Ede Bodoki

Simultaneous Enantiospecific Recognition of Several β-Blocker Enantiomers Using Molecularly Imprinted Polymer-Based Electrochemical Sensor

The development of a chiral electrochemical sensor using an electrogenerated molecularly imprinted polymer (MIP)-based ultrathin film using R(+)-atenolol (ATNL) as a template was reported. The proposed sensor exhibited distinctive enantiospecific oxidation peaks toward the R-antipodes of four β-blocker representatives and additional oxidation peaks common to both enantiomers of each studied β-blocker, allowing thus the simultaneous analysis of all of their enantiomers in a single analysis. The specific preconditioning of the polymer by alternative exposure to aqueous and nonaqueous medium was proven to be essential for the chiral recognition ability of the obtained sensor. The rebinding property of the MIP film was studied by using a well-known redox probe, a change in the morphology and diffusive permeability of the thin polymeric layer in the presence of its template being observed. The applicability of the optimized analytical procedure was demonstrated by the analysis of ATNLs enantiomers in the range of 1.88 × 10(-7)-1.88 × 10(-5) mol/L. The developed polymeric interface is the first reported transductor of a chiral electrochemical sensor able to exhibit simultaneous enantiospecificity toward several β-blocker representatives extensively used in the pharmaceutical and biomedical fields, offering good prospects in the simple, cost-effective, and fast assessment of their enantiomeric ratio and total concentration.

Recent advances in capillary electrochromatography using molecularly imprinted polymers.

There is an increased and continuous need for developing new methods for the separation and quantification of an increasing number of analytes in the environmental, pharmaceutical, pharmacological, and toxicological sciences. CEC is still withholding its popularity, representing a viable alternative to the more conventional techniques (HPLC, GC) due to the numerous advantages, such as, low sample/reagent volumes, high separation efficiencies, hybrid separation principle, etc. One particular promising direction in CEC is the use of molecularly imprinted polymers (MIPs) as stationary phases. They are usually immobilized in the capillary column as a continuous polymeric monolith or as a thin polymer coating attached to the capillarys inner wall. Another emerging trend is the use of MIPs in the form of nanoparticles as a pseudostationary phase. This review discusses the recent developments (2011–2013) in finding the optimal polymerization mixture and the suitable MIP format that should be employed in CEC separations. The most important applications of MIPs in CEC technique are also highlighted.

Chiral recognition and quantification of propranolol enantiomers by surface enhanced Raman scattering through supramolecular interaction with β-cyclodextrin

A simple, fast and accurate method of chiral recognition and quantification of propranolol enantiomers by surface enhanced Raman scattering (SERS) and multivariate regression analysis through supramolecular interaction with β-cyclodextrin is reported. Computational chemistry served as a tool of elucidating the underlying mechanism of molecular interactions responsible for chiral discrimination. The influence of several factors (nature and concentration of chiral auxiliary, selector-selectand ratio, pH, interaction time, etc.) over the obtained SERS spectra was assessed, followed by the construction of the chemometric model with the optimized operational conditions. The performance of the obtained semi-empirical model was established using a validation set of pure enantiomers and its intended use was demonstrated by the assessment of the enantiomeric excess of propranolol in pharmaceutical formulations (tablets) without the need of tedious and expensive chiral separation. The obtained results were also confirmed by chiral high-performance liquid chromatography.

Generic systems for the enantioseparation of basic drugs in NACE using single-isomer anionic CDs

The enantioseparation of 10 basic drugs was evaluated in NACE systems using heptakis(2-O-methyl-3-O-acetyl-6-O-sulfo)-β-CD (HMAS-β-CD). For this purpose, a D-optimal design with 21 experimental points was applied. Four antifungal agents (econazole, isoconazole, miconazole, sulconazole), three local anesthetics (bupivacaine, mepivacaine and prilocaine), two sympathomimetics (salbutamol and terbutaline) and one β-blocker (carvedilol) were selected as basic model analytes. The influence on the enantiomeric resolution of anionic CD and BGE anion concentrations as well as the BGE anion nature was investigated. For all studied analytes, the enantiomeric resolution was shown to be significantly influenced by the CD concentration. Based on the observed results, a generic NACE system was recommended, namely 20mM HMAS-β-CD and 10mM ammonium camphor SO(3)(-) in methanol acidified with 0.75 M formic acid. Moreover, this NACE system was compared to previous conditions with heptakis(2,3-di-O-methyl-6-O-sulfo)-β-CD (HDMS-β-CD) or heptakis(2,3-di-O-acetyl-6-O-sulfo)-β-CD (HDAS-β-CD). Finally, two generic systems using either HDAS-β-CD or HMAS-β-CD were proposed and evaluated for the enantioseparation of ketamine and norketamine after incubation of ketamine in phenobarbital-induced male rat liver microsomes systems.

THE ANALYSIS OF SMALL IONS WITH PHYSIOLOGICAL IMPLICATIONS USING CAPILLARY ELECTROPHORESIS WITH CONTACTLESS CONDUCTIVITY DETECTION

Simultaneous electrophoretic separation of inorganic anions and cations from ground waters by dual opposite end injection and their capacitively coupled contactless conductometric detection is described. The chemometry assisted method development revealed that using this type of detection, apart from many advantages, implies a careful fine tuning of experimental variables. Proper choice of buffer components is the most critical aspect of the recorded signals quality and the obtained resolution, where minor changes could lead to major changes in the recorded electropherograms. From a big variety of acidic and basic electrolytes, a pyromellitic acid/citric acid based buffer (pH = 3.70) was chosen for the baseline separation of 11 cations and anions in a single, less than 3 min run, using a PVA coated fused silica capillary. The estimated limits of detection (0.07–2 ppm) and defined limits of quantification (0.3–7 ppm) were comparable or better than those described for indirect UV detection, allowing much broader linear ranges (up to 120 ppm) for most of the studied ions. Following method validation the method was successfully applied for the assessment of inorganic ion content of 51 geotagged drinking water (domestic well) samples collected from the rural area of Cluj County, Romania, and correlations between sample composition and their geographical origin were identified by multivariate data analysis.

Study of nucleic acid-ligand interactions by capillary electrophoretic techniques: A review.

The understanding of nucleic acids-ligand (proteins, nucleic acids or various xenobiotics) interactions is of fundamental value, representing the basis of complex mechanisms that govern life. The development of improved therapeutic strategies, as well as the much expected breakthroughs in case of currently untreatable diseases often relies on the elucidation of such biomolecular interactions. Capillary electrophoresis (CE) is becoming an indispensable analytical tool in this field of study due to its high versatility, ease of method development, high separation efficiency, but most importantly due to its low sample and buffer volume requirements. Most often the availability of the compounds of interest is severely limited either by the complexity of the purification procedures or by the cost of their synthesis. Several reviews covering the investigation of protein-protein and protein-xenobiotics interactions by CE have been published in the recent literature; however none of them promotes the use of these techniques in the study of nucleic acid interactions. Therefore, various CE techniques applicable for such interaction studies are discussed in detail in the present review. The paper points out the particular features of these techniques with respect the estimation of the binding parameters, in analytical signal acquisition and data processing, as well as their current shortcomings and limitations.

A micellar electrokinetic chromatography–mass spectrometry approach using in-capillary diastereomeric derivatization for fully automatized chiral analysis of amino acids

In the context of bioanalytical method development, process automatization is nowadays a necessity in order to save time, improve method reliability and reduce costs. For the first time, a fully automatized micellar electrokinetic chromatography-mass spectrometry (MEKC-MS) method with in-capillary derivatization was developed for the chiral analysis of d- and l-amino acids using (-)-1-(9-fluorenyl) ethyl chloroformate (FLEC) as labeling reagent. The derivatization procedure was optimized using an experimental design approach leading to the following conditions: sample and FLEC plugs in a 2:1 ratio (15s, 30mbar: 7.5s, 30mbar) followed by 15min of mixing using a voltage of 0.1kV. The formed diastereomers were then separated using a background electrolyte (BGE) consisting of 150mM ammonium perfluorooctanoate (APFO) (pH=9.5) and detected by mass spectrometry (MS). Complete chiral resolution was obtained for 8 amino acids, while partial separation was achieved for 6 other amino acid pairs. The method showed good reproducibility and linearity in the low micromolar concentration range. The applicability of the method to biological samples was tested by analyzing artificial cerebrospinal fluid (aCSF) samples.

Application of capacitively coupled contactless conductivity as an external detector for zone electrophoresis in poly(dimethylsiloxane) chips

In this work, lab‐made PDMS microfluidic chips were matched to a capacitively coupled contactless conductivity detector (C4D) having external in‐plane electrodes (eDAQ, Australia). The advantages of this type of C4D are the choice to reversibly place or remove the microchip onto/from the detector and to freely variate the position of the detection (separation length) on the microchip. The thickness of the bottom layer of the PDMS chip was optimized to achieve sensitive detection during the electrophoretic separation. PDMS chips with 100 μm bottom layer used with the C4D platform were tested by CZE of a mixture of seven anions and different types of real samples. Using split‐flow pressure sample injection and effective length of 6.5 cm, the numbers of theoretical plates were in the range of 4000–6000 (63 000–93 000/m) and the LODs amounted to 3.66–14.7 μmol/L (0.13–2.26 μg/mL) for the studied anions.

Zein Nanoparticles Uptake and Translocation in Hydroponically Grown Sugar Cane Plants

The main objective of this study was to investigate the uptake and translocation of positively charged zein nanoparticles (ZNPs) in hydroponically grown sugar cane plants. Fluorescent ZNPs (spherical and measuring an average diameter 135 ± 3 nm) were synthesized by emulsion-diffusion method from FITC-tagged zein. Fluorescent measurement following digestion of plant tissue indicated that sugar cane roots had a significant adhesion of ZNPs, 342.5 ± 24.2 μg NPs/mg of dry matter, while sugar cane leaves contained a very limited amount, 12.9 ± 1.2 μg NPs/mg dry matter for high dose(1.75 mg/ml) after 12 h. Confocal microscopy studies confirmed presence of fluorescent ZNPs in the epidermis and endodermis of the root system. Given their ability to adhere to roots for extended periods of time, ZNPs are proposed as effective delivery systems for agrochemicals to sugar cane plants, but more studies are needed to identify effect of nanoparticle exposure to health of the plant.

Topical nanodelivery system of lutein for the prevention of selenite-induced cataract

Cataracts are responsible for half of the world blindness, surgery being the only viable treatment. Lutein, a naturally occurring carotenoid in the eye, has the potential to reduce cataract progression by protecting the eye from photo-oxidative stress. To restore the eyes natural line of defense against photo-oxidative stress, a formulation was developed using zein and poly(lactic-co-glycolic acid) nanoparticles (NPs) embedded in an optimized bioadhesive thermosensitive gel for the delivery of lutein via topical application. Cataracts were induced in Crl:WI rats via selenite injection at 13 days post-partum, followed by 7 days of treatment with free lutein or lutein-loaded NPs administered orally or topically. Cataract severity was significantly reduced in rats treated with topical applications of lutein-loaded NPs compared to the positive control, while no significant differences were observed in rats treated with other lutein formulations including oral and topically applied free lutein.