Fiber Optic Plasmonic Sandwich Immunosensor: Influence of AuNP Label Size and Concentration
01 Oct 2018-
TL;DR: The effect of size and concentration of the gold nanoparticles (AuNP) labels on the sensitivity of evanescent wave absorbance (EWA) based fiber optic sandwich Immunoglobulin G and goat anti-HIgG immunobiosensor is demonstrated.
Abstract: This study demonstrates the effect of size and concentration of the gold nanoparticles (AuNP) labels on the sensitivity of evanescent wave absorbance (EWA) based fiber optic sandwich immunobiosensor. A plasmonic sandwich immunoassay using human Immunoglobulin G (HIgG) and goat anti-HIgG (GaHIgG) was performed on aU-bent polymethyl methacrylate (PMMA) based plastic optical fiber (POF) probe (core diameter $\pmb{500\ \mu} \mathbf{m}$ and bend diameter 1.4 mm). Enhanced EWA response was observed with 60 nm AuNP labels for the analyte concentration $\pmb{1\ \mu} \mathbf{g}/\mathbf{ml}$ in comparison to 20, 40 and 80 nm AuNP labels. Furthermore, on optimizing the GAbs concentration the sensitivity of the sensor enhanced significantly with $\pmb{20\times 60}$ nm labels with a LOD of 100 fg/ml. The advantages such as ease in fiber probe handling and simple instrumentation are highly promising for development of fiberoptic biosensors for various applications.
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01 Jun 2020
TL;DR: This work proposes to exploit the field-deployable/portable plasmonic fiber-optic absorbance biosensor (P-FAB) platform for one-step, wash-free detection of SARS-CoV-2 virus particles directly in saliva sample with minimal sample pre-processing.
Abstract: Rapid and low-cost diagnosis of COVID-19 is essential to identify the infected subjects, particularly the asymptomatic cases, primarily to arrest the spread of the disease through local transmission Antibody-based chromatographic serological tests, as an alternative to RT-PCR, offer only limited help due to high false positives We propose to exploit our field-deployable/portable plasmonic fiber-optic absorbance biosensor (P-FAB) platform for one-step, wash-free detection of SARS-CoV-2 virus particles directly in saliva sample with minimal sample pre-processing
75 citations
TL;DR: In this article, a dip-type plasmonic fiberoptic absorbance biosensor (P-FAB) capable of zeptomole analyte detection and 6-orders of wide dynamic range is presented.
Abstract: This study demonstrates a rapid, wash-free, dip-type plasmonic fiberoptic absorbance biosensor (P-FAB) capable of zeptomole analyte detection and 6-orders of wide dynamic range. It involves a sandwich immunoassay on a compact U-bent fiber optic probe surface that works by dipping an antibody-functionalized probe into a mixture of sample and gold nanoparticle (AuNP) label suspension. The U-bent fiberoptic probes with a high evanescent wave absorbance sensitivity allow detection of the high extinction AuNP labels measured in terms of light intensity change using a pair of LED and photodetector (PD). This simple and low-cost P-FAB gives an unprecedented detection limit of 0.17 zeptomole for human immunoglobulin G (HIgG) in 25 μL buffer in just 25 min. Further silver enhancement of AuNP labels for 5 min results in a limit of quantitation (LoQ) down to 0.17 zeptomole (∼100−150 molecules in 25 μL), making P-FAB a highly sensitive and low-cost technology for point-of-care diagnostics.
27 citations
TL;DR: A plasmonic fiber optic absorbance biosensor (P-FAB) strategy for mannosylated LAM (Man-LAM or Mtb LAM) detection down to attomolar concentrations demonstrates its potential for an on-site TB diagnosis.
22 citations
TL;DR: A rapid, dip-type, wash-free plasmonic fiber optic absorbance biosensor (P-FAB) strategy for the point-of-care detection of SARS-CoV-2 N-protein, expressed abundantly during the infection is developed.
Abstract: SARS-CoV-2 nucleocapsid protein-based COVID-19 diagnosis is a promising alternative to the high-priced, time-consuming, and labor-intensive RT-PCR tests. Here, we developed a rapid, dip-type, wash-free plasmonic fiber optic absorbance biosensor (P-FAB) strategy for the point-of-care detection of SARS-CoV-2 N-protein, expressed abundantly during the infection. P-FAB involves a sandwich assay with plasmonic labels on the surface of a U-bent fiber optic sensor probe with a high evanescent wave absorbance (EWA) sensitivity. The SARS-CoV-2 N-protein is quantified in terms of the change in the intensity of the light propagating through the U-bent sensor probe coupled to a green LED and a photodetector. Firstly, the optical fiber material (silica vs. polymeric optical fiber), was evaluated to realize a sensitive sensor platform. The optimal size of AuNP labels (20, 40, and 60 nm) to achieve high sensitivity and a lower limit of detection (LoD) was investigated. Following the P-FAB strategy, fused silica/glass optical fiber (GOF) U-bent senor probe and citrate-capped AuNP labels (size ~40 nm) gave rise to an LoD down to ~2.5 ng/mL within 10 mins of read-out time. Further, studies on development and validation of a point of care (PoC) read-out device, and preclinical studies are in progress.
19 citations
TL;DR: In this article , a cholesteric liquid crystal biosensor platform was proposed for one-step, wash-free, rapid detection of the SARS-CoV-2 virus directly with minimal sample pre-processing.
Abstract: Rapid and low-cost diagnosis of coronavirus disease 2019 (COVID-19) is essential to identify infected subjects, particularly asymptomatic cases, primarily to arrest the spread of the disease through local transmission. Antibody-based chromatographic serological tests, as an alternative to the RT-PCR technique, offer only limited help due to high false positives. We propose to exploit our cholesteric liquid crystal biosensor platform for one-step, wash-free, rapid detection of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) virus directly with minimal sample pre-processing. As mentioned above, cholesteric liquid crystals are an effective and innovative approach to healthcare as a rapid test for the diagnosis of COVID-19 and other diseases.
References
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TL;DR: In this paper, the authors describe recent progress in the theory of nanoparticle optical properties, particularly methods for solving Maxwell's equations for light scattering from particles of arbitrary shape in a complex environment.
Abstract: The optical properties of metal nanoparticles have long been of interest in physical chemistry, starting with Faraday's investigations of colloidal gold in the middle 1800s. More recently, new lithographic techniques as well as improvements to classical wet chemistry methods have made it possible to synthesize noble metal nanoparticles with a wide range of sizes, shapes, and dielectric environments. In this feature article, we describe recent progress in the theory of nanoparticle optical properties, particularly methods for solving Maxwell's equations for light scattering from particles of arbitrary shape in a complex environment. Included is a description of the qualitative features of dipole and quadrupole plasmon resonances for spherical particles; a discussion of analytical and numerical methods for calculating extinction and scattering cross-sections, local fields, and other optical properties for nonspherical particles; and a survey of applications to problems of recent interest involving triangula...
9,086 citations
TL;DR: While nanorods with a higher aspect ratio along with a smaller effective radius are the best photoabsorbing nanoparticles, the highest scattering contrast for imaging applications is obtained from nanorod of high aspect ratio with a larger effective radius.
Abstract: The selection of nanoparticles for achieving efficient contrast for biological and cell imaging applications, as well as for photothermal therapeutic applications, is based on the optical properties of the nanoparticles. We use Mie theory and discrete dipole approximation method to calculate absorption and scattering efficiencies and optical resonance wavelengths for three commonly used classes of nanoparticles: gold nanospheres, silica−gold nanoshells, and gold nanorods. The calculated spectra clearly reflect the well-known dependence of nanoparticle optical properties viz. the resonance wavelength, the extinction cross-section, and the ratio of scattering to absorption, on the nanoparticle dimensions. A systematic quantitative study of the various trends is presented. By increasing the size of gold nanospheres from 20 to 80 nm, the magnitude of extinction as well as the relative contribution of scattering to the extinction rapidly increases. Gold nanospheres in the size range commonly employed (∼40 nm)...
4,065 citations
"Fiber Optic Plasmonic Sandwich Immu..." refers background in this paper
...Among various metal nanoparticles, gold nanoparticles (AuNP) have gained great attention due to several advantages such as biocompatibility, facile synthesis and ease in conjugation with biological ligands, antibodies and other moieties [3]....
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TL;DR: The advent of AuNP as a sensory element provided a broad spectrum of innovative approaches for the detection of metal ions, small molecules, proteins, nucleic acids, malignant cells, etc. in a rapid and efficient manner.
Abstract: Detection of chemical and biological agents plays a fundamental role in biomedical, forensic and environmental sciences1–4 as well as in anti bioterrorism applications.5–7 The development of highly sensitive, cost effective, miniature sensors is therefore in high demand which requires advanced technology coupled with fundamental knowledge in chemistry, biology and material sciences.8–13
In general, sensors feature two functional components: a recognition element to provide selective/specific binding with the target analytes and a transducer component for signaling the binding event. An efficient sensor relies heavily on these two essential components for the recognition process in terms of response time, signal to noise (S/N) ratio, selectivity and limits of detection (LOD).14,15 Therefore, designing sensors with higher efficacy depends on the development of novel materials to improve both the recognition and transduction processes. Nanomaterials feature unique physicochemical properties that can be of great utility in creating new recognition and transduction processes for chemical and biological sensors15–27 as well as improving the S/N ratio by miniaturization of the sensor elements.28
Gold nanoparticles (AuNPs) possess distinct physical and chemical attributes that make them excellent scaffolds for the fabrication of novel chemical and biological sensors (Figure 1).29–36 First, AuNPs can be synthesized in a straightforward manner and can be made highly stable. Second, they possess unique optoelectronic properties. Third, they provide high surface-to-volume ratio with excellent biocompatibility using appropriate ligands.30 Fourth, these properties of AuNPs can be readily tuned varying their size, shape and the surrounding chemical environment. For example, the binding event between recognition element and the analyte can alter physicochemical properties of transducer AuNPs, such as plasmon resonance absorption, conductivity, redox behavior, etc. that in turn can generate a detectable response signal. Finally, AuNPs offer a suitable platform for multi-functionalization with a wide range of organic or biological ligands for the selective binding and detection of small molecules and biological targets.30–32,36 Each of these attributes of AuNPs has allowed researchers to develop novel sensing strategies with improved sensitivity, stability and selectivity. In the last decade of research, the advent of AuNP as a sensory element provided us a broad spectrum of innovative approaches for the detection of metal ions, small molecules, proteins, nucleic acids, malignant cells, etc. in a rapid and efficient manner.37
Figure 1
Physical properties of AuNPs and schematic illustration of an AuNP-based detection system.
In this current review, we have highlighted the several synthetic routes and properties of AuNPs that make them excellent probes for different sensing strategies. Furthermore, we will discuss various sensing strategies and major advances in the last two decades of research utilizing AuNPs in the detection of variety of target analytes including metal ions, organic molecules, proteins, nucleic acids, and microorganisms.
3,879 citations
Additional excerpts
...The notable optical property such as high optical extinction of AuNP in the visible region of electromagnetic radiation has led to exploitation of AuNP in realizing immunoassay as in the case of lateral flow assays[4][5][6]....
[...]
TL;DR: In this paper, the authors describe recent progress in the theory of nanoparticle optical properties, particularly methods for solving Maxwell's equations for light scattering from particles of arbitrary shape in a complex environment.
Abstract: The optical properties of metal nanoparticles have long been of interest in physical chemistry, starting with Faraday's investigations of colloidal gold in the middle 1800s. More recently, new lithographic techniques as well as improvements to classical wet chemistry methods have made it possible to synthesize noble metal nanoparticles with a wide range of sizes, shapes, and dielectric environments. In this feature article, we describe recent progress in the theory of nanoparticle optical properties, particularly methods for solving Maxwell's equations for light scattering from particles of arbitrary shape in a complex environment. Included is a description of the qualitative features of dipole and quadrupole plasmon resonances for spherical particles; a discussion of analytical and numerical methods for calculating extinction and scattering cross-sections, local fields, and other optical properties for nonspherical particles; and a survey of applications to problems of recent interest involving triangula...
1,416 citations
"Fiber Optic Plasmonic Sandwich Immu..." refers background in this paper
...The oscillation frequency depends on the density of electron, the effective electron mass and the size and shape of the charge distribution [1]....
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TL;DR: The potentials and limitations of analysis with lateral flow (immuno)assays are illustrated using a literature survey and a SWOT analysis (acronym for “strengths, weaknesses, opportunities, threats”).
Abstract: Lateral flow (immuno)assays are currently used for qualitative, semiquantitative and to some extent quantitative monitoring in resource-poor or non-laboratory environments. Applications include tests on pathogens, drugs, hormones and metabolites in biomedical, phytosanitary, veterinary, feed/food and environmental settings. We describe principles of current formats, applications, limitations and perspectives for quantitative monitoring. We illustrate the potentials and limitations of analysis with lateral flow (immuno)assays using a literature survey and a SWOT analysis (acronym for “strengths, weaknesses, opportunities, threats”). Articles referred to in this survey were searched for on MEDLINE, Scopus and in references of reviewed papers. Search terms included “immunochromatography”, “sol particle immunoassay”, “lateral flow immunoassay” and “dipstick assay”.
1,296 citations
Additional excerpts
...The notable optical property such as high optical extinction of AuNP in the visible region of electromagnetic radiation has led to exploitation of AuNP in realizing immunoassay as in the case of lateral flow assays[4][5][6]....
[...]