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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Publication Metadata only Robust adhesive nanocomposite sponge composed of citric acid and nano clays modified cellulose for rapid hemostasis of lethal non-compressible hemorrhage(Elsevier Ltd, 2024) Mahmoodzadeh,A; Valizadeh,N; Edalati,M; Khordadmehr,M; Salehi,R; Jarolmasjed,S; Gargari, Ziba Zakeri; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM)Massive bleeding control plays the main role in saving people's lives in emergency situations. Herein, modified cellulose-based nanocomposite sponges by polydopamine (PDA) and laponite nano-clay was developed to sturdily deal with non-compressible lethal severe bleeding. PDA accomplishes supreme adhesion in the bleeding site (similar to 405 kPa) to form strong physical barrier and seal the position. Sponges super porous (similar to 70 % porosity) and super absorbent capacity (48 g blood absorbed per 1 g sponge) by concentrating the blood cells and platelets provides the requirements for primary hemostasis. Synergistically, the nanocomposite sponges' intelligent chemical structure induces hemostasis by activation of the XI, IX, X, II and FVII factors of intrinsic and extrinsic coagulation pathways. Excellent hemostatic performance of sponges in-vitro was assessed by RBC accumulation (similar to 100 %), blood clotting index (similar to 10 %), platelet aggregation/activation (-93 %) and clotting time. The nanocomposite sponges depicted super performance in the fatal high-pressure non-compressible hemorrhage model by reducing of >2, 15 and 3 times in the bleeding amount at New Zealand rabbit's heart and liver, and rat's femoral artery bleeding models, respectively compared to commercial hemostatic agents (Pvalue<0.001). The in-vivo host response results exhibited biosafety with no systemic and significant local inflammatory response by hematological, pathological and biochemical parameters assessments.Publication Metadata only Optimization of argon-air DBD plasma-assisted grafting of polyacrylic acid on electrospun POSS-PCUU(Pergamon-Elsevier Science Ltd, 2023) Salehi, Roya; Mahkam, Mehrdad; Siahpoush, Vahid; Rahbarghazi, Reza; l; Abbasi, Farhang; Gargari, Ziba Zakeri; Sokullu, Emel; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); School of MedicineIt is accepted that significant interfacial reactions take place in engineered tissues between biomaterial surfaces and the host's tissue in the body. The lack of appropriate functional groups limits long-term biocompatibility and successful biological response of biomaterials. Therefore, the cell-biomaterial affinity should be increased by functional groups grafting to the surface of biomaterials which provide the basic properties of the desired tissue. For the first time in this study, PAAc grafting was performed using two-step argon-air DBD plasma at atmospheric pressure in a few seconds of exposure time, to modify the surface of POSS-PCUU nanofibers to selectively in-crease their superficial properties while maintaining the required mechanical properties. The Response Surface Methodology was used for experimental design to optimize the operating conditions of carboxylic acid grafting at the electrospun POSS-PCUU surface. Nanofiber surface modification was confirmed using ATR-FTIR, FE-SEM, AFM, WCA, and tensile test. The grafting of PAAc to the nanofiber surface was proved by the presence of a broad hydroxyl band in ATR-FTIR spectrum, the morphological changes observed in the SEM and AFM images, and the reduction of the water contact angle. The stress-strain behavior at the optimum point also showed an acceptable reduction in tensile strength. Furthermore, the effects of two variables, plasma processing time and plasma copolymerization time were optimized and investigated using the CCD method at five levels of carboxylic acid grafting density. The grafting of PAAc onto the nanofiber surface (73.69 +/- 2.1 mu g/cm2) produced at reaction conditions displayed great agreement with the predicted results by the model. Results showed that the modified PAAc-POSS-PCUU nanofibers will be a desirable surface for the immobilization of various ECM proteins with high potential in small-diameter vascular graft applications.Publication Metadata only Collision-induced state-changing rate coefficients for cyanogen backbones NCN 3Σ− and CNN 3Σ− in astrophysical environments(Royal Society of Chemistry, 2023) González-Sánchez, Lola; de la Fuente, Jorge Alonso; Sanz-Sanz, Cristina; Wester, Roland; Gianturco, Francesco A.; Department of Chemistry; Department of Chemistry; College of SciencesWe report quantum calculations involving the dynamics of rotational energy-transfer processes, by collision with He atoms in interstellar environments, of the title molecular species which share the presence of the CN backbone and are considered of importance in those environments. The latter structural feature is taken to be especially relevant for prebiotic chemistry and for its possible role in the processing of the heterocyclic rings of RNA and DNA nucleobases in the interstellar space. We carry out ab initio calculations of their interaction potentials with He atoms and further obtain the state-to-state rotationally inelastic cross sections and rate coefficients over the relevant range of temperatures. The similarities and differences between such species and other similar partners which have been already detected are analyzed and discussed for their significance on internal state populations in interstellar space for the two title molecular radicals.Publication Metadata only Three-body collisions driving the ion-molecule reaction c 2-+ h2 at low temperatures(Amer Chemical Soc, 2023) Lochmann, Christine; Notzold, Markus; Wild, Robert; Satta, Mauro; Gianturco, Francesco A.; Wester, Roland; Department of Chemistry; Department of Chemistry; College of SciencesWe report on the three-body reaction rate of C-2- with H-2 producing C2H- studied in a cryogenic 16-pole radio frequency ion trap. The reaction was measured in the temperature range from 10 to 28 K, where it was found to only take place via three-body collisions. The experimentally determined termolecular rate coefficient follows the form of a center dot(T/T)b 0 with T0 = 20 K, where a = 8.2(3) x 10(-30) cm(6)/s and b = -0.82(12) denotes the temperature dependence. We additionally performed accurate ab initio calculations of the forces between the interacting partners and carried out variational transition state theory calculations, including tunneling through the barrier along the minimum energy path. We show that, while a simple classical model can generally predict the temperature dependence, the variational transition state theoretical calculations, including accurate quantum interactions, can explain the dominance of three-body effects in the molecular reaction mechanism and can reproduce the experimentally determined reaction coefficients, linking them to a temperature-dependent coupling parameter for energy dissipation within the transition complex.Publication Metadata only Stepwise conversion of methane to methanol over Cu-mordenite prepared by supercritical and aqueous ion exchange routes and quantification of active Cu species by H2-TPR(Elsevier, 2023) Sushkevich, Vitaly; van Bokhoven, Jeroen A.; Department of Chemical and Biological Engineering; Yousefzadeh, Hamed; Bozbağ, Selmi Erim; Erkey, Can; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of EngineeringCopper-exchanged mordenite prepared by supercritical ion exchange (SCIE) and aqueous ion exchange (AIE) were investigated in stepwise conversion of methane to methanol. Increasing the oxygen activation temperature and methane reaction time enhances the methanol yield of copper-exchanged mordenite prepared by SCIE (CuMORS). The reducibility of Cu-MORS was compared with those of Cu-MORA prepared by aqueous ion exchange (AIE) using H-2-TPR. It was demonstrated for the first time that deconvoluted H2-TPR profile coupled with effects of Cu loading and oxygen activation temperature on methanol yield data can be used to distinguish the active Cu sites from inactive ones based on their reduction temperature. The copper species responsible for methane activation were found to be reduced below 150 C by H-2 in both Cu-MORS and Cu-MORA. From the stoichiometry of the reaction of H-2 with Cu2+ species, the average number of copper atoms of active sites were calculated as 2.07 and 2.80 for Cu-MORS and Cu-MORA, respectively. Differences in structure of copper species caused by the synthesis routes were also detected by in-situ FTIR upon NO adsorption indicating a higher susceptibility of CuMORS towards autoreduction. The results demonstrated the potential of TPR based methods to identify copper active sites and suggested the importance of site selective ion exchange in order to controllably synthesize active Cu species in zeolites.Publication Metadata only Solar-light-driven photocatalytic hydrogen evolution activity of gCN/WS2 heterojunctions incorporated with the first-row transition metals(Elsevier Science Sa, 2023) Acar, Eminegul Genc; Aslan, Emre; Patir, Imren Hatay; Department of Chemistry; Yılmaz, Seda; Eroğlu, Zafer; Metin, Önder; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; College of SciencesThe design of semiconductor-based heterojunctions is an effective strategy to build highly active photo-catalyst systems. In this study, tungsten disulfide (WS2) modified graphitic carbon nitride (gCN) hetero-junction (gCN/WS2) is incorporated with Co and Ni (gCN/WS2-Co and gCN/WS2-Ni) to enhance the photocatalytic hydrogen evolution reaction (HER) activity of gCN/WS2 via performing a chemical reduction method and characterized by advanced analytical techniques. The photocatalytic HER activities of gCN, gCN/ WS2, gCN/WS2-Ni and gCN/WS2-Co were measured as 0.126, 0.221, 0.237 and 0.249 mmol g-1h-1, respec-tively, under the visible light irradiation. The improvement of photocatalytic activity and stability of gCN/ WS2-Ni and gCN/WS2-Co nanocomposites could be attributed to the 2D/2D heterojunction structure, ex-tended light harvesting ability, increased electron-hole lifetime and decreased recombination rate of the charge carriers. Moreover, mechanistic studies revealed that a S-scheme heterojunction is attributed to the enhanced photocatalytic HER by the gCN/WS2-Ni and gCN/WS2-Co photocatalysts, which provides pro-moted efficiency by photocarrier transfer and separation.Publication Metadata only 3D printed styrax liquidus (liquidambar orientalis miller)-loaded poly (l-lactic acid)/chitosan based wound dressing material: fabrication, characterization, and biocompatibility results(Elsevier, 2023) Cakmak, Hanife Yuksel; Ege, Hasan; Yilmaz, Senanur; Agturk, Gokhan; Enguven, Gozde; Sarmis, Abdurrahman; Cakmak, Zeren; Gunduz, Oguzhan; Ege, Zeynep Ruya; Yöntem, Fulya Dal; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); School of MedicineThe medicinal plant of Styrax liquidus (ST) (sweet gum balsam) which extracted from Liquidambar orientalis Mill tree, was loaded into the 3D printed polylactic acid (PLA)/chitosan (CS) based 3D printed scaffolds to investigate its wound healing and closure effect, in this study. The morphological and chemical properties of the ST loaded 3D printed scaffolds with different concentrations (1 %, 2 %, and 3 % wt) were investigated by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR), respectively. In addition, the me-chanical and thermal properties of the materials were investigated by Tensile test and Differential Scanning Calorimetry (DSC), respectively. The antimicrobial activities of the ST loaded 3D printed scaffolds and their incubation media in the PBS (pH 7.4, at 37 degrees C for 24 h) were investigated on two Gram-positive and two Gram -negative standard pathogenic bacteria with the agar disc diffusion method. The colorimetric MTT assay was used to determine the cell viability of human fibroblast cells (CCD-1072Sk) incubated with free ST, ST loaded, and unloaded 3D printed scaffolds. The 1 % and 2 % (wt) ST loaded PLA/CS/ST 3D printed scaffolds showed an increase in the cell number. Annexin V/PI double stain assay was performed to test whether early or late apoptosis was induced in the PLA/CS/1 % ST and PLA/CS/2 % ST loaded groups and the results were consistent with the MTT assay. Furthermore, a wound healing assay was carried out to investigate the effect of ST loaded 3D printed scaffolds on wound healing in CCD-1072Sk cells. The highest wound closure compared to the control group was observed on cells treated with PLA/CS/1 % ST for 72 h. According to the results, novel biocompatible ST loaded 3D printed scaffolds with antimicrobial effect can be used as wound healing material for potential tissue engineering applications.Publication Metadata only Black phosphorus/WS2-TM (TM: Ni, Co) heterojunctions for photocatalytic hydrogen evolution under visible light illumination(MDPI, 2023) Acar, Emineguel Genc; Çekceoglu, Ilknur Aksoy; Aslan, Emre; Patir, Imren Hatay; Department of Chemistry; Yılmaz, Seda; Eroğlu, Zafer; Metin, Önder; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; College of SciencesBlack phosphorus (BP) has recently emerged as a versatile photocatalyst owing to its unique photophysical properties and tunable bandgap. Nonetheless, the rapid recombination of the photogenerated charges of pristine BP samples has significantly hindered its practical applications in photocatalysis. Herein, we report, for the first time, the effect of transition metal nanoparticles (Ni and Co) as co-catalysts on the photocatalytic activity of BP/tungsten disulfide (WS2) binary heterojunctions (BP/WS2-TM (TM: Ni, Co)) in the hydrogen evolution reaction (HER) under visible light irradiation (& lambda; > 420 nm). Ternary heterojunctions named BP/WS2-TM (TM: Ni, Co) were synthesized via a chemical reduction method, leading to the formation of an S-scheme heterojunction, in which BP acts as a reduction catalyst and WS2 serves as an oxidation catalyst. BP/WS2-Ni and BP/WS2-Co performed substantial amounts of hydrogen generation of 9.53 mmol h(-1)g(-1) and 12.13 mmol h(-1)g(-1), respectively. Moreover, BP/WS2-Co exhibited about 5 and 15 times higher photocatalytic activity compared to the binary BP/WS2 heterojunctions and pristine BP, respectively. The enhanced photocatalytic activity of the heterojunction catalysts is attributed to the extended light absorption ability, enhanced charge separation, and larger active sites. This study is the first example of photocatalytic hydrogen evolution from water by using Ni- and Co-doped binary BP/WS2 heterojunctions.Publication Metadata only Influence of soft segment structure, hydrogen bonding, and diisocyanate symmetry on morphology and properties of segmented thermoplastic polyurethanes and polyureas(Tubitak Scientific & Technological Research Council Turkey, 2023) Department of Chemistry; Yılgör, Emel; Yılgör, İskender; Department of Chemistry; College of SciencesA comprehensive review of the structure-morphology-property relations in segmented thermoplastic polyurethanes and polyureas (TPU) is provided. Special emphasis is given to the influence of the soft segment structure, polarity, and molecular weight, diisocyanate symmetry and the nature, extent, and strength of hydrogen bonding on the morphology and thermal and mechanical properties of TPUs. Experimental results obtained on composition-dependent TPU morphology and properties by various techniques were also compared by the morphology profiles generated by computational methods such as quantum mechanical calculations and molecular dynamics simulations.Publication Metadata only Loop-mediated isothermal amplification-integrated CRISPR methods for infectious disease diagnosis at point of care(American Chemical Society, 2023) Yetisen, Ali K.; Department of Mechanical Engineering; Yığcı, Defne; Atçeken, Nazente; Taşoğlu, Savaş; Department of Mechanical Engineering; N/A; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); KU Arçelik Research Center for Creative Industries (KUAR) / KU Arçelik Yaratıcı Endüstriler Uygulama ve Araştırma Merkezi (KUAR); School of Medicine; College of EngineeringInfectious diseases continue to pose an imminent threat to global public health, leading to high numbers of deaths every year and disproportionately impacting developing countries where access to healthcare is limited. Biological, environmental, and social phenomena, including climate change, globalization, increased population density, and social inequity, contribute to the emergence of novel communicable diseases. Rapid and accurate diagnoses of infectious diseases are essential to preventing the transmission of infectious diseases. Although some commonly used diagnostic technologies provide highly sensitive and specific measurements, limitations including the requirement for complex equipment/infrastructure and refrigeration, the need for trained personnel, long sample processing times, and high cost remain unresolved. To ensure global access to affordable diagnostic methods, loop-mediated isothermal amplification (LAMP) integrated clustered regularly interspaced short palindromic repeat (CRISPR) based pathogen detection has emerged as a promising technology. Here, LAMP-integrated CRISPR-based nucleic acid detection methods are discussed in point-of-care (PoC) pathogen detection platforms, and current limitations and future directions are also identified.