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Poly(ethylene oxide) (PEO)-based polymer electrolytes are a promising class of materials for use in lithium-ion batteries due to their high ionic conductivity and flexibility. In this study, the effects of polymer architecture including linear, star, and hyperbranched and salt (lithiumbis(trifluoromethanesulfonyl)imide (LiTFSI)) concentration on the glass transition (Tg), microstructure, phase diagram, free volume, and bulk viscosity, all of which play a significant role in determining the ionic conductivity of the electrolyte, have been systematically studied for PEO-based polymer electrolytes. The branching of PEO widens the liquid phase toward lower salt concentrations, suggesting decreased crystallization and improved ion coordination. At high salt loadings, ion clustering is common for all electrolytes, yet the cluster size and distribution appear to be strongly architecture-dependent. Also, the ionic conductivity is maximized at a salt concentration of [Li/EO ≈ 0.085] for all architectures, and the highly branched polymers displayed as much as three times higher ionic conductivity (with respect to the linear analogue) for the same total molar mass. The architecture-dependent ionic conductivity is attributed to the enhanced free volume measured by positron annihilation lifetime spectroscopy. Interestingly, despite the strong architecture dependence of ionic conductivity, the salt addition in the highly branched architectures results in accelerated yet similar monomeric friction coefficients for these polymers, offering significant potential toward decoupling of conductivity from segmental dynamics of polymer electrolytes, leading to outstanding battery performance.

Polyaniline (PANI) is a promising conductive polymer for use in energy storage applications. Here, a one-step hydrothermal method of PANI polymerization on carbon felt electrode was synthesized using an azo dye, a bisulfonated dichloro anionic dye molecule to enhance an efficient textile-based flexible supercapacitor electrode material for energy storage applications. The electrode material synthesized at concentration of 2 mM AY17 exhibits 814.1 F g-1 at the scan rate of 5 mV s-1 with multiwall carbon nanotubes (MWCNTs). Due to electrostatic interaction with the polymer, the presence of high electronegativity Cl atoms in the dye molecule significantly improves the PANI structure's electron donor/acceptor properties. A symmetric supercapacitor exhibits an energy density of 11.7 W h kg−1 at a power density of 300 W kg−1, and it is 4.5 W h kg−1 at 1800 W kg−1 in 3.0 M KCl aqueous electrolyte. The capacitance retention performance value of the symmetric supercapacitor exhibited 81.76% after 2500 cycles.

Injecting hydrogen into the natural gas network to reduce CO2 emissions in the EU residential sector is considered a critical element of the zero CO2 emissions target for 2050. Burning natural gas and hydrogen mixtures has potential risks, the main one being the flame flashback phenomenon that could occur in home appliances using premixed laminar burners. In the present study, two-dimensional transient computations of laminar CH4- + air and CH4 + H-2 + air flames are performed with the open-source CFD code OpenFOAM. A finite rate chemistry based solver is used to compute reaction rates and the laminar reacting flow. Starting from a flame stabilized at the rim of a cylindrical tube burner, the inlet bulk velocity of the premixture is gradually reduced to observe flashback. The results of the present work concern the effects of wall temperature and hydrogen addition on the flashback propensity of laminar premixed methane-hydrogen-air flames. Complete sequences of flame dynamics with gradual increases of premixture velocity are investigated. At the flame flashback velocities, strong oscillations at the flame leading edge emerge, causing broken flame symmetry and finally flame flashback. The numerical results reveal that flashback tendency increase with increasing wall temperature and hydrogen addition rate. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Dye sensitized solar cells (DSSCs) are photovoltaic devices that produce electricity from the photon energy of sunlight using dyes. Dyes used DSSCs should have a broad absorption spectrum at the UV-Vis region and should be strongly bound to the photoanode surface. Dyes are used in DSSCs can be classified into three types: metal complex dyes, metal-free organic dyes and natural dyes. For metal complex dyes, ruthenium is usually used as metal centers. While most Ru complex dyes have high efficiency, Ru is a rare metal. To decrease the cost of Ru complex dyes, transition metals are widely investigated. In this work, diphenylcarbazone and tartrazine with different metal complexes were synthesized and investigated for their suitability for DSSCs. UV-Vis was used for the characterization of dyes and linear sweep voltammetry and electrochemical impedance spectroscopy were used to investigate the performance of DSSCs.

© 2023 Elsevier B.V.Because of the brain\"s complexity, developing effective treatments for neurological disorders is a formidable challenge. Research efforts to this end are advancing as in vitro systems have reached the point that they can imitate critical components of the brain\"s structure and function. Brain-on-a-chip (BoC) was first used for microfluidics-based systems with small synthetic tissues but has expanded recently to include in vitro simulation of the central nervous system (CNS). Defining the system\"s qualifying parameters may improve the BoC for the next generation of in vitro platforms. These parameters show how well a given platform solves the problems unique to in vitro CNS modeling (like recreating the brain\"s microenvironment and including essential parts like the blood-brain barrier (BBB)) and how much more value it offers than traditional cell culture systems. This review provides an overview of the practical concerns of creating and deploying BoC systems and elaborates on how these technologies might be used. Not only how advanced biosensing technologies could be integrated with BoC system but also how novel approaches will automate assays and improve point-of-care (PoC) diagnostics and accurate quantitative analyses are discussed. Key challenges providing opportunities for clinical translation of BoC in neurodegenerative disorders are also addressed.

PAAQ (Poly(2-amino-anthraquinone)) films were prepared through electrochemical oxidation of 2-amino-anthraquinone monomer in anhydrous acetonitrile using the supporting electrolyte tetrabutylammonium perchlorate. The effects of scan rate, cycle number, and monomer concentration on polymer film formation were investigated. Electrochemical detection of nitrobenzene (NB) on PAAQ modified glassy carbon electrode was examined with voltammetry and differential pulse voltammetry. The polymer-modified electrode exhibited excellent reducing ability towards NB compared to the unmodified electrode. The NB sensor developed on the polymer-modified electrode showed a wide linear response range of 0.0625 - 8 mM and a low detection limit of 2.294 mM., PAAQ (Poli(2-amino-antrakinon)) filmler, destekleyici elektrolit tetrabütilamonyum perklorat kullanılarak susuz asetonitril içinde 2-aminoantrakinon monomerinin elektrokimyasal oksidasyonu ile hazırlandı. Polimer film oluşumu üzerinde, tarama hızının, çevrim sayısının ve monomer konsantrasyonunun etkisi incelenmiştir. PAAQ ile modifiye edilmiş camsı karbon elektrot üzerinde, nitrobenzenin (NB) elektrokimyasal tespiti dönüşümlü voltametri ve diferansiyel puls voltametri ile incelendi. Polimer modifiye elektrot, modifiye edilmemiş elektrot ile karşılaştırıldığında NB'ye karşı mükemmel indirgeme yeteneği sergiledi. Polimer modifiye elektrotta geliştirilen NB sensörü, 0.0625 - 8 mM arasında geniş bir doğrusal cevap ve 2.294 mM düşük dedeksiyon limiti gösterdi.

The synthesis of the novel phthalonitrile containing (2,4,5-trimethylphenyl)ethynyl moieties was performed using the palladium-catalyzed Sonogashira crosslinking methodology. Cobalt phthalocyanine was obtained with the cyclotetramerization reaction of this dinitrile derivative, while the synthesis of zinc and manganese phthalocyanines was reported by the Sonogashira coupling reaction of the appropriate iodo phthalocyanines. Voltammetric and electrochromic analyses were applied to determine the possible applications of these complexes in different electrochemical/display technologies. The rich redox responses of the complexes had a good influence on the spectroelectrochemical characters of them. Electrochromic measurements of the complexes indicated fast, and reversible color changes with reasonable optical contrasts.

Cadmium zinc sulfoselenide, CdZnSSe, and reduced graphene oxide-cadmium zinc sulfoselenide (RGO)-CdZnSSe composite-based photoelectrodes are fabricated using a facile, simultaneous co-electrodeposition by repetitive cyclic voltammetric (rCV) for the first time in literature. With this method, CdZnSSe particles are homogeneously decorated among the RGO sheets by controlling the composition of the composite structure and the film thickness with rCV. Photoelectrochemical, optical, and structural properties of photoelectrodes are evaluated to investigate their usability in photoelectrochemical hydrogen evolution. Decorating Cd0.8Zn0.2S0.2Se0.8 among RGO sheets leads to a slight red-shift of the absorption edge because of the less transparency of fabricated photoelectrode which decreases the band gap of composites. Among all Cd0.8Zn0.2SxSe1-x (x = 0.0, 0.2, 0.5, 0.8, 1.0) photoelectrodes, Cd0.8Zn0.2S0.2Se0.8 demonstrates the sharp rise in photocurrent density (4.08 mA cm−2). Decorating Cd0.8Zn0.2S0.2Se0.8 with RGO at an optimum composition jumps the photocurrent density up to 5.00 mA cm−2 in addition to the improved stability. The long-term stability of RGO(0.25)-Cd0.8Zn0.2S0.2Se0.8 is reported as 89.8% at the end of the 48th hour. The applied bias photon to current efficiency (ABPE) and Faradaic efficiency are obtained as 3.07% and 89.9%. Enhanced photoelectrochemical performance indicates the superiority of the proposed rCV technique for the fabrication of well-controlled photoelectrodes consisting of RGO[sbnd]CdZnSSe composites.

We report the synthesis of non-peripheral metallophthalocyanines which carry four 4-(4-methoxyphenyl)-2-thiazole-2-thio units. H-1-NMR, FT-IR, UV-Vis, and MS data were acquired to characterize the synthesized compounds. Voltammetric and in situ spectroelectrochemical measurements shed light on the redox properties of the metallophthalocyanines (MPcs) in order to show the influence of the metal cations and thiazole-bearing substituents. In solution, the redox processes had an influence to the electrochromic responses, which were examined with in situ spectrocolorimetry. Phthalocyanines having cobalt (II), manganese (III), iron (III), and zinc (II) at the center yielded characteristic redox couples which are metal- and/or Pc-based and which are harmonious with the common redox properties of these types of compounds. In situ spectroelectrochemistry provided the information that MPc species underwent distinct color changes during electron transfer reactions. Electropolymerization of all complexes was performed on glassy carbon electrode, and the electropolymerized film of FePc was evaluated as an active electrocatalyst, in the alkaline medium, for oxygen evolution reaction (OER).

Elektrokromik camlar, bir elektrik akımı uygulandığında renk değişimi gösteren cihazlardır. Bu renk değişimi camın üzerine yapılan kaplamalar vasıtasıyla olur. Elektrokromik camların oluşturduğu sistem, literatürde akıllı cihazlar olarak adlandırılır. Akıllı cihazlar; cam, saydam iletken tabaka (ITO), katodik tabaka, iyon taşıyıcı, anodik tabaka, transparan iletken tabakadan oluşur. Anodik ve katodik tabakanın modifikasyonu, elektrokromik temelli uygulamaların önde gelen araştırma konularından biridir. Akıllı cihazlardaki renklenme için katodik tabakanın ve anodik tabakanın içerisine iyon giriş-çıkışı gerekmektedir. Bu tez çalışmasında; renklenen akıllı cihazların, katodik tabakasında kullanılmak üzere çeşitli oranlarda Zirkonyum (Zr) katkılanmış Tungsten Oksit (WO3) filmleri oluşturulup, bu filmlerin Li+ iyonu içeren bir sıvı elektrolit içerisindeki elektrokromik ölçümleri gerçekleştirilmiştir. Amaç, katodik tabakanın; renk değişiminin yüksek olması ve yaşam ömrünün literatürdeki diğer çalışmalara göre uzun olmasını sağlamaktır. Saydam iletken tabaka olarak kullanılan ITO elektrotlara, elektrokromik tabaka oluşturmak için farklı parametrelerde kaplamalar yapılmıştır. Magnetron sıçratma yöntemiyle %50 oksijen, %50 argon gazı olan ortamda 45 Watt (W) güçte Tungsten (W) metal hedefi kullanılarak katkısız WO3 filmi oluşturulmuştur. Ayrıca 45 W Tungsten metal hedefi ile aynı anda Zr metal hedefi 10 W, 20 W, 30 W, 40 W güçlerde yakılarak Zr:WO3 katkılı filmleri oluşturulmuştur. Bütün fimlerin kalınlıkları birbirine yakın olup yaklaşık 130 nm civarıdır. Örneklerin hepsi Taramalı Elektron Mikroskobu – Enerji Dağılım Spektrometresi (SEM-EDS) yöntemiyle karakterize edilmiştir. Yüzey ve tanecik özelliklerine taramalı elektron mikroskobu (SEM), atomik kuvvet mikroskobu (AFM), X ışını kırınımı (XRD) yöntemleri kullanılarak bakılmıştır. Elektrokromik özellikleri; Dönüşümlü voltametri (CV), Kronoamperometri (CA) ve eş zamanlı Ultraviyole – Görünür Işık (UV-Vis) Spektrofotometri yöntemleri kullanılarak belirlenmiştir. Elektrokimyasal karakterizasyon ve elektrokromik özelliklerin tayini için üç elektrotlu sistem kullanılmıştır. CV ve CA grafiklerine bakılarak filmlere iyon giriş-çıkış miktarları ve optik yoğunluklar hesaplanmıştır. Elektrokimyasal ölçümler, eş zamanlı spektroelektrokimyasal ölçümlerle (UV–Vis) birlikte değerlendirilmiş ve filmlerin geçirgenlik farkları kıyaslanmıştır. Her bir filmin yaşam ömrü belirlenip, hangi filmin kaç çevrime kadar kararlılığını koruduğu ve hangi katkılanma oranıyla hazırlanan filmin daha dayanıklı olduğu incelenmiştir. Bu sonuçların ışığında; %1,4 ve %2,8 Zr katkılama oranı ile oluşturulan filmlerin daha uzun ömürlü ve daha yüksek verimlilikte çalıştıkları gözlenmiştir. Metal oksit temelli ince filmlerinin elektrokromik açıdan incelenmesi hakkında pek çok araştırma gerçekleştirilmektedir. Manyetik sıçratma yöntemiyle elde edilen Zr katkılı WO3 filmlerin; elektrokromik özelliklerinin ve bu özelliklere farklı oranlarda katkılama etkisinin incelenmesi hakkında benzer bir çalışmaya literatürde rastlanmamıştır. Bu tez çalışmasından çıkacak sonuçlar, akıllı cihazlarda kullanılabilecek malzemelere farklı bir boyut kazandırabilir. Electrochromic glasses are devices that show color change when electric current is applied. This color change occurs through coatings applied to the glass. The system created by electrochromic glasses is referred to as smart devices in the literature. Smart devices consist of glass, transparent conductive layer (ITO), cathodic layer, ion conductor, anodic layer, and transparent conductive layer.Modification of the anodic and cathodic layers is one of the leading research topics in electrochromic-based applications. Ion intercalation and de-intercalation into the cathodic and anodic layers are required for coloration in smart devices.In this thesis study, various ratios of Zirconium (Zr)-doped Tungsten Oxide (WO3) films were grown for use in the cathodic layer of color-changing smart devices, and electrochromic measurements of these films were conducted in a liquid electrolyte containing Li+ ions. The aim was to ensure a high color change and long life time of the cathodic layer compared to other studies in the literature.ITO electrodes, used as transparent conductive layers, were coated with different parameters to create an electrochromic layer. Undoped WO3 films were created using a Tungsten (W) metal target with 45 Watts (W) growth power, the sputter consisting of 50% oxygen and 50% argon gases, using magnetron sputtering. In addition, Zr:WO3 doped films were created by simultaneously sputtering Zr metal targets with 45 W Tungsten metal target at growth power of 10 W, 20 W, 30 W, and 40 W. The thickness of all films was approximately 130 nm. All samples was characterized using Scanning Electron Microscope - Energy Dispersive Spectroscopy (SEM-EDS). Surface and particle properties were examined using scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) methods. Electrochromic properties were determined using Cyclic Voltammetry (CV), Chronoamperometry (CA), and simultaneous Ultraviolet - Visible Light (UV-Vis) Spectrophotometry methods. A three-electrode system was used for electrochemical characterization and determination of electrochromic properties. The ion intercalation/de-intercalation amounts and optical densities of the films were calculated by examining CV and CA graphs. Electrochemical measurements were evaluated along with in-situ spectroelectrochemical (UV–Vis) measurements, and the transmittance differences of the films were compared. The long life time of each film was determined. The stability of each film was investigated to determine at which cycles it remained stable and which doping ratio resulted in more durability. Based on these results, it was observed that films created with Zr doping ratios of 1,4% and 2,8% exhibited longer life time and higher efficiency. Numerous studies have been conducted on the electrochromic examination of metal oxide-based thin films.A similar study investigating the electrochromic properties of Zr-doped WO3 films obtained by magnetron sputtering and the effect of different doping ratios on these properties has not been found in the literature. The results obtained from this thesis study can provide a different dimension to materials that can be used in smart devices.

© 2022 The Authors. Published by American Chemical Society.Catalysts based on metal-free conjugated porous polymers (CPPs) are still rare for electrochemical oxygen reduction reactions (ORR). In this study, a conjugated porous polymer, TT-TPB, based on thieno[3,2-b]thiophene (TT) and triphenylbenzene (TPB), was synthesized applying palladium(0) catalyzed Suzuki coupling reaction and its ORR activity was investigated in alkaline condition. It demonstrated comparable electrocatalytic performance of ≈0.89-0.9 V Eonset vs RHE with the commercially available Pt/C. Density-functional theory (DFT) calculations revealed that TT-TPB featured efficient electrocatalytic active sites derived from volumetric, areal, and O2 adsorbing calculations, which were in line with the experimental results. Moreover, semiconducting and surface properties of TT-TPB were investigated in detail using electrochemical and spectrophotometric techniques. This work shows the potential application of thienothiophene-based metal-free CPP in the electrochemical conversion process.

© 2022 Indian Chemical SocietyThe main aim of this study is to formulate the combination of the bioactive composite containing chitosan/β -tricalcium phosphate (CH/β-TCP) as potential drug delivery platforms for the sustained release of antibiotics. Herein the mode of amoxicillin (AMX) maintained in the β-TCP/chitosan composite was characterized using XRD, FT-IR to confirm the phase purity and functional groups. SEM was used to examine the size and shape of particles. The SEM images of the biocomposites after drug release confirmed that they are biodegradable. In vitro drug release experiments in PBS (pH 7.4) revealed a sustained release profile in a neutral medium. Drug release profiles were evaluated according to five different kinetic models including Zero Order, First Order, Higuchi, Hixon Crowel, and Korsmeyer-Peppas. The release profile was best expressed by the Korsmeyer Peppas model because the results showed high linearity. Overall, the positive effect of chitosan coating on the drug elution profile of β-TCP as carriers for the controlled delivery of antibiotics was regarded as biocompatible for the controlled drug delivery system.

Food safety is a crucial issue; all countries have struggled against pesticides for years. In this study, Polypyrrole (PPy)- and Polyacrylonitrile (PAN)-based non-enzymatic electrochemical sensors were investigated to detect the pesticide propamocarb (PM) in food samples. Under the experimental conditions, the proposed strategy exhibited a high selectivity of the disposable PPy-based and PAN-based sensors for the determination of propamocarb pesticide in the concentration of 1 μM with a rapid detection within 1 min at pH 7.4 and 25 °C. We demonstrated the detection of PM residues on cucumber and tomato samples with good electrochemical performances towards the real-time usability on real food samples. PAN-based non-enzymatic electrochemical sensor has good sensitivity, higher selectivity, and stability than PPy-based non-enzymatic electrochemical sensor. The prepared PAN-based non-enzymatic electrochemical sensor is a potential candidate to be used in devices which perform food safety in agricultural products.

Zinc–nickel alloy coating (ZnNi) was successfully deposited on carbon steel (CS) applying current density of 47 mAcm-2 with galvanostatic technique. The ZnNi alloy coating image showed that CS metal surface was plated with a blue-grey homogeneous layer. Polyaniline film (PANI) film was synthesized with cyclic voltammetry technique from 0.10 M aniline containing 0.20 M sodium oxalate solution on ZnNi coated carbon steel (CS/ZnNi) electrode surface. And then the synthesis of top PPy film was achieved in pyrrole monomer containing acetonitrile + tetrabutyl ammonium perchlorate medium successfully. After the top PPy synthesis, it was observed that both the PANi homopolymer film and the ZnNi coating continued to exist on the CS surface. The corrosion behaviors of uncoated and coated electrodes were investigated in 3.5% NaCl solution. For this aim, the anodic polarization plots and electrochemical impedance spectroscopy technique were used. The results showed that the top PPy homopolymer film provided an effective barrier property on CS/ZnNi/PANi electrode and a remarkable anodic protection to substrate for longer exposure time.

Elektrot yüzeylerinin nanopartiküller ve peptitler ile kovalent olmayan immobilizasyonu, kullanılan elektrotun kimyasal özelliklerini değiştirmez, fakat hücre adezyonunun elektrokimyasal ölçümüne izin verir. Elektrot yüzeyinde nanopartikül/ peptit biyokonjugatlarının eldesi ve kanserli-normal hücre hatlarına adezyonunun elektrokimyasal olarak karşılaştırmalı izlenmesi bu doktora tezinin konusunu oluşturmaktadır. Bu bağlamda Altın nanopartiküller ile glutatyon, karnosin ve insülin benzeri büyüme faktörü-1, perde baskılı karbon elektrot yüzeyinde biyokonjugat oluşturularak immobilize edildi. Her bir peptit için modifikasyon basamaklarının karakterizasyonu Taramalı Elektron Mikroskobu-Enerji Dağılımlı X-Işını Spektrometresi (SEM-EDS) ve X-Işını Foto elektron Spektrometresi (XPS) ile gerçekleştirildi. İleri aşamada elektrot yüzeyinde üç farklı peptit ile hazırlanan hücrelere hedeflenmiş nanomalzemelerin biyofonksiyonel yüzeylerinin optimizasyonu, karakterizasyonu ve elektrokimyasal teknikler kullanılarak hücre adezyonuna verdiği cevaplar incelendi. Tez konusu kapsamında seçilen peptitler ile hazırlanan biyofonksiyonel yüzeylerin seçilen hücre hatlarının hepsine adezyon gösterdiği, altın nanopartikül/ glutatyon ve altın nanopartikül/ karnosin ile oluşturulan biyofonksiyonel yüzeylerin elektrokimyasal teknikler kullanılarak yapılan analiz sonucunun seçilen kanserli hücre hatlarının bazılarında doğrusal bir korelasyon katsayısı verdiği anlaşıldı., Non-covalent modification of electrode surfaces with nanoparticles and peptites does not change the chemical properties of the electrode used, but also allows electrochemical measurement of cell adhesion. Obtaining nanoparticle/peptite bioconjugations on the electrode surface and electrochemical comparative follow-up of their adhesion to cancerous-normal cell lines is the subject of this doctoral thesis. Glutathione with gold nanoparticle, carnosine with gold nanoparticle and insulin-like growth hormone-1 with gold nanoparticle were fixed on the screen printed carbon electrode surface by forming a bioconjugate. Scanning Electron Microscopy-Energy Dispersive X-Ray Spectrometer (SEM-EDS) and X-Ray PHotoelectron Spectrometer (XPS) were performed for the characterization of the modification steps. The main purpose of this thesis is to prepare nanomaterials targeted to cells with three different peptites on the electrode surface. Within the scope of the thesis, it was understood that the biofunctional surfaces prepared with peptites showed adhesion to the selected cell lines, and the results of the analysis of the biofunctional surfaces formed with gold nanoparticle/glutathione and gold nanoparticle/carnosine, using electrochemical techniques gave a linear correlation coefficient in some of the selected cancerous cell lines.

© 2022 Taylor & Francis Group, LLC.A simple, rapid, and precise high performance liquid chromatography (HPLC) method was developed to determine the flavonoid apigenin in cosmetic products containing chamomile extracts. A C18 column was used as stationary phase and 70:30 ethanol:water was used as mobile phase with a 1 mL/min flow rate and isocratic elution. The temperature was stabilized at 25 °C during the separation. The injection volume was 50 μL. The apigenin peak was eluted at 4.15 ± 0.4 min. The method was validated according to International Conference on Harmonisation (ICH) criteria in terms of linearity, limit of detection, limit of quantitation, selectivity, sensitivity, robustness, accuracy, and precision. The limits of detection and quantitation were 0.060 and 0.2 μg/mL respectively. The linear range was from 0.2 to 20 μg/mL. The relative standard deviation values for intraday and interday analyses were less than 1.64%. The developed procedure was applied to the analysis of various cosmetic products. It is expected that the method is suitable for routine analysis, quality control and standardization of cosmetic products for apigenin.

Bu çalışmada 3 boyutlu baskı tekniği ile elektrokimyasal biyosensör uygulamalarında kullanılmak üzere üçlü elektrot sisteminin bir parçası olan çalışma elektrotları hazırlanmıştır. Tasarlanan elektrotlar önce 3 boyutlu katı modelleme programı ile çizilip daha sonra 3 boyutlu yazıcı ile karbon siyahı/polilaktik asit (CB/PLA) bazlı filament kullanılarak üretilmiştir. Tasarlanan bu elektrotların (3DcbE) ilk önce elektrokimyasal uygulamaları saptanmasının ardından elektrokimyasal biyosensörlere uygulama çalışmaları gerçekleştirilmiştir. Çalışma kapsamında ilk olarak, modellenen elektrotların dilimleyici bir program ile G-koda dönüştürülmesinin ardından kaynaşmış birikim modellemesi (FDM) yöntemi ile çalışan bir 3 boyutlu yazıcı ile üretilmişlerdir. Çalışma elektordu kapasitelerinin araştırılması amacıyla 1 mM [Fe(CN)6]-3/-4 varlığında döngüsel (CV) ve diferansiyel puls voltametrisi (DPV) teknikler ile elektrokimyasal ölçümler alınmıştır. Farklı kalınlıklardaki iletkenlik düzeyleri ve 3 boyutlu yazıcı baskı prosedürü sırasındaki üretim kolaylığı dikkate alınarak en uygun elektrot boyutu seçilmiştir. Boyutları belirlenen elektrotların iletkenlik düzeylerini iyileştirmek adına farklı yüzey aktivasyon işlemlerine (mekanik, kimyasal, elektrokimyasal) tabi tutulmuşlardır. En uygun (kimyasal/elektrokimyasal) yüzey hazırlama tekniği saptanmasının ardından bu elektrotların iletkenlik düzeyinin iyileştirilmesi çalışmalarına devam edilmiş böylece biyosensör uygulamaları için optimizasyon işlemler tamamlanmıştır. Tüm bunların ardından elektrokimyasal DNA biyosensörlerinde sensör yüzeyi olarak kullanıma başlanmıştır. Buna yönelik yapılan ilk çalışmalarda balık sperminden elde edilmiş çift sarmal DNA (dsDNA) kullanılmış ve bu molekülün işaretsiz (label- free) olarak biyoelektronik tayinine yönelik biyosensör geliştirilmesi çalışmalarına devam edilmiştir. Bu amaçla, 3DcbE ile dsDNA'nın çözelti içinde, adsorbe yüzeyde ve kovalent bağlı yüzeylerde DPV ile ölçümleri gerçekleştirilmiştir. Bu çalışmalarda Guanin bazının elektrokimyasal sinyali (1.0V) esas alınmış ve en uygun yüzey bağlama tekniği optimize edilmiştir. 3DcbE yüzeyler ile dsDNA'nın elektrokimyasal olarak görüntülenmesinin ardından sensör yüzeylerinde kısa oligonükleotit dizileri kullanılarak hibridizasyon işlemi gerçekleştirilmiş ve DPV ile görüntülenmiştir. Hazırlanan çalışma elektrotları kullanılarak alınan ölçümler elektrokimyasal çalışmalarda sıklıkla tercih edilen tek kullanımlık kalem grafit elektrotlar (PGE) ve Perde Baskılı Elektrotlar (SPE) ile elektrokimyasal yanıt, DNA bağlama kapasitesi, LOD, LOQ, maliyet gibi parametreler esas alınarak karşılaştırmalar yapılmıştır. 3 boyutlu baskı teknolojisinin yenilikçi yönü, farklı boyutlarda hazırlanabilmesi, düşük maliyet gibi özellikleri ile yeni nesil minyatürize edilebilir biyosensörlerin geliştirilmesine olanak sağlamaktadır. Tez kapsamında tasarlanan 3DcbE elektrotlar ile hastalıkların teşhisinde son yıllarda ticari olarak geliştirilebilir, hasta başında analize uyumlu (Point of care –POC) tanı yöntem ve cihazlarının tasarımlarını mümkün kılacaktır., In this study, working electrodes, which are a part of the triple electrode system, were prepared to be used in electrochemical biosensor applications with 3D printing technique. The designed electrodes were first drawn with a 3D solid modeling program and then produced with a 3D printer using carbon black/polylactic acid (CB/PLA) based filament. After the electrochemical applications of these designed electrodes (3DcbE) were determined first, application studies were carried out on electrochemical biosensors. Within the scope of the study, firstly, after the modeled electrodes were converted to G-code with a slicer program, they were produced with a 3D printer working with the fused deposition modeling (FDM) method. In order to investigate the working electrode capacities, electrochemical measurements were taken with cyclic (CV) and differential pulse voltammetry (DPV) techniques in the presence of 1 mM [Fe(CN)6]-3/-4. The most suitable electrode size was chosen considering the conductivity levels in different thicknesses and the ease of production during the 3D printer printing procedure. In order to improve the conductivity levels of the electrodes whose sizes were determined, they were subjected to different surface activation processes (mechanical, chemical, electrochemical). After the determination of the most suitable (chemical/electrochemical) surface preparation technique, studies to improve the conductivity level of these electrodes were continued, thus optimization processes for biosensor applications were completed. After all, it started to be used as a sensor surface in electrochemical DNA biosensors. In the first studies conducted for this purpose, double-stranded DNA (dsDNA) obtained from fish sperm was used and biosensor development studies for the label-free bioelectronic determination of this molecule were continued. For this purpose, measurements of 3DcbE and dsDNA in solution, on adsorbed surfaces and on covalently bonded surfaces with DPV were carried out. In these studies, the electrochemical signal (1.0V) of the guanine base was based and the most suitable surface bonding technique was optimized. After electrochemical imaging of dsDNA with 3DcbE surfaces, hybridization was performed using short oligonucleotide sequences on the sensor surfaces and visualized with DPV. Measurements taken using the prepared working electrodes were compared with disposable graphite pencil electrodes (PGE) and Screen Printed Electrodes (SPE), which are frequently preferred in electrochemical studies, on the basis of parameters such as electrochemical response, DNA binding capacity, LOD, LOQ, cost. The innovative aspect of 3D printing technology allows the development of new generation miniaturizable biosensors with its features such as being prepared in different sizes and low cost. With the 3DcbE electrodes designed within the scope of the thesis, it will enable the designs of diagnostic methods and devices that can be developed commercially in recent years and are compatible with point of care (POC) analysis in the diagnosis of diseases.

Bu çalışmada, üç-dişli bis-benzimidazol piridin türevi ligant (L) ve bu ligantın nötr Zn(II) kompleksi [ZnLCl2] sentezlendi. Elde edilen bu yeni koordinasyon bileşiğinin yapısı aydınlatılarak, elektrokimyasal özellikleri araştırıldı. Moleküllerin yapısal karakterizasyonunda çeşitli spektroskopik yöntemler (FT-IR, 1H NMR, 13C NMR, MALDI-TOF-MS, UV-Vis gibi) kullanıldı. Elektrokimyasal özellikleri ise DMF içerisinde dönüşümlü voltametri (CV) tekniği ve kare dalga voltametrisi kullanılarak araştırıldı. Tarama hızı ve pik akımı arasındaki ilişki kullanılarak kompleksin elektrokimyasal mekanizması aydınlatılmış, kompleksin yarı-tersinir ve difüzyon kontrollü bir davranış sergilediği ortaya konulmuştur. Bu nedenle, kompleksin özellikle de redoks akışlı piller, güneş pilleri ve elektrokataliz gibi alanlarda uygulanabileceği düşünülmektedir., In this study, tridendate bis-benzimidazole pyridine derivative ligand and its neutral Zn(II) complex [ZnLCl2] were synthesized. The structure of this novel coordination compound obtained was elucidated and its electrochemical properties were investigated. In the structural characterization of the compounds were used various spectroscopic methods (such as FT-IR, 1H-NMR, 13C-NMR, MALDI-TOF-MS, UV-Vis). Its electrochemical properties were investigated in DMF using cyclic voltammetry (CV) technique. The obtained results showed that the complex exhibits quasi-reversible redox potential. Its electrochemical properties were investigated using cyclic voltammetry (CV) technique and square wave voltammetry in DMF. Using the relationship between the scanning rate and the peak current, the electrochemical mechanism of the complex was elucidated and it was lay out shown that the complex exhibits a quasi-reversible and diffusion-controlled behavior. Therefore, it is thought that the complex can be applied especially in fields such as redox flow cells, solar cells, and electrocatalysis.