Publications by authors named "Pedro Estrela"

63 Publications

Pre-concentration of microRNAs by LNA-modified magnetic beads for enhancement of electrochemical detection.

Sci Rep 2021 10 4;11(1):19650. Epub 2021 Oct 4.

Department of Electronic and Electrical Engineering, University of Bath, Bath, BA2 7AY, UK.

MicroRNAs are extremely promising candidates for early cancer diagnosis and prognosis. The levels of circulating microRNAs provide valuable information about cancer disease at its early stages. However, the levels of microRNAs that need to be detected are extremely low and difficult to discriminate from a large pool of oligonucleotides. There is the need for accurate, rapid and sensitive detection methodologies for detection of microRNAs. We developed electrochemical impedance spectroscopy peptide nucleic acid (PNA)-based sensors that can detect miRNAs in diluted serum with a limit of detection of 0.38 fM. In order to further improve the accuracy and reliability of the sensors, we developed an assay using magnetic beads for simple and rapid fishing of target microRNAs from solution and its pre-concentration prior to electrochemical detection. Our methodology utilizes magnetic beads for the capture of the target microRNA from solution and brings the concentrated sample to the sensor surface. We modify the magnetic beads with locked nucleic acids (LNA), which have high affinity and specificity to their complementary microRNA sequence. The separated and concentrated microRNA is then detected using the PNA-based sensors. By exposing the sensing electrodes only to the captured microRNAs, interferences from other nucleotides or biomolecules from the sample are eliminated.
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http://dx.doi.org/10.1038/s41598-021-99145-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8490432PMC
October 2021

Multiplexed Prostate Cancer Companion Diagnostic Devices.

Sensors (Basel) 2021 Jul 24;21(15). Epub 2021 Jul 24.

Centre for Biosensors, Bioelectronics and Biodevices (C3Bio), Department of Electronic & Electrical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK.

Prostate cancer (PCa) remains one of the most prominent forms of cancer for men. Since the early 1990s, Prostate-Specific Antigen (PSA) has been a commonly recognized PCa-associated protein biomarker. However, PSA testing has been shown to lack in specificity and sensitivity when needed to diagnose, monitor and/or treat PCa patients successfully. One enhancement could include the simultaneous detection of multiple PCa-associated protein biomarkers alongside PSA, also known as multiplexing. If conventional methods such as the enzyme-linked immunosorbent assay (ELISA) are used, multiplexed detection of such protein biomarkers can result in an increase in the required sample volume, in the complexity of the analytical procedures, and in adding to the cost. Using companion diagnostic devices such as biosensors, which can be portable and cost-effective with multiplexing capacities, may address these limitations. This review explores recent research for multiplexed PCa protein biomarker detection using optical and electrochemical biosensor platforms. Some of the novel and potential serum-based PCa protein biomarkers will be discussed in this review. In addition, this review discusses the importance of converting research protocols into multiplex point-of-care testing (xPOCT) devices to be used in near-patient settings, providing a more personalized approach to PCa patients' diagnostic, surveillance and treatment management.
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http://dx.doi.org/10.3390/s21155023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8347987PMC
July 2021

Utilising Commercially Fabricated Printed Circuit Boards as an Electrochemical Biosensing Platform.

Micromachines (Basel) 2021 Jul 3;12(7). Epub 2021 Jul 3.

Centre for Biosensors, Bioelectronics and Biodevices (C3Bio), Department of Electronic & Electrical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK.

Printed circuit boards (PCBs) offer a promising platform for the development of electronics-assisted biomedical diagnostic sensors and microsystems. The long-standing industrial basis offers distinctive advantages for cost-effective, reproducible, and easily integrated sample-in-answer-out diagnostic microsystems. Nonetheless, the commercial techniques used in the fabrication of PCBs produce various contaminants potentially degrading severely their stability and repeatability in electrochemical sensing applications. Herein, we analyse for the first time such critical technological considerations, allowing the exploitation of commercial PCB platforms as reliable electrochemical sensing platforms. The presented electrochemical and physical characterisation data reveal clear evidence of both organic and inorganic sensing electrode surface contaminants, which can be removed using various pre-cleaning techniques. We demonstrate that, following such pre-treatment rules, PCB-based electrodes can be reliably fabricated for sensitive electrochemical biosensors. Herein, we demonstrate the applicability of the methodology both for labelled protein (procalcitonin) and label-free nucleic acid (-specific DNA) biomarker quantification, with observed limits of detection (LoD) of 2 pM and 110 pM, respectively. The proposed optimisation of surface pre-treatment is critical in the development of robust and sensitive PCB-based electrochemical sensors for both clinical and environmental diagnostics and monitoring applications.
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http://dx.doi.org/10.3390/mi12070793DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8305449PMC
July 2021

Printable graphene BioFETs for DNA quantification in Lab-on-PCB microsystems.

Sci Rep 2021 05 10;11(1):9815. Epub 2021 May 10.

Centre for Biosensors, Bioelectronics and Biodevices (C3Bio) and Department of Electronic & Electrical Engineering, University of Bath, Bath, BA2 7AY, UK.

Lab-on-Chip is a technology that aims to transform the Point-of-Care (PoC) diagnostics field; nonetheless a commercial production compatible technology is yet to be established. Lab-on-Printed Circuit Board (Lab-on-PCB) is currently considered as a promising candidate technology for cost-aware but simultaneously high specification applications, requiring multi-component microsystem implementations, due to its inherent compatibility with electronics and the long-standing industrial manufacturing basis. In this work, we demonstrate the first electrolyte gated field-effect transistor (FET) DNA biosensor implemented on commercially fabricated PCB in a planar layout. Graphene ink was drop-casted to form the transistor channel and PNA probes were immobilized on the graphene channel, enabling label-free DNA detection. It is shown that the sensor can selectively detect the complementary DNA sequence, following a fully inkjet-printing compatible manufacturing process. The results demonstrate the potential for the effortless integration of FET sensors into Lab-on-PCB diagnostic platforms, paving the way for even higher sensitivity quantification than the current Lab-on-PCB state-of-the-art of passive electrode electrochemical sensing. The substitution of such biosensors with our presented FET structures, promises further reduction of the time-to-result in microsystems combining sequential DNA amplification and detection modules to few minutes, since much fewer amplification cycles are required even for low-abundance nucleic acid targets.
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http://dx.doi.org/10.1038/s41598-021-89367-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8111018PMC
May 2021

Electrochemical Biosensors for Cytokine Profiling: Recent Advancements and Possibilities in the Near Future.

Biosensors (Basel) 2021 Mar 23;11(3). Epub 2021 Mar 23.

School of Medical Science and Technology (SMST), Indian Institute of Technology Kharagpur, Kharagpur 721302, India.

Cytokines are soluble proteins secreted by immune cells that act as molecular messengers relaying instructions and mediating various functions performed by the cellular counterparts of the immune system, by means of a synchronized cascade of signaling pathways. Aberrant expression of cytokines can be indicative of anomalous behavior of the immunoregulatory system, as seen in various illnesses and conditions, such as cancer, autoimmunity, neurodegeneration and other physiological disorders. Cancer and autoimmune diseases are particularly adept at developing mechanisms to escape and modulate the immune system checkpoints, reflected by an altered cytokine profile. Cytokine profiling can provide valuable information for diagnosing such diseases and monitoring their progression, as well as assessing the efficacy of immunotherapeutic regiments. Toward this goal, there has been immense interest in the development of ultrasensitive quantitative detection techniques for cytokines, which involves technologies from various scientific disciplines, such as immunology, electrochemistry, photometry, nanotechnology and electronics. This review focusses on one aspect of this collective effort: electrochemical biosensors. Among the various types of biosensors available, electrochemical biosensors are one of the most reliable, user-friendly, easy to manufacture, cost-effective and versatile technologies that can yield results within a short period of time, making it extremely promising for routine clinical testing.
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http://dx.doi.org/10.3390/bios11030094DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8004910PMC
March 2021

Impedimetric aptamer-based glycan PSA score for discrimination of prostate cancer from other prostate diseases.

Biosens Bioelectron 2021 Mar 29;175:112872. Epub 2020 Nov 29.

Centre for Biosensors, Bioelectronics and Biodevices (C3Bio), University of Bath, BA2 7AY, Bath, United Kingdom; Department of Electronic and Electrical Engineering, University of Bath, BA2 7AY, Bath, United Kingdom. Electronic address:

Prostate specific antigen (PSA) is the common biomarker for prostate cancer (PCa). However, its lack of specificity to differentiate PCa from benign prostate disorders stimulates the search for alternative cancer biomarkers to improve the clinical management of the patients. Different studies have described changes in the core-fucosylation level of PSA between PCa patients and healthy controls. To exploit these findings, we have adapted an impedimetric aptamer-based sensor to the dual recognition of PSA. Two different aptamers, PSAG-1 and anti-PSA, are immobilized onto two adjacent nanostructured gold electrodes. The direct binding from diluted serum samples of specific glycosylated-PSA to the first sensor and total PSA to the second one leads to changes in the charge transfer resistance, which correlate to the amount of glycosylated and total PSA in the sample. The sensors are able to measure PSA in serum with a dynamic range between 0.26 and 62.5 ng/mL (PSAG-1) and from 0.64 to 62.5 ng/mL (anti-PSA), with a reproducibility of 5.4 %. The final output of the proposed platform is the ratio between PSAG-1 reactive PSA and total PSA, defined as the glycan score. The glycan score was tested in serum samples from patients with different pathologies, showing excellent correlation between the measured score and the known diagnosis of the patients. Hence this dual aptamer-based impedimetric biosensor could be used as a minimally invasive method for the diagnosis of prostate cancer.
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http://dx.doi.org/10.1016/j.bios.2020.112872DOI Listing
March 2021

Hydrogel-Forming Microneedles: Current Advancements and Future Trends.

Macromol Biosci 2021 02 26;21(2):e2000307. Epub 2020 Nov 26.

Materials for Health Lab, Department of Chemical Engineering, University of Bath, Bath, BA2 7AY, UK.

In this focused progress review, the recent developments and trends of hydrogel-forming microneedles (HFMs) and potential future directions are presented. Previously, microneedles (solid, hollow, coated, and dissolving microneedles) have primarily been used to enhance the effectiveness of transdermal drug delivery to facilitate a wide range of applications such as vaccinations and antibiotic delivery. However, the recent trend in microneedle development has resulted in microneedles formed from hydrogels which have the ability to offer transdermal drug delivery and, due to the hydrogel swelling nature, passively extract interstitial fluid from the skin, meaning they have the potential to be used for biocompatible minimally invasive monitoring devices. Thus, in this review, these recent trends are highlighted, which consolidate microneedle design considerations, hydrogel formulations, fabrication processes, applications of HFMs and the potential future opportunities for utilizing HFMs for personalized healthcare monitoring and treatment.
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http://dx.doi.org/10.1002/mabi.202000307DOI Listing
February 2021

Label-Free DNA Biosensor Using Modified Reduced Graphene Oxide Platform as a DNA Methylation Assay.

Materials (Basel) 2020 Nov 3;13(21). Epub 2020 Nov 3.

Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1665/1, 613 00 Brno, Czech Republic.

This work reports the use of modified reduced graphene oxide (rGO) as a platform for a label-free DNA-based electrochemical biosensor as a possible diagnostic tool for a DNA methylation assay. The biosensor sensitivity was enhanced by variously modified rGO. The rGO decorated with three nanoparticles (NPs)-gold (AuNPs), silver (AgNPs), and copper (CuNPs)-was implemented to increase the electrode surface area. Subsequently, the thiolated DNA probe (single-stranded DNA, ssDNA-1) was hybridized with the target DNA sequence (ssDNA-2). After the hybridization, the double-stranded DNA (dsDNA) was methylated by M.SssI methyltransferase (MTase) and then digested via a HpaII endonuclease specific site sequence of CpG (5'-CCGG-3') islands. For monitoring the MTase activity, differential pulse voltammetry (DPV) was used, whereas the best results were obtained by rGO-AuNPs. This assay is rapid, cost-effective, sensitive, selective, highly specific, and displays a low limit of detection (LOD) of 0.06 U·mL. Lastly, this study was enriched with the real serum sample, where a 0.19 U·mL LOD was achieved. Moreover, the developed biosensor offers excellent potential in future applications in clinical diagnostics, as this approach can be used in the design of other biosensors.
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http://dx.doi.org/10.3390/ma13214936DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7663213PMC
November 2020

Ultra stable, inkjet-printed pseudo reference electrodes for lab-on-chip integrated electrochemical biosensors.

Sci Rep 2020 10 13;10(1):17152. Epub 2020 Oct 13.

Centre for Biosensors, Bioelectronics and Biodevices (C3Bio) and Department of Electronic and Electrical Engineering, University of Bath, Bath, BA2 7AY, UK.

Lab-on-Chip technology comprises one of the most promising technologies enabling the widespread adoption of Point-of-Care testing in routine clinical practice. However, until now advances in Lab-on-Chip have not been translated to the anticipated degree to commercialized tools, with integrated device mass manufacturing cost still not at a competitive level for several key clinical applications. Lab-on-PCB is currently considered as a candidate technology addressing this issue, owing to its intuitive compatibility with electronics, seamless integration of electrochemical biosensors and the extensive experience regarding industrial manufacturing processes. Inkjet-printing in particular is a compatible fabrication method, widening the range of electronic materials available and thus enabling seamlessly integrated ultrasensitive electronic detection. To this end, in this work stable pseudo-reference electrodes are fabricated for the first time by means of commercial inkjet-printing on a PCB-integrated electrochemical biosensing platform. SEM and XPS analysis are employed to characterize the electrodes' structure and composition and identify any special characteristics, compared to published work on alternative substrates. Additionally, this paper analyzes integrated reference electrodes from a new perspective, focusing mainly on their characteristics in real-life operation: chemical sintering as opposed to high budget thermal one, stability under continuous flow, pH dependency and bias stress effects on electrode instability, a parameter often overlooked in electrochemical biosensors.
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http://dx.doi.org/10.1038/s41598-020-74340-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7554035PMC
October 2020

Electrochemical ELISA Protein Biosensing in Undiluted Serum Using a Polypyrrole-Based Platform.

Sensors (Basel) 2020 May 18;20(10). Epub 2020 May 18.

Department of Electronic & Electrical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK.

An electrochemical enzyme-linked immunosorbent assay (ELISA) biosensor platform using electrochemically prepared ~11 nm thick carboxylic functionalized popypyrrole film has been developed for bio-analyte measurement in undiluted serum. Carboxyl polypyrrole (PPy-COOH) film using 3-carboxy-pyrrol monomer onto comb-shaped gold electrode microarray (Au) was prepared via cyclic voltammetry (CV). The prepared Au/PPy-COOH was then utilized for electrochemical ELISA platform development by immobilizing analyte-specific antibodies. Tumor necrosis factor-alpha (TNF-α) was selected as a model analyte and detected in undiluted serum. For enhanced performance, the use of a polymeric alkaline phosphatase tag was investigated for the electrochemical ELISA. The developed platform was characterized at each step of fabrication using CV, electrochemical impedance spectroscopy and atomic force microscopy. The bioelectrodes exhibited linearity for TNF-α in the 100 pg/mL-100 ng/mL range when measured in spiked serum, with limit of detection of 78 pg/mL. The sensor showed insignificant signal disturbance from serum proteins and other biologically important proteins. The developed platform was found to be fast and specific and can be applicable for testing and measuring various biologically important protein markers in real samples.
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http://dx.doi.org/10.3390/s20102857DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7287672PMC
May 2020

Integrated Electrochemical Biosensors for Detection of Waterborne Pathogens in Low-Resource Settings.

Biosensors (Basel) 2020 Apr 13;10(4). Epub 2020 Apr 13.

Centre for Biosensors, Bioelectronics and Biodevices (C3Bio) and Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY, UK.

More than 783 million people worldwide are currently without access to clean and safe water. Approximately 1 in 5 cases of mortality due to waterborne diseases involve children, and over 1.5 million cases of waterborne disease occur every year. In the developing world, this makes waterborne diseases the second highest cause of mortality. Such cases of waterborne disease are thought to be caused by poor sanitation, water infrastructure, public knowledge, and lack of suitable water monitoring systems. Conventional laboratory-based techniques are inadequate for effective on-site water quality monitoring purposes. This is due to their need for excessive equipment, operational complexity, lack of affordability, and long sample collection to data analysis times. In this review, we discuss the conventional techniques used in modern-day water quality testing. We discuss the future challenges of water quality testing in the developing world and how conventional techniques fall short of these challenges. Finally, we discuss the development of electrochemical biosensors and current research on the integration of these devices with microfluidic components to develop truly integrated, portable, simple to use and cost-effective devices for use by local environmental agencies, NGOs, and local communities in low-resource settings.
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http://dx.doi.org/10.3390/bios10040036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7236604PMC
April 2020

Top-Down Fabricated Silicon Nanowire Arrays for Field-Effect Detection of Prostate-Specific Antigen.

ACS Omega 2018 Aug 1;3(8):8471-8482. Epub 2018 Aug 1.

Department of Informatics and Microsystem Technology, University of Applied Sciences Kaiserslautern, Amerikastrasse 1, 66482 Zweibrücken, Germany.

Highly sensitive electrical detection of biomarkers for the early stage screening of cancer is desired for future, ultrafast diagnostic platforms. In the case of prostate cancer (PCa), the prostate-specific antigen (PSA) is of prime interest and its detection in combination with other PCa-relevant biomarkers in a multiplex approach is advised. Toward this goal, we demonstrate the label-free, potentiometric detection of PSA with silicon nanowire ion-sensitive field-effect transistor (Si NW-ISFET) arrays. To realize the field-effect detection, we utilized the DNA aptamer-receptors specific for PSA, which were covalently and site-specifically immobilized on Si NW-ISFETs. The platform was used for quantitative detection of PSA and the change in threshold voltage of the Si NW-ISEFTs was correlated with the concentration of PSA. Concentration-dependent measurements were done in a wide range of 1 pg/mL to 1 μg/mL, which covers the clinical range of interest. To confirm the PSA-DNA aptamer binding on the Si NW surfaces, a sandwich-immunoassay based on chemiluminescence was implemented. The electrical approach using the Si NW-ISFET platform shows a lower limit of detection and a wide dynamic range of the assay. In future, our platform should be utilized to detect multiple biomarkers in one assay to obtain more reliable information about cancer-related diseases.
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http://dx.doi.org/10.1021/acsomega.8b00990DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6644640PMC
August 2018

In-situ synthesis of 3D ultra-small gold augmented graphene hybrid for highly sensitive electrochemical binding capability.

J Colloid Interface Sci 2019 Oct 7;553:289-297. Epub 2019 Jun 7.

National Institute for Biotechnology and Genetic Engineering (NIBGE), P.O. Box No. 577, Jhang Road, Faisalabad, Pakistan. Electronic address:

The fascinating properties of graphene can be augmented with other nanomaterials to generate hybrids to design innovative applications. Contrary to the conventional methodologies, we showed a novel yet simple, in-situ, biological approach which allowed for the effective growth of gold nanostructures on graphene surfaces (3D Au [email protected]). The morphology of the obtained hybrid consisted of sheets of graphene, anchoring uniform dispersion of ultra-small gold nanostructures of about 2-8 nm diameter. Surface plasmon resonance at 380 nm confirmed the nano-regimen of the hybrid. Fourier transform infrared spectroscopy indicated the utilization of amine spacers to host gold ions leading to nucleation and growth. The exceptional positive surface potential of 55 mV suggest that the hybrid as an ideal support for electrocatalysis. Ultimately, the hybrid was found to be an efficient receptor material for electrochemical performance towards the binding of uric acid which is an important biomolecule of human metabolism. The designed material enabled the detection of uric acid concentrations as low as 30 nM. This synthesis strategy is highly suitable to design new hybrid materials with interesting morphology and outstanding properties for the identification of clinically relevant biomolecules.
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http://dx.doi.org/10.1016/j.jcis.2019.06.013DOI Listing
October 2019

Gold interdigitated triple-microelectrodes for label-free prognosticative aptasensing of prostate cancer biomarker in serum.

Biosens Bioelectron 2019 Jul 26;136:118-127. Epub 2019 Apr 26.

Centre for Biosensors, Bioelectronics and Biodevices (C3Bio) and Department of Electronic & Electrical Engineering, University of Bath, Bath, BA2 7AY, United Kingdom.

A simple, single-masked gold interdigitated triple-microelectrodes biosensor is presented by taking the advantage of an effective self-assembled monolayer (SAM) using an amino-silanization technique for the early detection of a prostate cancer's biomarker, the prostate-specific antigen (PSA). Unlike most interdigitated electrode biosensors, biorecognition happens in between the interdigitated electrodes, which enhances the sensitivity and limit of detection of the sensor. Using the Faradaic mode electrochemical impedance spectroscopy (EIS) technique to quantify the PSA antigen, the developed sensing platform demonstrates a logarithmic detection of PSA ranging from 0.5 ng/ml to 5000 ng/ml, an estimated LOD down to 0.51 ng/ml in the serum, and a good sensor's reproducibility. The sensor's detection range covers the clinical threshold value at 4 ng/ml and the crucial diagnosis 'grey zone' of 4-10 ng/ml of PSA in serum for an accurate cancer diagnosis. The selectivity test revealed an excellent discrimination of other competing proteins, with a recorded detection signals at 5 ng/ml PSA as high as 7-fold increase versus the human serum albumin (HSA) and 8-fold increase versus the human glandular kallikrein 2 (hK2). The stability test showed an acceptable stability of the aptasensor recorded at six (6) days before the detection signal started degrading below 10% of the peak detection value. The developed sensing scheme is proven to exhibit a great potential as a portable prostate cancer biosensor, also as a universal platform for bio-molecular sensing with the versatility to implement nanoparticles and other surface chemistry for various applications.
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http://dx.doi.org/10.1016/j.bios.2019.04.048DOI Listing
July 2019

NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics.

Ecology 2019 07 23;100(7):e02663. Epub 2019 Apr 23.

Xenarthrans-anteaters, sloths, and armadillos-have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, 10 anteaters, and 6 sloths. Our data set includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the southern United States, Mexico, and Caribbean countries at the northern portion of the Neotropics, to the austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n = 5,941), and Cyclopes sp. have the fewest (n = 240). The armadillo species with the most data is Dasypus novemcinctus (n = 11,588), and the fewest data are recorded for Calyptophractus retusus (n = 33). With regard to sloth species, Bradypus variegatus has the most records (n = 962), and Bradypus pygmaeus has the fewest (n = 12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other data sets of Neotropical Series that will become available very soon (i.e., Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans data set. Please cite this data paper when using its data in publications. We also request that researchers and teachers inform us of how they are using these data.
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http://dx.doi.org/10.1002/ecy.2663DOI Listing
July 2019

Extracellular Electrophysiology in the Prostate Cancer Cell Model PC-3.

Sensors (Basel) 2019 Jan 3;19(1). Epub 2019 Jan 3.

Centre for Biosensors, Bioelectronics and Biodevices (C3Bio), Department of Electronic and Electrical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK.

Although prostate cancer is one of the most common cancers in the male population, its basic biological function at a cellular level remains to be fully understood. This lack of in depth understanding of its physiology significantly hinders the development of new, targeted and more effective treatment strategies. Whilst electrophysiological studies can provide in depth analysis, the possibility of recording electrical activity in large populations of non-neuronal cells remains a significant challenge, even harder to address in the picoAmpere-range, which is typical of cellular level electrical activities. In this paper, we present the measurement and characterization of electrical activity of populations of prostate cancer cells PC-3, demonstrating for the first time a meaningful electrical pattern. The low noise system used comprises a multi-electrode array (MEA) with circular gold electrodes on silicon oxide substrates. The extracellular capacitive currents present two standard patterns: an asynchronous sporadic pattern and a synchronous quasi-periodic biphasic spike pattern. An amplitude of ±150 pA, a width between 50⁻300 ms and an inter-spike interval around 0.5 Hz characterize the quasi-periodic spikes. Our experiments using treatment of cells with Gd³⁺, known as an inhibitor for the Ca²⁺ exchanges, suggest that the quasi-periodic signals originate from Ca²⁺ channels. After adding the Gd³⁺ to a population of living PC-3 cells, their electrical activity considerably decreased; once the culture was washed, thus eliminating the Gd³⁺ containing medium and addition of fresh cellular growth medium, the PC-3 cells recovered their normal electrical activity. Cellular viability plots have been carried out, demonstrating that the PC-3 cells remain viable after the use of Gd³⁺, on the timescale of this experiment. Hence, this experimental work suggests that Ca²⁺ is significantly affecting the electrophysiological communication pattern among PC-3 cell populations. Our measuring platform opens up new avenues for real time and highly sensitive investigations of prostate cancer signalling pathways.
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http://dx.doi.org/10.3390/s19010139DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6339143PMC
January 2019

Development of an aptamer-based field effect transistor biosensor for quantitative detection of Plasmodium falciparum glutamate dehydrogenase in serum samples.

Biosens Bioelectron 2019 Jan 26;123:30-35. Epub 2018 Sep 26.

Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, 781039 Assam, India. Electronic address:

There has been a continuous strive to develop portable, stable, sensitive and low cost detection system for malaria to meet the demand of effective screening actions in developing countries where the disease is most endemic. Herein, we report an aptamer-based field effect transistor (aptaFET) biosensor, developed by using an extended gate field effect transistor with inter-digitated gold microelectrodes (IDµE) for the detection of the malaria biomarker Plasmodium falciparum glutamate dehydrogenase (PfGDH) in serum samples. A 90 mer long ssDNA aptamer (NG3) selective to PfGDH was used in the aptaFET to capture the target protein. The intrinsic surface net charge of the captured protein led to change in gate potential of the aptaFET device, which could be correlated to the concentration of the protein. This biosensor exhibited a sensitive response in broad dynamic range of 100 fM -10 nM with limits of detection of 16.7 pM and 48.6 pM in spiked buffer and serum samples, respectively. The high selectivity of the biosensor for PfGDH was verified by testing relevant analogous human and parasitic proteins on the device. Overall, the results validated the application potential of the developed aptaFET for diagnosis of both symptomatic and asymptomatic malaria.
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http://dx.doi.org/10.1016/j.bios.2018.09.085DOI Listing
January 2019

Reduced graphene-oxide transducers for biosensing applications beyond the Debye-screening limit.

Biosens Bioelectron 2019 Apr 14;130:352-359. Epub 2018 Sep 14.

Institute of Materials in Electrical Engineering 1, RWTH Aachen University, Aachen, Germany; Department of Informatics and Microsystem Technology, University of Applied Sciences Kaiserslautern, Zweibrücken, Germany. Electronic address:

In the field of label-free biosensing, various transducer materials and strategies are under investigation to overcome the Debye-screening limitation of charged biomolecules. We demonstrate an in-line, impedimetric aptasensor with reduced graphene-oxide (rGO) thin films as transducers to detect prostate specific antigens (PSA) in a physiological buffer solution. Unlike classical electrochemical impedance spectroscopy (EIS), this direct, label-free and fully-electronic biosensor approach does not need any redox markers. As specific capture molecules, short anti-PSA aptamers ensured a close binding of the target molecules to the transducer surfaces. Results showed a limit of detection smaller than 33 pM of PSA and a wide detection range from 0.033 to 330 nM fully covering the clinically relevant range of PSA (0.115-0.290 nM). This promising performance can be attributed to the bipolar electronic transport characteristics of the ultra-thin rGO layers similar to pristine graphene. The attachment of target biomolecules to the films changes the resistance of the rGO thin films. Such an in-line EIS configuration with rGO thin films opens promising prospects for biosensing beyond the Debye-screening limitation, which is a major challenge for conventional semiconductor field-effect devices towards clinical applications.
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http://dx.doi.org/10.1016/j.bios.2018.09.045DOI Listing
April 2019

A PNA-based Lab-on-PCB diagnostic platform for rapid and high sensitivity DNA quantification.

Biosens Bioelectron 2019 Jan 6;123:244-250. Epub 2018 Sep 6.

Centre for Biosensors, Bioelectronics and Biodevices (C3Bio) and Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY, UK; DxOnBoard Ltd, Carpenter House, Broad Quay, Bath BA1 1UD, UK. Electronic address:

We report the development of a Lab-on-PCB DNA diagnostic platform, exploiting peptide nucleic acid (PNA) sequences as probes. The study demonstrates the optimization and characterization of two commercial PCB manufacturing gold electroplating processes for biosensing applications. Using an optimized ratio of PNA with a spacer molecule (MCH), the lowest limit of detection (LoD) to date for PCB-based DNA biosensors of 57 fM is reported. The study also showcases a fully integrated Lab-on-PCB microsystem designed for rapid detection, which employs PCB-integrated sample delivery, achieving DNA quantification in the 0.1-100 pM range for 5 μL samples analyzed within 5 min under continuous flow. The demonstrated biosensor proves the capability of PCB-based DNA biosensors for high sensitivity and paves the way for their integration in Lab-on-PCB DNA diagnostic microsystems.
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http://dx.doi.org/10.1016/j.bios.2018.09.006DOI Listing
January 2019

Electrochemical aptasensor using optimized surface chemistry for the detection of Mycobacterium tuberculosis secreted protein MPT64 in human serum.

Biosens Bioelectron 2019 Jan 26;123:141-151. Epub 2018 Jul 26.

Department of Biology, School of Science and Technology, Nazarbayev University, Astana 010000, Kazakhstan. Electronic address:

Tuberculosis (TB) remains one of the leading causes of mortality worldwide. There is a great need for the development of diagnostic tests, which are reliable, sensitive, stable, and low cost to enable early diagnosis of TB in communities with scarce resources. This study reports the optimization and evaluation of a synthetic receptor, an aptamer, for the detection of the secreted protein MPT64, which is a highly immunogenic polypeptide of Mycobacterium tuberculosis, a causative agent of TB. The study investigates combinatorial effects of an aptamer linker and a co-adsorbent onto a gold electrode for optimal binding efficiency and reduced non-specific interactions for label-free detection of MPT64 using electrochemical impedance spectroscopy. Two types of co-adsorbents and two types of aptamer linkers were studied and high specificity and sensitivity to MPT64 was observed for a surface prepared with a thiol PEGylated aptamer HS-(CH)-OP(O)O-(CHCHO)-TTTTT-aptamer and 6-mercaptohexanol in a ratio of 1:100. The developed aptamer-based sensor was successfully used with spiked human serum sample with a limit of detection of 81 pM This work demonstrates the use of the MPT64 aptamer as a lower cost, more sustainable and stable alternative of antibodies for the development of point-of-care TB biosensors decreasing the detection time from several days or hours to thirty minutes.
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http://dx.doi.org/10.1016/j.bios.2018.07.053DOI Listing
January 2019

Electrochemical ELISA-based platform for bladder cancer protein biomarker detection in urine.

Biosens Bioelectron 2018 Oct 3;117:620-627. Epub 2018 Jul 3.

Centre for Biosensors, Bioelectronics and Biodevices (C3Bio) and Department of Electronic and Electrical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom. Electronic address:

A novel fluidic-based electrochemical ELISA platform is descried for estimation of the bladder cancer protein markers nuclear mitotic apparatus protein 1 (NUMA1) and complement factor H-related 1 (CFHR1). The platform uses an off-site chamber for a sandwich immunoassay and performs the electrochemistry on-chip in a separate chamber. The off-site matrices were connected to the sensor chip in a manner that the sensors were exposed only to the final electroactive product for signal detection, thus avoiding interference from other molecules present in the sample. Two off-site matrices using 3D polymethyl methacrylate (PMMA) sheets and 2D polycarbonate (PC) membranes modified with the desired antibodies were investigated. Antibodies for NUMA1 and CFHR1 were utilized for the immunoassay and hair comb structured gold electrodes were used for sensing. Results in 10% synthetic urine reveal that the system can detect NUMA1 and CFHR1 in the 1-100 ng/ml range with high sensitivities of 260 nA/(ng/ml) and 310 nA/(ng/ml), for NUMA1 and CFHR1, respectively; negligible interference from the diluted urine and other molecules has been observed. A fully automated fluidic prototype has also been developed to demonstrate that automation of the process and multiplexing of detection can be achieved in a small footprint benchtop device. The use of off-site matrix-based platforms paves the way towards a new generation of electrochemical immunosensors for biomarker estimation with negligible non-specific interactions and false signals in complex samples.
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http://dx.doi.org/10.1016/j.bios.2018.07.003DOI Listing
October 2018

Exploiting the signatures of nanoplasmon-exciton coupling on proton sensitive insulator-semiconductor devices for drug discovery applications.

Nanoscale 2018 Jul;10(28):13320-13328

Centre for Biosensors, Bioelectronics and Biodevices (C3Bio) and Department of Electronic & Electrical Engineering, University of Bath, BA2 7AY, UK.

Multimodal sensing methods have a great promise in biosensing applications as they can measure independently several properties that characterise the biomolecular interaction to be detected as well as providing inherent on-chip validation of the sensing signals. This work describes the mechanisms of a concept of insulator-semiconductor field-effect devices coupled with nanoplasmonic sensing as a promising technology, which can be used for a wide range of analytical sensing applications. The developed method involves coupling of the localized surface plasmons (LSPs) within gold nanoparticles (AuNPs) and excitons within pH sensitive silicon nitride (Si3N4) nanofilms for screening inhibitors of kinase, which constitute an important class of chemotherapy drugs. In parallel to this optical sensing, the pH sensitivity of silicon nitride is used to detect the release of protons associated with kinase activity. By changing the insulator and AuNPs characteristics, this work demonstrates the nanoplasmonic-exciton effects taking place, enabling the developed platform to be used for screening kinase inhibitors and as a dual mode electro-optical biosensor for routine bio/chemical sensing applications.
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http://dx.doi.org/10.1039/c8nr04540bDOI Listing
July 2018

Recent Advances in Enhancement Strategies for Electrochemical ELISA-Based Immunoassays for Cancer Biomarker Detection.

Sensors (Basel) 2018 Jun 22;18(7). Epub 2018 Jun 22.

Centre for Biosensors, Bioelectronics and Biodevices (C3Bio) and Department of Electronic & Electrical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK.

Electrochemical enzyme-linked immunosorbent assay (ELISA)-based immunoassays for cancer biomarker detection have recently attracted much interest owing to their higher sensitivity, amplification of signal, ease of handling, potential for automation and combination with miniaturized analytical systems, low cost and comparative simplicity for mass production. Their developments have considerably improved the sensitivity required for detection of low concentrations of cancer biomarkers present in bodily fluids in the early stages of the disease. Recently, various attempts have been made in their development and several methods and processes have been described for their development, amplification strategies and testing. The present review mainly focuses on the development of ELISA-based electrochemical immunosensors that may be utilized for cancer diagnosis, prognosis and therapy monitoring. Various fabrication methods and signal enhancement strategies utilized during the last few years for the development of ELISA-based electrochemical immunosensors are described.
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http://dx.doi.org/10.3390/s18072010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6069457PMC
June 2018

Capacitive malaria aptasensor using Plasmodium falciparum glutamate dehydrogenase as target antigen in undiluted human serum.

Biosens Bioelectron 2018 Oct 8;117:246-252. Epub 2018 Jun 8.

Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, 781039 Assam, India. Electronic address:

A capacitive aptasensor for detecting the malaria biomarker, Plasmodium falciparum glutamate dehydrogenase (PfGDH), directly in human serum samples developed. A thiolated ssDNA aptamer (NG3) that binds specifically to PfGDH antigen with high affinity (K= 79 nM) was used to develop the aptasensor. The aptasensor produced capacitance response at an optimized frequency of 2 Hz in a non-Faradaic electrochemical impedance based signal transduction platform. The aptasensor exhibited a wide dynamic range of 100 fM-100 nM with a limits of detection of 0.77 pM in serum samples. The interference from other predominant malarial biomarkers, namely, Plasmodium falciparum -lactate dehydrogenase and -histidine rich protein-II on the aptasensor was negligible. This PfGDH aptasensor with highly sensitive and label free detection capability has great application potential for diagnosis of asymptotic malaria and monitoring the regression of malaria during treatment regime with antimalarial drugs.
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http://dx.doi.org/10.1016/j.bios.2018.06.022DOI Listing
October 2018

Survey on helminths and protozoa of free-living Neotropical bats from Northeastern Brazil.

Acta Trop 2018 Sep 5;185:267-272. Epub 2018 Jun 5.

Department of Veterinary Medicine, Federal Rural University of Pernambuco, Recife, Pernambuco, Brazil. Electronic address:

Bats are considered important reservoirs of pathogens of veterinary and medical relevance worldwide. However, despite the increasing attention paid towards the central role of bats in the spreading of some zoonotic infections, studies on their own parasites remain patchy especially in Neotropical regions. Understanding the relationships occurring between bats and their pathogens is a crucial step to determine the implications undermining the ecology and biology of these animals. The present study aims to assess the endoparasitic fauna of Neotropical bats from Northeastern Brazil, with a particular focus on helminths and protozoa. From October 2016 to March 2017, 54 fresh faecal samples were collected in stable shelters inhabited by three different bat species (i.e., Molossus molossus, Myotis lavali and Noctilio albiventris). Samples were analysed using four different techniques (i.e., Centrifugal Sedimentation, Flotation Technique, Spontaneous Sedimentation Technique and FLOTAC). A total of 96.29% (52/54) samples were positive for at least one gastrointestinal parasite and 11 different families were identified. In particular, 63.6% (7/11) of the families were of helminths and 36.4% (4/11) of protozoa. Helminths were classified into two different classes (Nematoda and Cestoda) and seven families, whereas the four protozoa classes detected (i.e., Coccidia, Gregarinomorphe, Lobosea and Zoomastigophora) into four families. Eggs of Ancylostomatidae and Hymenolepididae were the most abundan. The findings of this present study demonstrate that Neotropical bats from Northeastern Brazil are parasitized by a wide number of parasites, and some of them may have important implications for Public Health.
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http://dx.doi.org/10.1016/j.actatropica.2018.06.002DOI Listing
September 2018

Collective electrical oscillations of a diatom population induced by dark stress.

Sci Rep 2018 04 3;8(1):5484. Epub 2018 Apr 3.

Instituto Gulbenkian de Ciência, Rua da Quinta Grande n°6, 2780-343, Oeiras, Portugal.

Diatoms are photosynthetic microalgae, a group with a major environmental role on the planet due to the biogeochemical cycling of silica and global fixation of carbon. However, they can evolve into harmful blooms through a resourceful communication mechanism, not yet fully understood. Here, we demonstrate that a population of diatoms under darkness show quasi-periodic electrical oscillations, or intercellular waves. The origin is paracrine signaling, which is a feedback, or survival, mechanism that counteracts changes in the physicochemical environment. The intracellular messenger is related to Ca ions since spatiotemporal changes in their concentration match the characteristics of the intercellular waves. Our conclusion is supported by using a Ca channel inhibitor. The transport of Ca ions through the membrane to the extracellular medium is blocked and the intercellular waves disappear. The translation of microalgae cooperative signaling paves the way for early detection and prevention of harmful blooms and an extensive range of stress-induced alterations in the aquatic ecosystem.
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http://dx.doi.org/10.1038/s41598-018-23928-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5883020PMC
April 2018

Sensitive and selective Affimer-functionalised interdigitated electrode-based capacitive biosensor for Her4 protein tumour biomarker detection.

Biosens Bioelectron 2018 Jun 21;108:1-8. Epub 2018 Feb 21.

Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY, United Kingdom. Electronic address:

A novel Affimer-functionalised interdigitated electrode-based capacitive biosensor platform was developed for detection and estimation of Her4, a protein tumour biomarker, in undiluted serum. An anti-Her4 Affimer with a C-terminal cysteine was used to create the bio-recognition layer via self-assembly on gold interdigitated electrodes for the sensor fabrication. Electrochemical impedance spectroscopy (EIS) in the absence of redox markers was used to evaluate the sensor performance by monitoring the changes in capacitance. The Affimer sensor in buffer and in undiluted serum demonstrated high sensitivity with a broad dynamic range from 1 pM to 100 nM and a limit of detection lower than 1 pM both in buffer and in serum. Furthermore, the Affimer sensor demonstrated excellent specificity with negligible interference from serum proteins, suggesting resilience to non-specific binding. The sensing ability of the present Affimer sensor in spiked undiluted serum suggests its potential for a new range of Affimer-based sensors. The fabricated Affimer sensor can thus be further adapted with other probes having affinities to other biomarkers for a new range of biosensors.
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http://dx.doi.org/10.1016/j.bios.2018.02.041DOI Listing
June 2018

Nanomaterial Fungicides: In Vitro and In Vivo Antimycotic Activity of Cobalt and Nickel Nanoferrites on Phytopathogenic Fungi.

Glob Chall 2017 Dec 27;1(9):1700041. Epub 2017 Nov 27.

Amity Center of Nanotechnology Amity University Gurgaon Haryana 122413 India.

Recent advances in engineering lead to the fabrication of nanomaterials with unique properties targeted toward specific applications. The use of nanotechnology in agriculture, in particular for plant protection and production, is an under-explored area in the research community. Fungal diseases are one of the leading causes of crop destruction and, in this context, the antifungal effect of nanoparticles of cobalt and nickel ferrite against phytopathogenic fungi is reported here. As a proof of concept, it is also shown how such nanoparticles can be used as fungicides in plants. The developed cobalt and nickel ferrite nanoparticles (CoFeO and NiFeO) are successfully tested for antimycotic activity against three plant-pathogenic fungi: , and . In addition, it is also observed that these ferrite nanoparticles reduce the incidence of wilt in capsicum. The study suggests that nanoparticles of CoFeO and NiFeO can be used as an effective fungicide in plant disease management.
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http://dx.doi.org/10.1002/gch2.201700041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6607179PMC
December 2017

Capacitive aptasensor based on interdigitated electrode for breast cancer detection in undiluted human serum.

Biosens Bioelectron 2018 Apr 8;102:106-112. Epub 2017 Nov 8.

Department of Electronic & Electrical Engineering, University of Bath, Bath BA2 7AY, United Kingdom. Electronic address:

We report the development of a simple and powerful capacitive aptasensor for the detection and estimation of human epidermal growth factor receptor 2 (HER2), a biomarker for breast cancer, in undiluted serum. The study involves the incorporation of interdigitated gold electrodes, which were used to prepare the electrochemical platform. A thiol terminated DNA aptamer with affinity for HER2 was used to prepare the bio-recognition layer via self-assembly on interdigitated gold surfaces. Non-specific binding was prevented by blocking free spaces on surface via starting block phosphate buffer saline-tween20 blocker. The sensor was characterized using cyclic voltammetry, electrochemical impedance spectroscopy (EIS), atomic force microscopy and contact angle studies. Non-Faradic EIS measurements were utilized to investigate the sensor performance via monitoring of the changes in capacitance. The aptasensor exhibited logarithmically detection of HER2 from 1pM to 100nM in both buffer and undiluted serum with limits of detection lower than 1pM. The results pave the way to develop other aptamer-based biosensors for protein biomarkers detection in undiluted serum.
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http://dx.doi.org/10.1016/j.bios.2017.11.013DOI Listing
April 2018

Biosensors for Screening Kinase Inhibitors.

Curr Top Med Chem 2017 ;17(22):2470-2481

Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY, United Kingdom.

For successful drug discovery it is important to understand the fundamentals of the underlying causes and consequences of the diseases for which the drug is being developed. One such physiological process in eukaryotic cells is protein phosphorylation, which is the main post-translational modification of proteins responsible for the onset or progression of Alzheimer's disease, diabetes and various cancers. Protein phosphorylation is facilitated by kinases and inhibitors of kinases act as drugs in controlling or curing these diseases by reducing protein phosphorylation. This review discusses the technologies capable of detecting kinase activity and screening candidate compounds to identify novel inhibitors of protein kinases.
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http://dx.doi.org/10.2174/1568026617666170531113233DOI Listing
August 2017
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