scholarly journals A simple AuNPs-based colorimetric aptasensor for chlorpyrifos detection

2021 ◽  
Author(s):  
Yuan Liu ◽  
Taotao Li ◽  
Gaojian Yang ◽  
Yan Deng ◽  
Xianbo Mou ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Tap Water ◽  
Low Cost ◽  
Organophosphorus Pesticide ◽  
Detection Methods ◽  
Label Free ◽  
Human Beings ◽  
Free Gold ◽  
Dissociation Constant Kd ◽  
Colorimetric Aptasensor

Abstract Background Chlorpyrifos (Chl) is an organophosphorus pesticide, which has toxicity to environment, animals and human beings. To overcome the shortages of traditional detection methods of small molecular, this study aimed to develop a sensitive, simple, low cost and on-site rapid method for Chl analysis and detection. Thus, we developed a simple label-free gold nanoparticles (AuNPs) based colorimetric biosensor aptasensor for Chl detection using an aptamer as the caputure probe. Results The Chl-aptamer with low dissociation constant (Kd) of 58.59 ± 6.08 (nM) was selected by ssDNA library immobilized systematic evolution of ligands by enrichment (SELEX). In the absence of Chl, the Chl-aptamer acted as the stabilizer for AuNPs in salt solution. In the presence of Chl, the highly specific Chl-aptamer bound with Chl targets immediately thus a self-aggregation of AuNPs induced by salt was displayed. The fabricated colorimetric aptasensor exhibited an excellent sensitivity for Chl detection with the limit of detection as low as 14.46 nM. In addition, the aptasensor was applied to test Chl in tap water, cucumber and cabbage samples, which showed satisfying results with excellent recovery values between 96.2% and 105.6% and acceptable RSD values below 5%. Conclusions The developed colorimetric aptasensor can serve as a promising candidate for Chl detection in the area of biosensors, which also showed a great potential in simple, cheap and rapid detection of Chl.

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.

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 Graphene Oxide and Fluorescent Aptamer Based Novel Biosensor for Detection of 25-hydroxyvitamin D3

2021 ◽  
Author(s):  
Ritika Gupta ◽  
Sunaina Kaul ◽  
Vishal Singh ◽  
Sandeep Kumar ◽  
Nitin Kumar Singhal
Keyword(s):  
Vitamin D ◽  
Graphene Oxide ◽  
Limit Of Detection ◽  
Low Cost ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Detection Methods ◽  
Hydroxyvitamin D ◽  
25 Hydroxyvitamin D ◽  
Sensitive Sensor

Abstract For maintaining the healthy metabolic status, vitamin D is a beneficial metabolite stored majorly in its pre-activated form, 25-hydroxyvitamin D3 (25(OH)D3). Due to its important role in bone strengthening, the study was planned to quantify 25(OH)D3 levels in our blood. Quantification techniques for 25(OH)D3 are costly thus requiring a need for a low cost, and sensitive detection methods. In this work, an economic, and sensitive sensor for the detection of 25(OH)D3 was developed using aptamer and graphene oxide (GO). Aptamer is an oligonucleotide, sensitive towards its target, whereas, GO with 2D nanosheets provides excellent quenching surface. Aptamer labeled with fluorescein (5’, 6-FAM) is adsorbed by π -π interaction on the GO sheets leading to quenching of the fluorescence due to Förster resonance energy transfer (FRET). However, in the presence of 25(OH)D3, a major portion of aptamer fluorescence remains unaltered, due to its association with 25(OH)D3. However, in the absence, aptamer fluorescence gets fully quenched. Fluorescence intensity quenching was monitored using fluorescence spectrophotometer and agarose gel based system. The limit of detection of 25(OH)D3 by this method was found to be 0.15 µg/mL. Therefore, this method could come up as a new sensing method in the field of vitamin D detection.

scholarly journals A lectin-coupled porous silicon-based biosensor: label-free optical detection of bacteria in a real-time mode

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mona Yaghoubi ◽  
Fereshteh Rahimi ◽  
Babak Negahdari ◽  
Ali Hossein Rezayan ◽  
Azizollah Shafiekhani
Keyword(s):  
Fourier Transform ◽  
Porous Silicon ◽  
Real Time ◽  
Limit Of Detection ◽  
Principal Component ◽  
The Other ◽  
Detection Methods ◽  
Carbohydrate Binding ◽  
Label Free ◽  
E Coli

Abstract Accuracy and speed of detection, along with technical and instrumental simplicity, are indispensable for the bacterial detection methods. Porous silicon (PSi) has unique optical and chemical properties which makes it a good candidate for biosensing applications. On the other hand, lectins have specific carbohydrate-binding properties and are inexpensive compared to popular antibodies. We propose a lectin-conjugated PSi-based biosensor for label-free and real-time detection of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by reflectometric interference Fourier transform spectroscopy (RIFTS). We modified meso-PSiO2 (10–40 nm pore diameter) with three lectins of ConA (Concanavalin A), WGA (Wheat Germ Agglutinin), and UEA (Ulex europaeus agglutinin) with various carbohydrate specificities, as bioreceptor. The results showed that ConA and WGA have the highest binding affinity for E. coli and S. aureus respectively and hence can effectively detect them. This was confirmed by 6.8% and 7.8% decrease in peak amplitude of fast Fourier transform (FFT) spectra (at 105 cells mL−1 concentration). A limit of detection (LOD) of about 103 cells mL−1 and a linear response range of 103 to 105 cells mL−1 were observed for both ConA-E. coli and WGA-S. aureus interaction platforms that are comparable to the other reports in the literature. Dissimilar response patterns among lectins can be attributed to the different bacterial cell wall structures. Further assessments were carried out by applying the biosensor for the detection of Klebsiella aerogenes and Bacillus subtilis bacteria. The overall obtained results reinforced the conjecture that the WGA and ConA have a stronger interaction with Gram-positive and Gram-negative bacteria, respectively. Therefore, it seems that specific lectins can be suggested for bacterial Gram-typing or even serotyping. These observations were confirmed by the principal component analysis (PCA) model.

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.

Paper-Based Analytical Device for Rapid Naked-Eye Detection of Sulfide in Water Samples

2020 ◽  
Vol 42 (5) ◽  
pp. 696-696
Author(s):  
Lingzhi Zhao Lingzhi Zhao
Keyword(s):  
Water Samples ◽  
Limit Of Detection ◽  
Rapid Determination ◽  
Tap Water ◽  
Low Cost ◽  
Color Intensity ◽  
Detection Zone ◽  
Simulated Waste ◽  
Optimized Conditions ◽  
Analytical Device

This paper describes the development of a low-cost paper-based colorimetric analytical device for the accurate and rapid determination of sulfide. Under optimized conditions, Na2S was dropped in the uptake zone I and the probe in the uptake zone II, they converged to the detection zone via capillary force and formed an intense pink resorufin. Sulfide can be quantified based on the average color intensity values of the product “free resorufin”. The color intensity is recorded using a camera phone, and quantification was made using Adobe Photoshop. The as-developed analytical device detected sulfide in the range of 5–400 μM (R2 = 0.982) with the limit of detection (LOD) 1 μM, and was successfully applied in sulfide assay in spiked water samples including tap water and simulated waste water. Colorimetric results from the proposed paper-based colorimetric analytical device were consistent with that from methylene blue (MB) method.

A gold nanoparticle-based label free colorimetric aptasensor for adenosine deaminase detection and inhibition assay

The Analyst ◽  
2015 ◽  
Vol 140 (5) ◽  
pp. 1572-1577 ◽  
Author(s):  
Fen Cheng ◽  
Yue He ◽  
Xiao-Jing Xing ◽  
Dai-Di Tan ◽  
Yi Lin ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Adenosine Deaminase ◽  
Gold Nanoparticle ◽  
Label Free ◽  
Inhibition Assay ◽  
Free Gold ◽  
Novel Strategy ◽  
Colorimetric Aptasensor

A novel strategy for the fabrication of a colorimetric aptasensor using label free gold nanoparticles (AuNPs) is proposed. The aptasensor consists of adenosine (AD) aptamer, AD and AuNPs. The strategy has been employed for the assay of adenosine deaminase (ADA) activity.

scholarly journals Electrochemical Impedance Spectroscopy Characterization of Label-Free Biosensors for the Detection of HER2 in Saliva

Proceedings ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 17
Author(s):  
Imad Abrao Nemeir ◽  
Lynn Mouawad ◽  
Joseph Saab ◽  
Walid Hleihel ◽  
Abdelhamid Errachid ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Low Cost ◽  
Ease Of Use ◽  
Detection Methods ◽  
Cancer Type ◽  
Label Free ◽  
Human Epidermal Receptor

Breast cancer is the leading cancer type for women with two million new yearly infections and more than half a million dead worldwide. Human Epidermal Receptor 2 (HER2) is a prominent breast cancer biomarker that indicates aggressive cancer and is often associated with a bad prognosis and low survival rates. However, current detection methods for HER2 are often time-consuming, expensive, and require a high level of expertise. Biosensors are devices that turn biological interaction into a readable electronic signal; they are known for their high specificity and selectivity for low concentration, as well as their low cost and ease of use, thus making them a better alternative to traditional methods. Also, saliva is becoming a better alternative to blood for the detection of biomarkers due to its non-invasive collection in large quantities with simple collection methods with a richness in disease biomarkers including HER2. Thus, this project aims to develop a label-free, low cost, electrochemical biosensor for the detection of HER2 in saliva. This was done by first depositing diazonium salt onto a screen-printed electrode (SPE) through cyclic voltammetry, then immobilizing anti-HER2 antibodies on the activated SPE using 1-ethyl-3-(3-dimethylamino) propyl carbodiimide/N-hydroxysuccinimide. HER2 biomarker concentrations were detected using electrochemical impedance spectroscopy inside a microfluidic system. The biosensor showed a higher linear detection of HER2 (Y = 0.0062X + 0.1066/R2 = 0.9909) in its physiological concentration range of 5 and 40 pg/mL when compared to other interference proteins: Epidermal Growth Factor Receptor (Y = 0.0016X + 0.0188/R2 = 0.8072) and Human Epidermal Receptor 3 (Y = (0.0035X + 0.0225/R2 = 0.1302). The biosensor was then used to detect 10 pg/mL of HER2 concentration in real saliva using the standard addition methods (Y = 0.0118X + 0.1282/R2 = 0.9876).

scholarly journals Ultra-low HIV-1 p24 detection limits with a bioelectronic sensor

2019 ◽  
Vol 412 (4) ◽  
pp. 811-818 ◽  
Author(s):  
Eleonora Macchia ◽  
Lucia Sarcina ◽  
Rosaria Anna Picca ◽  
Kyriaki Manoli ◽  
Cinzia Di Franco ◽  
...  
Keyword(s):  
Capsid Protein ◽  
Single Molecule ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Wide Field ◽  
Label Free ◽  
Limit Of Quantification ◽  
Great Relevance ◽  
Hiv 1

AbstractEarly diagnosis of the infection caused by human immunodeficiency virus type-1 (HIV-1) is vital to achieve efficient therapeutic treatment and limit the disease spreading when the viremia is at its highest level. To this end, a point-of-care HIV-1 detection carried out with label-free, low-cost, and ultra-sensitive screening technologies would be of great relevance. Herein, a label-free single molecule detection of HIV-1 p24 capsid protein with a large (wide-field) single-molecule transistor (SiMoT) sensor is proposed. The system is based on an electrolyte-gated field-effect transistor whose gate is bio-functionalized with the antibody against the HIV-1 p24 capsid protein. The device exhibits a limit of detection of a single protein and a limit of quantification in the 10 molecule range. This study paves the way for a low-cost technology that can quantify, with single-molecule precision, the transition of a biological organism from being “healthy” to being “diseased” by tracking a target biomarker. This can open to the possibility of performing the earliest possible diagnosis.

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.

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