Browsing by Author "Sahiner, Mehtap"

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Biocompatible and Biodegradable Poly(Tannic Acid) Hydrogel With Antimicrobial and Antioxidant Properties
(Elsevier, 2016) Sahiner, Nurettin; Sagbas, Selin; Sahiner, Mehtap; Silan, Coskun; Aktas, Nahit; Turk, Mustafa
A novel resourceful bulk poly(Tannic Acid) (p(TA)) hydrogel was prepared by crosslinking TA molecules with an epoxy crosslinker, trimethylolpropane triglycidyl ether (TMPGDE), in an autoclave at 90 degrees C for 2 h. The obtained p(TA) hydrogels were in disk form and have highly porous morphology. The swelling characteristics of p(TA) hydrogels were investigated in wound healing pH conditions of pH 5.4, 7.4, and 9 at 37.5 degrees C, and the hydrogels showed good swelling and moisture content behavior. Especially, p(TA) hydrogels were found to be sensitive to pH 9 with 1669% maximum swelling. P(TA) hydrogels were completely degraded at pH 9 hydrolytically in 9 days. Total phenol contents and the effects of scavenging ABTS radicals of degraded p(TA) hydrogels at pH 5.4, 7.4, and 9 were evaluated and calculated in terms of gallic acid equivalent and trolox equivalent antioxidant capacity, respectively, and found to be very effective. Moreover, degraded p(TA) hydrogels display strong antimicrobial behavior against gram positive Staphylococcus aureus, Bacillus subtilis, gram negative Pseudomonas aeruginosa bacteria strains and Candida albicans fungus strain. The WST-1 results indicated that bulk p(TA) hydrogels have no cyctotoxicity to the L929 fibroblast cell line in vitro. (C) 2015 Elsevier B.V. All rights reserved.
Biocompatible Collagen-Synthetic Interpenetrating Polymeric Hydrogels
(Amer Chemical Soc, 2013) Sahiner, Mehtap; Alpaslan, Duygu; Bitlsli, Behzat O.
Collagen-Based Hydrogel Films as Drug-Delivery Devices With Antimicrobial Properties
(Springer, 2014) Sahiner, Mehtap; Alpaslan, Duygu; Bitlisli, Behzat O.
Collagen (coll)-containing hydrogel films were prepared by mixing degraded collagen with monomers such as acrylamide (AAm), and 2-hydroxy ethylmethacrylate (HEMA) before the polymerization/cross-linking of composites as p(coll-co-AAm), and p(coll-co-HEMA), respectively. These materials were used as drug-delivery devices for potential wound dressing materials by loading and releasing of model drugs such as gallic acid (GA) and naproxen (NP). A linear release profile was obtained up to 32-h release from GA-loaded p(coll-co-AAm) interpenetrating polymeric networks films, and 36-h linear release profile of NP for p(coll-co-HEMA). Furthermore, metal nanoparticles such as Ag and Cu prepared within these hydrogel films offered antimicrobial characteristic against known common bacteria such as Escherichia coli, Bacillus subtilis, and Staphylococcus aureus.
Environmental Application of Pei Based Hydrogels in Different Morphology and Sizes: Bulk, Microgel, and Cryogel
(Amer Chemical Soc, 2015) Sahiner, Nurettin; Demirci, Sahin; Sahiner, Mehtap; Al-Lohedan, Hamad; Aktas, Nahit
Fast Removal of High Quantities of Toxic Arsenate Via Cationic P(Aptmacl) Microgels
(Academic Press Ltd- Elsevier Science Ltd, 2016) Rehman, Saif Ur; Siddiq, Mohammed; Al-Lohedan, Hamad; Aktas, Nahit; Sahiner, Mehtap; Demirci, Sahin; Sahiner, Nurettin
Hydrogels are resourceful materials and can be prepared in different morphology, size, surface charge and porosity adopting different polymerization techniques and reaction conditions. The cationic poly(3-acrylamidopropyl)trimethylammonium chloride (p(APTMACl)) microgels were synthesized by photo-initiated inverse suspension polymerization technique. These microgels were utilized as absorbents for the removal of toxic arsenate (As) from different aqueous environments. The experimental parameters affecting absorption efficiency were investigated, and it was demonstrated that these types of microgels are highly efficient in removing arsenate anions from different aqueous environments compared to the previously reported bulk hydrogel, and cryogel of the same material. A removal efficiency of approximately 97.25% was obtained by immersing 0.5 g microgel in 250 ppm 100 mL solution of arsenate anions for 60 min. Both Langmuir and Freundlich adsorption isotherms were applied to adsorption of arsenate anions by p(APTMACl) microgels, and the Langmuir isotherm was a better representation of the adsorption of arsenate with a high value of R-2 (0.9982). Furthermore, mag-p(APTMACl) microgels were synthesized for the adsorption of arsenate anions to provide easy removal of the microgel composite by using an externally applied magnetic field. Furthermore, re-usability of the p(APTMACl) microgels was also investigated for the adsorption of arsenate anions. CD 2015 Elsevier Ltd. All rights reserved.
Hybrid Hydrogel Films With Antimicrobial Properties
(Amer Chemical Soc, 2013) Sahiner, Mehtap; Alpaslan, Duygu; Bitlisli, Behzat O.
Milk Hydrogels as Nutrient Media and Survival Rate Enhancer Under Cryogenic Conditions for Different Microorganisms
(Springer, 2016) Alpaslan, Duygu; Sahiner, Mehtap; Yuceer, Yonca; Akcali, Alper; Aktas, Nahit; Sahiner, Nurettin
Milk-containing hydrogels from 2-hydroxyethylmethacrylate (HEMA) and acrylamide (AAm) as p(HEMA)/whole milk, p(HEMA)/semi-skimmed milk, p(HEMA)/skimmed milk, p(AAm)/whole milk, p(AAm)/semi-skimmed milk, p(AAm)/skimmed milk were synthesized by conventional redox polymerization technique using corresponding monomers and milk as solvents. The aim of this study was to investigate the use of milk-containing hydrogels as a nutritional medium, e.g., up 124 days for enhanced or longer cryostorage media for various microorganisms such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis, and fungi, Aspergillus niger, Aspergillus fumigates, and a yeast Candida albicans. It was shown that milk hydrogels can be used as nutritional media for the growth of these microorganisms, whereas the control hydrogels cannot be used for the same purpose. The survival rates of p(HEMA)/whole milk and p(AAm)/whole milk hydrogels for E. coli after 124 days were found to exceed those of the control p(HEMA) and p(AAm) hydrogels by 109- and 56-fold, respectively. Moreover, the survival rates for S. aureus were calculated to be 42 and 24 times longer than the controls, as the hydrogels containing whole milk were used as storage media in comparison with the bare hydrogels. Furthermore, the cryogenic survival rates of p(HEMA)/whole milk and p(AAM)/whole milk were compared with whole milk and nutrient broth used as a control, and calculated to be 67-, 171-, 35-, and 89-fold greater, respectively, than those of the control samples for E. coli.
Natural P(Ta) Hydrogel and Microgel Networks for Diverse Potential Biomedical Uses
(Amer Chemical Soc, 2015) Sahiner, Nurettin; Sagbas, Selin; Sahiner, Mehtap; Aktas, Nahit
Quantitative Clinical Diagnostic Analysis of Acetone in Human Blood by Hplc: a Metabolomic Search for Acetone as Indicator
(Hindawi Ltd, 2016) Kalkan, Esin Akgul; Sahiner, Mehtap; Cakir, Dilek Ulker; Alpaslan, Duygu; Yilmaz, Selehattin
Using high-performance liquid chromatography (HPLC) and 2,4-dinitrophenylhydrazine (2,4-DNPH) as a derivatizing reagent, an analytical method was developed for the quantitative determination of acetone in human blood. The determination was carried out at 365 nm using an ultraviolet-visible (UV-Vis) diode array detector (DAD). For acetone as its 2,4-dinitrophenylhydrazone derivative, a good separation was achieved with a ThermoAcclaim C-18 column (15 cm x 4.6mm x 3 mu m) at retention time (t(R)) 12.10 min and flowrate of 1mL min(-1) using a (methanol/acetonitrile) water elution gradient. The methodology is simple, rapid, sensitive, and of low cost, exhibits good reproducibility, and allows the analysis of acetone in biological fluids. A calibration curve was obtained for acetone using its standard solutions in acetonitrile. Quantitative analysis of acetone in human blood was successfully carried out using this calibration graph. The applied method was validated in parameters of linearity, limit of detection and quantification, accuracy, and precision. We also present acetone as a useful tool for the HPLC-based metabolomic investigation of endogenous metabolism and quantitative clinical diagnostic analysis.
Removal of Arsenate and Dichromate Ions From Different Aqueous Media by Amine Based P(taea-Co Microgels
(Academic Press Ltd- Elsevier Science Ltd, 2017) Rehman, Saif Ur; Khan, Abdur Rahman; Sahiner, Mehtap; Sengel, Sultan B.; Aktas, Nahit; Siddiq, Muhammad; Sahiner, Nurettin
In this work, microgels based on tris(2-aminoethyl) amine (TAEA) and glycerol diglycidyl ether (GDE) via simple microemulsion polymerization was prepared as p(TAEA-co-GDE) microgels were used as adsorbent for removal of dichromate (Cr (VI)) and arsenate (As (V)) ions from different aqueous environments. The p(TAEA-co-GDE) microgels were demonstrated very efficient adsorption capacity for Cr (VI), and As (V) that are 164.98 mg/g, and 123.64 mg/g from distilled (DI) water, respectively. The effect of the medium pH on the adsorption capacity of p(TAEA-co-GDE) microgels for Cr (VI) and As (V) ions were investigated. The maximum adsorption capacity was obtained at pH 4.0 for both ions with maximum adsorbed amounts of 160.62, and 98.72 mg/g, respectively. In addition, the microgels were also shown moderate adsorption capacity for Cr (VI) and As (V) from other water sources; tap water with 115.18 mg/g and 82.86 mg/g, sea water with 64.24 mg/g and 46.88 mg/g and creek water with 73.52 mg/g and 59.33 mg/g, respectively. Moreover, the increase in adsorbent dose from 0.025 to 0.125 g enhanced % adsorption of Cr (VI) from 54.13 to 98.03, and As (V) from % 26.72-98.70, respectively. For the adsorption process Langmuir and Freundlich adsorption isotherms were applied and found that Langmuir adsorption isotherm with R-2 value of 0.99 for both the metal ions are suitable. Moreover, the experimental adsorption capacities of Cr (VI) and As (V) were found very close to the theoretical values calculated from Langmuir adsorption isotherm. More importantly, the microgels were made magnetic responsive to recover them easily from adsorption medium for reuse studies by applying external magnetic field with little decrease in adsorption capacity. Additionally, reusability of p(TAEA-co-GDE) microgels was also evaluated for adsorption of Cr (VI) and As (V) from DI water. (C) 2017 Elsevier Ltd. All rights reserved.
Removal of As(V), Cr(Iii) and Cr(Vi) From Aqueous Environments by Poly(acrylonitril-Co Ammonium Chloride)-Based Hydrogels
(Academic Press Ltd- Elsevier Science Ltd, 2015) Dudu, Tuba Ersen; Sahiner, Mehtap; Alpaslan, Duygu; Demirci, Sahin; Aktas, Nahit
Cationic poly(Acrylonitril-co-Acrylamidopropyl-trimethyl Ammonium Chloride) (p(AN-co-APTMACl)) hydrogels in bulk were synthesized by using acrylonitrile (AN) and 3-acrylamidopropyl-trimethyl ammonium chloride (APTMACl) as monomers. The prepared hydrogels were exposed to amidoximation reaction to replace hydrophobic nitrile groups with hydrophilic amidoxime groups that have metal ion binding ability. Those replacements were increased the hydrogels absorption capacity for As(V) and Cr(VI). Langmuir and Freundlich isotherms equations were utilized to obtain the best-fitted isotherm model for the absorption of the ions at different metal ion concentrations. The absorption data of As(V) ion were fitted well to Freundlich isotherm while those of Cr(VI) and Cr(III) ions were fitted well to Langmuir isotherm. The maximum absorption of poly(3-acrylamidopropyl-trimethyl ammonium chloride (p(APTMACl)) and amid-p(AN-co-APTMACl) macro gels were 22.39 mg and 21.83 mg for As(V), and 30.65 mg and 18.16 mg for Cr(VI) ion per unit gram dried gel, respectively. Kinetically, the absorption behaviors of Cr(III) and Cr(VI) ions were fitted well to a pseudo 2nd-order kinetic model and those of As(V) ions were fitted well to a pseudo 1st order kinetic model. (C) 2015 Published by Elsevier Ltd.
Synthesis, Characterization and Modification of Gum Arabic Microgels for Hemocompatibility and Antimicrobial Studies
(Elsevier Sci Ltd, 2017) Farooq, Muhammad; Sagbas, Selin; Sahiner, Mehtap; Siddiq, Mohammad; Turk, Mustafa; Aktas, Nahit; Sahiner, Nurettin
Gum Arabic (GA) microgels were successfully prepared via reverse micellization method with high yield (78.5 +/- 5.0%) in 5-100 mu m size range using divinyl sulfone (DVS) as a crosslinker. The GA microgels were degraded hydrolytically 22.8 +/- 3.5% at pH 1 in 20 days, whereas no degradation was observed at pH 7.4 and pH 9 at 37 degrees C. By using diethylenetriamine (DETA), and taurine (TA) as chemical modifying agents, GA microgels were chemically modified as GA-DETA and GA-TA, and the zeta potential values of 5.2 +/- 4.1 and -24.8 +/- 1.3 mV were measured, respectively in comparison to -27.3 +/- 4.2 mV for GA. Moreover, blood compatibility of GA, GA-TA, and GA-DETA microgels was tested via in vitro protein adsorption, % hemolysis ratio, and blood clotting index. All the microgels were hemocompatible with% hemolysis ratio between 0.23 to 2.05, and the GA microgels were found to be highly compatible with a blood clotting index of 81 +/- 40. The biocompatibility of GA, GA-DETA and GA-Taurine microgels against L929 fibroblast cells also revealed 84.4, 89.1, and 67.0% cell viability, respectively, at 25.0 mu g/mL concentration, suggesting great potential in vivo biomedical applications up to this concentration. In addition, 5 and 10 mgImL minimum inhibition concentrations of protonated GA-DETA microgels (GA-DETA-HCl) were determined against E. coli and S. aureus, respectively. (C) 2016 Elsevier Ltd. All rights reserved.
Synthesis, Characterization, and Use of Carbon Microspheres for Removal of Different Dyes From Aqueous Environments
(Springer, 2017) Sahiner, Nurettin; Farooq, Muhammad; Rehman, Saif Ur; Sagbas, Selin; Sahiner, Mehtap; Siddiq, Mohammad; Aktas, Nahit
Herein, we report the synthesis of carbon spheres (CS) using a relatively low-temperature hydrothermal technique using lactose as precursor pre-treated with HCl. The successful synthesis, spherical morphology, porous morphology, and monodispersed nature of CS were confirmed via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Isoelectric point (IEP) was determined as 3.8, and at neutral conditions the prepared carbon particles are negatively charged at - 43 +/- 2.50 mV. Owing to their spherical morphology, almost uniform distribution and negatively charged surface at neutral conditions, the prepared CS were used as adsorbent for the removal of methylene blue (MB) and Geimsa stain (GS) from aqueous environments at pH 7. It was shown that CS has 97% adsorption capability for GS, whereas for methylene MB, the maximum adsorption capacity was 67% for 0.1-g CS from 50-ppm dye solutions in DI water. The adsorption studies revealed that the Langmuir and modified Fruendlich (MFE) adsorption models resulted in considerably high linear correlation coefficient (r(2)) values and the efficient adsorption of positively charged species on CS can be represented better with the MFE model.
Yara Kaplama Malzemesi Olarak Kollajen Esaslı Hidrojel Filmleri
(2018) Erduğan, Hüseyin; Şahiner, Nurettin; Sahiner, Mehtap; Suner, Selin Sağbaş; Turan, Abdullah
Yara kaplama malzemesi olarak kullanılacak kollajen/kitosan (koll/kitosan) vekollajen/kitosan/poli(N-izopropil akrilamid) (koll/kitosan/p(NIPAm)) iç içe geçmiş ağ yapılı(IPN) hidrojelleri gluteraldehit ve poli(etilenglikol)diakrilat çapraz bağlayıcıları kullanılarakfilm şeklinde sentezlenmiştir. Hazırlanan hidrojellerin morfolojik karakterizasyonu optikmikroskop ile yapılmış ve hidrojel yüzeylerinde 1-20 µm boyutunda mikro gözenekleriçerdiği belirlenmiştir. Hidrojellerin yapısal ve termal karakterizasyonu FT-IR spektroskopisive termal gravimetrik analiz (TGA) ölçümleri ile belirlenmiştir. Koll/kitosan vekoll/kitosan/p(NIPAm) IPN hidrojellerinin pH 5,4, 7,4 ve 9,0 da denge şişme kapasiteleribelirlenmiş ve koll/kitosan/p(NIPAm) hidrojeli en yüksek pH 5,4 değerinde % 428±97oranında şiştiği belirlenmiştir. Ayrıca hidrojellerin 25-50 ºC aralığındaki denge şişmedeğerleri ölçülmüş ve koll/kitosan hidrojellerinin yaklaşık % 200 şişme değeri ile neredeysebütün sıcaklıklarda aynı şişme derecesine sahip olduğu gözlemlenirkenkoll/kitosan/p(NIPAm) hidrojelinin 25 ºC sıcaklıkta % 312±14 oranında şişerken, yapısındakisıcaklık duyarlı p(NIPAM) den dolayı 50 ºC ısıtıldığında % 59±2 şişme değeri ile küçüldüğügözlemlenmiştir. Ayrıca, hazırlanan koll/kitosan esaslı IPN hidrojelleri deksametazon sodyumfosfat ilacının salımında kullanılmış ve koll/kitosan hidrojellerinin 114,6±2,9 mg/g ilacı 15saatte salarken koll/kitosan/p(NIPAm) aynı sürede yaklaşık 51,3±1,2 mg/g saldığıgözlemlenmiştir.