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Öğe Bazı Antidepresan ve Antiepileptik İlaçların İnsan Kanında Eş Zamanlı Analizi için LC-MS/MS Yöntemi Geliştirilmesi(2019) Temel, Mehmet Kamil; Aksu, Osman; Kaya, Ertuğrul; Dönmez, Mert; Ergun, ÜmitBu çalışmada, sık kullanılan antidepresan ilaç etken maddeleri olan Paroksetin, Sitolapram, Essitolapram,Venlafaksin ile antiepileptik ilaç etken maddeleri olan Karbamazepin ve Oxkarbamazepin moleküllerinin tayiniiçin, insan kanında Sıvı Kromatografisi-Kütle Spektrometresi (LC-MS/MS) cihazı ile basit, hızlı ve güvenilirolan bir metot geliştirilmiştir. Her bir ilaç etken maddesi için geri kazanım, doğruluk, yüzde bağıl standart sapma(%RSD), gözlenebilme sınırı (LOD) ve alt tayin sınırı (LOQ) gibi bazı analitik parametrelerin belirlenip,ölçülebilir en düşük değerlerin yüksek hassasiyet ile en kısa sürede eş zamanlı olarak yapılması amaçlanmıştır.Etken maddelerin her biri için belirlenen konsantrasyonlarda; LOD değerleri 0,06-0,36 ng.mL-1, LOQ değerleriise 0,21-1,21 ng.mL-1aralığında elde edilmiştir. Gün içi tekrarlanabilirlik değerlerinde %RSD sonuçları 0,15-10,71 ng.mL-1, günler arası tekrarlanabilirlik değerlerinde ise %RSD sonuçları 0,23-13,75 ng.mL-1 aralığındabulunmuştur.Öğe Comparison of Chemical Contents of Extracts in Different Solvents of Propolis Samples Produced in Duzce Province(Düzce Üniversitesi, 2020) Dönmez, Mert; Karadeniz, Şeref; Yoldas, Taner; Aydın, Gülşah; Karagül, Pınar; Aksu, Osman; Göç Rasgele, PınarObjective: Although the volatile components in the propolis composition are in very low concentration, they are extremely important for the characterization of propolis due to their aroma-giving properties and various biological activities. Since propolis is a product obtained from plants, its chemical composition depends on the local plant flora and the geographical and climatic characteristics of the region where the sample is collected. Therefore, different propolis samples can differ completely in terms of their chemistry and biological activities. Propolis extracts obtained by using different solvents have different contents. For this reason, the content of antioxidants varies, which causes differences in phenolic and flavonoid amounts. In the study, it was aimed to determine the efficacy of different propolis extracts produced as a result of beekeeping activities in Düzce province by comparing the chemical content. Material-Method: The extracts of propolis collected from Düzce province were prepared using ethanol, water and PEG400 – water solvents. In the study carried out, the volatile components of three different extracts of propolis samples obtained from hives belonging to Yığılca Region were examined with LC-MS/MS, GC-MS UV. The determination of the total phenolic component (TPC) level was carried out with the Folin-Ciocalteu reagent, and the total flavonoid content (TFC) level with the AlCl3 based method.Results: Major volatile constituents of Ethanolic extract; Diphenyl-1,2,5-oxadiazole (86.11%) and Benzenepropanoic acid ethyl ester (6.3%), Major volatile components of PEG400-water (50% - 50%) extract; 4-vinyl-2-methoxy-phenol (40.40%), Benzyl benzoate (17.16%), Methyl benzyl ketone (16.87%) ve Ethyl 3-methylnaphtho[1,2-c]pyrrole-1-carboxylate (14.32%), major volatile components of water extract; Benzyl Alcohol (79.91%) ve 4-vinyl-2-methoxy-phenol (8.86%). The highest TPC level was in ethanolic extract with 23,192.45 ± 396.54 mgGAE/100 g. Similarly, the highest TFC was found in ethanolic extract (7,190.12 ± 203.85 mgQE/100g). The water extract had the lowest levels at both TPC and TFC levels.Conclusion: It has been concluded that the highest phenolic content of propolis, which has recently begun to find an important use in the food and health sector, is obtained by ethanol extraction. When evaluated in terms of the obtained results from all methods, it is listed as Etanolic extract> PEG400> water extract. Further studies should be done using different solvents in order to extract as much of the components from propolis as possible.Öğe Fluorescent detection of dipicolinic acid as a biomarker of bacterial spores using lanthanide-chelated gold nanoparticles(Elsevier Science Bv, 2017) Dönmez, Mert; Yılmaz, M. Deniz; Kılbaş, BenanGold nanoparticles (GNPs) functionalized with ethylenediamine-lanthanide complexes (Eu-GNPs and Tb-GNPs) were usedfor the selective fluorescent detection of dipicolinic acid (DPA), a unique biomarker of bacterial spores, in water. Particles were characterized by transmission electron microscopy and zeta potential measurements. The coordination of DPA to the lanthanides resulted in the enhancement of the fluorescence. A selective response to DPA was observed over the nonselective binding of aromatic ligands. The ligand displacement strategy were also employed for the ratiometric fluorescent detection of DPA. 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedion (TFNB) was chosen as an antenna to synthesize ternary complexes. The addition of DPA on EuGNP:TENB ternary complex quenched the initial emission of the complex at 615 nm and increased the TFNB emission at 450 nm when excited at 350 nm. The results demonstrated that the ratiometric fluorescent detection of DPA was achieved by ligand displacement strategy. (C) 2016 Elsevier B.V. All rights reserved.Öğe Ratiometric fluorescence detection of an anthrax biomarker with Eu3+-chelated chitosan biopolymers(Elsevier Sci Ltd, 2018) Dönmez, Mert; Öktem, Hüseyin Avni; Yılmaz, M. DenizA novel chitosan-based ratiometric fluorescent probe incorporating an EDTA-Eu3+ complex as the sensing unit and fluorescein dye as the internal standard was designed to detect dipicolinic acid (DPA) as an anthrax bio-marker with high sensitivity and selectivity. The fluorescence intensity of fluorescein dye attached to the chitosan backbone remains constant as an internal reference, while the Eu3+ emission increased linearly upon the consecutive addition of DPA. The selectivity studies were performed by adding different competitive aromatic ligands to the sensing environment and no signifacant fluorescence response was observed. The results demonstrated the superior selectivity of the system to DPA. Overall, this novel chitosan-based ratiometric fluorescent probe enables ratiometric and sensitive DPA detection over nanomolar concentrations (as low as 10 nM) and displays straightforward selectivity over other competitive aromatic ligands.Öğe Separating Mad Honey from Other Honeys with Grayanotoxin Analysis in LC-MS/MS(Düzce Üniversitesi, 2020) Dönmez, Mert; Kaya, ErtuğrulObjective: Honey samples were collected from 82 different pieces during the season when rhododendron flowers bloomed in Duzce areas in 2017. Since the majority of these honeys collected are sold as mad honey by local people, has been determined that it is the most suitable period to make their analysis.Material-Method: To apply our sample preparation method, honey samples were prepared to be analyzed on the LC-MS/MS. The accuracy, repeatability and reliability of the analysis method were provided by us. Results: The obtained results were calculated with the calibration plot drawn at ppb (ng/ml) level in LC-MS/MS. The grayanotoxin -III levels in mad honey were found to be % 36 for 0 ng/ml, %43 for 0.5-10 ng/ml, %15 for 10-50 ng/ml and %6 for 50? ng/ml.Conclusion: Most of honey samples do not contain toxins. Some of them are safe to use in middle proportions and less of them dangerous to consume.Öğe Terbiyum/europiyum şelatlı altın nanoparçacıklar kullanarak dipikolinik asidin floresans yöntemi ile belirlenmesi(Düzce Üniversitesi, 2016) Dönmez, Mert; Kılbaş, BenanBakteri sporları en zor yaşam koşullarında bile hayatlarını sürdürebilen organizmalardır. Özellikle patojen bakterilerin sporları sağlık, gıda, biyoterörizm ve uzay araştırmaları gibi birçok alanda dikkat edilmesi gereken türlerdir. Bunların tehlike sınırlarının altında belirlenmesi ve miktarlarının tayini oldukça önemlidir. Floresans sensörler, floresans olmayan iyonların ya da biyomoleküllerin tespitinde oldukça sık kullanılmaktadır. Bu metod, floresans ışık yayan moleküllerin kovalent olmayan etkileşimlerle iyonlara veya biyomoleküllere bağlanması ile birlikte molekülün spektral özelliklerinin değişmesi prensibine dayanır. Lantanit iyonu bazlı floresans spektroskopisi, lantanitlerin üstün özelliklerinden dolayı son yıllarda büyük ilgi görmektedir. Nanoparçacıklar, son yıllarda boyutlarına bağlı optik, elektriksel, fiziksel ve kimyasal özellikleri nedeniyle sensör ve ilaç taşınım/salınım uygulamalarında oldukça fazla kullanılmaktadırlar. Bu anlamda birçok nanoteknolojik yapı olmasına rag?men altın nanopartiküller çok özel bir yer tutmaktadır. Bu çalışmada, modüler bir nanosensör sistemi oluşturarak istenilen dalga boyunda belirleme yöntemi geliştirip hızlı, kolay ve ucuz bir şekilde, patojenik bakteri sporlarında bulunan dipikolinik asidin, floresans özellikleri olan nanosensörler aracılığıyla belirlenmesi ve miktarının tayin edilmesi sağlanmıştır. Böylece analitik olarak belirleme ortamına bir iç standart ekleme işlemi ortadan kaldırılıp, kendi kendine kalibre olan, yüksek belirleme hassasiyetinde bir nanosensör sistemi oluşturulmuştur.
