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1.
J Nanobiotechnology ; 20(1): 6, 2022 Jan 04.
Article in English | MEDLINE | ID: covidwho-1608546

ABSTRACT

BACKGROUND: Gold nanoparticles (AuNPs) have been widely used in local surface plasmon resonance (LSPR) immunoassays for biomolecule sensing, which is primarily based on two conventional methods: absorption spectra analysis and colorimetry. The low figure of merit (FoM) of the LSPR and high-concentration AuNP requirement restrict their limit of detection (LOD), which is approximately ng to µg mL-1 in antibody detection if there is no other signal or analyte amplification. Improvements in sensitivity have been slow in recent for a long time, and pushing the boundary of the current LOD is a great challenge of current LSPR immunoassays in biosensing. RESULTS: In this work, we developed spectral image contrast-based flow digital nanoplasmon-metry (Flow DiNM) to push the LOD boundary. Comparing the scattering image brightness of AuNPs in two neighboring wavelength bands near the LSPR peak, the peak shift signal is strongly amplified and quickly detected. Introducing digital analysis, the Flow DiNM provides an ultrahigh signal-to-noise ratio and has a lower sample volume requirement. Compared to the conventional analog LSPR immunoassay, Flow DiNM for anti-BSA detection in pure samples has an LOD as low as 1 pg mL-1 within only a 15-min detection time and 500 µL sample volume. Antibody assays against spike proteins of SARS-CoV-2 in artificial saliva that contained various proteins were also conducted to validate the detection of Flow DiNM in complicated samples. Flow DiNM shows significant discrimination in detection with an LOD of 10 pg mL-1 and a broad dynamic detection range of five orders of magnitude. CONCLUSION: Together with the quick readout time and simple operation, this work clearly demonstrated the high sensitivity and selectivity of the developed Flow DiNM in rapid antibody detection. Spectral image contrast and digital analysis further provide a new generation of LSPR immunoassay with AuNPs.


Subject(s)
COVID-19 Serological Testing/methods , COVID-19/diagnosis , SARS-CoV-2/isolation & purification , Surface Plasmon Resonance/methods , Antibodies, Viral/immunology , COVID-19/immunology , COVID-19 Serological Testing/instrumentation , Equipment Design , Gold/chemistry , Humans , Immunoassay/instrumentation , Immunoassay/methods , Metal Nanoparticles/chemistry , SARS-CoV-2/immunology , Saliva/virology , Spike Glycoprotein, Coronavirus/immunology , Surface Plasmon Resonance/instrumentation
2.
Molecules ; 25(20)2020 Oct 13.
Article in English | MEDLINE | ID: covidwho-1305732

ABSTRACT

Nano-islands are entities (droplets or other shapes) that are formed by spontaneous dewetting (agglomeration, in the early literature) of thin and very thin metallic (especially gold) films on a substrate, done by post-deposition heating or by using other sources of energy. In addition to thermally generated nano-islands, more recently, nanoparticle films have also been dewetted, in order to form nano-islands. The localized surface plasmon resonance (LSPR) band of gold nano-islands was found to be sensitive to changes in the surrounding environment, making it a suitable platform for sensing and biosensing applications. In this review, we revisit the development of the concept of nano-island(s), the thermodynamics of dewetting of thin metal films, and the effect of the substrate on the morphology and optical properties of nano-islands. A special emphasis is made on nanoparticle films and their applications to biosensing, with ample examples from the authors' work.


Subject(s)
Gold/chemistry , Nanocomposites/chemistry , Point-of-Care Systems , Surface Plasmon Resonance/instrumentation , Animals , Biosensing Techniques/instrumentation , Growth Hormone/analysis , Humans , Lab-On-A-Chip Devices , Milk/chemistry , Nanotechnology/methods , Surface Plasmon Resonance/methods
3.
Anal Chem ; 93(2): 828-833, 2021 01 19.
Article in English | MEDLINE | ID: covidwho-1065763

ABSTRACT

A variety of surface plasmon resonance (SPR) sensing devices have been extensively used in biochemical detection for their characteristics of label-free, highly sensitive, and faster detecting. Among them, the spectrum-based SPR sensing devices have offered us great advantages in high-throughput sensing due to their large dynamic range and the possibility of detection resolution similar to that offered by angle interrogation. This paper demonstrates a spectrum-based SPR imaging sensing system with fast wavelength scanning capability achieved by an acousto-optic tunable filter (AOTF) and a low-cost and speckle-free halogen lamp implemented as the SPR excitation source. Especially, we developed a novel four-parameter-based spectral curve readjusting (4-PSCR) method for data processing, which offered us a faster and more accurate spectral data curve fitting process than the traditional polynomial fitting method. With the configuration, we have also conducted an SPR high-throughput detection of the novel coronavirus (COVID-19) spike protein, proving its application possibility in the screening of COVID-19 with high accuracy. We believe that the higher sensitivity and accuracy of the system have made it readily used in biochemical imaging and detecting applications.


Subject(s)
Spike Glycoprotein, Coronavirus/analysis , Surface Plasmon Resonance/methods , Algorithms , COVID-19/diagnosis , COVID-19/virology , Humans , Limit of Detection , Optics and Photonics , SARS-CoV-2/isolation & purification , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Surface Plasmon Resonance/instrumentation , Temperature
4.
Anal Chem ; 93(2): 828-833, 2021 01 19.
Article in English | MEDLINE | ID: covidwho-977246

ABSTRACT

A variety of surface plasmon resonance (SPR) sensing devices have been extensively used in biochemical detection for their characteristics of label-free, highly sensitive, and faster detecting. Among them, the spectrum-based SPR sensing devices have offered us great advantages in high-throughput sensing due to their large dynamic range and the possibility of detection resolution similar to that offered by angle interrogation. This paper demonstrates a spectrum-based SPR imaging sensing system with fast wavelength scanning capability achieved by an acousto-optic tunable filter (AOTF) and a low-cost and speckle-free halogen lamp implemented as the SPR excitation source. Especially, we developed a novel four-parameter-based spectral curve readjusting (4-PSCR) method for data processing, which offered us a faster and more accurate spectral data curve fitting process than the traditional polynomial fitting method. With the configuration, we have also conducted an SPR high-throughput detection of the novel coronavirus (COVID-19) spike protein, proving its application possibility in the screening of COVID-19 with high accuracy. We believe that the higher sensitivity and accuracy of the system have made it readily used in biochemical imaging and detecting applications.


Subject(s)
Spike Glycoprotein, Coronavirus/analysis , Surface Plasmon Resonance/methods , Algorithms , COVID-19/diagnosis , COVID-19/virology , Humans , Limit of Detection , Optics and Photonics , SARS-CoV-2/isolation & purification , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Surface Plasmon Resonance/instrumentation , Temperature
5.
Biosens Bioelectron ; 169: 112578, 2020 Dec 01.
Article in English | MEDLINE | ID: covidwho-739775

ABSTRACT

The ongoing global pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to active research in its associated diagnostics and medical treatments. While quantitative reverse transcription polymerase chain reaction (qRT-PCR) is the most reliable method to detect viral genes of SARS-CoV-2, serological tests for specific antiviral antibodies are also important as they identify false negative qRT-PCR responses, track how effectively the patient's immune system is fighting the infection, and are potentially helpful for plasma transfusion therapies. In this work, based on the principle of localized surface plasmon resonance (LSPR), we develop an opto-microfluidic sensing platform with gold nanospikes, fabricated by electrodeposition, to detect the presence and amount of antibodies specific to the SARS-CoV-2 spike protein in 1µL of human plasma diluted in 1mL of buffer solution, within ∼30min. The target antibody concentration can be correlated with the LSPR wavelength peak shift of gold nanospikes caused by the local refractive index change due to the antigen-antibody binding. This label-free microfluidic platform achieves a limit of detection of ∼0.08ng/mL (∼0.5pM), falling under the clinical relevant concentration range. We demonstrate that our opto-microfluidic platform offers a promising point-of-care testing tool to complement standard serological assays and make SARS-CoV-2 quantitative diagnostics easier, cheaper, and faster.


Subject(s)
Antibodies, Viral/blood , Betacoronavirus/immunology , Coronavirus Infections/blood , Nanostructures/chemistry , Pneumonia, Viral/blood , Spike Glycoprotein, Coronavirus/immunology , Surface Plasmon Resonance/instrumentation , Antibodies, Viral/immunology , COVID-19 , Coronavirus Infections/immunology , Coronavirus Infections/virology , Equipment Design , Gold/chemistry , Humans , Lab-On-A-Chip Devices , Limit of Detection , Nanostructures/ultrastructure , Pandemics , Pneumonia, Viral/immunology , Pneumonia, Viral/virology , SARS-CoV-2
6.
ACS Nano ; 14(5): 5268-5277, 2020 May 26.
Article in English | MEDLINE | ID: covidwho-46728

ABSTRACT

The ongoing outbreak of the novel coronavirus disease (COVID-19) has spread globally and poses a threat to public health in more than 200 countries. Reliable laboratory diagnosis of the disease has been one of the foremost priorities for promoting public health interventions. The routinely used reverse transcription polymerase chain reaction (RT-PCR) is currently the reference method for COVID-19 diagnosis. However, it also reported a number of false-positive or -negative cases, especially in the early stages of the novel virus outbreak. In this work, a dual-functional plasmonic biosensor combining the plasmonic photothermal (PPT) effect and localized surface plasmon resonance (LSPR) sensing transduction provides an alternative and promising solution for the clinical COVID-19 diagnosis. The two-dimensional gold nanoislands (AuNIs) functionalized with complementary DNA receptors can perform a sensitive detection of the selected sequences from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) through nucleic acid hybridization. For better sensing performance, the thermoplasmonic heat is generated on the same AuNIs chip when illuminated at their plasmonic resonance frequency. The localized PPT heat is capable to elevate the in situ hybridization temperature and facilitate the accurate discrimination of two similar gene sequences. Our dual-functional LSPR biosensor exhibits a high sensitivity toward the selected SARS-CoV-2 sequences with a lower detection limit down to the concentration of 0.22 pM and allows precise detection of the specific target in a multigene mixture. This study gains insight into the thermoplasmonic enhancement and its applicability in the nucleic acid tests and viral disease diagnosis.


Subject(s)
Betacoronavirus/chemistry , Biosensing Techniques/methods , Surface Plasmon Resonance/methods , Betacoronavirus/genetics , Biosensing Techniques/instrumentation , Biosensing Techniques/standards , DNA, Complementary/chemistry , DNA, Complementary/genetics , Gold/chemistry , Hot Temperature , Metal Nanoparticles/chemistry , Nucleic Acid Hybridization/methods , SARS-CoV-2 , Surface Plasmon Resonance/instrumentation , Surface Plasmon Resonance/standards
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