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Publication Metadata only 3D printed biodegradable polyurethaneurea elastomer recapitulates skeletal muscle structure and function(American Chemical Society (ACS), 2021) Gokyer, Seyda; Berber, Emine; Vrana, Engin; Orhan, Kaan; Abou Monsef, Yanad; Guvener, Orcun; Zinnuroglu, Murat; Oto, Cagdas; Huri, Pinar Yilgor; Department of Chemistry; Department of Chemistry; Yılgör, Emel; Yılgör, İskender; Researcher; Faculty Member; Department of Chemistry; College of Sciences; College of Sciences; N/A; 24181Effective skeletal muscle tissue engineering relies on control over the scaffold architecture for providing muscle cells with the required directionality, together with a mechanical property match with the surrounding tissue. Although recent advances in 3D printing fulfill the first requirement, the available synthetic polymers either are too rigid or show unfavorable surface and degradation profiles for the latter. In addition, natural polymers that are generally used as hydrogels lack the required mechanical stability to withstand the forces exerted during muscle contraction. Therefore, one of the most important challenges in the 3D printing of soft and elastic tissues such as skeletal muscle is the limitation of the availability of elastic, durable, and biodegradable biomaterials. Herein, we have synthesized novel, biocompatible and biodegradable, elastomeric, segmented polyurethane and polyurethaneurea (TPU) copolymers which are amenable for 3D printing and show high elasticity, low modulus, controlled biodegradability, and improved wettability, compared to conventional polycaprolactone (PCL) and PCL-based TPUs. The degradation profile of the 3D printed TPU scaffold was in line with the potential tissue integration and scaffold replacement process. Even though TPU attracts macrophages in 2D configuration, its 3D printed form showed limited activated macrophage adhesion and induced muscle-like structure formation by C2C12 mouse myoblasts in vitro, while resulting in a significant increase in muscle regeneration in vivo in a tibialis anterior defect in a rat model. Effective muscle regeneration was confirmed with immunohistochemical assessment as well as evaluation of electrical activity produced by regenerated muscle by EMG analysis and its force generation via a custom-made force transducer. Micro-CT evaluation also revealed production of more muscle-like structures in the case of implantation of cell-laden 3D printed scaffolds. These results demonstrate that matching the tissue properties for a given application via use of tailor-made polymers can substantially contribute to the regenerative outcomes of 3D printed tissue engineering scaffolds.Publication Metadata only A coarse graining approach in molecular simulations: fuzzy potentials(Istanbul Technical University, 2003) Department of Chemistry; Department of Chemistry; Yurtsever, İsmail Ersin; Eşsiz, Şebnem; Faculty Member; Undergraduated Student; Department of Chemistry; College of Sciences; College of Sciences; 7129; 191615A new representation for interaction potential functions is presented. Unlike the orthodox approaches, the potential function is not a fixed function in terms of internuclear coordinates but a probabilistic one which contains information over a wide range of angular degrees of freedom. It is shown that such approaches can provide practical solutions for bulk systems of high density.Publication Open Access A near-infrared benzothiazole-based chemodosimeter for rapid and selective detection of hydrogen sulfide(Turkish Chemical Society / Türkiye Kimya Derneği, 2021) Department of Chemistry; Kölemen, Safacan; Faculty Member; Department of Chemistry; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); 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; 272051Hydrogen sulfide (H2S) is a biologically relevant gaseous molecule, which involves in a wide variety of physiological and pathological processes. Thus, detection of H2S is highly valuable in order to clarify its complex roles. In this study, a new benzothiazole-based donor-acceptor type H 2S selective chemodosimeter (HP-1) was synthesized and its H2S detection capabilities were investigated in aqueous solutions. HP-1 exhibited a red-shifted absorption signal at 530 nm and a near-infrared (NIR) fluorescence peak at 680 nm as a result of enhanced intramolecular charge transfer (ICT) in the presence of H2S, which enabled a selective and very rapid ratiometric fluorescent detection. HP-1 was also showed to be highly sensitive toward H2S with a very low limit of detection value.Publication Open Access A new type of microphotoreactor with integrated optofluidic waveguide based on solid-air nanoporous aerogels(Royal Society of Chemistry (RSC), 2018) Jonas, Alexandr; Department of Chemistry; Department of Electrical and Electronics Engineering; Department of Physics; Özbakır, Yaprak; Erkey, Can; Kiraz, Alper; PhD Student; Faculty Member; Faculty Member; Department of Chemistry; Department of Electrical and Electronics Engineering; Department of Physics; College of Engineering; College of Sciences; N/A; 29633; 22542In this study, we developed a new type of microphotoreactor based on an optofluidic waveguide with aqueous liquid core fabricated inside a nanoporous aerogel. To this end, we synthesized a hydrophobic silica aerogel monolith with a density of 0.22 g cm(-3) and a low refractive index of 1.06 that-from the optical point of view-effectively behaves like solid air. Subsequently, we drilled an L-shaped channel within the monolith that confined both the aqueous core liquid and the guided light, the latter property arising due to total internal reflection of light from the liquid-aerogel interface. We characterized the efficiency of light guiding in liquid-filled channel and-using the light delivered by waveguiding-we carried out photochemical reactions in the channel filled with aqueous solutions of methylene blue dye. We demonstrated that methylene blue could be efficiently degraded in the optofluidic photoreactor, with conversion increasing with increasing power of the incident light. The presented optofluidic microphotoreactor represents a versatile platform employing light guiding concept of conventional optical fibres for performing photochemical reactions.Publication Metadata only A novel magnetomechanical pump to actuate ferrofluids in minichannels(Begell House, Inc, 2011) Bilgin, Alp; Kurtoglu, Evrim; Erk, Hadi Cagdas; Sesen, Muhsincan; Kosar, Ali; Department of Chemistry; Acar, Havva Funda Yağcı; Faculty Member; Department of Chemistry; College of Sciences; 178902An improvement in the current methods of ferrofluid actuation was presented in this paper. A novel magnetomechanical microfluidic pump design was implemented with a ferrofluid as the active working fluid. Obtained flow rates were comparable to previous results in this research line. It was also seen that the basic pump architecture, which the subject pump is based on, enables much more room for further development.Publication Metadata only A study of the factors affecting the duration of exclusive breastfeeding(Nobel İlaç, 2009) Vehid, Hayriye Ertem; Vehid, Suphi; Gökçay, Gülbin; Bulut, Ayşen; Department of Chemistry; Haciu, Durata; Teaching Faculty; Department of Chemistry; College of Sciences; N/AObjective: This study aims to identify factors affecting the duration of exclusive breastfeeding during the first 6 months of life. Material and Method: The study was Carded out oil two groups of women, a study group of 125 women who received breastfeeding counselling voluntarily between July 2002 and June 2003, and a control group of 125 women who did not receive any counselling. Hospital interventions during delivery, sociodemographic characteristics of the mother support of the father and family members, antenatal education of the mother, are the factors evaluated for the duration of exclusive breastfeeding. The analysis was performed using the Cox regression method and significant hazard ratio values were used for analysis The data evaluated in this study was approved by the Ethical Committee of The medical Faculty of İstanbul University (Nr. 21375). Results: At 6 months of age 57.6% of the infants from, the study group and 11.2% from the control group were exclusively breastfeeding When the two groups were evaluated together the leading factor affecting the duration of exclusive breastfeeding, was found to be antenatal education (p=0.036) Within the first 6 months of life, the risk of stopping breast feeding among mothers who did not receive antenatal education is 1.67 times higher than in those who had antenatal education. Conclusion: Our findings show that, the proportion of exclusive breastfeeding was significantly high In the study group. This difference became more significant among mothers who had antenatal education oil breast-feeding in conclusion, antenatal education and breast-feeding counselling seemed to be necessary for successful breast-feeding diving the first 6 months of life.Publication Open Access A young male patient presented with dyspnea, cough, and lilateral pulmonary infiltrations: what is your siagnosis?(Aves, 2016) Department of Chemistry; İliaz, Sinem; Yurtsever, İsmail Ersin; Çağlayan, Benan Niku; Doctor; Department of Chemistry; College of Sciences; Koç University Hospital; 168584; 7129; N/APublication Open Access Activity-based photosensitizers with optimized triplet state characteristics toward cancer cell selective and image guided photodynamic therapy(American Chemical Society (ACS), 2022) Elmazoğlu, Zübeyir; Kepil, Dilay; Etienne, Thibaud; Marion, Antoine; Günbaş, Görkem; Department of Chemistry; Kılıç, Eda; Almammadov, Toghrul; Kölemen, Safacan; Researcher; Faculty Member; Department of Chemistry; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 272051Activity-based theranostic photosensitizers are highly attractive in photodynarnic therapy as they offer enhanced therapeutic outcome on cancer cells with an imaging opportunity at the same time. However, photosensitizers (PS) cores that can be easily converted to activity-based photosensitizers (aPSs) are still quite limited in the literature. In this study, we modified the dicyanomethylene-4H-chromene (DCM) core with a heavy iodine atom to get two different PSs (DCMo-I, I-DCMo-Cl) that can be further converted to aPS after simple modifications. The effect of iodine positioning on singlet oxygen generation capacity was also evaluated through computational studies. DCMo-I showed better performance in solution experiments and further proved to be a promising phototheranostic scaffold via cell culture studies. Later, a cysteine (Cys) activatable PS based on the DCMo-I core (DCMo-I-Cys) was developed, which induced selective photocytotoxicity along with a fluorescence turn-on response in Cys rich cancer cells.Publication Metadata only AFM investigation of segmented, highly branched polyurethaneureas(American Chemical Society (ACS), 2006) Fornof, Ann R.; Long, Timothy E.; Sheth, Jignesh; Wilkes, Garth L.; Department of Chemistry; Department of Chemistry; Department of Chemistry; Yılgör, İskender; Yılgör, Emel; Ünal, Serkan; Faculty Member; Researcher; Undergraduate Student; Department of Chemistry; College of Sciences; College of Sciences; College of Sciences; 24181; 40527; 241611N/APublication Metadata only An easily available lysosomal-targeted ratiometric fluorescent probe with aggregation induced emission characteristics for hydrogen polysulfide visualization in acute ulcerative colitis(Royal Society of Chemistry (RSC), 2021) Xiang, Chunbai; Li, Chunbin; Xiang, Jingjing; Luo, Yuan; Peng, Jiaofeng; Deng, Guanjun; Wang, Jianguo; Li, Hongchun; Zhang, Pengfei; Gong, Ping; Cai, Lintao; Department of Chemistry; Kölemen, Safacan; Faculty Member; Department of Chemistry; College of Sciences; 272051Hydrogen polysulfide (H2Sn, n >1), as a direct oxidizing form of hydrogen sulfide, is closely associated with intestinal diseases such as ulcerative colitis (UC). A probe that can selectively detect H2Sn in the pathological environment of UC is in urgent demand. Ratiometric probes are powerful in the quantitative detection of H2Sn in living organisms. Herein, we developed a ratiometric fluorescent probe TCFPB-H2Sn for selective detection of H(2)S(n)in vitro and in vivo. Significantly, TCFPB-H2Sn demonstrated a fast, sensitive and specific detection performance for H2Sn, and has excellent lysosomal targeting ability and aggregation-induced emission (AIE) characteristics. More importantly, TCFPB-H2Sn was the first probe to achieve endogenous H2Sn imaging in acute ulcerative colitis successfully.