Esra Bağda

Investigation of kinetic and thermodynamic characteristics of removal of tetracycline with sponge like, tannin based cryogels.

The removal of tetracycline (TC) from aqueous environment by new type of sorbents, tannin based cryogels (TAB CRGs) and control cryogels (CRGs) was studied in a batch system. The experimental parameters that affect the sorption of TC were optimized to achieve maximum removal yield. Prepared cryogels were characterized by SEM imaging, IR spectroscopy (ATR). Produced TAB cryogels have thin polymeric walls and interconnected large pores. The TAB cryogels are elastic and sponge like; its water content can easily be removed by only compressed with hand. The TAB cryogels restore their original shape and size within seconds after soaked in water. On the other, elasticity of blank CRG is lower. The Freundlich and Langmuir adsorption isotherms were conducted to deduce the mechanism of the process. The kinetics of TC adsorption was moderately fast and almost reached equilibrium in 150 min and the results followed pseudo-second-order kinetic model.

Analytical approaches for clarification of DNA-double decker phthalocyanine binding mechanism: As an alternative anticancer chemotherapeutic.

In the present study a novel water soluble double-decker phthalocyanine was synthesized and calf thymus DNA interaction of the synthesized double-decker phthalocyanine was investigated. 5-(3-pyridyl)-1,3,4-oxadiazole substituted phthalonitrile 1 was prepared by a nucleophilic displacement reaction of 4-nitrophthalonitrile with 5-(3-pyridyl)-1,3,4-oxadiazole-2-thiol. Lutetium(III) double-decker phthalocyanine 2 was prepared by cyclotetramerization of compound 1. Water soluble lutetium(III) double-decker phthalocyanine 3 was prepared with quaternarization of compound 2. The synthesized double-decker phthalocyanine and calf thymus DNA interaction was investigated with UV-vis titrimetric methods, gel electrophoresis, and viscosity measurements. The fluorometric ethidium bromide replacement assay was conducted to clarify the binding mode of water soluble double-decker phthalocyanine. The thermodynamic parameters for interaction, K, ΔG0, ΔH0 and ΔS0 were calculated between the temperature ranges of 25°C-75°C. To the best of our knowledge, this is the first study about a double-decker phthalocyanine and DNA interaction.

The feasibility of using Rosa canina galls as an effective new biosorbent for removal of methylene blue and crystal violet

Abstract In this study, removal of two cationic dyes, basic blue 9 (BB9) and basic violet 3 (BV3) with Rosa canina galls (RCG), was investigated. The parameters that affect the biosorption process such as pH of the solution, amount of biosorbent and initial dye concentration were studied. The kinetic and thermodynamic parameters of biosorption were calculated with batch systems. The optimum pH for the adsorption system was 5.0 and 7.0 for BB9 and BV3, respectively. The adsorption process followed the Freundlich model and pseudo-second-order kinetics. The maximum adsorption capacities were 107.53 mg g−1 and 312.50 mg g−1 for BB9 and BV3, respectively. The thermodynamic study indicated that the adsorptions of these cationic dyes were spontaneous and endothermic. The results show that RCG has a potential as an effective low-cost biosorbent for removal of cationic dyes.

A simple and sensitive vortex-assisted ionic liquid-dispersive microextraction and spectrophotometric determination of selenium in food samples

In the present study, a novel and eco-friendly vortex-assisted ionic liquid-based microextraction method was developed for the determination of selenium in food. The microextraction method is based on the liberation of iodine in the presence of selenium; the liberated iodine reacts with I- to form I3-. Anionic I3- reacts with cationic crystal violet dye, and the product is extracted into 1-hexyl-3-methylimidazolium hexafluorophosphate phase in the presence of Triton X-114. The proposed method is linear in the range of 2.0-70µgL-1 and has a detection limit of 9.8×10-2µgL-1. Relative standard deviations were 3.67% and 2.89% for the five replicate measurements of 14 and 35µgL-1 Se(IV), respectively. The proposed method was successfully applied to different food samples (NIST SRM 2976 mussel tissue, pepper, ginger, wheat flour, red lentil, traditional soup, cornflour, cornstarch, and garlic) after microwave digestion.

Determination of zirconium in water, dental materials and artificial saliva after surfactant assisted dispersive ionic liquid based microextraction

In this study, an extractive spectrophotometric method is proposed for the determination of trace amounts of zirconium. The method is based on the complex formation between zirconium and 2-(5-bromo-2-pyridylazo)-5-(diethylamino) phenol. Then, the formed complex is concentrated in an ionic liquid (1-hexyl-3-methylimidazolium hexafluorophosphate) phase. The parameters were optimized and analytical figures of merit were obtained. The tolerance limits for diverse ions were calculated. The enhancement factor (EF) and limit of detection (LOD) were found to be 156 and 0.012 μg L−1, respectively. The relative standard deviation (RSD) was found to be lower than 6%. The proposed method has been successfully applied to water and environmental materials.

G-quadruplex and calf thymus DNA interaction of quaternized tetra and octa pyridyloxy substituted indium (III) phthalocyanines

The interactions of small molecules with G-quadruplex and double stranded DNA are important due to their potential biological and medical usages. In the present paper, the interactions of indium (III) phthalocyanines (quaternized 2,3,9,10,16,17,23,24-octakis-[(3-pyridyloxy) phthalocyaninato] chloroindium(III): OInPc and quaternized 2(3),9(10),16(17),23(24)-tetrakis-[(3-pyridyloxy) phthalocyaninato] chloroindium(III): TInPc) with hybrid G-quadruplex (Tel 21) and parallel G-quadruplexes (nucleolin, KRAS, c-MYC, vegf) were studied. The interactions of these phthalocyanines with ctDNA were also investigated. These interactions were measured by different spectroscopic techniques such as UV-Vis, fluorescence and circular dichroism. The UV-Vis spectroscopic data treated with Benesi-Hildebrand equation and Benesi-Hildebrand constants (KBH) were calculated. These constants were found higher for octa peripheral pyridyloxy substituted phthalocyanine, OInPc. Besides, UV-Vis analysis showed that the interaction of G-quadruplexes with tetra peripheral pyridyloxy substituted phthalocyanine derivative (TInPc) resulted in removal of central indium (III) atom from the cavity of phthalocyanine macrocycle. The UV-Vis melting studies as well as fluorescence replacement techniques were also employed for clarification of mechanism. The binding mode of molecules with ct DNA was also supported with viscosity measurements. From the results, the stabilization and destabilization of G-quadruplex depending on the concentration of the OInPc and TInPc showed that these two indium (III) phthalocyanines have the potential of both the elucidation role of G-quadruplexes in gene expression and the usage in cancer therapy.