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  • Küçük Resim
    Öğe
    Polisakkarit-kriyojel temelli elektrokimyasal biyosensör geliştirilmesi ve uygulamaları
    (Ege Üniversitesi, 2023) Tunca, Nilay; Erdem Gürsan, Kadriye Arzum; Bütün Şengel, Sultan
    Tez çalışmamızda, kriyojellerin ve iletken polimerlerin üstün özelliklerinden yararlanılarak bir polisakkarit- kriyojel temelli elektrokimyasal DNA biyonsensörü geliştirilmiştir. Çalışma elektrodu olarak kullanılan 2B kalem grafit elektrotlar polipirol iletken kriyojelleri ile modifiye edilmiştir. Kriyojel sentezinde, karragenan (KG) ve sodyum aljinat (SA) doğal polimerleri kullanılmıştır. Elektron transferini arttırmak amacıyla yapıya polipirol iletken polimeri dahil edilmiştir. Modifikasyonda kullanılan kriyojeller termogravimetrik analiz (TGA) Fourier dönüşümlü spektroskopisi (FTIR) ve taramalı elektron mikroskobu (SEM) ile karakterize edilmiştir. Elektrot yüzeylerinin karakterizasyonu ise enerji dağıtıcı X-ray analizi (EDX) ile gerçekleştirilmiştir. Modifiye elektrotlar dönüşümlü voltametri (CV) ve elektrokimyasal empedans spektroskopisi (EIS) teknikleri kullanılarak karakterize edilmiştir. Elektrot yüzeyine DNA immobilizasyonunu takiben voltametrik analiz gerçekleştirilmiştir. Ara destek malzemesi olarak kullanılan iletken kriyojellerin geniş yüzey alanı sayesinde DNA immobilizasyonu kapasitesinin arttığı görülmüştür. Yapıya dahil edilen polipirol iletken polimeri ile elektron transfer hızının arttığı tespit edilmiştir. Tez kapsamında, elektrokimyasal DNA tayinine yönelik, kolay hazırlanabilir, duyarlı ve maliyeti düşük tek kullanımlık analiz platformları geliştirilmiştir.
  • Küçük Resim Yok
    Öğe
    SMART MATERIALS AND THEIR ADVANCED BIOMEDICAL APPLICATIONS: HNT AND HNT-POLYMER COMPOSITES
    (2023) Şengel, Sultan Bütün; Tunca, Nilay; Deveci, Hatice; Baş, Harun; Bütün, Vural
    The aluminosilicate clay minerals (Al2Si2O5(OH)4·nH2O) known to exist in nature are called halloysite nanotubes (HNTs). HNTs, which are found in layered, spherical, flat and other forms, can be obtained naturally as well as synthetically. HNTs with an outer diameter of 50 nm and a length ranging from 500 to 1000 nm have a hollow and nanotube-shaped structure. It has natural deposits in Brazil, Turkey, New Zealand, China, the United States, Korea, Japan, and France, and it is a low-cost material that can be obtained through ore purification. Thanks to their high surface area, large pore volume, rheological properties, high interactions, and high binding capacities with biopolymers, HNTs are used in a wide range of areas. For example, HNTs have become a frequently used material in environmental applications such as wastewater treatment and removal of organic contaminants and dyes. It is also used in the production of nanoelectronics and nanocomposites, catalytic studies, flame retardants in make-up materials, forensic sciences and biomedical fields. The specific properties of HNT used in the biomedical field lead to numerous applications. In this review, it is aimed to present the advantages of HNTs for use in drug delivery systems, immune therapy, anti-infection applications, cancer therapy, bioimaging, biosensing applications, tissue engineering applications, implants and hygiene-cosmetics materials.
  • Küçük Resim Yok
    Öğe
    Synthesis and characterization of polysaccharide-cryogel and its application to the electrochemical detection of DNA
    (Springer Wien, 2024) Tunca, Nilay; Maral, Meltem; Yildiz, Esma; Sengel, Sultan Butun; Erdem, Arzum
    The main goal of our study is to demonstrate the applicability of the PPy-cryogel-modified electrodes for electrochemical detection of DNA. First, a polysaccharide-based cryogel was synthesized. This cryogel was then used as a template for chemical polypyrrole synthesis. This prepared polysaccharide-based conductive cryogel was used for electrochemical biosensing on DNA. Carrageenan (CG) and sodium alginate (SA) polysaccharides, which stand out as biocompatible materials, were used in cryogel synthesis. Electron transfer was accelerated by polypyrrole (PPy) synthesized in cryogel networks. A 2B pencil graphite electrode with a diameter of 2.00 mm was used as a working electrode. The prepared polysaccharide solution was dropped onto a working electrode as a support material to improve the immobilization capacity of biomolecules and frozen to complete the cryogelation step. PPy synthesis was performed on the electrodes whose cryogelation process was completed. In addition, the structures of cryogels synthesized on the electrode surface were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Surface characterization of the modified electrodes was performed by energy-dispersive X-ray spectroscopy (EDX) analysis. Electrochemical determination of fish sperm DNA (fsDNA) was performed using a PPy-cryogel-modified electrode. The use of a porous 3D cryogel intermediate material enhanced the signal by providing a large surface area for the synthesis of PPy and increasing the biomolecule immobilization capacity. The detection limit was 0.98 mu g mL(-1) in the fsDNA concentration range 2.5-20 mu g mL(-1). The sensitivity of the DNA biosensor was estimated to 14.8 mu A mM(-1) cm(-2). The stability of the biosensor under certain storage conditions was examined and observed to remain 66.95% up to 45 days.