Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 2Citation - Scopus: 2Evaluating the Performance of Conventional Daf and Posidaf Processes for Cyanobacteria Separation at a Pilot Plant Scale(IWA Publishing, 2022) Yap, Russell K.L.; Rao, N. R.H.; Holmes, M.; Whittaker, Michael; Stuetz, Richard M.; Jefferson, Bruce; Bulmuş, Volga; Peirson, William Leslie; Henderson, R. K.In this work, a commercially available water treatment polymer poly(N,N-diallyl-N,N-dimethylammonium chloride) (PDADMAC) and a hydrophobically modified polymer (HMP) designed to adhere to bubble surfaces were applied for the first time in the novel Posi-dissolved air flotation process (PosiDAF) that uses polymer-modified bubbles, at pilot-scale for the treatment of waste stabilisation pond samples rich in algae. It was found that PDADMAC in PosiDAF gave comparable removal to that achieved using conventional DAF at .95% cell separation. Furthermore, the float layer was more uniform and thicker with up to 8% solid contents compared to conventional DAF, which comprised discrete floc clusters with an average solid concentration of ∼4.1%. In contrast to the use of PDADMAC, the application of the HMP did not achieve similarly good separation at pilot scale. It was hypothesised that this may be due to the micellisation of the HMP on the bubble surface, creating unstable bubbles that coalesced and prevented polymer-bubble-cell interactions, which are crucial for effective cell separation. On comparison of the costs of PosiDAF and conventional DAF, it was found that PosiDAF resulted in cost-savings of up to 74% due to low chemical consumption. In summary, PosiDAF reduced chemical cost and increased solid contents in the metal-free float.Article Citation - Scopus: 1A Diaminoethane Motif Bearing Low Molecular Weight Polymer as a New Nucleic Acid Delivery Agent(Elsevier, 2021) Zelcak, Aykut; Ünal, Yağmur Ceren; Meşe, Gülistan; Bulmuş, VolgaAmong polymer-based gene delivery systems, poly(ethylene imine) (PEI) stands out as an effective polycation. However, the toxic effects of PEI especially at higher molecular weights limit its usage. Although the effects of PEI's architecture and molecular weight on gene delivery is controversial in literature, low molecular weight PEI appears to be efficient at transfection while having lower toxicity. Herein, as an alternative to low molecular weight, linear PEI, a methacrylate polymer bearing diamimoethane motifs, poly(2-((2-aminoethyl)amino)ethyl methacrylate) (P(AEAEMA)), was evaluated in vitro as a new nucleic acid delivery agent. P(AEAEMA) (8 kDa) showed low toxicity on Skov-3-luc and NIH/3T3 cell lines at polymer concentrations where PEI (8 kDa) was highly toxic. P(AEAEMA) could efficiently form complexes with siRNA at an N/P ratio of 2 as shown by gel electrophoresis. The diameter of P(AEAEMA)-siRNA complexes was found to be significantly lower than PEIsiRNA complexes almost at all tested N/P ratios. P(AEAEMA) could improve the stability of siRNA in serum containing media by protecting the siRNA against serum nucleases. siRNA and pDNA transfection efficiency of P (AEAEMA) on luciferase expressing Skov-3-luc cell line and HEK 293T cell line, respectively was found to be comparable to well-known nucleic acid carrier, PEI. The transfection efficiency of both P(AEAEMA) and PEI was found to be cell-type-dependent. None of the polymers were able to transfect MDA-MB-231 cells with siRNA or pDNA.Article Citation - WoS: 5Citation - Scopus: 6Efficient Synthesis of Crgd Functionalized Polymers as Building Blocks of Targeted Drug Delivery Systems(Elsevier Ltd., 2018) Thankappan, Hajeeth; Zelçak, Aykut; Taykoz, Damla; Bulmuş, VolgaSynthetic peptides with cyclic arginine-glycine-aspartate motif (cRGD) play an important role in cell recognition and cell adhesion. cRGD-decorated soluble polymers and polymeric nanoparticles have been increasingly used for cell-specific delivery of antitumor drugs. While the significance of cRGD modification for tumor cell-specific targeting of polymeric carriers is well-accepted, straightforward procedures ensuring the fidelity of cRGD modification of polymeric systems are still lacking. Herein, we have reported an in-situ polymerization approach for synthesis of cRGD-end-functionalized well-defined polymers as potential building blocks of targeted drug delivery systems. A new cRGD peptide functionalized RAFT agent was synthesized as confirmed by MALDI-TOF and 1H NMR spectroscopy. The ability of this RAFT agent to control polymerizations was then tested using two different monomers oligoethyleneglycol acrylate and t-butyl methacrylate. The RAFT-controlled character of polymerizations and the living characteristic of the synthesized polymers were investigated through a series of kinetic experiments. The cytotoxicity and targeting capability of cRGD-functionalized OEGA polymers were investigated using cell lines expressing αvβ3 integrins at varying extents.Article Citation - WoS: 36Citation - Scopus: 38Effect of Molecular Architecture on Cell Interactions and Stealth Properties of Peg(American Chemical Society, 2017) Özer, İmran; Tomak, Aysel; Zareie, Hadi M.; Baran, Yusuf; Bulmuş, VolgaPEGylation, covalent attachment of PEG to therapeutic biomolecules, in which suboptimal pharmacokinetic profiles limiting their therapeutic utility are of concern, is a widely applied technology. However, this technology has been challenged by reduced bioactivity of biomolecules upon PEGylation and immunogenicity of PEG triggering immune response and abrogating clinical efficacy, which collectively necessitate development of stealth polymer alternatives. Here we demonstrate that comb-shape poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA), a stealth polymer alternative, has a more compact structure than PEG and self-organize into nanoparticles in a molecular weight dependent manner. Most notably, we show that comb-shape POEGMA promotes significantly higher cellular uptake and exhibits less steric hindrance imposed on the conjugated biomolecule than PEG. Collectively, comb-shape POEGMA offers a versatile alternative to PEG for stealth polymer-biomolecule conjugation applications.Article Citation - WoS: 55Citation - Scopus: 61Insight Into Serum Protein Interactions With Functionalized Magnetic Nanoparticles in Biological Media(American Chemical Society, 2012) Wiogo, Hilda T. R.; Lim, May; Bulmuş, Volga; Gutie´rrez, Lucía; Woodward, Robert C.; Amal, RoseSurface modification with linear polymethacrylic acid (20 kDa), linear and branched polyethylenimine (25 kDa), and branched oligoethylenimine (800 Da) is commonly used to improve the function of magnetite nanoparticles (MNPs) in many biomedical applications. These polymers were shown herein to have different adsorption capacity and anticipated conformations on the surface of MNPs due to differences in their functional groups, architectures, and molecular weight. This in turn affects the interaction of MNPs surfaces with biological serum proteins (fetal bovine serum). MNPs coated with 25 kDa branched polyethylenimine were found to attract the highest amount of serum protein while MNPs coated with 20 kDa linear polymethacrylic acid adsorbed the least. The type and amount of protein adsorbed, and the surface conformation of the polymer was shown to affect the size stability of the MNPs in a model biological media (RPMI-1640). A moderate reduction in r 2 relaxivity was also observed for MNPs suspended in RPMI-1640 containing serum protein compared to the same particles suspended in water. However, the relaxivities following protein adsorption are still relatively high making the use of these polymer-coated MNPs as Magnetic Resonance Imaging (MRI) contrast agents feasible. This work shows that through judicious selection of functionalization polymers and elucidation of the factors governing the stabilization mechanism, the design of nanoparticles for applications in biologically relevant conditions can be improved. © 2012 American Chemical Society.