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.
  • 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.
  • Conference Object
    Citation - WoS: 2
    Citation - Scopus: 1
    Determination of Aluminum Oxide Thickness on the Annealed Surface of 8000 Series Aluminum Foil by Fourier Transform Infrared Spectroscopy
    (Springer, 2017) İnanç Uçar, Özlem; Ekin Meşe, Ayten; Birbaşar, Onur; Dündar, Murat; Özdemir, Durmuş
    Aluminum foil produced with prescribed thermomechanical processing route develop oxide film. Alloy chemistry and annealing practices, particularly its duration and exposed temperature, determine the characteristics of the oxide film. The magnitude and characteristics of the oxide film may impair surface features leading to serious problems in some applications, such as coating, printing and in some severe cases failure in formability. Therefore, it is important for the rolling industry to be able to monitor the oxide formation on the foil products and quantify its thickness. Well known methods to measure an oxide thickness that is in the order of nanometer, require meticulous sample preparation techniques, long duration for measurements and sophisticated equipment. However, in this study, a simple and rapid grazing angle attenuated total reflectance infrared (GA-ATR-FTIR) spectroscopic method combined with chemometrics multivariate calibration has been developed for the oxide thickness determination which is validated with x-ray photoelectron spectroscopy (XPS). 3000 and 8000 series aluminum foil materials which were produced by twin roll casting technique were used in this study. Foil samples were annealed at various different temperatures and annealing times in a laboratory scale furnace. Immediately after collecting GA-ATR-FTIR spectra, the 3000 series alloy samples were sent to a laboratory where XPS reference oxide thickness measurements had been performed. Partial Least Squares (PLS) method was used to develop a multivariate calibration model based on FTIR spectra and XPS reference oxide thickness values in order to predict the aluminum oxide thickness. The correlation coefficient of XPS reference oxide thickness values versus grazing angle ATR-FTIR based PLS predicted values was found as 0.9903 the standard error of cross validation (SECV) was found to be 0.29 nm in range of 4.9–14.0 nm for Al2O3. In addition, the standard error of prediction (SEP) for the validation set was 0.24 nm with the model generated with three principal components (PCs). © The Minerals, Metals & Materials Society 2017.
  • Book Part
    Citation - Scopus: 8
    The Multiwavelength Uv/Vis Detector: New Possibilities With an Added Spectral Dimension
    (Springer Verlag, 2016) Karabudak, Engin; Cölfen, Helmut
    The multiwavelength (MWL) detector is a new type of absorption detector for AUC. The commercial absorption detector of the Beckman Coulter XLA AUC can only handle a single wavelength per scan with the possibility to scan at maximum 3 wavelengths, whereas MWL-AUC can handle all the wavelengths in the UV/Vis region at one time. The result is impressive since now a full spectral dimension is added to each single scan. In this chapter, we are explaining development history, instrumentation, and future perspective of MWL-AUC.
  • Conference Object
    Citation - Scopus: 1
    Yapay Sindirim Sıvısında Doğal Zeolitlerde Meydana Gelen Morfolojik Değişmeler
    (Institute of Electrical and Electronics Engineers Inc., 2009) Demirbüker Kavak, Dilek; Özçelik, Serdar; Ülkü, Semra
    Doğal zeolitler biyoaktif maddelerdir. Doğal zeolitlerin hayvanlarda biyokütle arttırıcı besi katkı maddesi, insanlarda ülser tedavisinde mide asitliğini tamponlayıcı, asitliği düşürücü ilaç gibi değişik kullanım alanları mevcuttur. Değişik sağlık alanlarında kullanımlarından dolayı, zeolitlerin yapısal stabilitesinin sindirim sırasında belirlenmesi; olası olumlu veya olumsuz etkileşimleri anlamak açısından önem taşımaktadır. Gerçekleştirilen araştırmada, yapay sindirim sırasında zeolitte meydana gelebilecek olası morfolojik değişimlerin incelenmesi hedeflenmiştir. Bu amaçla zeolitin ABTS ile radikal sönümleme kapasitesi araştırılmış, yapay sindirim denemeleri gerçekleştirilerek de uygulama süreci sonrası yapıda olası değişimler ve adsorpsiyonlar taramalı elektron mikroskobu, FTIR, XRD analizleri ile incelenmiştir. 3g/100ml zeolitin ABTS radikalini %45 inhibe ettiği bulunmuştur. Taramalı elektron mikroskobu deneyleri sonucunda yapay sindirilmiş örneklerin yüzey morfolojisinde değişim gözlenmemiştir. Element analizleri yapısal kaybın olmadığını, Al ve Si elementlerinin ağırlıkça yüzdelerinin, kontrol örnekleriyle (Al:8.1; Si: 39) sindirilmiş örneklerde (Al:8.2; Si: 38.3) yaklaşık aynı olduğunu göstermiştir. Infrared spektrum (IR) ve X-ray ışını kırınımı analizleri sonuçları ise bu bulguları doğrulamıştır. Ayrıca taramalı elektron mikroskobu ve IR spektrum sonuçları yapay sindirim ortamındaki maddelerin, zeolit yüzeyinde adsorplanmadıklarıını göstermektedir. Sonuç olarak doğal zeolitler, yapay sindirim sırasında yapısal stabilitelerini kaybetmemektedirler.
  • Conference Object
    Citation - Scopus: 2
    Utilization of Near Ir Absorbing Gold Nanocolloids by Green Synthesis
    (Trans Tech Publications, 2018) Elveren, Beste; Yıldız, Ümit Hakan; Arslan Yıldız, Ahu
    The rapid developments in nanoscience, and its applications on biomedical areas have a large impact on drug delivery, tissue engineering, sensing, and diagnosis. Gold is widely investigated nanomaterial for the last couple of decades, since it has unique surface properties and very low toxicity to biological environment. In this work, we present a novel synthesis of gold nanoparticles (GNPs) exhibiting both visible and near-IR absorbance without agglomeration. The surface of GNPs were analyzed by routine methods and the binding kinetics were investigated by Surface Plasmon Resonance (SPR) Spectroscopy. The unique optical properties of near-IR asorbing GNP colloids hold promise for biological applications.
  • Conference Object
    Citation - WoS: 1
    Citation - Scopus: 4
    Polymer Nanofiber-Carbon Nanotube Network Generating Circuits
    (SPIE, 2018) Mutlu, Mustafa Umut; Akın, Osman; Yıldız, Ümit Hakan
    The polymer nanofiber carbon nanotube (CNT) based devices attracts attention since they promise high performance for next generation devices such as wearable electronics, ultra-light weighted appliances and foldable devices. This abstract describes the utilization of polymer nanofibers and CNT as major component of low cost foldable photo-resistor. We use polymer nanofiber as template guiding CNTs to generate nanocircuits and conductive sensing network. The controlled combination of CNTs and polymer nanofibers provide opportunities for device miniaturization without loss of performance. The nanofiber-CNT network based photo-resistor exhibits broad band response 400 to 1600 nm that holding promises for ultra-thin devices and new sensing platforms.