Monosaccharide-Mediated Rational Synthesis of a Universal Plasmonic Platform With Broad Spectral Fluorescence Enhancement For High-Sensitivity Cancer Biomarker Analysis

Abstract BackgroundEffective and accurate screening of oncological biomarkers in peripheral blood circulation plays an increasingly vital role in diagnosis and prognosis. High-sensitivity assays can effectively aid clinical decision-making and intervene in cancer in a localized status before they metastasize and become unmanageable. Meanwhile, it is equally pivotal to prevent overdiagnosis of non-life-threatening cancer by eliminating unnecessary treatment and repeated blood draws. Unfortunately, current clinical screening methodologies can hardly simultaneously attain sufficient sensitivity and specificity, especially under resource-restrained circumstances. To circumvent such limitations, particularly for cancer biomarkers from early-onset and recurrence, we aim to develop a universal plasmonic platform for clinical applications, which macroscopically amplifies multiplexed fluorescence signals in a broad spectral window readily adapts to current assay setups without sophisticated accessories or expertise at low cost. MethodsThe plasmonic substrate was chemically synthesized in situ at the solid-liquid interface by rationally screening a panel of reducing monosaccharides and tuning the redox reactions at various catalyst densities and precursor concentrations. The redox properties were studied by Benedict’s assay and electrochemistry. We systemically characterized the morphologies and optical properties of the engineered plasmonic Ag structures by scanning electron microscopy (SEM) and spectroscopy. The structure-fluorescence enhancement correlation was explicitly explained by the finite-difference time-domain (FDTD) simulation and a computational model for gap distribution. Next, we established an enhanced fluoroimmunoassay (eFIA) using a model biomarker for prostate cancer (PCa) and validated it in healthy and PCa cohorts. Prognosis was explored in patients subject to surgical and hormonal interventions following recommended PCa guidelines. ResultsThe monosaccharide-mediated redox reaction yielded a broad category of Ag structures, including sparsely dispersed nanoparticles of various sizes, semi-continuous nanoislands, and crackless continuous films. Optimal broad-spectral fluorescence enhancement from green to far-red was observed for the inhomogeneous, irregularly-shaped semi-continuous Ag nanoisland substrate (AgNIS), synthesized from a well-balanced redox reaction at a stable rate mediated by mannose. In addition, different local electric field intensity distributions in response to various incident excitations were observed at the nanoscale, elucidating the need for irregular and inhomogeneous structures. AgNIS enabled a maximized 54.7-fold macroscopically amplified fluorescence and long-lasting photostability. Point-of-care availability was fulfilled using a customized smartphone prototype with well-paired optics. The eFIA effectively detected the PCa marker in cell lines, xenograft tumors, and patient sera. The plasmonic platform rendered a diagnostic sensitivity of 86.0% and a specificity of 94.7% and capably staged high-grade PCa that the clinical gold standard test failed to stratify. Patient prognosis of surgical and hormonal interventions was non-invasively monitored following efficient medical interventions. The assay time was significantly curtailed on the plasmonic platform upon microwave irradiation. ConclusionsBy investigating the effects of monosaccharides on the seed-mediated chemical synthesis of plasmonic Ag structures, we deduced that potent multiplexed fluorescence enhancement originated from both an adequate reducing power and a steady reduction rate. Furthermore, the inhomogeneous structure with adequate medium gap distances afforded optimal multiwavelength fluorescence enhancement, thus empowering an effective eFIA for PCa. The clinically validated diagnostic and prognostic features, along with the low sample volume, point-of-care feasibility with a smartphone, and microwave-shortened assay time, warrant its potential clinical translation for widespread cancer biomarker analysis.

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Point-of-Care Vertical Flow Allergen Microarray Assay: Proof of Concept

Clinical Chemistry ◽

10.1373/clinchem.2014.223230 ◽

2014 ◽

Vol 60 (9) ◽

pp. 1209-1216 ◽

Cited By ~ 32

Author(s):

Thiruppathiraja Chinnasamy ◽

Loes I Segerink ◽

Mats Nystrand ◽

Jesper Gantelius ◽

Helene Andersson Svahn

Keyword(s):

Point Of Care ◽

Protein Microarray ◽

High Sensitivity ◽

Specific Ige ◽

Protein Microarrays ◽

Vertical Flow ◽

Proof Of Concept ◽

Serum Samples ◽

Clinical Model ◽

Assay Time

Abstract BACKGROUND Sophisticated equipment, lengthy protocols, and skilled operators are required to perform protein microarray-based affinity assays. Consequently, novel tools are needed to bring biomarkers and biomarker panels into clinical use in different settings. Here, we describe a novel paper-based vertical flow microarray (VFM) system with a multiplexing capacity of at least 1480 microspot binding sites, colorimetric readout, high sensitivity, and assay time of <10 min before imaging and data analysis. METHOD Affinity binders were deposited on nitrocellulose membranes by conventional microarray printing. Buffers and reagents were applied vertically by use of a flow controlled syringe pump. As a clinical model system, we analyzed 31 precharacterized human serum samples using the array system with 10 allergen components to detect specific IgE reactivities. We detected bound analytes using gold nanoparticle conjugates with assay time of ≤10 min. Microarray images were captured by a consumer-grade flatbed scanner. RESULTS A sensitivity of 1 ng/mL was demonstrated with the VFM assay with colorimetric readout. The reproducibility (CV) of the system was <14%. The observed concordance with a clinical assay, ImmunoCAP, was R2 = 0.89 (n = 31). CONCLUSIONS In this proof-of-concept study, we demonstrated that the VFM assay, which combines features from protein microarrays and paper-based colorimetric systems, could offer an interesting alternative for future highly multiplexed affinity point-of-care testing.

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Novel High Sensitivity Tuberculosis Point-of-Care Test for People Living with HIV

SSRN Electronic Journal ◽

10.2139/ssrn.3254479 ◽

2018 ◽

Cited By ~ 2

Author(s):

Tobias Broger ◽

Bianca Sossen ◽

Elloise du Toit ◽

Andrew D. Kerkhoff ◽

Charlotte Schutz ◽

...

Keyword(s):

Point Of Care ◽

High Sensitivity ◽

People Living With Hiv ◽

Point Of Care Test ◽

Living With Hiv

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Trends in Diagnosis for Active Tuberculosis Using Nanomaterials

Current Medicinal Chemistry ◽

10.2174/0929867325666180912105617 ◽

2019 ◽

Vol 26 (11) ◽

pp. 1946-1959 ◽

Cited By ~ 3

Author(s):

Le Minh Tu Phan ◽

Lemma Teshome Tufa ◽

Hwa-Jung Kim ◽

Jaebeom Lee ◽

Tae Jung Park

Keyword(s):

Sensitivity And Specificity ◽

High Efficiency ◽

Point Of Care ◽

High Sensitivity ◽

Signs And Symptoms ◽

Diagnostic Methods ◽

Advantages And Disadvantages ◽

Treatment And Prevention ◽

Clinical Tools ◽

Diagnostic Applications

Background:Tuberculosis (TB), one of the leading causes of death worldwide, is difficult to diagnose based only on signs and symptoms. Methods for TB detection are continuously being researched to design novel effective clinical tools for the diagnosis of TB.Objective:This article reviews the methods to diagnose TB at the latent and active stages and to recognize prospective TB diagnostic methods based on nanomaterials.Methods:The current methods for TB diagnosis were reviewed by evaluating their advantages and disadvantages. Furthermore, the trends in TB detection using nanomaterials were discussed regarding their performance capacity for clinical diagnostic applications.Results:Current methods such as microscopy, culture, and tuberculin skin test are still being employed to diagnose TB, however, a highly sensitive point of care tool without false results is still needed. The utilization of nanomaterials to detect the specific TB biomarkers with high sensitivity and specificity can provide a possible strategy to rapidly diagnose TB. Although it is challenging for nanodiagnostic platforms to be assessed in clinical trials, active TB diagnosis using nanomaterials is highly expected to achieve clinical significance for regular application. In addition, aspects and future directions in developing the high-efficiency tools to diagnose active TB using advanced nanomaterials are expounded.Conclusion:This review suggests that nanomaterials have high potential as rapid, costeffective tools to enhance the diagnostic sensitivity and specificity for the accurate diagnosis, treatment, and prevention of TB. Hence, portable nanobiosensors can be alternative effective tests to be exploited globally after clinical trial execution.

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A Rapid, High-Sensitivity SARS-CoV-2 Nucleocapsid Immunoassay to Aid Diagnosis of Acute COVID-19 at the Point of Care: A Clinical Performance Study

Infectious Diseases and Therapy ◽

10.1007/s40121-021-00413-x ◽

2021 ◽

Author(s):

Paul K. Drain ◽

Madhavi Ampajwala ◽

Christopher Chappel ◽

Andre B. Gvozden ◽

Melanie Hoppers ◽

...

Keyword(s):

Clinical Performance ◽

Point Of Care ◽

High Sensitivity ◽

Performance Study

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Evaluation of Production Lots of a Rapid Point-of-Care Lateral Flow Serological Test Intended for Identification of IgM and IgG against the N-Terminal Part of the Spike Protein (S1) of SARS-CoV-2

Viruses ◽

10.3390/v13061043 ◽

2021 ◽

Vol 13 (6) ◽

pp. 1043

Author(s):

Tove Hoffman ◽

Linda Kolstad ◽

Bengt Rönnberg ◽

Åke Lundkvist

Keyword(s):

Predictive Value ◽

Serological Test ◽

Point Of Care ◽

External Validation ◽

High Sensitivity ◽

Lateral Flow ◽

Spike Protein ◽

Individual Level ◽

Lateral Flow Test ◽

Production Errors

The potential of rapid point-of-care (POC) tests has been subject of doubt due to an eventual risk of production errors. The aim was therefore to evaluate the two separate production lots of a commercial POC lateral flow test, intended for the detection of IgM and IgG against the SARS-CoV-2 spike protein (S1). Control samples consisted of serum from individuals with confirmed SARS-CoV-2 infection and pre-COVID-19 negative sera gathered from a biobank. The presence of anti-S1 IgM/IgG in the sera was verified by an in-house Luminex-based serological assay (COVID-19 SIA). One hundred samples were verified as positive for anti-S1 IgG and 74 for anti-S1 IgM. Two hundred samples were verified as negative for anti-S1 IgM/IgG. For the two lots of the POC-test, the sensitivities were 93.2% and 87.8% for IgM and 93.0% and 100% for IgG. The specificities were 100% for IgM and 99.5% for IgG. The positive predictive value was 100% for IgM and 98.9% and 99.0% for IgG. The negative predictive value was 97.6% and 95.7% for IgM, and 96.6% and 100% for IgG. The evaluated POC-test is suitable to assess anti-SARS-CoV-2 S1 IgM and IgG, as a measure of previous virus exposure on an individual level. The external validation of separate lots of rapid POC-tests is encouraged to ensure high sensitivity before market introduction.

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Integrating high-performing electrochemical transducers in lateral flow assay

Analytical and Bioanalytical Chemistry ◽

10.1007/s00216-021-03301-y ◽

2021 ◽

Author(s):

Antonia Perju ◽

Nongnoot Wongkaew

Keyword(s):

High Performance ◽

Point Of Care ◽

Low Cost ◽

High Sensitivity ◽

Lateral Flow ◽

Analytical Performance ◽

Label Free ◽

High Performing ◽

Lateral Flow Assays ◽

Electrochemical Transducers

AbstractLateral flow assays (LFAs) are the best-performing and best-known point-of-care tests worldwide. Over the last decade, they have experienced an increasing interest by researchers towards improving their analytical performance while maintaining their robust assay platform. Commercially, visual and optical detection strategies dominate, but it is especially the research on integrating electrochemical (EC) approaches that may have a chance to significantly improve an LFA’s performance that is needed in order to detect analytes reliably at lower concentrations than currently possible. In fact, EC-LFAs offer advantages in terms of quantitative determination, low-cost, high sensitivity, and even simple, label-free strategies. Here, the various configurations of EC-LFAs published are summarized and critically evaluated. In short, most of them rely on applying conventional transducers, e.g., screen-printed electrode, to ensure reliability of the assay, and additional advances are afforded by the beneficial features of nanomaterials. It is predicted that these will be further implemented in EC-LFAs as high-performance transducers. Considering the low cost of point-of-care devices, it becomes even more important to also identify strategies that efficiently integrate nanomaterials into EC-LFAs in a high-throughput manner while maintaining their favorable analytical performance.

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Ag nanoparticles outperform Au nanoparticles for the use as label in electrochemical point-of-care sensors

Analytical and Bioanalytical Chemistry ◽

10.1007/s00216-021-03288-6 ◽

2021 ◽

Author(s):

Franziska Beck ◽

Carina Horn ◽

Antje J. Baeumner

Keyword(s):

Limit Of Detection ◽

Point Of Care ◽

Automatic Measurement ◽

High Sensitivity ◽

Differential Pulse ◽

Small Sample ◽

Blood Protein ◽

User Friendliness ◽

Response Curves ◽

Assay Protocol

AbstractElectrochemical immunosensors enable rapid analyte quantification in small sample volumes, and have been demonstrated to provide high sensitivity and selectivity, simple miniaturization, and easy sensor production strategies. As a point-of-care (POC) format, user-friendliness is equally important and most often not combinable with high sensitivity. As such, we demonstrate here that a sequence of metal oxidation and reduction, followed by stripping via differential pulse voltammetry (DPV), provides lowest limits of detection within a 2-min automatic measurement. In exchanging gold nanoparticles (AuNPs), which dominate in the development of POC sensors, with silver nanoparticles (AgNPs), not only better sensitivity was obtained, but more importantly, the assay protocol could be simplified to match POC requirements. Specifically, we studied both nanoparticles as reporter labels in a sandwich immunoassay with the blood protein biomarker NT-proBNP. For both kinds of nanoparticles, the dose-response curves easily covered the ng∙mL−1 range. The mean standard deviation of all measurements of 17% (n ≥ 4) and a limit of detection of 26 ng∙mL−1 were achieved using AuNPs, but their detection requires addition of HCl, which is impossible in a POC format. In contrast, since AgNPs are electrochemically less stable, they enabled a simplified assay protocol and provided even lower LODs of 4.0 ng∙mL−1 in buffer and 4.7 ng∙mL−1 in human serum while maintaining the same or even better assay reliability, storage stability, and easy antibody immobilization protocols. Thus, in direct comparison, AgNPs clearly outperform AuNPs in desirable POC electrochemical assays and should gain much more attention in the future development of such biosensors.

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Microfluidics-Based Plasmonic Biosensing System Based on Patterned Plasmonic Nanostructure Arrays

Micromachines ◽

10.3390/mi12070826 ◽

2021 ◽

Vol 12 (7) ◽

pp. 826

Author(s):

Yanting Liu ◽

Xuming Zhang

Keyword(s):

Plasmon Resonance ◽

Point Of Care ◽

Simultaneous Detection ◽

High Sensitivity ◽

Microfluidic Chips ◽

Label Free ◽

Plasmonic Nanostructure ◽

Point Of Care Diagnostics ◽

Surface Enhanced Raman ◽

Nanostructure Arrays

This review aims to summarize the recent advances and progress of plasmonic biosensors based on patterned plasmonic nanostructure arrays that are integrated with microfluidic chips for various biomedical detection applications. The plasmonic biosensors have made rapid progress in miniaturization sensors with greatly enhanced performance through the continuous advances in plasmon resonance techniques such as surface plasmon resonance (SPR) and localized SPR (LSPR)-based refractive index sensing, SPR imaging (SPRi), and surface-enhanced Raman scattering (SERS). Meanwhile, microfluidic integration promotes multiplexing opportunities for the plasmonic biosensors in the simultaneous detection of multiple analytes. Particularly, different types of microfluidic-integrated plasmonic biosensor systems based on versatile patterned plasmonic nanostructured arrays were reviewed comprehensively, including their methods and relevant typical works. The microfluidics-based plasmonic biosensors provide a high-throughput platform for the biochemical molecular analysis with the advantages such as ultra-high sensitivity, label-free, and real time performance; thus, they continue to benefit the existing and emerging applications of biomedical studies, chemical analyses, and point-of-care diagnostics.

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Diagnosis of SARS-Cov-2 Infection by RT-PCR Using Specimens Other Than Naso- and Oropharyngeal Swabs: A Systematic Review and Meta-Analysis

Diagnostics ◽

10.3390/diagnostics11020363 ◽

2021 ◽

Vol 11 (2) ◽

pp. 363

Author(s):

Vânia M. Moreira ◽

Paulo Mascarenhas ◽

Vanessa Machado ◽

João Botelho ◽

José João Mendes ◽

...

Keyword(s):

Systematic Review ◽

Clinical Performance ◽

Point Of Care ◽

Meta Analysis ◽

High Sensitivity ◽

Nasopharyngeal Swab ◽

Sample Collection ◽

Rt Pcr ◽

Oropharyngeal Swab ◽

Nucleic Acid Assays

The rapid and accurate testing of SARS-CoV-2 infection is still crucial to mitigate, and eventually halt, the spread of this disease. Currently, nasopharyngeal swab (NPS) and oropharyngeal swab (OPS) are the recommended standard sampling techniques, yet, these have some limitations such as the complexity of collection. Hence, several other types of specimens that are easier to obtain are being tested as alternatives to nasal/throat swabs in nucleic acid assays for SARS-CoV-2 detection. This study aims to critically appraise and compare the clinical performance of RT-PCR tests using oral saliva, deep-throat saliva/posterior oropharyngeal saliva (DTS/POS), sputum, urine, feces, and tears/conjunctival swab (CS) against standard specimens (NPS, OPS, or a combination of both). In this systematic review and meta-analysis, five databases (PubMed, Scopus, Web of Science, ClinicalTrial.gov and NIPH Clinical Trial) were searched up to the 30th of December, 2020. Case-control and cohort studies on the detection of SARS-CoV-2 were included. The methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS 2). We identified 1560 entries, 33 of which (1.1%) met all required criteria and were included for the quantitative data analysis. Saliva presented the higher accuracy, 92.1% (95% CI: 70.0–98.3), with an estimated sensitivity of 83.9% (95% CI: 77.4–88.8) and specificity of 96.4% (95% CI: 89.5–98.8). DTS/POS samples had an overall accuracy of 79.7% (95% CI: 43.3–95.3), with an estimated sensitivity of 90.1% (95% CI: 83.3–96.9) and specificity of 63.1% (95% CI: 36.8–89.3). The remaining index specimens could not be adequately assessed given the lack of studies available. Our meta-analysis shows that saliva samples from the oral region provide a high sensitivity and specificity; therefore, these appear to be the best candidates for alternative specimens to NPS/OPS in SARS-CoV-2 detection, with suitable protocols for swab-free sample collection to be determined and validated in the future. The distinction between oral and extra-oral salivary samples will be crucial, since DTS/POS samples may induce a higher rate of false positives. Urine, feces, tears/CS and sputum seem unreliable for diagnosis. Saliva testing may increase testing capacity, ultimately promoting the implementation of truly deployable COVID-19 tests, which could either work at the point-of-care (e.g. hospitals, clinics) or at outbreak control spots (e.g., schools, airports, and nursing homes).

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