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Öğe Design of highly selective, and sensitive screen-printed electrochemical sensor for detection of uric acid with uricase immobilized polycaprolactone/polyethylene imine electrospun nanofiber(Pergamon-Elsevier Science Ltd, 2023) Muhammad, Fakhriy; Dik, Gamze; Kolak, Seda; Gedik, Kubra Karadas; Bakar, Busra; Ulu, Ahmet; Ates, BurhanUric acid (UA) plays a significant role in nerve center, human metabolism, and kidney system. Therefore, it is necessary to establish a simple, rapid, and sensitive detection method for UA. In recent years, researchers have been highly attracted by nanomaterials with satisfactory functions in electrochemical applications. In this study, polycaprolactone (PCL)/polyethylene imine (PEI) nanofiber membranes were prepared and used for the immobilization of uricase (UOx). The prepared membranes were characterized in terms of structure, composi-tion, and morphology. Afterward, the quantum dot screen printed electrode (QD SPCE) was modified with PCL/ PEI nanofiber membranes with and without methylene blue (MB) as an electron mediator. The electrochemical performance of the developed sensors was investigated by cyclic voltammetry (CV), differential pulse voltam-metry (DPV), and electrochemical impedance spectroscopy (EIS). Under the optimal conditions, the modified sensors provided a broad linear range (5.0-52.0 mu M) for the electrochemical detection of UA. Limit of detection (LoD) values were determined as 3.96 mu M and 1.85 mu M for the PCL/PEI/UOx/QD SPCE and PCL/PEI/UOx/MB/ QD SPCE, respectively. The four-week stability results showed the change in current for the PCL/PEI/UOx/QD SPCE and PCL/PEI/UOx/MB/QD SPCE to be 92% and 87%, respectively. Additionally, in the mixed interference test remaining current ratios for UA were 95% and 82% for the PCL/PEI/UOx/QD SPCE and PCL/PEI/UOx/MB/ QD SPCE, respectively. Most importantly, the effectiveness of the electrodes was also verified in real sample detection with satisfactory recovery (similar to 98-112%). Overall, the results showed that the PCL/PEI/UOx/QD SPCE and PCL/PEI/UOx/MB/QD SPCE have the advantages of simplicity, high sensitivity, and good selectivity for UA determination.Öğe Effects of drugs commonly used in Sars-CoV-2 infection on renal tissue in rats(2023) Yıldız, Azibe; Ozhan, Onural; Vardi, Nigar; Akyuz, Mustafa; Bakar, Busra; Ulu, Ahmet; Taslıdere, ElifAim: In December 2019, the coronavirus disease was caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Some drugs were repurposed for this disease treatment. Hydroxychloroquine (HCQ), favipiravir (FAV), molnupiravir (MOL), and dexamethasone (DEX) were widely used for the treatment of the disease. To increase the success of the treatment of coronavirus disease, there was used some of these drugs in combination. On the other hand, limited studies report these drugs’ side effects. Therefore, this study was designed to evaluate the possible effects of these drugs and their combinations on the kidney tissues of rats without viral load. Materials and Methods: Male Wistar albino rats were divided into control, HCQ, FAV, HCQ+FAV, HCQ+FAV+DEX, MOL, and MOL+DEX groups. At the end of the experiment, the serum kidney tissue samples were taken. Serum samples were analyzed for urea and creatinine. Kidney tissue samples were assessed as histopathological and immunohistochemical for heat shock protein 60 (HSP60), caspase-3, and receptor-interacting protein kinase-3 (RIPK3). Results: Urea and creatinine levels were within the normal range in all groups. Histopathologically, all drugs and their combinations caused tubular degeneration. On the other hand, histopathological alterations were more prominent in the HCQ group. The oxidative stress marker HSP60 was significantly increased in FAV, MOL, and MOL+DEX groups, while it was similar to the control group in the HCQ groups. Apoptosis marker caspase-3 expression was found to be prominently higher in other drug groups except the FAV group. Expression of RIPK3, a marker of necroptosis, was significantly increased in all drug groups. Conclusion: Taken together, the data of our study show that the administration of all drugs alone and in combination may cause structural damage to the kidney. Furthermore, our results indicate that HCQ can exhibit more damaging effects compared to other drugs.Öğe Effects of the apricot diets containing sulfur dioxide at different concentrations on rat testicles(Springer Heidelberg, 2023) Yildiz, Azibe; Ozhan, Onural; Ulu, Ahmet; Dogan, Tugba; Bakar, Busra; Ugur, Yilmaz; Taslidere, ElifDue to its antioxidant and antimicrobial properties, sulfur dioxide (SO2) is widely used in foods and beverages to prevent the growth of microorganisms and to preserve the color and flavor of fruits. However, the amount of SO2 used in fruit preservation should be limited due to its possible adverse effects on human health. The present study was designed to investigate the effects of different SO2 concentrations in apricot diets on rat testes. Animals were randomly divided into six groups. The control group was fed a standard diet, and the other groups were fed apricot diet pellets prepared with (w/w) 10% dried apricots containing SO2 at different concentrations (1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, and 3500 ppm/kg) for 24 weeks. After sacrification, testicles were evaluated biochemically, histopathologically, and immunohistopathologically. Our results showed that an apricot diet containing 1500 ppm and 2000 ppm SO2 did not cause significant changes in testis. However, it was determined that tissue testosterone levels decreased as the amount of SO2 (2500 ppm and above) increased. Apricot diet containing 3500 ppm SO2 caused a significant increase in spermatogenic cell apoptosis, oxidative damage, and histopathological changes. In addition, a decrease in the expression of connexin-43, vimentin, and 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) was observed in the same group. In summary, the results show that sulfurization of apricot at high concentrations such as 3500 ppm may lead to male fertility problems in the long term through mechanisms such as oxidative stress, spermatogenic cell apoptosis, and inhibition of steroidogenesis.Öğe Facile construction of a robust and recyclable laccase/metal-organic framework-808 with boosted stability for biodegradation of Reactive Blue 171 and Reactive Blue 198 from aqueous media(Elsevier, 2024) Bakar, Busra; Bugday, Nesrin; Birhanli, Emre; Boran, Filiz; Ulu, Ahmet; Yasar, Sedat; Yesilada, OzferLaccase enzyme sees application demand in many industries such as textile, food processing, wood processing, pharmaceutical, and chemical. However, it becomes difficult to maintain the enzymatic activity of laccase under harsh reaction conditions and even after several biocatalytic cycles. Therefore, suitably prescribed supports are crucial to ensure that the catalytic activity and reusability of the immobilized laccase are maintained at high levels. The present study highlights the development and dye decolorization application of an enzyme carrier matrix employing a Zr-based metal-organic framework (MOF), MOF-808, with hierarchical porosity for the immobilization of laccase from Trametes trogii . The immobilization efficiency for Lac/MOF-808 was found to be 70.83 +/- 1.98 %. Lac/MOF-808 exhibited optimal catalytic temperature at 60 degrees C, while the optimal catalytic pH was 4.5. Due to recoverable properties from the carrier matrix the recycle test was satisfactory for the Lac/MOF808, being reused 7 times without losses greater than 50 % of residual activity. Stored at 25 degrees C, Lac/MOF-808 retained 30 % of its activity during 4-weeks period. A kinetic study was carried out for Lac/MOF-808 monitoring the oxidation reaction of ABTS. The K-m value was 0.070 mM and the V-max was 87.7 mu mol min(-1) g(-1). Kinetic investigations, on the other hand, demonstrated a decrease in K m following immobilization, signifying a higher affinity for substrate. The Lac/MOF-808 maintained its decolorization efficiency even after eight reaction cycles, exhibiting a remarkable activity of 56.7 % and 77.2 % against Reactive Blue 171 and Reactive Blue 198, respectively. Hence, the described Lac/MOF-808 might be an ideal candidate for efficient dye decolorization applications.Öğe Horseradish Peroxidase Immobilized onto Mesoporous Magnetic Hybrid Nanoflowers for Enzymatic Decolorization of Textile Dyes: A Highly Robust Bioreactor and Boosted Enzyme Stability(Amer Chemical Soc, 2024) Bakar, Busra; Akbulut, Mustafa; Ulusal, Fatma; Ulu, Ahmet; Ozdemir, Nalan; Ates, BurhanRecently, hybrid nanoflowers (hNFs), which are accepted as popular carrier supports in the development of enzyme immobilization strategies, have attracted much attention. In this study, the horseradish peroxidase (HRP) was immobilized to mesoporous magnetic Fe3O4-NH2 by forming Schiff base compounds and the HRP@Fe3O4-NH2/hNFs were then synthesized. Under optimal conditions, 95.0% of the available HRP was immobilized on the Fe3O4-NH2/hNFs. Structural morphology and characterization of synthesized HRP@Fe3O4-NH2/hNFs were investigated. The results demonstrated that the average size of HRP@Fe3O4-NH2/hNFs was determined to be around 220 nm. The zeta-potential and magnetic saturation values of HRP@Fe3O4-NH2/hNFs were -33.58 mV and similar to 30 emu/g, respectively. Additionally, the optimum pH, optimum temperature, thermal stability, kinetic parameters, reusability, and storage stability were examined. It was observed that the optimum pH value shifted from 5.0 to pH 8.0 after immobilization, while the optimum temperature shifted from 30 to 80 degrees C. K-m values were calculated to be 15.5502 and 7.6707 mM for free HRP and the HRP@Fe3O4-NH2/hNFs, respectively, and V-max values were calculated to be 0.0701 and 0.0038 mM min(-1). The low K-m value observed after immobilization indicated that the affinity of HRP for its substrate increased. The HRP@Fe3O4-NH2/hNFs showed higher thermal stability than free HRP, and its residual activity after six usage cycles was approximately 45%. While free HRP lost all of its activity within 120 min at 65 degrees C, the HRP@Fe3O4-NH2/hNFs retained almost all of its activity during the 6 h incubation period at 80 degrees C. Most importantly, the HRP@Fe3O4-NH2/hNFs demonstrated good potential efficiency for the biodegradation of methyl orange, phenol red, and methylene blue dyes. The HRP@Fe3O4-NH2/hNFs were used for a total of 8 cycles to degrade methyl orange, phenol red, and methylene blue, and degradation of around 81, 96, and 56% was obtained in 8 h, respectively. Overall, we believe that the HRP@Fe3O4-NH2/hNFs reported in this work can be potentially used in various industrial and environmental applications, particularly for the biodegradation of recalcitrant compounds, such as textile dyes.Öğe Immobilization of ?-Amylase onto Quantum Dots Prepared from Hypericum perforatum L. Flowers and Hypericum capitatum Seeds: Its Physicochemical and Biochemical Characterization(Springer/Plenum Publishers, 2023) Acari, Idil Karaca; Dik, Gamze; Bakar, Busra; Ulu, Ahmet; Onal, Yunus; Ates, BurhanEnzyme immobilization is an effective way to increase the catalytic activity and stability of the alpha-amylase (Amy) enzyme for industrial uses. For this purpose, carbon and graphene quantum dot (QDs) structures were prepared from Hypericum perforatum L. flowers (QD-1), and Hypericum capitatum seeds (QD-2) obtained from an herbalist in Hatay province of Turkey. Structural and morphological characterization of the prepared QDs and QDs/Amy were carried out by Fourier transform infrared spectrophotometer (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray (EDX). Meanwhile, biochemical characterizations such as optimum pH and temperature, kinetic parameters, effects of metal ions, organic solvents, and trypsin digestion on enzyme activity were performed and compared with free Amy. The Amy enzyme was immobilized with an activity efficiency of 71.15% for QD-1/Amy, and 81.51% for QD-2/Amy under optimal conditions. The difference in activity efficiency between QD-1/Amy and QD-2/Amy was likely due to a change in the surface porosity of QDs structures. While the optimal pH value of all three forms of Amy was recorded as 6.0, their optimal temperature was found to be 40 degrees C. The activation energy (E-a) of the free Amy was found to be 4.81 kJ/mol, while it was 9.61 kJ/mol, and 3.20 kJ/mol for QD-1/Amy, and QD-2/Amy, respectively. K-m values were calculated as 1.18, 1.57, and 1.35 mg/mL for free Amy, QD-1/Amy, and QD-2/Amy, respectively, and V-max values were calculated as 37.52, 37.60, and 39.93 mu mol/min, respectively. Kinetic data revealed that the immobilized enzymes had lower substrate affinity compared to the free Amy. Besides, the QD-1/Amy and QD-2/Amy exhibited more stability than free Amy against metal ions, organic solvents as well as trypsin digestion due to the increment in conformational rigidity caused by changes in the secondary structures of the immobilized enzyme. For instance, after incubation with trypsin for 120 min, free Amy, QD-1/Amy, and QD-2/Amy retained approximately 20%, 35%, and 26% of initial activities, respectively. Finally, it can be proposed that the prepared carriers in this work may a useful to produce stable and active immobilized Amy to be used in industrial applications.Öğe Immobilization of Trametes trogii laccase on polyvinylpyrrolidone-coated magnetic nanoparticles for biocatalytic degradation of textile dyes(Taylor & Francis Ltd, 2024) Bakar, Busra; Birhanli, Emre; Ulu, Ahmet; Boran, Filiz; Yesilada, Ozfer; Ates, BurhanHigh cost and low operational stability are the most important challenges limiting the possible use of laccase in the removal of textile dyes. To overcome these challenges, in this study, polyvinylpyrrolidone (PVP)-coated magnetic nanoparticles (MNPs) were produced and characterized. To our knowledge, this is the first study to explore the feasibility of immobilizing a Trametes trogii laccase enzyme on Fe3O4/PVP MNPs. The characterization of samples and the successful immobilization of laccase were verified by characterization methods. Besides, the biochemical properties and stability of the Fe3O4/PVP/Lac were evaluated in terms of optimum pH, optimum temperature, thermostability, thermodynamic and kinetic parameters, storage stability, operational stability, and decolorization efficiency of two different textile dyes. The optimum activities were recorded at pH 2.5 degrees C and 30 degrees C. The Fe3O4/PVP/Lac displayed remarkable thermal stability and activation energy for denaturation, enthalpy, Gibbs free energy, and entropy results confirmed the enhanced stability of Fe3O4/PVP/Lac against high temperatures. Meanwhile, the Fe3O4/PVP/Lac retained about 58% of its original activity after seven consecutive reuses, while it retained up to 25% of its original activity after 28 d of storage at room temperature. K-m and V-max for the Fe3O4/PVP/Lac were calculated to be 126 mu M and 211 mu mol/min, respectively. Finally, after 8 and 6 cycles of repeated use, the Fe3O4/PVP/Lac still decolorized 32.34% and 32.23% of Remazol Brilliant Blue R (RBBR) and Indigo Carmine (IC), respectively. As envisioned, this study suggests a promising way to solve the problems of high price and poor operational stability of the enzyme during biocatalytic decolorization of textile dyes in wastewaters.Öğe Immobilization of Xylanase into Zeolitic Imidazolate Framework-67 (ZIF-67) and Manganese-Doped ZIF-67 (Mn/ZIF-67): A Comparison Study(Springer/Plenum Publishers, 2024) Bakar, Busra; Dik, Gamze; Ulu, Ahmet; Ates, BurhanIt has been discovered that metal-organic frameworks (MOFs) have desirable qualities for the immobilization of enzymes, including a high surface area, significant interior pore volumes, and easily changeable pore size. Herein, the xylanase (Xyl) enzyme was immobilized for the first time to two different carrier supports, zeolitic imidazolate framework-67 (ZIF-67) and manganese-doped ZIF-67 (Mn/ZIF-67) by in situ method. The physicochemical characterizations of MOFs with and without Xyl were performed by FT-IR, XRD, SEM, and EDAX techniques. Xyl@ZIF-67 and Xyl@Mn/ZIF-67 were evaluated in terms of optimum temperature, optimum pH, kinetic parameters, thermal stability, reusability as well as juice clarification and compared with free Xyl. Optimum temperature values were 50 degrees C for Xyl@ZIF-67 and 70 degrees C for free Xyl and Xyl@Mn/ZIF-67. Optimum pH values for free Xyl, Xyl@ZIF-67, and Xyl@Mn/ZIF-67 were recorded as 6.0, 8.0, and 7.0, respectively. Km values for free Xyl, Xyl@ZIF-67, and Xyl@Mn/ZIF-67 were calculated as 3.139, 5.430, and 0.799 mg/mL, respectively, while Vmax values were calculated as 0.167, 0.226, and 0.062 mu mol/min/mL, respectively. The results revealed that in comparison to the free Xyl, Xyl@ZIF-67, and Xyl@Mn/ZIF-67 exhibited more thermal resistance. After incubation at 70 degrees C for 120 min, the free Xyl remained at 28.7% of the activity, while the Xyl@ZIF-67 and Xyl@Mn/ZIF-67 remained at 85.7% and 40.0%, respectively. Moreover, after eight cycles, the Xyl@ZIF-67 and Xyl@Mn/ZIF-67 retained more than 70% of their initial activity. Further, the transmittance of apple juice was increased from 65.61 to 94.73% and from 77.80 to 84.13%, respectively, when Xyl@ZIF-67 and Xyl@Mn/ZIF-67 were used as biocatalysts. Overall, these findings indicated that the suggested Xyl@ZIF-67 and Xyl@Mn/ZIF-67 have a high potential for juice clarification as an efficient heterogeneous biocatalyst.Öğe Immobilization of Xylanase onto Starch Nanoparticles: A Reusable and Robust Nanobiocatalyst for Juice Clarification(Wiley-V C H Verlag Gmbh, 2023) Dik, Gamze; Bakar, Busra; Ulu, Ahmet; Koytepe, Sueleyman; Ates, BurhanNanoparticles (NPs) have attracted interest recently as a promising support for the immobilization of enzymes.Xylanase (Xyl) has been utilized in the food industry for several purposes. To improve its stability and reusability,starch NPs (SNPs)are synthesized and assessed for Xyl immobilization for the first time. . The characterization results reveal that SNPs are successfully synthesized and Xyl@SNPs are effective as the immobilization carrier. The Xyl is immobilized on SNPs under optimized conditions leading to 91% immobilization efficiency. A shift in optimum pH (from 6.0 to 8.0) and temperature (from 70 to 60 degrees C) of Xyl is observed after immobilization. The Xyl@SNPs possess improve pH stability and thermal stability as well as operational stability. The Xyl@SNPs are easily reutilized and the residual activity is still higher than 62% after seven times. More importantly, the Xyl@SNPs have a lower Km value and enhance affinity for the substrate compared to the free Xyl. Additionally, the clarity of orange juice is increased by 76.0% by using Xyl@SNPs after 2 h incubation at 60 degrees C, pH 8.0. These positive results show promising support for the Xyl immobilization of SNPs, confirming that this immobilized enzyme-based strategy is an effective technique for rapid clarification of targeted juices.Öğe Investigation of some biochemical parameters of wild and culturedMyrtus communisL. fruits subjected to different conservation methods(Springer, 2021) Cakmak, Meltem; Bakar, Busra; Ozer, Dursun; Geckil, Hikmet; Karatas, Fikret; Saydam, SinanIn this study, wild and cultivated whiteMyrtus communisL. (myrtle) fruits were investigated for their vitamin levels (A, B, C and E), carotenes (lycopene, beta-carotene), functional peptides (glutathione, ghrelin), oxidative stress markers (GSSG and MDA), total phenolic and flavonoid substances, antioxidant capacity (DPPH, TEAC) and essential elements (Se, Zn, Fe, Cu and Mn). The results showed that both myrtle fruits can be considered as the good source of vitamins, antioxidants and elements. The preservation (sun or microwave-drying) methods for this seasonal fruit caused a significant (p < 0.05) decrease in their biochemical and bio-pharmacological content compared to fresh or frozen fruits. On the contrary, preservation resulted a significant increase in GSSG and MDA levels. The amounts of Se, Zn, Fe, Cu and Mn in wild myrtle fruit were found as 0.58, 205, 228.0, 37.22 and 24.3 mu g/g dw, respectively.Öğe Propelling of Enzyme Activity by Using Different Triggering Strategies: Applications and Perspectives(Amer Chemical Soc, 2023) Dik, Gamze; Bakar, Busra; Ulu, Ahmet; Ates, BurhanEnzymes have been widely used as biocatalysts to meet the increasing demand for industrial approaches. Even if the method of immobilization used to stabilize enzymes seems easy and effective for scientists, the maintenance of activity remains currently an open challenge in various applications. Activity enhancement has recently gained a huge interest since this is a significant point in terms of industrial applications. In this context, external stimulants such as ultrasound, magnetic field, electric field, and light irradiation affect the activity of an enzyme in different aspects. Among these, ultrasound induction exhibits a prominent role in the enhancement of the activity of the immobilized enzyme. On the other hand, although a large number of articles have reported improvements in the catalytic activities of enzymes by induction methods, to the best of our knowledge, a review describing these improvements in the catalytic activities of enzymes has not yet been reported. Therefore, this novel review focused on the effects of the different induction methods, and it will provide novel perspectives and recent information for the development and application of related research areas. In addition, it will give an insight into the mechanisms at the molecular level in response to the question of how the induction methods enhance enzyme activity.
