Construction of a novel electrochemical biosensor based on a mesoporous silica/oriented graphene oxide planar electrode for detecting hydrogen peroxide.

A constant magnetic field (CMF) was used to arrange the orientation of graphene oxide (GO) which was modified on a self-made screen-printed electrode. We evaluated the efficiency of this method for potential analytical application towards the sensing of hydrogen peroxide (H2O2). Mesoporous silica (MS)-encapsulated horseradish peroxidase (HRP) was immobilized on the electrode with vertically arranged GO to construct an H2O2 sensor (denoted as CMF/GO/HRP@MS). The linear range of the response of the CMF/GO/HRP@MS sensor to H2O2 was 0.1-235 µM, and the detection limit was as low as 0.01 µM. The results demonstrated that the vertical arrangement of GO resulting from the CMF on the electrode surface could increase the electron transfer rate. The excellent selectivity and anti-interference ability of this sensor to H2O2 in physiological samples may be attributed to the synergistic effect of mesoporous silica, GO and constant magnetic field.

Perovskite LaTiO3-Ag0.2 nanomaterials for nonenzymatic glucose sensor with high performance.

In this paper, a nonenzymatic glucose biosensor based on perovskite LaTiO3-Ag0.2(LTA) modified electrode was presented. The morphology and the composition of the perovskite LaTiO3-Ag0.2 nanomaterials were characterized by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively. The LaTiO3-Ag0.2(LTA) composite was investigated by electrochemical characterization using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimal conditions, CV and chronoamperometry (I-t) study revealed that, compared with the bare glassy carbon electrode (GCE), the modified electrode showed a remarkable increase in the efficiency of the electrocatalytic oxidation of glucose, starting at around +0.70 V (vs. Ag/AgCl). The prepared sensor exhibited a high sensitivity of 784.14 µAmM⁻¹ cm⁻², a low detection limit of 2.1×10⁻7 M and a wide linear range from 2.5 µM to 4 mM (R=0.9997). More importantly, the LTA modified electrode was also relatively insensitive to commonly interfering species such as ascorbic acid (AA), uric acid (UA), dopamine (DA) in high potential. Moreover, the nonenzymatic sensor was applied to the determination of glucose in human serum samples and the results were in good agreement with clinical data. Electrodes modified with perovskite nanomaterials are highly promising for nonenzymatic electrochemical detection of glucose because of their high sensitivity, fast response, excellent stability and good reproducibility.

(E)-5-(3,5-Dimethyl-phen-yl)-N-[4-(methyl-sulfan-yl)benzyl-idene]-1,3,4-thia-diazol-2-amine.

The title compound, C(18)H(17)N(3)S(2), was synthesized by the reaction of 5-(3,5-dimethyl-phen-yl)-1,3,4-thia-diazol-2-amine and 4-(methyl-sulfan-yl)benzaldehyde. An intra-molecular C-H⋯S hydrogen bond results in the formation of a planar (r.m.s. deviation = 0.003 Å) five-membered ring. In the crystal structure, inter-molecular C-H⋯N hydrogen bonds link the mol-ecules to form layers parallel to (011).

(S)-Ethyl 2-[4-(6-chloro-quinoxalin-2-yl-oxy)phen-oxy]propanoate.

In the mol-ecule of the title compound, C(19)H(17)ClN(2)O(4), the quinoxaline ring system is planar [maximum deviation = 0.013 (3) Å] and oriented at a dihedral angle of 80.18 (3)° with respect to the benzene ring. In the crystal structure, inter-molecular C-H⋯N inter-actions link mol-ecules into chains. π-π contacts between the quinoxaline systems [centroid-centroid distance = 3.654 (1) Å] may further stabilize the structure.

2-Nitro-N-propyl-benzamide.

The title compound, C(10)H(12)N(2)O(3), contains three mol-ecules in the asymmetric unit. In the crystal structure, inter-molecular N-H⋯O inter-actions link the mol-ecules into chains along the b axis. The crystal structure is consolidated by weak C-H⋯π inter-actions.

6,10,16,19-Tetra-oxatrispiro-[4.2.2.4.2.2]nona-deca-ne.

The asymmetric unit of the title compound, C(15)H(24)O(4), contains one half-mol-ecule; a twofold rotation axis passes through the central C atom. The non-planar six- and five-membered rings adopt chair and envelope conformations, respectively. In the crystal structure, inter-molecular C-H⋯O hydrogen bonds link the mol-ecules.