Fabrication of an electrochemical platform based on the self-assembly of graphene oxide-multiwall carbon nanotube nanocomposite and horseradish peroxidase: direct electrochemistry and electrocatalysis.

A novel hybrid nanomaterial (GO-MWNTs) was explored based on the self-assembly of multiwall carbon nanotubes (MWNTs) and graphene oxide (GO). Compared with pristine MWNTs, such a nanocomposite could be well dispersed in aqueous solution and exhibit a negative charge. Driven by the electrostatic interaction, positively charged horseradish peroxidase (HRP) could then be immobilized onto GO-MWNTs at the surface of a glassy carbon (GC) electrode to form a HRP/GO-MWNT/GC electrode under mild conditions. TEM was used to characterize the morphology of the GO-MWNT nanocomposite. UV-vis and FTIR spectra suggested that HRP was immobilized onto the hybrid matrix without denaturation. Furthermore, the immobilized HRP showed enhanced direct electron transfer for the HRP-Fe(III)/Fe(II) redox center. Based on the direct electron transfer of the immobilized HRP, the HRP/GO-MWNT/GC electrode exhibited excellent electrocatalytic behavior to the reduction of H(2)O(2) and NaNO(2), respectively. Therefore, GO-MWNTs could provide a novel and efficient platform for the immobilization and biosensing of redox enzymes, and thus may find wide potential applications in the fabrication of biosensors, biomedical devices, and bioelectronics.

Spectroscopic analyses on interaction of Amantadine-Salicylaldehyde, Amantadine-5-Chloro-Salicylaldehyde and Amantadine-o-Vanillin Schiff-Bases with bovine serum albumin (BSA).

In this work, three Tricyclo [3.3.1.1(3,7)] decane-1-amine (Amantadine) Schiff-Bases, Amantadine-Salicylaldehyde (AS), Amantadine-5-Chloro-Salicylaldehyde (AS-5-C) and Amantadine-o-Vanillin (AS-o-V), were synthesized by direct heating reflux method in ethanol solution and characterized by infrared spectrum and elementary analysis. Fluorescence quenching was used to study the interaction of these Amantadine Schiff-Bases (AS, AS-5-C and AS-o-V) with bovine serum albumin (BSA). According to fluorescence quenching calculations the bimolecular quenching constant (K(q)), apparent quenching constant (K(SV)), effective binding constant (K(A)) and corresponding dissociation constant (K(D)), binding site number (n) and binding distance (r) were obtained. The results show that these Amantadine Schiff-Bases can obviously bind to BSA molecules and the binding strength order is AS

Detection of reactive oxygen species (ROS) generated by TiO2(R), TiO2(R/A) and TiO2(A) under ultrasonic and solar light irradiation and application in degradation of organic dyes.

In the present work, the rutile, anatase and mixed (rutile and anatase) crystal phase TiO(2) powders were irradiated by ultrasound and solar light, respectively, and the generation of reactive oxygen species (ROS) were detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). The DPCO can be extracted by the mixed solvent of benzene and carbon tetrachloride and the extract liquors display an obvious absorption peak around 563nm. In addition, the influences of (ultrasonic or solar light) irradiation time, TiO(2) addition amount and DPCI concentration on the quantities of generated ROS were also reviewed. The kinds of generated ROS were determined by using several radical scavengers. At last, the researches on the sonocatalytic and photocatalytic degradation of several organic dyes were also performed. It is wished that this paper might offer some important subjects for broadening the applications of sonocatalytic and photocatalytic technologies.

Spectroscopic studies on interaction and sonodynamic damage of metallochlorophyllin (Chl-M (M=Fe, Zn and Cu)) to protein under ultrasonic irradiation.

In this paper, the chlorophyll derivatives, metallochlorophyllin (Chl-M) (M=Fe, Zn and Cu) including chlorophyllin iron (Chl-Fe), chlorophyllin zinc (Chl-Zn) and chlorophyllin copper (Chl-Cu), were adopted as sonosensitizers to combine with ultrasonic irradiation, and the sonodynamic damage of bovine serum albumin (BSA) was investigated. At first, the interaction of Chl-M with BSA was studied by fluorescence spectroscopy. The results show that the quenching mechanism belongs to a static process and among them the affinity of Chl-Fe to BSA is the most obvious. Then, some influence factors on the sonodynamic damage of BSA molecules in the presence of Chl-M under ultrasonic irradiation were also studied. Synchronous fluorescence spectra show that the binding and damage sites of Chl-M to BSA molecule are mainly on the tryptophan (Trp) residues. The generation of ROS in Chl-M sonodynamic process is estimated by the method of Oxidation-Extraction Spectrometry (OEP). This paper may offer some valuable references for the study of the sonodynamic activity of Chl-M and the effect of the central metals. Synchronously, it contributes to the application of Chl-M in SDT for tumor treatment.

Oxidation-extraction spectrometry of reactive oxygen species (ROS) generated by chlorophyllin magnesium (Chl-Mg) under ultrasonic irradiation.

In order to examine the mechanism and process of sonodynamic reaction, the chlorophyllin magnesium (Chl-Mg) acting as a sonosensitizer was irradiated by ultrasound, and the generation of reactive oxygen species (ROS) were detected by the method of oxidation-extraction spectrometry (OES). That is, under ultrasonic irradiation in the presence of Chl-Mg, the 1,5-diphenyl carbazide (DPCI) is oxidized by generated ROS into 1,5-diphenyl carbazone (DPCO), which can be extracted by mixed organic solvent and display a obvious visible absorption at 563 nm wavelength. Besides, the generation conditions of ROS were also reviewed. The results demonstrated that the quantities of generated ROS increased with the increase of ultrasonic irradiation time, Chl-Mg concentration and DPCI concentration. Finally, several radical scavengers (l-Histidine (His), 2,6-Di-tert-butyl-methylphenol (BHT) and Vitamin C (VC)) were used to determine the kind of the generated ROS. It was found that at least the hydroxyl radical (OH) and singlet oxygen (1O2) were generated in the presence of Chl-Mg under ultrasonic irradiation. It is wish that this paper might offer some valuable references for the study on the mechanism of SDT and the application of Chl-Mg in tumor treatment.

Sonocatalytic degradation of organic dyes and influence of Al(2)O(3), Y(2)O(3) and Fe(2)O(3) on catalytic activity of TiO(2) under ultrasonic irradiation.

In order to improve the sonocatalytic activity of TiO(2), Al(2)O(3)/TiO(2), Y(2)O(3)/TiO(2) and Fe(2)O(3)/TiO(2) composites were prepared using mechanical mixing, liquid boiling, ultrasonic dispersion and heat-treated methods. And then, a series of degradation experiments were carried out under ultrasonic irradiation. Also, the influences of heat-treated temperature and heat-treated time on the sonocatalytic activity of Al(2)O(3)/TiO(2), Y(2)O(3)/TiO(2) and Fe(2)O(3)/TiO(2), and ultrasonic irradiation time and solution acidity on the sonocatalytic degradation of Acid red B were investigated by UV-vis spectra. It was found that the degradation ratio showed significant increase in the order TiO(2) < Fe(2)O(3)/TiO(2) < Y(2)O(3)/TiO(2) < Al(2)O(3)/TiO(2). And the corresponding percentage degradations are about 37, 45, 52 and 81%, respectively. In addition, for exploring the universality, the degradation of other several organic dyes was also reviewed under the same conditions. Because of good degradation efficiency, this method may be an advisable choice for the treatment of non- or low-transparent wastewaters in the future.

The investigation of sonocatalytic activity of Er3+:YAlO3/TiO2-ZnO composite in azo dyes degradation.

In this work, the emphasis was mainly placed on investigating the sonocatalytic activity of TiO(2)-ZnO mixed with Er(3+):YAlO(3), namely, Er(3+):YAlO(3)/TiO(2)-ZnO composite. It is able to utilize the sonoluminescence light to improve the sonocatalytic degradation of organic dyes. The Er(3+):YAlO(3) as up-conversion luminescence agent was synthesized by sol-gel and auto-combustion method, and then Er(3+):YAlO(3)/TiO(2)-ZnO composite as sonocatalyst were prepared by ultrasonic dispersion and liquids boil method. The prepared up-conversion luminescence agent and composites were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Acid Red B dye was selected to examine the sonocatalytic activity of Er(3+):YAlO(3)/TiO(2)-ZnO composite. The degradation reaction processes were monitored by UV-vis spectrophotometer and ion chromatogram. The influences on the activity of the Er(3+):YAlO(3)/TiO(2)-ZnO such as Ti/Zn molar ratio, heat-treated temperature and heat-treated time were studied. The results showed that the Er(3+):YAlO(3)/TiO(2)-ZnO composite exhibited a significantly high sonocatalytic activity compared with other catalysts in the degradation of Acid Red B. And the sonocatalyst with 1:1 Ti/Zn molar ratio heat-treated at 550°C for 60min showed the highest sonocatalytic activity. At last, the experiment also indicated that it has a good sonocatalytic activity to degrade other organic dyes.

The investigation of the interaction between ribavirin and bovine serum albumin by spectroscopic methods.

The interaction between ribavirin (RIB) with bovine serum albumin (BSA) has been investigated by fluorescence quenching technique in combination with UV-vis absorption and circular dichroism (CD) spectroscopies under the simulative physiological conditions. The quenching of BSA fluorescence by RIB was found to be a result of the formation of RIB-BSA complex. The binding constants and the number of binding sites were calculated at three different temperatures. The values of thermodynamic parameters ∆H, ∆S, ∆G at different temperatures indicate that hydrophobic and hydrogen bonds played important roles for RIB-BSA association. The binding distance r was obtained according to the theory of Förster's non-radiation energy transfer. The displacement experiments was performed for identifying the location of the binding site of RIB on BSA. The effects of common ions on the binding constant of RIB and BSA were also examined. Finally, the conformational changes of BSA in the presence of RIB were also analyzed by CD spectra and Synchronous fluorescence spectra.

Sorption characteristics and separation of tellurium ions from aqueous solutions using nano-TiO2.

Titanium dioxide nanoparticles (nano-TiO(2)) were employed for the sorption of Te(IV) ions from aqueous solution. A detailed study of the process was performed by varying the sorption time, pH, and temperature. The sorption was found to be fast, equilibrium was reached within 8 min. When the concentration of Te(IV) was below 40 mg L(-1), at least 97% of tellurium was adsorbed by nano-TiO(2) in the pH range of 1-2 and 8-9. The sorbed Te(IV) ions were desorbed with 2.0 mL of 0.5 mol L(-1) NaOH. The sorption data could be well interpreted by the Langmuir model with the maximum adsorption capacity of 32.75 mg g(-1) (20 ± 0.1 °C) of Te(IV) on nano-TiO(2). The kinetics and thermodynamics of the sorption of Te(IV) onto nano-TiO(2) were also studied. The kinetic experimental data properly correlated with the second-order kinetic model (k(2)=0.0368 g mg(-1)min(-1), 293 K). The overall rate process appeared to be influenced by both boundary layer diffusion and intra-particle diffusion. The mean energy of adsorption was calculated to be 17.41 kJ mol(-1) from the Dubinin-Radushkevich (D-R) adsorption isotherm at room temperature. Moreover, the thermodynamic parameters for the sorption were estimated, and the ΔH(0) and ΔG(0) values indicated the exothermic and spontaneous nature of the sorption process, respectively. Finally, Nano-TiO(2) as sorbent was successfully applied to the separation of Te(IV) from the environmental samples with satisfactory results (recoveries >95%, relative standard deviations was 2.0%).

Degradation of malachite green solution using combined microwave and ZnFe(2)O(4) powder.

Dyestuff malachite green MG in aqueous solution can be degraded rapidly assisted by microwave irradiation (MW) in the presence of ZnFe(2)O(4) powder. ZnFe(2)O(4) acted as a MW as well as the catalyst for MG degradation, and could be used repeatedly. The effects of MW time, initial concentration of MG, addition amount, pH value and used times of ZnFe(2)O(4) powder were discussed in details using UV-Vis spectra, FT-IR spectra, ion chromatography and TOC analysis technologies. The results showed that the degradation percentage of MG was nearly 100%, corresponding to 92% of TOC removal, when the mass fraction of ZnFe(2)O(4) was 1.2%, MW 500 W and the irradiation time 2 min. Additionally, the above method using ZnFe(2)O(4) powder as catalyst combined with MW has high degradation ratios, short reaction time, low costs, no intermediates and no secondary pollution. Therefore, it may be available for the treatment of various dyestuff wastewaters on a large scale.

[Comparison of ICP-MS and two other analytical methods for determination of selenium content in Cordyceps militaris].

Samples were digested by microwave digestion. The selenium content in selenium enriched Cordyceps militaris was determined by ICP-MS method, HPLC/fluorometric method, and 3,3-diaminobenzidine method separately. And the detection conditions, the lowest detection limit and the relative standard deviation (RSD) of the three determination methods were compared. The detection conditions of the three methods for the detection of selenium content in selenium enriched Cordyceps militaris were established. It was showed that the lowest detection limit of ICP-MS method, HPLC/fluorometric method, and 3,3-diaminobenzidine method was 0.260 7, 0.182 1 and 10.485 9 microg x L(-1) respectively, and this means that the lowest detection limit of ICP-MS method was the lowest and that of 3,3-diaminobenzidine method was the highest. For the same sample the relative standard deviation (RSD) of ICP-MS method was the lowest and the RSD of 3,3-diaminobenzidine method was the highest. It was recommended that selenium content is determined by ICP-MS and HPLC/fluorometric method when the selenium in the sample is very low and by 3,3-diaminobenzidine method when the content is rather high.

Sonocatalytic degradation of some dyestuffs and comparison of catalytic activities of nano-sized TiO2, nano-sized ZnO and composite TiO2/ZnO powders under ultrasonic irradiation.

Here, a novel sonocatalyst, composite TiO2/ZnO powder, was prepared through the combination of nano-sized TiO2 and ZnO powders. Because of the appropriate adsorbability to organic pollutants and special crystal interphase between TiO2 and ZnO particles, the composite TiO2/ZnO powder exhibits a high sonocatalytic activity under ultrasonic irradiation during the degradation of acid red B. Especially, the sonocatalytic activity of composite TiO2/ZnO powder with 4:1 molar proportion treated at 500 degrees C for 50 min showed obvious improvement compared with pure nano-sized TiO2 and ZnO powders. When the experimental conditions such as 10mg/L acid red B concentration, 1.0 g/L catalyst addition amount, pH=7.0, 20 degrees C system temperature, 100 min ultrasonic time and 50 mL total volume were adopted, the satisfactory degradation ratio and rate were obtained. All experiments indicate that the sonocatalytic method using composite TiO2/ZnO powder may be a more advisable choice for the treatments of non- or low-transparent organic wastewaters in future.

[Study of autofluorescence spectra of protoporphyrin IX in human serum].

The fluorescence spectra of protoporphyrin IX (PPIX) solutions and human serum samples were measured and analyzed under physiological conditions. The experimental results showed that the fluorescence of PPIX in human serum was mainly derived from PPIX-serum albumin complex. Moreover, the effects of serum albumin and PPIX on the PPIX emission fluorescence were also investigated. Compared with pure PPIX solution, not only a red-shift of PPIX fluorescence peak was found for PPIX+albumin solution, but also albumin had a fluorescence enhancement effect on protoporphyrin IX. For the mixture of PPIX+albumin, with the increase of PPIX the wavelength of the PPIX emission peak will increased a little when its concentration was less than 0.8 x 10(-5) mol x L(-1), but was nearly invariable when its concentration was more than 0.8 x 10(-5) mol x L(-1).

[Preparation of nanometer TiO2 doped with upconversion luminescence agent and investigation on degradation of ethyl violet using visible light].

A novel upconversion luminescence agent 40CdF2 x 60BaF2 x 1.6Er2O3 was synthesized and the fluorescent spectrum was determined. This upconversion luminescence agent can emit five upconversion fluorescent peaks whose wavelengths are all below 387nm under the excitation of 488 nm visible light. This upconversion luminescence agent was mixed into nanometer TiO2 powder by ultrasonic dispersion and the doped nanometer TiO2 photocatalyst utilizing visible light was prepared. The doped TiO2 powder was charactered by XRD and TEM and its photocatalytic activity was checked through the photocatalytic degradation of ethyl violet dye as a model compound under the visible light irradiation emitted by three basic color lamp. Otherwise, in order to compare the photocatalytic activities the same experiment was carried out for undoped photocatalytic TiO2 powder. The degradation ratio of ethyl violet dye in the presence of doped nanometer TiO2 powder reached 99.68% under visible light irradiation at 12.0 h which was obviously higher than the corresponding degradation ratio in the presence of undoped nanometer TiO2 powder, which indicate that the upconversion luminescence agent prepared as dopant can effectively turn visible lights to ultraviolet lights which are absorbed by nanometer TiO2 particles and produce the electron-cavity pairs.

Investigation on photocatalytic degradation of ethyl violet dyestuff using visible light in the presence of ordinary rutile TiO2 catalyst doped with upconversion luminescence agent.

To use solar irradiation or interior lighting efficiently, a new photocatalyst with high catalytic activity in visible light was sought. In this work, an upconversion luminescence agent, 40 CdF(2).60 BaF(2).1.0 Er(2)O(3), was synthesized and its fluorescent spectrum was determined. It is found that this upconversion luminescence agent can emit five upconversion fluorescent peaks below 387nm under the excitation of 488nm visible light. The upconversion luminescence agent has revealed an improvement over ordinary titanium dioxide (TiO(2)) in photocatalytic activity under visible light irradiation for the photocatalytic degradation of ethyl violet in aqueous solution as a model compound. The TiO(2) photocatalyst doped with upconversion luminescence agent was characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The photocatalytic degradation of ethyl violet was tracked by UV-vis and (1)H-NMR spectra, and the influences of irradiation time, initial concentration of ethyl violet, addition amount of TiO(2) catalyst and initial pH value were also investigated. To affirm the complete mineralization, the total organic carbon (TOC) was also tested. The degradation rate of ethyl violet in the presence of doped rutile TiO(2) photocatalyst reached 87.08% at 4.0h visible light irradiation, which was obviously higher than the corresponding degradation rate (35.42%) in the presence of undoped rutile TiO(2) powder. The research results show that the upconversion luminescence agent is necessary to transform visible lights into ultraviolet lights and thus make the best use of visible lights. By calculation, the upconversion efficiency of the emission peak at 380nm was estimated to be about 0.78%. The TiO(2) powder doped upconversion luminescence agent under visible light irradiation is able to decompose the ethyl violet in aqueous solution efficiently, therefore, this method may be envisaged as a technology for treating dyes wastewaters using solar energy, especially at textile industries in developing countries.

Sonocatalytic degradation of methyl parathion in the presence of nanometer and ordinary anatase titanium dioxide catalysts and comparison of their sonocatalytic abilities.

The degradation of methyl parathion (O,O-dimethyl-O-(4-nitrophenyl)-phosphorothioate) using anatase titanium dioxide (TiO(2)) powder as heterogeneous sonocatalysts is reported. The influences of reaction parameters such as the species of TiO(2) sonocatalysts, methyl parathion concentrations, TiO(2) adding amount, pH, ultrasonic intensity, ultrasonic frequency and temperature have been investigated and the optimal conditions for eliminating methyl parathion have been identified. The efficiencies of sonocatalytic degradation in both nanometer and ordinary anatase systems are compared and the results indicate that the sonocatalytic activity of nanometer anatase TiO(2) powder is better than that of ordinary anatase TiO(2) powder. The primary degradation and the total mineralization of methyl parathion have been monitored by high performance liquid chromatography (HPLC) and UV-vis spectra, respectively. Methyl parathion got destroyed to some extent in both nanometer and ordinary anatase systems under ultrasonic irradiation. The kinetics for the degradation process of methyl parathion follows the first-order reaction. The degradation ratio of methyl parathion surpassed 90% within 50min in the optimal experiment conditions.

Degradation of dyestuff wastewater using visible light in the presence of a novel nano TiO2 catalyst doped with upconversion luminescence agent.

A new upconversion luminescence agent, 40CdF2 x 60BaF2 x 0.8Er2O3, was synthesized and its fluorescent spectra were determined. This upconversion luminescence agent can emit five upconversion fluorescent peaks shown in the fluorescent spectra whose wavelengths are all below 387 nm under the excitation of 488 nm visible light. This upconversion luminescence agent was mixed into nano rutile TiO2 powder by ultrasonic and boiling dispersion and the novel doped nano TiO2 photocatalyst utilizing visible light was firstly prepared. The doped TiO2 powder was charactered by XRD and TEM and its photocatalytic activity was tested through the photocatalytic degradation of methyl orange as a model compound under the visible light irradiation emitted by six three basic color lamps. In order to compare the photocatalytic activities, the same experiment was carried out for undoped TiO2 powder. The degradation ratio of methyl orange in the presence of doped nano TiO2 powder reached 32.5% under visible light irradiation at 20 h which was obviously higher than the corresponding 1.64% in the presence of undoped nano TiO2 powder, which indicate the upconversion luminescence agent prepared as dopant can effectively turn visible lights to ultraviolet lights that are absorbed by nano TiO2 particles to produce the electron-cavity pairs. All the results show that the nano rutile TiO2 powder doped with upconversion luminescence agent is a promising photocatalyst using sunlight for treating the industry dye wastewater in great force.