바이오이미징을 위한 생리활성감응 분자소재의 합성과 그 특성에 관한 연구

학위논문 (박사)-- 서울대학교 대학원 : 재료공학부, 2016. 8. 박수영.Bioimaging is a technique that is used for visualizing anatomical areas, as well as visualizing at the molecular level, and it is an effective tool for accurate diagnoses. For an early and accurate diagnosis, precise detection methods are necessary. To improve diagnostic selectivity and specificity, it is important to select a specific marker, which is only expressed in pathological conditions and that has changed compared to the normal biological state. It is also important to develop a probe that responds to this marker sensitively and selectively. In this thesis, various physio-responsive molecular materials are introduced as contrast agents into in the image modalities of optical imaging (fluorescence), Resonance Raman imaging and sonography in order to control for the pathology-related physio-responsive properties of material and to establish its diagnostic test accuracy thereafter. Furthermore, while utilizing the unique and beneficial properties of the newly designed probes, novel and innovative concepts are demonstrated, which can make a breakthrough for challenging issues in various bioimaging modalities. In Chapter 2, we introduce a method of a spatiotemporal detection for endogenous H2O2, which is known to cause pathological conditions, as well as fluorophores for in vivo fluorescence bioimaging. First, a reactor-like nanoassembly probe for tailoring H2O2-sensing kinetics is produced, with an H2O2-responsive fluorogenic molecule and a catalytic additive that are co-incorporated. The nanoscopic sensing kinetics are reasonably tailored over a wide range by adjusting the types and loading amounts of the catalysts. When compared to the uncatalyzed nanoprobe, the base catalysis shows an unprecedented sensing rate that is increased by ten orders of magnitude along with significantly improved H2O2 selectivity. With burst kinetics and high structural integrity, the base-catalyzed probe enables spatiotemporally resolved mapping of the low-level H2O2 that is generated at the very beginning of epidermal growth factor stimulation in A431 cells. The enzyme-like rate of sensing kinetics also allows for visualizing the subcellular responses of β-cells under lipotoxicity as well as their proliferation and autophagy, demonstrating potential as a bioprobe for studying low-level H2O2-implicated cell processes. Secondly, the utility of 1,3-bis(dicyanomethylidene)indan, which turns blue in polar media by self-deprotonation, shows potential as a minimal anionic polymethine dye for probing biomolecules in cells and in vivo through non-covalent complex formation and near-infrared fluorescence signaling. In Chapter 3, we develop a new generation of RR molecular probes to analyze and monitor the molecular content of specific cellular compartments that are related to disease and to specifically respond to ROS and generate an RR signal. First, the specific cellular compartment-targeting molecular RR probes are designed for applications in live cells. This probe shows unprecedented detection sensitivity through RR enhancement and produces spectrally distinct and intense signals. The probe also allows simultaneous mapping of macromolecules such as membranes and mitochondria in live cells. Second, we demonstrate a novel design concept for a molecular-sensing platform that specifically generates a signal by non-toxic visible laser excitation, with resonant Raman nitrile signatures (~2200 cm-1) in response to ROS. The sensing principle employs a ROS-triggered oxidative chromogenic reaction that activates resonant Raman enhancement through chemical transformation of a non-resonant hydrazo molecule into a resonant azo dye with extended p-conjugation. Experimental studies as well as DFT calculations demonstrate that this design strategy for activatable resonant Raman sensors is applicable for the selective detection of highly oxidative ROS, namely hypochlorite ions, down to 100 ppm. In Chapter 4, we adapt a non-enzymatic peroxyoxalate-based Chemiluminescence (POCL) reaction for use as an H2O2-responsive ultrasound (US) contrast agent. POCL undergoes a highly sensitive and selective CL reaction for detecting H2O2 and produces a 1,2-dioxetanedione intermediate. The intermediate decomposes into to two carbon dioxide (CO2) molecules. Researchers have demonstrated that colloidal POCL nanoreactors show enhanced CL sensitivity toward H2O2. However, in this chapter we direct our attention to the carbon dioxide byproduct as a potential core gas of microbubbles for use as an H2O2-responsive ultrasound (US) contrast agent. The oxamide-rich bPEI-oxamide nano-formulation was successfully synthesized and examined by CL in optical imaging with the formation of microbubbles under microscopic observation with intense US contrast in phantom US experiments upon addition of H2O2. The nano-formulation was administered to disease-model mice and exhibited enhanced contrast in US images.Chapter1. Introduction 1 1-1. Physicochemical changes in pathological conditions 2 1-1-1. pH 2 1-1-2. Reactive oxygen species (ROS) 5 1-2. Bioimaging modalities and its contrast agent 9 1-2-1. Fluorescence imaging 9 1-2-2. Resonance Raman imaging 15 1-2-3. Ultrasound imaging 22 1-3. Research Object 27 1-4. References 30 Chapter 2. Fluorescence Bioimaging 33 2-1. Self-Deprotonation and Colorization of 1,3-Bis(dicyanomethylidene)indan in Polar Media: A Facile Route to a Minimal Polymethine Dye for NIR Fluorescence Imaging 33 2-1-1. Introduction 33 2-1-2. Experimental 36 2-1-3. Results and Discussion 40 2-1-4. Conclusions 55 2-1-5. References 55 2-2. Fluorogenic Nanoreactor Assembly with Boosted Sensing Kinetics for Timely Imaging of Cellular Hydrogen Peroxide 58 2-2-1. Introduction 58 2-2-2. Experimental 61 2-2-3. Results and Discussion 67 2-2-4. Conclusions 84 2-2-5. References 84 Chapter 3. Resonance Raman bioimaging 88 3-1. Organelle Specific Imaging in Live Cells using Resonance Raman Probe 88 3-1-1. Introduction 88 3-1-2. Experimental 92 3-1-3. Results and Discussion 99 3-1-4. Conclusions 109 3-1-5. References 110 3-2. Chromogenesis-Based Resonance Raman Molecular Sensor for Reactive Oxygen Species 113 3-2-1. Introduction 113 3-2-2. Experimental 117 3-2-3. Results and Discussion 121 3-2-4. Conclusions 131 3-2-5. References 131 Chapter 4. Ultrasound imaging 134 4-1. Introduction 134 4-2. Experimental 138 4-3. Results and Discussion 143 4-4. Conclusions 160 4-5. References 161 Abstract in Korean 165Docto

A framework for evaluating the usability of mobile phones based on multi-level, hierarchical model of usability factors

As a mobile phone has various advanced functionalities or features, usability issues are increasingly challenging. Due to the particular characteristics of a mobile phone, typical usability evaluation methods and heuristics, most of which are relevant to a software system, might not effectively be applied to a mobile phone. Another point to consider is that usability evaluation activities should help designers find usability problems easily and produce better design solutions. To support usability practitioners of the mobile phone industry, we propose a framework for evaluating the usability of a mobile phone, based on a multi-level, hierarchical model of usability factors, in an analytic way. The model was developed on the basis of a set of collected usability problems and our previous study on a conceptual framework for identifying usability impact factors. It has multi-abstraction levels, each of which considers the usability of a mobile phone from a particular perspective. As there are goal-means relationships between adjacent levels, a range of usability issues can be interpreted in a holistic as well as diagnostic way. Another advantage is that it supports two different types of evaluation approaches: task-based and interface-based. To support both evaluation approaches, we developed four sets of checklists, each of which is concerned, respectively, with task-based evaluation and three different interface types: Logical User Interface (LUI), Physical User Interface (PUI) and Graphical User Interface (GUI). The proposed framework specifies an approach to quantifying usability so that several usability aspects are collectively measured to give a single score with the use of the checklists. A small case study was conducted in order to examine the applicability of the framework and to identify the aspects of the framework to be improved. It showed that it could be a useful tool for evaluating the usability of a mobile phone. Based on the case study, we improved the framework in order that usability practitioners can use it more easily and consistently

Laser-ablative synthesis of aggregation-induced enhanced emission luminophore dyes in aqueous solutions

International audienc

Conceptual framework and models for identifying and organizing usability impact factors of mobile phones

Usability has been regarded as a critical factor affecting the quality of mobile phones. Many studies have examined usability impact factors of mobile phones on the basis of software usability concepts. However, considering mobile phones as multi-media and information appliances, a new usability concept and associated factors should be developed. This paper proposes a conceptual framework which has five views to reflect different aspect of interactions between users and mobile phones, and from which various usability impact factor models can be derived. Five views include user view, product view, interaction view, dynamic view, and execution view. Furthermore, we developed a hierarchical model which organizes usability factors in terms of goal-means relations. Through two case studies, we could verify the usefulness of the framework and model. Lastly, we developed a set of checklists that are helpful to measure the usability of mobile phones, thereby increasing the practicality of the framework and model. Copyright the author(s) and CHISIG

Solid-State Phosphorescence-to-Fluorescence Switching in a Cyclometalated Ir(III) Complex Containing an Acid-Labile Chromophoric Ancillary Ligand: Implication for Multimodal Security Printing

In this study, we have demonstrated the reconstruction of encrypted information by employing photoluminescence spectra and lifetimes of a phosphorescent Ir­(III) complex (IrHBT). IrHBT was constructed on the basis of a heteroleptic structure comprising a fluorescent N^∧O ancillary ligand. From the viewpoint of information security, the transformation of the Ir­(III) complex between phosphorescent and fluorescent states can be encoded with chemical/photoirradiation methods. Thin polymer films (poly­(methylmethacrylate), PMMA) doped with IrHBT display long-lived emission typical of phosphorescence (λ_max = 586 nm, τ_obs = 2.90 μs). Meanwhile, exposure to HCl vapor switches the emission to fluorescence (λ_max = 514 nm, τ_obs = 1.53 ns) with drastic changes in both the photoluminescence color and lifetime. Security printing on paper impregnated with IrHBT or on a PMMA film containing IrHBT and photoacid generator (triphenylsulfonium triflate) enables the bimodal readout of photoluminescence color and lifetime

Resonance raman probes for organelle-specific labeling in live cells

Raman microspectroscopy provides for high-resolution non-invasive molecular analysis of biological samples and has a breakthrough potential for dissection of cellular molecular composition at a single organelle level. However, the potential of Raman microspectroscopy can be fully realized only when novel types of molecular probes distinguishable in the Raman spectroscopy modality are developed for labeling of specific cellular domains to guide spectrochemical spatial imaging. Here we report on the design of a next generation Raman probe, based on BlackBerry Quencher 650 compound, which provides unprecedentedly high signal intensity through the Resonance Raman (RR) enhancement mechanism. Remarkably, RR enhancement occurs with low-toxic red light, which is close to maximum transparency in the biological optical window. The utility of proposed RR probes was validated for targeting lysosomes in live cultured cells, which enabled identification and subsequent monitoring of dynamic changes in this organelle by Raman imaging.Published versio