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    AFB1 recognition from liver tissue via AFB1 imprinted magnetic nanoparticles
    (Elsevier, 2022) Erdem, Veli Ziya; Basegmez, Hatice Imge Oktay; Pesint, Gozde Baydemir
    Aflatoxins (AFs) are produced mainly by Aspergillus flavus and Aspergillus parasiticus and aflatoxin B1 (AFB1) is one of the most toxic aflatoxins with its carcinogenic property. AFB1 recognition from samples is very important and PHEMA based AFB1 imprinted magnetic nanoparticles (magAFB1-MIPs) were synthesized for the selective AFB1 recognition from liver tissue. The AFB1-MIPs were synthesized in different mole ratios and NIPs were synthesized for control. Characterization studies of magAFB1-MIPs and NIPs were carried out by swelling tests, surface area measurements, scanning electron microscopy and particle size analysis. The surface area was found as 117 m2/g and the size of the nanoparticles were found as 483 nm in diameter. The percentage yield of polymerization was calculated as 98 % and the template (AFB1) removal ratio from the magAFB1-MIPs was calculated as 91 %. The maximum adsorbtion capacities were calculated as 427.57 ng g-1 for magAFB1-MIPs and 44.6 ng g-1 for magNIPs. Selectivity tests showed that magAFB1-MIPs adsorb AFB1 1.74, 4.40, 2.46 times selective than that of AFB2, AFG1 and AFG2 molecules, respectively. AFB1 removal amount from AFB1 spiked liver tissue was satisfactory and recorded as 10.4 ng g-1 and 54.8 ng g-1 for 2 ng g-1 and 10 ng g-1 spiked liver tissue samples, respectively. AFB1 adsorption amount decrease was found negligible for 10 consecutive adsorption-desorption repeats in reusability study.
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    Development of molecularly imprinted nanoparticles for the detection of cardiovascular diseases biomarker Angiotensin II in human serum
    (Wiley, 2025) Arisoy, Piril; Pesint, Gozde Baydemir
    Angiotensin II (Ang II) is a peptide hormone that causes vasoconstriction and an increase in blood pressure. Due to its relationship with cardiovascular diseases, it is an important biomarker in blood serum. In this study, Ang II imprinted nanoparticles were synthesized by miniemulsion polymerization reaction for the determination of Ang II from human serum. Hydroxyethyl methacrylate (HEMA) based Ang II imprinted (Ang II-MIPnp) and non-imprinted nanoparticles (NIPnp) were synthesized, characterized by zeta size analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectrophotometer (FTIR-ATR). The average particle size of the NPs was recorded as 50 nm. Ang II molecules were successfully removed from the Ang II-MIPnp with a 98% success rate using 0.5 M NaCl solution to obtain template-specific cavities. Then, the adsorption studies were achieved. The binding capacity was found as 4500 pg. g(-1) at 700 pg. mL(-1) Ang II concentration. The selectivity studies showed that Ang II-MIPnp can recognize Ang II molecules 2.76 times and 3.23 times selectivity than Ang I and Vsp respectively. Reusability studies shows that the synthesized nanomaterial is reusable.
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    Enhanced invertase binding from baker's yeast via cryogels included boronic acids
    (Springer, 2023) Pesint, Gozde Baydemir; Yungevis, Burcu Eren; Demircelik, Isik Percin
    Invertase, an industrially significant glycoenzyme, was purified from baker's yeast using poly (2-Hydroxyethyl methacrylate) [PHema-Pba] cryogels functionalized with boronic acid. At subzero temperatures, PHema-Pba cryogels were synthesized and characterized using swelling tests, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The surface area of the PHema- Pba cryogels was 14 m(2)/g with a swelling ratio of 88.3% and macroporosity of 72%. The interconnected macropores of PHema-Pba cryogels were shown via scanning electron microscopy. Invertase binding capacity of PHema-Pba cryogel was evaluated by binding studies in different pH, temperature, and interaction time conditions and the maximum Invertase binding of PHema-Pba cryogel was found as 15.2 mg/g. and 23.7 fold Invertase purification was achieved from baker's yeast using PHema-Pba cryogels. The results show that PHema-Pba cryogels have high Invertase binding capacity and may be used as an alternative method for enzyme purification via boronate affinity systems. [GRAPHICS] .
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    Enhanced laccase separation from fermentation medium using cryogel columns
    (Elsevier, 2023) Eren, Burcu; Zenger, Okan; Basegmez, Hatice Imge Oktay; Pesint, Gozde Baydemir
    The laccase enzyme family belongs to the oxidoreductase enzyme class and is one of the most commercially valuable enzymes that catalyzes the oxidation of one electron of a wide range of phenolic compounds. Separation and purification of laccases are crucial for industry since they play an important role in dye decolorization, biodegradation and food processing. Therefore, developing effective, high yielding and cost-effective methods for laccase production is vital. In this study, it was aimed to prepare cryogel columns for laccase purification following the bioproduction of laccase via Aspergillus niger. 2-hydroxyethyl methacrylate based cryogels were synthesized in the presence of 1-vinylimidazole as the affinity ligand and characterized by swelling tests, Bru-nauer-Emmett-Teller surface area measurement and scanning electron microscopy analysis. Surface area and water uptake ratio of cryogel columns were 35 m2/g and 93 %, respectively. The effect of pH, equilibrium laccase concentration, flow rate, interaction time and temperature on laccase adsorption were examined. The purifi-cation factor was calculated as 10.53 under optimum conditions and the enzyme recovery was found to be 86.7 % from fermentation medium. Current study revealed that laccase purification using cryogels following filtration of fermentation medium could be a promising candidate for industrial applications with eliminating the need for complex chromatographic steps.
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    L-proline determination by molecularly imprinted nanoparticles: A potential nanoscale tool for the diagnosis of metabolic disorders
    (Elsevier, 2024) Nergiz, Mustafa; Zenger, Okan; Pesint, Gozde Baydemir
    Detecting and quantifying amino acids is vital in biochemical analyses, especially for diagnosing metabolic disorders. L-proline, among these amino acids, holds significant relevance for various metabolic disorders in living organisms, particularly in humans. hyperprolinemia arises when ineffective breakdown of L-proline occurs due to enzyme deficiencies, leading to its accumulation in the body and underscoring the need for precise monitoring. To address this challenge, molecular imprinting offers a reliable single-step technique for detecting target molecules like proteins, peptides, amino acids, or ions with high selectivity. Moreover, nanoparticles, with significant surface area-to-volume ratios, enable high-level mass transfer and binding kinetics, making them ideal for nano-scale sensitive applications. In this study, 2-hydroxyethyl methacrylate-based molecularly imprinted nanoparticles were synthesized via mini-emulsion polymerization, combining the advantages of molecular imprinting technique and nanoparticles for the specific recognition of L-proline, and were well-characterized by Scanning Electron Microscopy, zeta-sizer particle size analysis, and Fourier Transform Infrared Spectroscopy. Based on zeta-sizer analysis, the estimated diameters of L-proline-imprinted and non-imprinted nanoparticles (Pro-MIPs and NIPs) were determined to be approximately 27.51 nm and 20.66 nm, respectively. The adsorption of L-proline onto nanoparticles from aqueous solutions was investigated in a batch system, and the maximum Lproline adsorption capacity was determined to be 26.58 mg/g for Pro-MIPs and 4.65 mg/g for and NIPs. The selectivity of Pro-MIPs was assessed using Liquid Chromatography-Tandem Mass Spectrometry, even in human serum and in the presence of competing molecules (L-histidine and L-phenylalanine). Additionally, Pro-MIPs maintained their adsorption capacity through up to 10 adsorption-desorption cycles without significant decrease.
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    Molecularly imprinted spongy columns for Angiotensin(II) recognition from human serum
    (Wiley, 2021) Yildirim, Mehtap; Pesint, Gozde Baydemir
    Angiotensin II (AngII), the effector peptide of the renin angiotensin system and has an important role in regulating cardiovascular hemodynamics and structure. AngII is an important biomarker for certain diseases that are associated with cardiovascular disorders, i.e., influenza, SARS-CoV-2, tumors, hypertension, etc. However, AngII presents in blood in very low concentrations and they are not stable due to their reactivity, therefore spontaneous detection of AngII is a big challenge. In this study, AngII-imprinted spongy columns (AngII-misc) synthesized for AngII detection from human serum, and characterized by surface area measurements (BET), swelling tests, scanning electron microscopy (SEM), FTIR studies. AngII binding studies were achieved from aqueous environment and maximum binding capacity was found as 0.667 mg/g. It was calculated that the AngII-miscs recognized AngII 8.27 and 14.25 times more selectively than competitor Angiotensin I and Vasopressin molecules. Newly produced AngII-misc binds 60.5 pg/g AngII from crude human serum selectively. It has a great potential for spontaneous detection of AngII from human serum for direct and critical measurements in serious diseases, that is, heart attacks, SARS-CoV-2, etc.
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    Preparation of molecularly imprinted bilayer cryogel columns for selective protein depletion
    (Elsevier Sci Ltd, 2022) Zenger, Okan; Pesint, Gozde Baydemir
    In this study, bilayer-imprinted cryogels were synthesized for depletion of human serum albumin (HSA) from human serum. For this purpose, a monolayer HSA-imprinted cryogel with 8% monomer concentration was synthesized and second imprinting process was performed using a polymeric solution with 16% monomer concentration in presence of HSA, in the supermacroporous structure of first layer. Thereby, bilayer HSAimprinted cryogel column (HSA-BLIP) with enhanced surface area was obtained. Bilayer non-imprinted polymer (BL-NIP) and monolayer HSA-imprinted polymers with monomer concentrations of 8% and 16% (HSAMIP(8%) and HSA-MIP16%, respectively) were synthesized as the control group. Synthesized columns were characterized by swelling tests, scanning electron microscopy (SEM), multipoint Brunauer-Emmett-Teller (BET) surface area measurement and micro computed tomography (Micro-CT) analysis. Surface areas of HSA-BLIP, BL NIP, HSA-MIP8% and HSA-MIP(16% )were found to be 39 m(2)/g, 37 m(2)/g, 21 m(2)/g and 12 m(2)/g, respectively. Maximum HSA adsorption was calculated as 106.8 mg/g for HSA-BLIP and 5.14 mg/g for BL-NIP. Selectivity studies were conducted in presence of competitor molecules, human hemoglobin (Hb) and immunoglobulin G (IgG). Finally, selective depletion of HSA directly from human serum was studied. In addition, it was demonstrated that HSA-BLIPs can be used up to 10 times without significant decrease in selective adsorption capacity.
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    Spongy membranes for peroxidase purification from Brassica oleracea roots
    (Elsevier Sci Ltd, 2021) Pesint, Gozde Baydemir; Zenger, Okan; Percin, Isik; Denizli, Adil
    In this work, it was aimed to purify peroxidase from Brassica oleracea roots using newly synthesized cryogel membranes. 2-4-vinylphenylboronic acid (VPBA) containing 2-hydroxyethyl methacrylate (HEMA) [PHE-MABA] cryogel membranes were prepared successfully and swelling tests, scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, contact angle measurements, and Brauner-Emmet-Teller (BET) surface area analysis were done for characterization. Effect of experimental conditions on peroxidase binding capacity of PHEMABA cryogel membranes was determined by examining parameters such as pH, temperature and time with binding studies. Maximum peroxidase binding capacity of PHEMABA cryogel membranes was determined as 22.01 mg/g for 2 mg/mL equilibrium peroxidase concentration at pH 8.0. Finally, peroxidase was purified from Brassica oleracea roots with 85.38% yield and 18.38 purification fold. According to obtained re-sults, spongy PHEMABA cryogel membranes show high peroxidase binding capacity and could be suggested as a boronate affinity model system for enzyme purification.
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    Tannic acid purification from pomegranate peel via tannic acid imprinted particle-embedded cryogel column
    (Elsevier, 2023) Pesint, Gozde Baydemir; Cemek, Kardelen; Zenger, Okan; Anar, Baris Can; Basegmez, Hatice Imge Oktay
    Tannic acid (TA) is hydrolysable tannin found in the leaves and bark of many herbaceous and woody plants. Purification of TA is important due to its antibacterial, antihistaminic, antioxidant, antimutagenic and antitussive properties. In this study, 2-hydroxyethyl methacrylate-based TA-imprinted particle embedded cryogel (TA-MIP) was synthesized to purify TA from pomegranate peel. Furthermore, non-imprinted particle embedded cryogel (NIP) was synthesized to determine specific adsorption properties of TA-MIP, and control cryogel was synthesized without embedding procedure. The synthesized cryogel columns were characterized via scanning electron microscopy, Brunauer-Emmett-Teller surface area analysis, fourier-transform infrared spectroscopy, and swelling studies. Particle-embedding procedure resulted in a significantly higher specific surface area of particle-embedded columns (TA-MIP and NIP, 29 m(2)/g and 25 m(2)/g, respectively) than the specific surface area of control cryogel (9 m(2)/g). Adsorption studies were performed from aqueous solutions and maximum TA adsorption was found to be 34.4 mg/g for TA-MIP, 3.9 mg/g for NIP, and 2.8 mg/g for control cryogel. Within the scope of selectivity study, it was demonstrated that the synthesized columns have a high selectivity for TA against gallic acid (GA) and quercetin (QCT). Finally, purification of TA directly from pomegranate peel extract was studied and results were confirmed by HPLC. Furthermore, it has been proven that TA-MIP cryogel columns can be repeatedly used up to ten-times without any remarkable reduction in the TA adsorption amount.