19 research outputs found

    Sensory polymeric foams as a tool for improving sensing performance of sensory polymers

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    Microcellular sensory polymers prepared from solid sensory polymeric films were tested in an aqueous Hg(II) detection process to analyze their sensory behavior. First, solid acrylic-based polymeric films of 100 ”m thickness were obtained via radical copolymerization process. Secondly, dithizone sensoring motifs were anchored in a simple five-step route, obtaining handleable colorimetric sensory films. To create the microporous structure, films were foamed in a ScCO2 batch process, carried out at 350 bar and 60 °C, resulting in homogeneous morphologies with cell sizes around 5 ”m. The comparative behavior of the solid and foamed sensory films was tested in the detection of mercury in pure water media at 2.2 pH, resulting in a reduction of the response time (RT) around 25% and limits of detection and quantification (LOD and LOQ) four times lower when using foamed films, due to the increase of the specific surface associated to the microcellular structure.Fondo Europeo de Desarrollo Regional) and both the Spanish Agencia Estatal de Investigación (MAT2017-84501-R) and the Consejeria de Educación-Junta de Castilla y León (BU306P18

    Low Dimensional Nanostructures: Measurement and Remediation Technologies Applied to Trace Heavy Metals in Water

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    A nanostructure is a system in which at least one external dimension is in the nanoscale, it means a length range smaller than 100 nm. Nanostructures can be natural or synthetic and determine the physicochemical properties of bulk materials. Due to their high surface area and surface reactivity, they can be an efficient alternative to remove contaminants from the environment, including heavy metals from water. Heavy metals like mercury (Hg), cadmium (Cd), arsenic (As), lead (Pb), and chromium (Cr) are highly poisonous and hazardous to human health due to their non-biodegradability and highly toxic properties, even at trace levels. Thus, efficient, low-cost, and environmentally friendly methodologies of removal are needed. These needs for removal require fast detection, quantification, and remediation to have heavy metal-free water. Nanostructures emerged as a powerful tool capable to detect, quantify, and remove these contaminants. This book chapter summarizes some examples of nanostructures that have been used on the detection, quantification, and remediation of heavy metals in water

    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

    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

    Biosensors for Diagnosis and Monitoring

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    Biosensor technologies have received a great amount of interest in recent decades, and this has especially been the case in recent years due to the health alert caused by the COVID-19 pandemic. The sensor platform market has grown in recent decades, and the COVID-19 outbreak has led to an increase in the demand for home diagnostics and point-of-care systems. With the evolution of biosensor technology towards portable platforms with a lower cost on-site analysis and a rapid selective and sensitive response, a larger market has opened up for this technology. The evolution of biosensor systems has the opportunity to change classic analysis towards real-time and in situ detection systems, with platforms such as point-of-care and wearables as well as implantable sensors to decentralize chemical and biological analysis, thus reducing industrial and medical costs. This book is dedicated to all the research related to biosensor technologies. Reviews, perspective articles, and research articles in different biosensing areas such as wearable sensors, point-of-care platforms, and pathogen detection for biomedical applications as well as environmental monitoring will introduce the reader to these relevant topics. This book is aimed at scientists and professionals working in the field of biosensors and also provides essential knowledge for students who want to enter the field

    Bio-Functionalized Graphene Field-Effect Transistors For The Detection Of Nucleic Acids And Drug Targets

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    The need for scalable, rapid, sensitive, label-free detection of small biomolecules and chemicals such as proteins, nucleic acids or market drugs is central to the field of biomolecular and chemical sensing. Detection of these biomolecules and chemicals is relevant for early disease diagnostics and therapeutic drug monitoring to prolong lifespans, treat patients in a brief timeframe, and decrease medical costs. Various ailments, such as cancers, are the source of up-regulation or down-regulation of certain biomolecules, or “biomarkers” in human fluids, and are indicative of the presence of the disease when compared to human fluids from a healthy subject. By detecting these biomarkers in low concentrations, or by tracking their change in concentration in human samples, scientists could create an effective early disease diagnostics tool that would be used at the point-of-care. In parallel, detection of market drugs in human samples could replace the need for more expensive and time-consuming analytical techniques such as liquid chromatography-mass spectrometry (LC-MS). The work presented here explores the necessary proof-of-concept for the creation of point-of-care devices for medical diagnostics and therapeutic drug monitoring. It details the process of synthetic nucleic acid detection down to attomolar concentrations, the detection of single base-pair mismatches in nucleic acid strands, and drug target detection in concentrations (1-10 ng/mL) far less than those found in human fluid, the latter for the purpose of therapeutic drug monitoring or “drug compliance” testing. Such sensitivity could only be achieved with the nanomaterial graphene, a two-dimensional allotrope of carbon with the highest electron mobility at room temperature of any material currently known, and with exceptional robustness and biocompatibility. The work here is based on the use of graphene field-effect transistors, or GFETs, for nucleic acid and drug target sensing, and further explores the various uses of graphene for protein and pH sensing, as well as binding of protein-nanoparticle assemblies and neuropeptide-receptor binding, through either rigid or flexible substrates

    Fundamentals of SARS-CoV-2 Biosensors

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    COVID-19 diagnostic strategies based on advanced techniques are currently essential topics of interest, with crucial roles in scientific research. This book integrates fundamental concepts and critical analyses that explore the progress of modern methods for the detection of SARS-CoV-2

    Integration of Biomolecular Recognition Elements with Solid-State Devices

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    Continued advances in stand-alone chemical sensors requires the introduction of new materials and transducers, and the seamless integration of the two. Electronic sensors represent one of the most efficient and versatile sensing transducers that offer advantages of high sensitivity, compatibility with multiple types of materials, network connectivity, and capability of miniaturization. With respect to materials to be used on this platform, many classes and subclasses of materials, including polymers, oxides, semiconductors, and composites have been investigated for various sensing environments. Despite numerous commercial products, major challenges remain. These include enhancing materials for selectivity/specificity, and low cost integration/ miniaturization of devices. Breakthroughs in either area would signify a transformative innovation. In this thesis, a combined materials and devices approach has been explored to address the above challenges. Biomolecular recognition elements, exemplified by aptamers, are the most recent addition to the library of tunable materials for specific detection of analytes. At the same time, nanoscale electrical devices based on tunnel junctions offer the potential for simple design, large scale integration, field deployment, network connectivity, and importantly, miniaturization to the molecular scale. To first establish a framework for studying sorption properties of solid oligonucleotides, custom designed aptamers sequences were studied to determine equilibrium partition coefficients. Linear-solvation-energy-relationship (LSER) analysis provides quantifications of non-covalent bonding properties and reveals the dominance of hydrogen bonding basicity in oligonucleotides. We find that DNA-analyte interactions have selective sorption properties similar to synthetic polymers. LSER analysis provides a chemical basis for material-analyte interactions. Oligonucleotide sequences were integrated with gold nanoparticle chemiresistors to transfer the selective sorption properties to microfabricated electrical devices. Responses generated by oligonucleotides under dry conditions were similar to standard organic mediums used as capping agents and suggests that DNA-based chemiresistor sensors operate with a similar mechanism based on sorption induced swelling. The equilibrium mass-sorption behavior of bulk DNA films could be translated to the chemiresistor sensitivity profiles. Our work establishes oligonucleotides, including aptamers, as a class of sorptive materials that can be systematically studied, engineered, and integrated with nanoscale electronic sensor devices. Experiments to investigate secondary structure effects were inconclusive and we conclude that further work should investigate DNA aptamers in buffered, aqueous environments to unequivocally establish the ability of chemiresitors to signal molecular recognition. Concurrent with the above studies, device integration and miniaturization was investigated to combine many sensing materials into a single, compact design. Arrays of nanoscale chemiresistors with critical features on the order of 10 – 100 nm were developed, using dielectrophoretic assembly of gold nanoparticles to control placement of the sensing material with nanometer accuracy. The nanoscale chemiresistors achieved the smallest known gold nanoparticle chemiresistors relying on just 2 – 3 layers of nanoparticles within 50 nm gaps, and were found to be more robust and less dependent on film thickness than previously published designs. Due to shorter diffusion paths, the sensors are also faster in response and recovery. A proof-of-concept, integrated single-chip sensor array was created and it showed similar response patterns as non-integrated sensor arrays. Dielectrophoresis is established as a key enabler for nanoscale, integrated devices. Based on the major findings of the thesis work, additional investigations were initiated to investigate the potential for nanoscale chemiresitor sensors to operate in buffered, aqueous (liquid) flow cells. Preliminary experiments show that chemiresistor sensing is transferable to liquid environments where analyte molecules are observed to partition from the bulk liquid to the sensing materials, leading to a detectable change of the device electrical properties. Comparing micron- and nano-scale devices fabricated using aqueous oligonucleotide-functionalized gold nanoparticles, it was found that nanoscale chemiresistors are more resistant to solvent damage than 5 ”m chemiresistors. We conclude that future experiments to investigate aptamer sensing in aqueous solutions is a promising direction. Overall, this thesis is a significant contribution to materials development and device design to attain improved sensor selectivity and higher levels of device integration. First, it offers a scheme for design, selection, and validation of materials that confer analyte-specific interactions. Second, it paves the way for large scale sensor integration and parallel operation on a single chip. Lastly, it offers an approach to combine biomolecular recognition elements with electronic devices into robust, nanoscale detection systems. Based on the major findings of the thesis work, additional investigations were initiated to investigate the potential for nanoscale chemiresitor sensors to operate in buffered, aqueous (liquid) flow cells. Preliminary experiments show that chemiresistor sensing is transferable to liquid environments where analyte molecules are observed to partition from the bulk liquid to the sensing materials, leading to a detectable change of the device electrical properties. Comparing micron- and nano-scale devices fabricated using aqueous oligonucleotide-functionalized gold nanoparticles, it was found that nanoscale chemiresistors are more resistant to solvent damage than 5 ”m chemiresistors. We conclude that future experiments to investigate aptamer sensing in aqueous solutions is a promising direction. Overall, this thesis is a significant contribution to materials development and device design to attain improved sensor selectivity and higher levels of device integration. First, it offers a scheme for design, selection, and validation of materials that confer analyte-specific interactions. Second, it paves the way for large scale sensor integration and parallel operation on a single chip. Lastly, it offers an approach to combine biomolecular recognition elements with electronic devices into robust, nanoscale detection systems
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