Browsing by Subject "Growth inhibition"

Now showing 1 - 5 of 5

Open Access
Antibacterial electrospun zein nanofibrous web encapsulating thymol/cyclodextrin-inclusion complex for food packaging
(Elsevier, 2017-10) Aytac Z.; Ipek, S.; Durgun, Engin; Tekinay, T.; Uyar, Tamer
Thymol (THY)/γ-Cyclodextrin(γ-CD) inclusion complex (IC) encapsulated electrospun zein nanofibrous webs (zein-THY/γ-CD-IC-NF) were fabricated as a food packaging material. The formation of THY/γ-CD-IC (1:1 and 2:1) was proved by experimental (X-ray diffraction (XRD), thermal gravimetric analysis (TGA), 1H NMR) and computational techniques. THY/γ-CD-IC (2:1) exhibited higher preservation rate and stability than THY/γ-CD-IC (1:1). It is worth mentioning that zein-THY/γ-CD-IC-NF (2:1) preserved much more THY as observed in TGA and stability of THY/γ-CD-IC (2:1) was higher, as shown by a modelling study. Therefore, much more THY was released from zein-THY/γ-CD-IC-NF (2:1) than zein-THY-NF and zein-THY/γ-CD-IC-NF (1:1). Similarly, antibacterial activity of zein-THY/γ-CD-IC-NF (2:1) was higher than zein-THY-NF and zein-THY/γ-CD-IC-NF (1:1). It was demonstrated that zein-THY/γ-CD-IC-NF (2:1) was most effective in inhibiting the growth of bacteria on meat samples. These webs show potential application as an antibacterial food packaging material.
Open Access
Area-selective atomic layer deposition using an inductively coupled plasma polymerized fluorocarbon layer: A case study for metal oxides
(American Chemical Society, 2016) Haider, A.; Deminskyi, P.; Khan, T. M.; Eren, H.; Bıyıklı, Necmi
Area-selective atomic layer deposition (AS-ALD) has attracted immense attention in recent years for self-aligned accurate pattern placement with subnanometer thickness control. Here, we demonstrate a methodology to achieve AS-ALD by using inductively couple plasma (ICP) grown fluorocarbon polymer film as hydrophobic blocking layer for selective deposition. Our approach has been tested for metal-oxide materials including ZnO, Al2O3, and HfO2. Contact angle, X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometer, and scanning electron microscopy (SEM) measurements were performed to investigate the blocking ability of plasma polymerized fluorocarbon layers against ALD-grown metal-oxide films. A considerable growth inhibition for ZnO has been observed on fluorocarbon coated Si(100) surfaces, while the same polymerized surface caused a relatively slow nucleation for HfO2 films. No growth selectivity was obtained for Al2O3 films, displaying almost the same nucleation behavior on Si and fluorocarbon surfaces. Thin film patterning has been demonstrated using this strategy by growing ZnO on lithographically patterned fluorocarbon/Si samples. High resolution SEM images and XPS line scan confirmed the successful patterning of ZnO up to a film thickness of ∼15 nm. © 2016 American Chemical Society.
Open Access
Effects of laser ablated silver nanoparticles on Lemna minor
(Elsevier, 2014) Üçüncü, E.; Özkan, A. D.; Kurşungöz, C.; Ülger, Z. E.; Ölmez, T. T.; Tekinay, T.; Ortaç, B.; Tunca E.
Open Access
Novel anti-HER2 monoclonal antibodies: synergy and antagonism with tumor necrosis factor-α
(BioMed Central, 2012) Ceran, Ceyhan; Çokol, M.; Cingöz, S.; Taşan, İpek; Öztürk, Mehmet; Yağcı, Tamer
Background: One-third of breast cancers display amplifications of the ERBB2 gene encoding the HER2 kinase receptor. Trastuzumab, a humanized antibody directed against an epitope on subdomain IV of the extracellular domain of HER2 is used for therapy of HER2-overexpressing mammary tumors. However, many tumors are either natively resistant or acquire resistance against Trastuzumab. Antibodies directed to different epitopes on the extracellular domain of HER2 are promising candidates for replacement or combinatorial therapy. For example, Pertuzumab that binds to subdomain II of HER2 extracellular domain and inhibits receptor dimerization is under clinical trial. Alternative antibodies directed to novel HER2 epitopes may serve as additional tools for breast cancer therapy. Our aim was to generate novel anti-HER2 monoclonal antibodies inhibiting the growth of breast cancer cells, either alone or in combination with tumor necrosis factor-α (TNF-α). Methods: Mice were immunized against SK-BR-3 cells and recombinant HER2 extracellular domain protein to produce monoclonal antibodies. Anti-HER2 antibodies were characterized with breast cancer cell lines using immunofluorescence, flow cytometry, immunoprecipitation, western blot techniques. Antibody epitopes were localized using plasmids encoding recombinant HER2 protein variants. Antibodies, either alone or in combination with TNF-α, were tested for their effects on breast cancer cell proliferation. Results: We produced five new anti-HER2 monoclonal antibodies, all directed against conformational epitope or epitopes restricted to the native form of the extracellular domain. When tested alone, some antibodies inhibited modestly but significantly the growth of SK-BR-3, BT-474 and MDA-MB-361 cells displaying ERBB2 amplification. They had no detectable effect on MCF-7 and T47D cells lacking ERBB2 amplification. When tested in combination with TNF-α, antibodies acted synergistically on SK-BR-3 cells, but antagonistically on BT-474 cells. A representative anti-HER2 antibody inhibited Akt and ERK1/2 phosphorylation leading to cyclin D1 accumulation and growth arrest in SK-BR-3 cells, independently from TNF-α. Conclusions: Novel antibodies against extracellular domain of HER2 may serve as potent anti-cancer bioactive molecules. Cell-dependent synergy and antagonism between anti-HER2 antibodies and TNF-α provide evidence for a complex interplay between HER2 and TNF-α signaling pathways. Such complexity may drastically affect the outcome of HER2-directed therapeutic interventions.
Open Access
Toxicity of lanthanum oxide (La2O3) nanoparticles in aquatic environments
(Royal Society of Chemistry, 2015) Balusamy, B.; Taştan, B. E.; Ergen, S. F.; Uyar, Tamer; Tekinay, T.
This study demonstrates the acute toxicity of lanthanum oxide nanoparticles (La2O3 NP) on two sentinel aquatic species, fresh-water microalgae Chlorella sp. and the crustacean Daphnia magna. The morphology, size and charge of the nanoparticles were systematically studied. The algal growth inhibition assay confirmed absence of toxic effects of La2O3 NP on Chlorella sp., even at higher concentration (1000 mg L-1) after 72 h exposure. Similarly, no significant toxic effects were observed on D. magna at concentrations of 250 mg L-1 or less, and considerable toxic effects were noted in higher concentrations (effective concentration [EC50] 500 mg L-1; lethal dose [LD50] 1000 mg L-1). In addition, attachment of La2O3 NP on aquatic species was demonstrated using microscopy analysis. This study proved to be beneficial in understanding acute toxicity in order to provide environmental protection as part of risk assessment strategies.