The ability to monitor the presence of analytes is of great importance both in industrial applications and physiological systems. Since the crucial recognition events of chemistry, biology, and materials science occur in a much smaller world, it is very difficult to gather this kind of information. Therefore much effort has been devoted to the detection of chosen molecules selectively and signalling this presence. This thesis highlighted the uniqueness and utility of both fluorescent sensor and electrochemical sensor to investigate biologically important species. The determination of copper(II) ion is very crucial to both environment and human health. To utilise the fluorescent sensors for recognition has plenty of advantages, such as high sensitivity, “on-off” switch ability and submillisecond temporal resolution. Naphthalimide based probes has always been the key point of the chemosensors due to its excellent photophysical properties. Therefore, the aim of the project is to investigate boronic acid receptor linked to the naphthalimide fluorophore for copper(II) detection. And the utility of boronic acid as binding site is one of the rare examples of fluorescent chemosensors for Cu2+ detection. Neutral molecules such as glutathione (GSH) play a crucial role in maintaining appropriate redox homeostasis in biological systems. We creatively use the chromophore of dicyanomethylene-4H-pyran(DCM) for the design of probe, due to its emission located at the red or near infra-red (NIR) region, which is particularly suitable for application in biological samples. GSH, the most abundant cellular thiol, is of great importance in cellular defence against toxins and free radicals. Therefore we developed a colorimetric and NIR fluorescence turn-on thiol probe containing DCM as the fluorophore and DNBS as the fluorescence quencher and recognition moiety. The interaction of ferrocene-boronic acid with fructose is investigated in aqueous 0.1 M phosphate buffer at pH 7, 8, and 9. Two voltammetric methods, (i) based on a dual-plate generator-collector micro-trench electrode (steady state) and (ii) based on square-wave voltammetry (transient), are applied and compared in terms of mechanistic resolution. A combination of experimental data is employed to obtain new insights into the binding rates and the cumulative binding constants for both the reduced ferrocene-boronic acid (pH dependent and weakly binding) and for the oxidised ferrocene-boronic acid (pH independent and strongly binding). Finally, a redox-activated fluorescence switch based on a ferrocene - fluorophore - boronic ester conjugate was investigated. The development of multifunctional systems that can integrate individual basic logic gates into combinational circuits has drawn much attention to smart materials. A novel electrochemically and fluorescence active boronic ester sensor molecule has been developed containing ferrocence and naphthalimide as the redox and fluorophore units. The solid state electrochemical characterisation of the compound was investigated in aqueous media and it indicates a direct interaction with fluoride anions. The fluorescence can also be modulated through photoinduced electron transfer (PET) by a redox process. An OFF-ON fluorescence response occurs when the ferrocene is oxidised by Fe3+. While in the presence of F-, the fluorescence enhancement was offset. Therefore, the combinations of iron (Fe3+ ) ions, sodium L-ascorbate, and fluoride (F-) ions can be used to produce a molecular system displaying INHIBIT logic gate, due to indirect fluorescence quenching.

Bacterial infections are and likely always will be a serious and costly complication to treatment in a healthcare environment. However consistent rises in the number of both healthcare associated and antibiotic resistant infections over the last of decades has the potential to turn a serious problem into a catastrophe. Control of infections in hospital wards has improved over the last five years but data from the European Centre for Disease Prevention and Control suggests a stale mate. While the numerical rise in drug resistant organisms has slowed, the severity of drug resistance appears to be on the increase with the prolific emergence of multiple drug resistant isolates. On the front lines of the threat that these organisms represent are some of the most susceptible. In hospitals those who are already sick are more vulnerable, those with co-morbidities, those with surgical or other wounds, the very old and the very young. Children especially show high susceptibility as they are often incapable of communicating clinical complications in the way an adult might. This coupled with higher commonality of specific aetiologies in children such as scalds, open wounds that are prone to infection without proper treatment, creates population in need. Antibiotics are often thought to be part of the problem in drug resistance, indeed to an extent they are. However their real downfall may be improper use. In order to improve treatment outcomes and simultaneously decrease antimicrobial resistance a combination of rapid diagnosis and prophylaxis can be utilised to decrease selection of resistance. As such, this study focuses on the development of a novel vesicle based sensor system for the detection of bacterial infections in burn wounds. Additionally an organometallic antimicrobial system has been developed with the potential for surface attachment. Work with the vesicle based biosensor demonstrates high sensitivity to both Staphylococcus aureus and Pseudomonas aeruginosa. The toxins involved in activation of the sensor have been determined in both cases and an in-depth study into the activity of the staphylococcal agents of lysis (Phenol Soluble Modulins and delta haemolysin), shows a high degree of plasticity and tunability in the sensors function. Work with the zinc based antimicrobial reveals a highly complex system which demonstrates possible functions as a not only an antimicrobial but as a sensor system in its own right.

Chemical sensors capable of detecting a specific atom or molecule under various conditions have been utilized in biological and environmental analyses. Fluorescence based sensors are particularly advantageous in these studies because of their high sensitivity, relative ease in handling, and low technical costs. This dissertation focuses on the detection of two analytes, H+ and hypochlorous acid, which are of interest in biology because the presence of abnormal quantities of these analytes may be indicative of disease. We have established a new platform for which sensitive changes in various regions of pH can be detected using fluorescence. The aminomethylrhodamine (AMR) scaffold is highly versatile, i.e. the pH range in which the sensor is active can be tuned by introducing different substituents on the amine moiety. Overall this systematic approach to the design of pH sensitive fluorophores has allowed for a library of compounds that are responsive over a broad range of pH (pH 3 - 10) by simply changing the substituent on the amino group. We report the synthesis and characterization of a silicon analog of rhodamine for the fluorescence based detection of hypochlorous acid. This fluorophore exhibits a 90 nm bathochromic shift in its absorption and emission, relative to its oxygen counterpart. Hypochlorous acid is a biological agent linked to certain diseases. Therefore, the longer wavelength properties of the this far-red fluorescent sensor will be of significant benefit to imaging experiments of this analyte in biological media and tissue due to its spectral proximity of the so called NIR optical window. Furthermore, the novel synthetic methodology of this sensor possesses a key intermediate, which could potentially lead to future fluorescence based sensors. The characterization of a fluorescent probe designed for the detection of hypochlorous acid (HOCl) using a silicon analog of fluorescein (SiF) was also reported. Over a range of pHs, the probe reacts with a stoichiometric amount of HOCl resulting in a mixture of two pH dependent fluorescent species, a SiF disulfide product and a SiF sulfonate product. The unique colorometric properties of the individual SiF fluorophores were utilized to perform simultaneous detection of HOCl and pH. When an excess of HOCl is present, the SiF fluorophores become chlorinated, via an intermediate halohydrin, resulting in a more pH independent and red-shifted fluorophore. Finally, an attempt was made at developing a pH responsive photodynamic therapy agent. This system was designed to target the relatively low extracellular pH found around tumors. A di-bromohydroxymethylrhodamine system was synthesized and the photophysical properties were characterized. This system absorbs weakly under acidic conditions (ca. pH 3), however was shown to be a moderate photosensitizer under acidic conditions.

In the first study, a new µ-HPLC column was developed using a monolithic silica gel as a column substrate for chiral separation by covalently modifying with (S, S)-Whelk-O1 chiral selector. The monolithic stationary phase was generated through a sol-gel process and prepared in situ in a 100 µm i.d. fused silica capillary tubing. The chromatographic performance was characterized in terms of retention factor, column efficiency, enantioselectivity and resolution, as well as the kinetics parameters affecting the separation. Comparison with a commercial particle packed HPLC column demonstrates a promising enantioselective resolving ability of the monolithic Whelk-O1 capillary column. The second project focuses on characterization of fluorescent sensor for zinc detection. In this work, we have examined the photophysical properties of the fluorescent probe sensor that has been developed in our laboratory for Zn2+ recognition via a photo-induced electron transfer (PET) sensing mechanism. To characterize the fundamental function of sensor, response curves have been conducted, using acetone/methanol (199:1), 1,4-dioxane, acetone, methanol and aqueous buffer as the solvent system. Similar to prior work from our group, the sensor was found to respond selectively to Zn2+ ions with fluorescence enhancement. The fluorescence properties and binding response were evaluated in the presence of water and a Lewis base, which we found to have a marked effect on the fluorescence signal. The selectivity of the sensor for Zn2+ was also observed and compared to other divalent metal such as Ca2+, Mg2+, Cu2+ and Hg2+ with the goal of learning fundamental information on the system that can aid in the development of future PET based sensors.

No description available.

The main theme of this thesis is to develop a fluorescent probe for imaging the subcellular distribution of kinetically labile copper pools that might play a critical role in copper homeostasis. Various copper-selective sensors were designed by combining 1,3,5-triaryl-2-pyrazoline fluorophores with polythioethers as receptor moieties. A series of donor-substituted 1,3,5-triaryl-2-pyrazoline fluorophores were synthesized and characterized in terms of their photophysical and electrochemical properties. Interestingly, the aryl substituents attached to the 1- and 3-position of the pyrazoline ring influence the photophysical properties of the fluorophore in distinctly different ways. The excited-state equilibrium energy is primarily influenced by changes of the substituent in the 1-position, whereas the reduction potential of the fluorophore is determined by the 3-aryl group. Results from computational analyses agree well with the experimental data. A pyrazoline fluorophore library was synthesized, and their photophysical and electrochemical properties were studied. The compounds cover a broad range of excited state energies and reduction potentials, and allow for selective and differential tuning of these two parameters. A series of thiazacrownethers and tripodal aniline copper(I) receptors were synthesized and their copper binding stoichiometries, stability constants, and copper-self-exchange kinetics were investigated. The measured self-exchange activation parameters revealed for all studied ligands a negative activation entropy, suggesting a predominant associative exchange mechanism. With detailed knowledge of the fluorophore platform and copper receptors, sensor CTAP-1 was designed, synthesized and characterized. The probe shows a 4.6-fold emission enhancement and reaches a quantum yield of 14% upon saturation with Cu(I). The sensor exhibits excellent selectivity towards Cu(I) and is insensitive towards millimolar concentrations of Mg(II) or Ca(II). Mouse fibroblast cells (3T3) incubated with the sensor produced a copper-dependent perinuclear staining pattern, which colocalizes with the subcellular location of the mitochondria and the Golgi apparatus. The subcellular topography of copper was further determined by synchrotron-based x-ray fluorescence (SXRF) microscopy. Furthermore, microprobe x-ray absorption measurements at various subcellular locations showed a near-edge feature that is characteristic for low-coordinate monovalent copper. The data provide a coherent picture with evidence for a kinetically labile copper pool, which is predominantly localized in the mitochondria and the Golgi apparatus.

La conception, la synthèse et l’étude des propriétés photophysiques de sondes fluorescentes d’espèces moléculaires ou de cations présente beaucoup d’intérêt dans des domaines aussi divers que l’environnement et la biologie. En particulier, les cations polluants (cations d’aluminium, cations de potassium) et les résidus de pesticides (tels que le glyphosate ou l’atrazine) qui n’étant pas dégradés par le métabolisme, ils se retrouvent dans les eaux de boissons à des concentrations délétères pour l’environnement. Les méthodes analytiques actuelles telles que la spectroscopie d'absorption atomique, la spectroscopie de masse sont coûteuses et ne peuvent être utilisées que pour les déterminations à l'intérieur. Inversement, l'utilisation de la technique de fluorescence offre des avantages distincts en termes de sensibilité, de sélectivité et de développement potentiel d'appareils portables.Dans cette thèse, des sondes fluorescentes efficaces pour la détection de l'aluminium, du potassium, du glyphosate et de l'atrazine ont été ciblées. Pour l'aluminium, une nouvelle sonde hydrosoluble (PSSA) a été synthétisée, reconnaissant les cations d'aluminium sur la base du mécanisme d'amélioration de l'émission induisant une agrégation. Avec une limite de détection de 153 nM et une bonne propriété de sélectivité, le PSSA a également été intégré avec succès dans un système PDMS / verre afin de permettre l’utilisation d’un dispositif portable pour la détection de l’aluminium.Ensuite, deux sondes synthétisées différentes de notre laboratoire (Calix-Rhod-aza et DMAP-BARB) ont été considérées dans cette thèse. Ces sondes ont été développées pour la détection de potassium et d'atrazine, respectivement. Pour les deux molécules, la photophysique et la complexation vis-à-vis d'espèces ciblées ont été étudiées, et deux configurations différentes de microfluidique capillaire en PTFE ont été réalisées pour leur détection, avec des limites de détection très satisfaisantes (qui bien conformes à la gamme des normes réglementaires).Enfin, des efforts ont été consacrés à la conception et à la synthèse de nouveaux capteurs pour le glyphosate. Quatre sondes différentes ont été conçues (GlyP-a, GlyP-b, GlyP-c, GlyP-d). GlyP-a a été faite, alors que les autres étaient à deux pas de la réalisation. En effet, ce projet est toujours en cours dans notre laboratoire, en prenant les résultats préliminaires de ce travail. / The design, synthesis and photophysical studies of fluorescent sensors of neutral molecules or cations are of great interest in environment and biology. In particular, metal-based pollutants (aluminium cations, potassium cations) and pesticide residues (such as glyphosate or atrazine) which are not degraded by the metabolism can be found in drinking water at harmful concentrations to the environment. Actual analytical methods such as atomic absorption spectroscopy, mass spectroscopy are expensive and can only be used for indoor determinations. Conversely, the use of fluorescence technique offers distinct advantages in terms of sensitivity, selectivity with a potential development of portable devices.In this thesis, efficient fluorescent probes for the sensing of aluminium, potassium, glyphosate and atrazine were targeted. For aluminium, a novel water-soluble probe (PSSA) was synthesized, which recognize aluminium cations based on aggregation-induce emission enhancement mechanism. With a detection limit of 153 nM and good selectivity property, PSSA was also successfully incorporated onto a PDMS/glass system for enabling a portable device for aluminium detection.Next, two different synthesized probes from our laboratory (Calix-Rhod-aza and DMAP-BARB) were considered in this thesis. These probes were developed for potassium and atrazine sensing, respectively. For both molecules, the photophysical and complexation towards targeted species were studied, and two different PTFE capillary microfluidics set-ups were realized for their detection, with highly satisfactorily detection limits (well in accordance with the range of the regulation standards).Finally, efforts were given on the design and synthesis of new sensors for glyphosate. Four different probes were designed (GlyP-a, GlyP-b, GlyP-c, GlyP-d). GlyP-a has been made, while the others were just one step away from realization. Indeed, this project is still under progress in our laboratory, taking the preliminary results from this work.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第20482号 / エネ博第351号 / 新制||エネ||70(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授 森井 孝, 教授 木下 正弘, 教授 片平 正人 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

No description available.

This thesis deals with the problematice of measuring membrane potential and monitoring the propagation of electrical activity of cells. For this purpose, fluorescence membrane voltage sensors have been developed to detect changes in the membrane potential by changing their fluorescence intensity. The practical part is focused on the study of the properties of the ASAP1 fluorescence probe, which was transfected into the HEK293 cell line, which are kidney cells from the human embryo. Cell membrane potential was changed using the patch-clamp technique.