Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Robust CVD Polymer Encapsulation for Thermally and Chemically Resistant Fluorescent Sensor Nanoprobes(Elsevier Ltd, 2026) Karabıyık, M.; Cihanoğlu, G.; Ebil, Ö.Semiconductor quantum dots (QDs) are attractive fluorophores for sensor applications due to their narrow emission bandwidths and high photostability; however, their performance is often limited by insufficient chemical and thermal durability under operating conditions. In this study, a solvent-free encapsulation strategy based on initiated chemical vapor deposition (iCVD) is proposed to enhance the stability of QD-based sensor nanoprobes. Cross-linked poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate) (ECOP) thin films were conformally deposited as encapsulation layers onto CdTe QD-functionalized poly(GMA) sensor surfaces. The encapsulated nanoprobes were evaluated under chemically aggressive environments (water, salt water, toluene, and sulfuric acid) and elevated temperatures. Following exposure to aggressive solvents, both the polymer film thickness variation and QD fluorescence intensity change remained below 10 %, confirming the robustness of the cross-linked network. Also, thermal durability tests showed stable fluorescence performance after annealing at 250 °C, with structural and optical changes remaining within the accepted 10 % threshold. The results demonstrate that coatings deposited using iCVD exhibit conformal coverage and enhanced stability. This enables reliable protection of QD-based sensor nanoprobes without compromising optical performance. This study presents a promising method to extend the operational lifetime and environmental durability of QD-integrated sensor platforms by using chemically and thermally stable polymer encapsulation. © 2026 Elsevier LtdArticle Citation - WoS: 10Citation - Scopus: 10An Efficient Method of Improving Essential Oil Retention and Sustained Release of Chitosan Films: Ultrasound-Assisted Preparation of Chitosan Composites With Surface Active Chickpea Proteins(Elsevier, 2024) Barış Kavur, Pelin; Yemenicioğlu, AhmetThis work aimed at preparing chitosan (CHI) composites with surface active chickpea protein (CP) showing better eugenol (EUG) retention and sustained release capacity than pristine CHI films. For this purpose, ionic complexation of CHI with CP (CHI:CP ratio = 2:1, w/w) in the presence of EUG at pH 5.0 was achieved using mechanical homogenization alone (HM) or in combination with ultrasonic homogenization (HM-HUS). The HM-HUS treatment provided better solubility of CP (4.4-fold), increased emulsified EUG in film-forming solutions, and denser films than HM treatment. The composite films obtained using HM-HUS (FLMCHI-CP-EUG/HM-HUS) retained 1.2–1.4-fold higher EUG after drying, and showed almost 2-fold slower EUG release in air at room temperature than composite films prepared by HM, and control CHI films prepared by HM (FLMCHI-EUG/HM) or HM-HUS (FLMCHI-EUG/HM-HUS). The FLMCHI-CP-EUG/HM-HUS films also showed better moisture barrier and mechanical properties than other films. The developed films were proved in a challenging coating application with onions. Escherichia coli and Listeria innocua counts of inoculated and FLMCHI-CP-EUG/HM-HUS (average coating thickness = 4.5 ± 1.3 μm) coated onions were significantly lower than those of uncoated (2.8 and 3.8 log) and FLMCHI/HM-HUS (1.4 and 1.3 log) coated onions after 5-days at room temperature. FLMCHI-CP-EUG/HM-HUS coating also reduced percentage of sprouted onions from 30 to 10% during storage. EUG odor of coated onions could not have been detected by 80% of panelists after 4 weeks. Compositing with CP boosts the performance of essential oil loaded CHI films by enabling use of film matrix as an encapsulant. © 2024 Elsevier LtdArticle Citation - WoS: 21Citation - Scopus: 22Characterization and Encapsulation Efficiency of Zein Nanoparticles Loaded With Chestnut Fruit Shell, Cedar and Sweetgum Bark Extracts(Elsevier, 2023) Konuk Takma, Dilara; Bozkurt, Semra; Koç, Mehmet; Korel, Figen; Şahin Nadeem, HilalZein nanoparticles (ZNPs) loaded with bioactive extracts of chestnut (Castanea sativa Mill.) shell, cedar (Cedrus libani) and sweetgum (Liquidambar orientalis) bark wastes were produced using different methods. Nanoprecipitation, high-speed homogenization and ultrasonic homogenization allowed the fabrication of ZNPs with particle sizes smaller than 202.40 nm, 430.25 nm and 325.50 nm, respectively. The smallest nanoparticle size was achieved at 132.81 nm for sweetgum bark extract-loaded ZNPs obtained by the nanoprecipitation method. Encapsulation efficiency (EE) was between 34.03 and 96.83% for all zein nanoparticles fabricated under different mixtures and process conditions. Zein concentration and extract ratio played an essential role in the EE of nanoparticles. The best conditions were determined to obtain the desired properties of ZNPs based on particle size, polydispersity index and EE by using a central composite rotatable design. The nanoprecipitation method was more appropriate for producing chestnut and cedar shell/bark extract-loaded nanoparticles. In contrast, the high-speed homogenization method was suitable for producing sweetgum bark extract-loaded nanoparticles. As a result of the encapsulation of various shell/bark extracts within zein nanoparticles, value-added products were generated from wastes having bioactive compounds. The developed zein nanoparticles for each extract type would offer eco-friendly, simple and safe food processing and packaging systems. © 2023Article Citation - WoS: 6Citation - Scopus: 8Flexible and Expandable Robot for Tissue Therapies - Modeling and Design(IEEE, 2021) Atwya, Mohamed; Kavak, Can; Alisse, Elodie; Liu, YanQiang; Damian, Dana D.Objective: Implantable technologies should be mechanically compliant with the tissue in order to maximize tissue quality and reduce inflammation during tissue reconstruction. We introduce the development of a flexible and expandable implantable robotic (FEIR) device for the regenerative elongation of tubular tissue by applying controlled and precise tension to the target tissue while minimizing the forces produced on the surrounding tissue. Methods: We introduce a theoretical framework based on iterative beam theory static analysis for the design of an expandable robot with a flexible rack. The model takes into account the geometry and mechanics of the rack to determine a trade-off between its stiffness and capability to deliver the required tissue tension force. We empirically validate this theory on the benchtop and with biological tissue. Results: We show that FEIR can apply the required therapeutical forces on the tissue while reducing the amount of force it applies to the surrounding tissues as well as reducing self-damage. Conclusion: The study demonstrates a method to develop robots that can change size and shape to fit their dynamic environment while maintaining the precision and delicacy necessary to manipulate tissue by traction. Significance: The method is relevant to designers of implantable technologies. The robot is a precursor medical device for the treatment of Long-Gap Esophageal Atresia and Short Bowel Syndrome.Article Citation - WoS: 106Citation - Scopus: 123A Review of Current and Future Food Applications of Natural Hydrocolloids(John Wiley and Sons Inc., 2020) Yemenicioğlu, Ahmet; Farris, Stefano; Türkyılmaz, Meltem; Güleç, ŞükrüThe main aim of this review paper was to focus on current and potential future sources and food applications of natural hydrocolloids in the food industry. The emerging research trends, problems, new methods and alternative approaches in production, environmental concerns, market trends and newly discovered health benefits have been discussed for natural hydrocolloids of commercial relevance. The rheological and surface active properties, interactions, functional properties, films and coatings, encapsulation applications and nanotechnology uses of natural hydrocolloids have been discussed in the light of recent developments. This review also reflected the most up-to-date concepts of applying natural hydrocolloids to meet consumer's and food sector's sophisticated demands related to food products.Article Citation - WoS: 22Citation - Scopus: 27Mechanisms Behind Slow Photoresponse Character of Pulsed Electron Deposited Zno Thin Films(Elsevier, 2020) Özdoğan, Mehmet; Çelebi, Cem; Utlu, GökhanSemiconducting Zinc Oxide (ZnO) is ideal candidate for ultraviolet (UV) photodetector due to its promising optoelectronic properties. Photoconductive type ZnO photodetectors, which is fabricated in metal-semiconductor-metal configuration, show mostly very high photoconductivity under UV light, but they are plagued by slow photoresponse time as slow as several tens of hours, even more. Most of the studies claimed that atmospheric adsorbates such as water and oxygen create charge traps states on the surface and remarkably increase both the photoconductivity and response time. There are also limited studies, which claim that the defect states acting as hole trap centers prolong response time significantly. However, the underlying physical mechanism is still unclear. Here we study the effects of both adsorbates and defect-related states on the photoresponse character of Pulsed Electron Deposited ZnO thin films. In order to distinguish between these two mechanisms, we have compared the time-dependent photoresponse measurements of bare-ZnO and SiO2 encapsulated-ZnO thin film samples taken under UV light and high vacuum. We show that the dominant mechanism of photoresponse in ZnO is the adsorption/desorption of oxygen and water molecules even when the measurement is performed in high vacuum. After the encapsulation of sample surface by a thin SiO2 layer, the adsorption/desorption rates can significantly improve, and the effects of these molecules partially removed.Article Citation - WoS: 6Citation - Scopus: 7Epitaxial Graphene Thermistor for Cryogenic Temperatures(Elsevier, 2018) Kalkan, Sırrı Batuhan; Yiğen, Seren; Çelebi, CemThe thermal responsivity of monolayer epitaxial graphene grown on the Si-face surface of semi-insulating SiC substrate is investigated as a function of temperature below 300 K. The measurements showed that adsorption/desorption of atmospheric adsorbates can randomly modify the electrical characteristics of graphene which is indeed undesirable for consistent temperature sensing operations. Therefore, in order to avoid the interaction between graphene layer and adsorbates, the grown graphene layer is encapsulated with a thin SiO2 film deposited by Pulsed Electron Deposition technique. Temperature dependent resistance measurement of encapsulated graphene exhibited a clear thermistor type behavior with negative temperature coefficient resistance character. Both the sensitivity and transient thermal responsivity of the SiO2/graphene/SiC sample were found to be enhanced greatly especially for the temperatures lower than 225 K. The experimentally obtained results suggest that SiO2 encapsulated epitaxial graphene on SiC can be used readily as an energy efficient and stable temperature sensing element in cryogenic applications.Article Citation - WoS: 52Citation - Scopus: 55Wheatgrass Juice To Wheat Grass Powder: Encapsulation, Physical and Chemical Characterization(Elsevier Ltd., 2017) Akbaş, Elif; Kilercioğlu, Mete; Önder, Özge Nur; Köker, Alperen; Söyler, Betül; Öztop, Mecit HalilWheatgrass juice (Triticum aestivum L.) is known as a healthy drink due to its high antioxidant activity and phenolic content. In order to avoid the undesirable odor and protect the functional compounds, wheatgrass juice was encapsulated using maltodextrin and whey protein. Antioxidant and phenolic content, mean particle size and distribution, morphology, simulated digestion and thermal stability experiments were conducted on the encapsulated powders. Results showed that antioxidant activity was in between 0.30 and 0.06 mg 2-diphenyl-1-picrylhydrazyl (DPPH)/g powder and phenolic content was 3.52–2.28 mg gallic acid equivalent (GAE)/g powder. Encapsulated powders showed good stability in gastric juice and had 62% higher phenolic content compared to the intestinal fluid within 10 min digestion. Phenolic content of powders was also protected against thermal treatment at 40 °C, 55 °C and 70 °C. Kinetic parameters for degradation of the phenolics were well estimated (R2⩾0.85) using fractional conversion model.Article Citation - WoS: 35Citation - Scopus: 41Protection of Lactobacillus Acidophilus Nrrl-B 4495 Under in Vitro Gastrointestinal Conditions With Whey Protein/Pullulan Microcapsules(Elsevier Ltd., 2015) Çabuk, Burcu; Tellioğlu Harsa, ŞebnemIn this research, whey protein/pullulan (WP/pullulan) microcapsules were developed in order to assess its protective effect on the viability of Lactobacillus acidophilus NRRL-B 4495 under in vitro gastrointestinal conditions. Results demonstrated that WP/pullulan microencapsulated cells exhibited significantly (p ≤ 0.05) higher resistance to simulated gastric acid and bile salt. Pullulan incorporation into protein wall matrix resulted in improved survival as compared to free cells after 3 h incubation in simulated gastric solution. Moreover WP/pullulan microcapsules were found to release over 70% of encapsulated L. acidophilus NRRL-B 4495 cells within 1 h. The effect of encapsulation during refrigerated storage was also studied. Free bacteria exhibited 3.96 log reduction while, WP/pullulan encapsulated bacteria showed 1.64 log reduction after 4 weeks of storage.Article Citation - WoS: 12Citation - Scopus: 15Improved Viability of Lactobacillus Acidophilus Nrrl-B 4495 During Freeze-Drying in Whey Protein-Pullulan Microcapsules(Informa Healthcare, 2015) Çabuk, Burcu; Tellioğlu Harsa, ŞebnemIn this research, pullulan was incorporated in protein-based encapsulation matrix in order to assess its cryoprotective effect on the viability of freeze-dried (FD) probiotic Lactobacillus acidophilus NRRL-B 4495. This study demonstrated that pullulan in encapsulation matrix resulted in a 90.4% survival rate as compared to 88.1% for whey protein (WPI) encapsulated cells. The protective effects of pullulan on the survival of FD-encapsulated cells in gastrointestinal conditions were compared. FD WPI-pullulan capsules retained higher survived cell numbers (7.10 log CFU/g) than those of FD WPI capsules (6.03 log CFU/g) after simulated gastric juice exposure. Additionally, use of pullulan resulted in an increased viability after bile exposure. FD-free bacteria exhibited 2.18 log CFU/g reduction, while FD WPI and FD WPI-pullulan encapsulated bacteria showed 0.95 and 0.49 log CFU/g reduction after 24 h exposure to bile solution, respectively. Morphology of the FD microcapsules was visualized by scanning electron microscopy. © 2015 Informa UK Ltd.