Browsing by Author "Celebioglu, A."

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Open Access
Antibacterial nanofibers of pullulan/tetracycline-cyclodextrin inclusion complexes for fast-disintegrating oral drug delivery
(Elsevier Inc., 2021-12-08) Hsiung, E.; Celebioglu, A.; Chowdhury, R.; Kilic, M. E.; Durgun, Engin; Altier, C.; Uyar, T.
Tetracycline is a widely used antibiotic suffering from poor water solubility and low bioavailability. Here, hydroxypropyl-beta-cyclodextrin (HPβCD) was used to form inclusion complexes (IC) of tetracycline with 2:1 M ratio (CD:drug). Then, tetracycline-HPβCD-IC was mixed with pullulan- a non-toxic, water-soluble biopolymer - to form nanofibrous webs via electrospinning. The electrospinning of pullulan/tetracycline-HPβCD-IC was yielded into defect-free nanofibers collected in the form of a self-standing and flexible material with the loading capacity of ∼ 7.7 % (w/w). Pullulan/tetracycline nanofibers was also generated as control sample having the same drug loading. Tetracycline was found in the amorphous state in case of pullulan/tetracycline-HPβCD nanofibers due to inclusion complexation. Through inclusion complexation with HPβCD, enhanced aqueous solubility and faster release profile were provided for pullulan/tetracycline-HPβCD-IC nanofibers compared to pullulan/tetracycline one. Additionally, pullulan/tetracycline-HPβCD-IC nanofibers readily disintegrated when wetted with artificial saliva while pullulan/tetracycline nanofibers were not completely absorbed by the same simulate environment. Electrospun nanofibers showed promising antibacterial activity against both gram-positive and gram-negative bacteria. Briefly, our findings indicated that pullulan/tetracycline-HPβCD-IC nanofibers could be an attractive material as orally fast disintegrating drug delivery system for the desired antibiotic treatment thanks to its promising physicochemical and antibacterial properties.
Open Access
Efficient ammonium removal from aquatic environments by Acinetobacter calcoaceticus STB1 immobilized on an electrospun cellulose acetate nanofibrous web
(Royal Society of Chemistry, 2013-07-09) Sarioglu, O. F.; Yasa, O.; Celebioglu, A.; Uyar, T.; Tekinay, T.
A novel biocomposite material was developed by immobilizing an ammonia-oxidizing bacterial strain, Acinetobacter calcoaceticus STB1, on an electrospun porous cellulose acetate (CA) nanofibrous web. Ammonium removal characteristics of the STB1 immobilized CA nanofibrous web were determined at varying initial ammonium concentrations, and removal rates of 100%, 98.5% and 72% were observed within 48 h for 50 mg L-1, 100 mg L-1 and 200 mg L-1 samples, respectively. Most of the ammonia is inferred to be converted into nitrogen or is accumulated as bacterial biomass, as only trace amounts of ammonium were converted into nitrite or nitrate. Reusability test results indicate that, at an initial ammonium concentration of 100 mg L-1, bacteria-immobilized CA nanofibrous webs can be reused for at least 5 cycles. SEM images of the STB1/CA nanofibrous web after five cycles of reuse and rigorous washing demonstrate that bacterial biofilms strongly adhere to nanofiber surfaces.
Open Access
Electron-phonon interaction in bulk layered graphene and its oxide in the presence of alcohols in a device: Equilibrium molecular doping
(The Royal Society of Chemistry, 2014-08-22) Vempati, S.; Celebioglu, A.; Uyar, T.
We report on electron phonon interactions in bulk layered graphene (GRA) and its oxide (GO) under bias when exposed to 1° or 2° alcohol vapors, where we have focused on the change of Raman intensity of G and D bands as a function of the bias across the device. In addition to the softening of phonons we have observed a systematic variation in the intensity for D and G bands which is directly related to guest molecules and intrinsic surface nature of GRA and GO. Although the guest molecules withdraw electrons from GRA or GO, the intrinsic nature of the host material has caused mutually contrasting behaviour in IV-characteristics, where the conductance of the former decreases while it increases for the latter. The results from IV-spectra and the intensity maps of D and G bands are juxtaposed and the changes are analyzed with respect to surface and functional group interactions. In the context of doping, it is interesting to see that under equilibrium molecular charge transfer (top-gate like), the intensity ratios of 2D and G bands are not constant in contrast to a previous study [Phys. Rev. B., 2009, 80, 165413] in which such a ratio is invariant in the field effect configuration. © the Partner Organisations 2014.
Open Access
Electrospun crosslinked poly-cyclodextrin nanofibers: highly efficient molecular filtration thru host-guest inclusion complexation
(Nature Publishing Group, 2017) Celebioglu, A.; Yildiz, Z. I.; Uyar, T.
Water pollution is a serious concern for public health and environment in today's world; hence, there exists a strong demand to develop cost-effective, sustainable and eco-friendly membranes. Here, we produce a highly efficient molecular filter membrane based on bio-renewable material; cyclic oligosaccaharides known as cyclodextrins (CD). Crosslinked insoluble poly-CD nanofibers are produced by using electrospinning technique in the absence of any additional polymeric carrier. Poly-CD nanofibrous membrane exhibit significant affinity to a common class of organic pollutant (i.e. methylene blue (MB)). Remarkably, the electrospun poly-CD nanofibrous web can outdistance the commonly used filter material (i.e. activated carbon) in terms of removal capacity. The flexible and free-standing poly-CD nanofibrous membrane depicted outstanding filtration performance. We estimate of above 90% removal efficiency for highly concentrated solutions of MB pollutant (40 mg/L) under extremely high flux (3840 Lm-2h-1). Essentially, these poly-CD nanofibrous webs demonstrate quite rapid uptake of MB from liquid environment. Overall, bio-based flexible electrospun poly-CD nanofibrous membrane represents a highly efficient molecular filter for wastewater treatment.
Open Access
Electrospun functional nanofibers
(Fiber Society, 2010) Kayaci F.; Celebioglu, A.; Deniz, A.E.; Uyar, T.
[No abstract available]
Open Access
Functional polymeric nanofibers via electrospinning
(2012) Uyar, T.; Kayacı, F.; Celebioglu, A.; Aytac, Z.; Ertas, Y.
Open Access
Ondansetron/Cyclodextrin inclusion complex nanofibrous webs for potential orally fast-disintegrating antiemetic drug delivery
(Elsevier, 2022-07-25) Hsiung, E.; Celebioglu, A.; Emin Kilic, M.; Durgun, Engin
Ondansetron (ODS) is an effective antiemetic drug which suffers from limited solubility and bioavailability during oral administration due to first-pass metabolism. However, these limitations can be mitigated through inclusion complexation with cyclodextrins (CDs). In this study, we have reported the electrospinning of polymer-free, free-standing ODS/CD nanofibrous webs (NW), a promising approach for developing a fast-disintegrating delivery system of an antiemetic drug molecule. Highly water soluble hydroxypropyl-beta-cyclodextrins (HPβCD) were used as both complexation agent and electrospinning matrix. The computational study revealed that the 1/2 (drug/CD) stoichiometry was more favorable compared to 1/1. The ODS/HPβCD NW was obtained with higher loading efficiency (∼96 %) compared to the control sample of ODS/polyvinyl alcohol (PVA) NW (∼80 %). The amorphous distribution of ODS raised by complexation and the highly water-soluble nature of HPβCD resulted into faster and better release profile and quite faster disintegration property (∼2 s) in artificial saliva than polymeric ODS/PVA NW. Here, ODS/HPβCD NW was generated in the absence of a toxic solvent or chemical to enable the drug loading in an amorphous state. From all reasons above, ODS/HPβCD NW might be a promising alternative to the polymeric based systems for the purpose of fast-disintegrating oral drug delivery.
Open Access
Orally fast-disintegrating resveratrol/cyclodextrin nanofibrous films as a potential antioxidant dietary supplement
(American Chemical Society, 2022-03-04) Celebioglu, A.; Tekant, D; Kilic, M.E.; Tekant, D.; Durgun, Engin; Uyar, T.
Encapsulation of dietary supplements into electrospun cyclodextrin (CD) inclusion complex (IC) nanofibers can pave the way for the development of novel delivery systems with orally fast-disintegrating properties. Here, resveratrol/CD-IC nanofibrous films were fabricated using the electrospinning technique. Resveratrol is a well-known bioactive agent with its antioxidant potential, and it is commonly used in the formulation of dietary supplements. Here, the hydroxypropylated (HP-) βCD and γCD were used for both encapsulation of resveratrol and the electrospinning of free-standing nanofibrous films. SEM imaging confirmed the uniform fibrous morphology of electrospun films. The encapsulation and amorphization of resveratrol by inclusion complexation were verified using various techniques including FTIR, 1H NMR, XRD, DSC, TGA, and computational modeling. Besides the results of all these techniques, phase solubility studies also revealed the more favorable complex formation of resveratrol with HPβCD compared to HP γCD. Nanofibrous films were obtained having ∼100% loading efficiency without a loss during the process. The amorphous distribution of resveratrol and the unique properties of nanofibers ensured the fast disintegration of nanofibrous films in the saliva simulation. The enhanced solubility of resveratrol also ensured an improved antioxidant property. The polymeric resveratrol/pullulan nanofibrous film was also formed as a control sample. CD-IC nanofibrous films showed faster disintegration/dissolution, higher/faster release profile, and significantly better antioxidant potential compared to resveratrol/pullulan-based samples.
Open Access
Reusable bacteria immobilized electrospun nanofibrous webs for decolorization of methylene blue dye in wastewater treatment
(Royal Society of Chemistry, 2014-07-03) San, N. O.; Celebioglu, A.; Tümtaş, Y.; Uyar, T.; Tekinay, T.
In our study, an electrospun cellulose acetate nanofibrous web (CA-NFW) was found to be quite effective in immobilizing bacterial cells. Here, decolorization of methylene blue (MB) dye in aqueous medium was achieved by using three types of bacteria (Aeromonas eucrenophila, Clavibacter michiganensis and Pseudomonas aeruginosa) immobilized on the CA-NFW. The decolorization time (0-48 h) and different MB dye concentrations (20-500 mg L-1) were studied to elucidate the maximum MB dye removal by the bacteria immobilized CA-NFWs. The effective dye decolorization was achieved within 24 hours and MB dye removal was similar to 95%. Interestingly, MB dye decolorization performance of bacteria immobilized CA-NFWs was quite close to that of free bacteria. We have also tested the reusability of bacteria immobilized NFWs after four cycles and similar to 45% of the dye decolorization capacity was obtained at the end of the 4th cycle. These results are quite promising and therefore suggest that bacteria immobilized electrospun NFWs could be quite applicable for the decolorization of dyes in wastewater due to their versatility and reusability.
Open Access
Surface decoration of Pt nanoparticles via ALD with TiO2 protective layer on polymeric nanofibers as flexible and reusable heterogeneous nanocatalysts
(Nature Publishing Group, 2017) Celebioglu, A.; Ranjith, K. S.; Eren, H.; Bıyıklı, Necmi; Uyar, T.
Coupling the functional nanoheterostructures over the flexible polymeric nanofibrous membranes through electrospinning followed by the atomic layer deposition (ALD), here we presented a high surface area platform as flexible and reusable heterogeneous nanocatalysts. Here, we show the ALD of titanium dioxide (TiO2) protective nanolayer onto the electrospun polyacrylonitrile (PAN) nanofibrous web and then platinum nanoparticles (Pt-NP) decoration was performed by ALD onto TiO2 coated PAN nanofibers. The free-standing and flexible Pt-NP/TiO2-PAN nanofibrous web showed the enhancive reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) within 45 seconds though the hydrogenation process with the degradation rate of 0.1102 s-1. The TiO2 protective layer on the PAN polymeric nanofibers was presented as an effective route to enhance the attachment of Pt-NP and to improve the structure stability of polymeric nanofibrous substrate. Commendable enhancement in the catalytic activity with the catalytic dosage and the durability after the reusing cycles were investigated over the reduction of 4-NP. Even after multiple usage, the Pt-NP/TiO2-PAN nanofibrous webs were stable with the flexible nature with the presence of Pt and TiO2 on its surface.