摘要：
A neutralization hydrolysis route has been used to synthesize titanium oxide nanoparticles. Transmission electron microscopy(TEM) and X-ray diffraction(XRD) characterization results showed the TiO(2) nanoparticles were single anatase phases when calcined at 600 degrees C-800 degrees C for 2h. The particle diameter ranged from 15 to 30nm. The pH value was key factor for precursor composition. When pH value 2-4, the H(2)TiO(3) precursor with low agglomeration was obtained. As-prepared anatase TiO2 nanoparticles, during photodegradation of methylic orange under UV-light irradiation(lambda=254nm), exhibited excellent activity, more than 95.5% methylic orange was degraded in 1h.
摘要：
A novel strategy for fabricating horseradish peroxidase (HRP)-based H2O2 sensor has been developed by combining the merits of carbon sol–gel supporting matrix and nano-scaled particulate gold (nano-Au) mediator. The thiol functional group-derived carbon ceramic electrode (CCE) was first constructed using (3-mercaptopropyl) trimethoxy silane as sol–gel monomer. Then, the stable nano-Au monolayer was obtained through covalent linkage between nano-Au and thiol group on the surface of CCE. The experimental results showed that nano-Au monolayer formed not only could steadily immobilize HRP but also efficiently retain its bioactivity. Hydrogen peroxide was detected with the aid of hydroquinone mediator to transfer electrons between the electrode and HRP. The process parameters for the fabrication of the enzyme electrode and various experimental variables such as the operating potential, mediator concentration and pH of background electrolyte were explored for optimum analytical performance of the enzyme electrode. The biosensor had a fast response of less than 8 s with linear range of 1.22×10−5 to 1.10×10−3mol l−1 and a detection limit of 6.1×10−6mol l−1. The sensitivity of the sensor for H2O2 was 0.29 A l mol−1 cm−2. The activation energy for enzyme reaction was calculated to be 10.1 kJ mol−1. The enzyme electrode retained 75% of its initial activity after 5 weeks storage in phosphate buffer at pH 7.
摘要：
A highly selective and sensitive electrochemical sensor modified with carboxymethylated, beta-cyclodextrin (CM-beta-CDP) polymer film was fabricated for the determination of dopamine (DA) in the presence of ascorbic acid (AA). The electrochemical behavior of DA and AA at the chemically modified electrode was investigated by cyclic voltammetry (CV) and differential pulse voltammetry. The response mechanism of CM-beta-CDP film for DA was based on the combination of electrostatic and inclusion interaction of CM-beta-CDP for DA, which was distinguished from the response mechanism of the charged polymer film modified electrode that only relied upon the electrostatic interaction between charged polymer film and DA (or AA) to realize the separation of overlapping peak potential of DA and AA. The CM-beta-CDP film showed preferable analytical performance characteristics in catalytic oxidation of DA compared with the beta-CDP polymer film. Under optimized conditions, it was feasible for the electrode modified with the CM-beta-CDP film to selectively determine DA in the presence of a large excess of AA. A linear calibration plot was obtained over the range 0.8-60 muM with a sensitivity of 65 nA/muM and a detection limit (signal/noise (S/N) = 3) of 0.2 muM in the presence of 1.0mM AA. This electrochemical sensor showed excellent sensitivity, repeatability, stability, and recovery for the determination of DA. The interference of AA with the determination of DA could be efficiently eliminated.
摘要：
A novel approach to assemble an H2O2 amperometric biosensor was introduced. The biosensor was constructed by entrapping horseradish peroxidase (HRP) labeled nano‐scaled particulate gold (nano‐Au) (HRP‐nano‐Au electrostatic composite) in a new silica sol‐gel/alginate hybrid film using glassy carbon electrode as based electrode. This suggested strategy fully merged the merits of sol‐gel derived inorganic‐organic composite film and the nano‐Au intermediator. The silica sol‐gel/alginate hybrid material can improve the properties of conventional sol‐gel material and effectively prevent cracking of film. The entrapment of HRP in the form of HRP‐nano‐Au can not only factually prevent the leaking of enzyme out of the film but also provide a favorable microenvironment for HRP. With hydroquinone as an electron mediator, the proposed HRP electrode exhibited good catalytic activity for the reduction of H2O2. The parameters affecting both the qualities of sol‐gel/alginate hybrid film and the biosensor response were optimized. The biosensor exhibited high sensitivity of 0.40 Al mol−1 cm−2 for H2O2 over a wide linear range of concentration from 1.22×10−5 to 1.46×10−3 mol L−1, rapid response of <5 s and a detection limit of 0.61×10−6 mol L−1. The enzyme electrode has remarkable stability and retained 86% of its initial activity after 45 days of storage in 0.1 mol L−1 Tris‐HCl buffer solutions at pH 7.
摘要：
A new enzyme-based amperometric biosensor for hydrogen peroxide was developed relying on the efficient immobilization of horseradish peroxidase (HRP) to a nano-scaled particulate gold (nano-Au) film modified glassy carbon electrode (GC). The nano-Au film was obtained by a chitosan film which was first formed on the surface of GC. The high affinity of chitosan for nano-Au associated with its amino groups resulted in the formation of nano-Au film on the surface of GC. The film formed served as an intermediator to retain high efficient and stable immobilization of the enzyme. H2O2,was detected using hydroquinone as an electron mediator to transfer electrons between the electrode and HRP. The HRP immobilized on nano-Au film maintained excellent electrocatalytical activity to the reduction of H2O2. The experimental parameters such as the operating potential of the working electrode, mediator concentration and pH of background electrolyte were optimized for best analytical performance of amperometry. The linear range of detection for H2O2 is from 6.1 x 10(-6) to 1.8 x 10(-3) mol L-1 with a detection limit of 6.1 mumol L-1 based on signal/noise = 3. The proposed HRP enzyme sensor has the features of high sensitivity (0.25 Almol(-1)cm(-2)), fast response time (t(90%) less than or equal to 10 s) and a long-term stability (> 1 month). As an extension, glucose oxidase (GOD) was chemically bound to HRP-modified electrode. A GOD/HRP bienzyme-modified electrode formed in this way can be applied to the determination of glucose with satisfactory performance.
通讯机构：
[Lei, Cunxi] H;Hunan City Univ, Coll Chem & Environm Engn, Yiyang 413000, Peoples R China.
摘要：
A graphene (GN) and ionic liquid (IL) modified selenium-doped carbon paste electrode (GN/IL/Se/CPE) was established to simultaneously determine trace Cu(II) and Sb(III) by differential pulse voltammetry (DPV). Several parameters which affect the stripping current response were investigated and optimized, including the proportion of Se powder, concentration of hydrochloric acid, deposition time and deposition potential. The DPV curves were recorded by simultaneous deposition of Cu(II) and Sb(III) at −0.4 V for 50 s in a supporting electrolyte solution HCl of 0.30 mol L−1. Under the optimized conditions, the GN/IL/Se/CPE sensor has a good linear response in the range of 2.0 × 10−6 to 7.0 × 10−5 mol L−1 for Cu(II) and 2.0 × 10−6 to 4.0 × 10−5 mol L−1 for Sb(III). The detection limits were 6.6 × 10−7 mol L−1 for Cu(II) and 4.3 × 10−7 mol L−1 for Sb(III). The sensor showed favorable stability and higher sensitivity. The present work extends the scope of these devices as mercury-free sensors and can be used to detect Cu(II) and Sb(III) simultaneously.
