Browsing by Subject "Nanofibrous membranes"
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Item Open Access Biocatalytic protein membranes fabricated by electrospinning(Elsevier B.V., 2016) Kabay, G.; Kaleli, G.; Sultanova, Z.; Ölmez, T. T.; Şeker, U. Ö. Ş.; Mutlu, M.In this study, a protein-based catalytic membrane was produced by electrospinning. Membrane activity was characterised in terms of response current for various glucose concentrations. We focused on the preparation of a scaffold by converting a globular protein to other structural forms using catastrophic solvents. A scaffolding protein, bovine serum albumin, and an enzyme, glucose oxidase (GOD), were selected as a model natural carrier matrix and a biologically active agent, respectively. Beta-mercaptoethanol (β-ME) was used to convert the globular protein to an amyloid-like form. A structural stabilising agent, 2,2,2-triflouroethanol (TFE), was used to maintain the final α-helical structure of the amyloid-like protein. The TFE:PBS (phosphate-buffered saline) ratio and various electrospinning parameters were analysed to minimise activity loss. Using this approach, we applied electrospinning to an active enzyme to obtain biocatalytic nanofibrous membranes. After optimising the protein electrospinning process, the activities of the protein nanofibrous membranes were monitored. GOD remained active in the new membrane structure. The highest enzyme activity was observed for the membranes prepared with a 1.5:1 (v:v) TFE:PBS solvent ratio. In that particular case, the immobilized enzyme created a current of 0.7 μA and the apparent activity was 2547 ± 132 U/m2.Item Open Access Electrospun nylon 6,6 nanofibers functionalized with cyclodextrins for removal of toluene vapor(John Wiley and Sons Inc., 2015) Kayaci, F.; Sen, H. S.; Durgun, Engin; Uyar, TamerFunctional nylon 6,6 nanofibers incorporating cyclodextrins (CD) were developed via electrospinning. Enhanced thermal stability of the nylon 6,6/CD nanofibers was observed due to interaction between CD and nylon 6,6. X-ray photoelectron spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy studies indicated the existence of some CD molecules on the surface of the nanofibers. Electrospun nylon 6,6 nanofibers without having CD were ineffective for entrapment of toluene vapor from the environment, whereas nylon 6,6/CD nanofibrous membranes can effectively entrap toluene vapor from the surrounding by taking advantage of the high surface-volume ratio of nanofibers with the added advantage of inclusion complexation capability of CD presenting on the nanofiber surface. The modeling studies for formation of inclusion complex between CD and toluene were also performed by using ab initio techniques. Our results suggest that nylon 6,6/CD nanofibrous membranes may have potential to be used as air filters for the removal of organic vapor waste from surroundings.Item Open Access Fabrication of cellulose acetate/polybenzoxazine cross-linked electrospun nanofibrous membrane for water treatment(Elsevier, 2017-12) Ertaş, Yelda; Uyar, TamerHerein, polybenzoxazine based cross-linked cellulose acetate nanofibrous membrane exhibiting enhanced thermal/mechanical properties and improved adsorption efficiency was successfully produced via electrospinning and thermal curing. Initially, suitable solution composition was determined by varying the amount of the benzoxazine (BA-a) resin, cellulose acetate (CA) and citric acid (CTR) to obtain uniform nanofibrous membrane via electrospinning. Subsequently, thermal curing was performed by step-wise at 150, 175, 200 and 225 °C to obtain cross-linked composite nanofibrous membranes. SEM images and solubility experiments demonstrated that most favorable result was obtained from the 10% (w/v) CA, 5% (w/v) BA-a and 1% (w/v) CTR composition and cross-linked nanofibrous membrane (CA10/PolyBA-a5/CTR1) was obtained after the thermal curing. Chemical structural changes (ring opening) occurred by thermal curing revealed successful cross-linking of BA-a in the composite nanofibrous membrane. Thermal, mechanical and adsorption performance of pristine CA and CA10/PolyBA-a5/CTR1 nanofibrous membranes were studied. Char yield of the pristine CA nanofibrous membrane has increased notably from 12 to 24.7% for composite CA10/PolyBA-a5/CTR1 membrane. When compared to pristine CA membrane, CA10/PolyBA-a5/CTR1 nanofibrous membrane has shown superior mechanical properties having tensile strength and Young's modulus of 8.64 ± 0.63 MPa and 213.87 ± 30.79 MPa, respectively. Finally, adsorption performance of pristine CA and CA10/PolyBA-a5/CTR1 nanofibrous membranes was examined by a model polycyclic aromatic hydrocarbon (PAH) compound (i.e. phenanthrene) in aqueous solution, in which CA10/PolyBA-a5/CTR1 nanofibrous membrane has shown better removal efficiency (98.5%) and adsorption capacity (592 μg/g).Item Open Access Ultrasensitive electrospun fluorescent nanofibrous membrane for rapid visual colorimetric detection of H2O2(Springer Verlag, 2016-02) Senthamizhan A.; Balusamy, B.; Aytac Z.; Uyar, TamerWe report herein a flexible fluorescent nanofibrous membrane (FNFM) prepared by decorating the gold nanocluster (AuNC) on electrospun polysulfone nanofibrous membrane for rapid visual colorimetric detection of H2O2. The provision of AuNC coupled to NFM has proven to be advantageous for facile and quick visualization of the obtained results, permitting instant, selective, and on-site detection. We strongly suggest that the fast response time is ascribed to the enhanced probabilities of interaction with AuNC located at the surface of NF. It has been observed that the color change from red to blue is dependent on the concentration, which is exclusively selective for hydrogen peroxide. The detection limit has been found to be 500 nM using confocal laser scanning microscope (CLSM), visually recognizable with good accuracy and stability. A systematic comparison was performed between the sensing performance of FNFM and AuNC solution. The underlying sensing mechanism is demonstrated using UV spectra, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The corresponding disappearance of the characteristic emissions of gold nanoclusters and the emergence of a localized surface plasmon resonance (LSPR) band, stressing this unique characteristic of gold nanoparticles. Hence, it is evident that the conversion of nanoparticles from nanoclusters has taken place in the presence of H2O2. Our work here has paved a new path for the detection of bioanalytes, highlighting the merits of rapid readout, sensitivity, and user-friendliness.