Carbon nanotube-interconnected ruthenium phthalocyanine nanoparticles used for real-time monitoring of nitric oxide released from vascular endothelial barrier model.

Real-time monitoring of nitric oxide (NO) is of great importance in diagnosing the physiological functions of neurotransmission, cardiovascular, and immune systems. This study reports the carbon nanotube-interconnected ruthenium phthalocyanine nanoparticle nanocomposite and its applicability in construction of an electrochemical platform, which could real-time detect NO released from the vascular endothelial barrier (VEB) model in cell culture medium. The nanocomposite exhibits regular morphology, uniform particle size, and excellent electro-catalytic activity to electrochemical oxidation of NO. Under optimal conditions, the electrochemical device has high sensitivity (0.871 µA µM-1) and can selectively detect NO down to the concentration of 6 × 10-10 M. The human brain microvascular endothelial cells were cultured onto the Transwell support to construct the VEB model. Upon stimulated by L-arginine, NO produced by the VEB diffuses into the bottom chamber of the Transwell, and is real-time monitored by the electrochemical device. Moreover, evaluation of the NO inhibition by drug is realized using the electrochemical device-Transwell platform. This simple and sensitive platform would be of great interesting for evaluating the endothelial function or its pathological states, and screening the related drugs or chemicals.

Photoelectrochemistry hydrogen production based on a Pt nanowires-bridged CdS nanorods array of piezoelectricity-triggered Z-scheme junctions.

A vertical CdS nanorods (CdSNR) array is hydrothermally synthesized on an indium tin oxide (ITO) slice, and a novel Pt nanowires (PtNW)/CdSNR/ITO photoanode is then fabricated after the multipoint-bridging of the CdSNR by the photodeposited transverse PtNW. The piezoelectricity (PE)-enhanced photoelectrochemistry based hydrogen production is studied, giving a photocurrent density of 8.13 mA cm-2 and a PE-enhancement factor as high as 2.45 on this photoanode, and a hydrogen yield of 0.132 mmol cm-2 h-1 on a Pt cathode under optimized conditions. A new concept of PE-triggered Z-scheme (or S-scheme) CdSNR-PtNW-CdSNR junctions as the first example of external-field-triggered photoelectric junctions in the field is put forward to discuss the excellent hydrogen-production performance.

Piezoelectricity-enhanced photoelectrochemistry synthesis of H2O2 on an Au nanoparticles modified p-type Sb-doped ZnO nanotubes array.

A p-type Sb-doped ZnO nanorods (p-ZnOSb,NR) array was hydrothermally prepared on indium tin oxide (ITO) and then etched into a p-type Sb-doped ZnO nanotubes (p-ZnOSb,NT) array by hot alkali solution. Further photodeposition of Au nanoparticles (AuNP) yielded a novel AuNP/p-ZnOSb,NT/ITO photocathode. The green synthesis of H2O2 by piezoelectricity-enhanced photoelectrochemistry and oxygen reduction reaction was studied for the first time, giving a H2O2 yield of 15.2 µmol cm-2 h-1, a photocurrent density of -1.05 mA cm-2 and a Faraday efficiency of 79.0% on this photocathode.

Preparation of novel HKUST-1-glucose oxidase composites and their application in biosensing.

Copper-based metal-organic frameworks (MOF) and multi-walled carbon nanotubes (HKUST-1-MWCNTs) composite were synthesized by one-step hydrothermal method, and PDA-enzyme-HKUST-1-MWCNTs composite was prepared by one-pot method for the construction of glucose biosensors, which realized the sensitive amperometric detection of glucose at 0.7 V (vs. SCE). The sensitivity of the sensor for glucose detection was 178 µA mM-1cm-2 in the wide linear range of 0.005 ~ 7.05 mM, the detection limit was 0.12 µM and the corresponding RSD was 3.8%. Its high performance is mainly benefitted from the high porosity and large specific surface area of HKUST-1, the good conductivity of MWCNTs, and the excellent adhesion and dispersion of PDA. The strategy of combining PDA and MWCNTs to improve the dispersion and conductivity of MOF is expected to achieve a wider application of MOF-based materials in the electrochemical biosensing field.

Poly(noradrenalin) based bi-enzyme biosensor for ultrasensitive multi-analyte determination.

In order to realize the multi-analyte assays for physiological molecules and environmental contaminants, a bi-enzyme biosensor based on horseradish peroxidase (HRP)-catalyzed noradrenalin (NA) polymerization in the presence of H2O2 was fabricated for the first time and utilized in immobilizing HRP and glucose oxidase (GOx) simultaneously. The resultant bi-enzyme modified electrode was demonstrated to be efficient in monitoring multi-analyte (H2O2, Cr(III), glucose, and Cr(VI)). It was shown that the prepared PNA-HRP-GOx/Pt electrode exhibits a sensitivity (S) high up to 628.4 µA mM-1 cm-2 in the linear range (LR) of 0.50 µM ~ 0.42 mM and a S of 208.9 µA mM-1 cm-2 in the LR of 0.42 mM~3.5 mM in glucose sensing, with a limit of detection (LOD) of 0.08 µM observed; in Cr(VI) sensing a LOD of 0.20 nM and a LR of 0.50 ~ 6.0 nM were obtained. With the addition of polyaniline (PANI), the resultant PNA-HRP-GOx/PANI/Pt electrode potentiostated at - 0.20 V responded linearly to H2O2 concentration in 0.05 ~ 30.2 mM range, with linearly responses to Cr(III) concentration in the LR of 0.01 ~ 3.8 µM. Hence, amperometric biosensors with high S, low LOD and good anti-interference ability for detection of glucose, H2O2 and heavy metal ions (Cr(III) and Cr(VI)) were developed.

L-tyrosine polymerization-based ultrasensitive multi-analyte enzymatic biosensor.

Novel amperometric bi-enzyme biosensor based on tyrosinase (Tyr)-catalyzed L-tyrosine polymerization to effectively immobilize Tyr and glucose oxidase (GOx) simultaneously has been developed and is demonstrated to be efficient in monitoring multi-analyte (bisphenol A (BPA), phenol, Cr(III), glucose, and Cr(VI)). For the first time, the polymer from L-tyrosine oxidation (PLT) was utilized to in-situ immobilize biomacromolecules and was demonstrated to be effective in entrapping high-load and high-activity enzymes. The prepared bi-enzyme biosensor (PLT-Tyr-GOx/Au electrode) works well in the biosensing of glucose (GOx substrate) and Cr(VI) (GOx inhibitor), and also exhibits excellent performance in Tyr substrates (BPA and phenol) and Tyr inhibitor (Cr(III)) sensing. In addition, the resultant biosensor exhibits excellent stability, precision, high sensitivity and fabrication simplicity, which may find wide applications in diversified fields including biotechnology.