaniline Hollow Spheres

In this study, a novel non‐enzymatic hydrogen peroxide (H₂O₂) sensor was fabricated based on gold nanoparticles/carbon nanotube/self‐doped polyaniline (AuNPs/CNTs/SPAN) hollow spheres modified glassy carbon electrode (GCE). SPAN was in‐site polymerized on the surface of SiO₂ template, then AuNPs and CNTs were decorated by electrostatic absorption via poly(diallyldimethylammonium chloride). After the SiO₂ cores were removed, hollow AuNPs/CNTs/SPAN spheres were obtained and characterized by transmission electron microscopy (TEM), field‐emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). The electrochemical catalytic performance of the hollow AuNPs/CNTs/SPAN/GCE for H₂O₂ detection was evaluated by cyclic voltammetry (CV) and chronoamperometry. Using chronoamperometric method at a constant potential of ?0.1 V (vs. SCE), the H₂O₂ sensor displays two linear ranges: one from 5 µM to 0.225 mM with a sensitivity of 499.82 µA mM^?1 cm^?2; another from 0.225 mM to 8.825 mM with a sensitivity of 152.29 µA mM^?1 cm^?2. The detection limit was estimated as 0.4 µM (signal‐to‐noise ratio of 3). The hollow AuNPs/CNTs/SPAN/GCE also demonstrated excellent stability and selectivity against interferences from other electroactive species. The sensor was further applied to determine H₂O₂ in disinfectant real samples.     

Immobilized Fullerene C60‐Enzyme‐Based Electrochemical Glucose Sensor

A mixed‐valence cluster of cobalt(II) hexacyanoferrate and fullerene C60‐enzyme‐based electrochemical glucose sensor was developed. A water insoluble fullerene C60‐glucose oxidase (C60‐GOD) was prepared and applied as an immobilized enzyme on a glassy carbon electrode with cobalt(II) hexacyanoferrate for analysis of glucose. The glucose in 0.1 M KCl/phosphate buffer solution at pH = 6 was measured with an applied electrode potential at 0.0 mV (vs Ag/AgCl reference electrode). The C60‐GOD‐based electrochemical glucose sensor exhibited efficient electro‐catalytic activity toward the liberated hydrogen peroxide and allowed cathodic detection of glucose. The C60‐GOD electrochemical glucose sensor also showed quite good selectivity to glucose with no interference from easily oxidizable biospecies, e.g. uric acid, ascorbic acid, cysteine, tyrosine, acetaminophen and galactose. The current of H₂O₂ reduced by cobalt(II) hexacyanoferrate was found to be proportional to the concentration of glucose in aqueous solutions. The immobilized C60‐GOD enzyme‐based glucose sensor exhibited a good linear response up to 8 mM glucose with a sensitivity of 5.60 × 10² nA/mM and a quite short response time of 5 sec. The C60‐GOD‐based glucose sensor also showed a good sensitivity with a detection limit of 1.6 × 10^‐6 M and a high reproducibility with a relative standard deviation (RSD) of 4.26%. Effects of pH and temperature on the responses of the immobilized C60‐GOD/cobalt(II) hexacyanoferrate‐based electrochemical glucose sensor were also studied and discussed.     

碳纸负载碳酸氢镍纳米颗粒的无酶葡萄糖电化学传感器

通过一步水热法在碳纸上原位生长碳酸氢镍纳米颗粒,利用粉末X射线衍射和扫描电子显微镜对材料的结构及形貌进行表征,发现碳纸上负载纯相Ni （HCO₃）₂时具有较多的催化活性位点,利于葡萄糖的催化氧化反应进行。循环伏安法和时间-电流响应曲线表明该电极的检测限为0.98 μmol·L^-1,线性范围为2.95~1.02 mmol·L^-1,灵敏度为935 μA·L·mmol^-1·cm^-2,同时具有优异的选择性及稳定性。此外,该传感器能够实现对乳制品中葡萄糖的快速检测。这些结果表明,过渡金属和导电基底的协同作用会增强复合材料整体的导电性能和催化性能。     

Fabrication of Non‐enzymatic Electrochemical Glucose Sensor Based on Pd−Mn Alloy Nanoparticles Supported on Reduced Graphene Oxide

Mixed metals alloy nanoparticles supported on carbon nanomaterial are the most attractive candidates for the fabrication of non‐enzymatic electrochemical sensor with enhanced electrochemical performance. In this study, palladium‐manganese alloy nanoparticles supported on reduced graphene oxide (Pd?Mn/rGO) are prepared by a simple reduction protocol. Further, a novel enzyme‐free glucose sensing platform is established based on Pd?Mn/rGO. The successful fabrication of Pd?Mn alloy nanoparticles and their attachment at rGO are thoroughly characterized by various microscopic and spectroscopic techniques such as XRD, Raman, TEM and XPS. The electrochemical activity and sensing features of designed material towards glucose detection are explored by amperometric measurments in 0.1 M NaOH at the working voltage of ?0.1 V. Thanks to the newly designed Pd?Mn/rGO nanohybrid for their superior electrorochemical activity towards glucose comprising the admirable sensing features in terms of targeted selectivity, senstivity, two linear parts and good stability. The enhanced electrochemical efficacy of Pd?Mn/rGO electrocatalyst may be credited to the abundant elecrocatalytic active sites formed during the Pd?Mn alloying and the electron transport ability of rGO that augment the electron shuttling phenomenon between the electrode material and targeted analyte.     

Non‐Enzymatic Electrochemical Detection of Glucose with a Gold Nanowire Array Electrode

High‐performance electrodes for in vivo electrochemical detection of glucose (GO) are highly desirable. In this work, we propose a new approach to efficiently and precisely prepare a Au nanowire array electrode (ANAE) with a line width of 78 nm and a large sensor area of 60 mm×60 mm for GO detection. In this approach three techniques, i.e., vacuum sputtering‐deposition, holography photolithography, and argon ion‐beam etching, are integrated. The fabricated ANAE exhibits good performance for GO detection. A linear amperometric response to the oxidation of GO in a concentration range of 0.4–10 mM is observed. The ANAE is characterized by its high detection sensitivity, selectivity, stability and good biocompatibility. All of these make it a promising tool for GO detection and other relevant applications.     

An enhanced Nonenzymatic Electrochemical Glucose Sensor Based on Copper‐Palladium Nanoparticles Modified Glassy Carbon Electrodes

Novel copper‐palladium nanoparticles modified glassy carbon electrodes (Cu−Pd/GC) with enhanced nonenzymatic sensing for glucose were facilely prepared by one‐step electrodeposition. The structure and composition of the prepared nanoparticles were characterized by XRD, SEM, TEM and EDS, respectively. The electrode modified process was characterized by electrochemical impedance spectroscopy. Cyclic voltammetry and chronoamperometric experiments were used to evaluate the electrocatalytic activities of the electrodes toward glucose. The surface morphology and the electrocatalytic activities of Cu−Pd/GC was compared to Pd and Cu nanoparticles modified glassy carbon electrodes (Pd/GC and Cu/GC), respectively. Thanks to homogeneous distribution of Cu−Pd nanoparticles and the synergistic effect of Cu and Pd atoms, Cu−Pd/GC exhibited the highest sensitivity (298 μA mM⁻¹ cm⁻²) and the widest linear amperometric response (0.01 mM to 9.6 mM, R²=0.996) toward glucose compared to Pd/GC and Cu/GC. The detection limit of Cu−Pd/GC was 0.32 μM (S/N=3). In addition, the as‐prepared Cu−Pd/GC glucose sensor also exhibited exceptional capabilities of anti‐interference, reproducibility and long‐term stability. The as‐prepared sensor was also evaluated for determination of glucose concentration in human blood serum samples, which exhibited high reliability and accuracy, having great potential in clinical application.     

Nonenzymatic Electrochemical Glucose Sensor Based on Pt Nanoparticles/Mesoporous Carbon Matrix

A nonenzymatic amperometric sensor for sensitive and selective detection of glucose has been constructed by using highly dispersed Pt nanoparticles supported onto mesoporous carbons (MCs). The Pt nanoparticles/mesoporous carbons (Pt/MCs) composites modified electrode displayed high electrocatalytic activity towards the oxidation of glucose. At an applied potential of 0.1 V, the Pt/MCs electrode has a linear dependence (R=0.996) in the glucose concentration up to 7.5 mM with a sensitivity of 8.52 mA M^?1 cm^?2. The Pt/MCs electrode has also shown highly resistant toward poisoning by chloride ions and without interference from the oxidation of common interfering species.     

Core‐shell structure microcapsules with dual pH‐responsive drug release function

We report dual pH‐responsive microcapsules manufactured by combining electrostatic droplets (ESD) and microfluidic droplets (MFD) techniques to produce monodisperse core (alginate)‐shell (chitosan) structure with dual pH‐responsive drug release function. The fabricated core‐shell microcapsules were size controllable by tuning the synthesis parameters of the ESD and MFD systems, and were responsive in both acidic and alkaline environment, We used two model drugs (ampicillin loaded in the chitosan shell and diclofenac loaded in the alginate core) for drug delivery study. The results show that core‐shell structure microcapsules have better drug release efficiency than respective core or shell particles. A biocompatibility test showed that the core‐shell structure microcapsules presented positive cell viability (above 80%) when evaluated by the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. The results indicate that the synthesized core‐shell microcapsules were a potential candidate of dual‐drug carriers.     

Synthesis of Pyranopyrazoles Using Magnetically Recyclable Heterogeneous Iron Oxide‐silica Core‐shell Nanocatalyst

The Fe₃O₄@SiO₂ core‐shell nanocatalyst were prepared and efficiently used for four‐component coupling reaction of aromatic aldehydes, malononitrile, ethyl acetoacetate and hydrazine hydrate in water/ethanol mixture. Various aromatic aldehydes possessing electron‐withdrawing and electron‐donating groups in different positions on the ring were successfully transformed to substituted pyranopyrazoles in high yields in short time. The nanocatalyst was easily recovered, and reused five times without significant loss in cata‐ lytic activity and performance. The structure, size and morphology of the nanosized catalyst were studied by various techniques such as Fourier transform infrared spectroscopy, powder X‐ray diffraction, dynamic light scattering and transmission electron microscopy.     

Disposable Sandwich‐type Electrochemical Sensor for Selective Detection of Glucose Based on Boronate Affinity

A disposable sandwich‐type electrochemical sensor for selective detection of glucose was established. The primary receptor, 3‐aminophenylboronic acid was grafted covalently onto the surface of screen‐printed carbon electrodes through an in situ‐generated diazo‐reaction. Glucose was first captured by boronic acid group on the electrode, followed by captureing an electroactive ferroceneboronic acid (FcBA) as the secondary receptor to form bidentate glucose‐boronic complex. Electrochemical impedance spectroscopy was applied to characterize the construction of sandwich‐type disposable sensor. In the sandwich assay, current response of captured FcBA on the electrode was dependent on the concentration of glucose. The sandwich assay showed higher selectivity for glucose than that for fructose, mannose, galactose and other electroactive interferences including uric acid, ascorbic acid and dopamine, and exhibited a dynamic concentration range of glucose from 0.5 to 20.0 mmol L⁻¹. The disposable sensor demonstrated a good reproducibility with 2.2 % relative standard deviation (RSD). In addition, the disposable glucose sensor was used in detection of the trace glucose in the clinical urine samples.     

Enzymeless Electrochemical Glucose Sensor Based on Carboxylated Multiwalled Carbon Nanotubes Decorated with Nickel (II) Electrocatalyst and Self-assembled Molecularly Imprinted Polyethylenimine

In this paper a new enzymeless electrochemical glucose sensor based on carboxylated multiwalled carbon nanotubes (cMWCNT) with immobilized nickel (II) acetylacetonate (NiL) as electrocatalyst and molecularly imprinted polymer fabricated through electrostatic self-assembling of polyethyleneimine (PEI) crosslinked with glutaric dialdehyde (GDA). The electrocatalytic properties of NiL and PEI-cMWCNT, PEI-GDA and PEI-glucose interactions is studied for the first time. Developed sensor demonstrates excellent electrocatalytic activity towards glucose oxidation and possessing high stability, sensitivity of 5897.42±161.00 μA ⋅ mM⁻¹ cm⁻², LOD of 0.138 mM and high selectivity in the presence of creatinine, L-alanine, glycine, D-glutamine, uric acid, L-ascorbic acid, urea and BSA.     

Biosensor Based on Self‐Assembling Glucose Oxidase and Dendrimer‐Encapsulated Pt Nanoparticles on Carbon Nanotubes for Glucose Detection

A novel amperometric glucose biosensor based on layer‐by‐layer (LbL) electrostatic adsorption of glucose oxidase (GOx) and dendrimer‐encapsulated Pt nanoparticles (Pt‐DENs) on multiwalled carbon nanotubes (CNTs) was described. Anionic GOx was immobilized on the negatively charged CNTs surface by alternatively assembling a cationic Pt‐DENs layer and an anionic GOx layer. Transmission electron microscopy images and ζ‐potentials proved the formation of layer‐by‐layer nanostructures on carboxyl‐functionalized CNTs. LbL technique provided a favorable microenvironment to keep the bioactivity of GOx and prevent enzyme molecule leakage. The excellent electrocatalytic activity of CNTs and Pt‐DENs toward H₂O₂ and special three‐dimensional structure of the enzyme electrode resulted in good characteristics such as a low detection limit of 2.5 μM, a wide linear range of 5 μM–0.65 mM, a short response time (within 5 s), and high sensitivity (30.64 μA mM^?1 cm^?2) and stability (80% remains after 30 days).     

Metal Chelate Monomers Based on Nickel Maleate and Chelating N‐Heterocycles as Precursors of Core‐shell Nanomaterials with Advanced Tribological Properties

In this study, new metal chelate monomers based on nickel(II) maleate and chelating N‐heterocycles (2,2′‐bipyridine and 1,10‐phenanthroline) were synthesized and characterized. A detailed analysis of the main stages and features of the kinetics of thermal transformations of metal chelate monomers was carried out. Core‐shell nanomaterials containing nanoparticles of nickel oxide and metallic nickel in a stabilizing nitrogen‐containing polymer matrix were obtained by thermolysis of these monomers. The composition, properties and structure of the nanomaterials were studied using IR spectroscopy, thermal analysis, X‐ray diffraction, atomic force microscopy, scanning electron microscopy, high‐resolution transmission electron microscopy, and energy dispersive X‐ray spectroscopy. The tribological characteristics of NiO nanoparticles as lubricant additives were studied using a pin‐on‐disc tribometer. The coefficient of friction (COF) is the lowest at the optimum concentration of nanoparticles and increasing the concentration above the optimum level leads to an increase in COF.     

Fabrication and Characterization of Sulfonate‐containing Polystyrene/CaCO3 Core‐shell Nanoparticles

Polystyrene (PSt) seed latex was first prepared via soap‐free emulsion polymerization in the presence of a small amount of methacrylic acid using ammonium persulfate as initiator, and then seeded emulsion polymerization of sodium 4‐styrenesulfonate (NaSS) and St was carried out to synthesize P(St‐NaSS) core latex using 2,2′‐azobisisobutyronitrile as initiator. After that, P(St‐NaSS)/CaCO₃ core‐shell nanoparticles were fabricated by sequentially introducing Ca(OH)₂ aqueous solution and CO₂ gas into the core latex. The morphology of the core and core‐shell nanoparticles was characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM), and the state of CaCO₃ shell was confirmed with high‐resolution scanning transmission electron microscope (HR‐STEM) and selected area electron diffraction (SAED). Results showed that PNaSS chains were successfully grafted onto the PSt seed surface, and length of the PNaSS "hairs" could be modulated by adjusting NaSS amount. Sulfonic groups of the PNaSS hairs served as additives in the formation and stabilization of amorphous CaCO₃(ACC) and prevented ACC from sequent transformation into crystalline states. The amount of the anchored CaCO₃ increased with the growth of PNaSS hair length, and reached 51 wt% (by thermalgravimetric analysis) under the optimal encapsulating temperature of 45°C. Moreover, the forming mechanism of P(St‐NaSS)/CaCO₃ core‐shell nanoparticles was proposed.     

A Novel Electrochemical Sensor for Detection of Baicalein in Human Serum Based on DUT‐9/Mesoporous Carbon Composite

DUT‐9/mesoporous carbon (DUT‐9/MC) nanocomposites were synthesized by in‐situ growth of nickel‐based metal‐organic frameworks (DUT‐9) on the MC for the first time. Compared with original DUT‐9 crystals, the presence of MC in the composites can avoid the agglomeration of DUT‐9 sheets, increase the specific surface area and reduce the electron transfer resistance. DUT‐9/MC shows enhanced electrocatalytic activity toward redox of baicalein compared with DTU‐9. The possible electrocatalytic redox mechanism of baicalein involves two electrons and two protons. Under the optimized conditions, the proposed sensor shows a wide linear relationship in the concentration range of 0.05‐20 μM (R²=0.993, sensitivity of 0.1188 μA/μM) with a low detection limit of 0.015 μM. It is worth noting that the oxidation overpotential of baicalein (0.107 V) is significantly lower than that of most literatures in pH 7.0. Meanwhile, the proposed sensor shows satisfactory results for the detection of baicalein in human serum samples. This research provides a highly efficient strategy for fabricating novel electrochemical sensor based two‐dimensional lamellar structure MOFs.     

Zn0@ZnS Core‐Shell Nanoparticles via Oxidation of Intermediate Zn0 Nanoparticles

Zn⁰@ZnS core‐shell nanoparticles were prepared via reduction of ZnCl₂ to Zn⁰ nanoparticles and subsequent partial oxidation with elemental sulfur. The intermediate, highly reactive Zn⁰ nanoparticles were obtained by sodium naphthalenide ([NaNaph]) reduction of ZnCl₂ in tetrahydrofuran (THF). After centrifugation, the Zn⁰ nanoparticles were redispersed in a solution of sulfur in toluene and oxidized by subsequent heating to reflux. According to electron microscopy (HRTEM, HAADF‐STEM), the Zn⁰@ZnS core‐shell nanoparticles exhibit a mean outer diameter of 12 ± 4 nm, consisting of an inner Zn⁰ core (8 nm in diameter) and a ZnS shell (2 nm in diameter). HRTEM and XRD confirm the crystallinity of both core and shell. The Zn⁰@ZnS nanostructure shows synergistic properties of core and shell: the ZnS layer efficiently passivates the reactive Zn⁰ metal core against oxidation, whereas the optical properties point to dominating metallic behavior of the Zn⁰ metal core despite of the ZnS shell.