Optoelectronic properties of Quantum Dots for biomedicine and energy-to-light conversion

En les últimes dècades, la nanociència ha sorgit com una nova tecnologia gràcies a la seva versatilitat per ser emprada en diferents camps. Dins d’aquets grup, un dels nanomaterials més prometedors, els punts quàntics han estat estudiats per la seva extraordinària propietats i la seva versatilitat per utilitzar-los en diferents camps. La present tesis doctoral es centra en la síntesi de diferents punts quàntics, així com en el seu ús en LEDs, cèl·lules solars perovskites i biosensors. S'han sintetitzat tres tipus de punts quàntics: cadmi, perovskites i punts quàntics de carboni. Els dos primers presenten una banda d’emissió estreta i un rendiment quàntic elevat. No obstant, la seva alta toxicitat és un inconvenient que s’ha de tenir en comte. Com alternativa al seu ús, hem sintetitzat punts quàntics fet de carboni. La seva baixa toxicitat i biocompatibilitat és una bona alternativa als nanomaterials que contenen metalls pesants. A més, el material basat en carboni es pot preparar amb productes comuns com ara glucosa o sucrosa i poden ser dissolts en dissolvents no clorats com ara l’etanol o l’aigua. El treball presentat en aquesta tesis es va dur a terme a l'Institut d'Investigació Química de Catalunya (ICIQ) i al centre tecnològic Eurecat de Catalunya, entre març de 2015 i març de 2019.En la última década, la nanociencia se ha convertido en una tecnología novedosa debido a su versatilidad para ser empleada en muchas áreas de investigación. Uno de los nanomateriales más prometedores, los puntos cuánticos coloidales, han sido estudiados en profundidad por su extraordinario optoelectrónico y su versatilidad para usar en diferentes campos. La presente tesis se centra en la síntesis de diferentes puntos cuánticos, así como su uso en LED, células solares de perovskita y biosensores. Se han sintetizado tres puntos cuánticos diferentes: cadmio, perovskita y puntos cuánticos de carbono. Los dos primeros materiales presentan un alto rendimiento cuántico y banda de emisión estrecha. Sin embargo, su alta toxicidad es una inconveniente que se tiene que tener en cuenta. Como alternativa a su uso, sintetizamos puntos cuánticos de carbono. Su baja toxicidad y su biocompatibilidad es una buena alternativa a los nanomateriales que contienen metales pesados. Además, el material a base de carbono se puede preparar utilizando productos de uso diario como azúcar o jugo de naranja y se puede resolver en solventes que no sean de cloro, como etanol o agua. El trabajo presentado en esta tesis se llevó a cabo en el Instituto de Investigación Química de Cataluña (ICIQ) y en Eurecat, el centro tecnológico de Cataluña, entre marzo de 2015 y marzo de 2019.In the last decades, nanoscience has emerged as a novel technology due to its versatility to be employed in many research areas. One of the most promising nanomaterials, colloidal quantum dots have been deeply studied for their extraordinary optoelectronic properties and their versatility in order to use in different fields. The present thesis is focused on the synthesis of different quantum dots as well as their use in LEDs, perovskites solar cells and biosensors. Three different Quantum Dots have been synthetized: cadmium, perovskites and carbon based quantum dots. The first two material present a high quantum yield and narrow emission band. However, their high toxicity is an important drawback. In order to avoid the use of those material we synthetized carbon quantum dots. Their low toxicity and biocompatibility is a good alternative to heavy metal-containing nanomaterials. In addition, carbon based material can be prepared using ordinary products as glucose or sucrose and solved in non-chloro solvents such as ethanol or water. The work discussed in this thesis was carried out at Institute of Chemical Research of Catalonia (ICIQ) and Eurecat the technological center of Catalonia, between March 2015 and March 2019

Recent progress in biomedical sensors based on conducting polymer hydrogels

Biosensors are increasingly taking a more active role in health science. The current needs for the constant monitoring of biomedical signals, as well as the growing spending on public health, make it necessary to search for materials with a combination of properties such as biocompatibility, electroactivity, resorption, and high selectivity to certain bioanalytes. Conducting polymer hydrogels seem to be a very promising materials, since they present many of the necessary properties to be used as biosensors. Furthermore, their properties can be shaped and enhanced by designing conductive polymer hydrogel-based composites with more specific functionalities depending on the end application. This work will review the recent state of the art of different biological hydrogels for biosensor applications, discuss the properties of the different components alone and in combination, and reveal their high potential as candidate materials in the fabrication of all-organic diagnostic, wearable, and implantable sensor devices.Peer ReviewedPostprint (published version

PLA-PEG-Cholesterol biomimetic membrane for electrochemical sensing of antioxidants

Polymeric membranes exhibit unique and modulate transport properties when they are properly functionalised, which make them ideal for ions transport, molecules separation and molecules interactions. The present work proposes the design and fabrication of nanostructured membranes, composed by biodegradable poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG), incorporating a lipophilic molecule (cholesterol) covalently bonded, were especially designed to provide even more application opportunities in sensors field. Electrochemical studies, by means of electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and square wave voltammetry (SWV), revealed important differences regarding the functionalised and non-functionalised PLA systems. PEG-cholesterol building block units showed a clear affinity with ascorbic acid (vitamin C) and Trolox® (a water-soluble analogue of vitamin E), both hydrophilic in nature, with a limit of detection capacity of 8.12 µM for AA and 3.53 µM for AA and Trolox, respectively, in aqueous salt solution. The bioinspired polymer may be used to incorporate antioxidant property that allow the design of anti-stress biosensors, electrodes for the detection of vitamin C or vitamin E in biomedical nutrition programs, among other applications.The authors thank the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement BioInspireSensing No 955643 for supporting this work. Authors also acknowledge the Agència de Gestió d'Ajuts Universitaris i de Recerca, AGAUR (Grant number: 2021 SGR 00387), by Generalitat de Catalunya (Spain), for the financial support of this research.Peer ReviewedPostprint (published version

Optoelectronic properties of Quantum Dots for biomedicine and energy-to-light conversion

En les últimes dècades, la nanociència ha sorgit com una nova tecnologia gràcies a la seva versatilitat per ser emprada en diferents camps. Dins d’aquets grup, un dels nanomaterials més prometedors, els punts quàntics han estat estudiats per la seva extraordinària propietats i la seva versatilitat per utilitzar-los en diferents camps. La present tesis doctoral es centra en la síntesi de diferents punts quàntics, així com en el seu ús en LEDs, cèl·lules solars perovskites i biosensors. S'han sintetitzat tres tipus de punts quàntics: cadmi, perovskites i punts quàntics de carboni. Els dos primers presenten una banda d’emissió estreta i un rendiment quàntic elevat. No obstant, la seva alta toxicitat és un inconvenient que s’ha de tenir en comte. Com alternativa al seu ús, hem sintetitzat punts quàntics fet de carboni. La seva baixa toxicitat i biocompatibilitat és una bona alternativa als nanomaterials que contenen metalls pesants. A més, el material basat en carboni es pot preparar amb productes comuns com ara glucosa o sucrosa i poden ser dissolts en dissolvents no clorats com ara l’etanol o l’aigua. El treball presentat en aquesta tesis es va dur a terme a l'Institut d'Investigació Química de Catalunya (ICIQ) i al centre tecnològic Eurecat de Catalunya, entre març de 2015 i març de 2019.En la última década, la nanociencia se ha convertido en una tecnología novedosa debido a su versatilidad para ser empleada en muchas áreas de investigación. Uno de los nanomateriales más prometedores, los puntos cuánticos coloidales, han sido estudiados en profundidad por su extraordinario optoelectrónico y su versatilidad para usar en diferentes campos. La presente tesis se centra en la síntesis de diferentes puntos cuánticos, así como su uso en LED, células solares de perovskita y biosensores. Se han sintetizado tres puntos cuánticos diferentes: cadmio, perovskita y puntos cuánticos de carbono. Los dos primeros materiales presentan un alto rendimiento cuántico y banda de emisión estrecha. Sin embargo, su alta toxicidad es una inconveniente que se tiene que tener en cuenta. Como alternativa a su uso, sintetizamos puntos cuánticos de carbono. Su baja toxicidad y su biocompatibilidad es una buena alternativa a los nanomateriales que contienen metales pesados. Además, el material a base de carbono se puede preparar utilizando productos de uso diario como azúcar o jugo de naranja y se puede resolver en solventes que no sean de cloro, como etanol o agua. El trabajo presentado en esta tesis se llevó a cabo en el Instituto de Investigación Química de Cataluña (ICIQ) y en Eurecat, el centro tecnológico de Cataluña, entre marzo de 2015 y marzo de 2019.In the last decades, nanoscience has emerged as a novel technology due to its versatility to be employed in many research areas. One of the most promising nanomaterials, colloidal quantum dots have been deeply studied for their extraordinary optoelectronic properties and their versatility in order to use in different fields. The present thesis is focused on the synthesis of different quantum dots as well as their use in LEDs, perovskites solar cells and biosensors. Three different Quantum Dots have been synthetized: cadmium, perovskites and carbon based quantum dots. The first two material present a high quantum yield and narrow emission band. However, their high toxicity is an important drawback. In order to avoid the use of those material we synthetized carbon quantum dots. Their low toxicity and biocompatibility is a good alternative to heavy metal-containing nanomaterials. In addition, carbon based material can be prepared using ordinary products as glucose or sucrose and solved in non-chloro solvents such as ethanol or water. The work discussed in this thesis was carried out at Institute of Chemical Research of Catalonia (ICIQ) and Eurecat the technological center of Catalonia, between March 2015 and March 2019

Direct White Light Emission from Carbon Nanodots (C-dots) in solution processed Light Emitting Diodes

We describe the preparation of inverted white light emitting diodes by solution processing. The active layer is formed uniquely by Carbon Nanodots (C-dots) that display white-light emission at voltage close to 5V when combined with metal oxides as charge transport layers. Moreover, we have demonstrated that the white light is not the product of charge transfer between the polymer selective contact and the C-dots but the result of the different recombination processes within the C-dots

Advances in Functionalization of Bioresorbable Nanomembranes and Nanoparticles for Their Use in Biomedicine

Bioresorbable nanomembranes (NMs) and nanoparticles (NPs) are powerful polymeric materials playing an important role in biomedicine, as they can effectively reduce infections and inflammatory clinical patient conditions due to their high biocompatibility, ability to physically interact with biomolecules, large surface area, and low toxicity. In this review, the most common bioabsorbable materials such as those belonging to natural polymers and proteins for the manufacture of NMs and NPs are reviewed. In addition to biocompatibility and bioresorption, current methodology on surface functionalization is also revisited and the most recent applications are highlighted. Considering the most recent use in the field of biosensors, tethered lipid bilayers, drug delivery, wound dressing, skin regeneration, targeted chemotherapy and imaging/diagnostics, functionalized NMs and NPs have become one of the main pillars of modern biomedical applications

Flexible electrode based on nitrogen carbon quantum dots for dopamine detection

The simple fabrication of a flexible electrochemical sensor from nitrogen carbon quantum dots (NCQDs) on a modified ITO surface for dopamine detection is presented. NCQD dispersion was used to modify an ITO-coated PET flexible substrate, which was previously pretreated with oxygen plasma to activate its surface. Optical, chemical, electrochemical and electrocatalytic characterizations were performed on the proposed electrode with UV–vis, FT-IR, TEM, CV, and EIS. The detection limit of the NCQDs-ITO/PET sensor determined via CV was 4.7 µM over a very wide range of 0.0–2.0 mM in a linear regimen. This sensor demonstrated outstanding as a flexible platform and a facile fabrication for the detection of DA without the need to work with composites or complex systems that involve different nanoparticles.Peer ReviewedPostprint (author's final draft

Exploring the Effects and Interactions of Conducting Polymers in the Volume Phase Transition of Thermosensitive Conducting Hydrogels

Conducting polymers (CPs) play a vital role in imparting electrochemical and photothermal properties to thermosensitive conducting hydrogels (TCH). The application of TCH is expanding not only for biomedical applications but also to address water scarcity. While the volume phase transition (VPT) phenomenon in thermosensitive polymers has been extensively studied, the contribution of CPs to this process and the underlying chemical interactions remain unclear and low explored. In this study, we present a novel conducting polymer hydrogel (CPH) utilizing the thermosensitive polymer poly(N-isopropylacrylamide) (PNIPAAm) enriched with poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles as a model system. This serves as a platform for both experimental and theoretical investigations into the influence of CPs on VPT. Through a comprehensive examination of hydrogel responses to temperature employing Raman spectroscopy, atomistic simulations using advanced hybrid methodologies, and artificial intelligence, we unveil a shielding effect of CP. This effect arises from robust chemical interactions with NIPAAm, inducing a selective dehydration of the hydrogel microenvironment. Remarkably, this mirrors the phenomenon observed during VPT triggered by an increase in the hydrogel temperature. Understanding the intricate interactions between conducting and thermosensitive polymers is imperative for the systematic development and fine-tuning of the performance of future CPHs. This knowledge ensures a more precise adaptation of these materials to their intended end applications