scholarly journals Highly Selective, Aptamer-Based, Ultrasensitive Nanogold Colorimetric Smartphone Readout for Detection of Cd(II)

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2745 ◽  
Author(s):  
Lu Xu ◽  
Jun Liang ◽  
Yonghui Wang ◽  
Shuyue Ren ◽  
Jin Wu ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Low Cost ◽  
Quantitative Detection ◽  
Practical Application ◽  
Full Agreement ◽  
Experimental Conditions ◽  
Dose Time ◽  
Dimethyl Ammonium ◽  
Rice Samples ◽  
Optimized Conditions

A highly selective and sensitive method for Cd(II) detection was developed based on aptamer and gold nanoparticles (AuNPs) combined with a colorimetric smartphone readout. The experimental conditions such as reaction time of polydiene dimethyl ammonium chloride (PDDA) and AuNPs, PDDA dose, time of aptamer and PDDA incubation, and aptamer concentration were optimized. Under the optimized conditions, the color and red(R) value of the solution was concentration-dependent on Cd(II). The proposed method exhibited a linear range of 1–400 ng/mL (r2 = 0.9794) with a limit of detection (LOD) of 1 ng/mL. This method had been successfully applied to test and quantify Cd(II) in water and rice samples, and the results were in full agreement with those from the atomic absorption spectrometer. Therefore, low-cost colorimetry demonstrated its potential for practical application in visual or quantitative detection with a smartphone. This approach can be readily applied to other analytes.

scholarly journals Dual-Modal Assay Kit for the Qualitative and Quantitative Determination of the Total Water Hardness Using a Permanent Marker Fabricated Microfluidic Paper-Based Analytical Device

Chemosensors ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 97
Author(s):  
Oyejide Damilola Oyewunmi ◽  
Seyed Hamid Safiabadi-Tali ◽  
Sana Jahanshahi-Anbuhi
Keyword(s):  
Ethylenediaminetetraacetic Acid ◽  
Limit Of Detection ◽  
Low Cost ◽  
Water Hardness ◽  
Sample Introduction ◽  
World Health ◽  
Total Hardness ◽  
Quantitative Detection ◽  
Qualitative And Quantitative ◽  
Analytical Device

A dip-and-read microfluidic paper-based analytical device (µPAD) was developed for the qualitative and quantitative detection of the total hardness of water. To create well-defined hydrophobic barriers on filter paper, a regular office printer and a commercially available permanent marker pen were utilized as a quick and simple technique with easily accessible equipment/materials to fabricate µPAD in new or resource-limited laboratories without sophisticated equipment. After a wettability and barrier efficiency analysis on the permanent marker colors, the blue and green ink markers exhibited favorable hydrophobic properties and were utilized in the fabrication of the developed test devices. The device had five reaction and detection zones modeled after the classification given by the World Health Organization (WHO), so qualitatively it determined whether the water was ‘soft’, ‘moderately hard’, ‘hard’, or ‘very hard’ by changing color from blue to pink in about 3 min. The device was also used to introduce an alternative colorimetric reaction for quantitative analysis of the water hardness without the need for ethylenediaminetetraacetic acid (EDTA) and without compromising the simplicity and low cost of the device. The developed µPAD showed a calculated limit of detection (LOD) of 0.02 mM, which is at least 80% less than those of commercially available test strips and other reported µPADs, and the results of the real-world samples were consistent with those of the standard titration (with EDTA). In addition, the device exhibited stability for 2 months at room and frigid condition (4 °C) and at varying harsh temperatures from 25 to 100 °C. The results demonstrate that the developed paper-based device can be used for rapid, on-site analysis of water with no interferences and no need for a pipette for sample introduction during testing.

scholarly journals Disposable silicon-based all-in-one micro-qPCR for rapid on-site detection of pathogens

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Estefania Nunez-Bajo ◽  
Alexander Silva Pinto Collins ◽  
Michael Kasimatis ◽  
Yasin Cotur ◽  
Tarek Asfour ◽  
...  
Keyword(s):  
Real Time ◽  
Limit Of Detection ◽  
Low Cost ◽  
High Specificity ◽  
Rapid Screening ◽  
Quantitative Detection ◽  
The Novel ◽  
Novel Coronavirus ◽  
Silicon Based ◽  
Specific Sequences

AbstractRapid screening and low-cost diagnosis play a crucial role in choosing the correct course of intervention when dealing with highly infectious pathogens. This is especially important if the disease-causing agent has no effective treatment, such as the novel coronavirus SARS-CoV-2, and shows no or similar symptoms to other common infections. Here, we report a disposable silicon-based integrated Point-of-Need transducer (TriSilix) for real-time quantitative detection of pathogen-specific sequences of nucleic acids. TriSilix can be produced at wafer-scale in a standard laboratory (37 chips of 10 × 10 × 0.65 mm in size can be produced in 7 h, costing ~0.35 USD per device). We are able to quantitatively detect a 563 bp fragment of genomic DNA of Mycobacterium avium subspecies paratuberculosis through real-time PCR with a limit-of-detection of 20 fg, equivalent to a single bacterium, at the 35th cycle. Using TriSilix, we also detect the cDNA from SARS-CoV-2 (1 pg) with high specificity against SARS-CoV (2003).

scholarly journals Surface-modified Colloid CdTe/CdS Quantum Dots by a Biocompatible Thiazolidine Derivative as Promising Platform for Immobilization of Glucose Oxidase: Application to Fluorescence Sensing of Glucose

2021 ◽  
Author(s):  
Rahman Hallaj ◽  
Zahra Hosseinchi
Keyword(s):  
Quantum Dots ◽  
Glucose Oxidase ◽  
Limit Of Detection ◽  
Low Cost ◽  
Fluorescence Emission ◽  
Cds Quantum Dots ◽  
Fluorescence Sensing ◽  
Experimental Conditions ◽  
Glucose Determination ◽  
Cds Qds

Abstract This work focuses on the synthesis of novel modified core-shell CdTe/CdS quantum dots (QDs) and develops as a fluorescence sensor for glucose determination. The (E)-2,2'-(4,4'-dioxo-2,2'-dithioxo-2H,2'H-[5,5'-bithiazolylidene]-3,3'(4H,4'H)-diyl)bis(3- mercaptopropanoic acid) (DTM) as a new derivative of thiazolidine was synthesized and characterized and used to surface-modification of CdTe/CdS QDs. DTM-capped CdTe/CdS QDs used to immobilization of glucose oxidase (GOD). The intensity fluorescence emission of the CdSe/CdS-DTM/GOD is highly sensitive to the concentration of H2O2 as a byproduct of the catalytic oxidation of glucose. The experimental results showed that the quenched fluorescence was proportional to the glucose concentration within the range of 10 nM − 0.32 µM under optimized experimental conditions. The limit of detection of this system was found to be 4.3 nM. Compared with most of the existing methods, this newly developed system possesses many advantages, including simplicity, low cost, and good sensitivity.

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.

scholarly journals Facile and Low-Cost SPE Modification Towards Ultra-Sensitive Organophosphorus and Carbamate Pesticide Detection in Olive Oil

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 4988
Author(s):  
Dionysios Soulis ◽  
Marianna Trigazi ◽  
George Tsekenis ◽  
Chrysoula Chandrinou ◽  
Apostolos Klinakis ◽  
...  
Keyword(s):  
Olive Oil ◽  
Limit Of Detection ◽  
Organophosphorus Pesticides ◽  
Low Cost ◽  
Linear Range ◽  
The Family ◽  
Forward Transfer ◽  
Optimized Conditions ◽  
Carbamate Pesticide

Despite the fact that a considerable amount of effort has been invested in the development of biosensors for the detection of pesticides, there is still a lack of a simple and low-cost platform that can reliably and sensitively detect their presence in real samples. Herein, an enzyme-based biosensor for the determination of both carbamate and organophosphorus pesticides is presented that is based on acetylcholinesterase (AChE) immobilized on commercially available screen-printed carbon electrodes (SPEs) modified with carbon black (CB), as a means to enhance their conductivity. Most interestingly, two different methodologies to deposit the enzyme onto the sensor surfaces were followed; strikingly different results were obtained depending on the family of pesticides under investigation. Furthermore, and towards the uniform application of the functionalization layer onto the SPEs’ surfaces, the laser induced forward transfer (LIFT) technique was employed in conjunction with CB functionalization, which allowed a considerable improvement of the sensor’s performance. Under the optimized conditions, the fabricated sensors can effectively detect carbofuran in a linear range from 1.1 × 10−9 to 2.3 × 10−8 mol/L, with a limit of detection equal to 0.6 × 10−9 mol/L and chlorpyrifos in a linear range from 0.7 × 10−9 up to 1.4 × 10−8 mol/L and a limit of detection 0.4 × 10−9 mol/L in buffer. The developed biosensor was also interrogated with olive oil samples, and was able to detect both pesticides at concentrations below 10 ppb, which is the maximum residue limit permitted by the European Food Safety Authority.

scholarly journals Optimized qRT-PCR Approach for the Detection of Intra- and Extra-Cellular SARS-CoV-2 RNAs

2020 ◽  
Vol 21 (12) ◽  
pp. 4396 ◽  
Author(s):  
Tuna Toptan ◽  
Sebastian Hoehl ◽  
Sandra Westhaus ◽  
Denisa Bojkova ◽  
Annemarie Berger ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Low Cost ◽  
World Health ◽  
Quantitative Detection ◽  
Rt Pcr ◽  
M Gene ◽  
Control And Prevention ◽  
Pcr Assays ◽  
Novel Coronavirus ◽  
Health Organization

The novel coronavirus SARS-CoV-2 is the causative agent of the acute respiratory disease COVID-19, which has become a global concern due to its rapid spread. Meanwhile, increased demand for testing has led to a shortage of reagents and supplies and compromised the performance of diagnostic laboratories in many countries. Both the World Health Organization (WHO) and the Center for Disease Control and Prevention (CDC) recommend multi-step RT-PCR assays using multiple primer and probe pairs, which might complicate the interpretation of the test results, especially for borderline cases. In this study, we describe an alternative RT-PCR approach for the detection of SARS-CoV-2 RNA that can be used for the probe-based detection of clinical isolates in diagnostics as well as in research labs using a low-cost SYBR green method. For the evaluation, we used samples from patients with confirmed SARS-CoV-2 infections and performed RT-PCR assays along with successive dilutions of RNA standards to determine the limit of detection. We identified an M-gene binding primer and probe pair highly suitable for the quantitative detection of SARS-CoV-2 RNA for diagnostic and research purposes.

scholarly journals ANALYTICAL CHARACTERISTICS OF FLUORESCENT SUSPENSION NANOCRYSTAL-ENCODED MICROARRAY ADAPTED FOR SIMULTANEOUS QUANTITATIVE DETECTION OF FREE AND TOTAL PSA IN SERUM SAMPLES

2015 ◽  
Vol 14 (4) ◽  
pp. 31-38
Author(s):  
K. I. Brazhnik ◽  
Z. A. Sokolova ◽  
M. A. Baryshnikova ◽  
R. S. Bilan ◽  
I. R. Nabiev ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Low Cost ◽  
Specific Antigen ◽  
Simultaneous Detection ◽  
Diagnostic System ◽  
Serum Markers ◽  
Quantitative Detection ◽  
Clinical Approach ◽  
Serum Samples ◽  
Total Psa

Multiplexed suspension systems of anew generation are capable to provide precise quantitative profiling of mul- tipledisease-specific markers in human body fluids. We have developed suspension microarrays based on microbeads encoded with fluorescent nanociystals, that show undeniable advantages overavailable analogues in terms of improved multiplexing capabilities, physical and optical properties, low cost and simplicity of analysisperformance. We have adapted QD-encoded suspension microarrays for the simultaneous detection of two forms of prostate-specific antigen (PSA) in human serum by means of classical flow cytometiy. In the present study, we describe in detail the designed system properties including evaluation the microarray for quantitative analysis of serum markers in comparison to standard clinical approach ELISA, as well asestimation of the most important analytical characteristics, such as analytic sensitivity (limit of detection), reproducibility, reliability and accuracy of the analysis, the linear rangesfor detectable- marker concentrations. Experimental data suggested that the developed diagnostic system quantifies two forms of PSA in blood serum samples of patients with high accuracy, precision and reliability.

scholarly journals Optimized qRT-PCR approach for the detection of intra- and extra-cellular SARS-CoV-2 RNAs

2020 ◽  
Author(s):  
Tuna Toptan ◽  
Sebastian Hoehl ◽  
Sandra Westhaus ◽  
Denisa Bojkova ◽  
Annemarie Berger ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Low Cost ◽  
World Health ◽  
Quantitative Detection ◽  
Rt Pcr ◽  
M Gene ◽  
Control And Prevention ◽  
Pcr Assays ◽  
Novel Coronavirus ◽  
Health Organization

AbstractThe novel coronavirus SARS-CoV-2 is the causative agent of the acute respiratory disease COVID-19 which has become a global concern due to its rapid spread. Meanwhile, increased demand in testing has led to shortage of reagents, supplies, and compromised the performance of diagnostic laboratories in many countries. Both the world health organization (WHO) and the Center for Disease Control and Prevention (CDC) recommend multi-step RT-PCR assays using multiple primer and probe pairs, which might complicate interpretation of the test results especially for borderline cases. In this study, we describe an alternative RT-PCR approach for the detection of SARS-CoV-2 RNA that can be used for the probe-based detection of clinical isolates in the diagnostics as well as in research labs using a low cost SYBR green method. For the evaluation, we used samples from patients with confirmed SARS-CoV-2 infection and performed RT-PCR assays along with successive dilutions of RNA standards to determine the limit of detection. We identified an M-gene binding primer and probe pair highly suitable for quantitative detection of SARS-CoV-2 RNA for diagnostic and research purposes.

scholarly journals Sensitive Colorimetric Detection of Interleukin-6 via Lateral Flow Assay Incorporated Silver Amplification Method

2021 ◽  
Vol 9 ◽  
Author(s):  
Mohammad Rahbar ◽  
Yuling Wu ◽  
J. Anand Subramony ◽  
Guozhen Liu
Keyword(s):  
Interleukin 6 ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Colorimetric Detection ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Quantitative Detection ◽  
Amplification Method ◽  
Silver Amplification

Interleukin-6 (IL-6) is a pro/anti-inflammatory cytokine, the quantitative detection of which has been extensively considered for diagnosis of inflammatory associated diseases. However, there has not yet been a reliable, low-cost, and user-friendly platform developed for point-of-care (POC) detection of IL-6, which will eliminate the conventional costly, time-consuming, and complex assays. In this work, we developed a lateral flow assay for colorimetric detection of IL-6, using anti-IL-6 antibodies conjugated to gold nanoparticles (AuNPs) as the detection probes. Silver amplification technique was incorporated with the newly developed assay in order to enhance the obtained colorimetric signals, allowing sensitive detection of IL-6 in human serum in the desired physiological ranges (i.e., 5–1000 pg/mL). A limit of detection of 5 pg/mL could be achieved for IL-6 detection in serum with the amplification step which was not achievable in the standard assay. The corresponding specificity and reproducibility tests were all preformed to confirm the reliability of this assay for quantitative measurement of IL-6 in a POC manner.

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.

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