Browsing by Author "Kassa, Solomon Bezabeh"

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    A reaction-based carbazole-dicyanovinyl conjugated colorimetric and ratiometric fluorescent probe for selective detection of cyanide ions
    (Pergamon-Elsevier Science Ltd, 2023-09-07) Battal, Ahmet; Kassa, Solomon Bezabeh; Gültekin, Nuray Altınolçek; Tavaslı, Mustafa; Onganer, Yavuz; ALTINÖLÇEK GÜLTEKİN, NURAY; TAVASLI, MUSTAFA; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; 0000-0002-9466-1111 ; HNL-5314-2023; AAB-1630-2020
    In the present work, 4-(9'-hexylcarbazol-3'-yl)benzylidenemalononitrile 5 (probe L) was tested as a colorimetric and ratiometric fluorescent probe in dimethyl sulfoxide (DMSO) medium towards anions, cations and neutral molecules. The sensing properties of probe L were investigated by using UV-Vis absorption and fluorescence spectroscopy techniques. Probe L showed selectivity and sensitivity towards cyanide ions (CN-) in the presence of analytes used. Upon the addition of CN-, intramolecular charge transfer (ICT) band at 425 nm in UV spectrum disappeared. In addition, ICT emission intensity at 593 nm decreased and ligand-centred (LC) emission intensity at 480 nm increased. These findings indicate that nucleophilic conjugate addition of CN- to the dicyanovinyl group of probe L successfully occurs, hence forming a new adduct between probe L and CN-. In this adduct, pi-conjugation was partially blocked, and the ICT transfer was hindered. Adduct formation was proved by Job's plot, H-1 NMR and FT-IR analysis. Probe L showed very low limit of detection (LOD) value of 1.467 nM towards CN-. Probe L was also applied to the CN- detection in real-world water samples by the spike and recovery method. The maximum relative standard deviation (RSD) value was 4.24, indicating this method works successfully. Therefore, probe L could find a potential use in detection of CN- in liquid media.
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    Effects of some phenolic compounds on the inhibition of α-glycosidase enzyme-immobilized on Pluronic®F127 micelles: An in vitro and in silico study
    (Elsevier, 2021-10-28) Kassa, Solomon Bezabeh; Taslimi, Parham; Özel, Şahin; Gür, Bahri; Gülçin, İlhami; Önganer, Yavuz; ÖZEL, ŞAHİN; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; JHC-0846-2023
    This study aimed to consider the activity of immobilized alpha-glycosidase, significant enzyme defined in serum glucose adjustment, on Pluronic (R) F127 micelles and to compare the results with theoretical molecular docking studies. The phenolic molecules were used for the activity studies, which play a crucial role in the inhibition of alpha-glycosidase by providing conservation against pathogen factors. The immobilization of alpha-glycosidase on Pluronic (R) F127 micelles showed higher kinetic activity towards p-nitrophenyl-D-glucopyranoside (pNPG) than the free one. The inhibition profiles from some phenolic molecules were observed impressively with IC50 values between 20.47 and 1118.68 nM and K-i values between 18.51 and 1087.53 nM against immobilized alpha-glycosidase. In addition, the inhibition effects of the studied phenolic compounds have been tested with calculated negative binding energies from theoretical molecular docking studies. Negative binding energy values were as - 6.1 and - 8.3 kcalmol(-1) for p-coumaric acid and tetrakis compounds, respectively.