ZnO nanorods anchored on CNTs incorporating carbon cloth flexible electrode as a highly sensitive electrochemical sensor.

Monitoring glucose, uric acid (UA) and hydrogen peroxide (H2O2) concentration has emerged as a critical health care issue to prevent acute complications and to minimize the hazard of long-term complications. In this paper, a novel non-enzyme electrochemical sensor was proposed with nanorod-like zinc oxide anchored on carbon nanotubes using a direct precipitation method and then decorated onto carbon cloth (ZnO/CNTs/CC). The ZnO/CNTs composite was characterized by x-ray photoelectron spectroscopy (XPS), Raman spectrum, TEM microscope and electrochemistry. The sensing of UA, glucose and H2O2individually or simultaneously was done on a ZnO/CNTs/CC electrode, and the superior performance lies in its wide linear range, low detection limit and high selectivity, which is attributed to the synergistic effect of (a) the good electrocatalytic activity of ZnO nanorods, and (b) the large surface area with high conductivity offered by CNTs. Moreover, the ZnO/CNTs/CC electrode showed good reproducibility, stability and selectivity. Importantly, the developed sensor platform has been successfully applied to probe glucose, UA and H2O2in human serum with satisfactory recoveries. Our proposed approach is simple in fabrication and operation, which provides a straightforward assay for the reliable and cost-effective determination of glucose, UA and H2O2in clinical diagnosis and biomedical applications.

Glucose and UA sensing based on Cu nanoparticle decorated Nif/GO flexible electrode.

A novel, green, and facile approach has been developed to construct an ultrasensitive flexible enzyme-less electrochemical sensor on the basis of chitosan and graphene oxide composites decorated with Cu nanoparticles supported on nickel foam (Nif/Cs/GO@Cu), in which GO functions as the intermediate between Nif and Cu nanoparticles. The Nif/Cs/GO@Cu sensing platform was successfully fabricated by the drop casting method to load Cs/GO onto Nif followed by an additionally electrodeposition to support Cu nanoparticles on Nif/Cs/GO. Impressively, the Nif/Cs/GO@Cu exhibited much higher electrocatalytic activity for glucose and UA oxidation as compared to that of Nif or Nif@Cu. For glucose and UA at about 0.6 V and 0.1 V (vs. Ag/AgCl), linearity could be obtained in the concentration ranges 5 µM-4 mM and 5-345 µM; the sensitivities were 16 and 2.5 µA µM-1 cm-2, and the detection limits 83 nM and 0.3 µM, respectively. The improved performance of the composite electrode was ascribed to the synergistic effect of Cu nanoparticles, Nif and GO, in which GO provides high electron conductivity and large surface area to prevent the agglomeration of Cu nanoparticles; Cu nanoparticles and Nif offer abundant active sites towards analytes oxidation. Additionally, the method was applied to determine both analytes successfully in blood serum samples with excellent recovery and also opens up an attractive route to potential applications of the flexible nickel foam-based electrochemical sensor.

Electrochemical fabrication of Co(OH)2 nanoparticles decorated carbon cloth for non-enzymatic glucose and uric acid detection.

Cobalt hydroxide nanoparticles (Co(OH)2 NPs) were uniformly deposited on flexible carbon cloth substrate (Co(OH)2@CC) rapidly by a facile one-step electrodeposition, which can act as an enzyme-free glucose and uric acid sensor in an alkaline electrolyte. Compositional and morphological characterization were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), which confirmed the deposited nanospheres were Co(OH)2 nanoparticles (NPs). The electrochemical oxidation of glucose and uric acid at Co(OH)2@CC electrode was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry methods. The results revealed a remarkable electrocatalytic activity toward the single and simultaneous determination of glucose and uric acid at about 0.6 V and 0.3 V (vs. Ag/AgCl), respectively, which is attributed to a noticeable synergy effect between Co(OH)2 NPs and CC with good repeatability, satisfactory reproducibility, considerable long-term stability, superior selectivity, outstanding sensitivity, and wide linear detection range from 1 uM to 2 mM and 25 nM to 1.5 uM for glucose and UA, respectively. The detection limits were 0.36 nM for UA and 0.24 µM for glucose (S/N = 3). Finally, the Co(OH)2@CC electrode was utilized for glucose and uric acid determination in human blood samples and satisfying results were obtained. The relative standard derivations (RSDs) for glucose and UA were in the range 6 to 14% and 0 to 3%, respectively. The recovery ranges for glucose an UA were 97 to 103% and 95 and 101%, respectively. These features make the novel Co(OH)2@CC sensor developed by a low-cost, efficient, and eco-friendly preparation method a potentially practical candidate for application to biosensors.

Self-healable nanocellulose composite hydrogels combining multiple dynamic bonds for drug delivery.

Herein, we developed two nanocomposite polysaccharide hydrogels TPP-CNC and TPP-CNF via simple mixing method, which were constructed with multiple dynamic bonds. The microstructural features, mechanical properties, rheological properties, healable ability and biocompatibility of the complex hydrogels were evaluated. The TPP-CNC and TPP-CNF complex hydrogels exhibited higher tensile strength than pure polysaccharide hydrogel, from ~259 KPa to ~890 KPa and ~910 KPa, respectively, that was attributed to the contribution of ionic crosslinked network and hydrogen bonds. In addition, the hydrogels indicated superior fatigue resistance and high energy dissipation ratio during loading-unloading tests because of the physical sacrifice bonds, which also decreased the self-healing time at room temperature (~15 min). More importantly, the drug loaded nanocomposite hydrogels showed sustained release, reduction burst release, increased release under acidic environment, and the drug release kinetics belonged to Fickian diffusion mechanism. Therefore, the nanocellulose polysaccharide hydrogels have the highly promising to explore as biomaterials for drug delivery.

A Non-Enzymatic Sensor Based on Fc-CHIT/CNT@Cu Nanohybrids for Electrochemical Detection of Glucose.

Herein, a composite structure, consisting of Cu nanoparticles (NPs) deposited onto carbon nanotubes and modified with ferrocene-branched chitosan, was prepared in order to develop a nonenzymatic electrochemical glucose biosensor ferrocene-chitosan/carbon nanotube@ Cu (Fc-CHIT/CNT@Cu). The elemental composition of the carbon nanohybrids, morphology and structure were characterized by various techniques. Electrochemical impedance spectroscopy (EIS) was used to study the interfacial properties of the electrodes. Cyclic voltammetry (CV) and chronoamperometry methods in alkaline solution were used to determine glucose biosensing properties. The synergy effect of Cu NPs and Fc on current responses of the developed electrode resulted in good glucose sensitivity, including broad linear detection between 0.2 mM and 22 mM, a low detection limit of 13.52 µM and sensitivity of 1.256 µA mM-1cm-2. Moreover, the modified electrode possessed long-term stability and good selectivity in the presence of ascorbic acid, dopamine and uric acid. The results indicated that this inexpensive electrode had potential application for non-enzymatic electrochemical glucose detection.