Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 16Citation - Scopus: 15Ultrasound-Assisted Dopamine Polymerization: Rapid and Oxidizing Agent-Free Polydopamine Coatings on Membrane Surfaces(Royal Society of Chemistry, 2021) Cihanoğlu, Aydın; Schiffman, Jessica D.; Alsoy Altınkaya, SacideHerein, we report a controllable pathway to accelerate the polymerization kinetics of dopamine using ultrasound as a trigger. The use of ultrasound was demonstrated to dramatically accelerate the slow liquid phase reaction kinetics and increase the deposition rate of the polydopamine coating on the surface of polymeric membranes.Article Payne Cell Gravimetric Measurements in Polymer-Solvent Systems for Diffusion Coefficients and Isotherm Data(Wiley, 2021) Zielinski, John M.; Garcia, Armando R.; Alsoy Altınkaya, SacideThe discussion focuses on the application of a Payne cell to the measurement of diffusion and solubility coefficients in polymer/solvent systems. Payne cells have, thus far, been used exclusively to measure steady-state permeation rates of solvents. An analytical model has been developed to describe transient gravimetric sorption and desorption measurements performed with a Payne cell. The model has been validated by a complementary numerical simulation and has been applied to evaluate diffusion and solubility coefficients in two different toluene-silicone rubber systems. The data measured using the Payne cell are found to compare very well with diffusion coefficient and isotherm data measured by traditional gravimetric sorption experiments.Article Citation - WoS: 30Citation - Scopus: 44A Review on Computational Modeling Tools for Mof-Based Mixed Matrix Membranes(MDPI Multidisciplinary Digital Publishing Institute, 2019) Keskin, Seda; Alsoy Altınkaya, SacideComputational modeling of membrane materials is a rapidly growing field to investigate the properties of membrane materials beyond the limits of experimental techniques and to complement the experimental membrane studies by providing insights at the atomic-level. In this study, we first reviewed the fundamental approaches employed to describe the gas permeability/selectivity trade-off of polymer membranes and then addressed the great promise of mixed matrix membranes (MMMs) to overcome this trade-off. We then reviewed the current approaches for predicting the gas permeation through MMMs and specifically focused on MMMs composed of metal organic frameworks (MOFs). Computational tools such as atomically-detailed molecular simulations that can predict the gas separation performances of MOF-based MMMs prior to experimental investigation have been reviewed and the new computational methods that can provide information about the compatibility between the MOF and the polymer of the MMM have been discussed. We finally addressed the opportunities and challenges of using computational studies to analyze the barriers that must be overcome to advance the application of MOF-based membranes.Article Citation - WoS: 1Citation - Scopus: 1The Effect of Mass Transfer Resistance and Nonuniform Initial Solvent Concentration on Permeation Through Polymer Membranes(John Wiley and Sons Inc., 2018) Zielinski, John M.; Alsoy Altınkaya, SacideA numerical simulation model has been developed which enables one to examine the effects of surface mass transfer resistance on the evaluation of permeation (P*), diffusion (D), and solubility (S) coefficients from unsteady-state mass transfer experiments as well as the transmission rate. A complementary analytical expression has been developed which validates the numerical model and facilitates the evaluation of the concentration dependence of P*, D, and S from sequential step-change experiments, under experimental conditions when the surface mass transfer resistance can be neglected.Article Citation - WoS: 27Citation - Scopus: 37Nanofibrous Gelatine Scaffolds Integrated With Nerve Growth Factor-Loaded Alginate Microspheres for Brain Tissue Engineering(John Wiley and Sons Inc., 2018) Büyüköz, Melda; Erdal, Esra; Alsoy Altınkaya, SacideNeural regeneration research is designed in part to develop strategies for therapy after nerve damage due to injury or disease. In this study, a new gelatine-based biomimetic scaffold was fabricated for brain tissue engineering applications. A technique combining thermally induced phase separation and porogen leaching was used to create interconnected macropores and nanofibrous structure. To promote tissue regeneration processes, the scaffolds were integrated with nerve growth factor (NGF)-loaded alginate microspheres. The results showed that nanofibrous matrix could only be obtained when gelatine concentration was at least 7.5% (w/v). The scaffold with a modulus value (1.2 kPa) similar to that of brain tissue (0.5–1 kPa) was obtained by optimizing the heat treatment time, macropore size and gelatine concentration. The encapsulation efficiencies of NGF into 0.1% and 1% alginate microspheres were 85% and 100%, respectively. The release rate of NGF from the microspheres was controlled by the alginate concentration and the poly(L-lysine) coating. The immobilization of the microspheres in the scaffold reduced burst release and significantly extended the release period. The nanofibrous architecture and controlled release of NGF from the microspheres induced neurite extension of PC12 cells, demonstrating that the released NGF was in an active form. The results suggest that the scaffolds prepared in this study may have potential applications in brain tissue engineering due to topologic and mechanical properties similar to brain tissue and pore structure suitable for cell growth and differentiation.Article Citation - WoS: 13Citation - Scopus: 18Stimuli Responsive Polymer-Based Strategies for Polynucleotide Delivery(Cambridge University Press, 2017) Uz, Metin; Alsoy Altınkaya, Sacide; Mallapragada, Surya K.In recent years, stimuli responsive polymer based gene delivery vehicle design for cancer treatment and treatment of other genetic disorders has received extensive attention. Early studies focusing on DNA delivery have been facilitated by functional polymers and this area has seen further growth spurred by recent gene silencing strategies developed for small RNA [i.e., small interfering RNA (siRNA) or micro RNA (miRNA)] delivery. DNA and small RNAs possess analogous properties; however, their explicit differences define the specific challenges associated with the delivery route and the design of functional materials to overcome distinct challenges. Apart from classical gene delivery, the recent advances in genome editing have revealed the necessity of new delivery devices for genome editing tools. A system involving CRISPR (clustered, regularly interspaced, short palindromic repeats) and an endonuclease CRISPR-associated protein 9 (Cas9) coupled with a short, single-guide RNA (sgRNA) has emerged as a promising tool for genome editing along with functional delivery systems. For all these nucleic acid based treatments, the internal or external physiochemical changes in the biological tissue/cells play a major role in the design of stimuli responsive delivery materials for both in vitro and in vivo applications. This review emphasizes the recent advances in the use of pH, temperature, and redox potential-responsive polymers overcoming hurdles for delivery of gene and gene editing tools for both in vitro and in vivo applications. Specifically the chapter focuses on recently proposed delivery strategies, types of delivery systems, and polymer synthesis/modification methods. The recent advances in CRISPR/Cas9-sgRNA technology and delivery are also described in a separate section. The review ends with current clinical trials, concluding remarks, and future perspectives.Article Citation - WoS: 65Citation - Scopus: 72Effect of Peg Grafting Density and Hydrodynamic Volume on Gold Nanoparticle-Cell Interactions: an Investigation on Cell Cycle, Apoptosis, and Dna Damage(American Chemical Society, 2016) Uz, Metin; Bulmuş, Volga; Alsoy Altınkaya, SacideIn this study, interactions of polyethylene glycol (PEG)-coated gold nanoparticles (AuNPs) with cells were investigated with particular focus on the relationship between the PEG layer properties (conformation, grafting density, and hydrodynamic volume) and cell cycle arrest, apoptosis, and DNA damage. Steric hindrance and PEG hydrodynamic volume controlled the protein adsorption, whereas the AuNP core size and PEG hydrodynamic volume were primary factors for cell uptake and viability. At all PEG grafting densities, the particles caused significant cell cycle arrest and DNA damage against CaCo2 and PC3 cells without apoptosis. However, at a particular PEG grafting density (∼0.65 chains/nm2), none of these severe damages were observed on 3T3 cells indicating discriminating behavior of the healthy (3T3) and cancer (PC3 and CaCo2) cells. It was concluded that the PEG grafting density and hydrodynamic volume, tuned with the PEG concentration and AuNP size, played an important role in particle-cell interactions.Article Citation - WoS: 44Citation - Scopus: 44Chitosan-Polyoxometalate Nanocomposites: Synthesis, Characterization and Application as Antimicrobial Agents(Springer Verlag, 2014) Fiorani, Giulia; Saoncella, Omar; Kaner, P.; Alsoy Altınkaya, Sacide; Figoli, Alberto; Bonchio, Marcella; Carraro, MauroPolyoxometalates (POMs) were used, together with chitosan (CS), to obtain hybrid nanoaggregates. Three representative POMs were efficiently assembled into nanoparticles of few hundred nm diameter, featuring entangled ribbons substructure. In order to establish suitable preparation and stability conditions, the assemblies were characterized in solution by UV-Vis spectroscopy, dynamic light scattering and ζ-potential. The nanoparticles were tested against E. coli (106 CFU/ml) in aqueous solution, showing a synergic activity of the heteropolyacid H5PMo10V2O40 and CS. For such components, a highly porous and antibacterial film was obtained upon lyophilisation of the colloidal mixture.Article Citation - WoS: 29Citation - Scopus: 33Surface Modification of Polysulfone Based Hemodialysis Membranes With Layer by Layer Self Assembly of Polyethyleneimine/Alginate-heparin: a Simple Polyelectrolyte Blend Approach for Heparin Immobilization(Springer Verlag, 2013) Yaşar Mahlıçlı, Filiz; Alsoy Altınkaya, SacideThis study intends to improve blood compatibility of polysulfone (PSF) membranes by generating a nonthrombogenic surface through heparin immobilization. To achieve this task, the support membrane prepared from a blend of PSF and sulfonated polysulfone (SPSF) was modified with layer by layer (LBL) deposition of polyethyleneimine (PEI) and alginate (ALG) and heparin blended with ALG was immobilized only on the outermost surface of the LBL assembly. The results have shown that the adsorption of human plasma proteins and platelet activation on the LBL modified membranes decreased significantly compared with the unmodified PSF and PSF-SPSF blend membranes. Furthermore, blending ALG with a small amount of heparin remarkably prolonged the APTT values of heparin free PEI/ALG coated membranes. It is envisaged that the use of a blend of HEP and ALG only in the terminating layer of the LBL assembly can be an economical and alternative modification technique to create nonthrombogenic surfaces.Article Citation - WoS: 9Citation - Scopus: 8Measurement of Ternary Polymer/Solvent Equilibrium Data by Vapor-Phase Infrared Spectroscopy(Elsevier Ltd., 2009) Yürekli, Yılmaz; Alsoy Altınkaya, SacideVapor-liquid equilibrium (VLE) data for binary toluene/PVAC, methanol/PVAC and ternary toluene/methanol/PVAC systems have been measured at 100 °C by using vapor-phase infrared spectroscopy. Binary data have been compared with literature data measured by different experimental techniques and agreement between our measurements and others was found to be good. The ternary VLE data indicate that the solubility of methanol in PVAC is not influenced by the presence of toluene, while the solubility of toluene is lowered due to presence of methanol. To predict ternary VLE data, the Entropic free volume and Kannan free volume models and the Flory-Huggins theory were used. The predictive abilities of Flory-Huggins theory and the Kannan free volume model are similar and better than that of the Entropic free volume model.