Kimya - Metalurji Fakültesi

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http://hdl.handle.net/11527/17537

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  • Öge
    A study on tailoring silver release from micro-arc oxidation coating fabricated on titanium
    (Wiley, 2024) Kayan, Gizem Özge ; Muhaffel, Faiz ; Kayan, Asgar ; Nofar, Mohammadreza ; Cimenoglu, Huseyin ; orcid.org/0000-0002-4364-2930 ; orcid.org/0000-0002-9921-7108 ; Metalurji ve Malzeme Mühendisliği
    This study is initiated with the aim of regulating the release of silver (Ag) as an antibacterial agent from the micro-arc oxidation (MAO) coating. Herein, an external 5 wt% Tin(II) chloride (SnCl2) containing biodegradable polycaprolactone (PCL) layer is formed on the 0.8 wt% Ag-incorporated MAO coating by the dip coating method. 5 wt% SnCl2 addition into PCL provides a steady release of Ag into concentrated simulated body fluid (1.5X SBF) from the underlying MAO coating at 37 °C. When the Ag release rate is taken into consideration, it is quantified as 0.0089 and 0.0586 ppm day−1 for PCL-covered MAO and PCL-free MAO coatings, respectively. It is finally concluded that the preliminary result of this study can be promising for minimizing the in vivo adverse effects of Ag+ ions arising from rapid release as well as maintaining antibacterial efficacy for prolonged periods, which is ideal for preventing the risk of postimplantation infections.
  • Öge
    Abstract book of the international symposium on food rheology and texture, 19 October 2018 - İstanbul, Turkey
    (Istanbul Technical University Press, 2018) Kimya - Metalurji ; Lokumcu Altay, Filiz ; Toker, Ömer Said ; Dede, Sercan
  • Öge
    Alternative plant-based gluten-free sourdough pastry snack production by using beetroot and legumes: characterization of physical and sensorial attributes
    (American Chemical Society, 2024) Yolcu, Zeynep ; Demircan, Evren ; Mertdinç, Zehra ; Aydar, Elif Feyza ; Özçelik, Beraat ; 0000-0002-1810-8154 ; Gıda Mühendisliği
    Objective of this study was to design a formula of a sourdough pastry snack by adding starter inoculum into the formulation which was obtained by the fermentation process through beetroot (Beta vulgaris) puree with black-eyed pea (Vigna unguiculata) and fava bean (Vicia faba). With this development process, it was aimed to review the functional impact of legumes as gluten replacement and emphasize the importance regarding physical and sensory attributes in a pastry snack product. First, a starter inoculum was developed based on modification of the shalgam fermentation process with legumes. An experimental design suggested by the response surface methodology was used to optimize its microbial properties and level of antioxidants with the factors of amounts of beetroot puree, fava bean/black-eyed pea ratio, and fermentation time. In the second part, this starter inoculum was mixed with fava bean flour to obtain a sourdough pastry snack (FBS) with improved physical and sensory attributes and compared to the wheat control sourdough (WCS) pastry snack after the baking process. According to the optimization results to produce starter inoculum with the optimum results of lactic acid bacteria 9.55 log cfu/mL, the level of antioxidant activity 91.86 μM TE/mL, and total yeast level 6.96 log cfu/mL; 75 mL of beetroot puree, 100% for fava bean, and fermentation for 24 h were obtained. Compared to WCS, FBS has approximately 16% higher hardness values. Also, a significant difference was observed for stiffness and springiness among samples. The retention of moisture was higher in the first 4 days following the storage for 8 days; the moisture content continuously decreased with the final moisture content of 12.6%. When compared with the results of textural profile analysis in terms of hardness, stiffness, and springiness, sensory results were correlated. Comparing the overall acceptability of the FBS to WCS, FBS was from moderate to higher scores, which indicated that it could be a promising alternative to chemically developed snack products and a preferred product for people suffering from celiac disease and other gluten intolerances.
  • Öge
    Antifungal Activities of Different Essential Oils and Their Electrospun Nanofibers against Aspergillus and Penicillium Species Isolated from Bread
    (American Chemical Society, 2022) Karbancıoğlu Güler, Funda ; Devecioğlu, Tuğba ; Türker, Mustafa ; 0000-0001-6576-0084 ; 0000-0001-6681-0944 ; Food Engineering
    Mold growth, especially Aspergillus spp. and Penicillium spp., deteriorates the quality of bakery products. Essential oils (EOs) have been categorized as good natural antimicrobials. Hereby, this study aimed to evaluate the antifungal activity of six EOs, ginger, cumin, cinnamon, black pepper, origanum, and clove, and their volatile compounds against fungal strains isolated from bread: Penicillium carneum DDS4, Aspergillus flavus DDS6, and Aspergillus niger DDS7 by disc diffusion and disc volatilization methods, respectively. Among EOs, cumin, cinnamon, origanum, and clove were found to be effective against fungal strains, and their minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were determined. The observed lowest MIC value of EOs was obtained at 1000 μg/mL concentration, and the lowest MFC value was obtained from the results of clove at a concentration of 1000 μg/mL. Based on the MIC and MFC values, clove and cinnamon EOs were found to be more effective at lower concentrations. Electrospun nanofiber films of clove and cinnamon were produced with 6% poly(vinyl alcohol) (PVA), 2% β-cyclodextrin (β-CD), and 2% EO to overcome the unfavorable sensory impact of EOs on food products. The inhibitory activity of cinnamon EO film (2.64–2.51 log(CFU/mg)) was considerably lower than clove EO film (3.18–3.24 log(CFU/mg)) against P. carneum DDS4 and A. niger DDS7. Furthermore, these nanofiber films prevented fungal growth on bread samples visibly and were shown to be an alternative application for active food packaging.
  • Öge
    Cold plasma application to fresh green leafy vegetables: impact on microbiology and product quality
    (Wiley, 2023) Özdemir, Emel ; Başaran, Pervin ; Kartal, Sehban ; Akan, Tamer ; orcid.org/0000-0002-1627-7333 ; orcid.org/0000-0002-9969-6196 ; orcid.org/0000-0002-0491-4219 ; orcid.org/0000-0003-0907-2724 ; Gıda Mühendisliği
    Fresh green leafy vegetables (FGLVs) are consumed either garden-fresh or by going through very few simple processing steps. For this reason, foodborne diseases that come with the consumption of fresh products in many countries have prioritized the development of new and reliable technologies to reduce food-related epidemics. Cold plasma (CP) is considered one of the sustainable and green processing approaches that inactivate target microorganisms without causing a significant temperature increase during processing. This review presents an overview of recent developments regarding the commercialization potential of CP-treated FGLVs, focusing on specific areas such as microbial inactivation and the influence of CP on product quality. The effect of CP differs according to the power of the plasma, frequency, gas flow rate, application time, ionizing gases composition, the distance between the electrodes and pressure, as well as the characteristics of the product. As well as microbial decontamination, CP offers significant potential for increasing the shelf life of perishable and short-shelf-life products. In addition, organizations actively involved in CP research and development and patent applications (2016–2022) have also been analyzed.
  • Öge
    Combined effects of zein nanofiber coating containing laurel (laurus nobilis) and air fryer cooking on quality properties of fish fillets during cold storage
    (American Chemical Society, 2024) Ceylan, Zafer ; Meral, Raciye ; Alav, Aslıhan ; Torusdağ, Gülşen Berat ; Bildik, Fatih ; Altay, Filiz ; 0000-0002-5484-866X ; Gıda Mühendisliği
    In this study, the effects of zein nanofibers (Zn) containing ground laurel leaves (GLL) and air fry cooking on the quality characteristics of Rainbow trout (Oncorhynchus mykiss) were investigated. The zein nanofibers possessing 335.8 ± 43.6 nm average diameters were fabricated containing GLL. The Fourier transform infrared spectroscopy (FTIR) results of the zein, Zn, GLL, and zein nanofibers containing GLL (LZn) confirmed the electrospinning encapsulation of GLL into Zn and their interactions. The effects of the combination of LZn coating and air fryer cooking of fish fillets on the quality characteristics during storage at 4 °C for 10 days were monitored in terms of oxidative and microbiological stability, color, and sensory parameters. As compared to the control, the combination of LZn coating and air fryer cooking provided a microbial limitation of up to 45.21% during the analysis (p < 0.05). The changes in ΔE values between the control and the LZn-coated samples were obtained as ≤7.56 during 6 days, but then a dramatic color difference was observed. Besides overall sensory acceptability, particularly the odor parameter in the cooked fish samples coated with LZn was significantly preferred (p < 0.05). The combination of LZn coating and air fryer cooking delayed the thiobarbituric acid increase in the fish meat samples (3.51 to 2.57 mg malondialdehyde (MDA)/kg) up to the third day of storage. This study showed that LZn coating is a very functional layer on the fish meat and could be applied for not only fresh fish meat but also other fresh meat products.
  • Öge
    Cryo-assisted nitrogen treatment for the fabrication of nanoengineered, mixed transition metal oxide anode from inorganic domestic waste, for lithium-ion batteries
    (Springer, 2024) Ashraf, Humza ; Karahan, B. Deniz ; 0000-0002-7839-2222 ; Metalurji ve Malzeme Mühendisliği
    A novel method for the fabrication of nanoengineered, mixed transition metal oxide anode active material is proposed based on implementing liquid nitrogen treatment during the chemical precipitation process, for the first time in open literature. Such interference in the precipitation is believed to change the surface energy of the nuclei leading to differentiation in the growth process. To exemplify this hypothesis with an environmentally friendly approach, kitchen scourer pads, an existing waste, are used as a starting material instead of using a mixture of primary quality metals’ salts. Therefore, in this study, firstly, an optimization is realized to leach the scouring pad with 100% efficiency. Then, by applying a conventional chemical precipitation to this leachate at pH 5.5, Sample 1-P is produced. Herein, innovatively liquid nitrogen treatment is carried out during the chemical precipitation to produce Sample 2-P. Lastly, these precipitates (Samples 1-P, 2-P) are calcinated in the air to form mixed transition metal oxide powders: Samples 1 and 2, respectively. Structural, chemical, and morphological characterizations are carried out to examine the effect of liquid nitrogen treatment on the powders’ properties. To discuss the effect of nitrogen treatment on the electrochemical performances of the anode active materials (Sample 1 and Sample 2), galvanostatic tests are realized. The results show that Sample 2 demonstrates a higher 1st discharge capacity (1352 mAh/g) and retains 62% of its performance after 200 cycles when 50 mA/g current load is applied. Moreover, this electrode delivers around 500 mAh/g at 1 A/g current load. The remarkable cycle performance of Sample 2 is believed to be related to the superior chemical, structural, and physical properties of the electrode active material.
  • Öge
    Effect of spray drying on physicochemical stability and antioxidant capacity of rosa pimpinellifolia fruit extract-loaded liposomes conjugated with chitosan or whey protein during in vitro digestion
    (Springer, 2024) Kasapoğlu, Kadriye Nur ; Gültekin-Özgüven, Mine ; Kruger, Johanita ; Frank, Jan ; Bayramoğlu, Pelin ; Barla-Demirkoz, Aslı ; Özçelik, Beraat ; 0000-0001-6070-4948 ; 0000-0002-2073-8075 ; 0000-0002-1810-8154 ; Gıda Mühendisliği
    Spray drying is a well-established, energy efficient, and scalable process widely used in the food industry, however it may lead to thermal degradation of susceptible compounds, such as (poly)phenols, resulting in biological activity loss to some extent. In this study, we aimed to improve the physicochemical stability and bioaccessibility of (poly)phenols from Rosa pimpinellifolia fruit extract (Rosa extract) loaded in liposomes by generating solid particles via spray drying. Liposomes were conjugated with chitosan (Ch) and whey protein (Wp) to optimize the biopolymer concentrations by monitoring mean particle diameter, polydispersity index, and surface charge. The mean diameter of liposomes ranged between 135 and 210 nm upon optimal addition of Ch (0.4%, w/v) and Wp (4.0%, w/v) which also increased the entrapment efficiency of (poly)phenols from 74.2 to 77.8% and 79.1%, respectively. After spray drying, about 65–76% of the antioxidant capacity were retained in biopolymer-conjugated liposomes (Ch or Wp) while the retention rate was 48% in only spray-dried extract (Rosa extract powder). Compared to unencapsulated Rosa extract, spray drying (Rosa extract powder) and conjugation with Ch (Ch-Lip powder) or Wp (Wp-Lip powder) significantly increased the bioaccessibility of (poly)phenols and preserved their antioxidant capacity. Based on the findings of this study, Ch- or Wp-conjugation of liposomes prior to spray drying could improve physicochemical stability and protect (poly)phenols loaded in liposomes against processing stress and passage through the digestive tract. Further in vitro and in vivo investigations on a variety of bioactive compounds may draw more attention to their potential as functional foods.
  • Öge
    Effects of egg on cake batter rheology and sponge cake texture
    (Wiley, 2024) Inanlar, Batuhan ; Altay, Filiz ; orcid.org/0000-0002-5484-866X ; Food Engineering
    The physical, rheological, and textural properties of cake batters and cakes made from three different eggs were studied. The compositions of the egg samples are significantly different (p < 0.05), except for their fat contents. The flow characteristics of the cake batters showed pseudoplastic behavior with time dependency. In the frequency sweep test, the G" values were lower than the G' values at low frequencies and vice versa at high frequencies. The G" values of the samples decreased with the water content of the egg samples. While the sample with the highest amount of water showed less viscous batter properties, it yielded a cake structure with more moisture and less hardness, chewiness, adhesiveness, cohesiveness, and springiness properties. The G' and G" moduli decreased for all cake batters in the temperature sweep tests. Eggs with high protein and low water contents should be preferred for consumer acceptance.
  • Öge
    Efficacy of atmospheric non-thermal plasma corona discharge under dry and wet conditions on decontamination of food packaging film surfaces
    (Wiley, 2024) Acar, Emine Gizem ; Doganoz, Dilan ; Çavdar, Deniz ; Karbancioglu-Guler, Funda ; Burlica, Radu ; Astanei, Dragos ; Olariu, Marius-Andrei ; Gunes, Gurbuz ; orcid.org/0000-0002-2948-3785 ; Gıda Mühendisliği
    Food packaging materials must be sterilized to prevent cross-contamination of the product. Non-thermal plasma (NTP) corona discharge can be an effective alternative sterilization method for packaging films. The inactivation efficiency atmospheric NTP corona discharge under dry and wet conditions against vegetative cells of Escherichia coli, Staphylococcus aureus and Bacillus subtilis, spores of B. subtilis and Clostridium sporogenes and fungal spores of Candida albicans, Penicillium expansum and Aspergillus niger on polymeric packaging films were studied. The maximum inactivation of these microorganisms was 5.58, 0.54, 1.51, 1.06, 2.47, 1.73, 2.80, 3.20 and 3.50 log, respectively. Microbial inactivation by the treatments was greatly enhanced under wet conditions. Gram-negative bacteria were found to be more sensitive to NTP, but spores were more resistant than vegetative bacterial cells. Although fungi were less susceptible than bacteria in dry treatments, they became more sensitive than the Gram-positive bacteria in wet treatments. Overall, plasma treatments under wet conditions achieved higher microbial inactivation and would be favourable over the dry treatment.
  • Öge
    Electrocatalytic performance of interconnected self-standing tin nanowire network produced by AAO template method for electrochemical CO2 reduction
    (Wiley, 2023) Er, Dilan ; Avcı, Burçak ; Ürgen, Mustafa ; orcid.org/0009-0008-2120-2994 ; orcid.org/0000-0003-3549-0049 ; Metalurji ve Malzeme Mühendisliği
    In this study, we used a specially designed aluminum anodic oxide (AAO) template technique to produce interconnected self-standing tin nanowire electrocatalysts having a high surface-to-volume ratio for CO2 reduction toward formate. These electrodes consisted of interconnected tin nanowires with 150 nm diameter and 7 μm length supported on 70–100 μm thick tin film. As prepared electrodes produced 6 times higher formate than the flat tin sheets, yet Faradaic efficiencies (FE%) were unsatisfactory. The main reason for low FE% is determined as the etching of native oxide on tin nanowires during hot alkali treatment to remove AAO and remnant aluminum. Porous anodic oxidation in 1 M NaOH solution was realized to recover tin oxides on the surface. Anodized tin nanowire electrocatalysts produced higher formate than anodized tin sheets, reaching FEformate% of ~87 at −1 V vs. RHE cathodic reduction potential. Moreover, while anodic oxide on flat tin flaked off the surface in 1 h, these electrodes preserved their integrity and formate production ability even after 12 h.
  • Öge
    Encapsulated phenolic compounds : clinical efficacy of a novel delivery method
    (Springer, 2024) Özkan, Gülay ; Ceyhan, Tuğçe ; Çatalkaya, Gizem ; Rajan, Logesh ; Ullah, Hammad ; Daglia, Maria ; Çapanoğlu, Esra ; 0000-0003-0335-9433 ; Gıda Mühendisliği Bölümü
    Encapsulation is a drug or food ingredient loaded-delivery system that entraps active components, protecting them from decomposition/degradation throughout the processing and storage stages and facilitates their delivery to the target tissue/organ, improving their bioactivities. The application of this technology is expanding gradually from pharmaceuticals to the food industry, since dietary bioactive ingredients, including polyphenols, are susceptible to environmental and/or gastrointestinal conditions. Polyphenols are the largest group of plants' secondary metabolites, with a wide range of biological effects. Literature data have indicated their potential in the prevention of several disorders and pathologies, ranging from simpler allergic conditions to more complex metabolic syndrome and cardiovascular and neurodegenerative diseases. Despite the promising health effects in preclinical studies, the clinical use of dietary polyphenols is still very limited due to their low bioaccessibility and/or bioavailability. Encapsulation can be successfully employed in the development of polyphenol-based functional foods, which may improve their bioaccessibility and/or bioavailability. Moreover, encapsulation can also aid in the targeted delivery of polyphenols and may prevent any possible adverse events. For the encapsulation of bioactive ingredients, several techniques are applied such as emulsion phase separation, emulsification/internal gelation, film formation, spray drying, spray-bed-drying, fluid-bed coating, spray-chilling, spray-cooling, and melt injection. The present review aims to throw light on the existing literature highlighting the possibility and clinical benefits of encapsulated polyphenols in health and disease. However, the clinical data is still very scarce and randomized clinical trials are needed before any conclusion is drawn.
  • Öge
    Encapsulation of black rice bran extract in a stable nanoemulsion : effects of thermal treatment, storage conditions, and in vitro digestion
    (American Chemical Society, 2024) Saleh, Mohamed N. ; Salam, Mohamed Abdelbaset ; Çapanoğlu, Esra ; 0000-0003-0335-9433 ; Gıda Mühendisliği
    This study aimed to improve the dispersibility of phenolic compounds from black rice bran through the encapsulation process within nanoemulsion. The study focused on assessing the stability of the nanoemulsions, which were prepared using a combination of surfactants with distinct hydrophilic–lipophilic balance (HLB) values and sunflower oil under different thermal treatments and storage conditions. The study revealed a significant correlation between the mixed surfactant HLB value and the nanoemulsions properties, including average particle size, polydispersity index (PDI), and ζ-potential. Specifically, an increase in the HLB value was associated with a decrease in the initial average particle size. The encapsulated polyphenols exhibited remarkable stability over a storage period of up to 30 days at different temperatures with no significant changes observed in particle size or PDI. The study also investigated the impact of different ionic strengths (0.2, 0.5, and 1.00 mol L–1 NaCl) on the physical stability and antioxidant black rice bran extract nanoemulsion, and the results revealed that adding NaCl influenced the particle size and surface charge of the nanoemulsions. Total phenolic content and DPPH results demonstrated a significant impact of salt concentration on antioxidant properties, with varying trends observed among the HLB formulations. Furthermore, the behavior of the encapsulated extracts during digestion was examined, and their antioxidant activity was evaluated.
  • Öge
    Enhanced production of gamma-aminobutyric acid in fermented carrot juice by utilizing pectin hydrolysate derived from pomegranate waste
    (Wiley, 2024) Devecioğlu, Dilara ; Kara, Didem ; Tapan, Rabia ; Karbancıoğlu-Güler, Funda ; Kahveci, Derya ; orcid.org/0000-0001-6681-0944 ; orcid.org/0000-0001-6576-0084 ; orcid.org/0000-0003-0450-5682 ; Gıda Mühendisliği
    In this study, a functional fermented beverage enriched with gamma-aminobutyric acid (GABA) was produced. To achieve this, the prebiotic abilities of pectin obtained from pomegranate peel and its enzymatic hydrolysates were evaluated. Additionally, a functional fermented beverage enriched with GABA was produced by fermenting carrot juice with pectin hydrolysates. First, pectin was obtained at a yield of 8.91% from pomegranate peels. Pectinase-catalyzed hydrolysis of the obtained pectin was applied using different enzyme concentrations and hydrolysis times, and the effect of these hydrolysates on the growth of Levilactobacillus brevis was determined. Although the Fourier transform infrared (FT-IR) spectra of the resulting hydrolysates were similar, their degree of esterification compared to that of pectin was statistically different (p < .05). Considering the viability analysis and GABA production of L. brevis in the liquid medium supplemented with pectin or its hydrolysate, the hydrolysate obtained by treatment with 400 μL enzyme for 2 h and having a high glucose content (216.80 mg/100 g) was selected for application in fermented carrot juice. During fermentation (24, 48, and 72 h), a remarkable change was observed, especially in the amounts of lactic acid and malic acid, while the amount of GABA in carrot juice varied between 25 and 46 mg/mL and increased with the increase in hydrolysate concentration. It was observed that the total phenolic content and antioxidant activity of carrot juice were highly affected by the hydrolysate concentration. This study demonstrated that pectin hydrolysate obtained from food waste could be a potential prebiotic and could be used in the production of a functional beverage with improved GABA content.
  • Öge
    Enhancing the sustainability of Poly(lactic acid) (PLA) through ketene-based chain extension
    (Springer, 2024) Alkan Göksu, Yonca ; Metalurji ve Malzeme Mühendisliği
    The widespread utilization of nonrenewable fossil-based polymers has led to significant environmental damage. Bio-based Poly(lactic acid) (PLA) has garnered substantial academic and industrial interest in the last two decades due to its advantageous characteristics for food packaging applications. Nonetheless, the improper disposal of PLA continues to contribute to the plastic waste problem. PLA recycling mainly involves thermal processes, facing challenges due to PLA’s limited stability. This study aims to enhance PLA’s molecular weight and melt viscosity by using chain extenders to increase its degree of branching. A modular chain extender capable of thermally forming highly reactive ketene intermediates is employed to react with PLA’s hydroxyl and carboxyl end groups in a single step. For this purpose, copolymers of styrene and 2,2,5-trimethyl-5-(4-vinylbenzyl)-1,3-dioxane-4,6-dione were synthesized using free radical polymerization and characterized through 1H-NMR, TGA, and DSC analyses. The chemical interaction between these chain extenders and molten PLA was also explored, resulting in increased PLA molecular weight and higher melting temperature (Tm), reaching 155.1 for PLA_2.5CE2. Additionally, the branching introduced through this process led to a notable increase in the UV absorption of PLA, suggesting potential applications in the packaging industry. The chemical tunability of this functional ketene-based chain extender holds promise for tailoring PLA’s structure for diverse applications, further advancing its sustainability and utility.
  • Öge
    Evaluation of experimental and economic potential of industrial borax aqueous solution by eutectic freeze crystallization method
    (American Chemical Society, 2024) Okumuş Ermiş, Ayşe Gül ; Kenar, Mehmet Emre ; Genceli Güner, Fatma Elif ; https://orcid.org/0000-0001-6201-6719 ; Kimya Mühendisliği
    In industry, various compounds are derived from boron minerals, and the production and processing of these minerals produce various waste materials. Boron production and the discharge of boron waste streams pose a significant threat to the environment. The goal of future process technologies is to recover water and boron minerals from process effluents and minimize waste. The eutectic freeze crystallization (EFC) method stands out as a promising candidate to offer an alternative solution to this problem. This study evaluates the possibility of using EFC technology for an industrial borax system for the first time. The eutectic point of Na2B4O7–H2O is determined. Moreover, the study delves into the crystal sizes, appearances, growth rates, and impurities of both ice and borax (Na2B4O7·10H2O) salt crystals. The successful application of the EFC method for the recovery of water and Na2B4O7·10H2O salt from an industrial waste solution has been achieved. Finally, a treatment facility dedicated to borax, employing EFC for the separation of industrial waste borax solution, has been designed. Additionally, an economic evaluation has been conducted. The analysis showed that the payback time for this investment is 9.2 years, and 78% conversion of liquid waste from the industrial borax waste stream to pure borax and water is possible. Thus, attractive EFC technology succeeds in approaching a zero-waste stream by converting waste into raw materials.
  • Öge
    Fabrication of MIL-101(Fe)-embedded biopolymeric films and their biomedical applications
    (Springer, 2024) Kocaağa, Banu ; Bağımsız, Gamze ; Alev, İbrahim Avni ; Miavaghi, Mehran Aliari ; Sirkecioğlu, Ahmet ; Batirel, Saime ; Güner, Fatma Seniha ; Kimya Mühendisliği
    The development of wound-dressing materials with superior therapeutic effects, controlled bioactive agent release, and optimal mechanical properties is crucial in healthcare. This study introduces innovative hydrogel films designed for the sustained release of the local anesthetic drug Procaine (PC), triggered by pH changes. These films are composed of MIL-101(Fe) particles and pectin polymers. MIL-101(Fe) was chosen for its high surface area, stability in aqueous environments, and biocompatibility, ensuring low toxicity to normal cells. MIL-101(Fe)-embedded-pectin hydrogels were synthesized and characterized using Fourier-transformed infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma (ICP) spectrometry, particle size analysis, and goniometry. Rheological analysis assessed the hydrogels’ viscoelastic behavior, and UV-spectrophotometry was utilized for drug loading and release studies. The hydrogels exhibited shear-thinning properties, enhancing shape adaptability and recovery, crucial for wound-dressing applications. Controlled drug release was achieved by maintaining the PC solution’s pH between 8.2 and 9.8 during the drug-loading step. The hydrogel film’s impact on wound healing was evaluated through an in vitro wound healing assay, and cytotoxicity was assessed using a WST-1 cell proliferation assay with human dermal fibroblast cells. Results demonstrated that pectin composites enhance cell viability and support fibroblast cell migration without adverse effects, indicating their potential for effective wound healing applications. This study highlights the potential of MIL-101(Fe)-embedded-pectin hydrogels in advancing wound care technology.
  • Öge
    Identifying and assessing putative allosteric sites and modulators for CXCR4 predicted through network modeling and site identification by Ligand Competitive Saturation
    (American Chemical Society, 2024) İnan, Tuğçe ; Flinko, Robin ; Lewis, George K. ; MacKerell, Alexander D., Jr. ; Kürkçüoğlu, Özge ; 0000-0001-8287-6804 ; 0000-0003-0228-3211 ; Kimya Mühendisliği
    The chemokine receptor CXCR4 is a critical target for the treatment of several cancer types and HIV-1 infections. While orthosteric and allosteric modulators have been developed targeting its extracellular or transmembrane regions, the intramembrane region of CXCR4 may also include allosteric binding sites suitable for the development of allosteric drugs. To investigate this, we apply the Gaussian Network Model (GNM) to the monomeric and dimeric forms of CXCR4 to identify residues essential for its local and global motions located in the hinge regions of the protein. Residue interaction network (RIN) analysis suggests hub residues that participate in allosteric communication throughout the receptor. Mutual residues from the network models reside in regions with a high capacity to alter receptor dynamics upon ligand binding. We then investigate the druggability of these potential allosteric regions using the site identification by ligand competitive saturation (SILCS) approach, revealing two putative allosteric sites on the monomer and three on the homodimer. Two screening campaigns with Glide and SILCS-Monte Carlo docking using FDA-approved drugs suggest 20 putative hit compounds including antifungal drugs, anticancer agents, HIV protease inhibitors, and antimalarial drugs. In vitro assays considering mAB 12G5 and CXCL12 demonstrate both positive and negative allosteric activities of these compounds, supporting our computational approach. However, in vivo functional assays based on the recruitment of β-arrestin to CXCR4 do not show significant agonism and antagonism at a single compound concentration. The present computational pipeline brings a new perspective to computer-aided drug design by combining conformational dynamics based on network analysis and cosolvent analysis based on the SILCS technology to identify putative allosteric binding sites using CXCR4 as a showcase.
  • Öge
    Investigation of the effects of titanium oxide concentration on the sinterability, microstructural characteristics, mechanical properties, in vitro bioactivity, and cell culture behavior of chicken-derived hydroxyapatite
    (Springer, 2024) Gökçe, Hasan ; 0000-0001-7892-5642 ; Prof. Dr. Adnan Tekin Malzeme Bilimleri ve Üretim Teknolojisi UYG-AR Merkezi
    This study focuses on how titanium oxide (TiO2) in concentrations ranging from 0.5 to 4% by weight added the hydroxyapatite (CHA) made from chicken femur bones’, affects sinterability, microstructural, mechanical, and in vitro bioactivity properties. According to the results of the experiments, it was determined that CHA decomposed into whitlockite, alpha tricalcium phosphate (α-TCP), tetracalcium phosphate (TTCP), and calcium oxide (CaO) phases at different temperatures. Rutile and perovskite (CaTiO3) phases were also found in TiO2 added CHAs in addition to these phases. With increasing sintering temperature of CHA, the diameters and the heights of the samples decreased. Density increased up to 1250 °C and decreased at 1300 °C respectively. while the partial density value showed similar behavior with density and hardness, At 1200 °C, the maximum values of fracture toughness (1.071 MPam1/2) and compressive strength (145.417 MPa) were attained; however, as sintering temperatures increased, these values shifted downward to 0.882 MPam1/2 and 111.096 MPa, respectively. It has been determined that grain growth and decomposition are the underlying factors in obtaining the highest density, hardness, fracture toughness and compressive strength values for CHA at different temperatures. Among the TiO2 added CHAs, the best properties are obtained for CHA-0.5TiO2 sintered at 1300 °C (Density: 3.0057 g/cm3, Hardness: 3.973 GPa, Fracture toughness: 1.583 MPam1/2 and Compressive strength: 170.045 MPa) and the properties of the CHA-TiO2 composite decreased with increasing TiO2 ratio. This is due to the fact that increasing TiO2 has a detrimental impact on CHA’s sinterability behavior and causes it to become more porous and degrade more quickly. It was discovered through in vitro bioactivity and cell culture assays that the addition of TiO2 had a detrimental impact on the proliferation of bone tissues.
  • Öge
    İTÜ Kimya Mühendisliği 1. Lisansüstü Sempozyumu Özet Kitabı 26 Nisan 2019, İstanbul
    (İTÜ, 2019-04-26) Kimya Mühendisliği ; Gümüşlü Gür, Gamze ; Genceli Güner, Fatma Elif