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Publication Metadata only [BMIM] [PF6] incorporation doubles CO2 selectivity of ZIF-8: elucidation of interactions and their consequences on performance(Amer Chemical Soc, 2016) N/A; N/A; N/A; N/A; N/A; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Kınık, Fatma Pelin; Altıntaş, Çiğdem; Balcı, Volkan; Koyutürk, Burak; Uzun, Alper; Keskin, Seda; Master Student; Researcher; PhD Student; Master Student; Faculty Member; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; N/A; 59917; 40548Experiments were combined with atomically detailed simulations and density functional theory (DFT) calculations to understand the effect of incorporation of an ionic liquid (IL), 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), into a metal organic framework (MOF with a zeolitic imidazolate framework), ZIF-8, on the CO2 separation performance. The interactions between [BMIM] [PF6] and ZIF-8 were examined in deep detail, and their consequences on CO2/CH4, CO2/N-2, and CH4/N-2 separation have been elucidated by using experimental measurements complemented by DFT calculations and atomically detailed simulations. Results suggest that IL-MOF interactions strongly affect the gas affinity of materials at low pressure, whereas available pore volume plays a key role for gas adsorption at high pressures. Direct interactions between IL and MOF lead to at least a doubling of CO2/CH4 and CO2/N-2 selectivities of ZIF-8. These results provide opportunities for rational design and development of IL-incorporated MOFs with exceptional selectivity for target gas separation applications.Publication Metadata only Adsorption and transport of CH4, CO2, H-2 mixtures in a bio-MOF material from molecular simulations(Amer Chemical Soc, 2011) N/A; N/A; Department of Chemical and Biological Engineering; Atcı, Erhan; Eruçar, İlknur; Keskin, Seda; Master Student; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 260094; 40548Accurate description of gas adsorption and diffusion in nanoporous materials is crucial in envisioning new materials for adsorption-based and membrane-based gas separations. This study provides the first information about the equilibrium and transport properties of different gas mixtures in a bio-metal organic framework (bio-MOF). Adsorption isotherms and self-diffusivity coefficients of CH4, CO2, H-2, and their binary mixtures in bio-MOF-11 were computed using grand canonical Monte Carlo and equilibrium molecular dynamics simulations. Results showed that bio-MOF-11 exhibits significantly higher adsorption selectivity for CO2 over CH4 and H-2 than the widely studied MOFs. Bio-MOF-11 outperforms several isoreticular MOFs, traditional zeolites, and zeolite imidazolate frameworks in membrane-based separations of CH4/H-2, CO2/CH4, and CO2/H-2 mixtures due to its high gas permeability and permeation selectivity. The methods used in this work will assess the potential of bio-MOFs in gas separations and accelerate development of new bio-MOFs for targeted applications by providing molecular insights into adsorption transport of gas mixtures.Publication Metadata only Adsorption, diffusion, and separation of CH4/H-2 mixtures in covalent organic frameworks: molecular simulations and theoretical predictions(amer Chemical Soc, 2012) N/A; Department of Chemical and Biological Engineering; Keskin, Seda; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 40548Grand canonical Monte Carlo and equilibrium molecular dynamics simulations were used to compute adsorption isotherms and self-diffusivities of CH4/H2 mixtures at various compositions in three representative covalent organic frameworks (COFs). Several properties of COFs such as adsorption selectivity, working capacity, diffusion selectivity, gas permeability, and membrane selectivity were evaluated and were compared with metal organic frameworks (MOFs), zeolites, zeolite imidazolate frameworks (ZIFs), and carbon nanotubes. Results showed that COF-6 outperforms traditional zeolites CHA, LTA, and ITQ-29 and MOFs IRMOF-1, CuBTT, and MOF-177 in adsorption-based CH4 selectivity. Membrane selectivities of COF-5, COF-6, and COF-10 were found to be higher than those of zeolites and similar to ZIFs and MOFs. Adsorption isotherms and diffusivities of CH4/H2 mixtures in the pores of COF-6 were computed using both atomically detailed simulations and theoretical correlations. Results showed that theoretical correlations based on single component adsorption and diffusion data can be used to accurately predict mixture adsorption and diffusion of gases in COFs.Publication Metadata only Aerogel-copper nanocomposites prepared using the adsorption of a polyfluorinated complex from supercritical CO2(Springer, 2012) Kostenko, Svetlana O.; Kurykin, Michael A.; Khrustalev, Victor N.; Khokhlov, Alexei R.; Zhang, Lichun; Aindow, Mark; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Bozbağ, Selmi Erim; Erkey, Can; Researcher; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; College of Engineering; N/A; 29633A supercritical deposition method has been used to synthesize aerogel-copper nanocomposites. Carbon, resorcinol-formaldehyde, and silica aerogels (CAs, RFAs, and SAs) were impregnated with a new polyfluorinated copper precursor (CuDI6), which has a high solubility in supercritical carbon dioxide (scCO(2)). Adsorption isotherms of CuDI6 onto various aerogels from scCO(2) were determined at 35 degrees C and 10.6 MPa using a batch method which is based on the measurement of the fluid phase concentration. The relative affinity between CuDI6 and different aerogels changed in the following order: CA > RFA > SA. The effect of temperature on the adsorption isotherms for the CuDI6-CO2-CA system was also studied at 35 and 55 degrees C and at a CO2 density of 736.1 kg/m(3). The CuDI6 uptake at a particular CuDI6 concentration increased with increasing temperature. Adsorbed CuDI6 was found to convert into Cu and Cu/Cu2O nanoparticles on the aerogel supports after chemical or thermal treatments at ambient pressure and at temperatures ranging from 200 to 400 degrees C.Publication Metadata only Aerogels for optofluidic waveguides(MDPI, 2017) Jonas, Alexandr; N/A; Department of Physics; Department of Chemical and Biological Engineering; Özbakır, Yaprak; Erkey, Can; Kiraz, Alper; PhD Student; Faculty Member; Faculty Member; Department of Physics; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Engineering; N/A; 29633; 22542Aerogels-solid materials keeping their internal structure of interconnected submicron-sized pores intact upon exchanging the pore liquid with a gas-were first synthesized in 1932 by Samuel Kistler. Overall, an aerogel is a special form of a highly porous material with a very low solid density and it is composed of individual nano-sized particles or fibers that are connected to form a three-dimensional network. The unique properties of these materials, such as open pores and high surface areas, are attributed to their high porosity and irregular solid structure, which can be tuned through proper selection of the preparation conditions. Moreover, their low refractive index makes them a remarkable solid-cladding material for developing liquid-core optofluidic waveguides based on total internal reflection of light. This paper is a comprehensive review of the literature on the use of aerogels for optofluidic waveguide applications. First, an overview of different types of aerogels and their physicochemical properties is presented. Subsequently, possible techniques to fabricate channels in aerogel monoliths are discussed and methods to make the channel surfaces hydrophobic are described in detail. Studies in the literature on the characterization of light propagation in liquid-filled channels within aerogel monoliths as well as their light-guiding characteristics are discussed. Finally, possible applications of aerogel-based optofluidic waveguides are described.Publication Metadata only An emerging family of hybrid nanomaterials: metal-organic framework/aerogel composites(Amer Chemical Soc, 2018) N/A; N/A; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; İnönü, Zeynep; Keskin, Seda; Erkey, Can; PhD student; Faculty Member; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 40548; 29633Metal-organic frameworks (MOFs) are crystalline nanoporous coordination polymers made of metal ions and organic linkers. Aerogels are highly nanoporous amorphous polymers that can be organic, inorganic, or hybrid. Both of these unique materials have been extensively investigated in many laboratories around the world for a wide range of applications ranging from separations to catalysis, resulting in thousands of published articles in a wide variety of journals. MOF/aerogel composites (MOFACs) are a new class of nanostructured materials that are attracting increasing attention because of their favorable properties. The combination of the micro- and mesoporosities of MOFs with the meso- and macroporosities of aerogels makes MOFACs hierarchically multimodal porous materials. With their high surface areas and combined morphological, mechanical, physicochemical, and functional properties of both MOFs and aerogels, MOFACs have demonstrated outstanding performances in various applications. Herein we provide an overview of the techniques used to synthesize MOFACs in various shapes such as monoliths or particles based on incorporation of MOFs into the porous networks of aerogels along with literature examples. The synthesis of aerogel-supported metals and metal oxides using MOFACs as precursors is also described. Several applications of these composites are reviewed, including adsorption, separation, catalysis, energy conversion, and storage devices such as batteries and supercapacitors. Future prospects in synthesis techniques and applications are provided to address opportunities and challenges in the field of MOFACs.Publication Metadata only Atomistic simulations for adsorption, diffusion, and separation of gas mixtures in zeolite imidazolate frameworks(Amer Chemical Soc, 2011) N/A; Department of Chemical and Biological Engineering; Keskin, Seda; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 40548Atomically detailed simulations were used to assess the performance of zeolite imidazolate frameworks (ZIFs) for separation of CH4/H-2, CO2/CH4, and CO2/H-2 mixtures to provide information for material selection in adsorbent and membrane designs. Adsorption isotherms and self-diffusivities of gas mixtures in ZIFs were computed using grand canonical Monte Carlo and equilibrium molecular dynamics simulations, respectively. Adsorption selectivity, diffusion selectivity, and permeation selectivity of ZIF membranes were calculated on the basis of the results of atomistic simulations. Selectivity and permeability of gases through ZIF membranes were compared to well-known zeolite membranes and metal organic framework (MOF) membranes. Results showed that ZIF-3 and ZIF-10 exhibit significantly higher adsorption and permeation selectivities for separation of all gas mixtures as compared to widely studied MOF membranes.Publication Metadata only Biosensing–drug delivery systems for in vivo applications(Elsevier, 2019) Erkoc, Pelin; N/A; N/A; Department of Chemical and Biological Engineering; Akolpoğlu, Mükrime Birgül; Bozüyük, Uğur; Kızılel, Seda; Master Student; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 28376Early detection of diseases can increase the efficiency of therapies. Recent advances in biosensor technology have led to the development of accurate and robust systems that can sense disease-dependent changes in analyte. These advancements have enabled faster diagnosis and treatment for various diseases. The invention of smart-responsive materials has opened new gates for next-generation biosensors, which can release the therapeutic payload upon environmental changes. These integrated systems provide increased therapeutic efficacy with reduced side effects, and a better perspective for biomedical applications. With further efforts, including comprehensive research and computational modeling, biosensing–drug delivery systems may become powerful tools for the treatment of chronic diseases.Publication Metadata only Computational screening of porous coordination networks for adsorption and membrane-based gas separations(Amer Chemical Soc, 2014) N/A; N/A; Department of Chemical and Biological Engineering; Öztürk, Tuğba Nur; Keskin, Seda; Master Student; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; College of Engineering; N/A; 40548Porous coordination networks (PCNs) are promising nanoporous materials in gas separation applications due to their tunable pore sizes, large surface areas, high porosities, and good thermal and mechanical stabilities. In this work, we investigated adsorption-based and membrane-based separation performances of 20 different PCNs for CH4/H-2, CO2/H-2, CO2/CH4, and CO2/N-2 mixtures using molecular simulations. Several PCNs were identified to show higher selectivity than traditional zeolites and polymers in membrane-based CO2 separations. We also developed simple models that can predict adsorption, diffusion, and permeation selectivities of PCNs for CH4/H-2 and CO2/H-2 mixtures based on the structural properties of materials such as pore volume, surface area, and pore diameter.Publication Metadata only Deep insight into PEGylation of bioadhesive chitosan nanoparticles: sensitivity study for the key parameters through artificial neural network model(Amer Chemical Soc, 2018) N/A; N/A; Department of Chemical and Biological Engineering; Bozüyük, Uğur; Doğan, Nihal Olcay; Kızılel, Seda; PhD Student; Master Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 28376lonically cross-linked chitosan nanoparticles have great potential in nanomedicine due to their tunable properties and cationic nature. However, low solubility of chitosan severely limits their potential clinical translation. PEGylation is a well-known method to increase solubility of chitosan and chitosan nanoparticles in neutral media; however, effect of PEG chain length and chitosan/PEG ratio on particle size and zeta potential of nanoparticles are not known. This study presents a systematic analysis of the effect of PEG chain length and chitosan/PEG ratio on size and zeta potential of nanoparticles. We prepared PEGylated chitosan chains prior to the nanoparticle synthesis with different PEG chain lengths and chitosan/PEG ratios. To precisely estimate the influence of critical parameters on size and zeta potential of nanoparticles, we both developed an artificial neural network (ANN) model and performed experimental characterization using the three independent input variables: (i) PEG chain length, (ii) chitosan/PEG ratio, and (iii) pH of solution. We studied the influence of PEG chain lengths of 2, 5, and 10 kDa and three different chitosan/PEG ratios (25 mg chitosan to 4, 12, and 20 mu moles of PEG) for the synthesis of chitosan nanoparticles within the pH range of 6.0-7.4. Artificial neural networks is a modeling tool used in nanomedicine to optimize and estimate inherent properties of the system. Inherent properties of a nanoparticle system such as size and zeta potential can be estimated based on previous experiment results, thus, nanoparticles with desired properties can be obtained using an ANN. With the ANN model, we were able to predict the size and zeta potential of nanoparticles under different experimental conditions and further confirmed the cell-nanoparticle adhesion behavior through experiments. Nanoparticle groups that had higher zeta potentials promoted adhesion of HEK293-T cells to nanoparticle-coated surfaces in cell culture medium, which was predicted through ANN model prior to experiments. Overall, this study comprehensively presents the PEGylation of chitosan, synthesis of PEGylated chitosan nanoparticles, utilizes ANN model as a tool to predict important properties such as size and zeta potential, and further captures the adhesion behavior of cells on surfaces prepared with these engineered nanoparticles.