Chemistry / Kimya

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  • Article
    Citation - Scopus: 3
    Development of Chrono-Spectral Gold Nanoparticle Growth Based Plasmonic Biosensor Platform
    (Elsevier, 2024) Sözmen, Alper Baran; Elveren, Beste; Erdoğan, Duygu; Mezgil, Bahadır; Baştanlar, Yalın; Yıldız, Ümit Hakan; Arslan Yıldız, Ahu
    Plasmonic sensor platforms are designed for rapid, label-free, and real-time detection and they excel as the next generation biosensors. However, current methods such as Surface Plasmon Resonance require expertise and well-equipped laboratory facilities. Simpler methods such as Localized Surface Plasmon Resonance (LSPR) overcome those limitations, though they lack sensitivity. Hence, sensitivity enhancement plays a crucial role in the future of plasmonic sensor platforms. Herein, a refractive index (RI) sensitivity enhancement methodology is reported utilizing growth of gold nanoparticles (GNPs) on solid support and it is backed up with artificial neural network (ANN) analysis. Sensor platform fabrication was initiated with GNP immobilization onto solid support; immobilized GNPs were then used as seeds for chrono-spectral growth, which was carried out using NH2OH at varied incubation times. The response to RI change of the platform was investigated with varied concentrations of sucrose and ethanol. The detection of bacteria E.coli BL21 was carried out for validation as a model microorganism and results showed that detection was possible at 102 CFU/ml. The data acquired by spectrophotometric measurements were analyzed by ANN and bacteria classification with percentage error rates near 0% was achieved. The proposed LSPR-based, label-free sensor application proved that the developed methodology promises utile sensitivity enhancement potential for similar sensor platforms. © 2024 The Author(s)
  • Book Part
    Citation - Scopus: 3
    Tissue Engineering Applications of Marine-Based Materials
    (Springer, 2022) Polat, Hürriyet; Zeybek, Nuket; Polat, Mehmet
    Tissue engineering is a promising approach in replacing or improving tissues lost or has become nonviable due to disease or trauma by the use of scaffold materials by combining engineering and biochemical/physicochemical methods. Its purpose is to create suitable matrices that support cell differentiation and proliferation toward the formation of new and functional tissue. Marine-based natural compounds are potential scaffold feedstock material in tissue engineering owing to their biocompatibility and biodegradability while providing excellent biochemical/physicochemical properties. Numerous application areas and various fabrication routes techniques described in the literature attest to the importance of these materials in tissue regeneration. This review has been carried to merge the information from a large number of studies on the marine-based scaffold materials in tissue engineering into a coherent summary. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2022.
  • Conference Object
    Citation - WoS: 1
    Citation - Scopus: 1
    Biomimetic Peptide-Conjugated Membranes for Developing an Artificial Cornea
    (IEEE, 2022) Sunal, Gülşah; Pulat, Günnur; Akgün, İsmail Hakkı; Güven, Sinan; Yıldız, Ümit Hakan; Karaman, Ozan; Horzum, Nesrin
    The corneal endothelium is composed of a single layer of specialized endothelial cells, protecting, and nourishing the inner surface of the cornea. Corneal endothelial cells do not proliferate after birth and their number decrease with age. Trauma, inflammation, or surgical intervention can cause cell loss. When damage is extensive and the density of corneal endothelial cells decreases to a critical level, it results in corneal edema and vision loss. Besides them, when corneal endothelium has irreversible damage, the only treatment way is corneal transplantation. But there are some drawbacks such as finding donors, immune reactions, and the number of patients waiting on the transplantation lists for years. Tissue engineering approaches can provide promising alternatives for the regeneration of corneal endothelium tissue. Peptides can be used to modify and functionalize the scaffolds, allowing for the production of bioactive and biomimetic surfaces. Peptide-modified scaffold surfaces might direct and enhance the behaviors of cells. In this study, the aim was to functionalize the polycaprolactone (PCL) membranes with tissue-specific peptides and to characterize the peptide-conjugated membranes by Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and X-ray Photoelectron Spectroscopy (XPS) analysis. The synthesized peptides were successfully conjugated on the PCL biomembranes.
  • Article
    Determination of Triacylglycerol Composition of Ayvalık and Memecik Olive Oils During Storage by Chemometric Methods
    (Sakarya Üniversitesi, 2017) Köseoğlu, Oya; Sevim, Didar; Özdemir, Durmuş
    The aim of present investigation is to discriminate two important Turkish olive cultivars (Ayvalık and Memecik) by studying their triacylglycerol (TAG) compositions during storage (15 months) taken from different orchard in Ayvalık and Aydın region which have a significant potential for olive oil production in Turkey, during 2009 and 2010 harvest years. Olives were harvested by hand at 2 different maturation indices and processed by an Abencor system. The olive oil samples were stored at room temperature and they were divided into two groups including exposed to diffused daylight and dark for a period of 15 months. Multivariate classification and clustering were done by the application of unsupervised chemometrics methods such as principal component analysis (PCA) and hierarchical cluster analysis (HCA) based on the TAG profiles of the olive oil samples. PCA and HCA analysis of olive oils showed significant differences according to harvest years and cultivars. PCA scores plot showed that the samples were classified into two main groups with respect to harvest years based on the first principal component (PC1). In terms of storage effect, there was no significant change in TAG compositions among the samples from beginning of storage to 15 months of storage regardless of storage conditions (either in dark or in daylight). In addition, PCA scores plot indicated that the samples were also successfully clustered into two sub-groups according to cultivars in both years based on the second principal component (PC2).
  • Article
    Extraction and Characterization of Pectin From Fresh Globe Artichoke and Canned Artichoke Waste
    (Gıda Teknolojisi Derneği, 2017) Ceylan, Çağatay; Bayraktar, Oğuz; Atçı, Erhan; Sarrafi, Şahin
    The pectin contents of fresh globe artichoke (stem, receptacle, and bract) and waste of artichokecanning industry were investigated. The highest pectin amount was found in the stem part of freshglobe artichoke (6.42%) with the highest amount of anhydrogalacturonic acid (AGA) and anhydrouronicacid (AUA) content. The pectin yields of receptacle and bract parts were found to be 5.31 and 4.55%,respectively. The pectin yield from the industrial waste was the lowest, 4.43%. The highest ash content(5.65 %) along with the lowest anhydrouronic acid amount (73.28%) indicated the lowest purity for theindustrial waste. The degrees of esterification for the pectin obtained from the stem, receptacle andbract parts were 55.26%, 52.26%, and 56.17%, respectively indicating the presence of high methyl-esterified(HM) pectin. The pectin from the industrial waste had the lowest degree of esterification (46.02%). TheFTIR results indicated that acid processing affected the structural properties of pectin from the industrialwaste with higher methoxyl content and esterification degree.
  • Article
    Nonlinear Inorganic Optical Materials
    (Ege Üniversitesi, 1999) Topaloğlu, Işıl
    Ticari olarak uygulamaları bulunan nonlinear optik materyallerin geliştirilmesi için yapılmakta olan çalışmalar özellikle 1980 yılından sonra artış göstermiştir. Bu amaçla incelenen sistemler arasında inorganik kristaller, yarı iletkenler, organometalik bileşikler, organik kristalin monomerler, ve delokalize $\Pi$ elektronları içeren uzun zincirli polymerler Informasyon işlemlerinde optik çevirme, telekominikasyon, optoteknoloji, ve optik frekans çevirme amaçlı olarak çok yaygın olarak kullanılmaktadır. Bu derleme makalesinde nonlinear optik özellik gösteren inorganik bileşikler hakkında kısa bilgi verilmiştir.
  • Article
    Determination of Bitterness Index (k225) and Total Fenol Content of Olive Oils Obtained With Different Regions, Varieties and Processing Systems
    (Ege Üniversitesi, 2018) Köseoğlu, Oya; Sevim, Didar; Dural, Mehmet Ulaş; Özdemir, Durmuş
    In this work the effect of different growing areas on olive (Ayvalık, Memecik, Gemlik, Beylik, Edincik Su, Girit, Kilis Yağlık, Sarı Ulak, Tavşan Yüreği, Topak Aşı) oil bitterness index (K225) were studied at the South Marmara, South and North Aegean, West and East Mediterranean  Regions at two, two and a half (2.5), and three phase extraction system, during 2014/2015 crop season. A total of 41 virgin olive oils samples were collected from these Regions. Total phenol content and bitternes index (K225) were analyzed in the research. A Solid-Phase Extraction procedure were carried out for extraction of the bitter compounds. The results of total phenol content and K225 values showed that the Beylik olive oil was determined with the highest total phenol conent and bitterness index (K225) with 330.26 mg CAE kg-1 oil  and 1.21 at 2.5 phase extraction system from Manavgat at the West Mediterranean Region, respectively. After the Beylik  variety, the highest total phenol content was determined Ayvalık and Edincik Su olive oil with 291.03 and 270.62 mg CAE kg-1 oil, respectively. The Memecik and Ayvalık olive oil bitterness index (K225) was determined 0.86 and 0.85 at two phase extraction system from Muğla and Burhaniye at the South and North Aegean, respectively. 
  • Conference Object
    Effect of Some Physical, and Chemical Variables on Flocculation and Sediment Behaviour
    (A.A. Balkema Publishers, 2000) Polat, Hürriyet; Polat, Mehmet; İpekoğlu, Üner
    Effect of some chemical and physical variables on the settling rate, final sediment height, sediment viscosity and supernatant turbidity of a clay sample was studied using various polyacrylamide type flocculants. Increasing flocculant concentration significantly increased both the settling rate and sediment viscosity. More importantly, changes in the final sediment, height, hence the packing density, was minimal for all the conditions tested once the sediment was allowed to consolidate. Also, the mode of addition of the polymer, at once or continuous, did not seem to affect any of the parameters measured. Conditioning time seemed to alter the settling rate at low polymer concentrations, but had no effect at high polymer concentrations. However, increasing the conditioning time caused a decrease in the sediment viscosity. Different types of the polyacrylimides generated different settling rates at a given concentration, but the final sediment height was nearly independent of polymer type.
  • Conference Object
    Use of Ion Flotation To Remove Copper From Waste Waters
    (2006) Erdoğan, Demet; Polat, Hürriyet; İpekoğlu, Üner
    Flotation studies were carried out to investigate the removal of copper from wastewaters. Various parameters such as pH, surfactant and frother concentrations and airflow rate were tested to determine the optimum flotation conditions. Sodium dodecyl sulfate and Hexadecyltrimethyl ammonium bromide were used as collectors. Recoveries as high as 90% could be to obtained under optimum conditions.
  • Book Part
    Citation - Scopus: 6
    Recent Advances in Chitosan-Based Systems for Delivery of Anticancer Drugs
    (Springer, 2020) Polat, Mehmet; Polat, Hürriyet
    Problems in transporting drug molecules to tumor sites in required dose or constitution lead to low efficacy and significant side effects. Shielding the drug molecules in micelles, liposomes, or nanoparticles is a major line of investigation to improve chemotherapeutic treatment. Though compatibility for proper envelopment of the drug and timely release at the tumor site are required of such a carrier, protecting its own physicochemical and morphological integrity during transport is another precondition. Because of its superior polymerization capability, biocompatibility, pH dependence, and charging characteristics, chitosan has been in the forefront of potential drug carriers. Numerous synthesis routes for chitosan-based nanocarriers have been suggested to the extent that a search of the literature published since 2000 with the keywords “novel + nano + chitosan” in the title results in 527 articles, indicating the bewildering quality and quantity of the new information. This review was carried out not only to peruse this large amount of work on chitosan-based anticancer drug delivery but also to extract manageable patterns from numerous synthesis routes. The main conclusion is that the synthesis methods suggested in literature can be combined into two main routes, and the degree of hydrophobicity of the drug determines which route should be followed. © Springer Nature Singapore Pte Ltd. 2019.