Browsing by Author "Yoon, J."

Now showing 1 - 9 of 9

Open Access
Activatable photosensitizers: agents for selective photodynamic therapy
(Wiley-VCH Verlag, 2017) Li, X.; Kolemen, S.; Yoon, J.; Akkaya, E. U.
Recent developments in the design of bifunctional and activatable photosensitizers rejuvenate the aging field of photodynamic sensitization and photodynamic therapy. While systematic studies have uncovered new dyes that can serve as potential photosensitizers, the most promising results have come from studies aimed at gaining precise control over the location and rate of cytotoxic singlet oxygen generation. As a consequence, higher selectivities and efficiencies in photodynamic treatment protocols are now within reach. This feature article highlights the variety of approaches that have been pursued to improve photodynamic therapy and to transform simple photosensitizers into smarter theranostic agents.
Open Access
Adaptive ensemble learning with confidence bounds
(Institute of Electrical and Electronics Engineers Inc., 2017) Tekin, C.; Yoon, J.; Schaar, M. V. D.
Extracting actionable intelligence from distributed, heterogeneous, correlated, and high-dimensional data sources requires run-time processing and learning both locally and globally. In the last decade, a large number of meta-learning techniques have been proposed in which local learners make online predictions based on their locally collected data instances, and feed these predictions to an ensemble learner, which fuses them and issues a global prediction. However, most of these works do not provide performance guarantees or, when they do, these guarantees are asymptotic. None of these existing works provide confidence estimates about the issued predictions or rate of learning guarantees for the ensemble learner. In this paper, we provide a systematic ensemble learning method called Hedged Bandits, which comes with both long-run (asymptotic) and short-run (rate of learning) performance guarantees. Moreover, our approach yields performance guarantees with respect to the optimal local prediction strategy, and is also able to adapt its predictions in a data-driven manner. We illustrate the performance of Hedged Bandits in the context of medical informatics and show that it outperforms numerous online and offline ensemble learning methods.
Open Access
Adaptive ensemble learning with confidence bounds for personalized diagnosis
(AAAI Press, 2016) Tekin, Cem; Yoon, J.; Van Der Schaar, M.
With the advances in the field of medical informatics, automated clinical decision support systems are becoming the de facto standard in personalized diagnosis. In order to establish high accuracy and confidence in personalized diagnosis, massive amounts of distributed, heterogeneous, correlated and high-dimensional patient data from different sources such as wearable sensors, mobile applications, Electronic Health Record (EHR) databases etc. need to be processed. This requires learning both locally and globally due to privacy constraints and/or distributed nature of the multimodal medical data. In the last decade, a large number of meta-learning techniques have been proposed in which local learners make online predictions based on their locally-collected data instances, and feed these predictions to an ensemble learner, which fuses them and issues a global prediction. However, most of these works do not provide performance guarantees or, when they do, these guarantees are asymptotic. None of these existing works provide confidence estimates about the issued predictions or rate of learning guarantees for the ensemble learner. In this paper, we provide a systematic ensemble learning method called Hedged Bandits, which comes with both long run (asymptotic) and short run (rate of learning) performance guarantees. Moreover, we show that our proposed method outperforms all existing ensemble learning techniques, even in the presence of concept drift.
Open Access
Fluorescent chemosensors: The past, present and future
(Royal Society of Chemistry, 2017) Wu, D.; Sedgwick, A. C.; Gunnlaugsson, T.; Akkaya, E. U.; Yoon, J.; James, T. D.
Fluorescent chemosensors for ions and neutral analytes have been widely applied in many diverse fields such as biology, physiology, pharmacology, and environmental sciences. The field of fluorescent chemosensors has been in existence for about 150 years. In this time, a large range of fluorescent chemosensors have been established for the detection of biologically and/or environmentally important species. Despite the progress made in this field, several problems and challenges still exist. This tutorial review introduces the history and provides a general overview of the development in the research of fluorescent sensors, often referred to as chemosensors. This will be achieved by highlighting some pioneering and representative works from about 40 groups in the world that have made substantial contributions to this field. The basic principles involved in the design of chemosensors for specific analytes, problems and challenges in the field as well as possible future research directions are covered. The application of chemosensors in various established and emerging biotechnologies, is very bright.
Open Access
I am a professional dancer
(2023-10) Rentschler, R.; Lee, B.; Collins, Ayşe; Yoon, J.
The demand for professional recognition for artists with disability is growing. There is little research, however, on the ways in which disability arts are associated with professionalism. This study examines professionalization in disability arts by comparing it with the concept of professionalization in the arts generally. It identifies three components of professionalization in disability arts by means of a case study of an inclusive arts organization. This qualitative study entails 17 semi-structured interviews with artists, staff members, and other stakeholders both with and without disabilities. The results identify both commonalities and differences in the components of professionalization between artists with and without disability and indicate challenges to be met in improving public perceptions toward the professionalization of artists with disability.
Open Access
Imaging of intracellular singlet oxygen with bright BODIPY dyes
(Elsevier Ltd, 2021-04) Kaya, S.; Kwon, N.; Kim, G.; Bila, Jose Luis; İsmaiel, Yahya A.; Yoon, J.; Seven, Özlem; Akkaya, E.
Singlet oxygen is a cytotoxic reactive species which is involved in the photodynamic therapy of cancer. It is also known to be produced endogenously in most eukaryotic cells and implicated in many biochemical processes, including apoptotic response. We now report that Bodipy based fluorescent dyes with singlet oxygen reactive modules, signal the intracellular generation of singlet oxygen through photosensitization. We believe long wavelength probes of singlet oxygen, based on this approach will be highly valuable.
Open Access
Intracellular modulation of excited-state dynamics in a chromophore dyad: differential enhancement of photocytotoxicity targeting cancer cells
(Wiley-VCH Verlag, 2015) Kolemen, S.; Işık, M.; Kim, G. M.; Kim D.; Geng, H.; Buyuktemiz, M.; Karatas, T.; Zhang, X. F.; Dede, Y.; Yoon, J.; Akkaya, E. U.
The photosensitized generation of reactive oxygen species, and particularly of singlet oxygen [O2(a1Dg)], is the essence of photodynamic action exploited in photodynamic therapy. The ability to switch singlet oxygen generation on/off would be highly valuable, especially when it is linked to a cancer-related cellular parameter. Building on recent findings related to intersystem crossing efficiency, we designed a dimeric BODIPY dye with reduced symmetry, which is ineffective as a photosensitizer unless it is activated by a reaction with intracellular glutathione (GSH). The reaction alters the properties of both the ground and excited states, consequently enabling the efficient generation of singlet oxygen. Remarkably, the designed photosensitizer can discriminate between different concentrations of GSH in normal and cancer cells and thus remains inefficient as a photosensitizer inside a normal cell while being transformed into a lethal singlet oxygen source in cancer cells. This is the first demonstration of such a difference in the intracellular activity of a photosensitizer.
Open Access
Molecular logic gates: the past, present and future
(Royal Society of Chemistry, 2018) Erbas-Cakmak, S.; Kolemen, S.; Sedgwick, A. C.; Gunnlaugsson, T.; James, T. D.; Yoon, J.; Akkaya, E. U.
The field of molecular logic gates originated 25 years ago, when A. P. de Silva published a seminal article in Nature. Stimulated by this ground breaking research, scientists were inspired to join the race to simulate the workings of the fundamental components of integrated circuits using molecules. The rules of this game of mimicry were flexible, and have evolved and morphed over the years. This tutorial review takes a look back on and provides an overview of the birth and growth of the field of molecular logics. Spinning-off from chemosensor research, molecular logic gates quickly proved themselves to be more than intellectual exercises and are now poised for many potential practical applications. The ultimate goal of this vein of research became clearer only recently-to "boldly go where no silicon-based logic gate has gone before" and seek out a new deeper understanding of life inside tissues and cells.
Open Access
Remote-controlled release of singlet oxygen by the plasmonic heating of endoperoxide-modified gold nanorods: towards a paradigm change in photodynamic therapy
(Wiley-VCH Verlag, 2016) Kolemen, S.; Ozdemir, T.; Lee, D.; Kim, G. M.; Karatas, T.; Yoon, J.; Akkaya, E. U.
The photodynamic therapy of cancer is contingent upon the sustained generation of singlet oxygen in the tumor region. However, tumors of the most metastatic cancer types develop a region of severe hypoxia, which puts them beyond the reach of most therapeutic protocols. More troublesome, photodynamic action generates acute hypoxia as the process itself diminishes cellular oxygen reserves, which makes it a self-limiting method. Herein, we describe a new concept that could eventually lead to a change in the 100 year old paradigm of photodynamic therapy and potentially offer solutions to some of the lingering problems. When gold nanorods with tethered endoperoxides are irradiated at 808 nm, the endoperoxides undergo thermal cycloreversion, resulting in the generation of singlet oxygen. We demonstrate that the amount of singlet oxygen produced in this way is sufficient for triggering apoptosis in cell cultures. EPT sees the light: When gold nanorods with tethered endoperoxides are irradiated with near-infrared light, the endoperoxides undergo thermal cycloreversion, resulting in the generation of singlet oxygen. The amount of singlet oxygen generated by these nanocomposites is sufficient for triggering apoptosis in cell cultures.