Browsing by Author "Zengin, Adem"

Now showing 1 - 20 of 61

Bentonite Grafted With Poly(n-Acryloylglycineamide) Brush: a Novel Clay-Polymer Brush Hybrid Material for the Effective Removal of Hg(Ii) and As(V) From Aqueous Environments
(Elsevier, 2021) Yilmaz, Sakir; Zengin, Adem; Sahan, Tekin
The present work was conducted to indicate bentonite grafted with poly(N-acryloylglycineamide) (PNAGA@BNT) could be applied as a novel clay-polymer brush hybrid material for the removal of Hg(II) and As(V) from aqueous environments. The PNAGA@BNT synthesized via the surface initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization method was characterized by BET analysis, Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and water contact angle measurements. Hg(II)% and As(V)% removal onto PNAGA@BNT was carried out with response surface methodology (RSM). The effects of the operating parameters, like pH, heavy metal ion concentration (C-o), PNAGA@BNT amount, and mixing time were evaluated by central composite design (CCD). The optimum Hg(II) adsorption conditions from the CCD were found to be 6.54, 24.46 mg/L, 23.98 mg, and 106.83 min for pH, C-o, PNAGA@BNT dosage, and mixing time, respectively. On the other hand, the optimum points obtained for As(V) adsorption from CCD were 4.36, 7.30 mg/L, 25.75 mg, and 83.37 min for pH, C-o, PNAGA@BNT dosage, and mixing time, in their given order. At the optimal points obtained for Hg(II) and As(V) adsorption, the maximum Hg(II)% and As(V)% removal efficiencies were 98.58 % and 90.95 %, respectively. The kinetic models with best fit were the pseudo-second-order kinetic model for Hg(II) and As(V) and Weber-Morris intraparticle diffusion was the dominant mechanism for As(V) and Hg(II). Among the isotherms, the equilibrium data best fit the Langmuir and Freundlich models for Hg(II), and the Dubinin-Radushkevich (D-R) and Freundlich models for As(V). Moreover, thermodynamic studies suggested the adsorption process was exothermic and spontaneous.
A Capillary Driven Microfluidic Chip for Sers Based Hcg Detection
(Elsevier Advanced Technology, 2022) Ahi, Elcin Ezgi; Torul, Hilal; Zengin, Adem; Sucularli, Ferah; Yildirim, Ender; Selbes, Yesim; Tamer, Ugur
In this study, a capillary driven microfluidic chip-based immunoassay was developed for the determination of Human Chorionic Gonadotropin (hCG) protein, which is prohibited by the World Anti-Doping Agency (WADA). Here, we used antibody modified magnetic metal organic framework nanoparticles (MMOFs) as a capture prob in urine sample. MMOF captured hCG was transferred in a capillary driven microfluidic chip consisting of four chambers, and the interaction of MMOF with gold nanorods labelled with 5,5'-Dithiobis-(2-nitrobenzoic acid) (DTNB) as a Raman label was carried out in the capillary driven microfluidic chip. The movement of MMOF through first chamber to the last chamber was achieved with a simple magnet. In the last chamber of capillary driven microfluidic chip, SERS signals of DTNB molecules from the sandwich complex were recorded using a Raman spectrophotometer. The selectivity of the developed method was demonstrated by applying the same procedure for the detection of Human Luteinizing Hormone (hLH), Human Chorionic Gonadotropin Hormone (hGH) and Immunoglobulin G (IgG) protein. The regression coefficient and limit of detection obtained from the standard addition method were found as 0,9985 and 0,61 IU/L, respectively. Furthermore, the conventional ELISA method confirmed that the results obtained by the presented method were acceptable with the similarity of 97.9% in terms of average recovery value, for the detection of hCG in urine samples. The analysis system developed for target proteins will be an alternative technique such as Western Blot used in routine analysis that is expensive and time consuming.
Catalytic Performance of Pd-Doped Polymer-Nanoparticle Hybrid Materials for Hydrogen Generation Through Nabh4 Hydrolysis
(Elsevier, 2025) Ecer, Uemit; Zengin, Adem; Sahan, Tekin
Creating an effective catalyst with low cost and excellent catalytic efficiency in NaBH4 hydrolysis for H2 generation will have a huge impact on the field of renewable energy. For this reason, a polymer-supported catalyst was synthesized and characterized for hydrogen generation by NaBH4 hydrolysis. For catalyst synthesis, firstly the clay (K) was given magnetic properties (Fe3O4@K.) Then, Fe3O4@K is functionalized with tannic acid (pTA@Fe3O4@K). Finally, the palladium (Pd)-doped catalyst was obtained (Pd@pTA@Fe3O4@K). The study aimed to use a time-efficient Central Composite Design (CCD) from response surface methodology (RSM) to correlate relationships between the hydrogen generation rate (HGR) and the operating parameters. Under optimum conditions (NaBH4 amount: 3.6 wt%, NaOH amount:2.77 wt%, catalyst amount: 3.29 mg/mL, and Pd loading amount:6.05 wt%), the maximum HGR value was calculated as 5891.34 mL H2/(gcat. min.). Thus, the excellently performing Pd@pTA@Fe3O4@K composite catalyst has significant potential for use in NaBH4 hydrolysis.
The Comparison of Antioxidant Capacity and Cytotoxic, Anticarcinogenic, and Genotoxic Effects of Fe@au Nanosphere Magnetic Nanoparticles
(Tubitak Scientific & Technological Research Council Turkey, 2017) Yegenoglu, Hande; Aslim, Belma; Guven, Burcu; Zengin, Adem; Boyaci, Ismail Hakki; Suludere, Zekiye; Tamer, Ugur
Magnetic gold nanoparticles are used in various biomedical, biochemistry, and biotechnology applications due to their controllable size distribution, long-term stability, reduced toxicity, and biocompatibility. Different coating materials, such as proteins, carbohydrates, lipids, and polyphenols, are applied to enhance the biocompatibility of nanoparticles. In this study, the effects of surface coatings of core-shell structured Fe@Au nanosphere magnetic nanoparticles with regard to antioxidant capacity and cytotoxic, anticarcinogenic, and genotoxic properties were investigated. The obtained results demonstrated that avidin-coated Fe@Au nanospheres had higher antioxidant capacities than uncoated nanospheres. Neither avidin-coated nor uncoated nanoparticles had a cytotoxic effect on normal cells (human gingival fibroblast cell line, HGF-1). In addition, they had anticarcinogenic effects on human cervical carcinoma (HeLa), human breast adenocarcinoma (MCF-7), and human colorectal adenocarcinoma (CCL-221). The genotoxic effects of nanoparticles were also evaluated with DNA tail damage ratio.
Construction of a Sensitive and Selective Plasmonic Biosensor for Prostate Specific Antigen by Combining Magnetic Molecularly-Imprinted Polymer and Surface-Enhanced Raman Spectroscopy
(Elsevier, 2022) Turan, Eylem; Zengin, Adem; Suludere, Zekiye; Kalkan, Nurhan Onal; Tamer, Ugur
Selective and sensitive detection of cancer biomarkers in serum samples is critical for early diagnosis of cancer. Prostate specific antigen is an important biomarker of prostate cancer, which ranks high among cancer-related deaths of men over 50 years old. Herein, a novel analytical method was introduced for detection of PSA by combining high selectivity of molecularly-imprinted polymers and high sensitivity of surface-enhanced Raman spectroscopy (SERS). Firstly, magnetic nanoparticles were grafted with an imprinted layer by using tannic acid as a functional monomer, diethylenetriamine as a cross-linker and prostate specific antigen as a template molecule. Detailed surface characterization and re-binding experiment results indicated that the imprinting of the antigen was successful with an imprinting factor of 5.58. The prepared magnetic molecularly imprinted polymers (MMIPs) were used as an antibody-free capture probe and labeled with gold nanoparticles that were modified with anti-PSA and a Raman reporter, namely 5,5'-dithiobis-(2-nitrobenzoic acid). Thus, a plasmonic structure (sandwich complex) was formed between MMIP and the SERS label. The limit of detection and limit of quantification of the designed sensor were 0.9 pg/mL and 3.2 pg/mL, respectively. The sensor also showed high recovery rates (98.0-100.1% for healthy person and 99.0-101.3% for patient) with low standard deviations (less than 4.3% for healthy person and less than 3.3% for patient) for PSA in serum samples. Compared with the traditional immunoassays, the proposed method has several advantages like low cost, reduced detection procedure, fast response, high sensitivity and selectivity. It is believed that the proposed method can be potentially used for selective and sensitive determination of tumor marker of prostate cancer in clinical applications.
Conversion From a Natural Mineral To a Novel Effective Adsorbent: Utilization of Pumice Grafted With Polymer Brush for Methylene Blue Decolorization From Aqueous Environments
(Elsevier, 2019) Yilmaz, Sakir; Zengin, Adem; Ecer, Umit; Sahan, Tekin
The present work reports the adsorption yield of methylene blue (MB) from aqueous environments using pumice (PMC) coated with poly(N-[Tris (hydroxymethyl)methyl]acrylamide), PTHAM@PMC, by surface-initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization. The synthesized PTHAM@PMC particles were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectrometry (ATR-FTIR), scanning electron microscopy (SEM) and water contact angle measurements. Results revealed that a homogeneous polymer layer was grafted on the PMC surface. Response surface methodology (RSM) with central composite design (CCD) was performed to optimize and to investigate the influence of independent parameters such as initial pH, initial MB concentration (C-o, mg/L), adsorbent dosage (m, mg), contact time (t, min) and temperature (T, degrees C) for MB% removal with PTHAM@PMC. The results based on CCD indicated that the optimum initial pH, C-o, m, t and T are 8.95, 52.53 mg/L, 40.5 mg, 67.28 min and 33.52 degrees C, respectively. The maximum removal efficiency of 98.68% and the maximum adsorption capacity of 68.998 mg/g were reached at these optimal points. Additionally, the kinetic, isotherm and thermodynamic studies were performed and the obtained results were evaluated. The great advantage of this work is that polymer brush grafted pumice had high adsorption capacity, fast adsorption kinetics, and high removal of MB. Considering all of these, it is thought that the constructed pumice with polymer brush will allow the improvement of novel procedures for the adsorption process.
Cross-Linked Poly(styrene-Co Quartz and Kaolinite Proppants for Hydraulic Fracturing Applications
(Springer Heidelberg, 2025) Akkus, Ihsan Nuri; Akinay, Yuksel; Zengin, Adem; Kazici, Hilal celik
The hydraulic fracturing operation, used as a production process in shale gas and coalbed methane reservoirs in the oil and natural gas industry, consists of fracturing fluid, proppant, and many other chemicals. This study successfully produced hydraulic fracturing proppants based on quartz and kaolinite minerals using divinyl benzene cross-linked styrene polymer with an in situ suspension polymerization method. Morphological analysis of the prepared proppants confirmed their spherical structure and the sphericity of quartz and kaolinite proppants were determined as 0.9. The polymer shells of the prepared proppants showed thermal resistance up to 375 degrees C and then decomposed between 375 degrees C and 575 degrees C. As a result of mechanical tests, quartz proppants showed a crush resistance of 14.08% under a load of 18,000 psi. Similarly, a crush resistance of 14.28% for kaolinite proppants was determined under a load of 15,000 psi. The apparent densities of quartz and kaolinite proppants were determined as 1.635 g/cm3 and 1.365 g/cm3, respectively. However, quartz proppants mostly display brittle breakage behavior, while kaolinite proppants are plastically deformed under the applied load.
Danger, Risks and Solutions Related To Call Centers: Example of Van Province
(2021) Çiçek, Hamdi; Zengin, Adem
Günümüzde gelişen teknoloji ile birlikte ülkemizde ve dünyada hızlı bir artış göstermekte olan sanayileşme, makineleşmenin de hızla artmasıyla beraber birçok sağlık ve güvenlik riskinde de artış meydana getirmektedir. Çalışanlar yaptıkları işin doğası olarak çok farklı risk faktörleriyle baş başa kalmaktadırlar. Çağrı merkezlerinde görev yapan çalışanların, çalışma saatlerinin büyük kısmını ekran önünde çalışarak geçirmesine neden olmaktadır. Bu tezde günümüzün en popüler meslek dallarından biri olan çağrı merkezlerinde karşılaşılan riskler ve bunlara yönelik çözüm önerilerinin üzerinde durulmuştur. Risk tanımlamaları yapılırken fine kinney risk analiz yöntemi kullanılmıştır. Fine kinney risk analiz yönteminde olasılık şiddet ve frekans çarpımı sonucunda ortaya çıkan risk skoruna göre risk düzeyi belirlenip bunlara uygun çözüm önerileri sunulmuştur. Tezin genel taslağı risk analizi ve literatür tarama çalışmaları üzerine inşa edilmiştir. İlerleyen teknolojiyle beraber ülkemizde ve dünya genelinde hızla artan makineleşme ile birlikte çeşitli sağlık ve güvenlik sorunlarında da artış olmuştur. Personeller yapmakta oldukları işin doğası gereği olarak çeşitli risk durumlarıyla baş başa kalmaktadırlar. Çalışanın performansına dayalı ücret şekli, ek mesailer, çalışma zamanının uzunluğu, sürekli aynı pozisyonda durma, üst üste çalan ve cevaplanmak mecburiyetinde kalınan aramalar, sürekli devam eden davranışlar, ekranlar, klavyeler, el bileği ve parmak eklemlerinde fazla zorlama, kaygı, takdir görmeme, bulunulan ortamın ısısı, aldığı ışık, nem durumu ve konfor yönünden uygun olmayışı gibi çeşitli sorunlara sebep olmaktadır ve çağrı merkezi personellerinin sağlık durumunu tehdit etmektedir.
Decolorization of Rhodamine B by Silver Nanoparticle-Loaded Magnetic Sporopollenin: Characterization and Process Optimization
(Springer Heidelberg, 2022) Ecer, Umit; Sahan, Tekin; Zengin, Adem; Gubbuk, Ilkay Hilal
Silver nanoparticles (Ag NPs) were reduced on the surface of magnetic sporopollenin (Fe3O4@SP) modified with polydopamine to enhance the degradation capability for Rhodamine B (RhB). The polydopamine-coated Fe3O4@SP (PDA@Fe3O4@SP) acts as a self-reducing agent for Ag+ ions to Ag-0. The structural properties of the synthesized nanocomposite were determined using Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS), and vibrating sample magnetometer (VSM). The systematic study of the degradation process was performed using Response Surface Methodology (RSM) to determine the relationship between the four process variables, namely, initial RhB concentration, NaBH4 amount, catalyst amount, and time. Optimum points were determined for these four parameters using both matrix and numerical optimization methods. Under optimum conditions, RhB was decolorized with a yield of 98.11%. The apparent activation energy (E-a) and rate constant (k) for the degradation were 24.13 kJ/mol and 0.77 min(-1), respectively. The reusability studies of the Ag@PDA@Fe3O4@SP exhibited more than 85% degradation ability of the dye even after five cycles. As a result, Ag@PDA@Fe3O4@SP possessed high catalytic activity, fast reduction rate, good reusability, easy separation, and simple preparation, endowing this catalyst to be used as a promising catalyst for the decolorization of dyes in aqueous solutions.
Drug Agent Substance Determination With the Shape Memory Paper in Blood Sample
(2018) Akbulut, Yeliz; Zengin, Adem
Bu çalışmada, sentetik kan örnekleri içerisinde ilaç etken madde olan propranolol tayininde kullanılmak üzere moleküler baskılanmış kağıt (Whatman No 1) yüzeyler hazırlanmıştır. Bunun için kağıt yüzeyler ilk olarak tersinir katılma-ayrılma zincir transfer (RAFT) ajanı ile modifiye edilmiştir. Ardından kağıt yüzeyler N-akriloil-L-fenilalanin (NAPAL, monomer), metilen bisakrilamit (MBAAm, çapraz bağlayıcı), propranolol (kalıp molekül), azobis isobutironitril (AIBN, başlatıcı) içeren çözeltiye konularak yüzeyde moleküler baskılama yöntemi ile baskılanmış polimerler hazırlanmıştır. Moleküler baskılanmış kağıt yüzeylere propranolol için maksimum adsorpsiyon kapasitesi 64.3 mg/g olarak belirlenmiş ve bu değere ulaşılması için optimum polimerizasyon süresi 8 saat, propranolol/NAPAL oranı 1 ve polimerizasyon sıcaklığının 60 °C olduğu sonucuna ulaşılmıştır. Kalıp molekül propranololü polimer matrisinden etkin bir şekilde uzaklaştırmak için metanol: asetik asit (5:1, v/v) karışımı en uygun çözücü karışımı olarak belirlenmiştir. Propranolol kalıp moleküler yapıca benzer moleküller (atenolol ve pindolol) ile seçicilik çalışması yapılmış ve kağıt yüzeylerin propranolol'e oldukça seçici olduğu gösterilmiştir. Moleküler baskılanmış kağıt yüzeyler kullanılarak sentetik kan içerisinde propranolol'ün oldukça yüksek geri kazanım oranlarında (% 97.0 - % 99.7) ve düşük % bağıl standart sapma (% 3.78 - % 4.92) ile tayin edilebilceği gösterilmiştir.
Dual Responsive Disposable Electrode for the Enumeration Ofescherichia Coliin Whole Blood
(Wiley-v C H verlag Gmbh, 2020) Panhwar, Sallahuddin; Ilhan, Hasan; Hassan, Syeda Sara; Zengin, Adem; Boyaci, Ismail Hakki; Tamer, Ugur
In this report, we have designed a dual responsive disposable electrode for the enumeration ofEscherichia coli K12 (E. coli K12). The immunomagnetic separation strategy provided easily bacterial detection in the whole blood. Metal-organic frameworks magnetic (MOFs) modified, and citrate capped gold nanoparticles were used as capture probe and spectro-electrochemical labels, respectively. The cyclic voltammetry (CV) was employed to quantifyE. coliwith a ranging from 10(1)to 10(7) cfu/mL with a LOD of 1 cfu/mL. The Surface enhanced Raman spectroscopy (SERS) measurements were also performed with using disposable electrode.
Effective Utilization of Fe(iii)-Based Metal Organic Framework-Coated Cellulose Paper for Highly Efficient Elimination From the Liquid Phase of Paracetamol as a Pharmaceutical Pollutant
(Elsevier, 2021) Yilmaz, Sakir; Zengin, Adem; Sahan, Tekin
This work aims to evaluate the potential utilization of Fe(III)-based metal organic framework-coated cellulose paper (MIL-100(Fe)@CP) for the elimination of paracetamol (PCM) from water systems. The characterization of MIL-100(Fe)@CP was examined with Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX). The modeling and optimization studies were examined using response surface methodology (RSM). The effects of adsorption parameters influencing PCM removal such as initial PCM concentration (C-o), pH of solution, agitation time, and adsorbent dosage were evaluated by central composite design (CCD) in RSM. For maximum PCM removal efficiency, the optimum C-o, pH, agitation time, and adsorbent dosage were 35.60 mg/L, 6.44, 167.06 min, and 16.87 mg, respectively. In these conditions, the best PCM removal efficiency was determined as 89.75%. The adsorption kinetic data for PCM were successfully expressed by the Weber-Morris and pseudo-second-order models. Moreover, the isotherm data was best fitted to the Langmuir isotherm model. All results indicate that RSM is efficient in predicting the removal efficiency of PCM onto MIL-100(Fe)@CP and the prepared novel material is a hopeful adsorbent for the highly effective elimination of pharmaceuticals such as PCM from aquatic systems. (C) 2021 Elsevier B.V. All rights reserved.
Efficient and Selective Separation of Metronidazole From Human Serum by Using Molecularly Imprinted Magnetic Nanoparticles
(Wiley-v C H verlag Gmbh, 2018) Bilici, Mustafa; Zengin, Adem; Ekmen, Elvan; Cetin, Demet; Aktas, Nahit
Magnetic molecularly imprinted nanoparticles were prepared through surface-initiated reversible addition fragmentation chain transfer polymerization by using metronidazole as a template. The molecularly imprinted magnetic nanoparticles were characterized by attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometry. The adsorption characteristics were also investigated and the kinetics of the adsorption of metronidazole on the imprinted nanoparticles were described by the second-order kinetic model with the short equilibrium adsorption time (30min). The adsorption isotherm was well matched with the Langmuir isotherm in which the maximum adsorption capacity was calculated to be 40.1mg/g. Furthermore, the imprinted magnetic nanoparticles showed good selectivity as well as reusability even after six adsorption-desorption cycles. The imprinted magnetic nanoparticles were used as a sorbent for the selective separation of metronidazole from human serum. The recoveries of metronidazole from human serum changed between 97.5 and 99.8% and showed similar sensitivity as an enzyme-linked immunoassay method. Therefore, the molecularly imprinted magnetic nanoparticles might have potential application for the selective and reliable separation of metronidazole from biological fluids in clinical applications.
Efficient Removal of 2,4-Dichlorophenoxyacetic Acid From Aqueous Medium Using Polydopamine/Polyacrylamide Co-Deposited Magnetic Sporopollenin and Optimization With Response Surface Methodology Approach
(Springer, 2023) Yilmaz, Sakir; Zengin, Adem; Sahan, Tekin; Gubbuk, Ilkay Hilal
In this study, a novel binary grafted polydopamine/polyacrylamide onto magnetic sporopollenin (PDA/PAAm@Fe3O4@SP) was synthesized in one step polymerization strategy to investigate its removal performance of 2,4-dichlorophenoxyacetic acid (2,4-D). The response surface methodology (RSM) was applied to evaluate the effects of the process factors including pH (2-8), adsorbent concentration (0.5-2 g/L), initial 2,4-D concentration (C-o) (20-80 mg/L), and contact time (30-180 min) for the 2,4-D removal performance. The central composite design (CCD) through RSM was utilized to design the experiments as well as to optimize and model the 2,4-D adsorption process. The ANOVA results clearly shows that the quadratic model (p < 0.0001) was sufficient to the best predicting of the removal performance of 2,4-D (R-2 = 0.99). The optimum conditions for the maximum 2,4-D removal (88.31%) was achieved at pH of 3.51, adsorbent concentration of 0.75 g/L, C-o of 52.85 mg/L, and contact time of 148.53 min. The adsorption kinetic was represented by both Weber-Morris (R-2 = 0.99) and pseudo-second-order models (R-2 = 0.99). The isotherm for 2,4-D completely fitted the Dubinin-Radushkevich (D-R) and Langmuir models with R-2 values of 0.98. The obtained outcomes indicated that the prepared material may be utilized as an alternative adsorbent for the removal of 2,4-D from waterbodies and the RSM method can be utilized as an eco-friendly and low-cost statistical approach for the elimination of 2,4-D.
Electrochemical Sensor Design for Selective and Sensitive Determination of Nitrite
(2022) Taneri, Burçin; Zengin, Adem; Kazıcı, Hilal Çelik
Nitrit, azot döngüsünde yan ürün olarak ve azot kaynağı olarak doğada önemli bir yere sahiptir. Dolayısıyla doğada, toprakta, suda, birçok besinde bulunmaktadır. Optimum oranda bulunan nitrit herhangi bir problem teşkil etmezken; eksikliği ya da fazla miktarda bulunması, insan sağlığı için tehlike teşkil etmektedir. Bu amaçla nitritin tayini için etkili ve güvenilir bir metodun geliştirilmesi gerekmektedir. Bu çalışma kapsamında nitrit tayini yapılması amaçlanmaktadır. Bu bağlamda ilk olarak CuMnO2 nanopartiküller sentezlenmiş ve X-Işınların Kırılması (XRD), Geçirimli Elektron Mikroskopisi (TEM), Tarama Elektron Mikroskopisi (SEM) gibi yöntemlerle karakterize edilmiştir. Daha sonra bu nanopartiküllerin elektrokimyasal nitrit tayininde kullanılabilirliği araştırılmıştır. Bununla birlikte sensörün cevap düzeyini etkilecek olan tarama hızı, ortam pH'sı, elektrot yüzeyindeki katalizör miktarı gibi parametreler optimize edilmiştir. Sensörün çalışma aralığı olarak 1-30000 µM derişim aralığı bulunmuştur. Tespit sınırı (LOD) 0.28 µM olarak tespit edilmiştir. Bununla birlikte geliştirilen yöntemin farklı su kaynaklarında nitrit tayini için uygunluğu araştırılmıştır. Yüksek geri kazanım oranları ve düşük bağıl standart sapmalar ile, önerilen yöntemin farklı su kaynaklarında nitrit tayini için uygun olduğu gösterilmiştir. Anahtar kelimeler: CuMnO2, Elektrokimya, Nitrit, Sensör
Evaluation of Material Synthesis Research Laboratories in Terms of Occupational Health and Safety: a Sample Material Synthesis Application
(2022) Yılmaz, Şakir; Zengin, Adem
Nanoteknoloji araştırmaları alanındaki çok sayıda çalışan nedeniyle sentez laboratuvarlarındaki tehlikeler ve riskler önemli bir konudur. Kantitatif veya kalitatif yöntemlerle risk değerlendirmesi, laboratuvar ortamında risklerin yönetilmesi için önemli bir yoldur. Risk değerlendirmesi, nanomalzemelerin sentezlendiği laboratuvarlarda fikir birliği sağlayan kalitatif yöntemlerle gerçekleştirilebilir. Nanoteknolojinin yükselişi, adsorpsiyon, hidrojen üretimi, sensör ve süper kapasitör gibi farklı uygulamalarla nanomalzemelerin alternatif malzemeler olarak araştırma ve ticarileştirme olanaklarını açmıştır. Ancak ölçek büyütmeden önce laboratuvar ölçeğinde sentez sürecine ilişkin genel bir tehlike tanımı yapmak gerekir. Bu çalışmanın amacı, nanomalzemelerin üretimi sırasında gerçekleştirilen deneylerin ve bu deneyler sırasında insan sağlığını etkileyen faktörlerin ve risklerin değerlendirilmesi, iş sağlığı ve güvenliği açısından değerlendirilmesidir. Bu amaçla nanomalzemelerin sentezlendiği laboratuvar ortamında örnek bir malzeme sentezi için tehlike analizleri olursa ne olur tekniği kullanılarak detaylı bir şekilde gerçekleştirilmiştir. Burada poli(2-aminoetil metakrilat)-aşılı manyetik bentonit, örnek bir malzeme sentezi olarak tartışılmaktadır. Sonuçlar, bu malzemenin sentezindeki ana tehlikelerin küçük yaralanma potansiyeli ve toksik kimyasallara maruz kalma olduğunu göstermektedir. Sonuç olarak, bu malzeme sentezinin ölçeği arttıkça, daha derin değerlendirmeler yapılması gerekmektedir ve bu çalışma gelecekte bu tür tehlikelerin belirlenmesine katkıda bulunacaktır.
Fabrication and Characterization of Poly(Tannic Acid) Coated Magnetic Clay Decorated With Cobalt Nanoparticles for Nabh4 Hydrolysis: Rsm-Ccd Based Modeling and Optimization
(Pergamon-elsevier Science Ltd, 2023) Ecer, Umit; Zengin, Adem; Sahan, Tekin
Hydrogen generation from sodium borohydride (NaBH4) hydrolysis in the presence of metal catalysts is a frequently used and encouraging method for hydrogen storage. Metal nanoparticle-supported catalysts are better recyclability and dispersion than unsupported metal catalysts. In this study, the synthesis and characterization of a polymer-supported catalyst for hydrogen generation using NaBH4 have been investigated. For the synthesis of polymeric material, first of all, kaolin (KLN) clay has been magnetically rendered by using the co-precipitation method (Fe3O4@KLN) and then coated with poly tannic acid (PTA@Fe3O4@KLN). Then, the catalyst loaded with cobalt (Co) nanoparticles have been obtained with the NaBH4 reduction method (Co@PTA@Fe3O4@KLN). The surface morphology and structural properties of the prepared catalysts have been determined using methods such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICP-MS) and vibrating sample magnetometer (VSM). The optimization of the most important variables (NaBH4 amount, NaOH amount, catalyst amount, and metal loading rate) affecting the hydrolysis of NaBH4 using the synthesized polymeric catalysts was carried out using response surface methodology (RSM). Depending on the evaluated parameters, the desired response was determined to be hydrogen production rate (HGR, mL/g min). HGR was 1540.4 mL/gcat. min. in the presence of the Co@PTA@Fe3O4@KLN at optimum points obtained via RSM (NaBH4 amount 0.34 M, NaOH amount 7.9 wt%, catalyst amount 3.84 mg/mL, and Co loading rate 6.1%). The reusability performance of the catalyst used in hydrolysis of NaBH4 was investigated under optimum conditions. It was concluded that the catalyst is quite stable.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Fabrication of Glucose Bioelectrochemical Sensor Based on Au@pd Core-Shell Supported by Carboxylated Graphene Oxide
(Academic Press inc Elsevier Science, 2023) Guler, Muhammet; Zengin, Adem; Alay, Murat
The study presents a novel electrochemical glucose biosensor based on glucose oxidase (GOx) immobilized on Au@Pd core-shell nanoparticles supported on carboxylated graphene oxide (cGO). The immobilization of GOx was achieved by cross-linking the chitosan biopolymer (CS) including Au@Pd/cGO and glutaraldehyde (GA) on a glassy carbon electrode. The analytical performance of GCE/Au@Pd/cGO-CS/GA/GOx was investigated using amperometry. The biosensor had fast response time (5.2 +/- 0.9 s), a satisfactory linear determination range between 2.0 x 10(-5) and 4.2 x 10(-3) M, and limit of detection of 10.4 mu M. The apparent Michaelis-Menten constant (K-app) was calculated as 3.04 mM. The fabricated biosensor also exhibited good repeatability, reproducibility, and storage stability. No interfering signals from dopamine, uric acid, ascorbic acid, paracetamol, folic acid, mannose, sucrose, and fructose were observed. The large electroactive surface area of carboxylated graphene oxide is a promising candidate for sensor preparation.
Fabrication of Molecularly Imprinted Cotton Fibers for Quantification of Streptomycin in Honey Samples
(Wiley, 2023) Zengin, Adem; Badak, M. Utku; Bilici, Mustafa; Aktas, Nahit
Streptomycin is a type of aminoglycoside used in treatment of several infections and with serious side effects in humans and animals, such as ototoxicity and nephrotoxicity. In the present study, we focused on the preparation of streptomycin-imprinted cotton fiber for rapid, sensitive and selective quantification of streptomycin in honey samples. The imprinted cotton fibers were characterized by attenuated total reflectance-Fourier transform spectroscopy, scanning electron microscopy, and x-ray photoelectron spectroscopy. In addition, the imprinted cotton fibers showed high adsorption capacity (95.4 mg/g) with an imprinting factor of 3.69 and had satisfactory regeneration ability of up to 10 regenerations without significant change in adsorption capacity. The imprinted cotton fibers showed good linearity with a correlation coefficient of 0.9989 and limit of detection was determined to be 0.29 ng/mL for streptomycin in honey samples. The proposed method showed acceptable recovery ranges (98.0%-100.3%) with lower inter-day and intra-day precisions. Moreover, the performance of the proposed method was compared to the ELISA method. The results showed that the present method is as sensitive and selective as ELISA. It is concluded that the imprinted cotton fibers could be a potential alternative to antibiotic quantification based on traditional immunoassays or chromatographic techniques.
Facile Synthesis of Molecularly-Imprinted Magnetic-Mos2 Nanosheets for Selective and Sensitive Detection of Ametryn
(Elsevier, 2025) Bilici, Mustafa; Zengin, Adem
In the present study, a novel analytical method was developed for selective and sensitive detection of ametryn in tap and lake water samples based on molecular imprinting technology with high performance liquid chromatography-ultraviolet detection. For this purpose, molecularly-imprinted magnetic MoS2 (MIP@magMoS2) particles were synthesized via surface initiated reversible addition-fragmentation chain transfer polymerization. The investigation of the rebinding properties, selective recognition ability, and reusability of the MIP@mag-MoS2 demonstrated their high adsorption capacity, outstanding selectivity, rapid adsorption kinetics, and capability for multiple uses, with an imprinting factor of 4.39. The detection limits for ametryn were 0.031 mu g/L and 0.041 mu g/L in tap water and lake water, respectively. The proposed method also had high recovery percentage and low relative standard deviations for the water samples spiked with ametryn. The results suggest that the combination of mag-MoS2 with MIP layer is a prospective alternative analytical method for quantification of ametryn.