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https://hdl.handle.net/20.500.12451/791

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Structural characteristics of Lacticaseibacillus rhamnosus ACS5 exopolysaccharide in association with its antioxidant and antidiabetic activity in vitro
(Elsevier B.V., 2024) İnanan, Tulden; Önal Darılmaz, Derya; Karaduman Yeşildal, Tuğçe; Yavuz, Serkan
A novel structure of exopolysaccharide from the Lactic Acid Bacteria (LAB) Lacticaseibacillus rhamnosus ACS5, isolated from home-made Turkish cheese, is described. After lyophilization, the L-EPS-ACS5 was characterized in production and functional activities in vitro, including antioxidant and antidiabetic activities. The physicochemical characterizations of the L-EPS-ACS5 were determined through molecular weight, UV, FTIR, SEM, TGA, HPLC, NMR, methylation, and GC–MS analysis. Strong antioxidant activities of L-EPS-ACS5 were confirmed from the results obtained in the hydroxyl radical, DPPH, ABTS, FRAP, superoxide anion radical, total antioxidant activity, and DNA damage protective effect, and also the L-EPS-ACS5 exhibited high antidiabetic activity (60 %). This study isolated L-EPS-ACS5 from a home-made cheese L. rhamnosus strain, demonstrating its novel and enhanced functionalities compared to existing strains. This opens exciting avenues for its development in the fields of biomedicine and pharmaceuticals.
Phenolic Content Analysis of Two Species Belonging to the Lamiaceae Family: Antioxidant, Anticholinergic, and Antibacterial Activities
(Multidisciplinary Digital Publishing Institute (MDPI), 2024) Ndhlala, Ashwell R.; Işık, Mesut; Kavaz Yüksel, Arzu; Dikici, Emrah
The Lamiaceae family are utilized as ornamental, medicinal, and food supplements throughout the world. The current study focuses on a comparative analysis of the phenolic compositions and bioactivities (including antioxidant, anticholinergic, and antibacterial activities) of ethanolic extracts derived from the aerial parts of the two species (Lavandula stoechas L. and Thymus sipyleus Boiss). The presence of phenolic compounds and phytochemicals in the plant extracts was identified using the LC-MS/MS technique. The LC-MS/MS analysis revealed that vanillic acid (125,596.66 µg/L) was the most abundant phytochemical in L. stoechas. Kaempferol (8550.52 µg/L) was the most abundant substance in Thymus sipyleus. The assessment of the antioxidant efficacy of the species extracts was conducted using the DPPH (2.2-diphenyl-1-picryl-hydrazyl-hydrate), ABTS (2.2?-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)), Fe3+–Fe2+ reducing, and CUPRAC (Cu2+–Cu+ reducing) assays. The anticholinergic activity of the samples was determined using the acetylcholinesterase (AChE) inhibition assay. The results of antioxidant activity were higher in the T. sipyleus than in the L. stoechas ethanol extracts. The extracts of L. stoechas exhibited radical scavenging activity ranging from 15 to 18%, while T. sipyleus had activity effects ranging from 34% to 38%. The AChE inhibition potential for L. stoechas and T. sipyleus extracts as IC50 values were 0.221 ± 0.01 mg/mL and 0.067 ± 0.02 mg/mL, respectively. The antibacterial effects of the ethanolic extracts of these species against pathogenic bacteria isolates were determined using the MIC (minimal inhibitory concentration) method. These findings indicated that the extracts from L. stoechas and T. sipyleus possess the potential to be natural antioxidants in the realm of food preservation. Additionally, their antioxidant, anticholinergic, and antimicrobial properties suggest potential therapeutic utility in the management of certain diseases.
Molecular imprinted polymers: important advances in biochemistry, biomedical and biotechnology
(Springer Science and Business Media Deutschland GmbH, 2024) Önal Acet, Burcu; İnanan, Tülden; Salieva, Kalipa; Borkoev, Bakyt; Odabaşı, Mehmet; Acet, Ömür
Molecularly imprinted polymers (MIPs) are handmade receptors that mimic the binding of natural antibodies. In other words, MIPs can selectively bind to the target molecule and qualify as bio-inspired synthetic materials. Today, MIPs are used extensively and are being developed further for biological applications. High cost and time consuming techniques are compelling factors for the field of biochemistry, biomedicine and biotechnology (3B), and there is an urgent need for an alternative, cheap, easy to produce, fast and effective method in these fields. MIPs stand out as a promising way for this purpose. MIPs have superiorities such as specific recognition specificity, excellent sensitivity selectivity and reusability. From this point of view, we examined MIP-related drug delivery studies, cell recognition, enzyme applications, in vivo applications, and applications for some important biomolecules. The aim of this review is to compile the utilizations, advantages, important developments and future expectations of MIPs for the fields of 3B.
The influence of salinity in drinking water on nitrate/nitrite removal through sulfur-driven autotrophic denitrification
(Elsevier Ltd, 2024) Öztürk, Arzu
It is a known fact that access to drinking water is becoming more difficult all over the world. Excessive consumption of water causes increased salinity in existing resources. Therefore, it is necessary to develop economical and efficient treatment methods for both nitrogen removal and against salting in order to access safe drinking water. The present study analyses the effect of salinity on the process performance of sulfur-based autotrophic denitrification/denitritation, which is a low-cost and efficient method for drinking water purification. The bioreactor was operated under different salt concentrations (0.05–4 % or 0.5–40 g NaCl/L), nitrate/nitrite loading rates (NLR) (0.033–0.62 gNO3-N/(L.d)), and hydraulic retention times (HRTs) (18–8 h). Even at a high salt concentration such as 4 % NaCl, which is not very common in drinking water, denitrification (nitrate removal efficiency (NRE) 99.36 %) was found to occur smoothly. NRE decreased by up to 33 % at low HRT values (8 h). Compared to denitrification, denitritation performance was higher and no negative effect of salt concentration was observed. Sulfur-based autotrophic denitrification/denitritation process was found to be highly effective in nitrate and nitrite removal from salt water.
Fabrication of nano-sized Pd catalyst supported on sodium carboxymethyl cellulose/gum Arabic/sodium alginate functionalized microspheres for catalytic reduction of nitro compounds, organic dyes, K3[Fe(CN)6], and chromium(VI) pollutants
(Elsevier B.V., 2024) Yılmaz, Baran, Nuray; Çalışkan, Melike; Özpala, Ali; Baran, Talat
he rapid development of industrialization and urbanization, along with the increasing human population, has led to serious water pollution. Among water pollutants, organic and inorganic pollutants cause serious problems for both the environment and human health due to their toxicity and carcinogenic properties. One of the best ways to eliminate these pollutants is to develop eco-friendly, efficient, and long-life catalysts. For this purpose, in this study, environmentally friendly microspheres containing sodium alginate (SA), sodium carboxymethyl cellulose (Na-CMC), and gum Arabic (GA) were fabricated as potential stabilizers (SA/Na-CMC/GA). Subsequently, newly heterogeneous catalyst system was designed by immobilizing Pd nanoparticles on them and characterized (Pd@SA/Na-CMC/GA). The catalytic reduction ability of Pd@SA/Na-CMC/GA was then investigated against the reduction of 4-nitroaniline (4-NA), 4-nitrophenol (4-NP), 2-nitroaniline (2-NA), 4-nitro-o-phenylenediamine (4-NPDA), methylene blue (MB), methyl orange (MO), Rodamin B (RhB), potassium hexacyanoferrate(III) (K3[Fe(CN)6]), and hexavalent chromium (Cr(VI)) using NaBH4. The Pd@SA/Na-CMC/GA effectively catalyzed these contaminants in a short period of time under mild reaction conditions. As a result of the performed kinetics studies, rate constants were found to be 0.009 s?1, 0.016 s?1, 0.027 s?1, 0.018 s?1, 0.043 s?1, 0.058 s?1, 0.038 s?1 and 0.041 s?1 for the reduction of 4-NP, 2-NA, 4-NA, 4-NPDA, MO, RhB, K3[Fe(CN)6], and Cr(VI), respectively. Additionally, MO was immediately reduced by Pd@SA/Na-CMC/GA. The microsphere nature of Pd@SA/Na-CMC/GA allowed for easy recovery through simple filtration and successful reuse for up to six cycles.
Corrigendum to “Fabrication of nano-sized Pd catalyst supported on sodium carboxymethyl cellulose/gum Arabic/sodium alginate functionalized microspheres for catalytic reduction of nitro compounds, organic dyes, K3[Fe(CN)6], and chromium(VI) pollutants” [Int. J. Biol. Macromol. 262 (2024) 130134] (S0141813024009371), (10.1016/j.ijbiomac.2024.130134)
(Elsevier B.V., 2024) Baran, Nuray Yılmaz; Çalışkan, Melike; Özpala, Ali; Baran, Talat
The authors regret that the image labelled as ‘b’ in Fig. 12 is incorrect, and the correct version of Fig. 12 is provided below. The authors would like to apologise for any inconvenience caused.
IMAC application of extracellular polymeric substances doped composite membranes for ?-amylase immobilization and kinetic studies
(Elsevier B.V., 2024) Bani, Nurullah; İnanan, Tülden; Acet, Ömür; Odabaşı, Mehmet
Immobilized metal affinity chromatography (IMAC), extensively utilized technique in affinity chromatography, has proven to be highly effective in purifying ?-amylase, a crucial enzyme in industrial applications. Here, Poly (2-hydroxyethyl methacrylate) (PHEMA) based composite membranes were fabricated using the radical copolymerization technique in a petri dish. Extracellular polymeric materials (EPS) as the metal binding agent. The attachment of Cu2+ ions to the membranes occurred through the utilization of EPSs (Cu2+-EPS). The membranes having Cu2+-EPS (Cu2+-EPS-PM) were subjected to various characterization techniques, including scanning electron microscopy (SEM), attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), swelling tests, and surface area measurements. The investigation also encompassed the examination of various factors, including pH, initial ?-amylase concentration, temperature, and ionic strength, that exert an influence on the adsorption of ?-amylase from an aqueous medium. The Cu2+-EPS-PMs demonstrated maximum adsorption capacity with a value of 54.2 mg/g polymer (pH 5.0 sodium acetate buffer, temperature: 25°C, initial ?-amylase concentration of 2 mg/mL). Additionally, it has been observed that the enzyme is able to be used in adsorption and desorption cycles on Cu2+-EPS-PM many times. The investigation also focused on examining the impact of pH, temperature, storage, and operational stability over the activities of both free and immobilized ?-amylase. The outcomes showed that immobilization had positive effects on activity.
Immobilization of Alpha-Amylase onto Ni2+ Attached Carbon Felt: Investigation of Kinetic Parameters from Potato Wastewater
(John Wiley and Sons Inc, 2023) Acet, Ömür; İnanan, Tülden; Koç, Eda Öndül; Sert, Buse; Önal Acet, Burcu; Odabaşı, Mehmet; Ocakoğlu, Kasım; Dizge, Nadir
?-amylase is an important enzyme for textile, food, paper, and the pharmaceutical industrial areas. In this study, Ni2+ attached carbon felt structures with nitrogen active site (Ni2+-N-ACF) are produced. The surface morphologies of the N-ACF and Ni2+-N-ACF are investigated by means of scanning electron microscopy (SEM) analysis. Ni2+ ions binding on the N-ACFs are determined by energy dispersive X-ray (EDX) analysis and a graphite furnace atomic absorption spectrometer (AAS). The effect of pH, ionic strength, initial ?-amylase concentration, and temperature parameters is investigated for ?-amylase immobilization on Ni2+-N-ACF structures. In addition, pH and temperature effect on the activities of the free and the immobilized amylase, kinetic parameters, storage, and operational stabilities are made. Lastly, starch degradation in potato waste water is tested on Ni2+-N-ACF. The obtained results show that ?-amylase immobilized Ni2+-N-ACF can be used for starch degradation on an industrial scale.
Construction and application of MgAl LDH-Schiff base-supported palladium nanocatalyst for Heck reactions and reduction of organic pollutants
(Springer Science and Business Media B.V., 2023) Yılmaz Baran, Nuray; Çalışkan, Melike; Baran, Talat
In this study, a novel nanostructured Pd NPs@MgAl LDH-Schiff base-supported catalyst system was developed through a deposition of Pd NPs on the modified MgAl-layered double hydroxide (MgAl LDH). Structural/morphological features of Pd NPs@MgAl LDH-Schiff base nanocatalyst were investigated by XRD, FESEM, BET, FTIR, EDS, and TEM analyses. It was found that Pd NPs with an average particle size of about 14.50 ± 1.24 nm were successfully produced without agglomeration. The catalytic performance of the prepared Pd NPs@MgAl LDH-Schiff base as a heterogeneous nanocatalyst was subsequently tested in both Heck reaction (HCR) and reductions of 4-nitrophenole (4-NP) and 2-nitroaniline (2-NA). The tests revealed that Pd NPs@MgAl LDH-Schiff base nanocatalyst effectively coupled HCR of styrene and different aryl iodides/bromides by producing reaction yields between 90 and 98% for 3–5 h. In addition, Pd NPs@MgAl LDH-Schiff base nanocatalyst confirmed that it had significant catalytic power by converting 4-NP and 2-NA to 4-aminophenole (4-AP) and 2-phenylenediamine (2-PDA) in 50 s and 45 s, respectively. The rate constants for the reductions of 4-NP and 2-NA in the presence of Pd NPs@MgAl LDH-Schiff base nanocatalyst were determined as 0.017 s?1 and 0.023 s?1, respectively. Due to its heterogeneous nature and the strong synergistic interaction between Pd NPs and prepared MgAl LDH-Schiff base as support, Pd NPs@MgAl LDH-Schiff base nanocatalyst was easily recovered and reapplied for six consecutive runs with unchanged structural/morphological features.
Pd@MgAl LDH/2-ThCA: A sustainable, active and recyclable nanocatalyst system for the rapid and efficient catalytic reduction of organic pollutants
(Elsevier B.V., 2023) Yılmaz Baran, Nuray; Çalışkan, Melike; Baran, Talat
Catalytic reduction of toxic pollutants such as nitroaromatics and organic dyes found in water/wastewater by heterogeneous nano-structured metallic catalysts is a promising method for wastewater treatment. The need for effective and reusable catalyst systems is recently increasing due to the soaring water pollution. For this purpose, in this study, a newly Pd@MgAl LDH/2-ThCA catalyst system was successfully developed by depositing palladium nanoparticles onto a modified MgAl LDH support, characterized and then used to eliminate these contaminants in the presence of NaBH4. Catalytic applications indicated that Pd@MgAl LDH/2-ThCA catalyst efficiently reduced 2-nitroaniline (2-NA), 4-nitrophenole (4-NP), 4-nitroaniline (4-NA), and 4-nitro-o-phenylenediamine (4-NPDA) with rate constants of 0.011 s?1, 0.0075 s?1, 0.017 s?1, and 0.02 s?1, respectively. Additionally, Pd@MgAl LDH/2-ThCA successfully degraded methyl orange (MO) and rhodamine B (RhB) with rate constants of 0.019 s?1 and 0.015 s?1, respectively. Furthermore, it was found that methylene blue (MB) was immediately degraded by Pd@MgAl LDH/2-ThCA. Reusability tests revealed that Pd@MgAl LDH/2-ThCA maintained its activity/stability after the 5 successive cycles, verifying its practical application potential. This paper reveals that Pd@MgAl LDH/2-ThCA is an effective, sustainable, and alternative catalyst system for the treatment of toxic environmental pollutants.
Synthesis of palladium nanoparticles stabilized on Schiff base-modified ZnO particles as a nanoscale catalyst for the phosphine-free Heck coupling reaction and 4-nitrophenol reduction
(Nature Research, 2023) Baran, Nuray Yılmaz; Baran, Talat; Nasrollahzadeh, Mahmoud
Recently, the development of heterogeneous nanocatalytic systems using solid supports has been gaining importance due to some advantages such as easy handling, high thermal stability, high efficiency, reusability, and so on. Therefore, the design of catalyst supports for the preparation of stable heterogeneous catalytic systems is of great importance. In this work, Schiff base-modified ZnO particles have been developed (ZnO–Scb) as a novel support. A heterogeneous nanocatalyst system has then been prepared by immobilizing palladium nanoparticles (Pd NPs) on the ZnO-Scb surface as the support. The resulting palladium nanocatalyst (Pd–ZnO–Scb) structure has been characterized by different analytical techniques (FT-IR, XRD, TEM, FE-SEM, elemental mapping and EDS) and used to catalyze the Heck coupling reactions and 4-nitrophenol (4-NP) reduction. Test results revealed that Pd–ZnO–Scb could effectively couple various aryl halides with styrene in yields of up to 98% in short reaction times. Pd–ZnO–Scb was also efficiently used in the complete 4-NP reduction within 135 s at room temperature. Additionally, it was found that Pd–ZnO–Scb was more effective than other reported catalysts in the Heck coupling reaction. Moreover, the recycling tests indicated that Pd–ZnO–Scb could be easily isolated from the reaction medium and reused in seven consecutive catalytic runs while retaining its nanostructure.
CMC-based edible coating composite films from Brewer's spent grain waste: a novel approach for the fresh strawberry package
(Springer Science and Business Media Deutschland GmbH, 2023) Öztuna Taner, Öznur; Ekici, Lütfiye; Akyüz, Lalehan
This study points to the coated strawberry with new edible films originating from the components of Brewer's spent grain (BSG) obtained as a large amount of waste during brewing. The aim of this study was to measure the high protein, phenolic compounds and cellulose from the BSG waste, which is created as waste in the brewing and mostly used as animal feed, with a new approach to coating strawberries. Cellulose, protein and phenolic compounds were extracted from BSG which is high in these components. Carboxyl methylcellulose (CMC) was synthesized from the obtained cellulose to produce edible films incorporated with different concentrations of protein and phenolic compounds of BSG. The production of the films was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron micrographs (SEM) and mechanical analysis and their antioxidant activities. Weight loss, titration acidity, pH, soluble solids and anthocyanin content were determined for uncoated and coated strawberries with each formulation. Total phenolic was observed to be 2.28 mg GAE/g, and the total protein amount in BSG was observed to be 26.81 g per 100 g dry weight. The results showed that the protein and phenolic compounds used in CMC benefited the CMC film-coated strawberry and could be used as a food packaging material in future. The appearance of composite film-coated strawberry was better than that of uncoated films at the end of the 5 days of storage at room temperature due to the protective properties of the film. Graphical abstract: [Figure not available: see fulltext.]
Anticholinergic, antioxidant, and antibacterial properties of vitex agnus-castus L. seed extract: assessment of Its phenolic content by LC/MS/MS
(John Wiley and Sons Inc, 2022) Kavaz, Arzu; Işık, Mesut; Dikici, Emrah; Yüksel, Mehmet
In this current study, Vitex agnus-castus seed ethanol extracts were analyzed for their phytochemical component content, anticholinergic and antioxidant activities, and antibacterial properties. The phenolic compound composition of these seeds was determined by using LC/MS/MS. Antioxidant activity of the seeds was examined by the DPPH, ABTS, Fe3+–Fe2+ reducing, and CUPRAC. Also, the anticholinergic activity was measured by the inhibition of acetylcholinesterase (AChE). The antibacterial activity was performed by disc diffusion and minimum inhibitory concentration methods. The main phenolic compound was vanillic acid (22812.05 ?g/L) and followed by luteolin, fumaric acid, quercetin, caffeic acid, 4-hydroxybenzoic acid, salicylic acid, kaempferol, butein, ellagic acid, resveratrol, catechin hydrate, phloridzin dehydrate, naringenin, respectively. The DPPH free radical scavenging value of ethanol extract of plant seeds was 9.41 %, while the ABTS radical scavenging activity was determined as 12.66 %. The ethanol extract of the seeds exhibited antibacterial activity on Escherichia coli, Staphylococcus aureus, and Salmonella Typhimurium, differently. S. aureus was found to be more susceptible to the extract than other bacteria. Also, the inhibition effect of seed ethanolic extract on the AChE with IC50 values were 36.34±5.6 ?g/mL. From the results, V. agnus-castus seed can be suggested as a promising natural antioxidant and antibacterial candidate for the preservation of foods.
Kükürt bazlı miksotrofik denitrifikasyon prosesindeAzot/Fosfor (A/F) oranının nitrat giderimine etkisi
(Bitlis Eren Üniversitesi Rektörlüğü, 2022) Öztürk, Arzu
Tüm dünyada olduğu gibi Türkiye’de de tarımsal sulama, yoğun gübreleme, atıksuların uygunsuz deşarjı gibi nedenlerle sularda nitratın arttığı görülmektedir. Sağlığa zararları nedeniyle nitratın giderimi için pek çok arıtma teknolojileri geliştirilmiştir. Bu çalışmada mevcut nitrat giderim yöntemlerine alternatif, etkin ve avantajlı bir yöntem olan miksotrofik denitrifikasyon kullanılmıştır. Bu yöntem ototrofik ve heterotrofik denitrifikasyonun birlikte kullanılması esasına dayanır. Bu nedenle miksotrofik denitrifikasyonu etkileyen elektron verici kaynağı, karbon/azot (K/A) oranı, azot/fosfor (A/F) oranı, sıcaklık, Hidrolik Bekleme Süresi (HBS), pH, alkalinite, girişte verilen organik maddenin cinsi gibi pek çok parametre bulunmaktadır. Bu çalışma ile miksotrofik denitrifikasyonun etkin bir şekilde gerçekleşmesi için gerekli optimum A/F oranının tespit edilmesi amaçlanmıştır. Bu amaçla kurulan laboratuvar ölçekli kolon reaktörlerde elektron vericinin kükürt ve metanol, elektron alıcının nitrat olduğu bir sistem kurulmuştur. Literatür incelenerek 5/1, 5/0.5, 5/0.25, 5/0.1 A/F oranları seçilmiş ve bu oranlarda reaktörler işletilmiştir. İşletme koşullarının belirlenmesinde motivasyon, besine eklenecek fosfat miktarı için optimum miksotrofik koşulları sağlayacak minumum miktarın tespiti olmuştur. Reaktör sıcaklığının 20±5 C0 olduğu koşullarda miksotrofik denitrifikasyonun ÇOK/NO3-N 0.66 oranında gerçekleştiği bulunurken, optimum A/F oranın 5/0.5 olarak bulunmuştur. Böylece hem ÇOK/NO3-N oranı hem de A/F oranı literatürde bildirilen değerlerden daha düşük olduğu halde miksotrofik denitrifikasyonun başarılı bir şekilde gerçekleştiği görülmüştür.
Phenolic profile and antioxidant, anticholinergic, and antibacterial properties of corn tassel
(MDPI, 2022) Al-Khayri, Jameel M.; Yüksel, Arzu Kavaz; Yüksel, Mehmet; Işık, Mesut; Dikici, Emrah
Corn tassel (CT) is a waste part of the corn plant. It is a good co-product and rich in terms of bioactive compounds and phytochemicals. This research tried to show the phenolic profile, antioxidants, anticholinergic activities, and antibacterial properties of CT ethanol extract. The phenolic content analysis of the CT was determined quantitatively by LC-MS/MS, and the antioxidant capacity was measured using ABTS, DPPH, Cu2+-Cu+, and Fe3+-Fe2+ reducing methods. The anticholinergic measurements of CT were detected by inhibition of acetylcholinesterase (AChE). The antibacterial activity was determined by MIC and disc diffusion methods. Many phenolic compounds such as vanillic acid, caffeic acid, fumaric acid, acetohydroxamic acid, butein, myricetin, resveratrol, catechin hydrate, and 4-hydroxybenzoic acid were detected in ethanol extract of CT. The obtained plant ethanol extract had a 7.04% DPPH value, while it showed ABTS activity at 9.45%. Moreover, it had a 0.10 mg/mL inhibition effect on the AChE in terms of IC50 values. The ethanol extract of the CT had an antibacterial property on the investigated bacteria at different ratios. In conclusion, this research aims to consider CT as a source of phenolic compounds and to reveal its bioactive properties and its effects on the treatment of some diseases.
Modified chitosan-zeolite supported Pd nanoparticles: A reusable catalyst for the synthesis of 5-substituted-1H-tetrazoles from aryl halides
(Elsevier B.V., 2022) Sajjadi, Mohaddeseh; Nasrollahzadeh, Mahmoud; Ghafuri, Hossein; Baran, Talat; Baran, Nuray Yılmaz; Orooji, Yasin; Shokouhimehr, Mohammadreza
A novel heterogeneous catalyst has been developed using chitosan-zeolite supported Pd nanoparticles (PdNPs@CS-Zeo) and used in an efficient synthesis of 5-substituted-1H-tetrazoles from aryl halides with high yields for relatively short reaction times with an easy work-up procedure. In this method, highly effective and reusable PdNPs@CS-Zeo catalyst was used in the reaction of various aryl iodides/bromides with K4[Fe(CN)6] as a non-toxic cyanide source to catalyze the [2 + 3] cycloaddition of the corresponding aryl nitriles with NaN3 in the sequential one-pot preparation of 5-substituted-1H-tetrazoles. The synthesized PdNPs@CS-Zeo nanocatalyst was characterized using XRD, FTIR, TEM, HRTEM, XPS, Raman, TG-DTG, ICP-OES, BET, and EDS mapping. Additionally, the nanocatalyst could be effectively separated by filtration and reused for multiple times without significant decrease of catalytic activity.
Cryogel disks for lactase immobilization and lactose-free milk production
(Academic Press, 2022) İnanan, Tülden
This study aims to optimize lactase immobilization onto Fe-chelated cryogel disks. p(AAm-HEMA) cryogel disks were prepared by free radical polymerization and chelated with Fe ions to prepare IMAC material. The lactase immobilization was optimized after characterization by physical analysis. Lactase activity assays were performed with ONPG and lactose substrates. The maximum amount of immobilized lactase was determined as 107.2 ± 4.3 mg/g at 1.5 mg/mL and pH 4.5. The optimum pH of immobilized lactase was determined as pH 5.0, and the immobilized lactase showed notably higher catalytic activity at pH 3.0 compared to free lactase. The optimum temperature of lactase shifted from 50 °C to 60 °C, and the immobilized lactase presented higher activity at 60 °C and 65 °C than the free lactase. Higher thermal activities were achieved for all temperature values after immobilization. The catalytic effectiveness of lactase was not affected, and similar KM values were calculated for lactose. The immobilized lactase lost 29.2% of its initial activity at the end of 70 days, and preserved 64.9% of initial activity after 25-runs. All lactose in milk was hydrolysed by lactase immobilized cryogel disks in 5 h. The lactase immobilized cryogel disks present encouraging opportunities for lactose-free milk preparation in food industry.
Bitki örneklerinden seçici gallik asit ayrılması için gallik asit baskılanmış polimerlerin hazırlanması
(Balıkesir Üniversitesi, 2021) İnanan, Tülden
Bu çalışmada, yaygın olarak kullanılan doğal bir antioksidan olan gallik asidin (GA) moleküler baskılama yöntemi kullanılarak hazırlanan polimerlerle (MIP) bitki örneklerinden seçici ayrılması gerçekleştirilmiştir. Emülsiyon polimerizasyonu ile hazırlanan polimerler çeşitli yöntemlerle karakterize edilmiştir. GA adsorpsiyonunun optimizasyon çalışmaları, pH 3,5 ortamında 25°C’de 1,2 mg GA-MIP kullanılarak 60 dk sürenin GA adsorpsiyonu için en uygun koşullar olduğunu göstermiş ve GA adsorpsiyonu adsorpsiyon kinetikleri ve izotermleri ile incelenmiştir. Çalışılan tüm derişimler için IF değerinin 1’den büyük olması GA-MIP’lerin baskılanmamış polimerlere (GA-NIP) kıyasla daha fazla GA adsorpladığını kanıtlamaktadır. Ayrıca, IF değerinin GA derişimiyle ters orantılı olarak azalması spesifik olmayan etkileşimlerden kaynaklanmaktadır. MIP’lerin seçiciliğini belirlemek amacıyla GA analogları kullanılarak yarışmalı adsorpsiyon çalışmaları yapılmış ve GA ve analoglarının miktarları yüksek performanslı sıvı kromatografisi ile analiz edilmiştir. Tüm bağıl seçicilik katsayılarının 1’den büyük olması GA-MIP’lerin baskılanmamış polimerlere kıyasla GA’yı tüm analoglarından daha fazla adsorpladığını göstermektedir. Yeşil çay, siyah çay ve karanfil örnekleri ile yapılan gerçek örnek çalışmaları sonucunda en etkin GA adsorpsiyonu ve geri alımının karanfil örnekleriyle elde edildiği belirlenmiştir. HPLC kromatogramları incelendiğinde, GA’nın etkin ve seçici olarak MIP’lerden geri alındığı belirlenmiştir.
?-Amylase immobilized composite cryogels: Some studies on kinetic and adsorption factors
(Springer, 2021) Acet, Ömür; İnanan, Tülden; Önal Acet, Burcu; Dikici, Emrah; Odabaşı, Mehmet
Stability of enzymes is a significant factor for their industrial feasibility. ?-Amylase is an important enzyme for some industries, i.e., textile, food, paper, and pharmaceutics. Pumice particles (PPa) are non-toxic, natural, and low-cost alternative adsorbents with high adsorption capacity. In this study, Cu2+ ions were attached to pumice particles (Cu2+-APPa). Then, Cu2+-APPa embedded composite cryogel was synthesized (Cu2+-APPaC) via polymerization of gel-forming agents at minus temperatures. Characterization studies of the Cu2+-APPaC cryogel column were performed by X-ray fluorescence spectrometry (XRF), scanning electron microscopy (SEM), and Brunauer, Emmett, Teller (BET) method. The experiments were carried out in a continuous column system. ?-Amylase was adsorbed onto Cu2+-APPaC cryogel with maximum amount of 858.7 mg/g particles at pH 4.0. Effects of pH and temperature on the activity profiles of the free and the immobilized ?-amylase were investigated, and results indicate that immobilization did not alter the optimum pH and temperature values. kcat value of the immobilized ?-amylase is higher than that of the free ?-amylase while KM value increases by immobilization.
Pumice particle interface: a case study for immunoglobulin G purification
(Springer Science and Business Media Deutschland GmbH, 2020) Alacabey, ,İhsan; Acet, Ömür; Önal, Burcu; Dikici, Emrah; Karakoç, Veyis; Gürbüz, Fatma; Alkan, Hüseyin; Odabaşı, Mehmet
Cryogels with embedded natural adsorbent are new trend of chromatographic media for separation of biomolecules. In this report, experimental determination of immunoglobulin G (IgG) purification by Cu2+-attached pumice particles unified cryogel (Cu2+-PPUC) was performed. For this purpose, after preparation of Cu2+-attached pumice particles, they were unified with 2-hydroxyethyl methacrylate monomers to produce Cu2+-PPUC through polymerization of gel-forming precursors at subzero temperatures. IgG separation experiments were accomplished in a continuous column system. The highest binding capacity (596.8 mg/g) was obtained by working with 0.02 M phosphate buffer at pH 6.0. The chemical analysis of pumice was examined by X-ray fluorescence spectrometer. Scanning electron microscopy was performed to identify the morphology of Cu2+-PPUC. Langmuir adsorption model was best fitted to interaction when compared to Freundlich model. Temkin model was utilized to characterize adsorption, energetically. Purification ability of Cu2+-PPUC for IgG was shown with high selectivity via reducing SDS–PAGE electrophoresis.

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