Electrocatalytic Determination of Ascorbic Acid Using a Palladium Coated Nanoporous Gold Film Electrode

Cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behavior of ascorbic acid (AA) on palladium coated nanoporous gold film (PdNPGF) electrode. The deposition of palladium was done through oxidation of copper UPD layer by palladium ions. This low Pd‐loading electrode behaved as the nanostructured Pd for electrocatalytic reaction. The PdNPGF electrode exhibits excellent electrocatalytic behavior by enhancing the AA oxidation peak current due to synergistic influence of the Pd film and NPGF. The kinetic parameters such as electron transfer coefficient, α, was 0.47 and the voltammetric responses of the PdNPGF electrode were linear against concentration of AA in the ranges of 2.50–33.75 mM and 0.10–0.50 mM with CV and DPV respectively.     

A Structural and Calorimetric Study on the Interaction Between Jack Bean Urease and Cyanide Ion

The cyanide ion was studied as an effecter of Jack bean urease at 300 K in 30 mmol⋅L⁻¹ Tris buffer, pH=7. The inhibition was investigated by isothermal titration calorimetry (ITC). The extended solvation model was used for CN⁻+JBU interaction over the whole range of CN⁻ concentrations. The binding parameters recovered from the solvation model were attributed to the interaction with cyanide ion. It was found that cyanide ion acted as a noncooperative inhibitor of urease, and there is a set of 12 identical and independent binding sites for CN⁻ ions. The dissociation equilibrium constant is 749.99 μmol⋅L⁻¹. The molar enthalpy of binding is ΔH=−13.60 kJ⋅mol⁻¹.     

On the prediction of equilibrium phase behavior of amino acids in aqueous and aqueous-electrolyte solutions using SAFT equation of state

We present an approach based on the statistical associating fluids theory (SAFT) to predict the solubility of amino acids in aqueous and aqueous-electrolyte solutions. This approach can describe the association interactions and their effects on the solubility of amino acids. Using the experimental data of activity coefficients of amino acids in water, the parameters of SAFT model for amino acids are obtained. The solubility of several amino acids in the temperature range of 273.15–373.15 K is predicted. Results obtained from the model are in a good accordance with the experimental data. Also, we examine the effect of pH on the solubility of dl-methionine. Addition of an extra amino acid to the binary solution of amino acid + water makes the system more complex. To check the accuracy of model, we study the ternary solution of dl-serine + dl-alanine + water and dl-valine + dl-alanine + water. Predicted results depict that the proposed model has the ability to describe the ternary solution of amino acids, accurately. Finally, the solubility of amino acids in aqueous-electrolyte solutions is investigated. The long-range interactions caused by the presence of ions affects the solubility of amino acids, leading them to be salted in or out. To treat this kind of interaction, the restrictive primitive mean spherical approximation (RP-MSA) is coupled with the SAFT equation of state. The proposed model can accurately predict the solubility of amino acids in aqueous-electrolyte solutions.     

Corrosion Inhibition of Mild Steel by Safflower (Carthamus tinctorius) Extract: Polarization,EIS, AFM,SEM, EDS,and Artificial Neural Network Modeling

Inhibitory action of safflower (Carthamus tinctorius) extract (SE) was investigated in hydrochloric acid solution through electrochemical (polarization, EIS), and surface analysis (optical microscopy/atomic force microscopy (AFM)/scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS)) techniques. In addition, Inhibition efficiency was predicted by neural network (NN) modeling in elevated temperatures and different acid concentrations. The thermodynamic adsorption parameters propose that this inhibitor retard both cathodic and anodic processes through physical adsorption and blocking the active corrosion sites. Surface analysis techniques confirm the inhibitor adsorption on the metal surface, which is in accordance with the variation of apparent activation energy of corrosion. Finally, inhibition efficiency is discussed in terms of protective film formation.     

Optimized preparation and preliminary evaluation of [64Cu]–DOTA–trastuzumab for targeting ErbB2/Neu expression

Breast cancer radioimmunoscintigraphy targeting HER2/neu expression is a growing field of work in nuclear medicine research. Trastuzumab is a monoclonal antibody that binds with high affinity to HER2/neu, which is over expressed on breast and other tumors. Developing new tracers for the detection of this cancer is of great interest. In this study, trastuzumab was successively labeled with [⁶⁴Cu]CuCl₂ after conjugation with DOTA-NHS-ester. The conjugate was purified by molecular filtration, the average number of DOTA conjugated per mAb was calculated and total concentration was determined by spectrophotometric method. DOTA–trastuzumab was labeled with ⁶⁴Cu produced by ⁶⁸Zn(p,αn)⁶⁴Cu nuclear reaction (30 MeV protons at 180 μA). Radiochemical purity, integrity of protein after radiolabeling and immunoreactivity of radiolabeled mAb trastuzumab with HER2/neu antigen and SkBr3 cell line were performed by RIA. In vitro stability of radiolabeled mAb in human serum was determined by thin layer chromatography. In vitro internalization studies were performed with the SkBr3 cell line and the tissue biodistribution of the ⁶⁴Cu–DOTA–trastuzumab was evaluated in wild-type rat (90 ± 5.5 μCi, 2, 6, 12, 24 h p.i.). The radioimmunoconjugate was prepared with a radiochemical purity of higher than 96 ± 0.5 % (ITLC) and specific activity as high as 5.3 μCi/μg. The average number of chelators per antibody for the conjugate used in this study was 5.8/1. The sample was showed to have similar patterns of migration in the gel electrophoresis. The ⁶⁴Cu–DOTA–trastuzumab showed high immunoreactivity towards HER2/neu antigen and SkBr3 cell line. In vitro stability of the labeled product was found to be more than 94 % in PBS and 82 ± 0.5 % in human serum over 48 h. In vitro internalization studies of the ⁶⁴Cu–DOTA–trastuzumab showed that up to 11.5 % of the radioimmunoconjugate internalized after 10 h. The accumulation of the radiolabeled mAb in liver, skin, intestine, lung, spleen, kidney and other tissues demonstrates a similar pattern to the other radiolabeled anti-HER2 immunoconjugates. ⁶⁴Cu–DOTA–trastuzumab is a potential compound for molecular imaging of PET for diagnosis and treatment studies and follow-up of HER2 expression in oncology.     

Sensitive determination of methadone in human serum and urine by dispersive liquid–liquid microextraction based on the solidification of a floating organic droplet followed by HPLC–UV

Dispersive liquid–liquid microextraction based on solidification of floating organic droplet was developed for the extraction of methadone and determination by high‐performance liquid chromatography with UV detection. In this method, no microsyringe or fiber is required to support the organic microdrop due to the usage of an organic solvent with a low density and appropriate melting point. Furthermore, the extractant droplet can be collected easily by solidifying it at low temperature. 1‐Undecanol and methanol were chosen as extraction and disperser solvents, respectively. Parameters that influence extraction efficiency, i.e. volumes of extracting and dispersing solvents, pH, and salt effect, were optimized by using response surface methodology. Under optimal conditions, enrichment factor for methadone was 134 and 160 in serum and urine samples, respectively. The limit of detection was 3.34 ng/mmL in serum and 1.67 ng/mL in urine samples. Compared with the traditional dispersive liquid–liquid microextraction, the proposed method obtained lower limit of detection. Moreover, the solidification of floating organic solvent facilitated the phase transfer. And most importantly, it avoided using high‐density and toxic solvents of traditional dispersive liquid–liquid microextraction method. The proposed method was successfully applied to the determination of methadone in serum and urine samples of an addicted individual under methadone therapy.     

Biocompatible APTES–PEG Modified Magnetite Nanoparticles: Effective Carriers of Antineoplastic Agents to Ovarian Cancer

Magnetite nanoparticles are particularly attractive for drug delivery applications because of their size-dependent superparamagnetism, low toxicity, and biocompatibility with cells and tissues. Surface modification of iron oxide nanoparticles with biocompatible polymers is potentially beneficial to prepare biodegradable nanocomposite-based drug delivery agents for in vivo and in vitro applications. In the present study, the bare (10 nm) and polyethylene glycol (PEG)–(3-aminopropyl)triethoxysilane (APTES) (PA) modified (17 nm) superparamagnetic iron oxide nanoparticles (SPIO NPs) were synthesized by coprecipitation method. The anticancer drugs, doxorubicin (DOX) and paclitaxel (PTX), were separately encapsulated into the synthesized polymeric nanocomposites for localized targeting of human ovarian cancer in vitro. Surface morphology analysis by scanning electron microscopy showed a slight increase in particle size (27?±?0.7 and 30?±?0.45 nm) with drug loading capacities of 70 and 61.5 % and release capabilities of 90 and 93 % for the DOX- and PTX-AP-SPIO NPs, respectively (p?<?0.001). Ten milligrams/milliliter DOX- and PTX-loaded AP-SPIO NPs caused a significant amount of cytotoxicity and downregulation of antiapoptotic proteins, as compared with same amounts of free drugs (p?<?0.001). In vivo antiproliferative effect of present formulation on immunodeficient female Balb/c mice showed ovarian tumor shrinkage from 2,920 to 143 mm³ after 40 days. The present formulation of APTES–PEG-SPIO-based nanocomposite system of targeted drug delivery proved to be effective enough in order to treat deadly solid tumor of ovarian cancer in vitro and in vivo.     

Removal of Oil Spills from Salty Waters by Commercial Organoclays

In this study two commercial organoclays, Cloisite 15A and Cloisite 30B, were used to investigate their potential for removing of light and heavy crude oils from salty waters. The results of batch kinetic studies indicated that the equilibrium time can be reached within 25–30 minutes of contact time. In addition experiments were performed to determine the effect of salinity, temperature, pH and mixing time on the adsorption process. The adsorption isotherms were obtained for the crude oils at equilibrium, at an optimum pH value of 11.73 and temperature of 19°C for which the initial oil contents varied in the range of 100 to 2000 ppm. Experimental results showed that oil sorption onto these organoclays can be described by Freundlich isotherm. Further, it was found that the oil removal efficiency for Cloisite 30B is higher than that of Cloisite 15A and the greater sorption was observed for Gachsaran crude oil onto the organoclays over Soroosh crude oil.     

Comparison Between Long- and Short-Chain Organoclays for Oil Removal from Salty Waters

Two commercial powdered organoclays, Cloisite 15A and Cloisite 30B, as long-chain organoclays, and two organically modified clays with tetramethylammonium chloride (TMA-clay), as short-chain organoclays were used in this study to investigate their potentials for crude oil removal from salty waters. Batch experiments were performed to examine the effect of contact time and pH on the adsorption process. The results showed that the equilibrium time was reached within 25–30 and 50–55 minutes of contact time for long and short-chain organoclays, respectively. In addition, adsorption isotherms were obtained at an optimum pH value of 11.73 and temperature of 19°C for which initial oil contents varied in the range of 100 to 2000 ppm. Experimental results indicated that the sorption of oil onto Cloisite 15A, Cloisite 30B and the organically modified clays can be described by Freundlich isotherm and oil sorption followed the order of modified Cloisite Na > Cloisite 30B > Cloisite 15A > a modified local clay.      

Poly(lactic acid)/coplasticized thermoplastic starch blend: Effect of plasticizer migration on rheological and mechanical properties

Polylactic acid (PLA) and thermoplastic starch (TPS) are known as bio‐based and biodegradable thermoplastic polymers that can be used in different applications owing to their inherent physical and mechanical properties. In order to reduce the higher costs of PLA and tuning its physical and mechanical properties suitable for short life packaging applications, blending of PLA with the TPS, more economical biodegradable polymer, has been considered in academic and industrial researches. However, melt blending of PLA with TPS without compatibilization process caused some drawbacks such as coarsening morphology and declining mechanical properties and ductility because of thermodynamic immiscibility, which may restrict its usage in packaging applications. Subsequently, our approach in this research is compatibilization of PLA/TPS blends by utilization of primary well tuning of TPS formulation with a combination of sorbitol and glycerol plasticizers. In this work, the wide composition range of melt mixed PLA/TPS blends was prepared using a laboratory twin screw extruder. The effects of microstructure on the rheological and mechanical properties of PLA/TPS blends were studied using different methods such as scanning electron microscopy (SEM) images, contact angle, oscillatory shear rheological measurements, and tensile and impact strength mechanical tests. The rheological and mechanical properties were interpreted according to the morphological features and considering the possibility of plasticizer migration from TPS to PLA phase during melt blending. Reduction in complex viscosity and storage modulus of PLA matrix samples indicates the improved melt processability of blends. Finally, in comparison with mechanical results reported in literature, our simple approach yielded the blends with elastic modulus and ductility comparable with those of chemically compatibilized PLA/TPS blends.