Encapsulation-Stabilized, Europium Containing Nanoparticle as a Probe for Time-Resolved luminescence Detection of Cardiac Troponin I

A highly selective optical sensor Eu-BINAM for assessment of high sensitivity cardiac troponin tumor marker in serum of cancer patients

A novel, easy, touchy and selective spectrofluorimetric technique has been successfully applied for sensitive determination of High Sensitivity Cardiac Troponin (TNHS I) in the serum samples of patients suffering malignant tumors through the usage of optical sensor Eu^3+-BINAM complex. The technique is primarily based on quenching of the Eu³⁺-BINAM complex's luminescence intensity upon introducing various concentrations of High Sensitivity Cardiac Troponin (TNHS I). The synthesis and characterization of the optical sensor was performed via absorption and emission. The sensor was also adapted to offer excitation at 394 nm in acetonitrile at pH 7.5. Concentration of High Sensitivity Cardiac Troponin (TNHS I) in serum samples was found to be proportional to the luminescence intensity quenching of the Eu³⁺-BINAM complex, most prominently at λ_em = 618 nm. The limit of the dynamic range is 4.26 × 10^-4 to 2 ng/mL. The limit of detection and quantitation were calculated to be 1.35 and 4.10 ng/mL, respectively. The suggested analytical approach proved its applicability, simplicity and comparatively interference- free. The technique was effectively recruited to quantify High Sensitivity Cardiac Troponin (TNHS I) in human serum samples. The proposed technique could be further extended to evaluate some biomarkers associated with malignancy related diseases in human.

Microfluidic Paper-Based Device for Medicinal Diagnosis

BACKGROUND

The demand for point-of-care testing (POCT) devices has rapidly grown since they offer immediate test results with ease of use, makingthem suitable for home self-testing patients and caretakers. However, the POCT development has faced the challenges of increased cost and limited resources. Therefore, the paper substrate as a low-cost material has been employed to develop a cost-effective POCT device, known as "Microfluidic paper-based analytical devices (μPADs)". This device is gaining attention as a promising tool for medicinal diagnostic applications owing to its unique features of simple fabrication, low cost, enabling manipulation flow (capillarydriven flow), the ability to store reagents, and accommodating multistep assay requirements.

OBJECTIVE

This review comprehensively examines the fabrication methods and device designs (2D/3D configuration) and their advantages and disadvantages, focusing on updated μPADs applications for motif identification.

METHODS

The evolution of paper-based devices, starting from the traditional devices of dipstick and lateral flow assay (LFA) with μPADs, has been described. Patterned structure fabrication of each technique has been compared among the equipment used, benefits, and drawbacks. Microfluidic device designs, including 2D and 3D configurations, have been introduced as well as their modifications. Various designs of μPADs have been integrated with many powerful detection methods such as colorimetry, electrochemistry, fluorescence, chemiluminescence, electrochemiluminescence, and SER-based sensors for medicinal diagnosis applications.

CONCLUSION

The μPADs potential to deal with commercialization in terms of the state-of-the-art of μPADs in medicinal diagnosis has been discussed. A great prototype, which is currently in a reallife application breakthrough, has been updated.

Dye-sensitized lanthanide containing nanoparticles for luminescence based applications

Due to their exceptional luminescent properties, lanthanide (Ln) complexes represent a unique palette of probes in the spectroscopic toolkit. Their extremely weak brightness due to forbidden Ln electronic transitions can be overcome by indirect dye-sensitization from the antenna effect brought by organic ligands. Despite the improvement brought by the antenna effect, (bio)analytical applications with discrete Ln complexes as luminescent markers still suffers from low sensitivity as they are limited by the complex brightness. Thus, there is a need to develop nano-objects that cumulate the spectroscopic properties of multiple Ln ions. This review firstly gives a brief introduction of the spectral properties of lanthanides both in complexes and in nanoparticles (NPs). Then, the research progress of the design of Ln-doped inorganic NPs with capping antennas, Ln-complex encapsulated NPs and Ln-complex surface functionalized NPs is presented along with a summary of the various photosensitizing ligands and of the spectroscopic properties (excited-state lifetime, brightness, quantum yield). The review also emphasizes the problems and limitations encountered over the years and the solutions provided to address them. Finally, a comparison of the advantages and drawbacks of the three types of NP is provided as well as a conclusion about the remaining challenges both in the design of brighter NPs and in the luminescence based applications.

A Highly Sensitive Time-Gated Fluorescence Immunoassay Platform Using Mn-Doped AgZnInS/ZnS Nanocrystals as Signal Transducers

In this work, a time-gated immunoassay platform using low-energy excitable and fluorescence long-lived Mn:AgZnInS/ZnS nanocrystals as signal transducers was developed and applied to the detection of the capsular polysaccharide (CPS) of Burkholderia pseudomallei, a Gram-negative bacterium that is the causative agent of melioidosis. CPS is a high molecular weight antigen displayed and is shed from the outer membrane of B. pseudomallei. The immunoassay using the time-gated platform presents a limit of detection at around 23 pg/ml when CPS is spiked in human serum.

Time-resolved fluorescence resonance energy transfer-based lateral flow immunoassay using a raspberry-type europium particle and a single membrane for the detection of cardiac troponin I

Herein, we report a novel lateral flow immunoassay (LFIA) system for detecting cardiac troponin I (cTnI) in serum using the time-resolved fluorescence resonance energy transfer (TR-FRET) technique and the fusion 5 membrane. The fusion 5 membrane is used as a strip for LFIA, and it is constructed without additional matrices (such as a sample or conjugation pad). Although this strategy for constructing the LFIA strip is quite simple and cost-effective, LFIA is still not suitable for the analysis of biomarkers that require high sensitivity, such as cTnI. Therefore, the highly sensitive TR-FRET technique is integrated with a fusion 5 membrane-based LFIA strip. To accomplish this, a microparticle covered with europium chelate-contained silica nanoparticles is synthesized as a raspberry-type particle and used as a fluorescence donor. A gold nanorod (GNR) is used as a fluorescence acceptor particle. In the TR-FRET-based LFIA system, the competitive immunoassay should be performed to satisfy the condition required for the FRET phenomenon to occur. Therefore, the fluorescence signal is proportional to the cTnI concentration, ensuring a quantitative analysis of cTnI can be accomplished by measuring the fluorescence signal between the raspberry-type europium particles and GNR. Using the developed TR-FRET-based LFIA system, sensitive detection of cTnI is successfully achieved with a limit of detection of 97 pg/mL in human serum. Moreover, because the result can be obtained using one matrix (the fusion 5 membrane), the developed LFIA system can be employed in cTnI diagnosis with a simple manufacturing process.

A compact time-gated instrument for QDs with low excitation energy and millisecond fluorescence lifetime as signal reporters, and its detection application

Recently, bright quantum dots (QDs) possessing low energy for excitation and long fluorescence lifetime in milliseconds have been reported. These QDs such as Mn doped I(II)-III-VI nanocrystals are promising for highly sensitive time-gated sensing applications with a portable or small benchtop “personal” instrument because their unique optical properties not only ensure a high signal-to-background ratio in time-gated fluorescence-intensity (TGFI) measurement but also significantly simplify the TGFI measurement instrument design criteria. In this work, following up the research progress on these QDs, we developed a compact TGFI measurement instrument with high sensitivity and cost-effectiveness for these QDs (more specifically Mn:AZIS/ZnS QDs) as signal reporters. We applied the instrument for sensitive detection of copper(ii) ions in highly autofluorescent rum (alcoholic beverage) in a fluorescence quenching assay utilizing these QDs for signal transduction. The results from this work suggest that this instrument together with bright QDs with low-energy for excitation and long fluorescence lifetimes should have potential to not only convert many regular (non-time-gated) QD-based fluorescence assays to time-gated assays for higher sensitivities or lower LODs, but also facilitate the development of highly sensitive assays for in-field or point-of-care testing.

Recent Progress in Time-Resolved Biosensing and Bioimaging Based on Lanthanide-Doped Nanoparticles

Luminescent nanomaterials have attracted great attention in luminescence-based bioanalysis due to their abundant optical and tunable surface physicochemical properties. However, luminescent nanomaterials often suffer from serious autofluorescence and light scattering interference when applied to complex biological samples. Time-resolved luminescence methodology can efficiently eliminate autofluorescence and light scattering interference by collecting the luminescence signal of a long-lived probe after the background signals decays completely. Lanthanides have a unique [Xe]4f^N electronic configuration and ladder-like energy states, which endow lanthanide-doped nanoparticles with many desirable optical properties, such as long luminescence lifetimes, large Stokes/anti-Stokes shifts, and sharp emission bands. Due to their long luminescence lifetimes, lanthanide-doped nanoparticles are widely used for high-sensitive biosensing and high-contrast bioimaging via time-resolved luminescence methodology. In this review, recent progress in the development of lanthanide-doped nanoparticles and their application in time-resolved biosensing and bioimaging are summarized. At the end of this review, the current challenges and perspectives of lanthanide-doped nanoparticles for time-resolved bioapplications are discussed.

Point-of-Care Compatibility of Ultra-Sensitive Detection Techniques for the Cardiac Biomarker Troponin I-Challenges and Potential Value

Cardiac biomarkers are frequently measured to provide guidance on the well-being of a patient in relation to cardiac health with many assays having been developed and widely utilised in clinical assessment. Effectively treating and managing cardiovascular disease (CVD) relies on swiftly responding to signs of cardiac symptoms, thus providing a basis for enhanced patient management and an overall better health outcome. Ultra-sensitive cardiac biomarker detection techniques play a pivotal role in improving the diagnostic capacity of an assay and thus enabling a better-informed decision. However, currently, the typical approach taken within healthcare depends on centralised laboratories performing analysis of cardiac biomarkers, thus restricting the roll-out of rapid diagnostics. Point-of-care testing (POCT) involves conducting the diagnostic test in the presence of the patient, with a short turnaround time, requiring small sample volumes without compromising the sensitivity of the assay. This technology is ideal for combatting CVD, thus the formulation of ultra-sensitive assays and the design of biosensors will be critically evaluated, focusing on the feasibility of these techniques for point-of-care (POC) integration. Moreover, there are several key factors, which in combination, contribute to the development of ultra-sensitive techniques, namely the incorporation of nanomaterials for sensitivity enhancement and manipulation of labelling methods. This review will explore the latest developments in cardiac biomarker detection, primarily focusing on the detection of cardiac troponin I (cTnI). Highly sensitive detection of cTnI is of paramount importance regarding the rapid rule-in/rule-out of acute myocardial infarction (AMI). Thus the challenges encountered during cTnI measurements are outlined in detail to assist in demonstrating the drawbacks of current commercial assays and the obstructions to standardisation. Furthermore, the added benefits of introducing multi-biomarker panels are reviewed, several key biomarkers are evaluated and the analytical benefits provided by multimarkers-based methods are highlighted.

Development of a Rapid Automated Fluorescent Lateral Flow Immunoassay to Detect Hepatitis B Surface Antigen (HBsAg), Antibody to HBsAg, and Antibody to Hepatitis C

Background

Accurate, rapid, and cost-effective screening tests for hepatitis B virus (HBV) and hepatitis C virus (HCV) infection may be useful in laboratories that cannot afford automated chemiluminescent immunoassays (CLIAs). We evaluated the diagnostic performance of a novel rapid automated fluorescent lateral flow immunoassay (LFIA).

Methods

A fluorescent LFIA using a small bench-top fluorescence reader, Automated Fluorescent Immunoassay System (AFIAS; Boditech Med Inc., Chuncheon, Korea), was developed for qualitative detection of hepatitis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs), and antibody to HCV (anti-HCV) within 20 minutes. We compared the diagnostic performance of AFIAS with that of automated CLIAs—Elecsys (Roche Diagnostics GmbH, Penzberg, Germany) and ARCHITECT (Abbott Laboratories, Abbott Park, IL, USA)—using 20 seroconversion panels and 3,500 clinical serum samples.

Results

Evaluation with the seroconversion panels demonstrated that AFIAS had adequate sensitivity for HBsAg and anti-HCV detection. From the clinical samples, AFIAS sensitivity and specificity were 99.8% and 99.3% for the HBsAg test, 100.0% and 100.0% for the anti-HBs test, and 98.8% and 99.1% for the anti-HCV test, respectively. Its agreement rates with the Elecsys HBsAg, anti-HBs, and anti-HCV detection assays were 99.4%, 100.0%, and 99.0%, respectively. AFIAS detected all samples with HBsAg genotypes A-F and H and anti-HCV genotypes 1, 1a, 1b, 2a, 2b, 4, and 6. Cross-reactivity with other infections was not observed.

Conclusions

The AFIAS HBsAg, anti-HBs, and anti-HCV tests demonstrated diagnostic performance equivalent to current automated CLIAs. AFIAS could be used for a large-scale HBV or HCV screening in low-resource laboratories or low-to middle-income areas.