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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Item Metadata only 3D-printed microrobots: translational challenges(MDPI, 2023) 0000-0003-4604-217X; 0000-0002-5295-5701; 0000-0003-0519-4513; Yetisen, Ali K.; Department of Mechanical Engineering; N/A; N/A; Taşoğlu, Savaş; Sarabi, Misagh Rezapour; Karagöz, Ahmet Agah; Faculty Member; PhD Student; PhD Student; KU Arçelik Research Center for Creative Industries (KUAR) / KU Arçelik Yaratıcı Endüstriler Uygulama ve Araştırma Merkezi (KUAR); Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Koç Üniversitesi İş Bankası Yapay Zeka Uygulama ve Araştırma Merkezi (KUIS AI)/ Koç University İş Bank Artificial Intelligence Center (KUIS AI); College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 291971; N/A; N/AThe science of microrobots is accelerating towards the creation of new functionalities for biomedical applications such as targeted delivery of agents, surgical procedures, tracking and imaging, and sensing. Using magnetic properties to control the motion of microrobots for these applications is emerging. Here, 3D printing methods are introduced for the fabrication of microrobots and their future perspectives are discussed to elucidate the path for enabling their clinical translation.Item Metadata only Enhancing thermoelectric and mechanical properties of P-Type (Bi, Sb)2Te3 through rickardite mineral (Cu2.9Te2) incorporation(Amer Chemical Soc, 2023) 0000-0003-1164-1973; 0000-0001-9098-2869; N/A; Department of Chemistry; N/A; N/A; Aydemir, Umut; Yahyaoğlu, Müjde; Sağlık, Kıvanç; Faculty Member; PhD Student; PhD Student; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 58403; N/A; N/ABi2Te3-based alloys are widely utilized in Peltier coolers owing to their highest thermoelectric performance at near-room-temperatures. However, their peak dimensionless thermo-electric figure of merit, zT, is limited to a narrow temperature window due to minority carrier excitation emerging upon heating at around 400 K. Here, we show how this issue can be overcome by incorporating a synthetic rickardite mineral, Cu3-xTe2, in p-type (Bi, Sb)2Te3. The significant enhancement of the electronic and thermal properties could be achieved due to small Cu incorporation into the crystal structure of (Bi, Sb)2Te3 and homogeneous precipitation of Cu3-xTe2 at the grain boundaries. This leads to a high average zT value (zTave) of 1.22 between 350 and 500 K for two compositions, Bi0.5Sb1.5Te3 (BST-5) and Bi0.3Sb1.7Te3 (BST-3), with peak zT values of 1.32 at 467 K and 1.30 at 400 K, respectively. These high zT values result in a considerably high maximum device ZT of ca. 1.15 and a theoretical efficiency of up to 7% between 325 and 525 K. Additionally, room-temperature micro-hardness is substantially improved, which is desirable for constructing reliable and durable thermoelectric modules.Item Metadata only Tetra-functional multilayer coatings for cardiovascular stent materials(Elsevier, 2023) 0000-0001-6624-3505; 0000-0002-6976-942X; 0000-0001-6753-9316; 0000-0001-5547-6653; 0000-0002-7698-0872; N/A; 0000-0002-4588-5231; 0000-0003-0984-0375; N/A; Department of Chemical and Biological Engineering; Department of Chemistry; N/A; N/A; N/A; Department of Molecular Biology and Genetics; N/A; N/A; N/A; Kavaklı, İbrahim Halil; Güner, Pınar Tatar; Motallebzadeh, Amir; Yalçın, Özlem; Gürpınar, Yunus; Sürme, Saliha; Ijaz, Aatif; Saadatlou, Ghazaleh Azizi; Sipahioğlu, Dilara; Faculty Member; Teaching Faculty; Researcher; Faculty Member; Researcher; Teaching Faculty; Researcher; PhD Student; Master Student; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); College of Engineering; College of Sciences; N/A; School of Medicine; N/A; College of Sciences; N/A; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 40319; 188227; N/A; 218440; N/A; 389349; N/A; N/A; N/AFunctional coatings have been of great interest in enhancing the performance of implants in recent years. Here, for the first time, preparation and characterization of a tetra-functional coating is reported, exhibiting anticorrosion, antibacterial, biocompatible, and anticoagulant behaviors. Poly(2-ethyl-2-oxazoline)-copolyethyleneimine (PEOX-co-PEI) stabilized silver nanoparticles (AgNPs) and heparin were used to prepare the multifunctional multilayers. The coatings were deposited on nitinol and 316 L stainless steel substrates, the most used materials in coronary stents, via layer-by-layer (LbL) technique. Corrosion current density values obtained from Tafel plots are 1.61 x 10-9 A/cm2 and 6.79 x 10-8A/cm2 for coated and uncoated 316 L substrate, respectively. Similarly, the corrosion current density values shifted from 1.00 x 10-8A/cm2 for uncoated nitinol to 4.77 x 10-10A/cm2 after coating. Contact killing method against gram-positive (Staphylococcus aureus) and gram-negative (Pseudomonas aeruginosa) bacterial species concluded that the presence of the coating on the surfaces of the materials reduces the number of the survived colonies (in CFU/mL) for more than 99.9%independent of the underlying metal within 3 hours of incubation time. Prepared coatings demonstrated above 90% relative viability compared to the positive control in MTT assay using human umbilical vein endothelial cells (HUVEC), indicating no cytotoxic effect on adjacent healthy cells. The coagulation assay also exhibited a 50% reduction in the coagulation rate after coating compared to the bare substrates, confirming the antithrombogenicity of the coatings.Item Metadata only Mesoporous carbon encapsulated zinc oxide nanorods derived from plant species 'Argyreia sharadchandrajii' for live cell imaging of drug delivery and multimodal bioactivities(Royal Soc Chemistry, 2023) 0000-0002-2376-1246; Bhosale, Sneha R.; Jagadhane, Kishor S.; Bhosale, Rakhee R.; Vanalakar, Sharadrao A.; Patil, Devashree N.; Dhavale, Rushikesh P.; Shimpale, Vinod B.; Kolekar, Govind B.; Anbhule, Prashant V.; N/A; Qureshi, Mohammad Haroon; PhD Student; Graduate School of Sciences and EngineeringIn this report, we develop a drug delivery system by binding Argyreia sharadchandrajii (A. S.) biomass-derived carbon encapsulated on the surface of zinc oxide (ZnO) nanorods by a two-step method. Firstly, we prepared mesoporous carbon (MC) by pyrolysis under an inert atmosphere at 800 & DEG;C for 3 h. Simultaneously, hydrothermal synthesis of ZnO nanorods was performed, followed by composite formation with surface modification of ZnO nanorods with carbon particles. The physicochemical properties of the mesoporous carbon encapsulated ZnO nanorods were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis, Brunauer-Emmett-Teller (BET) analysis, etc. The mesoporous carbon encapsulated ZnO nanorods revealed a wurtzite hexagonal crystal structure. The SEM image showed the mesoporous carbon covered on the surface of the ZnO nanorod-like morphology with an average diameter of 300-400 nm and an average length of 1.2 & mu;m. Based on these characterizations, we have reported several bioactivities like antioxidant, antimicrobial, anticancer, and drug delivery. The carbon/ZnO composite (C@Z) loaded with doxorubicin (DOX) (C@Z-DOX) manifested sustained drug release to live cancer cells. Taking into consideration the ubiquitous availability of carbon sources and the facile synthetic strategy of composites for promising drug delivery studies and bioactivities, this approach could acquire remarkable results in biomedical research.Item Metadata only Tunable photocatalytic activity of CoFe prussian blue analogue modified SrTiO3 core-shell structures for solar-driven water oxidation(American Chemical Society, 2023) 0000-0003-1164-1973; 0000-0002-2991-5488; Sadigh Akbari, Sina; Lomlu, Rana; Karadas, Ferdi; Department of Chemistry; N/A; Aydemir, Umut; Peighambardoust, Naeimeh Sadat; Faculty Member; Researcher; Koç University Boron and Advanced Materials Application and Research Center (KUBAM) / Koç Üniversitesi Bor ve İleri Malzemeler Uygulama ve Araştırma Merkezi (KUBAM); College of Sciences; N/A; 58403; N/AThis study presents a pioneering semiconductor-catalyst core-shell architecture designed to enhance photocatalytic water oxidation activity significantly. This innovative assembly involves the in situ deposition of CoFe Prussian blue analogue (PBA) particles onto SrTiO3 (STO) and blue SrTiO3 (bSTO) nanocubes, effectively establishing a robust p-n junction, as demonstrated by Mott-Schottky analysis. Of notable significance, the STO/PB core-shell catalyst displayed remarkable photocatalytic performance, achieving an oxygen evolution rate of 129.6 μmol g-1 h-1, with stability over an extended 9-h in the presence of S2O82- as an electron scavenger. Thorough characterization unequivocally verified the precise alignment of the band energies within the STO/PB core-shell assembly. Our research underscores the critical role of tailored semiconductor-catalyst interfaces in advancing the realm of photocatalysis and its broader applications in renewable energy technologies. © 2023 The Authors. Published by American Chemical Society.Item Metadata only The effect of synthesis conditions and process parameters on aerogel properties(Frontiers Media Sa, 2023) 0000-0001-6539-7748; 0000-0003-4471-2301; 0000-0001-6443-5669; 0000-0002-7380-5550; Payanda Konuk, Ozge; Alsuhile, Ala A. A. M.; Yousefzadeh, Hamed; Ulker, Zeynep; Bozbag, Selmi E.; Garcia-Gonzalez, C. A.; Smirnova, I.; Erkey, Can; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; N/A; N/A; Erkey, Can; Bozbağ, Selmi Erim; Konuk, Özge Payanda; Alsuhile, Ala Abdulalem Abdo Moqbel; Faculty Member; Researcher; PhD Student; PhD Student; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 29633; N/A; N/A; N/AAerogels are remarkable nanoporous materials with unique properties such as low density, high porosity, high specific surface area, and interconnected pore networks. In addition, their ability to be synthesized from various precursors such as inorganics, organics, or hybrid, and the tunability of their properties make them very attractive for many applications such as adsorption, thermal insulation, catalysts, tissue engineering, and drug delivery. The physical and chemical properties and pore structure of aerogels are crucial in determining their application areas. Moreover, it is possible to tailor the aerogel properties to meet the specific requirements of each application. This review presents a comprehensive review of synthesis conditions and process parameters in tailoring aerogel properties. The effective parameters from the dissolution of the precursor step to the supercritical drying step, including the carbonization process for carbon aerogels, are investigated from the studies reported in the literature.Item Metadata only Synthesis and capacitive performance of ZrB2 and its composites as supercapacitor electrodes(Elsevier, 2023) 0000-0001-6756-3180; 0000-0003-1925-9453; N/A; Buldu-Akturk, Merve; Erdem, Emre; Department of Chemistry; N/A; N/A; Balcı, Özge Çağıran; Paksoy, Aybike; Arabi, Seyedehnegar; Researcher; Master Student; PhD Student; Koç University Boron and Advanced Materials Application and Research Center (KUBAM) / Koç Üniversitesi Bor ve İleri Malzemeler Uygulama ve Araştırma Merkezi (KUBAM); College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 295531; N/A; N/AThe possibility of using zirconium diboride (ZrB2) as an electrode for supercapacitor devices has yet to be extensively studied, even though there is a wealth of literature on various properties of ZrB2. In this study, ZrB2 and its composites were directly assembled as electrode materials into symmetric and asymmetric supercapacitor devices. ZrB2 powders were synthesized by using mechanical activation assisted direct synthesis route followed by a purification step. Powders were illustrated with precise size tuning in the 200-500 nm range. Then, the ZrB2-based composite materials containing silicon carbide (SiC) particles were prepared by using a mechanical alloying process. Microstructural and thermal analyses of the particles were carried out and optimum powders were selected for the measurements of electrochemical performance. Both symmetric and asymmetric supercapacitors exhibited excellent cycling performances: After 50 cycles, the devices display 79 and 69% capacitance retention as well as 108 and 123% coulombic efficiency at 0.1 A g-1, respectively for the symmetric ZrB2/ZrB2 and asymmetric ZrB2/ZrB2-15 wt%SiC supercapacitors. The symmetric supercapacitor exhibited higher performance than asymmetric one with a specific energy and power density of 4.2 W h kg-1 and 150 W kg-1, respectively. As a result, high energy density and high capacity values, and excellent cycling performances are obtained, meaning that ZrB2 and its composites are promising materials for energy storage purposes.Item Metadata only Physical exercise in sports sciences and rehabilitation: physiology, clinical applications and real practice(MDPI, 2023) 0000-0002-2052-6072; de Sire, Alessandro; N/A; Taşkıran, Özden Özyemişçi; Faculty Member; School of Medicine; 133091Item Metadata only Understanding the enhanced corrosion performance of two novel Ti- based biomedical high entropy alloys(Elsevier Science Sa, 2023) 0000-0001-9961-7702; 0000-0001-6763-5770; 0000-0001-8160-0478; 0000-0002-8430-6941; 0000-0002-9841-7028; 0000-0003-4718-1243; Unal, U.; Maier, H. J.Yilmaz, R.; Department of Mechanical Engineering; N/A; N/A; N/A; N/A; Department of Chemistry; Canadinç, Demircan; Özdemir, Hüseyin Can; Kılıç, Elif Bedir; Nazarahari, Alireza; Yılmaz, Bengisu; Ünal, Uğur; Faculty Member; PhD Student; PhD Student; PhD Student; PhD Student; Faculty Member; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of Engineering; 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 Sciences; 23433; N/A; N/A; N/A; N/A; 42079The microstructure and corrosion behavior of two novel biomedical high entropy alloys (HEA)s, namely Hf27Nb12Ta10Ti23Zr28 and Hf30Nb14Ta10Ti28Zr18 that were previously designed utilizing machine learning, were investigated in depth. The microstructure of the alloys was determined to be dendritic, with some elemental segregations governed by the solidification kinetics occurring during the arc-melting process. Static immersion experiments were carried out in artificial saliva (AS) and simulated body fluid (SBF) to investigate the ion release behavior of the HEAs and reveal the dissolution kinetics of the passive film forming on the surface. The composition of the corresponding surface oxide layers was examined using X-ray photoelectron spectroscopy, which provided detailed insight into the stability of passive oxide layers and sub-oxide formation. Potentiodynamic polarization experiments performed in AS and SBF at 37 oC demonstrated that both HEAs exhibit superior corrosion behavior as compared to the CoCrMo alloy, one of the conventional metallic implant materials of choice. (c) 2023 Elsevier B.V. All rights reserved.Item Metadata only Aqueous colloidal nanoplatelets for imaging and improved ALA-based photodynamic therapy of prostate cancer cells(Royal Soc Chemistry, 2023) 0000-0001-5601-8814; 0000-0003-4952-7981; 0000-0001-6573-8565; Onbasli, Kubra; Demirci, Gozde; Isik, Furkan; Durmusoglu, Emek Goksu; Demir, Hilmi Volkan; Acar, Havva Yagci; Department of Chemistry; N/A; N/A; Acar, Havva Funda Yağcı; Demirci, Gözde; Onbaşlı, Kübra; Faculty Member; Master Student; PhD Student; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 178902; N/A; 365341Fluorescent, CdSe/CdS core/crown heterostructured nanoplatelets (NPLs) were transferred to the water via a simple, single-step ligand exchange using 2-mercaptopropionic acid in a simple extraction process. These stable, aqueous NPLs were loaded with a modal drug, 5-aminolevulinic acid (ALA). ALA-loaded NPLs emerged as a new class of theranostic nanoparticles for image-guided enhanced photodynamic therapy of both androgen-dependent and -independent human prostate cancer cells.