Immobilization and electrochemical behavior of gold nanoparticles modified leukemia K562 cells and application in drug sensitivity test

A new strategy for immobilization of tumor cells on electrode surface and accelerating electron transfer between electrode and the immobilized cells was proposed to study the electrochemical behavior of cells and the effect of antitumor drug on cell viability. The leukemia K562 cells immobilized in a microporous cellulose membrane were firstly modified with colloidal gold nanoparticles to retain efficiently the activity of immobilized living tumor cells and promote electron transfer between electroactive centers of the cells and the electrode, exhibiting a well-defined anodic peak of guanine at +0.830 V at 50 mV s⁻¹. The electrochemical response could be used to describe cell growth and evaluate the effectiveness of antitumor drug methotrexate on tumor cells. The proposed method offered potential advantages for drug sensitivity test with little usage of cells. It could be developed as a convenient means for the study of the tumor cells growth and the cytotoxicity of antitumor drugs.     

Characterization and preparation of core–shell type nanoparticle for encapsulation of anticancer drug

The aim of this study is to prepare delivery vehicles of paclitaxel using low molecular weight water-soluble chitosan (LMWSC) and evaluate them as an anticancer drug delivery system. LMWSC was modified with methoxy polyethylene glycol (LMWSC-MPEG, ChitoPEG), and then it was conjugated with cholesterol (LMWSC-MPEG-Chol). Core–shell type LMWSC-MPEG-Chol nanoparticles (LMWSC-NPs) were prepared by the dialysis method, and the core–shell structure was confirmed by ¹H NMR analysis. To this polymer, paclitaxel was encapsulated and core–shell type nanoparticles were prepared. The release tests indicated that release of paclitaxel from the core–shell type nanoparticles and its transport across the dialysis membrane was slower than dialysis of free paclitaxel. In a cytotoxicity study using CT26 cell, the paclitaxel-encapsulated core–shell type nanoparticles (LMWSC-NPs) showed a toxicity against tumor cells similar to paclitaxel itself. The results of a tumor inhibition test with CT26 implanted upon mouse tumor models in vivo indicated that the application of a dose of 10 mg/kg of LMWSC-NPT showed a superior survival rate, and a slower tumor growth than when paclitaxel alone was administered, although the tumor growth and survival rate were not significantly changed at a dose of 2 mg/kg. The LMWSC-NPT dose above 10 mg/kg showed a superior antitumor activity.     

Low-intensity red laser on the prevention and treatment of induced-oral mucositis in hamsters

ObjectiveThe purpose of this study was to investigate the effects of laser phototherapy as preventive and therapeutic regime on induced-oral mucositis in hamsters.DesignThe animals were divided into four groups: preventive cryotherapy, preventive laser, therapeutic laser and therapeutic control group. Mucositis was induced in hamsters by intraperitoneal injection of 5-fluorouracil (5-FU) and superficial scratching. All preventive treatment was performed on the right cheek pouch mucosa. The left pouch mucosa was used for a spontaneous development of mucositis and did not receive any preventive therapy. Laser parameters were: λ = 660 nm, P = 30 mW, D = 1.2 J/cm², Δt = 40 s, spot size 3 mm², I = 1 W/cm². Cryotherapy was done positioning ice packs in the hamster mucosa 5 min before 5-FU infusion and 10 min afterward. To study the healing of mucositis, the left pouch mucosa of each of the hamsters in the TLG received laser irradiation on the injured area. Irradiation parameters were kept the same as abovementioned. The control hamsters in the TCG did not receive any treatment. The mucositis degree and the animal’s body mass were evaluated. An assessment of blood vessels was made based on immunohistochemical staining.ResultsThe CG animals lost 15.16% of theirs initial body mass while the LG animals lost 8.97% during the first 5 days. The laser treated animals had a better clinical outcome with a faster healing, and more granulation tissue. The quantity of blood vessels at both LG and CG were higher than in healthy mucosa. Regarding the therapeutic analysis, the severity of the mucositis in the TLG was always lower than TCG. TLG presented higher organization of the granulation tissue, parallel collagen fibrils, and increased angiogenesis.ConclusionThe results suggest that laser phototherapy had a positive effect in reducing mucositis severity, and a more pronounced effect in treating established mucositis.     

Electrochemistry of the antibacterial and antifungal drug nitroxoline and its determination in bulk form, pharmaceutical formulation and human blood

Nitroxoline has been reduced at the mercury electrode in buffered solutions (pH 2?11) in two irreversible cathodic steps. The first step was attributed to reduction of –NO₂ group to the hydroxylamine stage and the second one to reduction-saturation of the C=N double bond. DC-polarographic and various adsorptive stripping voltammetric methods were developed for determination of nitroxoline in bulk form. Limits of quantitation of 1.02 × 10^?6, 3.05 × 10^?8, 9.01 × 10^?9, and 9.12 × 10^?10 M nitroxoline were achieved by means of the developed DC-polarography, differential-pulse-, linear-sweep-, and square-wave-adsorptive cathodic stripping voltammetric methods, respectively. All these electroanalytical methods were successfully applied for determination of nitroxoline in its Nibiol^® tablets. While only the developed adsorptive stripping voltammetry methods were successfully applied for determination of the drug in spiked human serum and for pharmacokinetic studies in real human plasma. The analysis was carried out without interference from common excipients and without the necessity for prior extraction or interaction with any reagent during the analysis.     

Electrokinetic pumping system based on nanochannel membrane for liquid delivery

Nonmechanical pumping of liquids is of key importance for applications from the biomedical microfluidic chip to drug delivery systems. In this paper, a new electrokinetic pump (EOP) system with polycarbonate nanochannel membrane sandwiched between two membrane holders was constructed. The pump was tested with water and phosphate buffer at 1-6 V applied voltage, the maximum pressure and flow rate are 0.32 MPa (3.2 atm) and 4.2 mL/min for phosphate buffer, respectively. This proof-of-concept pump shows its potential use for drugs or chemical agents delivery by the usage of different membrane materials.     

A novel method for Co(Ⅱ) and Cu(Ⅱ) analysis by capillary electrophoresis with chemiluminescence detection

Based on the fact that some metal ions can catalyze the chemiluminescence(CL)reaction of luminol with K_3Fe(CN)_6,a novel capillary electrophoresis CL method was developed for the determination of Co(Ⅱ)and Cu(Ⅱ).The separation was carried out with a 10 mmol/L sodium acetate solution containing 0.8 mmol/L luminol and 2.0 mmol/Lα-HIBA(adjusted to pH 4.8 by HAc solution).The post-capillary reagent was 2.0 mmol/L K_3Fe(CN)_6 which was adjusted to pH 13.0 by NaOH solution.Under the optimum conditions,the detection limits(S/N=3)for Co(Ⅱ)and Cu(Ⅱ)were 7.5×10~(-11)mol/L and 7.5×10~(-9)mol/L,with the linear range of 7.5×10~(-9)mol/L to 1.0×10~(-6)mol/L and 7.5×10~(-8)mol/L to 5.0×10~(-5)mol/L, respectively.     

Impedance spectroscopy and conductometric biosensing for probing catalase reaction with cyanide as ligand and inhibitor

In this work, a new biosensor was prepared through immobilization of bovine liver catalase in a photoreticulated poly (vinyl alcohol) membrane at the surface of a conductometric transducer. This biosensor was used to study the kinetics of catalase–H₂0₂ reaction and its inhibition by cyanide. Immobilized catalase exhibited a Michaelis–Menten behaviour at low H₂0₂ concentrations (< 100 mM) with apparent constant K_M^app = 84 ± 3 mM and maximal initial velocity V_M^app = 13.4 μS min^? 1. Inhibition by cyanide was found to be non-competitive and inhibition binding constant K_i was 13.9 ± 0.3 μM. The decrease of the biosensor response by increasing cyanide concentration was linear up to 50 μM, with a cyanide detection limit of 6 μM. In parallel, electrochemical characteristics of the catalase/PVA biomembrane and its interaction with cyanide were studied by cyclic voltammetry and impedance spectroscopy. Addition of the biomembrane onto the gold electrodes induced a significant increase of the interfacial polarization resistance R_P. On the contrary, cyanide binding resulted in a decrease of Rp proportional to KCN concentration in the 4 to 50 μM range. Inhibition coefficient I₅₀ calculated by this powerful label-free and substrate-free technique (24.3 μM) was in good agreement with that determined from the substrate-dependent conductometric biosensor (24.9 μM).     

Amperometric glucose sensor based on glucose oxidase immobilized on gelatin-multiwalled carbon nanotube modified glassy carbon electrode

We investigated the direct electrochemistry of glucose oxidase (GOx) at gelatin-multiwalled carbon nanotube (GCNT) modified glassy carbon electrode (GCE). GOx was covalently immobilized onto GCNT modified GCE through the well known glutaraldehyde (GAD) chemistry. The immobilized GOx showed a pair of well-defined reversible redox peaks with a formal potential (E⁰′) of ? 0.40 V and a peak to peak separation (ΔE_p) of 47 mV. The surface coverage concentration (Г) of GOx in GCNT/GOx/GAD composite film modified GCE was 3.88 × 10^? 9 mol cm^? 2 which indicates the high enzyme loading. The electron transfer rate constant (k_s) of GOx immobilized onto GCNT was 1.08 s^? 1 which validates a rapid electron transfer processes. The composite film shows linear response towards 6.30 to 20.09 mM glucose. We observed a good sensitivity of 2.47 μA mM^?1 cm^? 2 for glucose at the composite film. The fabricated biosensor displayed two weeks stability. Moreover, it shows no response to 0.5 mM of ascorbic acid (AA), uric acid (UA), acetaminophen (AP), pyruvate (PA) and lactate (LA) which shows its potential application in the determination of glucose from human serum samples. The composite film exhibits excellent recovery for glucose in human serum at physiological pH with good practical applicability.     

Selective binding of bile salts by β-cyclodextrin derivatives with appended quinolyl arms

Two β-cyclodextrin derivatives bearing appended quinolyl and isoquinolyl arms,i.e.mono-(6-quinolyl- 6-deoxy)-β-cyclodextrin(1) and mono-(6-isoquinolyl-6-deoxy)-β-cyclodextrin(2) were synthesized in satisfactory yields and fully characterized.Their original conformations and binding behaviors toward four bile salt guests,that is,sodium cholate(CA),sodium deoxycholate(DCA),sodium glycocholate (GCA),and sodium taurocholate(TCA),were investigated by means of fluorescence,circular dichroism and 2D NMR spectroscopy.The study of solution structures revealed that both quinolyl and isoquinolyl arms were located outside the cyclodextrin cavity.The results obtained from the fluorescence titrations showed that the binding abilities of hosts 1 and 2 with selected bile salts varied in an order of DCA > CA > GCA.The selective binding of hosts toward bile salt guests was discussed from the viewpoints of induced-fit and multiple binding.     

Determination of resveratrol in red wine by solid phase extraction-flow injection chemiluminescence method

A sensitive flow injection chemiluminescence method has been developed for the detection of resveratrol in red wine based on the fact that resveratrol can greatly enhance chemiluminescence reaction between KMnO_4 and HCHO in sulfuric acid medium. Analytes were pre-concentrated on solid sorbents (C_(18) solid-phase extraction cartridges).Under the optimum conditions,the proposed method allows the measurement of resveratrol over the range of 1.32×10~(-8) to 1.32×10~(-5) mol/L with a detection limit of 3.30×10~(-9) mol/L,and the relative standard deviation for 1.32×10~(-5) mol/L resveratrol (n=11) is 3.8%.This method has been successfully applied for the determination of the resveratrol in red wine.Furthermore,the possible reaction mechanism was also discussed.     

Design and synthesis of novel water-soluble amino acid derivatives of chlorin p6 ethers as photosensitizer

Eight new water-soluble amino acid derivatives of chlorin p₆ ethers 6a-h were designed and synthesized using purpurin-18 (2) as key intermediate. All target compounds exhibited better phototoxicity than talaporfin and the most phototoxic compound 6d showed IC₅₀ values of 0.20 μmol/L against A549 cell and 0.41 μmol/L against B16-F10 cell, which represented 31- and 24-fold increase of PDT antitumor efficacy compared to talaporfin.     

Conformational and stereoelectronic investigation of chloromethyl methyl sulfide and its sulfinyl and sulfonyl analogs

Three compounds based on polyoxometalate building blocks, [Cu(en)₂]{[Cu(en)₂]₂[Mo^VI₅Mo^V₃V^IV₈O₄₀(PO₄)]} · 4H₂O (1), [Co(en)₂]{[Co(en)₂]₂[HMo^VI₄Mo^V₄V^IV₈O₄₀(PO₄)]} · 5H₂O (2) and [Ni(en)₂]{[Ni(en)₂]₂[Mo^VI₅Mo^V₃V^IV₈O₄₀(VO₄)]} · 2H₂O (3) (en = ethylenediamine), have been synthesized and characterized by elemental analysis, IR, XPS, XRD, TGA and single-crystal X-ray diffraction analysis. The result of structure determination shows that isomorphic compounds 1, 2 and 3 feature a one-dimensional chain built from the reduced tetra-capped pseudo-Keggin polyoxoanion, which is further interconnected by [M(en)₂]²⁺ (M = Cu, Co and Ni) groups via the terminal oxygen atoms of polyoxoanions. The crystal data for these compounds are the following: 1, monoclinic, space group C2/c, a = 26.702(3) Å, b = 13.4539(14) Å, c = 19.5987(19) Å, β = 108.650(2)°, V = 6671.0(12) Å³, Z = 4; 2, monoclinic, space group C2/c, a = 26.244(3) Å, b = 13.5070(17) Å, c = 19.581(3) Å, β = 106.881(2)°, V = 6641.8(15) Å³, Z = 4; 3, monoclinic, space group C2/c, a = 26.2789(15) Å, b = 13.5408(6) Å, c = 19.6312(9) Å, β = 106.2590(10)°, V = 6706.1(6) Å³, Z = 4. Variable-temperature magnetic susceptibility measurements of compounds 1 and 3 reveal the feature of antiferromagnetic exchange in these compounds.     

Synthesis of an antimetastatic tetrasaccharide β-D-Gal-(1→4)-β-d-GlcpNAc-(1→6)-α-D-Manp-(1→6)-β-D-Manp-OMe

An antimetastatic tetrasaccharide T₁,β-D-Gal-（1→4）-β-D-GlcpNAc-（1→6）-α-D-Manp-（1→6）-β-D-Manp-OMe,was synthesized with two approaches.The first approach was a conventional method employing thioglycoside and Koenigs-Knorr glycosylation reaction in 24%overall yield.The second one was a novel route through the azidoiodo-glycosylation strategy by using 2-iodo-2-deoxylactosyl azide as the donor in 36%overall yield.     

Hydrothermal conversion of lignocellulosic biomass into high-value energy storage materials

Preparation of hierarchically porous, heteroatom-rich nanostructured carbons through green and scalable routes plays a key role for practical energy storage applications. In this work, naturally abundant lignocellulosic agricultural waste with high initial oxygen content, hazelnut shells, were hydrothermally carbonized and converted into nanostructured ‘hydrochar'. Environmentally benign ceramic/magnesium oxide(Mg O) templating was used to introduce porosity into the hydrochar. Electrochemical performance of the resulting material(HM700) was investigated in aqueous solutions of 1 M H_2SO_4, 6 M KOH and1 M Na_2SO_4, using a three-electrode cell. HM700 achieved a high specific capacitance of 323.2 F/g in 1 M H_2SO_4(at 1 A/g,-0.3 to 0.9 V vs. Ag/Ag Cl) due to the contributions of oxygen heteroatoms(13.5 wt%)to the total capacitance by pseudo-capacitive effect. Moreover, a maximum energy density of 11.1 Wh/kg and a maximum power density of 3686.2 W/kg were attained for the symmetric supercapacitor employing HM700 as electrode material(1 M Na_2SO_4, E = 2 V), making the device promising for green supercapacitor applications.     

Potentiometric determination of diclofenac in pharmaceutical formulation by membrane electrode based on ion associate with base dye

The characteristics,performance and application of membrane electrode based on ion associate of diclofenac with base dye Safranine T are described.The electrode response to diclofenac has the sensitivity of 47±1.0 mV decade~(-1)over the range of 5×10~(-5)to 5×10~(-2)mol/L at pH 6-12,and the detection limit of 3.2×10~(-5)mol/L.The electrode is easy assembled at a relatively low cost has fast response time(2-4 s)and can be used for a period up to 3.5 months without any considerable divergence in potential.The proposed sensor displayed good selectivity for diclofenac in the presence of different substances.It was used to determine diclofenac in pharmaceuticals by means of the standard addition method.     

Photodynamic therapy induces selective extravasation of macromolecules: Insights using intravital microscopy

Photodynamic therapy (PDT) with Visudyne^® acts by direct cellular phototoxicity and/or by an indirect vascular-mediated effect. Here, we demonstrate that the vessel integrity interruption by PDT can promote the extravasation of a macromolecular agent in normal tissue. To obtain extravasation in normal tissue PDT conditions were one order of magnitude more intensive than the ones in tissue containing neovessels reported in the literature.Fluorescein isothiocyanate dextran (FITC-D, 2000 kDa), a macromolecular agent, was intravenously injected 10 min before (LK0 group, n = 14) or 2 h (LK2 group, n = 16) after Visudyne^®-mediated PDT in nude mice bearing a dorsal skin fold chamber. Control animals had no PDT (CTRL group, n = 8). The extravasation of FITC-D from blood vessels in striated muscle tissue was observed in both groups in real-time for up to 2500 s after injection. We also monitored PDT-induced leukocyte rolling in vivo and assessed, by histology, the corresponding inflammatory reaction score in the dorsal skin fold chambers.In all animals, at the applied PDT conditions, FITC-D extravasation was significantly enhanced in the PDT-treated areas as compared to the surrounding non-treated areas (p < 0.0001). There was no FITC-D leakage in the control animals. Animals from the LK0 group had significantly less FITC-D extravasation than those from the LK2 group (p = 0.0002). In the LK0 group FITC-D leakage correlated significantly with the inflammation (p < 0.001).At the selected conditions, Visudyne^®-mediated PDT promotes vascular leakage and FITC-D extravasation into the interstitial space of normal tissue. The intensity of vascular leakage depends on the time interval between PDT and FITC-D injection. This concept could be used to locally modulate the delivery of macromolecules in vivo.     

Sensitive lactate determination based on acclimated mixed bacteria and palygorskite co-modified oxygen electrode

A sensitive bacteria biosensor was prepared for the detection of trace lactate. The sensitive bioelement, Lactobacillus bulgaricus and Streptococcus thermophilus mixed cultrue, and palygorskite, a perfect matrix for bacteria, was co-immobilized on the surface of oxygen electrode. The biosensor possesses fine selective specificity, good sensitivity and longer operational life time, which were due to the mutual help relationship of symbiotic bacteria and 240 days acclimation with lactate as the carbon source. Hydrodynamic amperometry, an advanced electrochemical method, is suitable for on-line monitoring the concentration change of dissolved oxygen that is closely accompanied with the metabolism of lactate. Electrochemical data show that the current is very sensitive to the changes of the concentration of lactate. The response current was linear with lactic acid concentration in the range from 0 to 300 μmol L^? 1, where the response time is no more than 240 s (R = 0.9952), and the sensitivity was 1.87 mA mol^? 1 L. Experiments show the biosensor is also very useful for long time on-line monitoring of lactate, such as fermentation progress.     

Synthesis and characterization of a tetranuclear copper(Ⅱ) complex with a chiral Schiff base ligand

The title complex l-[Cu^Ⅱ₄（Hvap）₂（vap）₂（MeOH）₂]（CIO₄）₂ 1 has been synthesized and characterized by EA. IR,TGA,solid-state CD spectra and X-ray single-crystal analyses（l-H₂vap’.a Schiff base ligand derived from the condensation of o-vanillin and l-2-amino-3-phenyl-l-propanol）.Complex 1 crystallizes in monoclinic system,chiral space group P2₁ with a =10.4257（18）.b = 21.695（4）,c = 15.721（3）A,β= 94.443（3）.V= 3545.1（11） ³,Z=2,Cu₄C₇₀H₇₈N₄O₂₂Cl₂.Mr= 1652.42,D_c= 1.548 g/cm³, F（000）= 1704 andμ（MoKα） = 1.338 mm^-1.The final R = 0.0682 and wR = 0.1420 for 6170 observed reflections with I > 2σ（I） and R = 0.1775 and wR = 0.1830 for all data.The structure of complex 1 contains a boat-shaped(Cu₄O₄} motif.The solid-state CD spectra confirm the chiral nature of complex 1.     

Fabrication of a nano-sized ZSM-5 zeolite with intercrystalline mesopores for conversion of methanol to gasoline

Carbon deposition during methanol to hydrocarbons leads to the quick deactivation of ZSM-5 catalyst and it is one of the major problems for this technology. Decreasing the crystal size or introducing mesopores into ZSM-5 zeolites can improve its diffusion property and decrease the coke formation. In this paper, nano-sized ZSM-5 zeolite with intercrystalline mesopores combining the mesoporous and nanosized structure was fabricated. For comparison, the mesoporous ZSM-5 and nano-sized ZSM-5 were also prepared. These catalyst samples were characterized by XRD, BET, NH3-TPD, TEM, Py-IR and TG techniques and used on the conversion of methanol to gasoline in a fixed-bed reactor at T = 405 °C, WHSV = 4.74 h-1and P = 1.0 MPa. It was found that the external surface area of the nano-sized ZSM-5 zeolite with intercrystalline mesopores reached 104 m2/g, larger than that of mesoporous ZSM-5(66 m2/g) and nanosized ZSM-5(76 m2/g). Catalytic lifetime of the nano-sized ZSM-5 zeolite with intercrystalline mesopores was 93 h, which was only longer than that of mesoporous ZSM-5(86 h), but shorter than that of nanosized ZSM-5(104 h). Strong acidity promoted the coke formation and thus decreased the catalytic lifetime of the nano-sized ZSM-5 zeolite with intercrystalline mesopores though it presented large external surface that could improve the diffusion property. The special zeolite catalyst was further dealuminated to decrease the strong acidity. After this, its coke formation rate was slowed and catalytic lifetime was prolonged to 106 h because of the large external surface area and decreased weak acidity. This special structural zeolite is a potential catalyst for methanol to gasoline reaction.