Publications by authors named "Dirk Mayer"

Purpose Of Review: This review examines the existing literature on metabolic pathways associated with bladder cancer (BC) and investigates four domains: (1) diagnoses, (2) cancer classification (staging & grading), (3) tracking, and (4) treatment.

Recent Findings: A systematic search of relevant databases identified studies meeting predefined inclusion criteria. A diverse array of metabolic pathways was found to hold significant biological and clinical relevance to BC, with particular emphasis on amino acid (AA), lipid, nucleic acid (NA), and bioenergetic pathways.

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With the goal of fast and accurate diagnosis of infectious diseases, this study presents a novel electrochemical biosensor that employs a refined aptamer (C9t) for the detection of spike (S) protein SARS-CoV-2 variants in a flexible multielectrode aptasensor array with PoC capabilities. Two aptamer modifications were employed: removing the primer binding sites and including two dithiol phosphoramidite anchor molecules. Thus, reducing fabrication time from 24 to 3 h and increasing the stability and sparseness for multi-thiol aptasensors compared to a standard aptasensor using single thiols, without a reduction in aptamer density.

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Biosensors based on DNA aptamer receptors are increasingly used in diagnostic applications. To improve the sensitivity and specificity of aptasensors, parameters affecting the stability and binding efficiency of the receptor layer need to be identified and studied. For example, the blocking step, i.

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The rapid and reliable detection and quantification of nucleic acids is crucial for various applications, including infectious disease and cancer diagnostics. While conventional methods, such as the quantitative polymerase chain reaction are widely used, they are limited to the laboratory environment due to their complexity and the requirement for sophisticated equipment. In this study, we present a novel amplification-free digital sensing strategy by combining the collateral cleavage activity of the Cas12a enzyme with single-impact electrochemistry.

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In this work, we combined plasmon-enhanced fluorescence and electrochemical (PEF-EC) transduction mechanisms to realize a highly sensitive dual-transducer aptasensor. To implement two traducers in one biosensor, a novel large-scale nanoimprint lithography process was introduced to fabricate gold nanopit arrays (AuNpA) with unique fringe structures. Light transmitting through the AuNpA samples exhibited a surface plasmon polariton peak overlapping with the excitation peak of the C7 aptamer-associated fluorophore methylene blue (MB).

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Background: Diabetes patients suffer either from insulin deficiency or resistance with a high risk of severe long-term complications, thus the quantitative assessment of insulin level is highly desired for diabetes surveillance and management. Utilizing insulin-capturing aptamers may facilitate the development of affordable biosensors however, their rigid G-quadruplex structures impair conformational changes of the aptamers and diminish the sensor signals.

Results: Here we report on a ratiometric, electrochemical insulin aptasensor which is achieved by hybridization of an insulin-capturing aptamer and a partially complementary ssDNA to break the rigid G-quadruplex structures.

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Article Synopsis
  • - MRI with hyperpolarized (HP) C agents allows for the measurement of altered metabolism in various diseases, including cancers and organ diseases, and has seen increased application in human studies over the last decade due to improved preparation methods of HP agents.
  • - This paper focuses on the use of [1-C]pyruvate, the most popular HP agent, and is organized into four main sections: agent preparation, MRI system setup, data collection, and analysis, highlighting essential components for effective studies.
  • - The findings come from the "HP C MRI Consensus Group" and aim to provide a comprehensive guide for best practices, addressing both successful studies and existing gaps, while fostering future advancements in metabolic imaging.
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Cable bacteria are filamentous, multicellular microorganisms that display an exceptional form of biological electron transport across centimeter-scale distances. Currents are guided through a network of nickel-containing protein fibers within the cell envelope. Still, the mechanism of long-range conduction remains unresolved.

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Background: MR spectroscopy (MRS) is a noninvasive tool for evaluating biochemical alterations, such as glutamate (Glu)/gamma-aminobutyric acid (GABA) imbalance and depletion of antioxidative glutathione (GSH) after traumatic brain injury (TBI). Thalamus, a critical and vulnerable region post-TBI, is challenging for MRS acquisitions, necessitating optimization to simultaneously measure GABA/Glu and GSH.

Purpose: To assess the feasibility and optimize acquisition and processing approaches for simultaneously measuring GABA, Glx (Glu + glutamine (Gln)), and GSH in the thalamus, employing Hadamard encoding and reconstruction of MEscher-GArwood (MEGA)-edited spectroscopy (HERMES).

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The goal of this study was to investigate the origin of brain lactate (Lac) signal in the healthy anesthetized rat after injection of hyperpolarized (HP) [1- C]pyruvate (Pyr). Dynamic two-dimensional spiral chemical shift imaging with flow-sensitizing gradients revealed reduction in both vascular and brain Pyr, while no significant dependence on the level of flow suppression was detected for Lac. These results support the hypothesis that the HP metabolites predominantly reside in different compartments in the brain (i.

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Article Synopsis
  • OECTs are advantageous for biochemical applications due to their ability to convert ions to electrons and their electrochemical gating, but the influence of capacitance on specific sensing events remains unclear.
  • Researchers designed integrated interdigitated OECTs (iOECTs) for malaria detection, discovering that transconductance decreased with thicker channels, particularly those with larger areas, indicating limited gating efficiency with smaller gold electrodes.
  • The thinner channel iOECTs displayed significantly higher sensitivity for malaria detection, achieving a detection limit of 3.2 aM, highlighting the importance of optimizing device geometry for improved biosensing performance.
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Article Synopsis
  • The study introduces an electrochemical aptasensor that uses small DNA aptamers and a PEG-functionalized interface for sensitive serotonin detection, crucial for understanding brain diseases.
  • The truncated aptamers enhance sensitivity by changing shape upon serotonin binding, which can be measured by changes in electrical current.
  • The sensor shows impressive performance with a detection range from 0.1 nM to 1000 nM and excellent selectivity and stability, making it promising for clinical diagnostics and neurochemical research.
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MRI with hyperpolarized (HP) C agents, also known as HP C MRI, can measure processes such as localized metabolism that is altered in numerous cancers, liver, heart, kidney diseases, and more. It has been translated into human studies during the past 10 years, with recent rapid growth in studies largely based on increasing availability of hyperpolarized agent preparation methods suitable for use in humans. This paper aims to capture the current successful practices for HP MRI human studies with [1-C]pyruvate - by far the most commonly used agent, which sits at a key metabolic junction in glycolysis.

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Article Synopsis
  • Electrochemical and optical platforms are widely used in biosensors, but relying on a single readout can lead to inaccuracies due to various factors.
  • A new dual-signal protocol combines electrochemical and extraordinary optical transmission (EOT) detection methods using gold nanopit arrays (AuNpA), which enhances sensitivity and detection range.
  • The study highlights the advantages of using dual-signal systems for biosensors and their potential applications in disease diagnosis and point-of-care testing.
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The combination of electrophysiology and neuroimaging methods allows the simultaneous measurement of electrical activity signals with calcium dynamics from single neurons to neuronal networks across distinct brain regions . While traditional electrophysiological techniques are limited by photo-induced artefacts and optical occlusion for neuroimaging, different types of transparent neural implants have been proposed to resolve these issues. However, reproducing proposed solutions is often challenging and it remains unclear which approach offers the best properties for long-term chronic multimodal recordings.

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Nowadays, many applications in diverse fields are taking advantage of micropillars such as optics, tribology, biology, and biomedical engineering. Among them, one of the most attractive is three-dimensional microelectrode arrays for in vivo and in vitro studies, such as cellular recording, biosensors, and drug delivery. Depending on the application, the micropillar's optimal mechanical response ranges from soft to stiff.

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In this work, a novel sandwich-type electrochemical immunosensor was developed for the quantitative detection of the carcinoembryonic antigen, an important tumor marker in clinical tests. The capture antibodies were immobilized on the surface of a gold disk electrode, while detection antibodies were attached to redox-tagged single-walled carbon nanohorns/thionine/AuNPs. Both types of antibody immobilization were carried out through Au-S bonds using the novel photochemical immobilization technique that ensures control over the orientation of the antibodies.

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Single-entity electrochemistry is a powerful technique to study the interactions of nanoparticles at the liquid-solid interface. In this work, we exploit Faradaic (background) processes in electrolytes of moderate ionic strength to evoke electrokinetic transport and study its influence on nanoparticle impacts. We implemented an electrode array comprising a macroscopic electrode that surrounds a set of 62 spatially distributed microelectrodes.

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This work demonstrates a lateral flow assay concept on the basis of stochastic-impact electrochemistry. To this end, we first elucidate requirements to employ silver nanoparticles as redox-active labels. Then, we present a prototype that utilizes nanoimpacts from biotinylated silver nanoparticles as readouts to detect free biotin in solution based on competitive binding.

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Despite significant eradication efforts, malaria remains a persistent infectious disease with high mortality due to the lack of efficient point-of-care (PoC) screening solutions required to manage low-density asymptomatic parasitemia. In response, we demonstrate a quantitative electrical biosensor based on system-integrated two-dimensional field-effect transistors (2DBioFETs) of reduced graphene oxide (rGO) as transducer for high sensitivity screening of the main malaria biomarker, Plasmodium falciparum lactate dehydrogenase (PfLDH). The 2DBioFETs were biofunctionalized with pyrene-modified 2008s aptamers as specific PfLDH receptors.

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The rapid spread of SARS-CoV-2 infection throughout the world led to a global public health and economic crisis triggering an urgent need for the development of low-cost vaccines, therapies and high-throughput detection assays. In this work, we used a combination of Ideal-Filter Capillary Electrophoresis SELEX (IFCE-SELEX), Next Generation Sequencing (NGS) and binding assays to isolate and validate single-stranded DNA aptamers that can specifically recognize the SARS-CoV-2 Spike glycoprotein. Two selected non-competing DNA aptamers, C7 and C9 were successfully used as sensitive and specific biological recognition elements for the development of electrochemical and fluorescent aptasensors for the SARS-CoV-2 Spike glycoprotein with detection limits of 0.

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Microfluidic paper-based analytical devices (μPADs) have experienced an unprecedented story of success. In particular, as of today, most people have likely come into contact with one of their two most famous examples─the pregnancy or the SARS-CoV-2 antigen test. However, their sensing performance is constrained by the optical readout of nanoparticle agglomeration, which typically allows only qualitative measurements.

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Recent advances in technology are expected to increase our current understanding of neuroscience. Nanotechnology and nanomaterials can alter and control neural functionality in both and experimental setups. The intersection between neuroscience and nanoscience may generate long-term neural interfaces adapted at the molecular level.

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A novel double-resonant plasmonic substrate for fluorescence amplification in a chip-based apta-immunoassay is herein reported. The amplification mechanism relies on plasmon-enhanced fluorescence (PEF) effect. The substrate consists of an assembly of plasmon-coupled and plasmon-uncoupled gold nanoparticles (AuNPs) immobilized onto a glass slide.

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Protic ionic liquids are promising electrolytes for fuel cell applications. They would allow for an increase in operation temperatures to more than 100 °C, facilitating water and heat management and, thus, increasing overall efficiency. As ionic liquids consist of bulky charged molecules, the structure of the electric double layer significantly differs from that of aqueous electrolytes.

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