49 research outputs found

    Application of disposable chiral plasmonics for biosensing and Raman spectroscopy

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    This thesis explores the capabilities of disposable chiral plasmonic metafilm assays, termed Disposable Plasmonic Assays, as a promising platform for biosensing and surface-enhanced Raman spectroscopy. The sensing and Raman properties of these metafilms arise from the excitation of surface plasmons when exposed to incident light. These plasmonic properties strongly depend on the geometric characteristics of the constituent nanostructures found in the metafilms. Specifically, the primary nanostructure employed throughout this research is the chiral 'shuriken' star, which generates chiral electromagnetic fields exhibiting greater chiral asymmetry than circularly polarized light. Monitoring changes in the resonance positions of the characteristic optical rotatory dispersion spectra produced by the Disposable Plasmonic Assays allows for the observation of surface binding events. By measuring resonance shift data and through the utilisation of various gold film functionalisation techniques, these assays are demonstrated as versatile, label-free biosensing platforms capable of specifically detecting a wide range of target proteins and virus particles from complex solutions. Furthermore, the multiplexing performance of these assays is showcased, enabling the detection of multiple different antigens and virions in a single experiment. These results highlight the potential of plasmonic metafilms as rapid and disposable point-of-care immunoassays for diagnostic applications. In addition to biosensing, the chiral geometry of Disposable Plasmonic Assays is exploited for the chiral discrimination of metal nanoparticles and small molecules using Surface Enhanced Raman Spectroscopy (SERS). By linking helicoid shaped gold nanoparticles to the metafilm surface via a dithiol linker, the chiral properties of both nanoparticles and metafilms combine, resulting in the creation of differential electromagnetic 'hotspot' regions based on their symmetry combinations. The electromagnetic intensity in these regions corresponds to the SERS signal obtained from the achiral dithiol linker molecule, facilitating a deeper understanding of the chirally dependent SERS phenomenon. These findings serve to validate and explain the differential SERS data obtained enantiomers of biomolecules and drug molecules from silver modified Disposable Plasmonic Assays

    Cellulose-Based Biosensing Platforms

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    Cellulose empowers measurement science and technology with a simple, low-cost, and highly transformative analytical platform. This book helps the reader to understand and build an overview of the state of the art in cellulose-based (bio)sensing, particularly in terms of the design, fabrication, and advantageous analytical performance. In addition, wearable, clinical, and environmental applications of cellulose-based (bio)sensors are reported, where novel (nano)materials, architectures, signal enhancement strategies, as well as real-time connectivity and portability play a critical role

    Selected Papers from the 1st International Electronic Conference on Biosensors (IECB 2020)

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    The scope of this Special Issue is to collect some of the contributions to the First International Electronic Conference on Biosensors, which was held to bring together well-known experts currently working in biosensor technologies from around the globe, and to provide an online forum for presenting and discussing new results. The world of biosensors is definitively a versatile and universally applicable one, as demonstrated by the wide range of topics which were addressed at the Conference, such as: bioengineered and biomimetic receptors; microfluidics for biosensing; biosensors for emergency situations; nanotechnologies and nanomaterials for biosensors; intra- and extracellular biosensing; and advanced applications in clinical, environmental, food safety, and cultural heritage fields

    Preparation, Physico-Chemical Properties and Biomedical Applications of Nanoparticles

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    Nowadays, the impact of nanotechnology on applications in medicine and biomedical sciences has broader societal and economic effects, enhancing awareness of the business, regulatory, and administrative aspects of medical applications. The selected papers included in the present Special Issue gives readers a critical, balanced and realistic evaluation of existing nanomedicine developments and future prospects, allowing practitioners to plan and make decisions.The topics of this book covers the use of nanoparticles and nanotechnology in medical applications including biomaterials for tissue regeneration, diagnosis and monitoring, surgery, prosthetics, drug delivery systems, nanocarriers, and wound dressing. I would like to express my gratitude to all contributors to this issue, who have given so much of their time and effort to help create this collection of high quality papers

    Grafeno em papel para dispositivos flexíveis: sensores e OLEDs

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    The interest in flexible electronics has been growing considerably due to the possibility of products and devices with novel functionalities and improved comfort in their utilization. Graphene, with a combination of properties, is a natural candidate for these applications. Simultaneously, paper electronics is proving itself as a potentially significant branch of flexible electronics. Thus, it is particularly interesting to investigate the combination of these two materials for the development of novel and disruptive applications. This work covers the development of two types of flexible devices based on gra-phene and paper: physical and electrochemical sensors and organic light emit-ting diodes (OLEDs). In the context of sensors, one of the most recent additions to the family of graphene-based materials is explored: laser-induced graphene obtained from paper (paper-LIG), a graphene foam synthesized by a fast and low-cost process. The sensibility of paper-LIG to mechanical stimuli (strain and bending), as well as to humidity and temperature (in the latter case also shown for laser-induced graphene obtained from xylan, a biopolymer similar to cellulose) is demonstrated. The development of these devices is accompanied by a study of the influence of the synthesis parameters on the obtained material, comprising a sizeable contribution to the description of this material and its applications in the literature. Additionally, a non-enzymatic paper-LIG transductor for the electrochemical detection and quantification of uric acid is presented, demonstrating its response capability in real human urine samples, with a sensitivity of 0.363 μA cm⁻² μM⁻¹ and a linear range that covers the clinically relevant concentration range for this physiological parameter. In the scope of OLEDs, an optimized graphene synthesis process by chemical vapour deposition is presented, with the goal of using this single-layer graphene as a transparent electrode. The issue of high surface roughness typical of paper is addressed by the use of cellulose nanocrystal membranes and transparent rolling papers as flexible, biodegradable substrates, accompanied by the development of modified graphene film transfer and stacking approaches. The properties of this material are improved by thermal evaporation of MoO3, allowing the construction of OLEDs with 0.34% external quantum efficiency. The development of these devices not only contributes to reaffirm the vast potential of graphene, but also serves to introduce novel approaches in the context of low-cost and biodegradable flexible devices.O interesse na eletrónica flexível tem crescido consideravelmente devido ao de-senvolvimento de produtos e dispositivos com novas funcionalidades e maior conforto na utilização dos mesmos. O grafeno, com uma combinação única de propriedades, surge como um candidato natural para este tipo de aplicações. Simultaneamente, a eletrónica em papel tem-se revelado como uma vertente potencialmente significativa na área da eletrónica flexível. Assim, torna-se parti-cularmente interessante investigar a combinação destes dois materiais para o desenvolvimento de novas e disruptivas aplicações. Este trabalho explora o desenvolvimento de dois tipos de dispositivos flexíveis à base de grafeno em papel: sensores físicos e eletroquímicos e díodos orgânicos emissores de luz (OLEDs). No contexto dos sensores é abordada uma das mais recentes adições à família dos materiais à base de grafeno: o grafeno induzido por laser obtido a partir do papel (paper-LIG), uma espuma de grafeno sintetizada por um processo rápido e de baixo custo. É demonstrada pela primeira vez a sensibilidade do paper-LIG a estímulos mecânicos (distensão e flexão), bem como à humidade e tempera-tura (neste último caso também para o grafeno induzido por laser obtido a partir de xilana, um biopolímero semelhante à celulose). O desenvolvimento destes dispositivos é acompanhado por um estudo da influência dos parâmetros de sín-tese no material obtido, constituindo uma contribuição significativa para a des-crição deste material e das suas aplicações na literatura. É ainda apresentado um transdutor não-enzimático de paper-LIG, para a deteção e quantificação ele-troquímica de ácido úrico, demonstrando a sua capacidade de resposta em amostras reais de urina humana, com uma sensibilidade de 0.363 μA μA cm⁻² μM⁻¹ e uma gama linear que abrange o intervalo de concentrações clinicamente rele-vante para este parâmetro fisiológico. No âmbito dos OLEDs, é apresentado um processo otimizado de síntese de grafeno monocamada por deposição química em fase vapor, com vista à sua utilização como elétrodo transparente. A questão da elevada rugosidade tipica-mente associada ao papel é colmatada pelo uso de membranas de celulose nanocristalina e de mortalhas transparentes como substratos flexíveis e biode-gradáveis, acompanhado pelo desenvolvimento de técnicas modificadas de transferência e empilhamento de múltiplas camadas de grafeno. As proprieda-des deste material são melhoradas pela evaporação térmica de MoO3, permi-tindo a construção de OLEDs com 0.34% de eficiência quântica externa. O desenvolvimento destes dispositivos não só contribui para reafirmar o vasto potencial do grafeno em conjugação com o papel, como serve também para introduzir novas abordagens no contexto de dispositivos flexíveis de baixo custo e biodegradáveis.Programa Doutoral em Nanociências e Nanotecnologi

    Electrochemical sensors and biosensors: new horizons and challenges in their integration in multisensor systems for food industry applications

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    La presente Tesis doctoral, plantea el desarrollo de sensores y biosensores para el análisis de alimentos, empleando diferentes materiales y nanomateriales sensibles. Se trata de sensores y biosensores electroquímicos que permiten detectar compuestos de interés en alimentos líquidos tales como leches o vinos. Los sensores se han diseñado empleado diferentes materiales sensibles y tecnologías relacionadas con la Nanociencia, con el propósito de mejorar parámetros analíticos como son: selectividad, sensibilidad, reproducibilidad y repetitividad. Los sensores y biosensores se han utilizado para desarrollar redes de sensores que forman lenguas electrónicas y bioelectrónicas. La preparación y caracterización de los sensores y biosensores desarrollados, así como sus respuestas electroquímicas y su funcionamiento como parte de lenguas electrónicas, se discuten mediante los artículos científicos, indexados en revistas internacionales, incluidos en esta Tesis Doctoral.Departamento de Química Física y Química InorgánicaDoctorado en Físic

    Carbon-Based Nanomaterials for (Bio)Sensors Development

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    Carbon-based nanomaterials have been increasingly used in sensors and biosensors design due to their advantageous intrinsic properties, which include, but are not limited to, high electrical and thermal conductivity, chemical stability, optical properties, large specific surface, biocompatibility, and easy functionalization. The most commonly applied carbonaceous nanomaterials are carbon nanotubes (single- or multi-walled nanotubes) and graphene, but promising data have been also reported for (bio)sensors based on carbon quantum dots and nanocomposites, among others. The incorporation of carbon-based nanomaterials, independent of the detection scheme and developed platform type (optical, chemical, and biological, etc.), has a major beneficial effect on the (bio)sensor sensitivity, specificity, and overall performance. As a consequence, carbon-based nanomaterials have been promoting a revolution in the field of (bio)sensors with the development of increasingly sensitive devices. This Special Issue presents original research data and review articles that focus on (experimental or theoretical) advances, challenges, and outlooks concerning the preparation, characterization, and application of carbon-based nanomaterials for (bio)sensor development

    Applications of Molecularly Imprinted Films

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    Molecularly imprinted polymers are materials that have voids that are complementary in shape, size, and electronic environment to a specific molecule used for preparation, known as the template. These voids are specific recognition sites that bind the templates preferentially and are used specifically for biomimetic sensors and for solid-phase extraction. Because the specific surface is very important during this process, the use of films and membranes is preferred. This book contains four articles dedicated to sensor application (three research articles and one review) and one research article dedicated to solid-phase extraction

    Two-dimensional graphitic carbon nitride (g-C3N4) nanosheets and their derivatives for diagnosis and detection applications

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    The early diagnosis of certain fatal diseases is vital for preventing severe consequences and contributes to a more effective treatment. Despite numerous conventional methods to realize this goal, employing nanobiosensors is a novel approach that provides a fast and precise detection. Recently, nanomaterials have been widely applied as biosensors with distinctive features. Graphite phase carbon nitride (g-C3N4) is a two-dimensional (2D) carbon-based nanostructure that has received attention in biosensing. Biocompatibility, biodegradability, semiconductivity, high photoluminescence yield, low-cost synthesis, easy production process, antimicrobial activity, and high stability are prominent properties that have rendered g-C3N4 a promising candidate to be used in electrochemical, optical, and other kinds of biosensors. This review presents the g-C3N4 unique features, synthesis methods, and g-C3N4-based nanomaterials. In addition, recent relevant studies on using g-C3N4 in biosensors in regard to improving treatment pathways are reviewed

    Rapid methods for antimicrobial resistance diagnosis in contaminated soils for effective remediation strategy

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    Antimicrobial resistance (AMR) in the environment is a global concern for public health and recent studies have shown that various soil pollutants (e.g. heavy metals, petroleum hydrocarbons) can cause the emergence of antibiotic-resistant bacteria and antibiotic-resistance genes in the soil. This emergence of AMR in soil is therefore prompting the research community for the development of rapid and real-time monitoring tools to better understand the source, fate and transfer pathway of AMR in contaminated soils. In this respect, the recent development of rapid sensors-based methods has been critically reviewed. The analytical performance of each sensing technique along with their advantages and limitations is further discussed to inform future development needs for the next generation sensors that would allow rapid and multiplexed detection of AMR in contaminated soils. By doing so, it would assist the decision making during remediation project and provide crucial insights into the risk assessment for contaminated sites
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