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 Label-Free Fluorescent DNA Calculator Based on Gold Nanoparticles for Sensitive Detection of ATP

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2494 ◽  
Author(s):  
Jingjing Zhang ◽  
Shizhi Zhang ◽  
Chaoqun Niu ◽  
Chen Liu ◽  
Jie Du ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Deoxyribonucleic Acid ◽  
Logic Gate ◽  
Sensitive Detection ◽  
Label Free ◽  
Detection Range ◽  
Highly Sensitive ◽  
Time Logic ◽  
Fluorescence Dye

Herein we described a deoxyribonucleic acid (DNA) calculator for sensitive detection of the determination of adenosine triphosphate (ATP) using gold nanoparticles (GNP) and PicoGreen fluorescence dye as signal transducer, and ATP and single-stranded DNA (DNA-M′) as activators. The calculator-related performances including linearity, reaction time, logic gate, and selectivity were investigated, respectively. The results revealed that this oligonucleotide sensor was highly sensitive and selective. The detection range was 50–500 nmol/L (R2 = 0.99391) and the detection limit was 46.5 nmol/L. The AND DNA calculator was successfully used for the ATP detection in human urine. Compared with other methods, this DNA calculator has the characteristics of being label-free, non-enzymic, simple, and highly sensitive.

scholarly journals Highly Sensitive Electrochemical Aptasensor for Detecting the VEGF165 Tumor Marker with PANI/CNT Nanocomposites

Biosensors ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 114
Author(s):  
Yunjeong Park ◽  
Min-Sung Hong ◽  
Woo-Hyuk Lee ◽  
Jung-Gu Kim ◽  
Kyunghoon Kim
Keyword(s):  
Tumor Marker ◽  
Limit Of Detection ◽  
Biological Fluid ◽  
Low Cost ◽  
High Sensitivity ◽  
Label Free ◽  
Electrochemical Aptasensor ◽  
Promising Tool ◽  
Highly Sensitive ◽  
Endothelial Growth Factor

Sensing targeted tumor markers with high sensitivity provides vital information for the fast diagnosis and treatment of cancer patients. A vascular endothelial growth factor (VEGF165) have recently emerged as a promising biomarker of tumor cells. The electrochemical aptasensor is a promising tool for detecting VEGF165 because of its advantages such as a low cost and quantitative analysis. To produce a sensitive and stable sensor electrode, nanocomposites based on polyaniline (PANI) and carbon nanotube (CNT) have potential, as they provide for easy fabrication, simple synthesis, have a large surface area, and are suitable in biological environments. Here, a label-free electrochemical aptasensor based on nanocomposites of CNT and PANI was prepared for detecting VEGF165 as a tumor marker. The nanocomposite was assembled with immobilized VEGF165 aptamer as a highly sensitive VEGF165 sensor. It exhibited stable and wide linear detection ranges from 0.5 pg/mL to 1 μg/mL, with a limit of detection of 0.4 pg/mL because of the complementary effect of PANI/CNT. The fabricated aptasensor also exhibited good stability in biological conditions, selectivity, and reproducibility after several measurement times after the dissociation process. Thus, it could be applied for the non-invasive determination of VEGF, in biological fluid diagnosis kits, or in an aptamer-based biosensor platform in the near future.

scholarly journals A label-free logic gate hairpin aptasensor for sensitive detection of ATP based on graphene oxide and PicoGreen dye

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jingjing Zhang ◽  
Handan Xu ◽  
Chunhui Li ◽  
Yilin Wang ◽  
Debing Liu ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Detection Limit ◽  
Adenosine Triphosphate ◽  
Low Cost ◽  
Logic Gate ◽  
High Sensitivity ◽  
Single Strand ◽  
Fluorescence Signal ◽  
Label Free ◽  
Detection Range

Abstract Background In this paper, a simple, enzyme-free, label-free fluorescence, high sensitivity logic gate hairpin aptasensor was developed for adenosine triphosphate (ATP) detection based on graphene oxide (GO) and PicoGreen dye. Methods Using single-strand deoxyribonucleic acid (DNA) and adenosine triphosphate (ATP) as input signal and fluorescence signal as output signal, if single-strand DNA (DNA-L), single-strand DNA (DNA-S), and ATP were present at the same time, one segment of DNA-L formed a hairpin ring with ATP, and the other segment of DNA-L formed a completely complementary hairpin stem with DNA-S. The hairpin DNA was detached from the GO surface, and PicoGreen dye was embedded into the hairpin stem, and the fluorescence signal was enhanced. The molecular logic gate was constructed through the establishment of logic histogram, logic circuit, truth table, and logic formula. The biosensor-related performances including sensitivity, selectivity, and linearity were investigated, respectively. Results We have successfully constructed a AND logic gate. The detection limit of ATP is 138.0 pmol/L (3σ/slope) with detection range of 50–500 nmol/L (R2 = 0.98951), and its sensitivity is 4.748 × 106–6.875 × 108 a.u. (mol/L)−1. Conclusions The logic gate hairpin aptamer sensor has the advantages of high sensitivity, low detection limit, and low cost, and can be successfully applied to the detection of adenosine triphosphate (ATP) in actual human urine samples.

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 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 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.

A Highly Sensitive and Label-Free Microbead-Based ‘Turn-On’ Colorimetric Sensor for the Detection of Mercury(II) in Urine Using a Peroxidase-Like Split G-Quadruplex–Hemin DNAzyme

2018 ◽  
Vol 71 (12) ◽  
pp. 945
Author(s):  
Xin Fu ◽  
He Zhang ◽  
Jie Zhang ◽  
Shi-Tong Wen ◽  
Xing-Cheng Deng
Keyword(s):  
Standard Deviation ◽  
Base Pair ◽  
Limit Of Detection ◽  
Label Free ◽  
Turn On ◽  
Highly Sensitive ◽  
Relative Standard ◽  
G Quadruplex ◽  
Catalytically Active ◽  
Partial Cdna

A highly sensitive and label-free microbead-based ‘turn-on’ assay was developed for the detection of Hg2+ in urine based on the Hg2+-mediated formation of intermolecular split G-quadruplex–hemin DNAzymes. In the presence of Hg2+, T–T mismatches between the two partial cDNA strands were stabilized by a T–Hg2+–T base pair, and can cause the G-rich sequences of the two oligonucleotides to associate to form a split G-quadruplex which is able to bind hemin to form the catalytically active G-quadruplex–hemin DNAzyme. This microbead-based ‘turn-on’ process allows the detection of Hg2+ in urine samples at concentrations as low as 0.5 pM. The relative standard deviation and recovery are 1.2–3.9 and 98.7–103.2%, respectively. The remarkable sensitivity for Hg2+ is mainly attributed to the enhanced mass transport ability that is inherent in homogeneous microbead-based assays. Compared with previous developments of intermolecular split G-quardruplex–hemin DNAzymes for the homogeneous detection of Hg2+ (the limit of detection was 19nM), a signal enhancement of ~1000 times is obtained when such an assay is performed on the surface of microbeads.

scholarly journals D-shaped plastic optical fibre aptasensor for fast thrombin detection in nanomolar range

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Nunzio Cennamo ◽  
Laura Pasquardini ◽  
Francesco Arcadio ◽  
Lia E. Vanzetti ◽  
Alessandra Maria Bossi ◽  
...  
Keyword(s):  
Optical Fibre ◽  
Photoelectron Spectroscopy ◽  
Limit Of Detection ◽  
Low Cost ◽  
Gold Surface ◽  
Coagulation Cascade ◽  
Self Assembled Monolayer ◽  
Detection Range ◽  
Clinical Biomarkers ◽  
Static Contact

AbstractThe development of optical biosensors for the rapid and costless determination of clinical biomarkers is of paramount importance in medicine. Here we report a fast and low-cost biosensor based on a plasmonic D-shaped plastic optical fibre (POF) sensor derivatized with an aptamer specific for the recognition of thrombin, the target marker of blood homeostasis and coagulation cascade. In particular, we designed a functional interface based on a Self Assembled Monolayer (SAM) composed of short Poly Ethylene Glycol (PEG) chains and biotin-modified PEG thiol in ratio 8:2 mol:mol, these latter serving as baits for the binding of the aptamer through streptavidin-chemistry. The SAM was studied by X-ray Photoelectron Spectroscopy (XPS) analysis, static contact angle (CA), Surface Plasmon Resonance (SPR) in POFs, and fluorescence microscopy on gold surface. The optimized SAM composition enabled the immobilization of about 112 ng/cm2 of aptamer. The thrombin detection exploiting POF-Aptasensor occurred in short times (5–10 minutes), the reached Limit of Detection (LOD) was about 1 nM, and the detection range was 1.6–60 nM, indicating the POF-Aptasensor well addresses the needs for a low-cost, simple to use and to realize, rapid, small size and portable diagnostic platform.

scholarly journals Label-free highly sensitive probe detection with novel hierarchical SERS substrates fabricated by nanoindentation and chemical reaction methods

2019 ◽  
Vol 10 ◽  
pp. 2483-2496
Author(s):  
Jingran Zhang ◽  
Tianqi Jia ◽  
Yongda Yan ◽  
Li Wang ◽  
Peng Miao ◽  
...  
Keyword(s):  
Ag Nanoparticles ◽  
Enhancement Factor ◽  
Low Cost ◽  
Hierarchical Structures ◽  
Production Method ◽  
Copper Surface ◽  
Sers Substrate ◽  
Label Free ◽  
Sers Substrates ◽  
Highly Sensitive

Nanostructures have been widely employed in surface-enhanced Raman scattering (SERS) substrates. Recently, in order to obtain a higher enhancement factor at a lower detection limit, hierarchical structures, including nanostructures and nanoparticles, appear to be viable SERS substrate candidates. Here we describe a novel method integrating the nanoindentation process and chemical redox reaction to machine a hierarchical SERS substrate. The micro/nanostructures are first formed on a Cu(110) plane and then Ag nanoparticles are generated on the structured copper surface. The effect of the indentation process parameters and the corrosion time in the AgNO3 solution on the Raman intensities of the SERS substrate with hierarchical structures are experimentally studied. The intensity and distribution of the electric field of single and multiple Ag nanoparticles on the surface of a plane and with multiple micro/nanostructures are studied with COMSOL software. The feasibility of the hierarchical SERS substrate is verified using R6G molecules. Finally, the enhancement factor using malachite green molecules was found to reach 5.089 × 109, which demonstrates that the production method is a simple, reproducible and low-cost method for machining a highly sensitive, hierarchical SERS substrate.

scholarly journals Highly Sensitive and Selective Colorimetric Detection of Methylmercury Based on DNA Functionalized Gold Nanoparticles

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2679 ◽  
Author(s):  
Zheng-Jun Xie ◽  
Xian-Yu Bao ◽  
Chi-Fang Peng
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Limit Of Detection ◽  
Low Cost ◽  
Colorimetric Detection ◽  
Colorimetric Method ◽  
Optimal Conditions ◽  
Surface Deposition ◽  
Highly Sensitive ◽  
Dna Strand

A new colorimetric detection of methylmercury (CH3Hg+) was developed, which was based on the surface deposition of Hg enhancing the catalytic activity of gold nanoparticles (AuNPs). The AuNPs were functionalized with a specific DNA strand (HT7) recognizing CH3Hg+, which was used to capture and separate CH3Hg+ by centrifugation. It was found that the CH3Hg+ reduction resulted in the deposition of Hg onto the surface of AuNPs. As a result, the catalytic activity of the AuNPs toward the chromogenic reaction of 3,3,5,5-tetramethylbenzidine (TMB)-H2O2 was remarkably enhanced. Under optimal conditions, a limit of detection of 5.0 nM was obtained for CH3Hg+ with a linear range of 10–200 nM. We demonstrated that the colorimetric method was fairly simple with a low cost and can be conveniently applied to CH3Hg+ detection in environmental samples.

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