Researcher:
Aydın, Derya

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PhD Student

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Derya

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Aydın

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Aydın, Derya

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2014 - 20189

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Now showing 1 - 9 of 9
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    Design of stimuli-responsive drug delivery hydrogels synthesis and applications
    (Crc Press-Taylor and Francis Group, 2017) N/A; N/A; Department of Chemical and Biological Engineering; Aydın, Derya; Alipour, Mohammad; Kızılel, Seda; PhD 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; 28376
    Stimuli-responsive hydrogels have become popular in medicine and Polymer science as useful 'smart' devices due to their various properties such as overall biocompatibility, high drug loading capacity, and controlled molecule delivery. By tuning the polymer side chains and degree of crosslinking, these gels may exhibit swelling/shrinking behaviour in response to environmental stimuli such as light, pH, chemicals, temperature, mechanical strain, and electrical field. Sensitivity of these hydrogels enables precise control over fundamental material properties such as physical structure, porosity, swelling behaviour, mechanical strength and drug permeability. Temperature and pH alterations are examples of physiological deviations that are commonly considered for the design of responsive hydrogels, specifically for site-specific controlled drug delivery. a class of hydrogels known as multi-responsive hydrogels can respond to more than one stimuli which make them tunable and controllable with improved biomimetic properties well-suited for controlled and site specific drug delivery. Despite all these attractive properties of stimuli-responsive hydrogels, slow response time may cause some limitations in practical applications. Reduced hydrogel thickness may decrease the response time of the gel to a stimulus; however, this may lead to mechanically fragile hydrogel structures. therefore, practical applications need significant improvement in hydrogel design to improve response time considering mechanical properties, biocompatibility, and biodegradability. This chapter highlights recent progress in the field of stimuli-responsive hydrogels, focusing primarily on drug delivery vehicles.
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    Water-in-water emulsion based synthesis of hydrogel nanospheres with tunable release kinetics
    (Springer, 2017) N/A; Department of Chemical and Biological Engineering; Aydın, Derya; Kızılel, Seda; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 28376
    Poly(ethylene glycol) (PEG) micro/nanospheres have several unique advantages as polymer based drug delivery systems (DDS) such as tunable size, large surface area to volume ratio, and colloidal stability. Emulsification is one of the widely used methods for facile synthesis of micro/nanospheres. Two-phase aqueous system based on polymer-polymer immiscibility is a novel approach for preparation of water-in-water (w/w) emulsions. This method is promising for the synthesis of PEG micro/nanospheres for biological systems, since the emulsion is aqueous and do not require organic solvents or surfactants. Here, we report the synthesis of nano-scale PEG hydrogel particles using w/w emulsions using phase separation of dextran and PEG prepolymer. Dynamic light scattering (DLS) and scaning electron microscopy (SEM) results demonstrated that nano-scale hydrogel spheres could be obtained with this approach. We investigated the release kinetics of a model drug, pregabalin (PGB) from PEG nanospheres and demonstrated the influence of polymerization conditions on loading and release of the drug as well as the morphology and size distribution of PEG nanospheres. the experimental drug release data was fitted to a stretched exponential function which suggested high correlation with experimental results to predict half-time and drug release rates from the model equation. the biocompatibility of nanospheres on human dermal fibroblasts using cell-survival assay suggested that PEG nanospheres with altered concentrations are non-toxic, and can be considered for controlled drug/molecule delivery.
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    Identification and characterization of small molecule inhibitors targeting dna polymerase gamma for the treatment of cancers deficient in mismatch repair
    (Wiley-Blackwell, 2015) Pamukcu, C.; Keskin, N.; Gulser, I. E.; Deniz, E.; Erman, M. B.; Uren, A.; Yakicier, C.; Muftuoglu, M.; N/A; Department of Chemical and Biological Engineering; Aydın, Derya; Erman, Burak; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; N/A; College of Engineering; N/A; 179997
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    Photocrosslinking of styrene-butadiene-styrene (SBS) networks formed by thiol-ene reactions and their influence on cell survival
    (IOP Publishing Ltd, 2015) Department of Chemical and Biological Engineering; N/A; Department of Chemical and Biological Engineering; Gidon, Doğan; Aydın, Derya; Kızılel, Seda; Researcher; Researcher; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; N/A; College of Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); N/A; N/A; 28376
    Styrene-butadiene-styrene (SBS) triblock copolymer has been conventionally used as synthetic rubber. However, the potential of SBS for biomedical applications has only been considered in limited earlier reports. Here, we demonstrate an effective approach to designing a photocrosslinked SBS network. Rheological analysis has been conducted for the investigation of the storage modulus of the resultant network. Crosslinked SBS networks were synthesized and characterized through optical and electron microscope imaging. The crosslink density of the network, calculated from swelling experiments, was 643 mol m(-3), where higher swelling in a hydrophobic medium was observed compared to the swelling measured in water. Cell survival analysis with HeLa cells and NIH/3T3 fibroblasts revealed that these networks are non-toxic, and that they could be considered for a variety of biomedical applications.
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    Design of stimuli-responsive drug delivery hydrogels
    (CRC Press, 2017) N/A; N/A; Department of Chemical and Biological Engineering; Aydın, Derya; Alipour, Mohammad; Kızılel, Seda; PhD Student; PhD 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; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 28376
    Stimuli-responsive hydrogels have become popular in medicine and polymer science as useful ‘smart’ devices due to their various properties such as overall biocompatibility, high drug loading capacity, and controlled molecule delivery. By tuning the polymer side chains and degree of crosslinking, these gels may exhibit swelling/shrinking behaviour in response to environmental stimuli such as light, pH, chemicals, temperature, mechanical strain, and electrical field. Sensitivity of these hydrogels enables precise control over fundamental material properties such as physical structure, porosity, swelling behaviour, mechanical strength and drug permeability. Temperature and pH alterations are examples of physiological deviations that are commonly considered for the design of responsive hydrogels, specifically for site-specific controlled drug delivery. A class of hydrogels known as multi-responsive hydrogels can respond to more than one stimuli which make them tunable and controllable with improved biomimetic properties well-suited for controlled and site specific drug delivery. Despite all these attractive properties of stimuli-responsive hydrogels, slow response time may cause some limitations in practical applications. Reduced hydrogel thickness may decrease the response time of the gel to a stimulus; however, this 2may lead to mechanically fragile hydrogel structures. Therefore, practical applications need significant improvement in hydrogel design to improve response time considering mechanical properties, biocompatibility, and biodegradability. This chapter highlights recent progress in the field of stimuli-responsive hydrogels, focusing primarily on drug delivery vehicles.
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    Gelation-stabilized functional composite-modified bitumen for anti-icing purposes
    (Amer Chemical Soc, 2015) Canıaz, Ramazan O.; N/A; N/A; Department of Chemical and Biological Engineering; Aydın, Derya; Kızılel, Rıza; Kızılel, Seda; PhD Student; Researcher; 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; N/A; College of Engineering; N/A; 114475; 28376
    Ionic salts as anti-icing agents have been extensively used to eliminate accumulation of ice on asphalt surfaces. However, salt can be easily removed by rain or automobiles and requires frequent application on roads. Besides this economic consideration, anti-icing agents compromise the mechanical properties of asphalt and have a negative impact on living organisms and the environment when used in large amounts. Incorporation of hydrophilic salts into bitumen, a hydrophobic asphalt binder, and controlled release of specific molecules from this hydrophobic medium can provide an effective solution for reducing ice formation on pavements. Bitumen has previously been modified by various polymers, including styrene-butadiene-styrene (SBS) for improved strength and thermomechanical properties. However, an anti-icing function was not considered in those previous designs. In a previous study, we developed a functional polymer composite consisting of potassium formate (HCOOK) salt pockets dissolved in a hydrophilic gel medium and dispersed in a hydrophobic SBS polymer matrix. Here, we developed an innovative method to obtain polymer composite-modified bitumen and investigated further the anti-icing properties of the functional bitumen. We improved incorporation of this polymer composite into bitumen and demonstrated proper distribution of the composite within bitumen through morphological and rheological analysis. We characterized the anti-icing properties of modified bitumen surfaces and demonstrated significant increases in freezing delay of composite-modified bitumen compared to base bitumen in a temperature- and humidity-controlled chamber. In addition, we characterized the release of HCOOK salt from polymer composite-modified bitumen and observed salt release within the range of 1.07-10.8% (w/w) in 67 days, depending on the composite content. The results demonstrate the potential of this polymer composite-modified bitumen for anti-icing functionality and for industrially relevant applications.
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    PublicationOpen Access
    Anti-icing properties on surfaces through a functional composite: effect of ionic salts
    (American Chemical Society (ACS), 2018) Department of Mathematics; Aydın, Derya; Akolpoğlu, Mükrime Birgül; Kızılel, Rıza; Kızılel, Seda; Researcher; Master Student; Researcher; Faculty Member; Department of Mathematics; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; N/A; 28376
    This study reports the potential of a unique functional composite for anti-icing applications. To date, various ionic salt formulations have been applied to prevent ice accumulation on surfaces. However, salt can be removed by external factors and large amounts must be used to attain anti-icing properties. Incorporating hydrophilic salts into hydrophobic mediums and controlled release of specific agents can provide effective solution to reduce ice accumulation on surfaces. Here, we developed functional polymer composites with salt pockets of altered ionic salts consisting of potassium formate (KCOOH), sodium chloride (NaCl), or magnesium chloride (MgCl2). We dissolved ionic salts in hydrophilic gel domains and dispersed in a hydrophobic styrene-butadiene-styrene polymer matrix. Na+ and Cl- ions delayed ice formation by 42.6 min at -2 degrees C compared to that for unmodified surfaces. Functional composites prepared with the NaCl ionic salt exhibited better anti-icing behavior at -2 degrees C because of their high concentration compared to that of the composites prepared with KCOOH and MgCl2 ionic salts. We also characterized the release of ionic salts from composite-modified hydrophobic medium separately up to 118 days. Furthermore, we monitored freezing of water on composite-incorporated or composite-coated hydrophobic surfaces in a camera-integrated cold chamber with a uniform temperature (-2 degrees C). The results demonstrated significant increases in the delay of freezing on composite-incorporated or composite-coated surfaces compared to that on controls. We observed altered effects of each ionic salt on the mechanical, morphological, and functional properties of the composite-incorporated or composite-coated hydrophobic surfaces. Our results suggested that the efficiency of a polymer composite to promote anti-icing behavior on a surface is directly related to the type and concentration of the particular ionic salt incorporation into the composite. This approach is promising and demonstrates significant potential of the ionic salt embedded within polymer composite-modified hydrophobic surfaces to attain delayed icing function.
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    PublicationOpen Access
    P2X7 receptor antagonist delivery vehicle based on photocrosslinked amphiphilic hybrid gels
    (Royal Society of Chemistry (RSC), 2018) Department of Chemical and Biological Engineering; Aydın, Derya; Kızılel, Seda; Researcher; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; Graduate School of Sciences and Engineering; N/A; 28376
    We report here a method for the synthesis of a unique hybrid gel system for the sustained delivery of P2X7 receptor (P2X7R) antagonist. P2X7R has been reported as a key mediator in inflammatory processes and controlled delivery of this molecule would be critical for the treatment of inflammatory arthritis. The hybrid gel designed here for the sustained delivery of P2X7R antagonists is based on crosslinked hydrophobic styrene-butadiene-styrene (SBS) polymer as a continuous network, where hydrogel particles prepared with hydrophilic poly(ethylene glycol) (PEG) were embedded into this system. PEG hydrogel particle-incorporated SBS gels were characterized through electron microscopy, water contact angle observations, and strong mechanical properties were confirmed through nanoindentation measurements. The release of P2X7R antagonist from these hybrid hydrogel-elastomer system demonstrated a sustained drug release profile up to 28 days at physiological pH, which was not observed in earlier reports. We obtained drug release percentages ranging from 49.72% to 93.04% which indicated the tunability of release through SBS crosslinking and hydrophilic/hydrophobic nature of SBS. This tunability is significant to achieve simultaneous improvements in drug efficacy with reduced side effects. CellTiter-Glo luminescence measurements using human kidney cells revealed that these networks are non-toxic and highly biocompatible with percent cell viabilities of higher than 85%. The approach presented here with crosslinked, amphiphilic and elastic SBS gel systems is not only promising for extended release of P2X7R antagonist but could also allow for incorporation of different molecules so that simultaneous/sequential and extended release profiles for therapeutic molecules could be achieved.
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    PublicationOpen Access
    Nanoparticle and gelation stabilized functional composites of an ionic salt in a hydrophobic polymer matrix
    (Public Library of Science, 2014) Department of Chemistry; Demirel, Adem Levent; Kanyas, Selin; Aydın, Derya; Kızılel, Rıza; Kızılel, Seda; Faculty Member; Researcher; Researcher; Faculty Member; Department of Chemistry; The Center for Computational Biology and Bioinformatics (CCBB); College of Engineering; College of Sciences; 6568; N/A; N/A; N/A; 28376
    Polymer composites consisted of small hydrophilic pockets homogeneously dispersed in a hydrophobic polymer matrix are important in many applications where controlled release of the functional agent from the hydrophilic phase is needed. As an example, a release of biomolecules or drugs from therapeutic formulations or release of salt in anti-icing application can be mentioned. Here, we report a method for preparation of such a composite material consisted of small KCOOH salt pockets distributed in the styrene-butadiene-styrene (SBS) polymer matrix and demonstrate its effectiveness in anti-icing coatings. The mixtures of the aqueous KCOOH and SBS-cyclohexane solutions were firstly stabilized by adding silica nanoparticles to the emulsions and, even more, by gelation of the aqueous phase by agarose. The emulsions were observed in optical microscope to check its stability in time and characterized by rheological measurements. The dry composite materials were obtained via casting the emulsions onto the glass substrates and evaporations of the organic solvent. Composite polymer films were characterized by water contact angle (WCA) measurements. The release of KCOOH salt into water and the freezing delay experiments of water droplets on dry composite films demonstrated their anti-icing properties. It has been concluded that hydrophobic and thermoplastic SBS polymer allows incorporation of the hydrophilic pockets/phases through our technique that opens the possibility for controlled delivering of anti-icing agents from the composite.