scholarly journals A Label-Free Fluorescent DNA Machine for Sensitive Cyclic Amplification Detection of ATP

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2408
Author(s):  
Jingjing Zhang ◽  
Jialun Han ◽  
Shehong Feng ◽  
Chaoqun Niu ◽  
Chen Liu ◽  
...  
Keyword(s):  
Human Urine ◽  
Limit Of Detection ◽  
Logic Gates ◽  
Fluorescent Label ◽  
Label Free ◽  
Background Signal ◽  
Detection Range ◽  
Signal Suppression ◽  
Dna Machine ◽  
Recycling Amplification

In this study, a target recycled amplification, background signal suppression, label-free fluorescent, enzyme-free deoxyribonucleic acid (DNA) machine was developed for the detection of adenosine triphosphate (ATP) in human urine. ATP and DNA fuel strands (FS) were found to trigger the operation of the DNA machine and lead to the cyclic multiplexing of ATP and the release of single stranded (SS) DNA. Double-stranded DNA (dsDNA) was formed on graphene oxide (GO) from the combination of SS DNA and complementary strands (CS′). These double strands then detached from the surface of the GO and in the process interacted with PicoGreen dye resulting in amplifying fluorescence intensity. The results revealed that the detection range of the DNA machine is from 100 to 600 nM (R2 = 0.99108) with a limit of detection (LOD) of 127.9 pM. A DNA machine circuit and AND-NOT-AND-OR logic gates were successfully constructed, and the strategy was used to detect ATP in human urine. With the advantage of target recycling amplification and GO suppressing background signal without fluorescent label and enzyme, this developed strategy has great potential for sensitive detection of different proteins and small molecules.

scholarly journals Label-Free Electrochemical Biosensor Based on Au@MoS₂–PANI for Escherichia coli Detection

Chemosensors ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 49
Author(s):  
Pushap Raj ◽  
Man Hwan Oh ◽  
Kyudong Han ◽  
Tae Yoon Lee
Keyword(s):  
Escherichia Coli ◽  
Bacterial Infections ◽  
Limit Of Detection ◽  
Bacterial Pathogens ◽  
Cost Effective ◽  
Covalent Immobilization ◽  
Label Free ◽  
Self Assembled Monolayer ◽  
Detection Range ◽  
Linear Detection

Bacterial infections have become a significant challenge in terms of public health, the food industry, and the environment. Therefore, it is necessary to address these challenges by developing a rapid, cost-effective, and easy-to-use biosensor for early diagnosis of bacterial pathogens. Herein, we developed a simple, label-free, and highly sensitive immunosensor based on electrochemical detection using the Au@MoS₂–PANI nanocomposite. The conductivity of the glassy carbon electrode is greatly enhanced using the Au@MoS₂–PANI nanocomposite and a self-assembled monolayer of mercaptopropionic acid on the gold nanoparticle surface was employed for the covalent immobilization of antibodies to minimize the nonspecific adsorption of bacterial pathogens on the electrode surface. The biosensor established a high selectivity and sensitivity with a low limit of detection of 10 CFU/mL, and detected Escherichia coli within 30 min. Moreover, the developed biosensor demonstrated a good linear detection range, practical utility in urine samples, and electrode regenerative studies.

Target-triggered cascade recycling amplification for label-free detection of microRNA and molecular logic operations

2016 ◽  
Vol 52 (2) ◽  
pp. 402-405 ◽  
Author(s):  
Sai Bi ◽  
Jiayan Ye ◽  
Ying Dong ◽  
Haoting Li ◽  
Wei Cao
Keyword(s):  
Logic Gates ◽  
Logic Circuits ◽  
Label Free ◽  
Chemiluminescence Detection ◽  
Molecular Logic ◽  
Label Free Detection ◽  
Molecular Scale ◽  
Ultrahigh Sensitivity ◽  
Recycling Amplification ◽  
Logic Operations

A cascade recycling amplification (CRA) that implements cascade logic circuits with feedback amplification function is developed for label-free chemiluminescence detection of microRNA-122 with an ultrahigh sensitivity of 0.82 fM and excellent specificity, which is applied to construct a series of molecular-scale two-input logic gates by using microRNAs as inputs and CRA products as outputs.

scholarly journals Label-Free Direct Detection of Saxitoxin Based on a Localized Surface Plasmon Resonance Aptasensor

Toxins ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 274 ◽  
Author(s):  
Su-Ji Ha ◽  
Jin-Ho Park ◽  
Bobin Lee ◽  
Min-Gon Kim
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Localized Surface Plasmon Resonance ◽  
Limit Of Detection ◽  
Direct Detection ◽  
Localized Surface Plasmon ◽  
Label Free ◽  
Health Food ◽  
Detection Range

Seafood is an emerging health food, and interest in improving the quality of seafood is increasing. Saxitoxin (STX) is a neurotoxin produced by marine dinoflagellates that is accumulated in seafood. It can block the neuronal transmission between nerves and muscle cell membranes, resulting in the disturbance of neuromuscular transmission and subsequent voluntary muscle paralysis. Here, we developed a new aptamer for the detection of STX using graphene oxide–systematic evolution of ligands by exponential enrichment (GO-SELEX). Furthermore, we confirmed sensitivity and selectivity of the developed aptamer specific to STX using a localized surface plasmon resonance (LSPR) sensor. The sensing chip was fabricated by fixing the new STX aptamer immobilized on the gold nanorod (GNR) substrate. The STX LSPR aptasensor showed a broad, linear detection range from 5 to 10,000 μg/L, with a limit of detection (LOD) of 2.46 μg/L (3σ). Moreover, it was suitable for the detection of STX (10, 100, and 2000 μg/L) in spiked mussel samples and showed a good recovery rate (96.13–116.05%). The results demonstrated that the new STX aptamer-modified GNR chip was sufficiently sensitive and selective to detect STX and can be applied to real samples as well. This LSPR aptasensor is a simple, label-free, cost-effective sensing system with a wide detectable range.

Exonuclease-assisted target recycling amplification for label-free chemiluminescence assay and molecular logic operations

2017 ◽  
Vol 53 (90) ◽  
pp. 12201-12204 ◽  
Author(s):  
Yongcun Yan ◽  
Shuzhen Yue ◽  
Tingting Zhao ◽  
Baoyu Luo ◽  
Sai Bi
Keyword(s):  
Logic Gates ◽  
Label Free ◽  
Chemiluminescence Detection ◽  
Target Recycling ◽  
Chemiluminescence Assay ◽  
Molecular Logic ◽  
Molecular Logic Gates ◽  
Recycling Amplification ◽  
Logic Operations ◽  
Amplification Strategy

A versatile exonuclease-assisted target recycling amplification strategy is demonstrated to achieve label-free chemiluminescence detection of DNA and construction of a series of two-input molecular logic gates.

scholarly journals A Label-Free Fluorescent AND Logic Gate Aptasensor for Sensitive ATP Detection

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3281 ◽  
Author(s):  
Jingjing Zhang ◽  
Chunzheng Yang ◽  
Chaoqun Niu ◽  
Chen Liu ◽  
Xuepin Cai ◽  
...  
Keyword(s):  
Deoxyribonucleic Acid ◽  
Limit Of Detection ◽  
Low Cost ◽  
Logic Gate ◽  
Label Free ◽  
Detection Range ◽  
Sensitivity Range ◽  
Highly Sensitive ◽  
Input Signals ◽  
Atp Detection

In this study, a label-free fluorescent, enzyme-free, simple, highly sensitive AND logic gate aptasensor was developed for the detection of adenosine triphosphate (ATP). Double-stranded deoxyribonucleic acid (DNA) with cohesive ends was attached to graphene oxide (GO) to form an aptasensor probe. ATP and single-stranded DNA were used as input signals. Fluorescence intensity of PicoGreen dye was used as an output signal. The biosensor-related performances, including the logic gate construction, reaction time, linearity, sensitivity, and specificity, were investigated and the results showed that an AND logic gate was successfully constructed. The ATP detection range was found to be 20 to 400 nM (R2 = 0.9943) with limit of detection (LOD) of 142.6 pM, and the sensitivity range was 1.846 × 106 to 2.988 × 106 M−1. This method for the detection of ATP has the characteristics of being simple, low cost, and highly sensitive.

scholarly journals A Compact Detection Platform Based on Gradient Guided-Mode Resonance for Colorimetric and Fluorescence Liquid Assay Detection

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2797
Author(s):  
Jing-Jhong Gao ◽  
Ching-Wei Chiu ◽  
Kuo-Hsing Wen ◽  
Cheng-Sheng Huang
Keyword(s):  
Limit Of Detection ◽  
Detection System ◽  
Fluorescence Emission ◽  
Assay Sensitivity ◽  
Detection Range ◽  
Current Form ◽  
Guided Mode ◽  
Spectral Detection ◽  
Guided Mode Resonance ◽  
Colorimetric Assays

This paper presents a compact spectral detection system for common fluorescent and colorimetric assays. This system includes a gradient grating period guided-mode resonance (GGP-GMR) filter and charge-coupled device. In its current form, the GGP-GMR filter, which has a size of less than 2.5 mm, can achieve a spectral detection range of 500–700 nm. Through the direct measurement of the fluorescence emission, the proposed system was demonstrated to detect both the peak wavelength and its corresponding intensity. One fluorescent assay (albumin) and two colorimetric assays (albumin and creatinine) were performed to demonstrate the practical application of the proposed system for quantifying common liquid assays. The results of our system exhibited suitable agreement with those of a commercial spectrometer in terms of the assay sensitivity and limit of detection (LOD). With the proposed system, the fluorescent albumin, colorimetric albumin, and colorimetric creatinine assays achieved LODs of 40.99 and 398 and 25.49 mg/L, respectively. For a wide selection of biomolecules in point-of-care applications, the spectral detection range achieved by the GGP-GMR filter can be further extended and the simple and compact optical path configuration can be integrated with a lab-on-a-chip system.

scholarly journals A Molecularly Imprinted Polymer for Selective Extraction of Phenolic Acids from Human Urine

2021 ◽  
Vol 11 (4) ◽  
pp. 1577
Author(s):  
Marco Mora-Granados ◽  
David González-Gómez ◽  
Jin Su Jeong ◽  
Alejandrina Gallego-Picó
Keyword(s):  
Phenolic Acids ◽  
Molecularly Imprinted Polymer ◽  
Human Urine ◽  
Limit Of Detection ◽  
Ph Dependence ◽  
Selective Extraction ◽  
Screening Methods ◽  
Specific Method ◽  
Imprinted Polymer ◽  
Molecularly Imprinted

Studies for monitoring the bioavailability of dietary flavonoid compounds generate great interest. Among them, low-molecular-weight phenolic acids, secondary metabolites present in colonic catabolism and urinary excretion, have been proposed as biomarkers of polyphenol intake. Using 4-hydroxyphenylacetic acid as a template, a molecularly imprinted polymer (MIP) was synthesized for selective extraction of these hydroxylated metabolites from human urine samples and posterior analysis in an HPLC-DAD-MS system. Polymers were characterized by Scanning electron microscopy (SEM), Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), Brunauer-Emmett-Teller (BET) method, and binding experiments. MIP presents specific recognition ability for template and analogues molecules. This capacity of recognition and the pH dependence of the binding strength was also studied. The method was validated over a concentration range of 0.25–40 mg/L, r2 > 0.995. In the optimized conditions, the recovery value was 94% with RSD 1.2%. The Limit of Detection (LOD) and Limit of Quantification (LOQ) were 1.22 and 3.69 mg/L, respectively. In our knowledge, it is the first time that this methodology is applied to analyze urinary catabolites of the polyphenol compound and to provide a specific method and simple analysis alternative. The selective extraction of these metabolites improves the application and results obtained by other less sensitive analysis methods than the validation method. It also facilitates the development of new screening methods.

scholarly journals Demonstration of a Label-Free and Low-Cost Optical Cavity-Based Biosensor Using Streptavidin and C-Reactive Protein

Biosensors ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 4
Author(s):  
Donggee Rho ◽  
Seunghyun Kim
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Optical Cavity ◽  
Sample Volume ◽  
Small Sample ◽  
Label Free ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Cavity Structure

An optical cavity-based biosensor (OCB) has been developed for point-of-care (POC) applications. This label-free biosensor employs low-cost components and simple fabrication processes to lower the overall cost while achieving high sensitivity using a differential detection method. To experimentally demonstrate its limit of detection (LOD), we conducted biosensing experiments with streptavidin and C-reactive protein (CRP). The optical cavity structure was optimized further for better sensitivity and easier fluid control. We utilized the polymer swelling property to fine-tune the optical cavity width, which significantly improved the success rate to produce measurable samples. Four different concentrations of streptavidin were tested in triplicate, and the LOD of the OCB was determined to be 1.35 nM. The OCB also successfully detected three different concentrations of human CRP using biotinylated CRP antibody. The LOD for CRP detection was 377 pM. All measurements were done using a small sample volume of 15 µL within 30 min. By reducing the sensing area, improving the functionalization and passivation processes, and increasing the sample volume, the LOD of the OCB are estimated to be reduced further to the femto-molar range. Overall, the demonstrated capability of the OCB in the present work shows great potential to be used as a promising POC biosensor.

scholarly journals Ratiometric Fluorescent Biosensors for Glucose and Lactate Using an Oxygen-Sensing Membrane

Biosensors ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 208
Author(s):  
Hong Dinh Duong ◽  
Jong Il Rhee
Keyword(s):  
Limit Of Detection ◽  
Oxygen Sensing ◽  
High Sensitivity ◽  
Glucose Sensing ◽  
Oxidation Reactions ◽  
Lactate Oxidase ◽  
Lactate Oxidation ◽  
Detection Range ◽  
Quenching Effect ◽  
Sensing Membrane

In this study, ratiometric fluorescent glucose and lactate biosensors were developed using a ratiometric fluorescent oxygen-sensing membrane immobilized with glucose oxidase (GOD) or lactate oxidase (LOX). Herein, the ratiometric fluorescent oxygen-sensing membrane was fabricated with the ratio of two emission wavelengths of platinum meso-tetra (pentafluorophenyl) porphyrin (PtP) doped in polystyrene particles and coumarin 6 (C6) captured into silica particles. The operation mechanism of the sensing membranes was based on (i) the fluorescence quenching effect of the PtP dye by oxygen molecules, and (ii) the consumption of oxygen levels in the glucose or lactate oxidation reactions under the catalysis of GOD or LOX. The ratiometric fluorescent glucose-sensing membrane showed high sensitivity to glucose in the range of 0.1–2 mM, with a limit of detection (LOD) of 0.031 mM, whereas the ratiometric fluorescent lactate-sensing membrane showed the linear detection range of 0.1–0.8 mM, with an LOD of 0.06 mM. These sensing membranes also showed good selectivity, fast reversibility, and stability over long-term use. They were applied to detect glucose and lactate in artificial human serum, and they provided reliable measurement results.

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