L-FenilalaninIn Tanınmasına Yönelik Afinite Kartuşlarının Hazırlanması

Affinity chromatography is a chromatographic method of separating biological mixtures, based on highly specific biological interactions. Hydrophobic interaction chromatography, (HIC), which is a sub-group of affinity chromatography, takes advantage of the hydrophobicity of proteins promoting its separation on the basis of hydrophobic interactions between immobilized hydrophobic ligands and nonpolar regions on the surface of the proteins. L-Phenylalanine (L-Phe) is a hydrophobic amino acid and the central nervous system requires it for normal operation. L-Phe is used in medicine, pharmaceutical and food industry. Enantiomers have the same chemical or physical properties, but different biological, pharmacological and toxicological effects due to differences such as the nature of different biological and pharmacological activity.Afinite kromatografisi, biyolojik karışımların ayrımında ve tanınmasında kullanılan yüksek seçicilikte kimyasal etkileşimlere dayanan kromatografik bir yöntemdir. Afinite kromatografisinin bir alt grubu olan hidrofobik etkileşim kromatografisi (HEK), proteinlerin ve aminoasitlerin yapısında bulunan polar olmayan bölgeler ile hidrofobik ligandlar arasında gerçekleşen, hidrofobik etkileşimleri temel alan kromatografik bir yöntemdir. Bu yöntem, proteinlerin ve aminoasitlerin hidrofobik bölgelerinden tanınmasını hedef alır. Hidrofobik bir amino asit olan L-fenilalanin (L-Phe), merkezi sinir sisteminin normal çalışması için gereklidir. L-Phe; sağlık, ilaç ve yiyecek endüstrisinde kullanılmaktadır. Enantiyomerler; aynı kimyasal veya fiziksel özelliklere sahip fakat biyolojik, farmakolojik ve toksikolojik etkileri gibi önemli farklılıklarından dolayı farklı biyolojik doğaya ve farmakolojik aktivitelere sahiptirler

Yüzey Plazmon Rezonans (SPR) Temelli Aflatoksin Sensörlerin Hazırlanması

Mycotoxins are toxic metabolites produced by various groups of fungi that pollute different types of agricultural products before and after harvest storage. Aflatoxins (AFs) are mycotoxins that harm human and animal health. AFs are highly toxic and carcinogenic secondary metabolites that are naturally produced by fungi species, especially Aspergillus flavus and Aspergillus parasiticus. AFs display mutagenic, teratogenic and highly hepatotoxic and hepatocarcinogenic effects. It is categorized as a Group I carcinogen by the International Agency for Research on Cancer (IARC). AFs are divided into various types; aflatoxin B1, B2, M1 and M2. Aflatoxin B1 (AFB1) is very common in agricultural products and has the highest toxicity among aflatoxins. Aflatoxin M1 (AFM1), the hydroxylated metabolite of AFB1, is found in animal tissues and liquids (milk and urine). Due to their extremely high toxicity and carcinogenicity, control of maximum aflatoxin residue levels in foodstuffs is carried out by many countries. Aflatoxins are high risk mycotoxins and therefore significant research should be conducted on a wide variety of analytical and high-precision assay techniques that can be useful and practical. Label free optical biosensors are an interesting option for the detection of many analytes because they offer several advantages such as high sensitivity, direct and real-time measurement. Since sensor response is related to the size of the analyte, immobilization strategies have recently been developed to overcome some limitations in this area by designing label free optical sensors for small molecules. The surface plasmon resonance (SPR) sensor system is a powerful optical-based tool for monitoring biomolecular interactions. SPR-based biosensors are widely used to simple and directly detection biospecific interactions in real time without chemical labeling. Molecular imprinting technology was first proposed by Wulff and Sarhan in 1972. The technology includes polymerization around a template molecule followed by removal of the template from the respective matrices to leave selective recognition sites. Molecularly imprinted polymers have been used in many scientific and technical fields as molecular recognition materials due to their stability, cost effective, high affinity and superior substrate recognition capabilities and ease of preparation. In this thesis, molecularly imprinted based surface plasmon resonance (SPR) nanosensors have been prepared for fast and sensitive detection of AFB1 and AFM1 in food. A sensitive and selectively imprinted optical sensor for the detection of AFB1 and AFM1 was prepared by embedding modification of gold nanoparticles (AuNPs) on the gold chip surface and designing a thin imprinted polymer film. Low molecular weight mycotoxins were detected by enhanced the sensitivity of the polymer film conjugated with gold nanoparticles. N-methacryloyl-L-phenylalanine (MAPA) as a functional monomer is utilized in the polymer film based on poly(2-hydroxyethyl methacrylate). The effectiveness of the gold nanoparticles amplification strategy is discussed. Highly sensitive detection of AFB1 and AFM1 in milk for ~8 minutes analysis time was performed in the SPR nanosensor. The detection limit (LOD) values determined for AFB1 and AFM1 were 1.04 pg.mL-1 and 0.4 pg.mL-1, respectively. Also, AFB1 determination was carried out in corn and peanut samples contaminated with AFB1. In a random dairy farmer milk and raw milk samples, AFM1 determination was performed. Repeatability and storage stability of the aflatoxin imprinted sensors were investigated. The polymer film of the designed chips was calculated using Scatchard, Langmuir, Freundlich and Langmuir-Freundlich adsorption isotherms to determine the surface homogeneity. Adsorption behavior in both AFB1 and AFM1 imprinted nanofilm-coated chips was found to fit with the Langmuir model.Mikotoksinler, hasattan önce veya hasat sonrası depolama sırasında ve farklı türlerde tarımsal ürünleri kirleten çeşitli mantar grupları tarafından üretilen toksik metabolitlerdir. Aflatoksinler (AF) insan ve hayvan sağlığı üzerinde zararlı etkiye sahip mikotoksinlerdir. Aflatoksinler özellikle Aspergillus flavus ve Aspergillus parasiticus mantar türleri tarafından doğal olarak üretilen oldukça zehirli ve kanserojen ikincil metabolitlerdir. Aflatoksinler mutajenik, teratojenik ve son derece hepatotoksik ve hepatokarsinojenik etkiler gösterirler. Uluslararası kanser araştırma ajansı tarafından Grup 1 kansorejenler olarak sınıflandırılmıştır. Aflatoksinler çeşitli tiplere ayrılır; aflatoksin B1, B2, M1 ve M2. Aflatoksin B1 (AFB1) tarım ürünlerinde oldukça yaygın olarak bulunur ve aflatoksinler arasında en yüksek toksisiteye sahiptir. AFB1’in hidroksilenmiş metaboliti olan Aflatoksin M1 (AFM1), hayvansal dokularda ve sıvılarda (süt ve idrar) bulunur. Son derece yüksek toksisiteleri ve kanserojen olmaları nedeniyle, gıda maddelerinde maksimum aflatoksin kalıntı seviyeleri kontrolü birçok ülke tarafından yürütülmektedir. Aflatoksinler büyük risk taşıyan mikotoksinlerdir ve bu nedenle faydalı ve pratik olabilecek çok çeşitli analitik ve yüksek hassasiyetli tayin teknikleri hakkında önemli araştırmalar yapılmalıdır. Etiketsiz optik biyosensörler yüksek hassasiyet, doğrudan ve gerçek zamanlı ölçüm gibi çeşitli avantajlar sağladıkları için birçok analitin analizi için ilgi çekici bir seçenektir. Sensör tepkisi analitin büyüklüğü ile ilgili olduğundan küçük moleküller için etiketsiz optik sensörlerin tasarlanması ile bu alandaki bazı sınırlamaların üstesinden gelmek için son zamanlarda immobilizasyon stratejileri geliştirilmiştir. Yüzey plazmon rezonans (SPR) sensör sistemi biyomoleküler etkileşimlerin izlemesinde kullanılan optik temelli güçlü bir araçtır. Biyospesifik etkileşimleri doğrudan ve basit bir şekilde kimyasal etiketleme olmadan gerçek zamanlı olarak hassasiyetle ölçmek için SPR temelli biyosensörler yaygın olarak kullanılmaktadır. Moleküler baskılama teknolojisi ilk olarak 1972'de Wulff ve Sarhan tarafından ileri sürülmüştür. Teknoloji, bir kalıp molekül etrafında polimerizasyonu ve ardından seçici tanıma bölgelerini bırakmak için kalıp molekülün ilgili matrislerden uzaklaştırılmasını içermektedir. Moleküler baskılanmış polimerler, kararlılıkları, düşük maliyetleri, yüksek afiniteleri ve üstün substrat tanıma yetenekleri ve hazırlanma kolaylığı nedeniyle, birçok bilimsel ve teknik alanda moleküler tanıma materyalleri olarak kullanılmıştır. Sunulan tez çalışmasında, AFB1 ve AFM1’in gıdalarda hızlı ve hassas tayini için moleküler baskılama temelli yüzey plazmon rezonans (SPR) nanosensörler hazırlanmıştır. AFB1 ve AFM1 tayini için hassas ve seçici baskılanmış bir optik sensör, altın çip yüzeyinde altın nanopartiküllerin (AuNP'ler) gömülü olarak modifikasyonu ve ince bir baskılanmış polimer film tasarlanarak hazırlanmıştır. Düşük molekül ağırlığına sahip mikotoksinler altın nanopartiküller ile konjuge edilmiş polimer filmin duyarlılığı artırılarak tayin edilmiştir. Poly(2-hidroksietil metakrilat) temelli polimer filmde N-metakriloil-L-fenilalanin (MAPA) fonksiyonel monomer olarak kullanılmıştır. Altın nanopartikül amplifikasyon stratejisinin etkinliği tartışılmıştır. SPR nanosensörde tarım ürünlerinde AFB1 ve sütteki AFM1'in ~8 dakika analiz süresiyle çok hassas bir şekilde tayini gerçekleştirilmiştir. AFB1 ve AFM1 için belirlenen tayin sınırı (LOD) değerleri sırasıyla 1.04 pg.mL-1 ve 0.4 pg.mL-1 olarak bulunmuştur. Ayrıca AFB1 ile kirletilmiş mısır ve fıstık gıda örneklerinde AFB1 tayini gerçekleştirilmiştir. Rastgele bir mandıracıdan alınan ham süt örneklerinde ise AFM1 tayini gerçekleştirilmiştir. Aflatoksin baskılanmış sensörlerin tekrarlanabilirliği ve raf ömrü kararlılıkları incelenmiştir. Tasarlanan çiplerin polimer film yüzey homojenliğini belirlemek için Scatchard, Langmuir, Freundlich ve Langmuir-Freundlich adsorpsiyon izotermleri kullanılarak hesaplanmıştır. Hem AFB1 hemde AFM1 baskılanmış nanofilm kaplı çiplerde adsorpsiyon davranışı, Langmuir modeline uygun olarak bulunmuştur

Approximate solutions for fractional order variable coefficients differential equations and the system of such equations by hermite collocation method

Bu tezde, kesir mertebeli lineer diferensiyel denklem ve denklem sistemlerinin yaklaşık çözümleri için Hermite Collocation Metodu (HCM) geliştirilmiştir. Metot, bahsedilen diferensiyel denklem veya denklem sistemini, sıralama (collocation) noktalarını kullanarak, bilinmeyenleri Hermite katsayıları olan lineer cebirsel denklem sistemine dönüştürmektedir. Bu cebirsel sistem ise matrislerle ifade edilebilmekte ve matris cebri kullanarak sistemin kolayca çözülmesiyle de kesirli mertebeden lineer denklem ve sistemlerinin kesilmiş seri cinsinden yaklaşık çözümlerine ulaşılabilmektedir.In this thesis, the Hermite Collocation method (HCM) has been developed for the approximate solution for the fractional order linear differential equations and the system of such equations. The method, by using collocation points, converts the mentioned equations or the system of such equations to the linear algebraic systems of which unknowns are Hermite coefficients. Since expressing this algebraic systems by matrices and using matrix algebra solution of the algebraic system can be obtained easily. As a result, the solutions of the fractional order linear equations and the system of such equations are obtained in terms of truncated Hermite series

Development of Gold Nanoparticles Decorated Molecularly Imprinted–Based Plasmonic Sensor for the Detection of Aflatoxin M1 in Milk Samples

Aflatoxins are a group of extremely toxic and carcinogenic substances generated by the mold of the genus Aspergillus that contaminate agricultural products. When dairy cows ingest aflatoxin B1 (AFB1)−contaminated feeds, it is metabolized and transformed in the liver into a carcinogenic major form of aflatoxin M1 (AFM1), which is eliminated through the milk. The detection of AFM1 in milk is very important to be able to guarantee food safety and quality. In recent years, sensors have emerged as a quick, low–cost, and reliable platform for the detection of aflatoxins. Plasmonic sensors with molecularly imprinted polymers (MIPs) can be interesting alternatives for the determination of AFM1. In this work, we designed a molecularly–imprinted–based plasmonic sensor to directly detect lower amounts of AFM1 in raw milk samples. For this purpose, we prepared gold–nanoparticle–(AuNP)−integrated polymer nanofilm on a gold plasmonic sensor chip coated with allyl mercaptan. N−methacryloyl−l−phenylalanine (MAPA) was chosen as a functional monomer. The MIP nanofilm was prepared using the light–initiated polymerization of MAPA and ethylene glycol dimethacrylate in the presence of AFM1 as a template molecule. The developed method enabled the detection of AFM1 with a detection limit of 0.4 pg/mL and demonstrated good linearity (0.0003 ng/mL–20.0 ng/mL) under optimized experimental conditions. The AFM1 determination was performed in random dairy farmer milk samples. Using the analogous mycotoxins, it was also demonstrated that the plasmonic sensor platforms were specific to the detection of AFM1

Recent Advances in Quartz Crystal Microbalance Biosensors Based on the Molecular Imprinting Technique for Disease-Related Biomarkers

The molecular imprinting technique is a quickly developing field of interest regarding the synthesis of artificial recognition elements that enable the specific determination of target molecule/analyte from a matrix. Recently, these smart materials can be successfully applied to biomolecule detection in biomimetic biosensors. These biosensors contain a biorecognition element (a bioreceptor) and a transducer, like their biosensor analogs. Here, the basic difference is that molecular imprinting-based biosensors use a synthetic recognition element. Molecular imprinting polymers used as the artificial recognition elements in biosensor platforms are complementary in shape, size, specific binding sites, and functionality to their template analytes. Recent progress in biomolecular recognition has supplied extra diagnostic and treatment methods for various diseases. Cost-effective, more robust, and high-throughput assays are needed for monitoring biomarkers in clinical settings. Quartz crystal microbalance (QCM) biosensors are promising tools for the real-time and quick detection of biomolecules in the past two decades A quick, simple-to-use, and cheap biomarkers detection technology based on biosensors has been developed. This critical review presents current applications in molecular imprinting-based quartz crystal microbalance biosensors for the quantification of biomarkers for disease monitoring and diagnostic results

Quartz Crystal Microbalance-Based Aptasensors for Medical Diagnosis

Aptamers are important materials for the specific determination of different disease-related biomarkers. Several methods have been enhanced to transform selected target molecule-specific aptamer bindings into measurable signals. A number of specific aptamer-based biosensors have been designed for potential applications in clinical diagnostics. Various methods in combination with a wide variety of nano-scale materials have been employed to develop aptamer-based biosensors to further increase sensitivity and detection limit for related target molecules. In this critical review, we highlight the advantages of aptamers as biorecognition elements in biosensors for target biomolecules. In recent years, it has been demonstrated that electrode material plays an important role in obtaining quick, label-free, simple, stable, and sensitive detection in biological analysis using piezoelectric devices. For this reason, we review the recent progress in growth of aptamer-based QCM biosensors for medical diagnoses, including virus, bacteria, cell, protein, and disease biomarker detection

Microfluidic Systems for Cancer Diagnosis and Applications

Microfluidic devices have led to novel biological advances through the improvement of micro systems that can mimic and measure. Microsystems easily handle sub-microliter volumes, obviously with guidance presumably through laminated fluid flows. Microfluidic systems have production methods that do not need expert engineering, away from a centralized laboratory, and can implement basic and point of care analysis, and this has attracted attention to their widespread dissemination and adaptation to specific biological issues. The general use of microfluidic tools in clinical settings can be seen in pregnancy tests and diabetic control, but recently microfluidic platforms have become a key novel technology for cancer diagnostics. Cancer is a heterogeneous group of diseases that needs a multimodal paradigm to diagnose, manage, and treat. Using advanced technologies can enable this, providing better diagnosis and treatment for cancer patients. Microfluidic tools have evolved as a promising tool in the field of cancer such as detection of a single cancer cell, liquid biopsy, drug screening modeling angiogenesis, and metastasis detection. This review summarizes the need for the low-abundant blood and serum cancer diagnosis with microfluidic tools and the progress that has been followed to develop integrated microfluidic platforms for this application in the last few years

Preparation of Surface Plasmon Resonance Aptasensor for Human Activated Protein C Sensing

Nucleic acid aptamers are an emerging class of artificial ligands and have recently gained attention in several areas. Here we report the design of a surface plasmon resonance (SPR) aptasensor for highly sensitive and selective sensing of human activated protein C (APC). First, DNA aptamer (DNA-Apt) specific for APC is complexed with N-methacryloyl-L-cysteine (MAC) monomer. Then, 2-hydroxyethyl methacrylate (HEMA) and cyanamide are mixed with the DNA-Apt/MAC complex. The SPR aptasensor is characterized by atomic force microscopy, ellipsometry, and contact angle measurements. Selectivity of SPR aptasensor is carried out in the presence of myoglobin (Myb), hemoglobin (Hb), and bovine serum albumin (BSA). Limit of detection (LOD) and limit of quantification (LOQ) values are 1.5 ng mL?1 and 5.2 ng mL?1, respectively. DNA-Apt SPR aptasensor performance for APC detection is also examined in artificial plasma. © 2022, Springer Science+Business Media, LLC, part of Springer Nature