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https://hdl.handle.net/20.500.12587/18871

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Unprecedented Formation of Potassium Borate Based Carbonate from Chloral Hydrate, Potassium Carbonate and Boric Acid
(Japan Soc Analytical Chemistry, 2021) Tombul, Mustafa; Türkmenoğlu, Elmas; Şahin, Onur
The structure of the reaction product of boric acid, chloral hydrate, and potassium carbonate in H2O, potassium bis(carbonato)borate hydrate K[B(CO2-mu-O-CO2)(2)]center dot 2H(2)O, was determined by X-ray crystallography. The compound crystallized in the orthorhombic system, and was characterized to be in the space group Aba2, with cell parameters of a = 11.0579(10)angstrom, b = 11.1695(10)A, c = 9.0504(9)angstrom, Z = 4, and V = 1117.83(18)angstrom(3). In the crystal structure, intermolecular O-H center dot center dot center dot O hydrogen bonds link the molecules into a supramolecular structure, in which they may be effective in stabilizing the structure. The B atom espouses a distorted tetrahedral geometry with four O atoms of carbonate ligands.
The screening of the safety profile of polymeric based amoxicillin nanoparticles in various test systems
(Elsevier Ireland Ltd, 2021) Guncum, Enes; Bakırel, Tülay; Anlas, Ceren; Işıklan, Nuran; Alkan, Fulya Üstün; Charehsaz, Mohammad; Aydın, Ahmet
Nanotechnology-based drugs show superiority over conventional medicines because of increased bioavailability, lower accumulation in non-target tissues, and improved therapeutic index with increased accumulation at target sites. However, it is important to be aware of possible problems related to the toxicity of these products, which have therapeutically superior properties. Accordingly, the present study was designed to investigate the safety profile of amoxicillin nanoparticles (AmxNPs) that we developed to increase the oral bioavailability of amoxicillin (Amx) in poultry. In the first part of the study, the genotoxicity potential of AmxNPs was evaluated using the Ames test and the in vitro comet assay. The results of Ames test showed that none of the tested concentrations of Amx and AmxNPs cause a significant increase in the revertant number of Salmonella typhimurium strains TA98, and TA100, either with or without metabolic activation. Similarly, the comet assay revealed that AmxNPs did not induce DNA damage at any of the concentrations used, whereas high-dose (200 mu g/mL) of Amx caused a significant increase in the percentage of DNA in the tail. In the second part of the study, the toxicity potential of AmxNPs on broilers was investigated by measuring biochemical parameters. In vivo results demonstrated that AmxNps did not cause a significant change in biochemical parameters, whereas Amx increased ALT, glucose, and cholesterol levels at certain sampling times. The obtained findings suggest that AmxNPs could be a safe promising potential drug in drug delivery systems. (C) 2021 Elsevier B.V. All rights reserved.
The dye adsorption and antibacterial properties of composite polyacrylamide cryogels modified with ZnO
(Elsevier Science Inc, 2021) İnal, Murat; Erduran, Nuran; Gökgöz, Murat
The present study aimed to modify the surface of polyacrylamide cryogels (PAC) with ZnO nanorods (ZNR) to provide them with antibacterial properties. The synthesized ZNR-modified composite PAC (ZMC) characterized by AAS, FTIR, SEM, XRD, XPS, BET surface analysis and TGA studies. A study of the adsorption of Orange G (OG) and antibacterial effect was performed on the synthesized ZMC. The highest adsorption capacity was determined to be at a dye concentration of 142.79 mg/g at 400 ppm, and a pH of 2. From the data obtained, it was found that adsorption fitted the pseudo-second-order kinetic model and Freundlich isotherm. Modified cryogels could be desorbed in a very short time-such as 30 min-and reused approximately twenty times with 80% efficiency. While ZMC cryogels did not show antibacterial activity in the dark, inhibition percentages were determined as 99.79 +/- 3.94% and 99.81 +/- 1.76%, at 1.78 mg/mL cryogel application, MIC90 values were determined as 1.589 +/- 0.063 and 0.660 +/- 0.028 mg/ mL for Escherichia coli, and Staphylococcus aureus, respectively under visible light. The results showed that the composite cryogels obtained had a very high potential to be applied both in the removal of dyes from wastewater and in the purification of microorganism-contaminated water. (c) 2021 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.
Synthesis and drug delivery performance of gelatin-decorated magnetic graphene oxide nanoplatform
(Elsevier, 2021) Işıklan, Nuran; Hussien, Nizamudin Awel; Türk, Mustafa
In the present study, we have designed and developed gelatin-decorated magnetic graphene oxide nanoplatform (MGO@GEL) for photothermal therapy and paclitaxel delivery. The surface morphology, chemical structure, magnetic property, and thermal stability of the MGO@GEL nanosheets were investigated using TEM, AFM, FTIR, XRD, BET, VSM, and TGA methods. Paclitaxel (PAC) as a chemotherapy drug, release behavior was performed at two pH levels and showed strong pH dependence. The anticancer efficiency and biocompatibility of the nanosheets were achieved by MTT analysis using MCF-7 cancer cells with and without 808 NIR laser and L-929 fibroblast cells. Furthermore, the pH-sensitive release behavior of the nanosheets demonstrated higher PAC release at pH 5.5 than at pH 7.4. Moreover, cytotoxicity analysis illustrated the MGO@GEL nanosheets are biocompatible while MGO@GEL@PAC nanosheets exhibited high toxicity to kill MCF-7 cells, especially with NIR laser. Based on the obtained results, the developed multifunctional nanostructures may be a promising candidate for chemo-photothermal therapy and drug delivery.
Spectral analysis and biological activity assessment of silver doped hydroxyapatite
(Taylor & Francis Ltd, 2021) Erdem, Ümit; Bozer, Büşra Moran; Turkoz, Mustafa B.; Metin, Ayşegül Ülkü; Yıldırım, Gürcan; Türk, Mustafa; Nezir, Saffet
In this study, the hydroxyapatite biomaterials are produced by the precipitation method and the role of silver doping within the different molar ratios of 2.0, 5.0, and 10.0% are investigated with some fundamental analysis, including powder XRD, SEM, EDS, FTIR, Raman, and material densities. In vitro biocompatibility assessment is conducted with cytotoxicity and agar diffusion tests. Moreover, genotoxicity tests determine whether the biomaterials produced cause the mutations or not. In addition, a hemolytic effect test examines the variation of hemolytic behavior of compounds. Also, the cell migration experiments inspect the influence of silver ion levels in biomaterials on many biological processes. The experimental results reveal that the honeycomb-patterned morphological structures are obtained for all the products. FTIR and Raman analyses reveal that the dramatic changes in the characteristic functional group peaks are obtained with the increment in the amount of silver ions. The experimental parts related to the biocompatibility assessment of the study show that there seems to be deterioration in biocompatibility as the silver ion-doping level increases in the system. To sum up, the ideal doping value for bone tissue engineering applications is found to be 2%.
Resorbable membrane design: In vitro characterization of silver doped-hydroxyapatite-reinforced XG/PEI semi-IPN composite
(Elsevier, 2023) Doğan, Deniz; Erdem, Ümit; Bozer, Büşra M.; Turkoz, Mustafa Burak; Yıldırım, Gürcan; Metin, Ayşegül Ülkü
In this study, the production and characterization of silver-doped hydroxyapatite (AgHA) reinforced Xanthan gum (XG) and Polyethyleneimine (PEI) reinforced semi-interpenetrating polymer network (IPN) biocomposite, known to be used as bone cover material for therapeutic purposes in bone tissue, were performed. XG/PEI IPN films containing 2AgHA nanoparticles were produced by simultaneous condensation and ionic gelation. Characteristics of 2AgHA-XG/PEI nanocomposite film were evaluated by structural, morphological (SEM, XRD, FT-IR, TGA, TM, and Raman) and biological activity analysis (degradation, MTT, genotoxicity, and antimicrobial activity) techniques. In the physicochemical characterization, it was determined that 2AgHA nanoparticles were homogeneously dispersed in the XG/PEI-IPN membrane at high concentration and the thermal and mechanical stability of the formed film were high. The nanocomposites showed high antibacterial activity against Acinetobacter Baumannii (A.Baumannii), Staphylococcus aureus (S.aureus), and Streptococcus mutans (S.mutans). L929 exhibited good biocompatibility for fibroblast cells and was determined to support the formation of MCC cells. It was shown that a resorbable 2AgHA-XG/PEI composite material was obtained with a high degradation rate and 64% loss of mass at the end of the 7th day. Physico-chemically developed biocompatible and biodegradable XG-2AgHA/PEI nanocomposite semi-IPN films possessed an important potential for the treatment of defects in bone tissue as an easily applicable bone cover. Besides, it was noted that 2AgHA-XG/PEI biocomposite could increase cell viability, especially in dental-bone treatments for coating, filling, and occlusion.
Recovery Studies on RDX from Decommissioned Munitions
(Gazi Univ, 2024) Altın, Soner; Köse, Özge; Metin, Ayşegül Ülkü; Türker, Mehmet
Munitions become obsolete due to the expiration of their shelf life, storage, or inappropriate conditions during use. In this study, it was aimed to recover and purify RDX from waste Composition-B (Comp-B) explosive, which is a mixture of 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), which is the most commonly used as the main fusing agent in military munitions. Waste Comp-B samples were obtained from the munition in two different ways, and different RDX recovery percentages and purity were achieved. Comp-B was obtained both mechanically directly from the ammunition and through the recycling process by melting the main filling of the ammunition with hot water and steam method. TNT was removed from the samples obtained by both methods by utilizing the solubility differences of TNT and RDX in Toluene and RDX was obtained (rRDX). The recovery efficiency was 94% for Comp-B obtained by the mechanical method and 77% for the hot water/steam melting method. As a result of the subsequent purification process, RDX purity for both methods was calculated and determined to be more than 99%.
Preparation, characterization, and evaluation of antibacterial and cytotoxic activity of chitosan-polyethylene glycol nanoparticles loaded with amoxicillin as a novel drug delivery system
(Taylor & Francis Ltd, 2023) Güncüm, Enes; Işıklan, Nuran; Anlas, Ceren; Bulut, Elif; Bakırel, Tülay
In this study, nanoparticles of amoxicillin (AMX) were prepared using chitosan (CHI) and polyethylene glycol (PEG). The physicochemical properties of the particles were investigated by FT-IR, DSC, SEM, and zeta potential analyses. The nanoparticles showed a spherical shape, and the average size of formulations was within the range of 696.20 +/- 24.86 - 359.53 +/- 7.41 nm. Zeta potential data demonstrated that the formulations had positive surface charges with a zeta potential range of 21.38 +/- 2.28 - 7.73 +/- 1.66 mV. FTIR analysis showed that the drug was successfully entrapped in the nanoparticles. DSC results suggested that the drug was present in amorphous form in the polymer matrix. In vitro release studies demonstrated that the release pattern consisted of two phases, with an initial burst release followed by a controlled and sustained release. The MTT assay results on mouse fibroblast cell line indicated that the prepared formulations did not affect the viability of the cells. In the in vitro antibacterial activity test, it was found that the drug-loaded nanoparticles have AMX-equivalent antibacterial activity against E. coli, and S. aureus. These findings revealed that the obtained nanoparticles might be a promising and safe nanocarrier system for efficient delivery of AMX.
Preconcentration and electroanalysis of copper at glassy carbon electrode modified with poly(2-aminothiazole)
(Gazi Univ, 2011) Çiftçi, Hakan; Testereci, H. Nur; Öktem, Zeki
Conducting poly(2-aminothiazole), PAT, was synthesized in acetonitrile with tetrabutylammonium tetrafluoroborate, TBAFB, as supporting electrolyte via constant potential electrolysis, CPE. Glassy carbon, GC, electrode was modified by immersing the electrode in a DMSO solution of PAT. Preconcentration of copper on polymer matrix was carried out at -0.7 V. The effects of preconcentration time and pH and Cu(II) concentration of the preconcentration solution on the stripping peak current of copper were studied.
Photocatalytic activity of polyaniline and neutral polyaniline for degradation of methylene blue and malachite green dyes under UV Light
(Springer, 2021) Haspulat Taymaz, Bircan; Taş, Recep; Kamış, Handan; Can, Muzaffer
A polyaniline (PANI) and neutral Polyaniline (NPANI) have been synthesized in acetonitrile-water mixture via the chemical oxidative polymerization of aniline. Scanning electron microscopy, FTIR spectra, UV-vis spectroscopy measurements were used to characterize the resulting PANI and NPANI. The photocatalytic activities of PANI and NPANI were investigated by the degradation of methylene blue (MB) and malachite green (MG) dyes in aqueous medium under UV light irradiation. MB and MG dyes completely degraded under UV light irradiation in the presence of NPANI after 60 and 75 min, respectively. The effect of dye type, irradiation time, dye concentration and photocatalyst amount on photocatalytic performance of PANI and NPANI have been examined under UV light irradiation. Three kinetic models have proposed for photocatalytic degradation of dyes by using PANI and NPANI under UV light illumination. This work explores the easy way to synthesize efficient PANI and NPANI polymers to degrade organic compound under both UV and visible light irradiations.
Physicochemical and biological assessment of boron nitride nanosheets-reinforced poly(2-hydroxyethylmethacrylate) composite for biomedical applications
(Elsevier, 2022) Doğan, Deniz; Metin, Ayşegül Ülkü
Research on mechanically advanced materials for biological applications involving load-bearing is in progress. Within this scope, this study is the first to propose the fabrication of bionanocomposites combining the different amounts of functionalized boron nitride nanosheets (f-BNNSs, 0-2.0 mg/mL) and poly(hydroxyethyl methac-rylate) (pHEMA). The pristine BN was exfoliated by microwave irradiation to access BNNSs at different powers and times. The as-exfoliated BNNSs were characterized by zeta-sizer, FTIR, XRD, and TEM, which showed that the BNNSs exhibited facile and processable features in tiny sizes. Bionanocomposites were fabricated by pho-topolymerization. The physical, chemical, and mechanical properties, hydrophilic behavior, and degradability of bionanocomposites were evaluated. The mechanical parameters such as Young's modulus and elongation per-centage at break showed that adding f-BNNSs up to 2.0 mg/mL significantly increased the mechanical strength of pHEMA without affecting the hydrophilicity, hemocompatibility, and cytotoxicity. Moreover, the hardness of pHEMA/f-BNNSs composites (38.56 MPa) was remarkably higher than that of pHEMA. There was no cytotoxicity recorded for fabricated bionanocomposites from the MTT assay. All nanocomposites exhibited superior anti-bacterial activities against E.coli and S.aureus compared with pHEMA. However, pHEMA/f-BNNSs composites were more effective against E.coli than S.aureus. While E.coli colonies was reduced 100% at all composites in an hour, S.aureus colonies was completely destroyed with pHEMA/1f-BNNSs and pHEMA/2f-BNNSs after 24 h in-cubation. The study's findings demonstrated that the mechanically improved pHEMA/f-BNNSs films could in-crease the application of pHEMA in biomedical fields.
Petroleum asphaltene-derived highly porous carbon for the efficient removal of pharmaceutical compounds in water
(Springer, 2022) Kabataş, Melike Burcu; Çetinkaya, Sevil
Highly porous carbons (PCs) were successfully developed through KOH chemical activation process from petroleum asphaltene for the efficient removal of pharmaceutical compounds (paracetamol and salicylic acid) from aqueous solution. The influences of activation temperature and the mixing types in chemical activation on the properties of the resulting PCs were investigated in detail by SEM, XRD, TGA, Raman, nitrogen adsorption-desorption, and CHNS elemental analyses. The PC with an extremely high surface area (2470 m(2)/g) was obtained by the impregnation method without modifier at an activation temperature of 850 degrees C. Adsorption kinetics was investigated with three kinetic models called the pseudo-first-order, the pseudo-second-order, and the intra-particle diffusion models, besides the adsorption equilibrium was analyzed using three widely used isotherm equations (Langmuir, Freundlich, and Temkin). The pseudo-second-order model was the best compatible with the experimental data for both organic compounds. This PC exhibited a high paracetamol adsorption capacity of 476.2 mg/g and a salicylic adsorption capacity of 500.0 mg/g in water. Thermodynamic analyzes confirmed that the adsorption was an exothermic process (Delta H-0 = - 18.63 kJ/mol) for paracetamol and an endothermic process (Delta H-0 = 53.96 kJ/mol) for salicylic acid. The linearized Freundlich and Langmuir models fitted the equilibrium data better than the others for paracetamol and salicylic acid, respectively.
Pervaporation performance of poly(vinyl alcohol)-graft-poly(N-hydroxymethyl acrylamide) membranes for dehydration of isopropyl alcohol-water mixture
(Wiley, 2022) Baysak, Fatma Kurşun; Işıklan, Nuran
In the present work, poly(N-hydroxymethyl acrylamide) grafted poly(vinyl alcohol) (PVA-g-PNHMA) membranes were developed for the dehydration of isopropyl alcohol (IPA) by the use of pervaporation method. The PVA-g-PNHMA membranes have been synthesized and their chemical composition and morphology have been characterized by Fourier transform infrared spectroscopy, C-13-nuclear magnetic resonance spectroscopy, X-ray diffractometry, differential scanning calorimetry, thermogravimetric analysis, and field emission scanning electron microscopy. The impacts of numerous factors such as temperature, feed concentration as well as membrane thickness on their pervaporation performance were investigated and the optimal conditions were found. With the increase in the grafting percentage of the PVA-g-PNHMA membrane, both flux and separation factor also increase. The PVA-g-PNHMA membrane with a grafting percentage of 34% revealed the best separation factor of 362 with a flux of 0.0085 kg/m(2).h for 12.6% mass of water in the feed solution. It has also been found that swelling behaviors of the membranes are consistent with all pervaporation results. Besides, permeation and diffusion activation energies were determined as 23.69 and 29.21 kJ/mol from the change of permeation flux with temperature. Based on the obtained outcomes, it is obvious that PVA-g-PNHMA membranes are quite efficient in the separation of IPA/water mixture via pervaporation.
One-pot green approach for rapid and effective anionic dye remediation: encapsulation within alginate nanocapsules
(Wiley, 2024) Alver, Erol; Doğan, Deniz; Mert Balaban, Hümeyra; Metin, Ayşegül Ülkü
BACKGROUNDThe encapsulation technique was applied to efficiently eliminate Congo red (CR) from aqueous solutions. During the ionotropic gelation between calcium (Ca2+) ions and alginate (AL), CR was effectively entrapped within the AL nanocapsules in a one-step process. Suitable conditions for efficient CR removal via encapsulation were revealed by the systematic optimization of parameters including pH, time and stirring speed, etc.RESULTSAccording to the experimental observations, the stirring rate and temperature were found to have an insignificant effect on the encapsulation of CR molecules. When the pH value of the medium was 3, the highest level of encapsulation efficiency was achieved in a period of 15 min. At a preliminary CR concentration of 2000 mg L-1 and pH 3, the encapsulation efficiency was calculated at approximate to 98.9%, with an encapsulation capacity of 2800 mg dye g-1 AL. The zeta potential values of AL and CR/AL nanocapsules were determined to be +7.05 eV and -14.9 eV, respectively, and the results showed that the particles tended to agglomerate. TEM micrographs also showed that the nanocapsules were nanosized and agglomerated. Soil and UV degradation studies showed that the dye-entrapped nanocapsules degraded remarkably. These results highlighted the great potential of encapsulation for dye removal in economical and practical applications.CONCLUSIONEncapsulation was confirmed to be an economical and practical technique for effectively eliminating CR from aqueous solutions. Under UV light irradiation, the dye molecules entrapped within alginate nanocapsules displayed photodegradation. (c) 2024 Society of Chemical Industry (SCI).
Novel magnetic poly(allyl methacrylate-co-glycidyl methacrylate) Fe3O4 nanoparticles: synthesis and evaluation as adsorbents for heavy metals
(Springer, 2024) Erduran, Nuran; Işılar, Özer
Magnetic nanoparticles have gained significant attention as versatile adsorbents in various studies due to their easy application, simple synthesis, cost-effectiveness, and reusability. In this study, we synthesized magnetic poly(AMA-co-GMA) nanoparticles (MAG) and modified them using allyl methacrylate (AMA) and glycidyl methacrylate (GMA). The epoxy groups on the nanoparticles were opened to introduce -OH, -NH2, and -SH functional groups. The structural properties of the synthesized nanoparticles were characterized by FTIR, their morphology by SEM-EDS, TEM, BET, and XRD, their magnetic properties by VSM, and the thermal properties by the TGA analysis. MAG and the modified nanoparticles (MAG-OH, MAG-NH2, and MAG-SH) were then employed in batch adsorption experiments for heavy metal ions, including Cd2+, Cu2+, Zn2+, Ni2+, Pb2+, and Hg2+. The effect of pH, contact time, ion concentration, and temperature on adsorption was investigated, and kinetic, isotherm, and thermodynamic parameters were determined. Pb2+ and Hg2+ exhibited higher adsorption capacities among the tested heavy metal ions, prompting further investigation with MAG and MAG-SH nanoparticles. The experimental data suggested that the adsorption followed the second order kinetic and Langmuir isotherm models. Overall, the results highlight the excellent potential of the synthesized magnetic nanoparticles for effectively removing heavy metal ions from wastewater.
Multi-stimuli-sensitive superparamagnetic κ-carrageenan based nanoparticles for controlled 5-fluorouracil delivery
(Elsevier, 2022) Geyik, Gülcan; Işıklan, Nuran
Herein, a novel multi-stimuli-sensitive nanoparticles with triple magnetic field, temperature, and pH-sensitive features was designed and developed as a drug nanocarrier for delivery of 5-fluorouracil (FL). For this purpose, dimethylaminoethyl methacrylate (DMA) was firstly grafted onto kappa-carrageenan (kappa-CG), and then kappa-CG-gPDMA copolymer was coated onto Fe3O4 nanoparticles via microwave-supported coprecipitation method. The prepared multi-functional magnetic nanoparticles were characterized by UV, FTIR, XRD, TEM, Zeta-sizer, and VSM analyses to confirm the formation of superparamagnetic Fe3O4@kappa-CG-g-PDMA structure. The in vitro FL release of the nanoparticles was investigated at 48 and 37 degrees C in different pH conditions and exhibited good pH- and temperature-sensitive behavior. Furthermore, the effects of graft yield and magnetic field on FL release were explored. When the magnetic field was applied at 100 kHz, the release of FL increased rapidly, demonstrating that nanoparticles had magnetic field-sensitive features. According to the results, the designed Fe3O4@kappa-CG-g-PDMA@FL nanoparticles can be considered as a smart drug delivery system for cancer therapy due to its high entrapment efficiency, slow and multi-stimuli-triggered FL release performance, and satisfactory magnetic properties.
Multifunctional aptamer-conjugated magnetite graphene oxide/chlorin e6 nanocomposite for combined chemo-phototherapy
(Elsevier, 2022) Işıklan, Nuran; Hussien, Nizamudin Awel; Türk, Mustafa
Herein, aptamer-functionalized magnetite Fe3O4@graphene oxide/photosensitizer nanocomposite was designed and prepared for chemo-photothermal/photodynamic therapies. Chlorin e6 (Ce6, as a photosensitizer) is used to conjugate with magnetite graphene oxide (Fe3O4@GO). The structure of Fe3O4@GO@Ce6 nanocomposite was characterized by using FTIR, UV, TGA, XRD, VSM and TEM methods. An antineoplastic drug, paclitaxel (Pac), was loaded onto Fe3O4@GO@Ce6 nanocomposite, forming a Fe3O4@GO@Ce6@Pac nanocomplex. The Fe3O4@GO@Ce6 nanocomposite was functionalized with aptamer (Apt) for selective killing of MCF-7 tumor cells. Fe3O4@GO@Ce6@Pac nanocomposite offers a notably enhanced tumor cell photodynamic destruction impact compared to free Ce6. It is displayed that the photothermal impact of magnetite Fe3O4@GO@Ce6 nanocomposite can be used to promote the Ce6 release when irradiated to a near-infrared laser at a low power density, further improving the photodynamic therapy efficiency on tumor cells. It is observed that the Fe3O4@GO@Ce6 nanocomposite possessed good colloidal/photo stability, biocompatibility, and high loading capacity for Pac. Furthermore, compared to the free Ce6, the Fe3O4@GO@Ce6@Apt-Pac nanocomposite display significantly enhanced photodynamic efficacy. Due to its intrinsic optical features, ultrahigh specific surface area, targeting ability, and unique physical interactions with aromatic active agents, Fe3O4@GO@Ce6@Apt-Pac is a promising new nanomaterial for medical and biological applications.
Microextraction methods
(Yildiz Technical Univ, 2012) Alver, Erol; Demirci, Ayla; Özcimder, Mustafa
Accurate, rapid and economic qualitative and quantitative analysis of trace amount substances in biological, environmental and food products is an important issue. Mostly, such substances must be taken from the matrix (separation) and concentrated (enrichment) before determining with analytical equipment. For these processes liquid-liquid, solid-liquid extraction and solid phase extraction are commonly used. However these methods are recently replaced by microexraction methods minimizing organic solvent consumption, simplifying sample preparation steps, providing high enrichment rates and appropriate to automation.
Boron nitride decorated poly(vinyl alcohol)/poly(acrylic acid) composite nanofibers: A promising material for biomedical applications
(Elsevier, 2023) Dogan, Deniz; Karaduman, F. Rabia; Horzum, Nesrin; Metin, Ayşegül Ülkü
In this study, polyvinyl alcohol (PVA) and polyacrylic acid (PAA) nanofibers loaded with boron nitride nano-particles (mBN) were fabricated by using electrospinning and crosslinked by heat treatment. The physical, chemical, and mechanical properties, hydrophilic behavior, and degradability of composite nanofibers were evaluated. The mechanical properties such as elastic modulus, elongation percentage at the break, and mechanical strength of PVA/PAA nanofibers improved with mBN loading. The thermal conductivity of composite nanofibers reached 0.12 W/m center dot K at mBN content of 1.0 wt% due to the continuous heat conduction pathways of mBN. In the meantime, while there was no cytotoxicity recorded for both L929 and HUVEC cell lines for all composite nanofibers, the antimicrobial efficiency improved with the incorporation of mBN compared with PVA/PAA and recorded as 68.8% and 75.1% for Escherichia coli and Staphylococcus aureus, respectively. On this basis, the present work proposes a promising biomaterial for biomedical applications such as dual drug delivery, particularly including both hydrophobic and hydrophilic drugs or wound dressing.
Beyond Conventional: Antibacterial, Antioxidant, and Photocatalytic Properties of Nanofibers Featuring Metal-Oxide-Modified Boron Nitride Nanoparticles
(Amer Chemical Soc, 2024) Horzum, Nesrin; Doğan, Deniz; Karaduman, Fatma Rabia; Metin, Ayşegül Ülkü
CuO-, ZrO2-, and ZnO-immobilized functional boron nitride (fBN) nanoparticles were synthesized by an environmentally friendly approach using a Stevia rebaudiana extract. Metal-oxide-immobilized fBN nanoparticles (fBN/MO)-incorporated (1 wt %) polyvinyl alcohol/poly(acrylic acid) composite nanofibers were fabricated by electrospinning, and their antibacterial, antioxidant, and photocatalytic properties were investigated. fBN/CuO and fBN/ZnO nanoparticles were distributed randomly, showcasing nonuniform geometries besides polygonal-shaped fBN/ZrO2 nanoparticles. fBN/MO nanoparticles exhibited a uniform dispersion along the composite nanofibers, with diameters between 115 and 160 nm. The incorporation of fBN/MO nanoparticles into the composite nanofibers (0.074-0.753 W/mK) resulted in an improvement in both thermal stability and conductivity when compared with PVA/PAA nanofibers (0.063 W/mK). fBN/MO-modified composite nanofibers exhibited an antibacterial efficacy exceeding 99% against Streptococcus mutans, Acinetobacter baumannii, Escherichia coli, and Staphylococcus aureus, augmenting their antioxidant properties. The modified composite nanofibers, particularly those incorporating fBN/ZrO2 nanoparticles, exhibited effective photocatalytic remediation against methylene blue (MB) with the highest activity, attributed to their favorable morphological and optoelectronic properties, resulting in a remarkably more than 20-fold improvement. Enhanced stability for repeated treatment of MB for a minimum of three cycles was achieved. The multifunctional nature of nanofibers unveils synergistic antibacterial, antioxidant, and photodegradation effects, positioning them as promising for biomaterials and water disinfection.

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