Makale Koleksiyonu

Bu koleksiyon için kalıcı URI

https://hdl.handle.net/20.500.12587/18115

Listeleniyor 1 - 20 / 39

Efficient removal of cationic dyes from aqueous solutions using a modified poly(ethylene terephthalate) fibers adsorbent
(TAYLOR & FRANCIS INC, 2020) Unlu, Nuri; Gunay, Kubra; Arslan, Metin
A novel adsorbent was synthesized through functionalization of glycidyl methacrylate-g-poly(ethylene terephthalate) (GMA-g-PET) fibers with iminodiacetic acid (IDA) to give IDA-GMA-g-PET fibers. This adsorbent was then exploited for the removal of Malachite Green (MG) and Rhodamine B (RB) dyes. MG has shown faster adsorption kinetics and equilibrium was attained in 15 mins. and 90 mins. for MG and RB, respectively. IDA-GMA-g-PET fibers showed 100% removal efficiency for MG and RB dyes from the solutions having initial concentrations of 300 mg L(-1)and 200 mg L-1, respectively. Desorption conditions of dyes and reusability of the fibers were also investigated.
Adsorption of Ag(I) ions from wastewaters using poly(2-aminothiazole): kinetic and isotherm studies
(SPRINGER, 2020) Biyikoglu, Mutluhan; Ciftci, Hakan
In this study, 2-aminothiazole, (2AT), was polymerized with benzoyl peroxide in 1,4-dioxane solution, and adsorption efficiencies of poly(2-aminothiazole), P-2AT, for the Ag(I) ions to remove from the aqueous solutions were investigated. Adsorption experiments were studied at different pH, contact time and initial Ag(I) ion concentration in a batch system. The optimal pH for Ag(I) adsorption onto P-2AT was found to be 5.0, and the maximum adsorption capacity was determined to be 336.98 mg/g for 1200 mg/L Ag(I) solution at 90 min. P-2AT adsorbents were followed up by recycling in multiple adsorption cycles. The results showed that adsorbent can be used several times. Ag(I) ion adsorption performance of the P-2AT was investigated in conjunction with Cu(II) and Zn(II) ions. The selectivity series of ions were found as Ag(I) > Cu(II) > Zn(II). According to the experimental data, the adsorption reaction fitted the pseudo-second-degree kinetic model and the Langmuir isotherm equation.
Synthesis and characterization of poly(ethylene terephthalate) fibers grafted with N-(hydroxymethyl) acrylamide by free radical: its application in elimination of Congo red
(SPRINGER, 2020) Arslan, Metin; Gunay, Kubra; Gok, Zehra; Yigitoglu, Mustafa
In this study, firstly, N-(hydroxymethyl) acrylamide (HMAAm) was grafted on poly(ethylene terephthalate) fibers (PET) by utilizing benzoyl peroxide (Bz(2)O(2)) as an initiator. The alteration in graft percentage with the polymerization time, temperature, concentration of initiator and monomers were investigated. For grafting experiments, the optimum temperature, duration for grafting and initiator concentration were found be 85 degrees C, 4 h and 0.008 M, respectively, and the maximum grafting yield was determined to be 25% at these conditions. After grafting, the morphological and chemical changes on the grafted fibers were examined scanning electron microscopy and Fourier-transform infrared spectroscopy. The thermal properties of the obtained PET fibers were examined with differential scanning calorimeter analysis. In addition, the water absorption capacities of the grafted fibers obtained at optimal conditions were investigated and it was found the maximum percentage of water retention reached 56%. Removal of Congo red (CR) with the grafted fibers was performed using a batch process. The effects of different parameters such as pH, grafting yield of HMAAm, adsorption time and CR concentration on the sorption capacity of the grafted fibers were investigated. The optimal pH for adsorption of CR was found to be 2, and the adsorption process reached equilibrium in 4 h. The amount of adsorbed CR molecules increased with the increment in the grafting yield up to 17%, and the graft copolymers adsorbed CR with 5.62 mg/g efficiency when the initial CR concentration was 80 ppm. The PET-g-HMAAm fibers synthesized in this study can be obtained easily and inexpensively, and the constructed fibers could be used to remove ionic substance from aqueous solution.
A disposable gold-cellulose nanofibril platform for SERS mapping
(ROYAL SOC CHEMISTRY, 2020) Tanis, Saliha Nur; İlhan, Hasan; Güven, Burcu; Tayyarcan, Emine Kübra; Çiftçi, Hakan; Saglam, Necdet; Hakki Boyaci, Ismail
In this study, we present a disposable and inexpensive paper-like gold nanoparticle-embedded cellulose nanofibril substrate for the rapid enumeration ofEscherichia coli(E. coli) using surface-enhanced Raman scattering (SERS) mapping. A disposable SERS substrate was simply constructed by mixing CNF and gold chloride solution at 120 degrees C in a water bath. The application of the resulting substrate was carried out by enrichment and SERS detection ofE. coli. To this end, the spherical gold nanoparticle-embedded cellulose nanofibril substrate was used as a scavenger forE. coli. After the target bacteriaE. coliwere separated from the matrixviaoriented antibodies, the sandwich assay procedure was carried out using 5,5-dithiobis-(2-nitrobenzoic acid) (DTNB)-coated Au nanorod particles that acted as SERS mapping probes. The distribution density of DTNB was demonstrated visually using SERS mapping, and the assay was completed in one hour. The correlation between theE. coliand SERS mapping signals was found to be linear within the range of 15 cfu mL(-1)to 1.5 x 10(5)cfu mL(-1). The limit of detection for the SERS mapping assay was determined to be 2 cfu mL(-1). The selectivity of the developed method was examined withMicrococcus luteus(M. luteus),Bacillus subtilis(B. subtilis), andEnterobacter aerogenes(E. aerogenes), which did not produce any significant response. Furthermore, the developed method was evaluated for detectingE. coliin artificially contaminated samples, and the results were compared with those of the plate-counting method.
Synthesis and Crystal Structure Determination of a Dimeric Complex of Dimethylammoniumbis(p-tert-butylcatecholato) borate
(JAPAN SOC ANALYTICAL CHEMISTRY, 2020) Tombul, Mustafa; Biyikoglu, Mutluhan; Bulut, Adnan; Guven, Kutahms; Isilar, Ozer
The structure of a dimeric complex, namely dimethylammoniumbis{(p-tert-butylcatecholato) borate}, was determined by X-ray crystallography. The compound crystallized in a triclinic system, and was characterized to be in the space group P-1, with cell parameters a = 11.929(7)angstrom, b = 16.833(6)angstrom, c = 11.259(11)angstrom, alpha = 93.75(5)degrees, beta = 91.00(7)degrees, gamma = 100.37(4)degrees, Z = 4, and V = 2218(3)angstrom(3). The crystal packing is conducted by intermolecular/intramolecular N-H-O hydrogen bonds. The B atom adopts a distorted tetrahedral geometry with four O atoms of p-tert-butylcatechol ligands.
Application of 4-VP-g-PET fibers and its N-oxide derivative as an adsorbent for removal of cationic dye
(Springer, 2019) Metin, Arslan; Kubra, Gunay
Poly(ethylene terephthalate) fibers (PET) were grafted with 4-vinyl pyridine (4-VP) by a chemical grafting technique, and an N-oxide derivative was synthesized (N-oxide-4-VP-g-PET). The removal of methylene blue (MB) from the aqueous solutions by this material was investigated. The removal and desorption capacities for MB dye were studied under various conditions.4-VP-g-PET fibers exhibited a very low removal rate when compared to the basic dye; however, N-oxide-4-VP-g-PET fibers showed more increased removal results. 2.5% of the MB dyes removal was observed with 4-VP-g-PET fibers, while 100% of MB dyes removal was found with N-oxide-4-VP-g-PET fibers using 10ppm of MB solution. Removal capacity of N-oxide-4-VP-g-PET fibers increased with increasing pH values. The maximum removal capacity of MB dye on the N-oxide-4-VP-g-PET fibers was found to be 35.1mgg(-1) at 250ppm. Results showed that removal capacity of 4-VP-g-PET fibers was significantly improved by N-oxide functionalization. Almost all adsorbed dyes were eluted by acetic acid in methyl alcohol. Ten removal-desorption cycles indicated that the reactive fibers were favorable for use again without the notable change in removal capacity. The information gained from these studies showed that the N-oxide-4-VP-g-PET fibers demonstrated potential as an effective adsorbent for the extremely effective removal of cationic dyes from aqueous media.
Synthesis of modified poly(ethylene terephthalate) fibers with antibacterial properties and their characterization
(Taylor & Francis As, 2019) Arslan, Metin; Gunay, Kubra
Poly(ethylene terephthalate) (PET) fibers were grafted with vinyl monomers by utilizing benzoyl peroxide. Grafted PET fibers were modified in optimized conditions with several functional groups such as amine, chlorine, hydrogen peroxide(,) and triclosan to gain antibacterial feature. The second part of this study comprised examination of the antibacterial features of PET fibers via use of Staphylococcus aureus (ATCC 29213) and Escherichia coli (ATCC 25922) bacteria. Kirby-Bauer test is used to study antibacterial properties. The longest zone diameter for Trc-GMA-g-PET fibers was 56 mm for E. Coli whereas the biggest diameter for S. aureus bacteria was 130 mm with Trc-MMA-g-PET fibers.
Elimination of carcinogenic bromate ions from aqueous environment with 4-vinyl pyridine-g-poly(ethylene terephthalate) fibers
(Springer Heidelberg, 2019) Gunay, Kubra; Arslan, Metin; Bozkaya, Ogun; Aluc, Yasar; Gok, Zehra Gun
In this study, poly(ethylene terephthalate) fibers grafted with 4-vinyl pyridine (PET-g-4VP) was synthesized with using a radical polymerization method and its removal capacity for bromate ions in the aqueous solution was explored. The synthesized graft copolymer was structurally characterized by scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR). The effect of some parameters such as pH, grafting rate, processing time, and ion concentration on bromate removal was examined with batch experiments. The sorptions of bromate onto the PET-g-4VP fibers were both verified with FTIR and X-ray fluorescence analysis (XRF) and the remaining amount of bromate after adsorption process was determined with an ion chromatography (Shimadzu). Moreover, kinetic and isotherm studies were also performed for adsorption of bromate with the grafted fibers. The point of zero charge (pH(pzc)) of the PET-g-4VP fibers was found to be 7.5 and the fibers removed maximum amount of bromate from aqueous solution at pH 3. Equilibrium time of adsorption was determined to be 75 min and the adsorption kinetic was found to be pseudo-second-order model. It was observed that the increase in the amount of grafted 4VP onto the PET fibers increased the bromate removal capacity of the fibers; however, when the grafting yield of 4VP was over 80%, the bromate removal ability of the fibers decreased. The maximum bromate removal capacity of the PET-g-4VP was determined to be 183 mg/g when the initial bromate amount was 800 mg/L, treatment time was 75 min, pH of the solution was 3, and 4VP grafting yield was 80%. When the initial bromate concentration was higher than 800 mg/L, the removal rate of the PET-g-4VP fibers was not changed. In addition, bromate ion adsorption data indicated compliance with the Freundlich isotherm. The adsorbent fibers obtained by this study may be promising candidates for the removal of bromate ions from the aqueous media.
Removing of Congo red from aqueous solution by 2-hydroxyethyl methacrylate-g-poly(ethylene terephthalate) fibers
(Springer, 2019) Gok, Zehra Gun; Gunay, Kubra; Arslan, Metin; Yigitoglu, Mustafa
Grafting of 2-hydroxyethyl methacrylate (HEMA) on poly(ethylene terephthalate) (PET) fibers was carried out via free-radical polymerization technique using benzoyl peroxide as initiator. The obtained copolymers were examined by scanning electron microscope and Fourier-transform infrared spectroscopy analysis, and it was proved that HEMA was successfully grafted onto the PET structure. The synthesized fibrous adsorbents were used to remove Congo red (CR) from aqueous solutions by batch adsorption method. The effects of pH, grafting yield, operation time and dye concentration were studied to find optimal conditions for adsorption of CR by the HEMA-grafted PET (PET-g-HEMA). The obtained results showed that the amounts of adsorbed dye on the PET-g-HEMA lowered with increasing pH. At pH 2, the dye amount adsorbed by the fibers increased with increasing dye concentration up to 70 ppm and grafting yield up to 110%. It was also seen that the adsorption had considerably rapid kinetic and achieved equilibrium within 60 min. The maximum removing abilities of the grafted fibers was found to be 16 mg/g when the beginning concentration of CR was 70 ppm at pH 2. The dye was desorbed from the loaded fibers with 1 M NaOH solution, and it was found that 83% of the adsorbed dye was recovered. The investigations on reusability of the PET-g-HEMA fibers showed that the constructed fibers can be used at least five times without losing adsorption capacities for CR. All these results indicate that the grafting can be used to remove the anionic dyes from the aqueous solution.
Synthesis of amine-functionalized methacrylic acid-g-poly(ethylene terephthalate) fiber and its Congo red removal ability
(Springer, 2018) Arslan, Metin; Gunay, Kubra
The two kinds of amine-type adsorbents were synthesized by reacting hexamethylenediamine (HMDA) and tetraethylenepentamine (TEPA) with methacrylic acid-g-poly(ethylene terephthalate) (MAA-g-PET) fiber for the removal of Congo red (CR) dye from an aqueous solution. The effect of solvents (toluene, ethanol, 2-propanol, and water) on modification of carboxylic acid group of MAA-g-PET fiber to amine groups (HMDA and TEPA) was investigated. Ethanol and 2-propanol provided a higher amination amount of PET fibers for HMDA and TEPA, respectively. The amination amount of PET fibers increased with increasing concentration of amine (vol%) and graft yield. Effect of various parameters such as pH, graft yield, treatment time, and initial dye concentration on the removal amount of CR on chelating fiber was studied. The removal of CR was higher on the TEPA-MAA-g-PET fiber than on HMDA-MAA-g-PET fiber. The effective pH was 3 for adsorption on HMDA-MAA-g-PET fiber and 6 for adsorption on TEPA-MAA-g-PET fiber. The maximum removal capacities of HMDA-MAA-g-PET fiber and TEPA-MAA-g-PET fiber were 11 and 21 mg/g fiber adsorbent for CR. Consequently, the amine-functionalized MAA-g-PET fiber has demonstrated potential as an effective adsorbent for the removal of acidic dyes from aqueous media.
Amperometric glucose sensor based on the glucose oxidase enzyme immobilized on graphite rod electrode modified with Fe3O4-CS-Au magnetic nanoparticles
(Springer Heidelberg, 2018) Onay, Aykut; Dogan, Uzeyir; Ciftci, Hakan; Cetin, Demet; Suludere, Zekiye; Tamer, Ugur
In this report, an amperometric detection method for blood glucose level was developed benefiting from glucose oxidase (GO) enzyme immobilization on nanoparticle modified graphite rod (GR) electrode. Fe3O4-CS-Au magnetic nanoparticles were synthesized, characterized by TEM, UV-Vis, magnetometry, FTIR, and zeta potential measurements and used for the modification of GR electrode. This modified electrode was used for the detection of glucose level amperometrically at 0.6 V. The obtained calibration graph was linear in the range of 5-30mM glucose concentration with a coefficient of determination (R-2) 0.9971. The limit of detection (LOD) and limit of quantification (LOQ) values were calculated as 0.55 and 1.83mM, respectively. The modified GR electrode showed excellent selectivity in the presence of dopamine, ascorbic acid, and uric acid. The applicability of the developed method was examined in real blood samples by comparing the results obtained from commercial glucose sensor. This novel glucose detection method exhibited fast amperometric response, long storage time, and good selectivity.
Multiwalled Carbon Nanotube-Chitosan Scaffold: Cytotoxic, Apoptotic and Necrotic Effects on Chondrocyte Cell Lines
(Bentham Science Publ Ltd, 2017) Ilbasmis-Tamer, Sibel; Ciftci, Hakan; Turk, Mustafa; Degim, Tuncer; Tamer, Ugur
Background: Carbon nanotubes (CNTs) have been considered highly successful and proficient in terms of their mechanical, thermal and electrical functionalization and biocompatibility. In regards to their significant extent in bone regeneration, it has been determined that CNTs hold the capability to endure clinical applications through bone tissue engineering and orthopedic procedures. In the present study, we report on a composite preparation, involving the use of CNT-chitosan as scaffold for bone repair and regeneration. Through the use of water-soluble tetrazolium salt (WST-1) and double staining methods, the cytotoxic, necrotic, and apoptotic effects of chitosan-multiwalled carbon nanotube nanocomposites on the chondrocyte ATTC cell line have been exhibited. Methods: The chitosan-multiwalled carbon nanotube scaffolds were prepared. Chondrocytes differentiation tool (ATCC) cell line was prepared. WST-1 assay for cytotoxicity studies were performed by using chondrocytes cells in 12.5-200 mu L concentration range. The samples of membranes (chitosan-multiwalled carbon nanotube scaffold) were measured at 2 mg/mL and further prepared amongst chitosan-multiwalled carbon nanotube scaffold's which were placed into separate wells. While in the process of incubation, in the four-hour time range, the plates were immediately read in an Elisa microplate Reader. To predict the number of apoptotic and necrotic cells in culture, the technique of double staining with Hoechst dye was performed with PI on the basis of scoring cell nuclei. The mechanical properties such as tensile strength and elongation at break values of the chitosan only and chitosan/CNT scaffolds were evaluated on Texture Analyzer. Results: Based on the results of the WST-1 assay procedure, the amount of cell viability was not significantly affected by nanocomposite concentrations and the lowest mortality rate of cells was obtained at a concentration of 12.5 mu g/mL, whereas the highest mortality rate was obtained at a rate of 200 mu g/mL. In addition, the effects of chitosan-CNT nanocomposites were not found to cytotoxic on chondrocyte cells. The double staining method has been able to determine the apoptotic and necrotic effects of chitosan MWCNT nanocomposites. The apoptotic and necrotic effects of the combined compounds had varied within the concentrations. In a similar manner to the outcome of the control groups, apoptosis was obtained at a percentage of 2.67%. Under a fluorescent inverted microscope, the apoptotic cell nuclei were stained with a stronger blue fluorescence in comparison to non-apoptotic cells, which may have had an effect. We also compared the strain-stress curve measurements results. The results indicated that the mechanical properties of scaffold were not different. Elongation at break values increased by addition of CNT. Conclusion: CNTs as a biomaterial hold the potential to be used for applications in future regenerative medicine. By using the components of chondrocytes (ATTC) cell lines, the cytotoxicity evaluations were made for the chitosan-multiwalled carbon nanotube scaffold. The chitosan-MWCNT nanocomposites do not seem to induce drastic cytotoxicity to the chondrocyte cells.
One step effective removal of Congo Red in chitosan nanoparticles by encapsulation
(Pergamon-Elsevier Science Ltd, 2017) Alver, Erol; Bulut, Mehmet; Metin, Aysegul Ulku; Ciftci, Hakan
Chitosan nanoparticles (CNPs) were prepared with ionotropic gelation between chitosan and tripolyphosphate for the removal of Congo Red. The production of chitosan nanoparticles and the dye removal process was carried out in one-step. The removal efficiency of Congo Red by encapsulation within chitosan from the aqueous solution and its storage stability are examined at different pH values. The influence of some parameters such as the initial dye concentration, pH value of the dye solution, electrolyte concentration, tripolyphosphate concentration, mixing time and speed on the encapsulation is examined. Congo Red removal efficiency and encapsulation capacity of chitosan nanoparticles were determined as above 98% and 5107 mg Congo Red/g chitosan, respectively. (C) 2016 Elsevier B.V. All rights reserved.
Nanoparticle embedded chitosan film for agglomeration free TEM images
(Wiley-Blackwell, 2017) Dogan, Uzeyir; Ciftci, Hakan; Cetin, Demet; Suludere, Zekiye; Tamer, Ugur
Transmission electron microscopy (TEM) is a very useful and commonly used microscopy technique, used especially for the characterization of nanoparticles. However, the identification of the magnetic nanoparticle could be thought problematic in TEM analysis, due to the fact that the magnetic nanoparticles are usually form aggregates on the TEM grid to form bigger particles generating higher stability. This prevents to see exact shape and size of each nanoparticle. In order to overcome this problem, a simple process for the formation of well-dispersed nanoparticles was conducted, by covering chitosan film on the unmodified copper grid, it was said to result in aggregation-free TEM images. It is also important to fix the magnetic nanoparticles on the TEM grids, due to possible contamination of TEM filament which is operated under high vacuum conditions. The chitosan film matrix also helps to protect the TEM filament from contact with magnetic nanoparticles during the imaging process. The proposed procedure offers a quick method to fix the nanoparticles in a conventional copper TEM grid and chitosan matrix prevents agglomeration of nanoparticles, and thus getting TEM images showing well-dispersed individual nanoparticles.
Synthesis and characterization of PET fibers grafted with binary mixture of 2-methylpropenoic acid and acrylonitrile by free radical: its application in removal of cationic dye
(Springer, 2017) Arslan, Metin; Gunay, Kubra
Grafting of binary vinyl monomer mixtures such as 2-methylpropenoic acid (MPA) and acrylonitrile (AN) onto poly (ethylene terephthalate) fibers (PET) was achieved in an aqueous medium with using benzoyl peroxide like free radical initiator. A new reactively fibrous adsorbent was used for removal of dye such as methylene blue (MB) from aqueous media through batch sorption method. Fibers adsorbent was swelled in solution to support the graft and the subsequent polymerization of MPA/AN onto polyester fibers. Optimum conditions for grafting were discovered and reactive fiber were characterized. Variations of graft yield with time, temperature, initiator concentration and monomer mixture ratio were investigated. The optimum initiator concentration was found to be 8 x 10(-3) mol/L. The percentage of grafting rose steadily with the vinyl monomer mixture monomer concentration (50 %). The optimum temperature and polymerization time were found to be 80 A degrees C and 120 min, respectively. The use of AN and MPA monomers together in grafting produce a significant increased in the graft yield. Experimental studies showed that the percentage removal of MB was a great higher on the MPA/AN grafted PET (MPA/AN-g-PET) fibers than on the original PET fibers. The adsorbed quantity of MB improved with pH and basic pH was appropriate for the elimination of MB. MPA/AN-g-PET fibers removed 98 % of cationic dye when initial concentration diverse from 10 to 80 mg L-1 at pH 9.0. Almost all of the adsorbed cationic dye was eluted by ethanoic acid in methanol. Ten removal-desorption cycles indicated that the reactive fibers were favorable for repetitive use without notable change in removal capacity. Consequently, the MPA/AN-g-PET fibers have demonstrated potential as an effective adsorbent for the extremely effective removal of cationic dyes from aqueous media.
Electrochemical determination of Cu(II) ions using glassy carbon electrode modified by some nanomaterials and 3-nitroaniline
(Elsevier Science Bv, 2015) Dedelaite, Lina; Kizilkaya, Selin; Incebay, Hilal; Ciftci, Hakan; Ersoz, Mustafa; Yazicigil, Zafer; Ramanavicius, Arunas
The aim of this research was to investigate the effect of the several nanomaterials in electrochemical determination of Cu(II) ions. For this aim, firstly the deposition of graphene oxide (GO), graphene, magnetite (Fe3O4), gold-chitosan (AuChts) or multilayer carbon nanotubes (MWCNTs) on the glassy carbon (GC) electrode surface was performed. Then the electrochemical modification of electrode by poly-3-nitroaniline (poly-3NA) was performed by 100 potential cycles in the range between +0.9 V and +1.4 V vs. Ag/AgNO3 at the sweep rate of 100 mV/s. For electrochemical reduction of nitro groups present on modified GC electrode surface, potential cycling was performed in 100 mM HCl between -0.1 V and -0.8 V vs. Ag/AgCl/(KClsat.) at the sweep rate of 100 mV/s. Nanomaterial and poly-3NA modified electrodes were applied in the determination of Cu(II) ions by differential pulse voltammetry. It was determined that GC electrodes consecutively modified with MWCNTs, poly-3NA and then by electrochemical reduction of nitro groups were the most sensitive towards Cu(II) ions with detection limit of 0.5 x 10(-9) M. (C) 2015 Elsevier B.V. All rights reserved.
Paper membrane-based SERS platform for the determination of glucose in blood samples
(Springer Heidelberg, 2015) Torul, Hilal; Çiftçi, Hakan; Çetin, Demet; Suludere, Zekiye; Boyacı, İsmail Hakkı; Tamer, Uğur
In this report, we present a paper membrane-based surface-enhanced Raman scattering (SERS) platform for the determination of blood glucose level using a nitrocellulose membrane as substrate paper, and the microfluidic channel was simply constructed by wax-printing method. The rod-shaped gold nanorod particles were modified with 4-mercaptophenylboronic acid (4-MBA) and 1-decanethiol (1-DT) molecules and used as embedded SERS probe for paper-based microfluidics. The SERS measurement area was simply constructed by dropping gold nanoparticles on nitrocellulose membrane, and the blood sample was dropped on the membrane hydrophilic channel. While the blood cells and proteins were held on nitrocellulose membrane, glucose molecules were moved through the channel toward the SERS measurement area. Scanning electron microscopy (SEM) was used to confirm the effective separation of blood matrix, and total analysis is completed in 5 min. In SERS measurements, the intensity of the band at 1070 cm(-1) which is attributed to B-OH vibration decreased depending on the rise in glucose concentration in the blood sample. The glucose concentration was found to be 5.43 +/- 0.51 mM in the reference blood sample by using a calibration equation, and the certified value for glucose was 6.17 +/- 0.11 mM. The recovery of the glucose in the reference blood sample was about 88 %. According to these results, the developed paper-based microfluidic SERS platform has been found to be suitable for use for the detection of glucose in blood samples without any pretreatment procedure. We believe that paper-based microfluidic systems may provide a wide field of usage for paper-based applications.
Electrochemical copper (II) sensor based on chitosan covered gold nanoparticles
(Springer, 2014) Ciftci, Hakan; Tamer, Ugur; Metin, Aysegul U.; Alver, Erol; Kizir, Nevin
This study outlines a new sensing platform based on glassy carbon electrodes modified by gold nanoparticles (AuNPs) for the determination of heavy metal. A glassy carbon electrode was modified by chitosan stabilized AuNPs. AuNPs were prepared by reducing gold salt with a polysaccharide chitosan. Here, chitosan acted as a reducing/stabilizing agent. The AuNPs were characterized with UV-Visible absorption spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. Chitosan covered AuNPs were immobilized on the glassy carbon electrode for the determination of Cu (II) in aqueous solutions. The electrochemical determination of Cu (II) ions was performed using the differential pulse voltammetry technique. Some parameters for Cu (II) determination, such as pH, preconcentration time and electrolysis potential of Cu (II), were optimized. The detection limit was calculated as 5 x 10(-9) mol L-1 by means of the 3:1 current-to-noise ratio. The interference of Cr(III), Fe(II), Ni(II), Pb(II), Mg(II), Zn(II), Ba(II) ions was investigated and showed a negligible effect on the electrode response. Recovery studies were carried out using tap water.
Development of poly(3-aminophenylboronic acid) modified graphite rod electrode suitable for fluoride determination
(Elsevier Science Bv, 2014) Ciftci, Hakan; Oztekin, Yasemin; Tamer, Ugur; Ramanaviciene, Almira; Ramanavicius, Arunas
Poly(3-aminophenylboronic acid), (PAPBA) film was formed on the graphite rod surface by potential cycling. The PAPBA-modified graphite rod (PAPBA/GR) electrode prepared in this way was used for potentiometric fluoride determination. The linear calibration range was from 5 x 10(-4) to 5 x 10(-2) M with the slope of the linear part of the calibration curve of 42.5 mV/log C. No interference effect of the most common ions such as sodium, potassium, chloride, nitrate, iodide, calcium, zinc, aluminum, sulfate and sorbitol was observed during electrochemical determination of fluoride. On the other hand, the PAPBA/GR electrode showed not only good sensitivity and selectivity, but also relatively rapid response to changes of analyte concentrations in the range of 20 s. The sensor was successfully applied for fluoride determination in real sample - toothpaste. (C) 2014 Elsevier B.V. All rights reserved.
High-yield aqueous synthesis of multi-branched iron oxide core-gold shell nanoparticles: SERS substrate for immobilization and magnetic separation of bacteria
(Springer, 2014) Tamer, Ugur; Onay, Aykut; Ciftci, Hakan; Bozkurt, Akif Goktug; Cetin, Demet; Suludere, Zekiye; Greneche, Jean-Marc
The high product yield of multi-branched core-shell Fe3-x O-4@Au magnetic nanoparticles was synthesized used as magnetic separation platform and surface-enhanced Raman scattering (SERS) substrates. The multi-branched magnetic nanoparticles were prepared by a seed-mediated growth approach using magnetic gold nanospheres as the seeds and subsequent reduction of metal salt with ascorbic acid in the presence of a stabilizing agent chitosan biopolymer and silver ions. The anisotropic growth of nanoparticles was observed in the presence of chitosan polymer matrix resulting in multi-branched nanoparticles with a diameter over 100 nm, and silver ions also play a crucial role on the growth of multi-branched nanoparticles. We propose the mechanism of the formation of multi-branched nanoparticles while the properties of nanoparticles embedded in chitosan matrix are discussed. The surface morphology of nanoparticles was characterized with transmission electron microscopy, scanning electron microscopy, ultraviolet visible spectroscopy (UV-Vis), X-ray diffraction, and fourier transform infrared spectroscopy and Fe-57 Mossbauer spectrometry. Additionally, the magnetic properties of the nanoparticles were also examined. We also demonstrated that the synthesized Fe3-x O-4@Au multi-branched nanoparticle is capable of targeted separation of pathogens from matrix and sensing as SERS substrates.

Güncel Gönderiler