Colorimetric optical nanosensors for trace explosive detection using metal nanoparticles: advances, pitfalls, and future perspective

2021 ◽  
Author(s):  
Oluwasesan Adegoke ◽  
Niamh Nic Daeid
Keyword(s):  
Metal Nanoparticles ◽  
Colorimetric Assay ◽  
Real Life ◽  
High Sensitivity ◽  
Optical Signal ◽  
Ease Of Use ◽  
Future Perspective ◽  
Explosive Detection ◽  
Explosive Sensor ◽  
Harsh Conditions

Warfare threats and acts of terror are challenging situations encountered by defense agencies across the globe and are of growing concern to the general public, and security-minded policy makers. Detecting ultra-low quantities of explosive compounds in remote locations or under harsh conditions for anti-terror purposes as well as the environmental monitoring of residual or discarded explosives in soil, remains a major challenge. The use of metal nanoparticles (NPs) for trace explosive detection has drawn considerable interest in recent years. For nano-based explosive sensor devices to meet real-life operational demands, analytical parameters such as, long-shelf life, stability under harsh conditions, ease-of-use, high sensitivity, excellent selectivity, and rapid signal response must be met. Generally, the analytical performance of colorimetric-based nanosensor systems is strongly dependent on the surface properties of the nanomaterial used in the colorimetric assay. The size and shape properties of metal NPs, surface functionalisation efficiency, and assay fabrication methods, are factors that influence the efficacy of colorimetric explosive nanosensor systems. This review reports on the design and analytical performances of colorimetric explosive sensor systems using metal NPs as optical signal transducers. The challenges of trace explosive detection, advances in metal NP colorimetric explosive design, limitations of each methods, and possible strategies to mitigate the problems are discussed.

scholarly journals Evaluation of Two Rapid Antigenic Tests for the Detection of SARS-CoV-2 in Nasopharyngeal Swabs

2021 ◽  
Vol 10 (13) ◽  
pp. 2774
Author(s):  
Ysaline Seynaeve ◽  
Justine Heylen ◽  
Corentin Fontaine ◽  
François Maclot ◽  
Cécile Meex ◽  
...  
Keyword(s):  
Real Life ◽  
Rapid Test ◽  
High Sensitivity ◽  
Antigen Detection ◽  
Ease Of Use ◽  
University Hospital ◽  
Performance Criteria ◽  
World Health ◽  
Diagnostic Tools ◽  
The University

(1) Background: In the current context of the COVID-19 crisis, there is a need for fast, easy-to-use, and sensitive diagnostic tools in addition to molecular methods. We have therefore decided to evaluate the performance of newly available antigen detection kits in “real-life” laboratory conditions. (2) Methods: The sensitivity and specificity of two rapid diagnostic tests (RDT)—the COVID-19 Ag Respi-Strip from Coris Bioconcept, Belgium (CoRDT), and the coronavirus antigen rapid test cassette from Healgen Scientific, LLC, USA (HeRDT)—were evaluated on 193 nasopharyngeal samples using RT-PCR as the gold standard. (3) Results: The sensitivity obtained for HeRDT was 88% for all collected samples and 91.1% for samples with Ct ≤ 31. For the CoRDT test, the sensitivity obtained was 62% for all collected samples and 68.9% for samples with Ct ≤ 31. (4) Conclusions: Despite the excellent specificity obtained for both kits, the poor sensitivity of the CoRDT did not allow for its use in the rapid diagnosis of COVID-19. HeRDT satisfied the World Health Organization’s performance criteria for rapid antigen detection tests. Its high sensitivity, quick response, and ease of use allowed for the implementation of HeRDT at the laboratory of the University Hospital of Liège.

Development of an Optical Fiber Sensor with a D-shaped Fiber Bragg Grating Integrated in a Loop-mirror Optical Fiber Laser as a High Sensitivity Refractometer

2021 ◽  
Vol 32 ◽  
Author(s):  
Binh Pham Thanh ◽  
Thuy Van Nguyen ◽  
Van Hoi Pham ◽  
Huy Bui ◽  
Thi Hong Cam Hoang ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Fiber ◽  
Fiber Laser ◽  
Fiber Bragg Grating ◽  
Limit Of Detection ◽  
Optical Fiber Sensor ◽  
High Sensitivity ◽  
Optical Signal ◽  
Bragg Grating ◽  
Loop Mirror

In this paper, we report a new type of refractometer based on a D-shaped fiber Bragg grating (FBG) integrated in a loop-mirror optical fiber laser. This proposed sensor is used in wavelength interrogation method, in which the D-shaped FBG is applied as a refractive index (RI) sensing probe and a mirror to select mode of laser. The D-shaped FBG is prepared by the removal of a portion of the fiber cladding covering the FBG by means of side-polishing technique. The D-shaped FBG sensing probe integrated in a loop-mirror optical fiber laser with saturated pump technique, the characteristics of sensing signals have been improved to obtain stable intensity, narrower bandwidth and higher optical signal-to-noise ratio compare to normal reflection configuration. The limit of detection (LOD) of this sensor can be achieved to 2.95 x 10-4 RIU in the refractive index (RI) range of 1.42-1.44. Accordingly, we believe that the proposed refractometer has a huge potential for applications in biochemical-sensing technique.

The Effect of Lesion Characteristic on Remineralization and Model Sensitivity

1992 ◽  
Vol 71 (3_suppl) ◽  
pp. 811-813 ◽  
Author(s):  
F. Schäfer ◽  
S.J. Raven ◽  
T.A. Parr
Keyword(s):  
Real Life ◽  
High Sensitivity ◽  
Lesion Size ◽  
Experimental Conditions ◽  
Treatment Groups ◽  
Human Enamel ◽  
Enamel Sample ◽  
Two Factors ◽  
Treatment Bias

A major criterion for assessing the value of any experimental model in scientific research is the degree of correspondence between its results and data from the real-life process it is designed to model. Intra-oral models aimed at predicting the anti-caries efficacy of toothpastes or other topical treatments should therefore be calibrated against treatments proven to be effective in a caries clinical trial. For this to be achieved, it is necessary that a model with high sensitivity be designed, while at the same time retaining relevance to the process to be modeled. This means that the effects of the various experimental conditions and parameters of the model on its performance must be understood. The purpose of this paper was to assess the influence of two specific factors on the performance of an in situ enamel remineralization model, which is based on human enamel slabs attached to partial dentures. The two factors are initial lesion severity and origin of enamel sample. The results indicated that initial lesion size affected whether net remineralization or net demineralization occurred during in situ treatment. Samples with an initial range of from 1500 to 2500 (ΔZ) tended more toward demineralization than did samples with ΔZ > 3500. This means that treatment groups must be well-balanced with respect to initial lesion size. Differences in initial demineralization severity between different tooth locations must also be considered so that systematic treatment bias can be avoided. The solution used in the model discussed here is based on a balanced experimental design, which allows this effect to be taken into account in the data analysis.

scholarly journals Evaluation of thin, flexible sensors for time-resolved grip force measurement

2007 ◽  
Vol 221 (12) ◽  
pp. 1687-1699 ◽  
Author(s):  
E R Komi ◽  
J R Roberts ◽  
S J Rothberg
Keyword(s):  
Shear Force ◽  
Grip Force ◽  
Force Measurement ◽  
Real Life ◽  
Force Sensor ◽  
Ease Of Use ◽  
Time Resolved ◽  
Flexible Sensors ◽  
Sensor Performance ◽  
Dynamic Accuracy

Three types of thin, flexible force sensor were studied under a variety of loading conditions to determine their suitability for measuring grip force. Static accuracy, hysteresis, repeatability, and drift errors were established, the effects of shear force and surface curvature were considered, and dynamic accuracy and drift were measured. Novel tests were developed to consider dynamic accuracy and sensitivity to shear loadings. Additionally, three sensors were evaluated in a real-life gripping scenario, measuring grip force during a golf shot. Comments are made on sensor performance, ease of use, and durability.

scholarly journals Colorimetric Detection of Sulfide Anions via Redox-Modulated Surface Chemistry and Morphology of Au-Hg Nanorods

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Xiaotian Zhu ◽  
Chang Liu ◽  
Jie Liu
Keyword(s):  
Surface Chemistry ◽  
Colorimetric Assay ◽  
Colorimetric Detection ◽  
High Sensitivity ◽  
Localized Surface Plasmon ◽  
Wavelength Shift ◽  
Colorimetric Sensing ◽  
Leather Industry ◽  
Colorimetric Response ◽  
Sensitivity And Selectivity

A new colorimetric assay for the detection of sulfide anions with high sensitivity and selectivity is reported, utilizing Au-Hg alloy nanorods (Au-HgNRs) as probe. Au-HgNRs were prepared by modifying gold nanorods (AuNRs) with reducing agent and mercury ions. In an aqueous solution with sulfide anions, the formation of mercuric sulfide due to redox reaction between the amalgams and sulfide anions greatly changed the surface chemistry and morphology of the Au-HgNRs, leading to a red shift of the localized surface plasmon resonance (LSPR) absorption peak, accompanied by a change in colorimetric response. A good linear relationship was obtained between the LSPR peak wavelength shift and concentration of sulfide anion in the range of 1 × 10−5−1 × 10−4 mol/L. The selectivity of this method has been investigated by other anions. The colorimetric sensing system successfully detected sulfide in wastewater from leather industry.

scholarly journals Smart-phone, paper-based fluorescent sensor for ultra-low inorganic phosphate detection in environmental samples

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Mehenur Sarwar ◽  
Jared Leichner ◽  
Ghinwa M. Naja ◽  
Chen-Zhong Li
Keyword(s):  
Inorganic Phosphate ◽  
Fluorescent Sensor ◽  
Detection System ◽  
Rapid Test ◽  
Optical Signal ◽  
Ease Of Use ◽  
Florida Everglades ◽  
Paper Strip ◽  
Phosphate Binding ◽  
Fluorescence Sensing

Abstract A major goal of environmental agencies today is to conduct point-of-collection monitoring of excess inorganic phosphate (Pi) in environmental water samples for tracking aquatic “dead zones” caused by algae blooms. However, there are no existing commercial devices which have been miniaturized and are suitable for the point-of-need-testing (“PONT”) that is required to fully map a large region, such as the Florida Everglades. To solve this challenge, a reflection-mode fluorescence-sensing apparatus was developed, leveraging an environmentally sensitive fluorophore (MDCC) bound to a bacterial phosphate-binding protein to generate a fluorescent optical signal proportional to the concentration of (Pi) present. The combined end-to-end integrated sensor system had a response time of only 4 s, with minimal effects of common interfering agents and a linear range spanning from 1.1 to 64 ppb. To support ease-of-use during PONT, the platform incorporated disposable wax-printed paper strip sample pads and a smartphone camera detection system. Since the EPA threshold is currently 30 ppb to prevent eutrophication, this system serves as a rapid test of whether a region is compliant.

scholarly journals Direct-RT-qPCR Detection of SARS-CoV-2 without RNA Extraction as Part of a COVID-19 Testing Strategy: From Sample to Result in One Hour

Diagnostics ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 605 ◽  
Author(s):  
Eva Kriegova ◽  
Regina Fillerova ◽  
Petr Kvapil
Keyword(s):  
High Throughput Screening ◽  
High Speed ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Rna Extraction ◽  
Rna Isolation ◽  
High Sensitivity ◽  
Ease Of Use ◽  
Diagnostic Tools ◽  
Heat Inactivation

Due to the lack of protective immunity in the general population and the absence of effective antivirals and vaccines, the Coronavirus disease 2019 (COVID-19) pandemic continues in some countries, with local epicentres emerging in others. Due to the great demand for effective COVID-19 testing programmes to control the spread of the disease, we have suggested such a testing programme that includes a rapid RT-qPCR approach without RNA extraction. The Direct-One-Step-RT-qPCR (DIOS-RT-qPCR) assay detects severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in less than one hour while maintaining the high sensitivity and specificity required of diagnostic tools. This optimised protocol allows for the direct use of swab transfer media (14 μL) without the need for RNA extraction, achieving comparable sensitivity to the standard method that requires the time-consuming and costly step of RNA isolation. The limit of detection for DIOS-RT-qPCR was lower than seven copies/reaction, which translates to 550 virus copies/mL of swab. The speed, ease of use and low price of this assay make it suitable for high-throughput screening programmes. The use of fast enzymes allows RT-qPCR to be performed under standard laboratory conditions within one hour, making it a potential point-of-care solution on high-speed cycling instruments. This protocol also implements the heat inactivation of SARS-CoV-2 (75 °C for 10 min), which renders samples non-infectious, enabling testing in BSL-2 facilities. Moreover, we discuss the critical steps involved in developing tests for the rapid detection of COVID-19. Implementing rapid, easy, cost-effective methods can help control the worldwide spread of the COVID-19 infection.

scholarly journals (A210) Chemical Sensor Trial for Nerve Agent Differentiation: Impact of Hydrogen Bonds on Detection

2011 ◽  
Vol 26 (S1) ◽  
pp. s58-s58 ◽  
Author(s):  
A. Oztuna ◽  
H. Nazir
Keyword(s):  
Gas Chromatography ◽  
Hydrogen Bonds ◽  
Chemical Sensor ◽  
High Sensitivity ◽  
Nerve Agents ◽  
Ease Of Use ◽  
Field Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Diethyl Ester ◽  
Promising Alternative

Chemical warfare agents (CWAs) are a growing concern for many countries. The uses of CWAs as they can be synthesized by simple chemical reactions, and often have an extremely high toxicity. Conventional, analytical techniques for the detection of nerve agents from environmental and biological samples include gas chromatography, liquid chromatography, gas chromatography– mass spectrometry, ion chromatography, atomic emission detection, capillary electrophoresis, etc. These methods have very high sensitivity, reliability, and precision. However, in spite of these advantages, these techniques require expensive instrumentation and highly trained personnel. They also are time-consuming and unsuitable for field analysis. To meet these prerequisites of rapid warning and field deployment, more compact, low-cost instruments are highly desirable for facilitating the task of on-site monitoring of nerve agents. a quartz crystal microbalance (QCM) sensors could be a reliable and promising alternative to routine methods because of their simplicity, ease of use and high sensitivity and selectivity.1,2 In this study, we prepared QCM sensors functionalized with –NH2 and –COOH groups for differentiate diethyl ester phosphonic acid (DEHP) from diethyl phthalate (DEP), which are known as G and VX agent stimulants respectively. Infrared spectroscopy (FT-IR) was performed in order to characterize the surface of the sensor after modification and the detection. Furthermore, impact of hydrogen bonds on detection will be discussed.

Recent progress on surface chemistry of plasmonic metal nanoparticles for colorimetric assay of drugs in pharmaceutical and biological samples

2018 ◽  
Vol 105 ◽  
pp. 106-120 ◽  
Author(s):  
Suresh Kumar Kailasa ◽  
Janardhan Reddy Koduru ◽  
Mittal L. Desai ◽  
Tae Jung Park ◽  
Rakesh Kumar Singhal ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Metal Nanoparticles ◽  
Biological Samples ◽  
Recent Progress ◽  
Colorimetric Assay

scholarly journals Towards a hand-held, fast, and sensitive gas chromatograph-ion mobility spectrometer for detecting volatile compounds

2020 ◽  
Author(s):  
André Ahrens ◽  
Stefan Zimmermann
Keyword(s):  
Gas Phase ◽  
Ion Mobility ◽  
Atmospheric Pressure ◽  
Response Times ◽  
Atmospheric Pressure Chemical Ionization ◽  
Real Life ◽  
High Sensitivity ◽  
Resolving Power ◽  
Gas Chromatograph ◽  
Ionization Processes

AbstractIon mobility spectrometers can detect gaseous compounds at atmospheric pressure in the range of parts per trillion within a second. Due to their fast response times, high sensitivity, and limited instrumental effort, they are used in a variety of applications, especially as mobile or hand-held devices. However, most real-life samples are gas mixtures, which can pose a challenge for IMS with atmospheric pressure chemical ionization mainly due to competing gas-phase ionization processes. Therefore, we present a miniaturized drift tube IMS coupled to a compact gas chromatograph for pre-separation, built of seven bundled standard GC columns (Rtx-Volatiles, Restek GmbH) with 250 μm ID and 1.07 m in length. Such pre-separation significantly reduces chemical cross sensitivities caused by competing gas-phase ionization processes and adds orthogonality. Our miniaturized GC-IMS system is characterized with alcohols, halocarbons, and ketones as model substances, reaching detection limits down to 70 pptv with IMS averaging times of just 125 ms. It separates test mixtures of ketones and halocarbons within 180 s and 50 s, respectively. The IMS has a short drift length of 40.6 mm and reaches a high resolving power of RP = 68.

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