Chemical Engineering / Kimya Mühendisliği

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Citation - WoS: 11
Citation - Scopus: 14
3D Bioprinting of mouse pre-osteoblasts and human MSCs using bioinks consisting of gelatin and decellularized bone particles
(Iop Publishing Ltd, 2024) Kara, Aylin; Distler, Thomas; Akkineni, Ashwini Rahul; Tihminlioglu, Funda; Gelinsky, Michael; Boccaccini, Aldo R.
One of the key challenges in biofabrication applications is to obtain bioinks that provide a balance between printability, shape fidelity, cell viability, and tissue maturation. Decellularization methods allow the extraction of natural extracellular matrix, preserving tissue-specific matrix proteins. However, the critical challenge in bone decellularization is to preserve both organic (collagen, proteoglycans) and inorganic components (hydroxyapatite) to maintain the natural composition and functionality of bone. Besides, there is a need to investigate the effects of decellularized bone (DB) particles as a tissue-based additive in bioink formulation to develop functional bioinks. Here we evaluated the effect of incorporating DB particles of different sizes (<= 45 and <= 100 mu m) and concentrations (1%, 5%, 10% (wt %)) into bioink formulations containing gelatin (GEL) and pre-osteoblasts (MC3T3-E1) or human mesenchymal stem cells (hTERT-MSCs). In addition, we propose a minimalistic bioink formulation using GEL, DB particles and cells with an easy preparation process resulting in a high cell viability. The printability properties of the inks were evaluated. Additionally, rheological properties were determined with shear thinning and thixotropy tests. The bioprinted constructs were cultured for 28 days. The viability, proliferation, and osteogenic differentiation capacity of cells were evaluated using biochemical assays and fluorescence microscopy. The incorporation of DB particles enhanced cell proliferation and osteogenic differentiation capacity which might be due to the natural collagen and hydroxyapatite content of DB particles. Alkaline phosphatase activity is increased significantly by using DB particles, notably, without an osteogenic induction of the cells. Moreover, fluorescence images display pronounced cell-material interaction and cell attachment inside the constructs. With these promising results, the present minimalistic bioink formulation is envisioned as a potential candidate for bone tissue engineering as a clinically translatable material with straightforward preparation and high cell activity.
Citation - WoS: 48
Citation - Scopus: 54
3d Printed Gelatin/Decellularized Bone Composite Scaffolds for Bone Tissue Engineering: Fabrication, Characterization and Cytocompatibility Study
(Elsevier, 2022-06) Kara, Aylin; Distler, Thomas; Polley, Christian; Schneidereit, Dominik; Seitz, Hermann; Friedrich, Oliver; Tıhmınlıoğlu, Funda; Boccaccini, Aldo R
Three-dimensional (3D) printing technology enables the design of personalized scaffolds with tunable pore size and composition. Combining decellularization and 3D printing techniques provides the opportunity to fabricate scaffolds with high potential to mimic native tissue. The aim of this study is to produce novel decellularized bone extracellular matrix (dbECM)-reinforced composite-scaffold that can be used as a biomaterial for bone tissue engineering. Decellularized bone particles (dbPTs, ∼100 μm diameter) were obtained from rabbit femur and used as a reinforcement agent by mixing with gelatin (GEL) in different concentrations. 3D scaffolds were fabricated by using an extrusion-based bioprinter and crosslinking with microbial transglutaminase (mTG) enzyme, followed by freeze-drying to obtain porous structures. Fabricated 3D scaffolds were characterized morphologically, mechanically, and chemically. Furthermore, MC3T3-E1 mouse pre-osteoblast cells were seeded on the dbPTs reinforced GEL scaffolds (GEL/dbPTs) and cultured for 21 days to assess cytocompatibility and cell attachment. We demonstrate the 3D-printability of dbPTs-reinforced GEL hydrogels and the achievement of homogenous distribution of the dbPTs in the whole scaffold structure, as well as bioactivity and cytocompatibility of GEL/dbPTs scaffolds. It was shown that Young's modulus and degradation rate of scaffolds were enhanced with increasing dbPTs content. Multiphoton microscopy imaging displayed the interaction of cells with dbPTs, indicating attachment and proliferation of cells around the particles as well as into the GEL-particle hydrogels. Our results demonstrate that GEL/dbPTs hydrogel formulations have potential for bone tissue engineering.
Acid-Catalyzed Degradation of Biomass With Hydrothermal Electrolysis for the Production of Value-Added Chemicals
(American Chemical Society, 2014) Yüksel, Aslı; Yüksel Özşen, Aslı
[No abstract available]
Citation - WoS: 22
Citation - Scopus: 23
Acidic Sites in Beta Zeolites in Dependence of the Preparation Methods
(Elsevier Ltd., 2004-06) Dimitrova, R.; Gündüz, Gönül; Dimitrov, L.; Tsoncheva, T.; Yılmaz, Selahattin; Urquieta-González, Ernesto Antonio
Beta zeolites synthesized by different methods are compared in their structure peculiarities and acidic properties by nitrogen physisorption, IR-KBr, pyridine sorption-desorption and thermoprogrammed desorption of ammonia. It is found that mesopores could be obtained in beta zeolites with the change of the activation procedure. Methanol conversion to dimethyl ether and hydrocarbons is used as a test reaction for understanding of the acid center function.
Citation - WoS: 21
Citation - Scopus: 23
Activated Carbon Adsorption of Fuel Oxygenates Mtbe and Etbe From Water
(Springer Verlag, 2009-11) İnal, Fikret; Yetgin, Senem; Aksu, Gülsüm T.; Şimşek, Selvi; Sofuoğlu, Aysun; Sofuoğlu, Sait Cemil
The aqueous phase adsorption of fuel oxygenates methyl tertiary butyl ether (MTBE) and ethyl tertiary butyl ether (ETBE) onto commercially available granular activated carbon (GAC; Norit GAC 1240) was investigated in a batch system at 27°C. The oxygenate concentrations were determined by headspace gas chromatography/mass spectrometry analyses. The experimental data were used with four two-parameter isotherm models (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) and two kinetic models (pseudo first-order and pseudo second-order) to determine equilibrium and kinetic parameters. Considering the correlation coefficient and root mean square error, Dubinin-Radushkevich isotherm showed better fit with the equilibrium data for MTBE. However, the performances of Langmuir and Dubinin-Radushkevich models were comparable for ETBE. The adsorption capacities were calculated as 5.50 and 6.92 mg/g for MTBE and ETBE, respectively, at an equilibrium solution concentration of 1 mg/L using Dubinin-Radushkevich isotherm. The differences between the model predictions and experimental data were similar for the pseudo first-order and pseudo second-order kinetic models. Gibbs free-energy changes of adsorption were found to be -22.59 and -28.55 kJ/mol for MTBE-GAC and ETBE-GAC systems, respectively, under the experimental conditions studied.
Citation - WoS: 7
Citation - Scopus: 8
Acylation of 2-Methoxynaphthalene Over Ion-Exchanged Ss-Zeolite
(Elsevier Ltd., 2002) Kantarlı, İsmail Cem; Artok, Levent; Bulut, Hatice; Yılmaz, Selahattin; Ülkü, Semra
Friedel-Crafts acylation of 2-Methoxynaphthalene was carried out over various ion-exchanged β zeolites (Mn+β, where Mn+: In3+, Zn2+, Al3+, Fe3+, La3+) with various anhydride (acetic, propionic and benzoic anhydrides), or acyl chloride (acetyl, propionyl and benzoyl chlorides) acylating reagents. The results suggested that selectivity towards the 6-substituted products was higher with the larger size anhydrides, propionic and benzoic anhydrides. The metal cation type within the zeolite significantly influenced the extent of conversion and product distribution. That La3+ exchanged zeolite displayed higher selectivity for the 6-position acylated product with anhydrides ascribed mainly to narrowing of channels by the presence of La(OH)2+ ions that leave no room for the formation of more bulky isomeric forms and to enhanced Bronsted acidity of the zeolite. With acyl chlorides, the recovery of ketone products was found to be remarkably low. 1-Acyl-2-methoxynaphthalenes actively underwent deacylation when acyl chlorides were used as the acylation reagent.
Citation - WoS: 3
Citation - Scopus: 5
Adsorption Characteristics of Lead-, Barium- and Hydrogen-Rich Clinoptilolite Mineral
(SAGE Publications Inc., 2003) Çakıcıoğlu Özkan, Seher Fehime; Ülkü, Semra
The carbon dioxide and water vapour adsorption properties of local clinoptilolite-rich material, both as the original and as lead-, barium- and hydrogen-rich forms, were examined. The lead- and barium-rich forms were prepared by treatment of the original clinoptilolite with Pb(NO3)2 and BaCl2 respectively, while the hydrogen-rich form was prepared by NH4Cl and heat treatment. Water and CO2 adsorption experiments were conducted in a volumetric system under static conditions, with low-pressure adsorption data being used for the characterization of the natural, Pb-rich, Ba-rich and H-rich clinoptilolite samples. Although the existence of barium-exchange was not noted, an appreciable decrease in CO2 adsorption was observed with the Pb-rich and H-rich forms due to a decrease in the electrostatic interaction between the surface and the adsorbate. Application of the Dubinin-Astakhov equation to the water adsorption data established the existence of micropores of different sizes that exhibited different adsorption mechanisms.
Citation - WoS: 4
Citation - Scopus: 4
Adsorption Kinetics of Methane Reformer Off-Gases on Aluminum Based Metal-Organic Framework
(Elsevier Ltd., 2020) Angı, Deniz; Çakıcıoğlu Özkan, Seher Fehime
Solvothermal synthesis of aluminum based metal-organic frameworks (MIL-53(Al)s) were conducted by considering the effects of crystallization and activation temperatures, and the solvent at purification step. Adsorption kinetics of Steam Methane Reformer off gas components at 34, 70 and 100 °C temperatures was measured by using ZLC method. Henry constant decreases as diffusion coefficient of the gases increases with increasing temperature; It was determined that the CO gas has the highest activation energy. Adsorption kinetics of gases were controlled with electrostatic interaction. © 2020 Hydrogen Energy Publications LLC
Citation - WoS: 21
Citation - Scopus: 23
Adsorption of Anionic Polyelectrolyte and Comb Polymers Onto Lead Magnesium Niobate
(Elsevier Ltd., 2008-03) Şakar-Deliormanlı, Aylin; Çelik, Erdal; Polat, Mehmet
This paper presents the results concerning the adsorption mechanism of polyacrylic acid (PAA) and polyacrylic acid/polyethylene oxide (PAA/PEO) comb polymer onto lead magnesium niobate (PMN) powders. In the study adsorption behavior of PAA and PAA/PEO onto PMN surface were determined in aqueous solutions and the influence of pH and ionic strength was investigated. Results showed that adsorption of PAA or PAA/PEO increased with decreasing pH of the suspensions. The increase in the ionic strength or the presence of divalent cations caused an increase in the adsorption of both polyelectrolytes. It was observed that the adsorption reaches a maximum when PAA is fully complexed in solution. On the other hand, the increase in the adsorption of PAA/PEO onto PMN in the presence of monovalent or divalent salt was attributed to the decrease in the electrostatic forces rather than complex formation with the divalent metal ions in solution. Turbidity measurements showed that there is no complex formation between the divalent metal ions and PAA/PEO comb polymers due to shielding effect of the PEO teeth.
Citation - WoS: 3
Citation - Scopus: 2
Adsorption of No in Clinoptilolite-Rich Zeolitic Mineral by Concentration Pulse Chromatography Method
(Elsevier Ltd., 2016) Narin, Güler; Ülkü, Semra
The equilibrium and kinetic parameters for NO adsorption in a clinoptilolite-rich natural zeolitic material from Turkey were determined using the concentration pulse chromatography method. Under the experimental conditions (carrier gas velocities and adsorption temperatures) the micropore diffusion resistance was found to be the mass transfer controlling step. Matching the first moment of the response peaks to the mathematical model the Henry's Law constants and heat of adsorption at zero loading were determined. The axial dispersion, external film, macropore and micropore diffusion coefficients, and activation energy for diffusion of NO in the micropores were calculated from the analysis of the second moments of the response peaks. For successive NO pulses without regeneration between the pulses, the retention times of the response peaks decreased and peak areas increased with the injection number indicating irreversible adsorption. The reversibly adsorbed NO could be desorbed by purging with an inert gas at the adsorption pressure and temperature. Temperature programmed desorption profile obtained by heating the NO saturated adsorbent to 400 °C under inert flow revealed presence of multiple irreversibly adsorbed species in NZ with different thermal stabilities. Desorption of these species was not achieved during the heating up to 400 °C which makes the natural zeolitic materıal suitable for NO storage rather than for cyclic adsorptive separation processes.
Citation - WoS: 70
Citation - Scopus: 87
Adsorption of Olive Leaf (olea Europaea L.) Antioxidants on Silk Fibroin
(American Chemical Society, 2007) Bayçın, Deniz; Altıok, Evren; Ülkü, Semra; Bayraktar, Oğuz
The adsorption isotherms of oleuropein and rutin were evaluated at different temperatures, pH values, and solid/liquid ratios. The experimental data of adsorption isotherms were well fitted to a Langmuir model. The maximum adsorption capacities were determined as 108 mg of oleuropein/g of silk fibroin and 21 mg of rutin/g of silk fibroin. After adsorption of oleuropein and rutin, the antioxidant capacity of silk fibroin increased from 1.93 to 3.61 mmol of TEAC/g. Silk fibroin also gained antimicrobial activity against Staphylococcus aureus and Klebsiella pneumoniae after adsorption of olive leaf antioxidants. In a desorption process, 81% of rutin and 85% of oleuropein were removed from the adsorbent surface in 70% aqueous ethanol solution. Consequently, silk fibroin was found to be a promising biomaterial for the production of functional food or dietary supplements and for the purification of oleuropein and rutin from olive leaf extracts.
Advances in Nanocomposite Membranes for CO2 Removal
(Elsevier, 2024) Marpani,F.; Othman,N.H.; Alias,N.H.; Mat Shayuti,M.S.; Alsoy Altınkaya, Sacide
Nanocomposite membranes have emerged as a promising solution for efficient carbon dioxide (CO2) removal in gas separation processes. These membranes combine polymeric matrices with inorganic nanofillers to synergize the excellent separation performance of inorganic materials with the mechanical stability of polymers. The choice of nanofillers, such as porous and nonporous materials, significantly influences the gas permeability and selectivity of the resulting nanocomposite membranes. Porous fillers with interstitial channels and large surface areas are found to selectively adsorb CO2, enhancing membrane separation performance. On the other hand, nonporous fillers alter the polymer chain orientation, influencing gas separation differently. The 1D, 2D, and 3D morphologies of nanofillers offer unique properties in terms of surface-to-volume ratio, permeability, and selectivity. The fabrication of nanocomposite membranes also plays a crucial role, and advances in materials and manufacturing techniques have enabled the design of high-performing membranes. Asymmetric and symmetric configurations have been explored to optimize separation efficiency. Nevertheless, challenges such as aging, compaction, and swelling need to be addressed to ensure the long-term stability of nanocomposite membranes. Future research should focus on developing advanced theoretical models to better predict gas permeation behaviors in these membranes. Overall, nanocomposite membranes offer a promising avenue for efficient CO2 removal, contributing to sustainable environmental practices and energy production. © 2024 Elsevier Ltd. All rights reserved.
Citation - WoS: 64
Citation - Scopus: 74
Air and Seawater Pollution and Air–sea Gas Exchange of Persistent Toxic Substances in the Aegean Sea: Spatial Trends of Pahs, Pcbs, Ocps and Pbdes
(Springer Verlag, 2015-08) Lammel, Gerhard; Audy, Ondrej; Besis, Athanasios; Efstathiou, Christos; Eleftheriadis, Kostas; Kohoutek, Jiri; Kukucka, Petr; Mulder, Marie D.; Pribylova, Petra; Prokes, Roman; Rusina, Tatsiana P.; Samara, Constantini; Sofuoğlu, Aysun; Sofuoğlu, Sait Cemil; Taşdemir, Yücel; Vassilatou, Vassiliki; Voutsa, Dimitra; Vrana, Branislav
Near-ground air (26 substances) and surface seawater (55 substances) concentrations of persistent toxic substances (PTS) were determined in July 2012 in a coordinated and coherent way around the Aegean Sea based on passive air (10 sites in 5 areas) and water (4 sites in 2 areas) sampling. The direction of air–sea exchange was determined for 18 PTS. Identical samplers were deployed at all sites and were analysed at one laboratory. hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs) as well as dichlorodiphenyltrichloroethane (DDT) and its degradation products are evenly distributed in the air of the whole region. Air concentrations of p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE) and o,p′-DDT and seawater concentrations of p,p′-DDE and p,p′-DDD were elevated in Thermaikos Gulf, northwestern Aegean Sea. The polychlorinated biphenyl (PCB) congener pattern in air is identical throughout the region, while polybrominated diphenylether (PBDE)patterns are obviously dissimilar between Greece and Turkey. Various pollutants, polycyclic aromatic hydrocarbons (PAHs), PCBs, DDE, and penta- and hexachlorobenzene are found close to phase equilibrium or net-volatilisational (upward flux), similarly at a remote site (on Crete) and in the more polluted Thermaikos Gulf. The results suggest that effective passive air sampling volumes may not be representative across sites when PAHs significantly partitioning to the particulate phase are included.
Citation - WoS: 67
Citation - Scopus: 75
Air-Water Exchange of Polychlorinated Biphenyls (pcbs) and Organochlorine Pesticides (ocps) at a Coastal Site in Izmir Bay, Turkey
(Elsevier Ltd., 2008-02) Odabaşı, Mustafa; Çetin, Banu; Demircioğlu, Eylem; Sofuoğlu, Aysun
The air-water exchange of polychlorinated biphenyl (PCB) and organochlorine pesticides (OCPs) were investigated using paired air-water samples (n = 16) collected in July and February-March, 2005 from Guzelyali Port in Izmir Bay, Turkey. Atmospheric PCBs and OCPs were mainly in gas-phase in both periods. However, their dissolved and particle-phase water concentrations were comparable. For PCBs, 3 and 4-Cl congeners were dominant while chlorpyrifos, endosulfans and HCHs were the most abundant OCPs for all samples. Especially in summer, calculated net gas-exchange PCB fluxes were mainly volatilization from the water ranging from - 0.2 (volatilization, PCB-101) to - 30.0 (volatilization, PCB-31) ng m- 2 day- 1. For OCPs, net flux ranged from - 0.03 (volatilization, cis-nonachlor) to 1568 (deposition, endosulfan I) ng m- 2 day- 1 and they have seasonal variations with generally deposition in winter and volatilization in summer. However, endosulfan I, II, endosulfan sulfate, α- and γ-HCH deposited in both periods. The calculated residence times of PCBs and OCPs in the water column indicated that the gas-exchange in the Bay is at least as or a more important mechanism than advection. Annual gaseous absorption and volatilization fluxes were calculated and were used along with the estimated dry deposition fluxes and wet deposition fluxes measured recently at a suburban site in Izmir to determine the relative contributions of different atmospheric mechanisms to the pollutant inventory of the Bay water column. Results suggested that the relative contributions of all studied mechanisms to the water column PCB and OCP inventories were significant.
Citation - WoS: 38
Citation - Scopus: 45
Alpha-Pinene Isomerization on Acid-Treated Clays
(Elsevier Ltd., 2002-01) Beşün, Nurgün; Özkan, Fehime; Gündüz, Gönül
Liquid phase isomerization of α-pinene was studied over a number of differently pre-treated montmorillonite clays. The effects of the acid pre-treatment parameters (acid-to-clay ratio (A/C), water-to-acid ratio (W/A), temperature and pre-treatment time) on the product distribution were investigated. It was observed that the pre-treatment with acid improved the catalytic activity of that catalyst which was activated at 200 °C for 4 h at A/C ratios between 0.2 and 0.4. Alpha-pinene consumption was very small over the catalysts prepared with an A/C ratio of 0.8. Characterization studies that were done by nitrogen and water vapor adsorption experiments and by IR measurements showed that catalysts with high differential pore volumes for pores around 2 nm and homogenous mesopore distributions and with low dealumination degrees were good catalysts for the production of camphene. Catalysts having heterogeneous mesoporosity were found to be the preferable ones for limonene production.
Citation - WoS: 5
Citation - Scopus: 7
Alumina/Water Suspensions in the Presence of Peo-Ppo Triblock Copolymers
(Elsevier Ltd., 2004-09) Şakar Deliormanlı, Aylin; Polat, Hürriyet; Çiftçioğlu, Muhsin
The aim of this study was to investigate the stability and dispersion behaviour of aqueous alumina suspensions in the presence of polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) type triblock copolymers. For this purpose alumina suspensions at various solids loadings were prepared using four different methods. These are: Method I: powder and water were stirred only; Method II: powder and water were stirred and ultrasonic treatment was applied; Method III: powder and water were stirred in the presence of block copolymers; Method IV: powder and water were stirred and ultrasonic treatment was applied in the presence of block copolymers. These suspensions were characterized by means of rheological measurements. Sedimentation and turbidity measurements were also conducted to support these results and to investigate the stability of these systems for longer times. Surface tension measurements were performed to investigate the adsorption behaviour of block copolymers onto alumina surface. It was found that the use of PEO-PPO-PEO type triblock copolymers improved the dispersion behaviour of aqueous alumina suspensions in the presence of ultrasonic treatment at low solids loadings. However their effect was not significant at high solids loadings and without ultrasonic treatment.
Citation - Scopus: 5
Aluminium-Coated Polymer Films as Infrared Light Shields for Food Packing
(Apple Academic Press, 2014) Hamrang, Abbas; Balköse, Devrim; Zaikov, Gennadij Efremovich; Haghi, A. K.
This book covers a broad range of polymeric materials and provides industry professionals and researchers in polymer science and technology with a single, comprehensive book summarizing all aspects involved in the functional materials production chain. This volume presents the latest developments and trends in advanced polymer materials and structures. It discusses the developments of advanced polymers and respective tools to characterize and predict the material properties and behavior. This book has an important role in advancing polymer materials in macro and nanoscale. Its aim is to provide original, theoretical, and important experimental results that use non-routine methodologies. It also includes chapters on novel applications of more familiar experimental techniques and analyses of composite problems that indicate the need for new experimental approaches. This new book: • Provides a collection of articles that highlight some important areas of current interest in key polymeric materials and technology. • Gives an up-to-date and thorough exposition of the present state of the art of key polymeric materials and technology. • Describes the types of techniques now available to the engineers and technicians and discusses their capabilities, limitations, and applications. • Provides a balance between materials science and chemical aspects, basic and applied research. • Focuses on topics with more advanced methods. • Emphasizes precise mathematical development and actual experimental details. • Explains modification methods for changing of different materials properties. © 2020 Elsevier B.V., All rights reserved.
Citation - WoS: 34
Citation - Scopus: 35
Ammonium sorption by Gördes clinoptilolite rich mineral specimen
(Elsevier Ltd., 2011-12) Cansever Erdoğan, Beyhan; Ülkü, Semra
Experimental and theoretical works were performed for the estimation of the effects of pH, initial concentration, agitation speed, particle size and temperature on the ammonium sorption by local clinoptilolite rich mineral specimen. The kinetic sorption data were analyzed using external mass transfer, intraparticle diffusion, pseudo first and second order kinetic models. Diffusion model results revealed that external film diffusion dominated at the very early stages of sorption process and then it was overcome by intraparticle diffusion. Pseudo-second order kinetic model correlated with the experimental data better than the pseudo first order kinetic model. Sorption isotherm model results indicated that the Langmuir isotherm fitted well to the experimental data. Thermodynamic parameters Gibbs energy change (δG), enthalpy change (δH) and entropy change (δS) were calculated. It was shown that the sorption process was exothermic and spontaneous. The value of the activation energy suggested that ammonium sorption by the clinoptilolite rich mineral specimen is likely due to physical interactions between the sorbent and the sorbate. Analysis of the cation exchange results revealed that ion exchange mechanism was not the only step which was effective in ammonium sorption.
Citation - WoS: 10
Citation - Scopus: 12
Analysis of Dilution Induced Disintegration of Micellar Drug Carriers in the Presence of Inter and Intra Micellar Species
(Elsevier, 2020) Polat, Hürriyet; Kutluay, Gülistan; Polat, Mehmet
Micelles of self-assembling polymeric surfactant molecules are promising nanoscopic carriers for lipophilic and toxic drugs, genes, and imaging molecules. Though it is a must for successful transport, ensuring micelle integrity is a challenge during intravenous injection where micelles must endure abrupt dilutional effects and encounters with native molecules. Therefore, direct observational evidence of how micelles behave during dilution is valuable in manipulating the designs of these carriers for a succesful drug delivery. Morphology and stability of the barren and a drug-loaded (lipophilic probucol) micelles of a polymeric surfactant (Pluronic® P123) were monitored during systematic re-dilution in distilled water and simulated body fluid in the presence of a model protein (bovine serum albumin). It was observed through surface tension, dynamic light scattering, laser velocimetry, transmission scanning and transmission electron microscopy, and atomic force microscopy analyses that the micelles disintegrated to various degrees in all cases upon dilution. The results indicate that dilution effects must be taken into account in designing micellar drug carriers. The assistance of some other means of protection such as encapsulation should be considered for ensuring micelle integrity within the bloodstream. © 2020 Elsevier B.V.
Citation - WoS: 23
Citation - Scopus: 24
Analytical Solution of Poisson-Boltzmann Equation for Interacting Plates of Arbitrary Potentials and Same Sign
(Elsevier Ltd., 2010-01) Polat, Mehmet; Polat, Hürriyet
Efficient calculation of electrostatic interactions in colloidal systems is becoming more important with the advent of such probing techniques as atomic force microscopy. Such practice requires solving the nonlinear Poisson-Boltzmann equation (PBE). Unfortunately, explicit analytical solutions are available only for the weakly charged surfaces. Analysis of arbitrarily charged surfaces is possible only through cumbersome numerical computations. A compact analytical solution of the one-dimensional PBE is presented for two plates interacting in symmetrical electrolytes. The plates can have arbitrary surface potentials at infinite separation as long they have the same sign. Such a condition covers a majority of the colloidal systems encountered. The solution leads to a simple relationship which permits determination of surface potentials, surface charge densities, and electrostatic pressures as a function of plate separation H for different charging scenarios. An analytical expression is also presented for the potential profile between the plates for a given separation. Comparison of these potential profiles with those obtained by numerical analysis shows the validity of the proposed solution. © 2009 Elsevier Inc. All rights reserved.

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