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Öğe Encapsulation of lipase using magnetic fluorescent calix[4]arene derivatives; improvement of enzyme activity and stability(ELSEVIER SCIENCE BV, 2019) Ozyilmaz, Elif.; Cetinguney, Sevilay.; Yilmaz, Mustafa.In this study, iron magnetic nanoparticles capped with fluorescent calixarene derivatives (Fe3O4@Calix-2 and Fe3O4@Calix-3) were prepared in one-step using coprecipitation of Fe(II) and Fe(III) in basic solution. Different techniques were used to characterize the synthesized magnetic nanoparticles, such as Fourier Transform Infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and confocal microscopy. Candida rugosa was encapsulated on synthesized nanoparticles following sol-gel method. It has been observed that under the optimum conditions, the activity of encapsulated lipase (Fe3O4@Calix-2E) was 119 U/g of support which is 4.1 times more that of the encapsulated lipase without calix[4]arene derivative (Fe3O4@E). Comparative study show that the encapsulated lipase on nanoparticles has higher thermal and operational stability than encapsulated lipase without calix[4]arene derivative. Among these encapsulated lipase nanoparticles, Fe3O4@Calix-2 was capable of effectively catalyze hydrolysis of racemic Flurbiprofen methyl ester with high conversion of 49% and substrate enantiomeric excess (ees) of 85% at optimum pH and temperature. The efficiency of these nanoparticles was assessed by their reusability, for that after five consecutive operational uses these encapsulated lipase nanoparticles retained their conversion ratios up to 38% and 30% respectively, in the hydrolysis of (R,S)-Flurbiprofen methyl ester. The results showed that encapsulated lipases nanoparticle with calixarene moieties lead to increased activity, stability, reusability and enhanced stereoselectivity in kinetic resolution. (C) 2019 Elsevier B.V. All rights reserved.Öğe Fabrication and application of a new modified electrochemical sensor using newly synthesized calixarene-grafted MWCNTs for simultaneous determination of Cu(II) and Pb(II)(SLOVENSKO KEMIJSKO DRUSTVO, 2019) Kucukkolbasi, Semahat.; Sayin, Serkan.; Yilmaz, Mustafa.A rapid, simple, selective and highly sensitive simultaneous determination of Cu(II) and Pb(II) via newly fashioned 5,11,17,23-tetra-tert-butyl-25,27-dihydrazinamidecarb onylmethoxy-26,28- dihydroxycalix [4] arene-grafted multi-walled carbon nanotubes-modified carbon paste electrode (CNT-Calix/CPE) by differential pulse anodic stripping voltammetry (DPASV) has been introduced. It was observed that CNT-Calix/CPE exhibits higher selectivity and stability for Cu(II) and Pb(II). Different operational parameters such as pH, deposition potential/time, pulse amplitude (5, -1.0 V vs. Ag/AgCl, 300 s, 2 s, 0.05 V) were also optimized for calculation and statistical evaluation of linear range, detection limit and limit of quantification. Interference study shows that the electrode is highly selective for the simultaneous determination of Cu(II) and Pb(II). Standard addition method was used to apply CNT-Calix/CPE in waste water, plant leaves and soft drinks and it was found that the concentration of Cu(II) and Pb(II) were corresponding to standardized values.Öğe Functional group efects of new calixarene derivatives on catalytic and enantioselective behavior of lipase(TAYLOR & FRANCIS LTD, 2019) Dogan, Vildan.; Sayin, Serkan.; Uyanik, Arzu.; Yilmaz, Mustafa.In this study, two new calixarene derivatives bearing thiourea and carbamate moieties were synthesized and characterized. Moreover, thiourea- and carbamate-bridged calixarene derivatives with Fe3O4 magnetic nanoparticle were employed for the first time as the convenient additives in the encapsulation process of lipase. The results of catalytic activity and enantioselectivity of the encapsulated lipases in the hydrolysis reaction of racemic flurbiprofen methyl ester indicate that both of the encapsulated lipases (Enc-TuC[4]@Fe3O4 and Enc-CbC[4]@Fe3O4) exhibit higher conversion and enantioselectivity compared to the free-encapsulated lipase (Enc-Lipase). However, the highest affinities result was obtained when the encapsulated lipase (Enc-CbC[4]@Fe3O4) was used in the kinetic resolution reaction of racemic flurbiprofen methyl ester.Öğe Low-cost and environmentally sensitive fluorescent cellulose paper for naked-eye detection of Fe(III) in aqueous media(ELSEVIER SCI LTD, 2020) Oguz, Mehmet.; Kursunlu, Ahmed Nuri.; Yilmaz, Mustafa.The design of eco-friendly materials to detect heavy metals is today's demand to decrease pollutions in natural waters. This paper demonstrates low-cost and environmentally sensitive material for removal and detection of Fe (III) ions in polluted waters. For this, raw cellulose with powder form was firstly fabricated via immobilizing hexamethylene diisocyanate. Following the activation of cellulose, it was modified with a Bodipy for useful spectroscopic measurements to effectively detect and remove Fe(III) ion from aqueous medium. The Bodipy-based cellulose (Cell-BODIPY) exhibited exceptional performance for detecting Fe(III) ion under both long-wave light and daylight. For a better visualization in practical applications, the same modification process was also carried out for filter paper. To the best of our knowledge, this paper will inspire alternative methods in the selective detection and elimination of heavy metal ions in polluted waters.Öğe New water soluble p-sulphonatocalix[4]arene chemosensor appended with rhodamine for selective detection of Hg2+ ion(ELSEVIER, 2020) Bhatti, Asif Ali.; Oguz, Mehmet.; Yilmaz, Mustafa.In this study, we present the synthesis of water soluble calixarene appended with rhodamine (CR) at lower rim as fluorescent moiety. The synthesized water soluble fluorescent derivative was characterized with spectroscopic techniques and fluorescence response was evaluated towards Hg2+ ion in aqueous environment. Fluorescence studies shows that upon addition of Hg2+, CR induce OFF-ON behaviour which follow CHEF process. Stoichiometric data show 1:1 coordination of metal and ligand with sensitivity of 3.55 x 10(-13) molL(-1) concentration range. Selectivity of CR towards Hg2+ ion was compared in the presence of other metal ions such as Pb2+, Cu2+, Zn2+, Cr3+, Ni2+, Co2+, Al3+, Cd2+ and Fe2+. Results show that these metal ions have not pronounced effect on fluorescence intensity on CR-Hg2+ complex. (C) 2019 Published by Elsevier B.V.Öğe On/off rhodamine-BODIPY-based fluorimetric/colorimetric sensor for detection of mercury (II) in half-aqueous medium(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2019) Kursunlu, Ahmed Nuri.; Oguz, Mehmet.; Yilmaz, Mustafa.A turn on/off rhodamine-BODIPY (RB) fluorescent sensor has been designed for selective and sensitive detection of Hg (II) cation in half-aqueous solution. For this purpose, a BODIPY derivative having dual-cores is bilaterally bound to a rhodamine containing dual-amine moieties. The newly prepared sensor reacts with mercury (II) salt to generate a product with different optical parameters. These are changes confirmed by absorption, emission, and excitation measurements. A blue shift is observed as the "Turn-off" change the pink color to transparent upon the addition of Hg (II) ions which is assigned to the suppression of fluorescence resonance energy transfer upon mercury (II) ion affinity. Selectivity toward the Hg (II) ion is found to depend upon the cavity size created of the amino moieties of rhodamine and the carbonyls of BODIPY to the metal ion. The sensor RB is selective and sensitive to Hg (II) with a detection limit [1.94 (+/- 0.2) 10(-8) M]. The three-way fluorescent probe can he selectively applied for the detection of mercury (II) ion in real water samples.Öğe Synthesis and evaluation of the antitumor activity of Calix[4]arene L-proline derivatives(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2020) Oguz, Mehmet.; Gul, Alev.; Karakurt, Serdar.; Yilmaz, Mustafa.The unique conformational properties, functionality, low toxicity, and low cost make calixarene-based compounds a valuable candidate against cancer. The aim of the present study is the synthesis of the upper rim and lower rim-functionalized L-proline-based calix[4]arene derivatives and evaluation of their cytotoxic potential for human cancerous cells as well as to determine the death mechanism. Synthesized calix[4]arene (3, 8a, 8b 13a, and 13b) derivatives were characterized by different spectroscopic techniques such as (HNMR)-H-1, (CNMR)-C-13, and FTIR. In vitro effects of compounds 3, 8a, 8b, 13a and 13b were tested on human cancerous cells (HEPG2, PC-3, A-549, and DLD-1) as well as human healthy epithelium cell (PNT1A). Results show that compounds 3, 8a, 8b and 13b have cytotoxic potential on human colorectal carcinoma cells (DLD-1) with IC50, values of 43 mu M, 45.2 mu M, 64.57 mu M, and 29.35 mu M respectively. Apoptosis ratios of cell death were investigated with flow cytometer using 7-AAD and Annexin-V as markers. Cytotoxic potential of 8a was found to be higher due to increased apoptosis, when compared with healthy cells the apoptotic cell death was significantly (p < 0.0001) increased up to 1.7-fold and 2.4-fold in DLD-1 and A549 cells, respectively. In conclusion, these L-proline derived calix[4]arenes with their selective cytotoxic potential on human cancerous cells may be a potential candidate for the treatment of human CRC and lung cancer.
