[ES] Los nanocristales de perovskita de haluros metálicos, cuya fórmula general es ABX3 (A = Cs+, CH3NH3+, CH(NH2)2+; B = Pb+2, Sn+2; y X = Cl-, Br-, I-) son una clase de nanomateriales semiconductores que han tenido un gran impacto en fotovoltaica y en la fabricación de dispositivos emisores de luz debido a sus excelentes propiedades optoelectrónicas, entre ellas, la capacidad para transportar cargas, generar electricidad y producir luz. Aunque se trata de un área menos explorada, tienen potencial para convertirse en marcadores luminiscentes en aplicaciones biológicas por sus dimensiones nanométricas (4-15 nm) y por exhibir propiedades ópticas únicas, entre ellas: alto rendimiento cuántico de fluorescencia, espectro de emisión estrecho y posibilidad de modular su emisión en función de su tamaño y composición para obtener una amplia gama de colores en la región visible (410-700 nm), lo que los convierte en candidatos prometedores en multiplexado. Además, presentan absorción multifotónica en el cercano infrarrojo y emisión upconversion, siendo una ventaja en diagnóstico por imagen, ya que se emplea una radiación que es inocua para los tejidos, tiene mayor penetración, reduce la autofluorescencia celular y mejora la relación señal-ruido. A pesar de las excelentes propiedades ópticas de estos materiales, tienden a degradarse frente a la humedad, oxígeno, luz y alta temperatura, lo que supone una clara limitación para el desarrollo de sus aplicaciones en biosensado y diagnóstico por imagen. Durante los últimos años, los avances en los métodos de encapsulación han permitido mejorar su estabilidad frente a agentes externos, generando estructuras core-shell o integrándose en matrices de una gran variedad de materiales, entre los que se incluyen óxidos inorgánicos, polímeros u otros semiconductores. Esta tesis se ha centrado en el desarrollo de diferentes nanopartículas de perovskita estables en medio acuoso para su utilización como marcadores luminiscentes en biosensado o bioimagen in vitro. En todas las metodologías propuestas se ha pretendido que las partículas resultantes cumplan con una serie de requisitos, principalmente: tamaño nanométrico (< 200 nm), elevado rendimiento cuántico de fluorescencia, estabilidad química y estructural en tampón salino o medios de cultivo, y fácil conjugación a biorreceptores específicos. Esta tesis contribuye al avance en el desarrollo de nanomateriales luminiscentes basados en perovskitas de haluros metálicos, abordando el desafío que supone su estabilización en medio acuoso y demostrando su viabilidad en medios biológicos. Se prevé que, en un futuro, sea posible su implantación en el desarrollo de plataformas analíticas de alto rendimiento que permitan la detección y/o cuantificación óptica de analitos de interés clínico, medioambiental o alimentario en el punto de atención, cumpliendo con los criterios de rapidez, fiabilidad, facilidad de manejo y bajo coste, superando en sensibilidad y capacidad de multiplexado a los sistemas actuales, la mayoría de ellos basados en nanopartículas de oro, colorantes orgánicos o sistemas quimioluminiscentes. / [CA] Els nanocristals de perovskita d'halurs metàl·lics, amb fórmula general ABX3 (A = Cs+, CH3NH3+, CH(NH2)2+; B = Pb+2, Sn+2; y X = Cl-, Br-, I-), són una classe de nanomaterials semiconductors que han tingut un gran impacte en fotovoltaica i en la fabricació de dispositius emissors de llum a causa de les seues excel·lents propietats optoelectròniques, entre elles, la capacitat per a transportar càrregues, generar electricitat i produir llum. Encara que es tracta d'una àrea menys explorada, tenen potencial per a convertir-se en marcadors luminescents en aplicacions biològiques per les seues dimensions nanomètriques (4-15 nm) i per exhibir propietats òptiques úniques, entre elles: alt rendiment quàntic de fluorescència, espectre d'emissió estret i possibilitat de modular la seua emissió en funció de les seues dimensions i composición, de manera que es pot obtindre una àmplia gamma de colors a la regió visible (410-700 nm), la qual cosa els converteix en candidats prometedors en multiplexatge. A més, presenten absorció multifotònica en el pròxim infraroig i emissió upconversion, sent un avantatge en diagnòstic per imatge, ja que s'empra una radiació que és innòcua per als teixits, té major penetració, redueix l'autofluorescència cel·lular i millora la relació senyal-soroll. Malgrat les excel·lents propietats òptiques d'aquests materials, tendeixen a degradar-se enfront de la humitat, oxigen, llum i alta temperatura, la qual cosa suposa una clara limitació per al desenvolupament de les seues aplicacions en biosensat i diagnòstic per imatge. Durant els últims anys, els avanços en els mètodes d'encapsulació han permés millorar la seua estabilitat enfront d'agents externs, generant estructures core-shell o integrant-se en matrius d'una gran varietat de materials, entre els quals s'inclouen òxids inorgànics, polímers o altres semiconductors. Aquesta tesi s'ha centrat en el desenvolupament de diferents nanopartícules de perovskita estables al mig aquós per a la seua utilització com a marcadors luminescents en biosensat o bioimatge in vitro. En totes les metodologies proposades s'ha pretés que les partícules resultants complisquen amb una sèrie de requisits, principalment: grandària nanomètric (< 200 nm), elevat rendiment quàntic de fluorescència, estabilitat química i estructural en tampó salí o medis de cultiu, i fàcil conjugació a biorreceptors específics. Aquesta tesi contribueix a l'avanç en el desenvolupament de nanomaterials luminescents basats en perovskitas d'halurs metàl·lics, abordant el desafiament que suposa la seua estabilització al mig aquós i demostrant la seua viabilitat en mitjans biològics. Es preveu que, en un futur, siga possible la seua implantació en el desenvolupament de plataformes analítiques d'alt rendiment que permeten la detecció i/o quantificació òptica d'anàlits d'interés clínic, mediambiental o alimentari en el punt d'atenció, complint amb els criteris de rapidesa, fiabilitat, facilitat de maneig i baix cost, superant en sensibilitat i capacitat de multiplexatge als sistemes actuals, la majoria d'ells basats en nanopartícules d'or, colorants orgànics o sistemes quimioluminescents. / [EN] Metal halide perovskite nanocrystals, with the general formula ABX3 (A = Cs+, CH3NH3+, CH(NH2)2+; B = Pb+2, Sn+2; y X = Cl-, Br-, I-), constitute a new class of semiconductor nanomaterials with a significant impact on photovoltaic industry and fabrication of light-emitting devices due to their excellent optoelectronic properties, including the ability to transport charges, generate electricity and produce light. While it has not been deeply explored yet, they have the potential to become luminescent labels in biological applications, given their nanometric size (4-15 nm) and unique optical properties, such as high photoluminescence quantum yield, narrow emission spectra, and the possibility to tune their emission based on size and composition. This enables a wide color gamut in the visible region (410-700 nm), making them promising candidates in multiplexing. Moreover, perovskite nanocrystals exhibit strong multi-photon absorption properties in the near-infrared region and upconversion emission, which are an advantage for bioimaging applications since near-infrared radiation is less hazardous to living organisms, has deeper tissue penetration, reduces cellular autofluorescence and enhances signal-to-noise ratio. Despite the exceptional optical properties of perovskite nanocrystals, their potential in biosensing and bioimaging applications is hindered by their poor stability against moisture, oxygen, light and heat. To overcome these issues, in the last years, several strategies have been developed to improve their stability through the encapsulation of perovskite nanocrystals in a wide variety of protective materials, such as inorganic oxides, polymers, or semiconductors, in the form of core-shell nanoparticles or embedded in a matrix. This thesis focuses on the synthesis and stabilization of perovskite nanocrystals in aqueous environments with the aim of using them as luminescent labels in biosensing or in vitro bioimaging. Different methodologies have been employed to yield particles that meet specific requirements: nanometric size (< 200 nm), high photoluminescence quantum yield, robust chemical and structural stability in saline buffers or culture media, and facile conjugation with bioreceptors. This thesis contributes to the development of luminescent nanomaterials based on metal halide perovskite nanocrystals, facing the challenge of stabilizing them in aqueous media and testing their viability in biologic media. We envision that, in the near future, it will be possible to incorporate perovskite nanoparticles in the development of high-throughput analytical platforms for the optical detection and/or quantification of clinically, environmentally or food-related analytes at the point of care, meeting the criteria of speed, reliability, ease of use, and low cost, surpassing current systems in sensitivity and multiplexing, most of them based on gold nanoparticles, organic dyes or chemiluminescent systems. / Quiero expresar mi gratitud a Mª José Bañuls y Ángel Maquieira, por concederme la beca de formación predoctoral FPI (BES-2017-080242), asociada al proyecto de Biosensores holográficos. Prueba de concepto y demostración en aplicaciones clínicas (CTQ2016-75749-R), financiado por el Ministerio de Economía y Competitividad / Collantes Pablo, C. (2024). Síntesis, estabilización y funcionalización de nanocristales de perovskita de haluros metálicos para su empleo como reveladores y marcadores en histoquímica, cultivos celulares y biosensado [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/202615

HERCULANO. Emanuele Duarte. Óleo essencial de Eucalyptus staigeriana nanoencapsulado para utilização como conservante em alimentos. 2014. 86 f. : Dissertação (mestrado) - Universidade Federal do Ceará, centro de Ciências Agrárias, Programa de Pós-Graduação em Tecnologia de Alimentos, Fortaleza-CE, 2014 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-06-02T15:23:10Z No. of bitstreams: 1 2014_dis_edherculano.pdf: 2524611 bytes, checksum: a2bde63e81c86e10551edb1c7e551872 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-06-02T15:24:28Z (GMT) No. of bitstreams: 1 2014_dis_edherculano.pdf: 2524611 bytes, checksum: a2bde63e81c86e10551edb1c7e551872 (MD5) / Made available in DSpace on 2016-06-02T15:24:28Z (GMT). No. of bitstreams: 1 2014_dis_edherculano.pdf: 2524611 bytes, checksum: a2bde63e81c86e10551edb1c7e551872 (MD5) Previous issue date: 2014 / In this study, the Eucalyptus staigeriana essential oil (ESO) was nanoencapsulated and determined the bactericidal effect of its active principle against two strains of pathogenic mircrorganisms, as a preliminary study for use in food preservation. The process occurred by forming a nanoemulsion and spray-drying, using the cashew gum (CG) as encapsulating material. The nanoparticles were characterized by analysis of particle size distribution, zeta potential, absorption spectroscopy in the infrared Fourier transform spectroscopy (FTIR), thermal analysis (TGA/DSC), in vitro release kinetics, gas chromatography coupled to mass spectrometry (GC-MS) and stability of the encapsulated. Was also determined the Minimum Bactericidal Concentration (MBC) of nanoparticles, essential oil, and cashew gum to evaluate its antimicrobial activity against Listeria monocytogenes ATCC 19115 (Gram-positive) and Salmonella Enteritidis IAL 1132 (Gram-negative). The nanoparticles had size ranging from 27.70 ± 3.42 nm to 432.67 ± 41.47 nm in accordance with the formulation, and negatively charged surface. The presence of ESO in the nanoparticles is observed through changes in peak resolutions of the spectra obtained by FT-IR. Thermal analysis showed the main events of mass loss of the samples associated with the degradation of CG. The content of ESO nanoencapsulated varied between 4.76% and 7.12%. The increase in the proportion of CG favored the rapid release of oil in water due to the increased hydrophilic character, and enhance the ability of the nanoparticles to retain the ESO in the polymeric shell during the 365 days. The results for MBC indicated a bactericidal action of the nanoencapsulated oil, and pure oil more efficient in Gram-positive. However, the nanoparticles showed better results against Gram-negative bacteria, due to a possible synergistic effect between the CG and ESO. / Neste trabalho, o óleo essencial de Eucalyptus staigeriana (OES) foi nanoencapsulado e determinado o efeito bactericida de seu princípio ativo contra duas cepas de mircrorganismos patogênicos, como um estudo preliminar para utilização na conservação de alimentos. O processo ocorreu através da formação de uma nanoemulsão e secagem em spray-drying utilizando a goma de cajueiro (GC) como material encapsulante. As nanopartículas foram caracterizadas através das análises de tamanho e distribuição de partícula, potencial zeta, espectroscopia de absorção na região do infravermelho com transformada de Fourier (FTIR), análise térmica (TGA/DSC), cinética de liberação in vitro, cromatografia gasosa acoplada à espectrometria de massa (CG-EM) e estabilidade do encapsulado. Foi também determinada a Concentração Bactericida Mínima (CBM) das nanopartículas, do óleo essencial e da goma de cajueiro para avaliar sua ação antimicrobiana contra Listeria monocytogenes ATCC 19115 (Gram-positiva) e Salmonella Enteritidis IAL 1132 (Gram-negativa). As nanopartículas apresentaram tamanho que variaram de 27,70 ± 3,42 nm a 432,67 ± 41,47 nm, de acordo com a formulação, e a superfície carregada negativamente. A presença do OES nas nanopartículas é observada através de modificações nas resoluções de pico dos espectros obtidos por FTIR. A análise térmica evidenciou os principais eventos de perda de massa das amostras associados à degradação de GC. O teor de OES nanoencapsulado variou entre 4,76 % e 7,12 %. O aumento na proporção de GC favoreceu a uma rápida liberação do óleo em água devido ao aumento do caráter hidrofílico, além de aumentar a capacidade das nanopartículas em reter o OES no invólucro polimérico no decorrer dos 365 dias. Os resultados para CBM indicaram uma ação bactericida do óleo nanoencapsulado e do óleo puro mais eficiente na bactéria Gram-positiva. No entanto, as nanopartículas mostraram um resultado melhor contra a bactéria Gram-negativa, devido a um possível efeito sinérgico entre a GC e o OES.

The past few years have witnessed significant work being directed towards drug delivery systems with layer-by layer (LbL) technique prominently featured as one of the most sought after approach. However, majority of the studies were focused on the fabrication of microcapsules which produced numerous drawbacks resulting in reduced applicability. This has spurred research into nanocapsules which has proved to overcome most of the drawbacks that plagued microcapsules by being able to evade the reticulo-endothelial system, exhibit enhanced permeability and retention in tumours etc. The capsules fabricated by the LbL technique requires a suitable combination of cationic and anionic polyelectrolytes which ensures that it is able to effectively protect the cargo it encapsulates as well as enhance its bio-applications. With numerous advantages such as biocompatibility and biodegradability to name a few, chitosan has proved to be an ideal cationic polyelectrolyte. Thus, this thesis focuses on the various therapeutic applications of LbL fabricated chitosan based nanocapsules. The first work focuses on the targeted delivery of the somatostatin analogue, Octreotide conjugated nanocapsules to over expressed somatostatin receptors. These LbL fabricated nanocapsules composed of chitosan and dextran sulfate (CD) encapsulate the anti cancer drug, doxorubicin and are found to attain site specificity as well as enhanced anti-proliferative activity. The results indicated that the nanocapsules were biocompatible and when conjugated with octreotide was found to have an enhanced internalization into SSTR expressing cells, thereby making it a viable strategy for the treatment of tumors that has an over expression of somatostatin receptors such as pancreatic carcinoma, breast carcinoma etc. The objective of the second work was to develop an efficient drug delivery system such as CD nanocapsules for encapsulation of Ciprofloxacin in order to combat infection by Salmonella, an intracellular and intra-phagosomal pathogen. In vitro and in vivo experiments showed that this delivery system can be used effectively to clear Salmonella infection. The increased retention of ciprofloxacin in tissues delivered by CD nanocapsules as compared to the conventional delivery proved that the same therapeutic effect was obtained with reduced dosage and frequency of Ciprofloxacin administration. The third work deals with the probiotic, Saccharomyces boulardii which is found to be effective against several gastrointestinal diseases but had limited clinical application due to its sensitivity to acidic environment. However, encapsulation of S. boulardii with chitosan and dextran sulfate ensured enhanced viability and selective permeability on exposure to acidic and alkaline conditions experienced during gastro intestinal transit. The final work involves the fabrication of novel pH responsive nanocapsules composed of chitosan-heparin which facilitate the intracellular delivery of a model anti-cancer drug, doxorubicin.