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2-Morpholinoethyl-substituted N-heterocyclic carbene (NHC) precursors and their silver(I)NHC complexes: synthesis, crystal structure and in vitro anticancer properties
(Springer, 2018) Aktas, Aydin; Kelestemur, Unzile; Gok, Yetkin; Balcioglu, Sevgi; Ates, Burhan; Aygun, Muhittin
In this study, a series of unsymmetrically 2-morpholinoethyl-substituted benzimidazolium salts and their Ag(I)NHC complexes were synthesized. The 1,3-dialkylbenzimidazolium salts (1a-d) were synthesized in dimethylformamide at 80 A degrees C temperature from the N-(2-morpholinoethyl)benzimidazole and alkyl halides. The Ag(I)NHC complexes (2a-d) were synthesized in dichloromethane at room temperature from the benzimidazolium salts and Ag2O. All compounds were characterized by spectroscopic techniques (NMR and FT-IR) and elemental analyses. Also, the salt 1c and complex 2c were characterized by single-crystal X-ray crystallography. Anticancer activities of 2-morpholinoethyl-substituted benzimidazolium salts and Ag(I)NHC complexes were investigated against the MCF-7 breast cancer cell line, and the IC30 and IC50 values of these compounds were found to be in the range of 241-490 and 6-14 A mu M, respectively.
4-Vinylbenzyl and 2-morpholinoethyl substituted ruthenium (II) complexes: Design, synthesis, and biological evaluation
(Elsevier, 2020) Sari, Yakup; Gurses, Canbolat; Celepci, Duygu Barut; Kelestemur, Unzile; Aktas, Aydin; Yuksel, Sengul; Ates, Burhan
Recently, the medical applications of organoruthenium complexes have attention attracted to organometallic chemists and biochemists. In this study, 4-vinylbenzyl and 2-morpholinoethyl substituted (NHC) Ru(II)(eta(6)-p-cymene) complexes were synthesized and in vitro DNA binding, cell cytotoxicity (anticancer activity) and genotoxicity properties were determined in order to understand the biological activities. These complexes have been prepared from the 4-vinylbenzyl and 2-morpholinoethyl substituted Ag(I) NHC complexes via transmetallation method. The characterization of the new (NHC)Ru(II)(eta(6)-p-cymene) complexes was performed by using H-1 NMR, C-13 NMR, FTIR spectroscopy and elemental analysis techniques. Also, molecular structure of complex 1b was obtained with single-crystal X-ray diffraction method. IC50 value of 1b against MCF-7 cell line was determined as 3.61 mu M and for 1b, an oxidation effect was observed in the concentrations higher than 50 mu g/mL. Comet assay unlike sister chromatid exchange (SCE) analysis data showed correlated results with cytotoxicity as well as DNA binding properties of the complexes. (C) 2019 Elsevier B.V. All rights reserved.
Activation of the Mas receptors by AVE0991 and MrgD receptor using alamandine to limit the deleterious effects of Ang II-induced hypertension
(Wiley, 2023) Tanriverdi, Lokman Hekim; Ozhan, Onural; Ulu, Ahmet; Yildiz, Azibe; Ates, Burhan; Vardi, Nigar; Acet, Haci Ahmet
The MrgD receptor agonist, alamandine (ALA) and Mas receptor agonist, AVE0991 have recently been identified as protective components of the renin-angiotensin system. We evaluated the effects of ALA and AVE0991 on cardiovascular function and remodeling in angiotensin (Ang) II-induced hypertension in rats. Sprague Dawley rats were subject to 4-week subcutaneous infusions of Ang II (80 ng/kg/min) or saline after which they were treated with ALA (50 mu g/kg), AVE0991 (576 mu g/kg), or ALA+AVE0991 during the last 2 weeks. Systolic blood pressure (SBP) and heart rate (HR) values were recorded with tail-cuff plethysmography at 1, 15, and 29 days post-treatment. After euthanization, the heart and thoracic aorta were removed for further analysis and vascular responses. SBP significantly increased in the Ang II group when compared to the control group. Furthermore, Ang II also caused an increase in cardiac and aortic cyclophilin-A (CYP-A), monocyte chemoattractant protein-1 (MCP-1), and cardiomyocyte degeneration but produced a decrease in vascular relaxation. HR, matrix metalloproteinase-2 and -9, NADPH oxidase-4, and lysyl oxidase levels were comparable among groups. ALA, AVE0991, and the drug combination produced antihypertensive effects and alleviated vascular responses. The inflammatory and oxidative stress related to cardiac MCP-1 and CYP-A levels decreased in the Ang II+ALA+AVE0991 group. Vascular but not cardiac angiotensin-converting enzyme-2 levels decreased with Ang II administration but were similar to the Ang II+ALA+AVE0991 group. Our experimental data showed the combination of ALA and AVE0991 was found beneficial in Ang II-induced hypertension in rats by reducing SBP, oxidative stress, inflammation, and improving vascular responses.
Aliphatic Polyurethane Films Based on Hexamethylene Diisocyanate and Saccharides for Biocompatible Transparent Coating on Optic Medical Devices
(Wiley-V C H Verlag Gmbh, 2022) Gurses, Canbolat; Karaaslan-Tunc, Merve Goksin; Kelestemur, Unzile; Balcioglu, Sevgi; Gulgen, Selam; Koytepe, Suleyman; Ates, Burhan
Polyurethanes are widely used in daily life, from the textile industry to medical applications. In this study, a biocompatible and transparent coating from polyethylene glycol-based polyurethanes including different type of saccharide (xylose as monosaccharide, sucrose as disaccharide, or starch as polysaccharide) is prepared. Prepared optically transparent polyurethanes are characterized with different instrumental analysis techniques and contact-angle measurements. Thermogravimetric analysis data allow understanding that the synthesized saccharide based polyurethanes are resistant to high temperatures, which means that medical devices can be easily coated with one of the saccharide-based polymers during the manufacturing process. The study results also show that synthesized polyurethane samples having a different kind of saccharides present high biocompatibility and transparency properties via In vitro cytotoxicity analysis and optic transparency tests. For xylose, sucrose, or starch containing polyurethanes, the tranmittance values are 97.72%, 85.20%, and 89.23%, respectively. In addition, scanning electron microscope images show that the samples also have smooth surfaces which can be used for proper coating of medical devices. Consequently, this manuscript addresses synthesis and characterization of the optically transparent polyurethanes based on specific saccharides for biocompatible and transparent surfaces especially in optic medical devices such as colonoscopy applications and laparoscopic detection probes.
Aminoguanidine mitigates apoptosis, testicular seminiferous tubules damage, and oxidative stress in streptozotocin-induced diabetic rats
(Churchill Livingstone, 2015) Orman, Dogan; Vardi, Nigar; Ates, Burhan; Taslidere, Elif; Elbe, Hulya
This study aimed to investigate the effect of aminoguanidine (AG) against testicular damage streptozotocin (STZ) induced diabetes. Thirty two rats were separated into four groups: control, AG, STZ and STZ + AG. In the STZ group, 12.5 +/- 1.3% of tubules were seen as containing sloughed spermatogenic cells into the lumen, 28.7 +/- 1.8% of tubules were atrophic, 46.2 +/- 2.1% of tubules were degenerative and 8.5 +/- 0.9% of tubules contained giant cells. Statistically, the affected tubule number was significantly lower in the STZ + AG group than in the STZ group. Intensely stained caspase-3 cells showed a statistically significant increase in the STZ group, while it decreased in the STZ + AG group. The enzyme activities of catalase (CAT), superoxide dismutase (SOD) and glutathione (GSH) level decreased and the level of malondialdehyde (MDA) and nitric oxide (NO) increased in the STZ group, while AG treated diabetic rats showed an increase of CAT, SOD activity and GSH level and a decrease in MDA and NO levels. This study shows that the oxidative stress, increased NO level and apoptotic cell death play an important role in diabetic rat testicular damage and that AG treatment of diabetic rats results in protection of spermatogenic cells against oxidative stress and apoptotic cell death. (C) 2015 Elsevier Ltd. All rights reserved.
?-Amylase Immobilization on P(HEMA-co-PEGMA) Hydrogels: Preparation, Characterization, and Catalytic Investigation
(Wiley-V C H Verlag Gmbh, 2021) Dogan, Demet; Ulu, Ahmet; Sel, Evren; Koytepe, Suleyman; Ates, Burhan
The aims of this study are to synthesize and characterize poly (2-hydroxyethyl methacrylate-co-poly (ethylene glycol) methacrylate) (P(HEMA-co-PEG500MA)) structures containing polyethylene glycol (PEG) side groups and to investigate their possible use in alpha-amylase immobilization. For this purpose, P(HEMA-co-PEG500MA) copolymer structures are synthesized by using different monomer ratios. P(HEMA-co-PEG500MA) copolymer structures are confirmed by Fourier transform infrared spectroscopy (FTIR), and elemental analysis techniques. In addition, thermal, and morphological properties of the copolymers are investigated by thermal gravimetric analysis/differential scanning calorimetry, and scanning electron microscopy (SEM). Afterward, alpha-amylase from Aspergillus oryzae is immobilized on synthesized copolymer support by using physical interactions. The success of immobilization is elucidated via FTIR, SEM, and energy dispersive X-ray spectroscopy (EDX) methods. In addition, the influences of temperature, pH, storage time, and repeated uses on the activity of free and immobilized alpha-amylase are investigated. According to the outcomes, the immobilized alpha-amylase possesses a better pH and thermal resistance than the free one. Additionally, the immobilized alpha-amylase maintains about 53% of its original activity after eight reuses and it exhibits about 50% relative activity after 28 days of storage. In conclusion, the immobilized alpha-amylase can be utilized as a potential efficient catalyst to produce maltose from the hydrolysis of starch.
Antiapoptotic and antioxidant effects of ?-carotene against methotrexate-induced testicular injury
(Elsevier Science Inc, 2009) Vardi, Nigar; Parlakpinar, Hakan; Ates, Burhan; Cetin, Asli; Otlu, Ali
Objective: To investigate the effect of beta-carotene against testicular injury induced by methotrexate (MTX). Design: Experimental study. Setting: Animal and histology laboratory at Inonu University. Animal(s): Twenty-eight Wistar male rats. Intervention(s): Twenty-eight rats were separated into four groups: control, beta-carotene, MTX, and beta-carotene + MTX. At the end of the treatment, the animals were killed, and tissue samples were examined via histologic and biochemical methods. Main Outcome Measure(s): in each group, 100 tubules were classified as intact, sloughing, atrophic, and degenerated. Caspase-3, a universal effector of apoptosis, was evaluated according to staining in place of coloring as weak, mild, and strong. Result(s): In the MTX group, 58.5 + 3.7% of tubules were sloughing, 10.8 + 2.1% of tubules were atrophic, and 2.0 + 0.6% of tubules were degenerative. In the beta-carotene + MTX group, the affected tubule number was statistically significantly lower than in the MTX group. The distribution of caspase-3 in the MTX group showed a statistically significant increase, but it decreased in the beta-carotene + MTX group. The enzyme activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GP-x) and the level of malondialdehyde (MDA) increased and decreased in parallel. Conclusion(s): Our results indicate that beta-carotene may be useful in decreasing the side effects of chemotherapy, including apoptotic cell death. (Fertil Steril(R) 2009;92:2028-33. (C)2009 by American Society for Reproductive Medicine.)
Anticancer, antioxidant, DFT calculations, and docking studies of some new peptide-indole conjugates
(Acg Publications, 2024) Kucukbay, Hasan; Gonul, Zeynep; Kurucay, Ali; Ates, Burhan; Boulebd, Houssem; Kucukbay, F. Zehra
In this study, the structures of six new peptide-indole derivatives were elucidated through spectroscopic and analytical methods following their synthesis. In addition to their anticancer and antioxidant properties, density functional theory (DFT) calculations and docking studies were conducted for the compounds. According to the obtained results, compounds 1 and 3 were identified as the most active against the MCF-7 cell line, with IC50 values of 8.72 and 5.86 mu g/mL, respectively. Conversely, compounds 4 and 1 were found to be the most active against the A549 cell line, with IC50 values of 15.43 and 16.10 mu g/mL, respectively. When compared to standard antioxidants using both the DPPH and iron reduction power assays, the compounds did not exhibit significant antioxidant activity. The molecular geometry and electronic properties of the synthesized peptide-indole derivatives were investigated through theoretical calculations using the Density Functional Theory (DFT) method. Molecular docking studies were also conducted to investigate the binding modes of the synthesized compounds within the active sites of EGFR enzyme.
Antioxidant properties of different extracts of black mulberry (Morus nigra L.)
(Tubitak Scientific & Technological Research Council Turkey, 2011) Kutlu, Turkan; Durmaz, Gokhan; Ates, Burhan; Yilmaz, Ismet; Cetin, M. Sevket
In vitro antioxidant properties of 3 different extracts of black mulberry (Morus nigra L.) were investigated. Acidified methanol, acidified water, and non-acidified methanol/water solutions were used to prepare extracts. Different solvents caused different protonation on black mulberry anthocyanin structures, which were predicted according to their UV-VIS spectrum. Extracts indicated 2 main peaks at about similar to 280 and similar to 520 nm with different peak areas in their UV-VIS spectrum. The rank of extracts' total phenolic content and reducing power values were both found to be in correlation with their absorbance at similar to 280 nm. Meanwhile the same relationship was observed between DPPH scavenging activity and absorbance values at similar to 520 nm. Acidified extract of black mulberry was higher in beta-carotene prevention and DPPH radical scavenging activity than non-acidified extract. However, non-acidified extract represented a higher reducing power and metal chelating activity, and a higher content of total phenolics.
Antioxidative effect of melationin, ascorbic acid and N-acetylcysteine on caerulein-induced pancreatitis and associated liver injury in rats
(Baishideng Publishing Group Inc, 2006) Esrefoglu, Mukaddes; Gul, Mehmet; Ates, Burhan; Batcioglu, Kadir; Selimoglu, Mukadder Ayse
AIM: To investigate the role of oxidative injury in pancreatitis-induced hepatic damage and the effect of antioxidant agents such as melatonin, ascorbic acid and N-acetyl cysteine on caerulein-incluced pancreatitis and associated liver injury in rats. METHODS: Thirty-eight female Wistar rats were used. Acute pancreatitis (AP) was induced by two i.p. injections of caerulein at 2-h intervals (at a total dose of 100 mu g/kg b.wt). The other two groups received additional melatonin (20 mg/kg b.wt) or an antioxidant mixture containing L(+)-ascorbic acid (14.3 mg/kb.wt.) and N-acetyl cysteine (181 mg/kg b.wt.) i.p. shortly before each injection of caerulein. The rats were sacrificed by decapitation 12 h after the last injection of caerulein. Pancreatic and hepatic oxidative stress markers were evaluated by changes in the amount of lipid peroxides measured as malondialdehyde (MDA) and changes in tissue antioxidant enzyme levels, catalase (CAT) and glutathione peroxidase (GPx). Histopathological examination was performed using scoring systems. RESULTS: The degree of hepatic cell degeneration, intracellular vacuolization, vascular congestion, sinusoidal dilatation and inflammatory infiltration showed a significant difference between caerulein and caerulein + melatonin (P=0.001), and careulein and caerulein+L(+)ascorbic acid +N-acetyl cysteine groups (P=0.002). The degree of aciner cell degeneration, pancreatic edema, intracellular vacuolization and inflammatory infiltration showed a significant difference between caerulein and caerulein+melatonin (P=0.004), and careulein and caerulein+L(+)-ascorbic acid+N-acetyl cysteine groups (P=0.002). Caerulein-induced pancreatic and liver damage was accompanied with a significant increase in tissue MDA levels (P= 0.01, P = 0.003, respectively) whereas a significant decrease in CAT (P=.0.002, P=0.003, respectively) and GPx activities (P=0.002, P=0.03, respectively). Melatonin and L(+)-ascorbic acid+N-acetyl cysteine administration significantly decreased MDA levels in pancreas (P=0.03, P=0.002, respectively) and liver (P=0.007, P=0.01, respectively). Administration of these agents increased pancreatic and hepatic CAT and GPx activities. Melatonin significantly increased pancreatic and hepatic CAT (P=0.002, P=0.001, respectively) and GPx activities (P=0.002, P=0.001). Additionally, L(+)-ascorbic acid+N-acetyl cysteine significantly increased pancreatic GPx (P = 0.002) and hepatic CAT and GPx activities (P= 0.001, P= 0.007, respectively) CONCLUSION: Oxidative injury plays an important role not only in the pathogenesis of AP but also in pancreatitis-induced hepatic damage. Antioxidant agents such as melatonin and ascorbic acid+N-acetyl cysteine, are capable of limiting pancreatic and hepatic damage produced during AP via restoring tissue antioxidant enzyme activities. (c) 2006 The WJG Press. All rights reserved.
Apricot ameliorates alcohol induced testicular damage in rat model
(Pergamon-Elsevier Science Ltd, 2009) Kurus, Meltem; Ugras, Murat; Ates, Burhan; Otlu, Ali
In this study, we intended to determine the possible preventive effects of dietary apricot on oxidative stress due to ethanol usage in rat testes. The animals were divided into six groups as follows: Group 1 was control. Group 2 received ethanol. Group 3 were fed with apricot diet for 3 months. Group 4 were fed with apricot diet for 6 months. Group 5 received ethanol and apricot diet for 3 months. Group 6 were fed apricot diet for 3 months, and then ethanol + apricot diet for 3 months. Following sacrification, the testes were treated for morphological (tubular and germ cell histology, Sertoli and Leydig cell counts) and biochemical (superoxide dismutase, glutathion peroxidase, catalase, malondialdehyde) analyses. In Group 2, severe histopathological changes in seminiferous tubules and germ cells were determined as well as tubular degeneration and atrophy. Sertoli and Leydig cell counts in the interstitial tissue were decreased. Biochemical parameters revealed tissue oxidative stress. Similar alterations existed in Group 5, although to a lesser extent. In Groups 1, 3 and 4, no histopathological alterations were noted. Results of Group 6 were similar to the controls. Apricot rich diet may have a preventive role on histopathological changes caused by alcohol in rat testes.(C) 2009 Elsevier Ltd. Ail rights reserved.
Beneficial effects of apricot-feeding on myocardial ischemia-reperfusion injury in rats
(Pergamon-Elsevier Science Ltd, 2009) Parlakpinar, Hakan; Olmez, Ercument; Acet, Ahmet; Ozturk, Feral; Tasdemir, Seda; Ates, Burhan; Gul, Mehmet
The present study was undertaken to evaluate the cardio-protective potential of apricot-feeding in the ischemia-reperfusion (I/R) model of rats in vivo. Rats were divided into three groups of 12 rats each. Group 1 was fed with a standard rat chow, groups 2 and 3 were fed with a standard rat chow supplemented with 10% or 20% dried apricot during 3 months before the beginning of I/R studies. To produce I/R, the left main coronary artery was occluded for 30 min, followed by 120 min reperfusion, in anesthetized rats. Infarct sizes were found significantly decreased in 10% (55.0 +/- 4.3%) and 20% (57.0 +/- 2.9%) apricot-fed groups compared to control group (68.7 +/- 2.0%). Light and electron microscopic evaluations of hearts also demonstrated similar beneficial effects on I/R injury in apricot-fed both groups. Total phenolic contents, DPPH radical scavenging and ferric-reducing power as in vitro antioxidant capacities of rat chows were significantly increased after supplementation with apricot for each ratio. Cu, Zn Superoxide dismutase (Cu, Zn SOD) and catalase (CAT) activities were increased, and lipid peroxidation was decreased significantly in the hearts of 20% apricot-fed group after I/R. In conclusion, we clearly demonstrated in vivo cardio-protective activity of apricot-feeding related to its antioxidant phenolic contents in rats subjected to myocardial I/R. (C) 2009 Elsevier Ltd. All rights reserved.
Beneficial effects of chlorogenic acid on methotrexate-induced cerebellar Purkinje cell damage in rats
(Elsevier, 2012) Vardi, Nigar; Parlakpinar, Hakan; Ates, Burhan
Several studies have well confirmed the contribution of oxidative stress in the pathogenesis of methotrexate (MTX)-induced damage in the various organs. Many agents have been tested experimentally to reduce or inhibit the oxidative stress. The aim of this study was to determine the possible protective effect of chlorogenic acid (CLG) on MTX-induced cerebellar damage in rats. The rats were randomly divided into three groups as follows: I: control group; II: MIX group; Ill: CLG + MIX group. In the MIX group; malondialdehyde (MDA) content was found to be increased, whereas superoxide dismutase (SOD), catalase (CAT) activities, and glutathione (GSH) content were decreased. On the other hand, CLG markedly attenuated the elevated MDA content and prevented the deleterious effects of MIX on oxidative stress markers. MIX caused severe loss of Purkinje cells and apoptotic cell death in the cerebellum. The CLG administration before MTX treatment significantly reduced Purkinje cell damage and the expression of apoptotic cells. In conclusion, our results demonstrate that chlorogenic acid treatment may protect the impairment of oxidative stress and ameliorate MIX-induced cerebellar damage at biochemical and histological levels. (C) 2011 Elsevier B.V. All rights reserved.
The Beneficial Effects of Pentoxifylline on Caerulein-Induced Acute Pancreatitis in Rats
(Springer, 2009) Gul, Mehmet; Esrefoglu, Mukaddes; Ozturk, Feral; Ates, Burhan; Otlu, Ali
In this study we aimed to investigate the effect of pentoxifylline on caerulein-induced acute pancreatitis (AP) by detecting oxidative stress markers and performing histopathological examination. Twenty-one adult female Sprague-Dawley rats were divided into three groups as follows: control, caerulein, and caerulein + pentoxifylline groups. Pancreatic tissues of rats from all groups were removed for light and electron microscopic examination and determination of oxidative stress markers. Pancreatic oxidative stress markers were evaluated by the measurements of malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and total glutathione (GSH). Serum amylase and lipase levels were determined spectrophotometrically. The pancreatic damage score was significantly increased (P < 0.005) in the caerulein group, whereas it was decreased (P < 0.05) in the caerulein+ with pentoxifylline group. MDA levels, CAT, SOD, GPx, and GSH activities were significantly altered (P < 0.05, P < 0.005) in the caerulein group and indicated increased oxidative stress. Oxidative stress markers were normalized with pentoxifylline administration. Caerulein administration resulted in significant increase (P < 0.05) in amylase and lipase levels; pentoxifylline reduced the levels of these enzymes. Pentoxifylline is potentially capable of limiting pancreatic damage produced during AP by restoring the fine structure of acinar cells and tissue antioxidant enzyme activities. We concluded that pentoxifylline may have beneficial effects in the treatment of caerulein-induced AP.
Biodegradable non-aromatic adhesive polyurethanes based on disaccharides for medical applications
(Elsevier Sci Ltd, 2014) Ates, Burhan; Koytepe, Suleyman; Karaaslan, Merve Goksin; Balcioglu, Sevgi; Gulgen, Selam
This work addresses synthesis, characterization, adhesive properties, protein adsorption and in vitro biodegradation of non-aromatic polyurethanes (NPUs). The following reactants were used in the syntheses of polyurethanes (PUs): non-aromatic 4,4'-Methylenebis(cyclohexyl isocyanate) (MCI), disaccharides (maltose and sucrose) and polyethylene glycol 200 (PEG 200). The NPUs exhibited low glass transition temperature (T-g) and good thermal stability. The dynamic contact angles on NPUs were influenced by the ratios of PEG 200-disaccharide monomer and the hard segment of the NPUs. The highest adhesion strength in whole polyurethanes was found as 307.6 +/- 50.1 kPa for 15% sucrose containing polyurethane. Protein adsorptions of polyurethane films were measured as average 10 pg Bovine Serum Albumin (BSA)/cm(2) and 5 mu g fibrinogen/cm(2) for maltose, and 15 mu g BSA/cm(2) and 5 mu g fibrinogen/cm(2) for sucrose. Biodegradability ratios of NPUs were in the range of 15-35% for 8 weeks depending on the disaccharides containing NPUs. (C) 2013 Elsevier Ltd. All rights reserved.
Biomedical applications of hybrid polymer composite materials
(Woodhead Publ Ltd, 2017) Ates, Burhan; Koytepe, Suleyman; Balcioglu, Sevgi; Ulu, Ahmet; Gurses, Canbolat
[Abstract Not Available]
Biomimetic approach to tunable adhesion of polyurethane adhesives through Fe3+ crosslinking and hydrophobic tween units with balance of adhesion/cohesion forces
(Elsevier Sci Ltd, 2019) Ates, Burhan; Koytepe, Suleyman; Balcioglu, Sevgi; Karaaslan, Merve Goksin; Kelestemur, Unzile; Gulgen, Selam; Ozhan, Onural
Biocompatible adhesives have some limitations such as weak adhesion and low flexibility. To overcome these limitations, we described multiple strategies to provide strong adhesion and high flexibility through Tweens, chlorogenic acid (CLA) and polyethylene glycol (PEG) by reducing excessive interaction between tissue and the adhesive. We synthesized polyurethane-based adhesives using aliphatic 4,4'-methylenebis(cyclohexyl isocyanate) (HMDI), PEG, CLA and Tween units. Hydrophobic side chains in polymer resulted in lower Tg (- 36.95-30.36 degrees C) which indicated more flexibility. The highest adhesion strengths were found as almost 346 kPa for bare polyurethane and 492 kPa for chelated polymer (PU-T40-CLA-15% (5% Tween 40, 15% chlorogenic acid and 80% PEG 200 containing polymer)) with FeCl3. The addition of Tween units provided more stable structure to polymers which proved with in vitro erosion studies. Relatively low erosion values were seen as 5.7, 5.6 and 8.2% in PU-T40-CLA-5% (15% Tween 40, 5% chlorogenic acid and 80% PEG 200 containing polymer), PU-T40-CLA-10% (10% Tween 40, 10% chlorogenic acid and 80% PEG 200 containing polymer), and PU-T40-CLA-15% (5% Tween 40, 15% chlorogenic acid and 80% PEG 200 containing polymer), respectively. In vitro biocompatibility results showed high cell viability in PU-T40-15% as more than 100%. Overall, our findings indicated that these material designs (PU-T-CLAs) provided to overcome the significant challenges of tissue adhesives by improving the flexible character and adhesive strength of the adhesives.
The Carboxylated Multi-walled Carbon Nanotubes/l-Asparaginase Doped Calcium-Alginate Beads: Structural and Biocatalytic Characterization
(Springer, 2020) Ulu, Ahmet; Karaman, Muhammet; Yapici, Fatma; Naz, Mehmet; Sayin, Selin; Saygili, Eyup Ilker; Ates, Burhan
The calcium-alginate/multi-walled carbon nanotube hybrid beads (Ca-ALG/MWCNT-COOH) as a novel kind of matrix were fabricated and characterized in detailed. l-Asparaginase (l-ASNase), which is important chemotherapeutic enzyme-drug in leukemia, was immobilized on the Ca-ALG/MWCNT-COOH hybrid beads. To the best of our knowledge, this is the first study using Ca-ALG/MWCNT-COOH hybrid beads for l-ASNase immobilization. Our characterization investigations displayed that the hybridization between ALG and MWCNT-COOH caused significant changes on the surface morphology and structure. ALG of 0.5% (w/v), CaCl2 of 0.2 M concentration, enzyme of 187.5 U and bead size of 2 mm was found to be best with respect to enzyme loading efficiency. The enzyme was loaded a high yield (97.0%) on these hybrid beads. Remarkably, the tolerance of immobilized enzyme developed towards temperature and pH changes. The maximum activity for the free enzyme was observed at 35 degrees C, pH 7.5, whereas the immobilized enzyme showed maximum activity at 45 degrees C pH 8.5. After immobilization, storage stability of enzyme improved and retained more than 70% of its initial activity after 4 weeks at ~ 30 degrees C as compared with free enzyme which showed only 20% of residual activity. After immobilization, Km value decreased 1.27-fold compared to free counterpart, indicating increased the affinity between the substrate and enzyme. Moreover, immobilized enzyme maintained more than 36% of its original activity even after consecutive 14 reuse. As result, it is worthy of noting that this kind of hybrid materials may become a promising support material for the immobilization of commercial enzymes in areas such as industrial and medical. Graphic
Cellulose acetate encapsulated upconversion nanoparticles - A novel theranostic platform
(Elsevier, 2021) Topel, Seda Demirel; Balcioglu, Sevgi; Ates, Burhan; Asilturk, Meltem; Topel, Onder; Ericson, Marica B.
Luminescent upconversion nanoparticles (UCNPs) are of great interest in a wide range of nanotechnological applications, particularly in the biomedical area like imaging and therapy but their biocompatibility and stability pose major challenges hampering progression towards further pharmaceutical applications. Herein, we present a biocompatible theranostic platform enabling simultaneous diagnosis and drug delivery consisting of UCNPs encapsulated with cellulose acetate (CA), a biocompatible polymer. Luminescence properties of UCNPs in the developed theranostic platform remain stable even after encapsulation. The size of the CA capsules, ranging from micro- to nano-sized particles, can easily be tuned by adjusting the stirring rate during encapsulation. Doxorubicin, a well-known chemotherapeutic drug, onto the CA nanocapsules containing UCNPs (UCNP-CA nanocapsules) was loaded with up to -63 % efficiency and acid-induced release (similar to 47 %) obtained at pH 3.6 and 5.5. It was found that encapsulation decreased toxicity of UCNPs as confirmed in a cellular assay (L-929 and MCF-7 cell lines). Taken together, the developed UCNP-CA nanocapsules serve as a highly interesting novel theranostic platform, combining the biocompatible optical properties of UCNP, with reduced cell toxicity and drug encapsulating properties of CA. The proposed system could be subject for further refinement and exploration.
CHANGES IN TYROSINE HYDROXYLASE ACTIVITY, ADRENOMEDULLIN (ADM) AND TOTAL RNA LEVELS BY TREATMENT OF ORGANOSELENIUM COMPOUNDS IN RAT HYPOTHALAMUS EXPOSED TO 7,12-DIMETHYLBENZANTHRACENE (DMBA)
(Parlar Scientific Publications (P S P), 2010) Ozdemir, Ilknur; Talas, Zeliha Selamoglu; Gok, Yetkin; Ates, Burhan; Yilmaz, Ismet
The effects of synthetic organoselenium compounds (Se I and Se II) on the activity of tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine synthesis as well as adrenomedullin (ADM) and total RNA levels were determined in the hypothalamus of adult rats exposed to DMBA (7,12-dimethylbenz[a]anthracene). DMBA, an organic environmental pollutant, is a polycyclic aromatic hydrocarbon that can induce a range of toxic effects and stress in rats. Selenium is an essential trace element, which interacts with antioxidants, and has anticancer and antihypertensive properties. TH is an aromatic amino acid hydroxylase whose activity is elevated in response to a range of stress inducers. TH activity is normally regulated by negative feedback in catecholamine biosynthesis. ADM is an abundantly present peptide in a broad range of normal tissues including adrenal medulla, lungs, kidneys and brain. Plasma ADM levels are elevated in a number of diseases including essential hyptertension and chronic renal failure. The antioxidant properties of ADM offer protection against organ damage induced by high blood pressure, ischemia and aging. DMBA treatment increased the TH activity and ADM level in the hypothalamus. These increases were found to be inhibited by Se I and Se II treatments. These studies demonstrate that synthetic organoselenium compounds can suppress DMBA-induced stress-related changes in the rat hypothalamus. Therefore, the antioxidant and antihypertensive effects of Se I and Se II may have important effects in the maintainance of homeostasis.

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