scholarly journals Spectral-Phase Interferometry Detection of Ochratoxin A via Aptamer-Functionalized Graphene Coated Glass

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 226
Author(s):  
Nikita Nekrasov ◽  
Natalya Yakunina ◽  
Averyan V. Pushkarev ◽  
Alexey V. Orlov ◽  
Ivana Gadjanski ◽  
...  
Keyword(s):  
Small Molecules ◽  
Ochratoxin A ◽  
Direct Method ◽  
Low Cost ◽  
Optical Signal ◽  
Spectral Phase ◽  
Urea Solution ◽  
Label Free ◽  
Label Free Detection ◽  
Interferometric Sensor

In this work, we report a novel method of label-free detection of small molecules based on direct observation of interferometric signal change in graphene-modified glasses. The interferometric sensor chips are fabricated via a conventional wet transfer method of CVD-grown graphene onto the glass coverslips, lowering the device cost and allowing for upscaling the sensor fabrication. For the first time, we report the use of graphene functionalized by the aptamer as the bioreceptor, in conjunction with Spectral-Phase Interferometry (SPI) for detection of ochratoxin A (OTA). In a direct assay with an OTA-specific aptamer, we demonstrated a quick and significant change of the optical signal in response to the maximum tolerable level of OTA concentration. The sensor regeneration is possible in urea solution. The developed platform enables a direct method of kinetic analysis of small molecules using a low-cost optical chip with a graphene-aptamer sensing layer.

scholarly journals MALDIViz: A Comprehensive Informatics Tool for MALDI-MS Data Visualization and Analysis

2017 ◽  
Vol 22 (10) ◽  
pp. 1246-1252 ◽  
Author(s):  
Kishore Kumar Jagadeesan ◽  
Simon Ekström
Keyword(s):  
Mass Spectrometry ◽  
High Throughput ◽  
High Throughput Screening ◽  
Web Application ◽  
Low Cost ◽  
Maldi Ms ◽  
Ionization Mass ◽  
Label Free ◽  
Label Free Detection ◽  
R Shiny

Recently, mass spectrometry (MS) has emerged as an important tool for high-throughput screening (HTS) providing a direct and label-free detection method, complementing traditional fluorescent and colorimetric methodologies. Among the various MS techniques used for HTS, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) provides many of the characteristics required for high-throughput analyses, such as low cost, speed, and automation. However, visualization and analysis of the large datasets generated by HTS MALDI-MS can pose significant challenges, especially for multiparametric experiments. The datasets can be generated fast, and the complexity of the experimental data (e.g., screening many different sorbent phases, the sorbent mass, and the load, wash, and elution conditions) makes manual data analysis difficult. To address these challenges, a comprehensive informatics tool called MALDIViz was developed. This tool is an R-Shiny-based web application, accessible independently of the operating system and without the need to install any program locally. It has been designed to facilitate easy analysis and visualization of MALDI-MS datasets, comparison of multiplex experiments, and export of the analysis results to high-quality images.

scholarly journals A Simple Displacement Aptamer Assay on Resistive Pulse Sensor for Small Molecule Detection

2020 ◽  
Author(s):  
Rhushabh Maugi ◽  
bernadette gamble ◽  
david bunka ◽  
Mark Platt
Keyword(s):  
Small Molecules ◽  
Small Molecule ◽  
Label Free ◽  
Resistive Pulse ◽  
Pulse Sensor ◽  
Label Free Detection ◽  
Ssdna Aptamer ◽  
Aptamer Assay ◽  
Small Molecule Detection ◽  
Surface Changes

A universal aptamer-based sensing strategy is proposed using DNA modified nanocarriers and Resistive Pulse Sensing for the rapid and label free detection of small molecules. The surface of a magnetic nanocarrier was first modified with a ssDNA aka linker which is designed to be partially complimentary in sequence to a ssDNA aptamer. The aptamer and linker form a stable dsDNA complex on the nanocarriers surface. Upon the addition of the target molecule, a conformational change takes place where the aptamer preferentially binds to the target over the linker; causing the aptamer to be released into solution. The RPS measures the change in velocity of the nanocarrier as its surface changes from dsDNA to ssDNA, and its velocity is used as a proxy for the concentration of the target. We illustrate the versatility of the assay by demonstrating the detection of the antibiotic Moxifloxacin, and chemotherapeutics Imatinib and Irinotecan.

scholarly journals Aptamer Functionalized Lipid Multilayer Gratings for Label-Free Analyte Detection

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2433
Author(s):  
Plengchart Prommapan ◽  
Nermina Brljak ◽  
Troy W. Lowry ◽  
David Van Winkle ◽  
Steven Lenhert
Keyword(s):  
Lipid Composition ◽  
Optical Biosensor ◽  
Optical Signal ◽  
Dna Aptamer ◽  
Critical Parameters ◽  
Label Free ◽  
Scale Thickness ◽  
Label Free Detection ◽  
Analyte Detection ◽  
Micrometer Scale

Lipid multilayer gratings are promising optical biosensor elements that are capable of transducing analyte binding events into changes in an optical signal. Unlike solid state transducers, reagents related to molecular recognition and signal amplification can be incorporated into the lipid grating ink volume prior to fabrication. Here we describe a strategy for functionalizing lipid multilayer gratings with a DNA aptamer for the protein thrombin that allows label-free analyte detection. A double cholesterol-tagged, double-stranded DNA linker was used to attach the aptamer to the lipid gratings. This approach was found to be sufficient for binding fluorescently labeled thrombin to lipid multilayers with micrometer-scale thickness. In order to achieve label-free detection with the sub-100 nm-thick lipid multilayer grating lines, the binding affinity was improved by varying the lipid composition. A colorimetric image analysis of the light diffracted from the gratings using a color camera was then used to identify the grating nanostructures that lead to an optimal signal. Lipid composition and multilayer thickness were found to be critical parameters for the signal transduction from the aptamer functionalized lipid multilayer gratings.

scholarly journals Paper-based fluorogenic RNA aptamer sensors for label-free detection of small molecules

2020 ◽  
Vol 12 (21) ◽  
pp. 2674-2681
Author(s):  
Fatemeh Shafiei ◽  
Kathleen McAuliffe ◽  
Yousef Bagheri ◽  
Zhining Sun ◽  
Qikun Yu ◽  
...  
Keyword(s):  
Small Molecules ◽  
Rapid Detection ◽  
Rna Aptamer ◽  
Label Free ◽  
Target Analytes ◽  
Label Free Detection

A paper-based portable fluorogenic RNA sensor for the selective, sensitive, and rapid detection of target analytes.

scholarly journals Electrochemical DNA Detection Methods to Measure Circulating Tumour DNA for Enhanced Diagnosis and Monitoring of Cancer

Proceedings ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 15
Author(s):  
Bukola Attoye ◽  
Matthew Baker ◽  
Chantevy Pou ◽  
Fiona Thomson ◽  
Damion K. Corrigan
Keyword(s):  
Point Of Care ◽  
Low Cost ◽  
Detection Methods ◽  
Clinical Samples ◽  
Label Free ◽  
Ambient Conditions ◽  
Liquid Biopsies ◽  
Current Time ◽  
Electrochemical Approach ◽  
Label Free Detection

Liquid biopsies are becoming increasingly important as a potential replacement for existing biopsy procedures which can be invasive, painful and compromised by tumour heterogeneity. This paper reports a simple electrochemical approach tailored towards point-of-care cancer detection and treatment monitoring from biofluids using a label-free detection strategy. The mutations under test were the KRAS G12D and G13D mutations, which are both important in the development and progression of many human cancers and which have a presence that correlates with poor outcomes. These common circulating tumour markers were investigated in clinical samples and amplified by standard and specialist PCR methodologies for subsequent electrochemical detection. Following pre-treatment of the sensor to present a clean surface, DNA probes developed specifically for detection of the KRAS G12D and G13D mutations were immobilized onto low-cost carbon electrodes using diazonium chemistry and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide coupling. Following the functionalisation of the sensor, it was possible to sensitively and specifically detect a mutant KRAS G13D PCR product against a background of wild-type KRAS DNA from the representative cancer sample. Our findings give rise to the basis of a simple and very low-cost system for measuring ctDNA biomarkers in patient samples. The current time to result of the system was 3.5 h with considerable scope for optimisation, and it already compares favourably to the UK National Health Service biopsy service where patients can wait weeks for their result. This paper reports the technical developments we made in the production of consistent carbon surfaces for functionalisation, assay performance data for KRAS G13D and detection of PCR amplicons under ambient conditions.

scholarly journals Super-Nernstian ion sensitive field-effect transistor exploiting charge screening in WSe2/MoS2 heterostructure

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Sooraj Sanjay ◽  
Mainul Hossain ◽  
Ankit Rao ◽  
Navakanta Bhat
Keyword(s):  
Field Effect ◽  
Field Effect Transistors ◽  
Point Of Care ◽  
Low Cost ◽  
Ph Sensor ◽  
Detection Sensitivity ◽  
Label Free ◽  
Back Gate ◽  
Dielectric Thickness ◽  
Label Free Detection

AbstractIon-sensitive field-effect transistors (ISFETs) have gained a lot of attention in recent times as compact, low-cost biosensors with fast response time and label-free detection. Dual gate ISFETs have been shown to enhance detection sensitivity beyond the Nernst limit of 59 mV pH−1 when the back gate dielectric is much thicker than the top dielectric. However, the thicker back-dielectric limits its application for ultrascaled point-of-care devices. In this work, we introduce and demonstrate a pH sensor, with WSe2(top)/MoS2(bottom) heterostructure based double gated ISFET. The proposed device is capable of surpassing the Nernst detection limit and uses thin high-k hafnium oxide as the gate oxide. The 2D atomic layered structure, combined with nanometer-thick top and bottom oxides, offers excellent scalability and linear response with a maximum sensitivity of 362 mV pH−1. We have also used technology computer-aided (TCAD) simulations to elucidate the underlying physics, namely back gate electric field screening through channel and interface charges due to the heterointerface. The proposed mechanism is independent of the dielectric thickness that makes miniaturization of these devices easier. We also demonstrate super-Nernstian behavior with the flipped MoS2(top)/WSe2(bottom) heterostructure ISFET. The results open up a new pathway of 2D heterostructure engineering as an excellent option for enhancing ISFET sensitivity beyond the Nernst limit, for the next-generation of label-free biosensors for single-molecular detection and point-of-care diagnostics.

Double stranded DNA-templated copper nanoclusters as a novel fluorescent probe for label-free detection of rutin

2019 ◽  
Vol 11 (28) ◽  
pp. 3584-3589 ◽  
Author(s):  
Yanqiong Lai ◽  
Xia Teng ◽  
Yanli Zhang ◽  
Hongbin Wang ◽  
Pengfei Pang ◽  
...  
Keyword(s):  
Fluorescent Probe ◽  
Low Cost ◽  
Label Free ◽  
Copper Nanoclusters ◽  
Double Stranded Dna ◽  
Label Free Detection

In this study, we developed a simple, sensitive, low-cost and label-free method to detect rutin by using double-stranded DNA-templated copper nanoclusters (dsDNA-CuNCs) as a fluorescent probe.

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