scholarly journals Aptamer Conformation Switching-Induced Two-Stage Amplification for Fluorescent Detection of Proteins

Sensors ◽  
2018 ◽  
Vol 19 (1) ◽  
pp. 77 ◽  
Author(s):  
Qiao Yu ◽  
Fenfen Zhai ◽  
Hong Zhou ◽  
Zonghua Wang
Keyword(s):  
Molecular Beacon ◽  
Limit Of Detection ◽  
Low Cost ◽  
Dna Aptamer ◽  
Fluorescent Detection ◽  
Fluorescence Signal ◽  
Sensing Platform ◽  
Low Concentrations ◽  
Diagnostic Applications ◽  
Recycling Amplification

Basing on the conformation change of aptamer caused by proteins, a simple and sensitive protein fluorescent assay strategy is proposed, which is assisted by the isothermal amplification reaction of polymerase and nicking endonuclease. In the presence of platelet-derived growth factor (PDGF-BB), the natural conformation of a DNA aptamer would change into a Y-shaped complex, which could hybridize with a molecular beacon (MB) and form a DNA duplex, leading to the open state of the MB and generating a fluorescence signal. Subsequently, with further assistance of isothermal recycling amplification strategies, the designed aptamer sensing platform showed an increment of fluorescence. As a benefit of this amplified strategy, the limit of detection (LOD) was lowered to 0.74 ng/mL, which is much lower than previous reports. This strategy not only offers a new simple, specific, and efficient platform to quantify the target protein in low concentrations, but also shows a powerful approach without multiple washing steps, as well as a precious implementation that has the potential to be integrated into portable, low-cost, and simplified devices for diagnostic applications.

scholarly journals Development of a Cost-Effective Sensing Platform for Monitoring Phosphate in Natural Waters

Chemosensors ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 57 ◽  
Author(s):  
Andrew Donohoe ◽  
Gareth Lacour ◽  
Peter McCluskey ◽  
Dermot Diamond ◽  
Margaret McCaul
Keyword(s):  
Natural Waters ◽  
Limit Of Detection ◽  
Low Cost ◽  
Unit Cost ◽  
High Standard ◽  
Cost Effective ◽  
Remote Access ◽  
Sampling Location ◽  
Sensing Platform

A sensing platform for the in situ, real-time analysis of phosphate in natural waters has been realised using a combination of microfluidics, colorimetric reagent chemistries, low-cost LED-based optical detection and wireless communications. Prior to field deployment, the platform was tested over a period of 55 days in the laboratory during which a total of 2682 autonomous measurements were performed (854 each of sample, high standard and baseline, and 40 × 3 spiked solution measurements). The platform was subsequently field-deployed in a freshwater stream at Lough Rea, Co., Galway, Ireland, to track changes in phosphate over a five day period. During this deployment, 165 autonomous measurements (55 each of sample, high standard, and baseline) were performed and transmitted via general packet radio service (GPRS) to a web interface for remote access. Increases in phosphate levels at the sampling location coincident with rainfall events (min 1.45 µM to max 10.24 µM) were detected during the deployment. The response was found to be linear up to 50 µM PO43−, with a lower limit of detection (LOD) of 0.09 µM. Laboratory and field data suggest that despite the complexity of reagent-based analysers, they are reasonably reliable in remote operation, and offer the best opportunity to provide enhanced in situ chemical sensing capabilities. Modifications that could further improve the reliability and scalability of these platforms while simultaneously reducing the unit cost are discussed.

scholarly journals Breaking the barrier to biomolecule limit-of-detection via 3D printed multi-length-scale graphene-coated electrodes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Md. Azahar Ali ◽  
Chunshan Hu ◽  
Bin Yuan ◽  
Sanjida Jahan ◽  
Mohammad S. Saleh ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
High Surface ◽  
High Surface Area ◽  
Length Scale ◽  
Graphene Nanoflakes ◽  
Sensing Platform ◽  
Low Concentrations ◽  
Ultralow Concentrations ◽  
3D Printed ◽  
Coated Electrodes

AbstractSensing of clinically relevant biomolecules such as neurotransmitters at low concentrations can enable an early detection and treatment of a range of diseases. Several nanostructures are being explored by researchers to detect biomolecules at sensitivities beyond the picomolar range. It is recognized, however, that nanostructuring of surfaces alone is not sufficient to enhance sensor sensitivities down to the femtomolar level. In this paper, we break this barrier/limit by introducing a sensing platform that uses a multi-length-scale electrode architecture consisting of 3D printed silver micropillars decorated with graphene nanoflakes and use it to demonstrate the detection of dopamine at a limit-of-detection of 500 attomoles. The graphene provides a high surface area at nanoscale, while micropillar array accelerates the interaction of diffusing analyte molecules with the electrode at low concentrations. The hierarchical electrode architecture introduced in this work opens the possibility of detecting biomolecules at ultralow concentrations.

scholarly journals Analytical Molecular Diagnosis of Cervical Cancer via Paper Microfluidic Chip

Proceedings ◽  
2018 ◽  
Vol 2 (25) ◽  
pp. 1556
Author(s):  
Melike Karakaya
Keyword(s):  
Microfluidic Chip ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Extraction Process ◽  
Single Step ◽  
Enzymatic Amplification ◽  
Whole Process ◽  
Low Concentrations ◽  
Paper Microfluidic

In this work, we focused on the development of a novel point of care (POC) paper-based analytical microfluidic chip. The system has been developed for paper-based extraction, non-enzymatic amplification and electroanalytical detection of human papillomavirus (HPV). The device comprises paper extraction support material as well as paper-based detection tool. Herein, a special DNA modification method has been utilized to allow non-enzymatic amplification by using microbeads and silver nanoparticles labeled primers. The device is capable of extracting more than 10–100 copies per mL of DNA approximately in 15 min along with a single step extraction process from patient samples. In addition, it is able to detect low concentrations taking just less than 10 min with high selectivity to HPV kinds of 16&18. It only takes the low-cost point of care device less than 40 min with a low limit of detection (LOD) to complete the whole process.

Highly Sensitive Detection of miRNA-155 Using Molecular Beacon-Functionalized Monolayer MoS2 Nanosheet Probes with Duplex-Specific Nuclease-Mediated Signal Amplification

2021 ◽  
Vol 17 (6) ◽  
pp. 1034-1043
Author(s):  
Ying Liu ◽  
Zhou Ding ◽  
Jingjing Zhang ◽  
Chunyuan Song ◽  
Le Zhang ◽  
...  
Keyword(s):  
Human Serum ◽  
Fluorescent Probe ◽  
Molecular Beacon ◽  
Limit Of Detection ◽  
Fluorescence Signal ◽  
Linear Calibration ◽  
Highly Sensitive ◽  
Relative Standard ◽  
Highly Sensitive Detection ◽  
Fluorescence Amplification

MicroRNA-155 (miRNA-155) as a characteristic myeloma-associated biomarker exhibits significant potential application in the diagnosis of multiple myeloma (MM). In this paper, a novel type of molecular beacon (MB)-functionalized monolayer MoS2 nanosheet probe was proposed as fluorescent probe for high-sensitive assays of miRNA-155that uses a duplexspecificnuclease (DSN) enzyme to amplify the fluorescence signal. The preparation and detection conditions of the fluorescent probes were optimized in some aspects, such as the concentration of MoS2 (0.80 μM) and DSN (0.2 U), and the incubation time of DSN (30 min). The probesexhibited a sensitive fluorescence response to miRNA-155 and the fluorescence signal of the assay was significantly amplified by the cleavage of DSN. The relationship between F/F0 and logC miRNA follows a linear calibration curve, and the limit of detection (LOD) of miRNA-155 in 10% human serum is calculated to be 10.96 fM based on this relationship. The good performance and fluorescence amplification effect of the fluorescent probe were confirmed by studying the recovery of miRNA-155 in 10% human serum, which was ranged from 98.32% to 106.3% with a relative standard deviation of less than 4.14%. Besides, the high expression of miRNA-155 in clinic blood of MM patients was sensitively distinguished from healthy peoples by using the proposed probes. The proposed novel fluorescent probe based on the DSN can be used to detect miRNA-155 in human serum and provide a potential, convenient and reliable tool for diagnosis of MM.

scholarly journals Simple and Label-Free Fluorescent Detection of Melamine Based on Melamine–Thymine Recognition

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2968 ◽  
Author(s):  
Hualin Yang ◽  
Jiujun Wang ◽  
Qinghua Wu ◽  
Yun Wang ◽  
Li Li ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Chain Structure ◽  
Sybr Green ◽  
Sybr Green I ◽  
Fluorescent Detection ◽  
Fluorescence Signal ◽  
Label Free ◽  
Protein Levels ◽  
Fluorescent Method ◽  
Milk Adulteration

In the past few years, melamine has been illegally added into dairy products to increase the apparent crude protein levels. If humans or animals drink the milk adulteration of melamine, it can form insoluble melamine–cyanurate crystals in their kidneys which causes kidney damage or even death. In the present work, we constructed a simple and label-free fluorescent method for melamine detection based on melamine-thymine recognition. SYBR Green I was utilized as a reporter for this method as it did not require any modification or expensive equipment. In the absence of melamine, polythymine DNA was digested by Exo I, which caused a decrease in the fluorescence signal. In the presence of melamine, the polythymine DNA was able to fold into a double chain structure, however this was done with the help of T-melamine-T mismatches to prevent degradation. Then, the SYBR Green I combined with the double-stranded DNA to result in an intense fluorescence signal. The limit of detection in this method was 1.58 μM, which satisfied the FDA standards. This method also had a good linear relationship within the range of 10–200 μM. In addition, this new method has a good selectivity to distinguish melamine from the component of milk. As a result, we developed a simple and highly selectivity method for melamine detection.

scholarly journals Paper-based aptamer-antibody biosensor for gluten detection in a deep eutectic solvent (DES)

2021 ◽  
Author(s):  
Rossella Svigelj ◽  
Nicolò Dossi ◽  
Cristian Grazioli ◽  
Rosanna Toniolo
Keyword(s):  
Dynamic Range ◽  
Limit Of Detection ◽  
Low Cost ◽  
Deep Eutectic Solvent ◽  
Electrochemical Sensing ◽  
Sensing Platform ◽  
Screen Printed Carbon Electrode ◽  
Highly Sensitive ◽  
Rapid Tests

AbstractPaper has been widely employed as cheap material for the development of a great number of sensors such as pregnancy tests, strips to measure blood sugar, and COVID-19 rapid tests. The need for new low-cost analytical devices is growing, and consequently the use of these platforms will be extended to different assays, both for the final consumer and within laboratories. This work describes a paper-based electrochemical sensing platform that uses a paper disc conveniently modified with recognition molecules and a screen-printed carbon electrode (SPCE) to achieve the detection of gluten in a deep eutectic solvent (DES). This is the first method coupling a paper biosensor based on aptamers and antibodies with the DES ethaline. Ethaline proved to be an excellent extraction medium allowing the determination of very low gluten concentrations. The biosensor is appropriate for the determination of gluten with a limit of detection (LOD) of 0.2 mg L−1 of sample; it can detect gluten extracted in DES with a dynamic range between 0.2 and 20 mg L−1 and an intra-assay coefficient of 10.69%. This approach can be of great interest for highly gluten-sensitive people, who suffer from ingestion of gluten quantities well below the legal limit, which is 20 parts per million in foods labeled gluten-free and for which highly sensitive devices are essential. Graphical abstract

scholarly journals Whole-Cell Biosensor with Tunable Limit of Detection Enables Low-Cost Agglutination Assays for Medical Diagnostic Applications

ACS Sensors ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 370-378 ◽  
Author(s):  
Nicolas Kylilis ◽  
Pinpunya Riangrungroj ◽  
Hung-En Lai ◽  
Valencio Salema ◽  
Luis Ángel Fernández ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Low Cost ◽  
Whole Cell ◽  
Medical Diagnostic ◽  
Diagnostic Applications ◽  
Whole Cell Biosensor ◽  
Cell Biosensor

scholarly journals A rapid, accurate, scalable, and portable testing system for COVID-19 diagnosis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guanhua Xun ◽  
Stephan Thomas Lane ◽  
Vassily Andrew Petrov ◽  
Brandon Elliott Pepa ◽  
Huimin Zhao
Keyword(s):  
Limit Of Detection ◽  
Low Cost ◽  
High Volume ◽  
N Gene ◽  
Testing System ◽  
Target Sequence ◽  
One Pot ◽  
Sequence Detection ◽  
Highly Sensitive ◽  
Speed Accuracy

AbstractThe need for rapid, accurate, and scalable testing systems for COVID-19 diagnosis is clear and urgent. Here, we report a rapid Scalable and Portable Testing (SPOT) system consisting of a rapid, highly sensitive, and accurate assay and a battery-powered portable device for COVID-19 diagnosis. The SPOT assay comprises a one-pot reverse transcriptase-loop-mediated isothermal amplification (RT-LAMP) followed by PfAgo-based target sequence detection. It is capable of detecting the N gene and E gene in a multiplexed reaction with the limit of detection (LoD) of 0.44 copies/μL and 1.09 copies/μL, respectively, in SARS-CoV-2 virus-spiked saliva samples within 30 min. Moreover, the SPOT system is used to analyze 104 clinical saliva samples and identified 28/30 (93.3% sensitivity) SARS-CoV-2 positive samples (100% sensitivity if LoD is considered) and 73/74 (98.6% specificity) SARS-CoV-2 negative samples. This combination of speed, accuracy, sensitivity, and portability will enable high-volume, low-cost access to areas in need of urgent COVID-19 testing capabilities.

scholarly journals Rapid and Sensitive Detection of miRNA Based on AC Electrokinetic Capacitive Sensing for Point-of-Care Applications

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 3985
Author(s):  
Nan Wan ◽  
Yu Jiang ◽  
Jiamei Huang ◽  
Rania Oueslati ◽  
Shigetoshi Eda ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Clinical Diagnostics ◽  
Detection Methods ◽  
Capacitive Sensing ◽  
Application Potential ◽  
Mirna Detection ◽  
Mirna 25 ◽  
Low Sensitivity

A sensitive and efficient method for microRNAs (miRNAs) detection is strongly desired by clinicians and, in recent years, the search for such a method has drawn much attention. There has been significant interest in using miRNA as biomarkers for multiple diseases and conditions in clinical diagnostics. Presently, most miRNA detection methods suffer from drawbacks, e.g., low sensitivity, long assay time, expensive equipment, trained personnel, or unsuitability for point-of-care. New methodologies are needed to overcome these limitations to allow rapid, sensitive, low-cost, easy-to-use, and portable methods for miRNA detection at the point of care. In this work, to overcome these shortcomings, we integrated capacitive sensing and alternating current electrokinetic effects to detect specific miRNA-16b molecules, as a model, with the limit of detection reaching 1.0 femto molar (fM) levels. The specificity of the sensor was verified by testing miRNA-25, which has the same length as miRNA-16b. The sensor we developed demonstrated significant improvements in sensitivity, response time and cost over other miRNA detection methods, and has application potential at point-of-care.

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