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    Adsorption of Ni(II) from aqueous solution by Bacillus subtilis
    (Taylor & Francis Inc, 2012) Bulut, Yasemin; Gul, Ayten; Baysal, Zubeyde; Alkan, Huseyin
    This work reports the application of Bacillus subtilis as adsorbent for the removal of Ni(II) from aqueous solution. Batch experiments were conducted to study the effects of several parameters such as, contact time, initial concentration of adsorbate (25-200 mg L-1), temperature (298-318 K), and adsorbent dose (0.05-0.4 g) on Ni(II) adsorption. Equilibrium adsorption isotherms and kinetics were also investigated. The equilibrium experimental data were analyzed by Freundlich and Langmuir models. The kinetic data obtained with different initial concentration and temperature were analyzed using a pseudo-first-order, pseudo-secondorder, and intraparticle diffusion equations. The results showed that this novel adsorbent had a high adsorption capacity, making it suitable for use in the treatment of Ni(II)-enriched wastewater.
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    Biosorption of Cd+2, Cu+2, and Ni+2 Ions by a Thermophilic Haloalkalitolerant Bacterial Strain (KG9) Immobilized on Amberlite XAD-4
    (Hard, 2015) Alkan, Huseyin; Gul-Guven, Reyhan; Guven, Kemal; Erdogan, Salt; Dogru, Mehmet
    A newly isolated thermophilic haloalkalitolerant bacterial strain (KG9) as immobilized cells on a solid support was presented as a new biosorbent for the enrichment of Cd(II), Cu(II), and Ni(II) prior to flame atomic absorption spectrometric analysis. The KG9 strain was identified as a close member of Bacillus licheniformis following complete sequencing of 16S rRNA. The optimum conditions such as pH, amount of adsorbent, eluent type and volume, flow rate of sample solution, volume of sample solution, and matrix interference effect on the retention of the metal ions were evaluated for the quantitative recovery of the analytes. The analyte ions were quantitatively recovered and desorbed at pH range of 6.0-7.0 and 5 mL of 0.5 mol.L-1 HCl. The loading capacities of adsorbents for Cd(II), Cu(II), and Nip were found to be 22.7, 61.1, and 33.4 mu mol.g(-1) respectively. The analytical detection limits for cadmium(II), copper(II), and nickel(II) were 0.42 mu g.L-1, 0.54 mu g.L-1, and 1.24 mu g.L-1. The proposed procedure was applied for the determination of metal ions in river water, drinking water, and mushrooms. The accuracy of the developed procedure was tested by analyzing NRCC-SLRS4 riverine water and SRM1570a spinach leaves as the certified reference materials.
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    Chemical Profile of Malva Neglecta and Malvella Sherardiana by LC-MS/MS, GC/MS and Their Anticholinesterase, Antimicrobial and Antioxidant Properties With Aflatoxin-Contents
    (Marmara Univ, Fac Pharmacy, 2017) Hasimi, Nesrin; Ertas, Abdulselam; Oral, Elif Varhan; Yener, Ismail; Alkan, Huseyin; Boga, Mehmet; Yilmaz, Mustafa Abdullah
    The purpose of the present work was to determine the phenolic and the fatty acids profiles by LC-MS/MS and GC/MS with their antioxidant, anticholinesterase and antimicrobial activities, and aflatoxin contents of Malva neglecta and Malvella sherardiana. The phenolic contents of M. neglecta and M. sherardiana were determined by LC-MS/MS. Malic and 4-OH benzoic acids were found to be the most abundant compounds in M. neglecta and M. sherardiana, respectively. On the other hand, essential oil and fatty acid compositions were determined by GC/MS analysis. The methanol extracts of the plants showed the highest effect in all antioxidant assays in this study. The methanol extract of M. neglecta showed the highest activity among the petroleum ether, acetone, methanol and water extracts against acetyl-and butyryl-cholinesterase enzymes (53.68% and 63.95% inhibition ratio, respectively). The acetone extracts of M. neglacta and M. sherardiana exhibited moderate activity against C. albicans with 18 and 17 mm inhibion zone diameter, respectively. The results of the present study is also showed that the M. neglecta and M. sherardiana can also be used as a food source due to its high phenolic acid content and good antioxidant property. Also, the samples were aflatoxin free.
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    Molecularly imprinted cryogel as a pH-responsive delivery system for doxorubicin
    (Taylor & Francis Inc, 2017) Cetin, Kemal; Alkan, Huseyin; Bereli, Nilay; Denizli, Adil
    In this study, implantable and degradable molecularly imprinted cryogel was prepared for pH-responsive delivery of doxorubicin. Cryogel discs were synthesized using amino acid-based functional monomer with HEMA and gelatin. The molecularly imprinted discs were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, degradation and swelling tests. In vitro delivery experiments were carried out in order to examine the effects of medium pH and drug content. The degree of degradation of composite cryogels was found to be 83.45 +/- 1.86% after 56days. The release profiles of DOX from molecularly imprinted cryogel discs exhibit a biphasic delivery. It was observed that an initial burst release step from 0 to 12h was followed by a slower and sustained release. Release rate of DOX from cryogel discs increased in more acidic conditions. Kinetic studies showed that a combination of diffusion and erosion control is mainly responsible from the general release behaviors of molecularly imprinted cryogel discs.
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    Phytochemical profile and some biological activities of three Centaurea species from Turkey
    (Pharmacotherapy Group, 2016) Boga, Mehmet; Alkan, Huseyin; Ertas, Abdulselam; Oral, Elif Varhan; Yilmaz, Mustafa A.; Yesil, Yeter; Goren, Ahmet C.
    Purpose: To characterise the phytochemical profile of whole plants of Centaurea balsamita, C. depressa and C. lycopifolia with LC-ESI-MS/MS, and as well as their antioxidant, anticholinesterase and antimicrobial activities. Methods: Organic and aqueous extracts of the three Centaurea species were evaluated for DPPH free radical, ABTS cation radical scavenging and cupric reducing antioxidant capacity (CUPRAC). Acetyl-and butyryl-cholinesterase enzyme inhibition abilities of the extracts using petroleum ether, acetone, methanol and water were studied to determine anticholinesterase activity, while antimicrobial activity was determined by disc diffusion method using appropriate antimicrobial standards and organisms. The phytochemical components of the methanol extracts were assessed by LC-MS/MS. Results: The methanol extract of C. balsamita exhibited much higher DPPH free and ABTS cation radicals scavenging activities (with IC50 of 62.65 +/- 0.97 and 24.21 +/- 0.70 mg/ml, respectively) than the other extracts. The petroleum ether extracts of the plant species exhibited moderate inhibitory activity against butyrylcholinesterase enzymes while the acetone extract of C. balsamita showed good antifungal activity against Candida albicans. Quinic acid (17513 +/- 813 mu g/g, 63874 +/- 3066 mu g/g and 108234 +/- 5195 mu g/g) was the major compound found in the methanol extracts of C. balsamita, C. depressa and C. Lycopifolia, respectively. Conclusion: These results indicate quinic acid is the major compound in the three plant species and that Centaurea balsamita has significant antioxidant, anticholinesterase and antimicrobial properties. Further studies to identify the compounds in the extracts responsible for the activities are required.
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    Poly(Hydroxyethyl methacrylate) immunoaffinity cryogel column for the purification of human immunoglobulin M
    (MDPI Multidisciplinary Digital Publishing Institute, 2020) Bakhshpour, Monireh; Topçu, Aykut Arif; Bereli, Nilay; Alkan, Huseyin; Denizli, Adil
    Human immunoglobulin M (hIgM) antibodies are considered as hopeful tools for diseases therapy. Therefore, chromatography approaches are used to purify hIgM with a single step. In this study, we prepared a poly(hydroxyethyl methacrylate) based immunoaffinity p(HEMA-I) cryogel column by using cyanamide to immobilize antihuman immunoglobulin on the p(HEMA) cryogel for purification of hIgM in aqueous solution and artificial human plasma. The characterization of the p(HEMA) cryogel column was performed by using a scanning electron microscope (SEM), micro-computerized tomography (µ-CT), Fourier transform infrared spectroscopy (FTIR), swelling degree and macro-porosity. Further, the optimizations of various parameters were performed such as, pH, ionic strength, temperature and concentration of hIgM in aqueous solutions. In addition, the Langmuir adsorption model was supported by experimental results. Maximum adsorbed amount of hIgM corresponded to 11.1 mg/g at pH 5.75 [morpholino ethanesulfonic acid (MES buffer)]. Our results indicated that the p(HEMA-I) cryogel column can be reused at least 10 times without significant loss in adsorption capacity. As a natural source, artificial human plasma was selected for hIgM adsorption and the purity of hIgM was evaluated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).
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    Polyphenolic Content, Antioxidant Potential and Antimicrobial Activity of Satureja boissieri
    (Jihad Daneshgahi, 2018) Aras, Abdulmelik; Bursal, Ercan; Alan, Yusuf; Turkan, Fikret; Alkan, Huseyin; Kilic, Omer
    Antioxidant activities of Satureja boissieri extracts were detected by using specific in vitro techniques. Standard antioxidant compounds such as ascorbic acid, BHA (Butylated Hydroxyanisole) and BHT (Butylated Hydroxytoluene) were used to compare with the results obtained from ethanol and water extracts of the plant samples. Both extracts presented high antioxidant actions on ABTS cation radical and DPPH free radical scavenging methods. Furthermore, the antimicrobial activity of S. boissieri was defined by using three fungi species, three Gram-positive and four Gram-negative bacteria species. The reducing power antioxidant activities of samples were measured by CUPRAC and FRAP techniques. Also, phenolic compounds of S. boissieri leaves were identified by UHPLC-ESI-MS/MS. The high concentration of hesperidin (5051 +/- 247 ppb) and rosmarinic acid (4364 +/- 214 ppb) was characterized quantitatively. According to the results, high phenolic content can be thought of as one of the responsible parameters for effective biological activity. Also, its flavonoid and phenolic contents are good natural sources for using in the food industry and pharmacological process.
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    Preparation of poly(hydroxyethyl methacrylate) cryogels containing L-histidine for insulin recognition
    (Elsevier, 2013) Cavus, Aynur; Baysal, Zubeyde; Alkan, Huseyin
    In the present study, affinity adsorption technique was studied for insulin adsorption. Firstly, insulin-imprinted supermacroporous cryogel was prepared for the insulin adsorption. N-methacryloyl-(L)-histidine methyl ester (MAH) was chosen as the monomer. Insulin was complexed with MAH, and insulin-imprinted p(HEMA MAH) [insulin-(MIP)] cryogel was prepared by free radical polymerization with 2-hydroxyethyl methacrylate (HEMA), N,N,N',N'-tetramethylethylenediamine (TEMED) and ammonium persulfate (APS) in an ice bath. Then, insulin was removed from the cryogel by using 0.1 M glycine-HCl buffer (pH: 3.5). The characterization of the cryogel was carried out by using scanning electron microscopy (SEM) and swelling test. The equilibrium swelling ratios of the cryogels were found to be 8.56 +/- 0.42 g H2O/g polymer for p(HEMA) and 7.20 +/- 0.36 g H2O/g polymer for insulin-p(HEMA MAH). Insulin adsorption experiments were performed under different conditions, such as flow rate, medium pH, initial insulin concentration and ionic strength. It was observed that insulin could be repeatedly adsorbed and desorbed with MIP cryogel without any significant decrease in the adsorption capacity. (C) 2013 Elsevier B.V. All rights reserved.
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    Production of lipase by a newly isolated Bacillus coagulans under solid-state fermentation using melon wastes
    (Humana Press Inc, 2007) Alkan, Huseyin; Baysal, Zubeyde; Uyar, Fikret; Dogru, Mehmet
    An extracellular lipase was produced by Bacillus coagulans by solid-state fermentation. Solid waste from melon was used as the basic nutrient source and was supplemented with olive oil. The highest lipase production (78,069 U/g) was achieved after 24 h of cultivation with 1% olive oil enrichment. Enzyme had an optimal activity at 37 degrees C and pH 7.0, and sodium dodecyl sulfate increased lipase activity. NH4NO3 increased enzyme production, whereas organic nitrogen had no effect. The effect of the type of carbon sources on lipolytic enzyme production was also studied. The best results were obtained with starch and maltose (148,932 and 141,629 U/g, respectively), whereas a rather low enzyme activity was found in cultures grown on glucose and galactose (approx 118,769 and 123,622 U/g, respectively). Enzyme was inhibited with Mn+2 and Ni+2 by 68 and 74%, respectively. By contrast, Ca+2 enhanced enzyme production by 5%.
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    Pumice particle interface: a case study for immunoglobulin G purification
    (Springer, 2021) Alacabey, Ihsan; Acet, Omur; Onal, Burcu; Dikici, Emrah; Karakoc, Veyis; Gurbuz, Fatma; Alkan, Huseyin
    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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    Selective removal of the autoantibodies from rheumatoid arthritis patient plasma using protein A carrying affinity cryogels
    (Elsevier, 2010) Alkan, Huseyin; Bereli, Nilay; Baysal, Zubeyde; Denizli, Adil
    Rheumatoid arthritis is a chronic, progressive, deabilitating autoimmune disease that occurs in approximately 1% of adults. Rheumatoid arthritis is characterized by chronic polyarthritis and destruction of multiple joints. In this study, IgM-antibody removal from human plasma with supermacroporous poly(hydroxyethyl methacrylate) [PHEMA] cryogel carrying protein A has been evaluated. The PHEMA cryogel was prepared by bulk polymerization which proceeds in an aqueous solution of monomer frozen inside a plastic syringe (cryo-polymerization). After thawing, the PHEMA cryogel contains a continuous matrix having interconnected macropores of 10-200 mu m size. Pore volume in the PHEMA cryogel was 71.6%. Protein A molecules were covalently immobilized onto the PHEMA cryogel via cyanogen bromide (CNBr) activation. The PHEMA cryogel was contacted with blood in in vitro system for the determination of blood-compatibility. The supermacroporous structure of the PHEMA cryogel makes it possible to process blood cells without blocking the cryogel column. IgM-antibody adsorption capacity decreased significantly with the increase of the plasma flow-rate. The maximum IgM-antibody adsorption amount was 42.7 mg/g. IgM-antibody molecules could be repeatedly adsorbed and eluted without noticeable loss in the IgM-antibody adsorption amount. (C) 2010 Elsevier B.V. All rights reserved.