Gallik asit tayini için elektrokimyasal sensör olarak yarıiletken nanokompozit yapılarının geliştirilmesi
Development of semiconductor nanocomposite structures as electrochemical sensors for the determination of gallic acid
- Tez No: 898391
- Danışmanlar: PROF. DR. MAHMUT ÖZACAR
- Tez Türü: Yüksek Lisans
- Konular: Kimya, Chemistry
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2024
- Dil: Türkçe
- Üniversite: Sakarya Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Kimya Ana Bilim Dalı
- Bilim Dalı: Fizikokimya Bilim Dalı
- Sayfa Sayısı: 113
Özet
Antioksidanlar, insan vücudundaki serbest radikalleri temizleyerek birçok doğal hastalığı iyileştirir. Bu nedenle, antioksidan içeren gıdaların tüketimi artmıştır. Ancak, yapay antioksidanların aşırı alımı kanser gibi hastalıklara neden olabilir. Bu yüzden, doğal kaynaklardan elde edilen antioksidanlar tercih edilmektedir. Gallik asit (GA), doğal örneklerde bulunan bir antioksidandır. Bazen 3,4,5- trihidroksibenzoik asit olarak da bilinen gallik asit, bir polifenol grubu üyesidir. C₆H₂(OH)₃CO₂H moleküllerinden oluşur. Gallik asit, sarı-beyaz renkte olup kristal bir yapıya sahiptir. Suda kolayca çözünür ve eter, alkol, gliserol gibi maddelerde de çözünebilir, ancak benzen ve kloroformda çözünmez. Nar, muz, böğürtlen, yaban mersini, avokado, frenk üzümü, mango, dut ve sumak gibi birçok meyvede; ayrıca yeşil çay, sumak, fındık, meşe ve kestane ağaçları gibi bitkisel ürünlerde ve bazı ağaç kabuklarında gallik asit bulunur. Bu çalışmada, gallik asit (GA) tayini için çinko oksit (ZnO), çinko sülfür (ZnS) ve çinko selenid (ZnSe) yarı iletkenleri kullanılarak elektrokimyasal sensörler geliştirildi ve elektrot üretimi için camsı karbon elektrot (GCE) kullanıldı. GA tayini, 0.1 M fosfat tamponu (PBS) (pH 7.4) içeren çözeltilerde farklı GA konsantrasyonlarında hazırlanan GCE/ZnS, GCE/ZnSe, GCE/ZnO çalışma elektrotları kullanılarak yapıldı. Oluşturulan GA sensörleri, 10 µM ile 1000 µM arasında geniş bir doğrusal yanıt aralığı gösterdi. GCE/ZnS, GCE/ZnSe, GCE/ZnO elektrotlarıyla geliştirilen elektrokimyasal sensörler, GA tayini için yüksek hassasiyet, iyi tekrarlanabilirlik, yüksek seçicilik ve uzun vadeli stabilite gösterdi. Geliştirilen GA sensörü, GCE/ZnS, GCE/ZnSe, GCE/ZnO elektrotlarında farklı LOD ve LOQ değerleri gösterdi ve -0.80 V, 1.00 V'da 10-100 µM GA konsantrasyon aralığında doğrusal bir yanıt verdi. LOD-LOQ değerleri sırasıyla 9.03 µM-27.36 µM, 6.33 µM-19.203 µM, 5.55 µM-16.84 µM olarak gözlemlendi. Elektrokimyasal sensöre ek olarak, Folin-Ciocalteu yöntemiyle spektrofotometrik olarak da GA tayini yapıldı ve sonuçlar karşılaştırıldı. Folin-Ciocalteu yöntemiyle elde edilen sensörün LOD değeri 5.48 µM ve LOQ değeri 16.62 µM olarak bulundu. Ayrıca, gerçek kiraz suyu ve ceviz örneklerinde GA tayini yapıldı ve geri kazanım değerleri %98.15-101.84 aralığında belirlendi. GA, Folin-Ciocalteu yöntemi ve elektrokimyasal sensör kullanılarak spektrofotometrik olarak belirlendi ve sonuçlar karşılaştırıldı. GA ayrıca vişne suyu ve ceviz gibi gerçek örneklerde de belirlendi.
Özet (Çeviri)
Free radicals are molecules or atoms with one or more unpaired electrons outside their orbitals. These unpaired electrons are denoted by a dot adjacent to the atom or molecule. Free radicals, in their quest to complete their missing electrons, exhibit high reactivity and a strong tendency to form bonds and compounds. Bond formation necessitates the presence of two electrons with spins oriented in opposite directions. Electron pairs involved in bond formation exhibit structurally stable configurations. Electrons within the human body form compounds and pairs due to the bonds they establish. Upon bond disruption, electrons either disperse to other atoms or remain on a single atom. When electrons remain localized on a single atom, ions are formed, whereas their dispersion to different atoms results in the formation of free radicals. Unpaired electrons possess unexpectedly high energy levels, which can lead to the disruption of paired electrons in other molecules. Antioxidants are substances that inhibit or decelerate undesirable oxidation reactions. They neutralize free radicals, thereby preventing cellular damage induced by oxidative stress. Consequently, due to their role in naturally ameliorating various medical conditions caused by free radicals within the human body, there has been an observed increase in the consumption of antioxidant-rich foods. However, excessive intake of artificially synthesized antioxidants may lead to adverse health conditions, such as cancer. Therefore, antioxidants derived from natural sources are favored. Phenolic compounds are one of the secondary metabolites synthesized during the normal development of plants. These phenolic substances typically possess one or more hydroxyl groups attached to an aromatic ring and can be categorized as metabolic products with varied structures and functions. Phenolic compounds present in foodstuffs are predominantly found in fruits; however, their presence can vary depending on the type of fruit. Even within the same fruit species, the concentration of phenolic compounds can be influenced by multiple factors, including species, growth season, environmental conditions, climatic factors, soil type, geographical location, and ripeness. The term 'oxidative stability' in foods can be modified by phenolics, which can alter attributes such as bitterness, color, taste, pungency, flavor, and aroma. The presence of these compounds significantly impacts the sensory characteristics and shelf life of foods, thereby enhancing consumer acceptance and nutritional value. The hydroxylation pattern around the aromatic ring dictates antioxidant activity. The capacity to act as a hydrogen donor and inhibit oxidation is directly proportional to the number of hydroxyl groups present on the phenolic rings. The fundamental attribute of a molecule or antioxidant system is its ability to maintain equilibrium and, consequently, contribute to the reduction of oxidative stress-induced damage in human metabolism by disrupting or recognizing oxidative propagation chains. Phenolic compounds found in foods, particularly in fruits, have notable health benefits despite lacking direct nutritional functions. Flavonoids and other plant polyphenols are significant antioxidants due to their high redox potentials. Grape seed extract, recognized for its potent antioxidant properties, neutralizes free radicals while exhibiting cytotoxic effects against cancerous cells without harming healthy cells. It has been reported to prevent prostate cancer, and gallic acid (GA) has demonstrated significant effects against leukemia. Additionally, GA possesses protective properties against chronic cardiovascular diseases and cancer. Phenolic compounds in foods, despite lacking nutritional functions, have positive health benefits. Due to their high redox potentials, flavonoids and other plant polyphenols serve as very important antioxidants. The antioxidant effects of phenolic compounds are explained by their ability to bind with metals, form chelates, and inactivate spesifik enzymes. The most common group of naturally occurring phenolic substances is flavonoids. Other phenolic compounds include simple phenols, phenolic acids (such as benzoic and cinnamic acids), coumarins, stilbenes, hydrolyzable and condensed tannins, lignans, and lignins. These diverse phenolic compounds are found across a wide range of plants and thus plant-based foods, providing numerous beneficial effects on human health. Gallic acid (GA), a notable antioxidant present in natural samples, is a member of the polyphenol group and is sometimes referred to as 3,4,5-trihydroxybenzoic acid. Comprising C6H2(OH)3CO2H molecules, gallic acid is a yellow-white crystalline substance. It is highly soluble in water and dissolves in ether, alcohol, and glycerol, but is insoluble in benzene and chloroform. Gallic acid can be found in various fruits such as pomegranate, banana, blackberry, blueberry, avocado, currant, mango, mulberry, and sumac, as well as in plant products like green tea, sumac, walnut, oak, chestnut trees, and certain barks. In recent years, various chromatographic techniques and methods such as chemiluminescence spectrophotometry have been employed for the detection of phenolic compounds. The electrochemical detection of gallic acid occurs due to the release of electrons during its oxidation. Gallic acid is utilized as a standard compound for determining the phenolic content in diverse biological food, juice, and plant samples. In this study, electrochemical sensors for the detection of gallic acid were developed using glassy carbon electrodes (GCE) in conjunction with semiconductors such as zinc oxide (ZnO), zinc sulfide (ZnS), and zinc selenide (ZnSe). Gallic acid detection was performed using these electrochemical sensors with GCE/ZnS, GCE/ZnSe, and GCE/ZnO working electrodes in solutions containing various concentrations of GA in 0.1 M phosphate buffer (PBS) (pH 7.4). The developed GA sensors exhibited a broad linear response range from 10 μM to 1000 μM. The electrochemical sensors developed with GCE/ZnS, GCE/ZnSe, and GCE/ZnO electrodes demonstrated high sensitivity, excellent reproducibility, high selectivity, and long-term stability for GA detection.
Benzer Tezler
- Fenolik madde tayini için plazma polimerizasyonu yöntemi ile elektrokimyasal sensör hazırlanması
Preparation of electrochemical sensor by plazma polymerization technique for phenolic compounds
BEYHAN GÜNAYDIN
Yüksek Lisans
Türkçe
2009
Gıda MühendisliğiHacettepe ÜniversitesiGıda Mühendisliği Ana Bilim Dalı
PROF. DR. MEHMET MUTLU
- Polifenol türevli antioksidanlar için sensör geliştirilmesi ve analitik uygulamaları
Sensor development and analytic applications for polyfenol derivative antioxidants
NURCAN AYHAN
Yüksek Lisans
Türkçe
2018
Kimyaİnönü ÜniversitesiKimya Ana Bilim Dalı
DR. ÖĞR. ÜYESİ SERAP TİTRETİR
PROF. SÜLEYMAN KÖYTEPE
- Biyomoleküllerde oksidatif hasarı engelleyici antioksidan aktivite tayini için elektrokimyasal yöntem geliştirilmesi
Electrochemical method development for determining antioxidant activity preventing oxidative hazard in biomolecules
AYŞE NUR ÖNEM
Doktora
Türkçe
2022
Kimyaİstanbul Üniversitesi-CerrahpaşaKimya Ana Bilim Dalı
PROF. DR. MUSTAFA REŞAT APAK
PROF. DR. KEVSER SÖZGEN BAŞKAN
- Reaktif oksijen türleri süpürücü antioksidan aktivitenin ölçümünde modifiye CUPRAC yöntemlerinin geliştirilmesi
Development of modified CUPRAC methods for reactive oxygen species scavenging antioxidant activity measurement
MUSTAFA ÖZYÜREK
- Sülfanilik asit kullanılarak gallik asit ve kuersetinin eşzamanlı spektrofotometrik tayini için metod geliştirme
Başlık çevirisi yok
DERYA CEMEK SARI