Surface functionalization of SBA-15 nanorods for anticancer drug delivery

SBA-15 nanorods with high surface area (1010 m² g⁻¹) were functionalized by post grafting method with three different alkoxysilanes including (3-aminopropyl) triethoxysilane (APTES), 3-[bis(2-hydroxyethyl)amino] propyl triethoxysilane (HAPS) and 3-[2-(2-aminoethylamino) ethylamino] propyl trimethoxysilane (AEPS). The prepared materials were used as nanocarriers for an anticancer drug (gemcitabine). The obtained samples were characterized by SAXS, elemental analysis, TGA, N₂ adsorption/desorption, SEM, TEM, FTIR and UV spectroscopies. The adsorption and release properties of all samples were investigated. It was found that the surface functionalization increases the interaction between the carrier and gemcitabine and results in the loading enhancement of the drug. In addition, the adsorption of gemcitabine on the modified mesoporous matrix depends on the type and the amount of alkoxysilanes groups. The maximum content of the deposited drug in the modified SBA-15 nanorods is close to 22 wt.%. The rate of the drug release from the modified samples containing NH₂ groups on their surfaces is pH dependent.     

Surface enhanced fluorescence of anti-tumoral drug emodin adsorbed on silver nanoparticles and loaded on porous silicon

Fluorescence spectra of anti-tumoral drug emodin loaded on nanostructured porous silicon have been recorded. The use of colloidal nanoparticles allowed embedding of the drug without previous porous silicon functionalization and leads to the observation of an enhancement of fluorescence of the drug. Mean pore size of porous silicon matrices was 60 nm, while silver nanoparticles mean diameter was 50 nm. Atmospheric and vacuum conditions at room temperature were used to infiltrate emodin-silver nanoparticles complexes into porous silicon matrices. The drug was loaded after adsorption on metal surface, alone, and bound to bovine serum albumin. Methanol and water were used as solvents. Spectra with 1 μm spatial resolution of cross-section of porous silicon layers were recorded to observe the penetration of the drug. A maximum fluorescence enhancement factor of 24 was obtained when protein was loaded bound to albumin, and atmospheric conditions of inclusion were used. A better penetration was obtained using methanol as solvent when comparing with water. Complexes of emodin remain loaded for 30 days after preparation without an apparent degradation of the drug, although a decrease in the enhancement factor is observed. The study reported here constitutes the basis for designing a new drug delivery system with future applications in medicine and pharmacy.     

pH/redox/thermo-stimulative nanogels with enhanced thermosensitivity via incorporation of cationic and anionic components for anticancer drug delivery

To explore the potential biomedical applications of nanogels, it is a key factor to improve their thermosensitivity. In this paper, triple-responsive nanogels poly(N-isopropylacrylamide–N,N′-dimethylaminoethyl methacrylate–acrylic acid) (PNDA) were synthesized via in situ incorporating both cationic components and anionic components into a normal thermosensitive polymer matrix. The triple-monomer constructed PNDA nanogels displayed an enhanced thermosensitivity as compared with dual-monomer constructed PND nanogels. The PNDA nanogels presented higher encapsulation efficiency (～89%) and exhibited better pH/redox/thermo-responsivenesses in an anticancer drug delivery. In vitro biological study indicated that the PNDA nanogels have excellent biocompatibility and improved anticancer cytotoxicity to A549 cells after loading drug DOX.     

A study of the electrochemical behaviour of electrodes in operating solid-state supercapacitors

The electrochemical behaviour of electrodes and of complete solid-state supercapacitors has been studied by cyclic voltammetry (CV) and galvanostatic charge/discharge (CD) measurements using two independent electrochemical equipments. The first one controlled the execution of the test and recorded the voltage and current values of the complete supercapacitor while the other one recorded the potential changes of the single electrodes. In this work, two different types of capacitors were studied: (a) a symmetric supercapacitor using carbon electrodes, and (b) a hybrid (asymmetric) supercapacitor with ruthenium oxide/carbon in the positive electrode and carbon in the negative electrode. The studies evidenced that in the symmetric capacitors the positive electrode controlled the capacitive performance and an optimal mass ratio from 1.2:1 to 1.3:1 between the positive and the negative electrodes was found in the investigated conditions. For the hybrid supercapacitor it was observed that the ruthenium-based positive electrode influenced the capacitive performance of carbon-based negative electrode and that an accurate balance of carbon loading in the negative electrode was necessary.     

Influence of electrochemical potential on the tribocorrosion behaviour of high carbon CoCrMo biomedical alloy in simulated body fluids by electrochemical impedance spectroscopy

The corrosion and tribocorrosion behaviour of a high carbon CoCrMo alloy sliding against alumina in simulated body fluids under potentiostatic conditions was investigated. The electrochemical behaviour of the sample in two electrolytes at different potentials (−1 V_Ag/AgCl, −0.5 V_Ag/AgCl, +0.05 V_Ag/AgCl, +0.5 V_Ag/AgCl and +0.75 V_Ag/AgCl) was studied by means of electrochemical impedance spectroscopy (EIS). The effects of solution chemistry and applied potential on the wear volume and anodic current were determined. Result shows that wear of CoCrMo alloy is negligible under cathodic and in the cathodic-anodic transition and considerably increases in the passive domain. Third body behaviour depends on surface chemistry which also varied depending on solution chemistry and electrochemically applied potential thus, modifies the tribocorrosion rate of CoCrMo alloy.     

An electrochemical impedance spectroscopy and scanning electron microscopy study of the influence of positive plate compression on the electrochemical behaviour of lead-acid batteries

This study has developed an electrochemical impedance spectroscopy (EIS) method for the in situ investigation of the influence of positive plate compression on the electrochemical behaviour of lead-acid batteries during charge/discharge cycling. The EIS data for a fully charged and fully discharged battery are internally consistent with the expected kinetics of a battery in the opposite states of charge, and demonstrate that EIS measurements may be recorded with a high level of reproducibility. Furthermore, this study has necessitated the development of a special cell incorporating horizontally orientated battery plates that can be subjected to elevated pressure through the stacking of lead bricks on top of the cell, as well as a physically robust reference electrode system that can withstand the application of pressure. For this purpose, a platinum-wire pseudo-reference electrode has been developed, and has been shown to exhibit sufficient electrode stability over the period of an EIS recording, enabling the measurement of reproducible and meaningful EIS data. Additionally, the influence of positive plate compression on the behaviour of the lead-acid battery has been investigated by using scanning electron microscopy (SEM). Clearly, the experimental data show that plate compression enhances significantly the kinetics and concomitant performance of the lead-acid battery, and this is related to the enhanced reactivity of the active material, as rationalized by using the agglomeration-of-spheres (AOS) model.     

Study of the hypophosphite effect on the electrochemical reduction of nitrobenzene on Ni

The effect of the hypophosphite ion on the electrochemical reduction of nitrobenzene on Ni was evaluated from a cyclic voltammetric study and from constant potential electrolysis in an aqueous-ethanol alkaline medium. The results were compared with the data obtained in an hypophosphite-free solution. It was found that in an hypophosphite containing solution an unusual selective reduction of nitrobenzene to nitrosobenzene occurs. It is the first time that nitrosobenzene is detected as the reaction product of the nitrobenzene electrochemical reduction in an aqueous-ethanol solution. It is proposed that the Ni modified surface which is formed upon hypophosphite oxidation is responsible for the non reducibility of nitrosobenzene. The effect of the electrode potential on the nitrobenzene electrolysis on a Ni modified electrode was analysed. It was concluded that the highest nitrosobenzene yield (33%) and selectivity (82%) is achieved at −1.1 V. It was also found that the formation of nitrosobenzene leads to an electrode poisoning effect in the electrolysis process.     

Study on electrochemical behaviour of zinc in dimethylsulphoxide

The kinetics of cathodic deposition and anodic dissolution of zinc in Zn(BF₄)₂ and Zn(ClO₄)₂ solutions in DMSO has been examined using various experimental techniques. It has been found that magnitudes of kinetic parameters of Zn/Zn²⁺---DMSO systems are very close to the values measured in aqueous solutions of these salts. Cathodic efficiency of Zn attains a value of 95%. However, zinc coat contains impurities mainly as incorporated DMSO molecules, which is a conclusion based on X-ray analysis of Zn deposit.     

The corrosion and electrochemical behaviour of pure aluminium in alkaline methanol solutions

The corrosion and electrochemical behaviour of pure aluminium in alkaline methanol solutions has been investigated. The results of hydrogen collection experiments showed that aluminium has a lower corrosion rate in alkaline methanol solutions compared to water based solutions and that the corrosion rate increases with increasing water content of the solution. Polarization and galvanostatic discharge experiments showed that there is a wide potential window of electrochemical activity and a better discharge performance in the alkaline methanol solutions with a certain amount of water. Scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX) showed that the passivation in the later stages of discharge in alkaline methanol solutions at relatively high current densities is due to the formation of a dense Al(OH)₃ layer on the surface of the anode.     

一种复方中草药提取液的护肤功效研究

采用体外实验和人体实验相结合方法,对5种中草药为原料制成的复方提取液进行美白、抗衰老、抗敏舒缓功效研究,并对其刺激性进行评价。结果表明,复方提取液的刺激性分级为无刺激性,具有较强的抑制酪氨酸酶活性、清除DPPH/羟基/超氧阴离子自由基及抑制透明质酸酶活性的能力;使用含复方提取液的乳液4周后,能显著减少皮肤黑色素含量和降低皮肤紫外斑、黄褐斑、皱纹、纹理分值;此外,含复方提取液的乳液能够降低乳酸刺痛程度。上述结果说明该复方中草药提取液使用安全性高,具有较好的美白、抗衰老、抗敏舒缓功效。     

Influencing parameters in the electrochemical anodization of TiO2 nanotubes: Systematic review and meta-analysis

Comprehensive control of processing techniques is primordial when fine-tuning the morphological features of titanium dioxide nanotube arrays (TNTs). This systematic review and meta-analysis compiled articles published from 2007 to date on the synthesis and growth mechanism of nanotubes fabricated via electrochemical anodization and evaluated the potential relationships between anodizing conditions and the resulting structures. Studies were gathered from the Science Direct online database, screened according to predefined criteria, and evaluated for their eligibility. Ninety-nine studies were assessed in the meta-analysis, 87 of them on tube length, 80 on tube diameter, and 33 on wall thickness. Multiple linear regression was performed to test if anodization parameters significantly predicted the resulting morphology of TiO₂ nanotubular structures. Overall regression for the three responses was statistically significant (length: R² = 0.487, p < 0.001; diameter: R² = 0.899, p < 0.001; wall thickness: R² = 0.792, p < 0.001). Applied potential was one of the main effects predicting all three responses (p < 0.001 in every model). Other important main predictors were anodizing time for tube length (p < 0.001), water percentage for tube diameter (p < 0.001) and ammonium fluoride (NH₄F) concentration for wall thickness (p < 0.001).     

Electro-oxidation and determination of gemcitabine hydrochloride,an anticancer drug at gold electrode

Electrochemical behavior of an anticancer drug, gemcitabine hydrochloride (GMB) was studied in 10.4 pH with 0.2 M phosphate buffer solution as supporting electrolyte at 25 ± 0.1 °C at gold electrode (GE) using different voltammetric techniques. The electrochemical process was observed to be diffusion controlled, irreversible and involving one-electron oxidation. Under optimal conditions, the peak current was proportional to GMB concentration in the range of 0.1–15 μM with a detection limit of 0.06 μM by differential pulse voltammetry. The method was developed for the determination of GMB in pharmaceutical formulations and urine as a real sample.     

Effect of electrochemical conditions on the performance worsening of Si/C composite anodes for lithium batteries

An effective and practical method for producing Si/C composites with 10-15 wt% of silicon nanoparticles embedded in a carbon matrix is developed. The procedure consists of mechanically mixing Si with pitch followed by dispersing in toluene and final heat-treatment between 1000 and 1100 °C. The homogeneity of the materials was confirmed by optical microscopy and HRTEM. X-ray photoelectron spectroscopy, X-ray diffraction and N₂ adsorption at 77 K were applied for determining the structural and textural characteristics. The lithium insertion/deinsertion performance was monitored from the galvanostatic charge-discharge characteristics using a Si/C-lithium two-electrode cell, and varying the electrochemical parameters. Silicon essentially enhances the electrode capacity (C_rev up to 600 mAh/g for 15% Si), the effect being proportional to the component content, but it affects the cycle life. The first cycle reversible capacity increases with the decrease of current density and discharge cut-off potential. However, using such conditions during cycling leads to rapid saturation of the silicon particles, from which the decay of the electrochemical performance starts. It is demonstrated that the evolution of reversible and irreversible capacity is strongly dependent on the kinetics of lithium diffusion in silicon particles and on the discharge potential cut-off.     

中药制剂中地西泮的LC/MS/MS分析方法研究

采用液相色谱串联质谱联用仪分析中药制剂中的地西泮.用乙腈-0.01mol/L乙酸铵水溶液(6 4)超声提取试样中的地西泮,离心分离,取上清液过滤膜后用LC/MS/MS进行检测.通过对提取方式和液相色谱分离条件的优化,建立了中药制剂中地西泮的LC/MS/MS检测方法.样品加标的回收率为87.6%～96.8%,相对标准偏差为3.1%～9.6%,多反应监测(选择离子对286.0/194.2及286.0/223.1)检出限为0.5ug/L.     

Electrodeposition of CdS from acidic aqueous thiosulfate solution—Invesitigation of the mechanism by electrochemical quartz microbalance technique

Electrochemical quartz crystal microbalance was used to study mechanism of cathodic electrodeposition of CdS from acidic aqueous solutions containing 0.01 M Cd(ClO₄)₂ and 0.1 M Na₂S₂O₃ as a source of sulfur. Experiments were performed by means of cyclic voltammetry and potentiostatic method. A comparison of gravimetric and current responses at pH 3 and 4 allowed for determination of the potential range in which side reactions of reduction of SO₃²⁻ and H⁺ ions compete most strongly with formation of CdS. The film thickness was determined by means of two methods: from AFM profiles and EQCM measurements.     

Electrochemical behaviour of PANi/polyurethane antifouling coating in salt water studied by electrochemical impedance spectroscopy

Electrochemical behaviour of polyaniline–polyurethane (PANi–PU) antifouling coating in 3.5 wt% NaCl is studied by electrochemical impedance spectroscopy (EIS). A thick coating (∼1 mm) of 10, 15 and 20% PANi in marine grade PU, is cast over corrosion resistant aluminium alloy 2024 and its impedance characteristics are measured by EIS and compared with neat PU. On addition of 10% PANi, the impedance of the coating drastically comes down from 10⁹ to 10⁷ Ω. 20% is the maximum processable amount of PANi for the selected PU system. The coatings are exposed to 3.5 wt% NaCl and its impedance characteristics are monitored as a function of time. Changes in the impedance characteristics of the systems were found to occur as a function of the exposure time in all cases, though their evolution with time showed marked differences with PANi content. Water sorption and break down frequency are derived from the experimental results and analysed.     

黄杜中药漱口液对牙周病相关菌的影响及作用机理研究

探究了黄杜中药漱口液对牙周病相关菌活性的影响及作用机理。分别以牙周病相关致病菌牙龈卟啉单胞菌(Porphyromonas gingivalis,P. gingivalis)和益生菌食窦魏斯氏菌(Weissella cibaria,W. cibaria)为受试菌,采用微量肉汤稀释法考察黄杜中药漱口液对P. gingivalis、W. cibaria活性的影响,结果显示其对致病菌P. gingivalis具有显著的抑制作用(稳定期生长率<20%),对益生菌W. cibaria基本无抑制(稳定期生长率>80%)。通过考察细胞壁、细胞膜的完整性及能量代谢酶的活性进一步探究黄杜中药漱口液对受试菌的作用机理,结果显示,P. gingivalis胞外碱性磷酸酶(AKP)、K+、核酸、蛋白质含量显著升高(P<0.01),能量代谢酶琥珀酸脱氢酶(SDH)、苹果酸脱氢酶(MDH)活性显著下降(P<0.01),而对W. cibaria无显著影响(P>0.05)。推断出黄杜中药漱口液通过破坏致病菌P. gingivalis细胞膜、细胞壁完整性,扰乱能量代谢系统发挥抑菌作用,而对益...     

Analysis of electrochemical disintegration process of graphite matrix

The electrochemical method with ammonium nitrate as electrolyte was studied to disintegrate the graphite matrix from the simulative fuel elements for high temperature gas-cooled reactor. The influences of process parameters, including salt concentration, system temperature and current density, on the disintegration rate of graphite fragments were investigated in the present work. The experimental results showed that the disintegration rate depended slightly on the temperature and salt concentration. The current density strongly affected the disintegration rate of graphite fragments. Furthermore, the content of introduced oxygen in final graphite fragments was independent of the current density and the concentration of electrolyte. Moreover, the structural evolution of graphite was analyzed based on the microstructural parameters determined by X-ray diffraction profile fitting analysis using MAUD (material analysis using diffraction) before and after the disintegration process. It may safely be concluded that the graphite disintegration can be ascribed to the influences of the intercalation of foreign molecules in between crystal planes and the partial oxidation involved. The disintegration process was described deeply composed of intercalate part and further oxidation part of carbon which effected together to lead to the collapse of graphite crystals.     

The effect of electrolytic oxidation on the electrochemical properties of multi-walled carbon nanotubes

Multi-walled carbon nanotubes (MWNTs) were electrochemically oxidized by a constant-potential electrolysis method and then investigated in detail using scanning electron microscope, transmission electron microscope, FT-IR, electrical impedance spectroscopy, and cyclic voltammetry. The FT-IR spectra showed that the amount of hydroxyl generated on the surface of MWNTs increased with increasing the electrochemical oxidation time of MWNTs. The CV results, being conducted in nitrobenzene solution, showed that the nitrobenzene reduction current increased with the increase in oxidation time of the MWNTs within the first 60 min of electrolysis. An electrical equivalent circuit model for electrical impedance spectroscopy was further established to analyze the surface capacitance and resistance of the MWNTs, and the model results showed that the capacitance of the oxidized MWNTs increased greatly while the charge transfer resistance decreased, suggesting electrochemical oxidized MWNTs modified pyrolytic carbon electrode being an effective electrochemical sensor for nitrobenzene determination.