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Treating global diseases is a challenging task for researchers worldwide. For successful treatment, precise diagnostics as well as efficient therapies are crucial. Both diagnostic as well as therapeutic approaches require molecular or colloidal agents to either improve resolution and contrast for imaging or improve the efficacy of a drug or delivery vehicle. A novel idea, which has been pursued for some time, is the combination of imaging and drug delivery functions in one type of nanomaterial. This new research area is referred to as theranostics – the combination of therapy and diagnostics. The presented dissertation introduces conjugated polymer nanoparticles as theranostic agents. Starting from classical dye molecules in the first chapter, croconic acid is used in combination with diamines as a basis for unprecedented conjugated polymers. The well-known concept of dispersion polymerization is utilized to synthesize croconaine-based particles in a simple way at mild reaction conditions employing easy accessible reactants. The obtained particles exhibit high photoacoustic signal. Photoacoustic imaging is a novel technique that is gaining importance in clinical applications in recent years. In addition to their good optical properties, the particles exhibit excellent biocompatibility, making them a promising material for biomedical imaging applications. Following the overall aim to develop theranostic nanoparticles, in the next chapter, particles consisting of pure imidazole polymers are established. For this synthesis, direct arylation is applied as a polycondensation. The use of this synthetic route for the preparation of conjugated polymer particles is unprecedented and provides an atom economic alternative to classical C-C coupling reactions such as Suzuki, Heck, or Sonogashira, which are commonly used for the preparation of polymer particles. Adjustment of the particle diameter is analyzed in detail, because the size of a theranostic nanomaterial is decisive with respect to the targeting strategy. Our particle diameters can be tuned between ~ 50 nm and several hundreds of nanometers. Furthermore, the variation of the type of monomer allows the design of particles composed of either linear or cross-linked polymers. This structural handle can be used for tailoring the optical properties of the particles and thus the applicability for photoacoustic or fluorescence imaging. Using nanosized materials as contrast agents has the advantage that precise and detailed visualization of the stained tissue is possible. A disadvantage is that nanoparticles can accumulate in organs and may lead to toxic effects, short-term and long-term. Therefore, the application of degradable particles may lead to better biocompatibility in the long term, while the degradable units also offer the possibility to introduce a release mechanism. Imidazole can undergo oxidative degradation when being exposed to reactive oxygen species available in the body. Therefore, the functionalization of imidazole as a degradable building block for polymers makes it possible to design π-conjugated particles that can be cleaved into small molecules in a suitable bio-microenvironment. This hypothesis is verified using the developed polyimidazole particles in detailed cell experiments. The final step to make such imidazole-based particles theranostic, is by incorporation of a suitable drug as cargo. For this aim, the anti-cancer drug lenvatinib is synthetically modified in such a way so that it becomes polymerizable. Imidazole is used as a so-called prodrug moiety, since its suitability as a degradable moiety has been verified in the previous chapter. The prodrug molecule is incorporated into imidazole polymer particles by the means of direct arylation polymerization conducted as a dispersion polymerization. Precise quantification of the release in biological environments is a difficult task, which is why we first employ standardized conditions, using hydrogen peroxide as a single reactive oxygen species to degrade the particles. The degradation products are analyzed in detail, where apart from many small degradation products of the polymer particles, lenvatinib can be detected in its active form, proving the applicability of our concept for drug delivery system.

Human exhaled breath consists of more than 3000 volatile organic compounds, many of which are relevant biomarkers for various diseases. Although gas chromatography has been the gold standard for volatile organic compound (VOC) detection in exhaled breath, recent developments in mid-infrared (MIR) laser spectroscopy have led to the promise of compact point-of-care (POC) optical instruments enabling even single breath diagnostics. In this review, we discuss the evolution of MIR sensing technologies with a special focus on photoacoustic spectroscopy, and its application in exhaled breath biomarker detection. While mid-infrared point-of-care instrumentation promises high sensitivity and inherent molecular selectivity, the lack of standardization of the various techniques has to be overcome for translating these techniques into more widespread real-time clinical use.

The multispectral modality and technique for optically dense samples of optoacoustic spectroscopy were applied to measure spectra and high absorbances of concentrated aqueous dispersions of undoped nanodiamonds. The data from optoacoustic and optical transmission measurements and DSC data of the mean particle size by the Gibbs–Kelvin equation are compared to estimate the difference in composition of various nanodiamond trademarks. Optoacoustic spectra confirm the contribution of surface dimer chains into the absorption of nanodiamonds in the long wavelength range. Optoacoustic and conventional absorption spectra of aqueous solutions of nanodiamond fractions after centrifugation (15300g) and ultracentrifugation (130000g) revealed a separation of a highly absorbing non-diamond sp2 phase. The two-step separation by ultracentrifugation followed by extra centrifugation made it possible to isolate a highly absorbing and soluble nanodiamond phase with the particle size of 3.6 nm, showing a change in spectra compared to the starting nanodiamond material. Keywords: Optoacoustic spectroscopy, Multispectral optoacoustic spectroscopy, Optically dense samples, Nanodiamonds, Nanodiamond aqueous dispersions, Nanodiamond fractionation

In the development and optimization of imaging methods, photoacoustic imaging (PAI) has become a powerful tool for preclinical biomedical diagnosis and detection of cancer. PAI probes can improve contrast and help identify pathogenic tissue. Such contrast agents must meet several requirements: they need to be biocompatible, and absorb strongly in the near-infrared (NIR) range, while relaxing the photoexcited state thermally and not radiatively. In this work, polymer nanoparticles are produced with croconaine as a monomer unit. Small molecular croconaine dyes are known to act as efficient pigments, which do not show photoluminescence. Here, for the first time croconaine copolymer nanoparticles are produced from croconic acid and a range of aromatic diamines. Following a dispersion polymerization protocol, this approach yields monodisperse particles of adjustable size. All synthesized polymers exhibit broad absorption within the NIR spectrum and therefore represent suitable candidates as contrast agents for PAI. The optical properties of these polymer particles are discussed with respect to the relation between particle size and outstanding photoacoustic performance. Biocompatibility of the polymer particles is demonstrated in cell viability experiments., publishedVersion

Review sums up the application of photoacoustic and photothermal spectroscopies for the analysis and characterization of soils and soil organic matter and discusses the outlooks in this area. Keywords: Photoacoustic spectroscopy, Optoacoustic spectroscopy, Photothermal spectroscopy, Probe microspectroscopy, Soil, Soil organic matter, Dispersed organic matter

Control over volatile products of metabolic processes in human body in exhaled air is a promising method for noninvasive medical diagnostics. The mid-IR range (2 – 12 mm) is of great interest for diagnostic applications of the exhaled air spectral analysis. Laser optoacoustic spectroscopy is quite attractive for detecting a large set of gaseous substances; however, high-power sources of tunable radiation are required to increase the method sensitivity. We consider the possibility of using a parametric light generator based on a BaGa4Se7 crystal as a broadband tunable mid-IR laser source for laser optoacoustic spectroscopy.

Agradecimentos: This work was supported by research grants SIP-IPN (20170545 and 20181764) and CONACyT (2015-02-1042, 264093, 2016-01-2482). A. M. M. acknowledges the support of the Brazilian Agencies CNPq and FAPESP. The support of COFAA-IPN by the SIBE and BEIFI programs is also acknowledged Abstract: The phase-resolved method has been widely used in photoacoustic spectroscopy for separating the contribution of different optical absorption centers to a spectrum. However, the procedure is lengthy, tedious and without precision control, because one has to calculate several spectra to search for the phase angle at which only one contribution is present every time. In this work, this limitation is avoided by the implementation of a method as a search and optimization problem using the Hill Climbing Metaheuristic Algorithm. As test examples, the photoacoustic spectra of chilli fruit skin of Anaheim type (Capsicum Annuum L.) and yellow corn grain pericarp of dent type (Zea Mays L.) were analyzed in the wavelength ranges where there is optical absorption of the photoprotective pigments of these samples CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Fechado

The cis -skew to trans -planar photoisomerization of benzil in the photoexcited state was studied by laser-induced optoacoustic spectroscopy (LIOAS) in a series of normal alkane solvents at room temperature. The structural volume change due to the photoisomerization process has been estimated and compared with the same calculated from the optimized skew and trans structures. The magnitude of the structural volume change is estimated to be 22.9 ± 1.2 mL/mol. This study reveals that an expansion in volume occurs during the photoinduced isomerization process. In non-polar alkane solvents, the estimated volume change has been argued to be free from electrostrictional contribution.

Background: Anemia is an underdiagnosed, significant public health concern afflicting >2 billion people worldwide. The detrimental effects of tissue oxygen deficiency on the cardiovascular system and concurrent appearance of anemia with numerous high-risk disorders highlight the importance of clinical screening. Currently there is no universally accepted, clinically applicable, noninvasive hemoglobin/hematocrit screening tool. The need for such a device has prompted an investigation into a breadth of techniques. Methods: A synopsis of the literature and current directions of research in noninvasive total hemoglobin measurement was collected. Contributions highlighted in this review are limited to those studies conducted with a clinical aspect, and most include in vivo patient studies. Results: The review of potential techniques presented here includes optoacoustic spectroscopy, spectrophotometric imaging, diffuse reflectance spectroscopy, transcutaneous illumination, electrical admittance plethysmography, and photoplethysmography. The technological performance, relative benefits of each approach, potential instrumentation design considerations, and future directions are discussed in each subcategory. Conclusions: Many techniques reviewed here have shown excellent accuracy, sensitivity, and specificity in measuring hemoglobin/hematocrit, thus in the near future a new clinically viable tool for noninvasive hemoglobin/hematocrit monitoring will likely be widely used for patient care. Limiting factors in clinical adoption will likely involve technology integration into the current standard of care in each field routinely dealing with anemia.

88 páginas. Doctorado en Ciencias e Ingeniería de Materiales. En el presente trabajo se planteó como objetivo general la obtención de las condiciones de depósito y la caracterización —por separado y conjuntamente— de las películas delgadas de ITO, BaTiO3, ZnO, ZnO:Mn, las cuales pueden dar lugar al desarrollo de una metodología para obtener celdas electroluminiscentes. Para esto, se realizaron varios juegos de películas delgadas por medio del depósito por láser pulsado (PLD), y para el caso particular del dopado, se empleó la variante de dos pulsos láser que inciden en distintos blancos, generando así el depósito de la película en conjunto con el dopado. En este punto es importante aclarar, que para la elaboración de la película delgada de ITO se utilizó otra técnica de depósito, ésta, conocida como erosión catódica. Cada una de las películas de ZnO y ZnO:Mn se caracterizaron por diferentes técnicas para identificar distintas propiedades. A continuación, se mencionan cada una de ellas. Rayos X: Se empleó para corroborar la cristalinidad de las películas delgadas, en donde cada película presentó una estructura tipo wurzita, orientada en los planos preferenciales (002) y (004). Perfilometria: Se midió el espesor de las películas, encontrando que todas se hallaban en el intervalo de 100 - 150 nm. EDS: Esta técnica se utilizó para conocer el porcentaje de incorporación del elemento dopante en la estructura de la película delgada. Debido a que se sabe que el depósito no es homogéneo al emplear PLD como método, se utilizó un diseño estadístico con la intensión de reducir al máximo la variabilidad. Se identificó una tendencia negativa en las películas, esto es, a mayor retraso entre láseres menor incorporación del elemento dopante. Para reconocer si las diferencias entre los promedios de incorporación eran estadísticamente significativos, se aplicó una prueba de hipótesis no paramétrica (debido a que los datos no seguían una distribución normal) y de comparaciones específicas. Fotoluminiscencia: Se realizó un barrido en el intervalo de longitud de onda de 350 - 400 nm a todas las películas delgadas, encontrado una influencia directa de la incorporación del elemento dopante respecto a la emisión de luz. Efecto Hall: Se midió la resistividad, movilidad y densidad de portadores de cada una de las películas delgadas, encontrado que éstas continuaron siendo semiconductoras independientemente del porcentaje de incorporación del elemento dopante. Espectroscopia UV - VIS: Por medio de esta técnica, se analizaron los espectros de absorción de cada una de las películas delgadas, encontrado que éste es constante en todo el intervalo. Fotoacústica: En la investigación, esta técnica de caracterización es la de mayor relevancia, ya que, a partir del empleo de la misma, es posible identificar cambios estructurales en las películas delgadas, aunque se encuentren en un porcentaje diminuto, como lo fue la detección de la fase blenda a 300 °C en las películas de ZnO, y la afectación de la incorporación del elemento dopante a dicha fase. La película delgada de BaTiO3 únicamente se caracterizó por medio de fotoacústica con la intención de localizar su temperatura de Curie, la cual se sabe se presenta a 110 °C, situación que se encontró al emplear la temperatura de 400 °C al realizar el depósito. Finalmente, se caracterizaron fotoacústicamente cada una de las multicapas que integran a la estructura electroluminiscente, esto, con la intención de conocer la influencia en los cambios estructurales al ir colocando película sobre película.

The electron-transfer reaction between the erythrosin dianion triplet, 3Er2-, and Mo(CN)84- was studied by laser-induced optoacoustic spectroscopy in the presence of various cations (Li+, Na+, K+, and Cs+, all at 4.4 × 10-2 M analytical concentration). The buffer was in each case the corresponding H3BO3/B(OH)4-,M+ (pH 9.18 at 20 °C). The enthalpy level of the triplet 3Er2- is ΔH1 = 180 ± 10 kJ mol-1 independent of the cation. The structural volume change for 3Er2- formation is ΔV1 = ca. 2 mL mol-1, attributed to intrinsic changes upon its formation. The formation of the redox products Er3- + Mo(CN)83- also leads to an expansion, ΔV2, between 12 mL mol-1 for Li+ and 8 mL mol-1 for Cs+, which linearly correlates with the heat released during the radical formation step. The correlation is interpreted in terms of an enthalpy−entropy compensation effect, due to the strong influence of the cations on the H-bond water network, also reflected in the correlation between ΔV2 and the literature values for the abilit...

Reaction volume changes, ΔVR, enthalpy content, ΔHMLCT, and decay lifetimes, τ2, of the metal-to-ligand charge transfer (MLCT) complex of (2,2‘-bipyridine)tetracyanoruthenate(II) complex, Ru(bpy)(CN)42-, inside the water pools of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles dispersed in n-alkanes, were determined using laser-induced optoacoustic spectroscopy (LIOAS). Emission quantum yields, Φem, of the complex were also determined by steady-state measurements. The enthalpy content of the MLCT state of Ru(bpy)(CN)42- was not dependent on the amount of water inside the reverse micelles (defined as the molar ratio R = [H2O]/[AOT]) and was, within experimental error, similar to that in water. However, the values of τ2 and Φem decrease while those of ΔVR increase as the values of R are incremented from 3 to 10. At the larger R values, τ2, Φem, and particularly ΔVR resemble the values in neat water. These results are interpreted to arise from the type of water involved in the hydrogen bond int...

An optoacoustic technique for solutions of strongly light-absorbing analytes at 0.1-0.01 mol l(-1) is proposed. The technique is based on the wide-band forward mode detection of temporal profiles of laser-generated ultrasonic pulses (optoacoustic signals). The leading edge of the signal repeats the distribution of the laser fluence in the medium, which makes it possible to determine its optical absorption and investigate its dynamics during a reaction. The range of light-absorption coefficients starts from 1 to 5 and reaches 10(4) to 10(5) cm(-1). The determination of iron(II) as ferroin shows the possibility of probing 0.1 mol l(-1) of iron(II), which was not previously achieved for this reaction by optical spectroscopy. To further prove the concept, kinetic measurements for ferroin decomposition at the level of 0.1 mol l(-1) and at high pHs are performed. The results are compared with spectrophotometry at lower concentrations and show good reproducibility and accuracy of kinetic constants.

Submitted by Boris Flegr (boris@uerj.br) on 2021-01-05T18:31:10Z No. of bitstreams: 1 Dissertacao Talita Zanon Guzzo BDTD.pdf: 5348333 bytes, checksum: edbf2b862952366a2c52aea31f6678e7 (MD5) Made available in DSpace on 2021-01-05T18:31:10Z (GMT). No. of bitstreams: 1 Dissertacao Talita Zanon Guzzo BDTD.pdf: 5348333 bytes, checksum: edbf2b862952366a2c52aea31f6678e7 (MD5) Previous issue date: 2010-02-23 Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro Photoacoustic spectroscopy (PAS) is a non-destructive technique and it has been largely applied to the thermal and optical characterization of materials. PAS technique is based on the photoacoustic effect which consist, basically, absorption of a modulated electromagnetic radiation and generation of heat inside of the material studied (sample), by a nonradiative deexcitation processes. Nowadays, among many PAS applications, effort are carried out to apply PAS technique for second-order phase transitions. However, only a few works can be found in the literature about glass transition studies with PAS technique. In this context, the main goal of this work is to apply PAS technique to determine glass transition temperature of the polymeric materials, based on the new photoacoustic cell configuration and on the new heating system. In this way, a photoacoustic cell was builted up for monitoring temperature variation of the sample, where the performance of the microphone was not affected. A heating system was developed based on the Peltier effect, in such way that it is possible to scan the temperature from the environment one up to 130 C, linearly at several speeds. The experimental apparatus was tested and applied to some polymeric materials: polyamide 6.0 (Nylon); polystyrene (PS-n1921 e PS-n2380); and poli(tereftalato de etileno) (PET). The results obtained were: Nylon, ; PS-n1921, ; PS-n2380, ; and PET, . These results are in a good agreement with the respective values of glass transition temperature found in the literature and show the PAS technique potentiality for glass transition studies in polymeric materials. A espectroscopia fotoacústica (PAS) é uma técnica não destrutiva e muito utilizada na caracterização óptica e térmica de materiais. Ela é baseada no efeito fotoacústico que consiste, basicamente, na absorção de onda eletromagnética modulada e na geração de calor no interior do material em estudo (amostra), via processo de desexcitação não-radiativa. Dentre as muitas aplicações relacionadas à caracterização de materiais, recentemente, a técnica PAS vem sendo desenvolvida para estudos de transição de fase de segunda ordem. Entretanto, poucos trabalhos são encontrados na literatura com relação à aplicação da técnica PAS ao estudo da transição vítrea. Neste contexto, o objetivo deste trabalho é o de aplicar a técnica PAS na determinação da temperatura de transição vítrea de materiais poliméricos, de uma maneira inovadora com relação à célula fotoacústica e ao sistema de aquecimento. Para isso foi projetada e construída uma célula fotoacústica que possibilita a variação de temperatura da amostra, sem afetar a curva de resposta do microfone. Foi desenvolvido um sistema de aquecimento baseado no efeito Peltier, possibilitando fazer rampas de subida de temperatura, com várias velocidades, da temperatura ambiente até 130 °C, de forma linear. Todo o aparato experimental foi testado e aplicado em várias amostras poliméricas: poliamida 6.0 (Nylon); poliestireno (PS-n1921 e PS-n2380); e poli(tereftalato de etileno) (PET). Os resultados obtidos foram: para o Nylon, ; para o PS-n1921, ; para o PS-n2380, ; e para o PET, . Estes resultados estão de acordo com os respectivos valores da temperatura de transição vítrea encontrados na literatura e mostram a potencialidade da técnica PAS ao estudo da transição vítrea de materiais poliméricos.

El estudio de los procesos fotofísicos primarios de colorantes en medios heterogéneos tiene gran importancia en el desarrollo de materiales fotoactivos de utilidad en diversos campos de aplicación. El creciente interés en este tipo de sistemas, en particular aquellos compuestos por colorantes incorporados a soportes sólidos, fue acompañado por el desarrollo de métodos y técnicas específicos para su caracterización. Sin embargo, debido a dificultades experimentales, no existen métodos confiables para la determinación de rendimientos cuánticos de formación de estados triplete en medios sólidos dispersores de luz. En este trabajo de Tesis se presenta un método para la determinación de dichos rendimientos basado en la aplicación de la espectroscopia optoacústica inducida por láser (LIOAS). El estudio incluye la aplicación de técnicas resueltas en el tiempo que complementan la caracterización de los estados excitados. De esta manera, la Tesis avanza sobre el conocimiento de los procesos fotofísicos primarios de colorantes adsorbidos sobre celulosa, en particular las propiedades del estado triplete de colorantes xanténicos como la Eritrosina B y el Rosa de Bengala. Los resultados obtenidos se interpretan en términos de las interacciones entre las moléculas de colorante y entre éstas y la matriz sólida. The study of primary photophysical processes of dyes in heterogeneous media is relevant to the development of photoactive materials useful in various application fields. The growing interest in such systems, particularly those composed of dyes incorporated into a solid matrix, was accompanied by the development of specific methods and techniques for their characterization. However, due to experimental difficulties, there are no reliable methods for the determination of triplet quantum yields in solid light-scattering media. In this Thesis a method for the determination of such yields based on the application of laser induced optoacoustic spectroscopy (LIOAS) is presented. The study includes the application of time-resolved techniques as a complement for the characterization of the excited states. Thus, this Thesis advances in the knowledge of primary photophysical processes for dyes adsorbed on cellulose, in particular those related to the triplet state of xanthene dyes such as Erythrosin B and Rose Bengal. Results are interpreted in terms of the interaction among dye molecules and among them and the solid matrix. Fil: Tomasini, Eugenia Paula. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

The limited penetration depth of optical energy in biological media is primarily due to the high level of optical scattering. This optical attenuation places an upper limit on optical, diagnostic, and therapeutic techniques for in in-vivo applications. The optoacoustic technique combines the unique advantages of light and sound, providing high levels of contrast, while maintaining the spatial resolution of acoustic techniques. The importance of colloidal gold solutions, as optical contrast agents in optoacoustic biomedical applications, is to increase the absorption of optical energy in areas where scattering is dominant and has prompted the study presented in this thesis on their characterization and quantification. It has been demonstrated that the acoustic transients generated from the optical irradiation are directly proportional to the wavelength dependent absorbed optical energy. Advantage has been taken of this fact to design two separate optoacoustic schemes. The first has been implemented to quantify the optical absorption, at a single laser wavelength, of spherical gold nanoparticles embedded within a medium that simulates the high scattering nature of soft tissue. The second has been designed to obtain the spectroscopic profile of such gold nanostructures. The results obtained from the optoacoustic analysis are compared to those from a reference measurement scheme, based on collimated optical transmission, which is in parallel and under the same conditions. This comparative analysis has confirmed the interest for the proposed technique of optoacoustics for laser spectroscopy of gold nanoparticles. In this thesis results obtained, for the first time, on the quantification and spectroscopic analysis of gold nanoparticles embedded in a liquid phantom using the optoacoustic technique are presented. The results have been confirmed by the reference measurement scheme and an offline commercial spectrophotometer. To further demonstrate the potential of the optoacoustic technique, information regarding the position and dimensions of the absorbing solutions have been extracted from measurements. The spectroscopic analysis has been carried out in steps of 5 nm over the complete wavelength range from 450 nm to 650 nm for a spherical gold nanoparticle solution and 410 nm to 1000 nm for a gold nanorod solution. This research work has opened up new lines of investigation in the field of monitorization of nanoparticle contrast agents embedded in biological media for optoacoustic diagnostics and biomedical applications., La limitación que existe en la profundidad de penetración de la energía óptica en medios biológicos se debe en principalmente al alto nivel de scattering (dispersión) óptico que éstos presentan. Esta atenuación óptica impone un límite superior que condiciona el uso de técnicas ópticas tanto en el campo del diagnóstico como en aplicaciones terapéuticas in vivo. La técnica optoacústica combina las ventajas que tienen la luz y el sonido, ofreciendo altos niveles de contraste, a la vez que garantiza la resolución temporal que ofrecen las técnicas acústicas. Las soluciones coloidales de oro permiten aumentar la absorción de la energía óptica. Este efecto puede ser utilizado como agente de contraste óptico en las técnicas optoacústicas donde hay medios con un alto nivel de scattering óptico. Este fenómeno ha motivado su caracterización y cuantificación en esta tesis. En esta tesis se ha demostrado que los transitorios acústicos generados a partir de la irradiación óptica son directamente proporcionales a la energía óptica absorbida y a su longitud de onda. Aprovechando este hecho, se ha diseñado dos sistemas optoacústicos. El primero se ha implementado con el objetivo de cuantificar la absorción óptica, en una única longitud de onda, de las nanopartículas esféricas de oro embebidas en un medio con alto nivel de scattering que modela las propiedades ópticas de tejidos blandos. El segundo esquema ha sido diseñado para conseguir el perfil espectroscópico de dichas nanopartículas de oro. Los resultados obtenidos del análisis optoacústico se han comparado con los resultados proporcionados por un sistema de medida de referencia, basado en la transmisión óptica, que funciona en paralelo con el sistema optoacústico y bajo las mismas condiciones experimentales. Este estudio comparativo ha confirmado el interés de las técnicas optoacústicos para aplicaciones en espectroscopia laser para nanopartículas. En este trabajo de tesis se presenta por primera vez resultados sobre la cuantificación y el análisis espectroscópico de nanopartículas de oro embebidas en un fantom liquido utilizando técnicas optoacústicos. Los resultados han sido confirmados por las medidas de referencia y también por los datos ofrecidos por un espectrofotómetro comercial. Para profundizar en el potencial de la técnica optoacústica, se ha conseguido extraer información relacionada con las dimensiones y posición de la solución absorbente partiendo de las medidas realizadas. El análisis espectroscópico se ha llevado a cabo realizando adquisiciones en pasos de 5 nm a lo largo del rango de longitudes de onda que va desde los 450 nm hasta los 650 nm para nanopartículas esféricas y en el rango que se extiende entre los 410 nm y los 1000 nm para la solución de nanorods de oro en un medio de alto nivel de scattering óptico. Este trabajo de tesis doctoral ha abierto nuevas líneas de investigación en el campo de la monitorización de nanopartículas como agentes de contraste óptico embebidos en medios biológicos para el diagnóstico mediante técnicas optoacústicos y aplicaciones biomédicas.

Oxidative-based diseases including diabetes, chronic renal failure, cardiovascular diseases and neurological disorders are accompanied by accumulation of advanced glycation endproducts (AGE). Therefore, AGE-associated changes in tissue optical properties could yield a viable pathological indicator for disease diagnostics and monitoring. We investigated whether skin glycation could be detected based on absorption changes associated with AGE accumulation using spectral optoacoustic measurements and interrogated the optimal spectral band for skin glycation determination. Glycated and non-glycated skin was optoacoustically measured at multiple wavelengths in the visible region. The detected signals were spectrally processed and compared to measurements of skin auto-fluorescence and to second harmonic generation multiphoton microscopy images. Optoacoustic measurements are shown to be capable of detecting skin glycolysis based on AGE detection. A linear dependence was observed between optoacoustic intensity and the progression of skin glycation. The findings where corroborated by autofluorescence observations. Detection sensitivity is enhanced by observing normalised tissue spectra. This result points to a ratiometric method for skin glycation detection, specifically at 540 nm and 620 nm. We demonstrate that optoacoustic spectroscopy could be employed to detect AGE accumulation, and possibly can be employed as a non-invasive quick method for monitoring tissue glycation.

The volume changes accompanying triplet state formation, decay and quenching in aqueous solution were followed by temperature-dependent, laser-induced, optoacoustic spectroscopy (LIOAS) measurements. The origin of these volume changes mainly involves specific solvent-solute interactions, which are different in the triplet state than in the parent ground state.

In this work we present results of an investigation on Doppler limited infrared absorbing transitions of CHD2OH by optoacoustic detection. It is an alternative and attractive technique to be applied to this methanol isotopomer, in comparison to Fourier transform spectroscopy. Using a waveguide CO2 laser of 290 MHz tunability on each line, we were able to observe 60 IR absorptions, most of them of large offset. The data will be useful in the theoretical analysis of this molecule, as well as in the generation of far-infrared (FIR) laser radiation in optically pumped molecular lasers FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Fechado

We investigated the behavior of infrared (IR) absorption laser transitions of methanol isotopes in the presence of an uniform electric field, in order to determine Doppler-free spectroscopic data such as homogeneous linewidth and saturation parameter. For this we combine photoacoustic detection with the high resolution provided by the Nonlinear Hanle Effect (NLHE) on molecular transitions FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ Fechado

Agradecimentos: Work supported by: FAPESP, CNPq, FBB, FAEP-Brasil Abstract: In this work we present results of an investigation on Doppler limited infrared absorbing transitions of CHD2OH by optoacoustic detection. It is an alternative and attractive technique to be applied to this methanol isotopomer, in comparison to Fourier transform spectroscopy. Using a waveguide CO2 laser of 290 MHz tunability on each line, we were able to observe 60 IR absorptions, most of them of large offset. The data will be useful in the theoretical analysis of this molecule, as well as in the generation of far-infrared (FIR) laser radiation in optically pumped molecular lasers FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ Fechado

The value of optoacoustic spectroscopy as a technique for the quantitative non-destructive determination of thickness of surface layers is examined by reference to two systems. In one, carbon deposits on a nickel-alumina catalyst with graphite filler, it is shown that the deposit can be detected, and its thickness estimated by application of a simple equation. The relationship does not hold for different thicknesses of the transparent polymer melinex above 40 μm. It is argued that because the optoacoustic signal has complex origins, reliable quantitative relationships are difficult to establish. However, it is confirmed that qualitative analysis of subcutaneous layers by OAS, is relatively straightforward.

Optoacoustic (OA) detection apparatus can be used for analysis of various optical absorbers in very dilute concentrations. Parameters of pulse OA spectroscopy as applied to highly transparent samples are derived allowing to compare the potentialities to these of conventional absorption methods. We consider a frequently used OA device based upon linear thermoelastic OA conversion. Practice of both amplitude and dynamic versions of OA method are discussed. The role of pure solvent contribution is revealed. Useful estimates are provided.

Molecular spectroscopists have studied the absorption of optical radiation for over 100 years, but only in the last five years have experiments come forth on the subsequent relaxation of the molecular excitation to produce heat. By detecting this heat as an acoustic pulse using sensitive microphones and bolometers, the eventual fate of absorbed photons can be followed, both energetically and kinetically. Several examples of the unique information derived from this acoustic method of molecular spectroscopy will be presented.

A method and apparatus that significantly increases the sensitivity and flexibility of laser optoacoustic spectroscopy, with reduced size. With the method, it no longer is necessary to limit the use of laser optoacoustic spectroscopy to species whose absorption must match available laser radiation. Instead, "doping" with a relatively small amount of an optically absorbing gas yields optoacoustic signatures of nonabsorbing materials (gases, liquids, solids, and aerosols), thus significantly increasing the sensitivity and flexibility of optoacoustic spectroscopy. Several applications of this method are demonstated and/or suggested.