Chemiluminescence imaging immunoassay for simultaneous determination of TBBPA-DHEE and TBBPA-MHEE in aquatic environments

Development of crosslinker-free antibody-enzyme conjugates for immunoassays in pesticide residue detection

Immunoassays are biochemical analytical techniques based on the specific binding between antigens and antibodies. Due to their high sensitivity, rapid analysis, high throughput, cost-effectiveness, and broad applicability, immunoassays have been widely utilized across various fields. Antibody-enzyme conjugates are essential components for signal generation in immunoassays, with crosslinking chemical (crosslinker)-based methods traditionally employed for their production. However, these methods often involve hazardous reagents and complex procedures, highlighting the need for more eco-friendly alternatives. In this study, we developed a universal, crosslinker-free approach for preparing antibody-enzyme conjugates. This method eliminates the use of chemical reagents such as glutaraldehyde or periodate, as well as the intricate conjugation and purification steps typically required. Instead, gold nanoparticles (AuNPs) were employed as a versatile nanomaterial to passively adsorb horseradish peroxidase (HRP) and antibodies through a simple procedure completed within 60 minutes. The resulting conjugates were characterized using UV-vis spectroscopy, transmission electron microscopy (TEM), and zeta potential analysis. Using acetamiprid (ACE), a widely-used pesticide, as the target model, an enzyme-linked immunosorbent assay (ELISA) was developed based on the AuNP-mediated conjugates. The assay demonstrated performance comparable to that of traditional crosslinker-based methods, with an IC50 of 0.49 ng mL-1 and a limit of detection (LOD) of 0.11 ng mL-1. Recovery rates for ACE in spiked fruit samples were consistent with those obtained using liquid chromatography-mass spectrometry (LC-MS). The proposed method not only provides a reliable alternative for HRP and antibody conjugation but also advances green analytical chemistry by minimizing the use of hazardous chemicals, reducing derivative waste, and improving energy efficiency.

Detection of synovial fluid LTF and S100A8 by chemiluminescence immunoassay for the diagnosis of periprosthetic joint infection

BACKGROUND AND AIMS

Synovial fluid lactoferrin (LTF) and S100 calcium-binding protein A8 (S100A8) have been considered as potential biomarkers for the diagnosis of periprosthetic joint infection (PJI) through our previous research. However, the detection methods of these two proteins are still immature, so a rapid, accurate and cost-effective testing method is warranted.

MATERIALS AND METHODS

We developed chemiluminescent immunoassays (CLIA) for the automated detection of synovial fluid LTF and S100A8 and assessed the analytical performance for these two methods. In addition, we recruited 86 patients who were suspected of PJI after total joint replacement (TJA) and examined their synovial fluid using CLIA to explore the clinical application value of these methods and the diagnostic efficiency of synovial fluid LTF and S100A8 for PJI.

RESULTS

Our established CLIA methods have a wide linear range of 20-10000 ng/mL for LTF detection system and 5-5000 ng/mL for S100A8 detection system. Performance parameters such as precision, specificity, and recovery rate can meet the industry standards. Then, the established methods were used to detect LTF and S100A8 in synovial fluid samples, which showed excellent diagnostic efficiency for PJI, and the areas under ROC curve (AUC) were 0.954 (95% CI: 0.909-0.999) and 0.958 (95% CI: 0.918-0.997), respectively.

CONCLUSION

Our established CLIA methods have the advantages of automation, high throughput, low price, and is expected to be widely popularized in clinical applications. Synovial fluid LTF and S100A8 detected through CLIA had efficient diagnostic potentiality for predicting and diagnosing PJI.

Europium Nanoparticles-Based Fluorescence Immunochromatographic Detection of Three Abused Drugs in Hair

Drug abuse is becoming increasingly dangerous nowadays. Morphine (MOP), methamphetamine (MET) and ketamine (KET) are the most commonly abused drugs. The abuse of these drugs without supervision can cause serious harm to the human body and also endanger public safety. Developing a rapid and accurate method to screen drug suspects and thus control these drugs is essential to public safety. This paper presents a method for the simultaneous quantitative detection of these three drugs in hair by a europium nanoparticles-based fluorescence immunochromatographic assay (EuNPs-FIA). In our study, the test area of the nitrocellulose membrane was composed of three equally spaced detection lines and a quality control line. The test strip realized the quantitative analysis of the samples by detecting the fluorescence brightness of the europium nanoparticles captured on the test line within 15 min. For the triple test strip, the limits of detection of MOP, KET and MET were 0.219, 0.079 and 0.329 ng/mL, respectively. At the same time, it also showed strong specificity. The strip was stable and could be stored at room temperature for up to one year, and the average recovery rate was 85.98-115.92%. In addition, the EuNPs-FIA was validated by high-performance liquid chromatography (HPLC) analysis, and a satisfactory consistency was obtained. Compared to the current immunochromatographic methods used for detecting abused drugs in hair, this method not only increased the number of detection targets, but also ensured sensitivity, improving detection efficiency to a certain extent. The approach can also be used as an alternative to chromatography. It provides a rapid and accurate screening method for the detection of abused drugs in hair and has great application prospects in regard to public safety.

Merging microfluidics with luminescence immunoassays for urgent point-of-care diagnostics of COVID-19

The Coronavirus disease 2019 (COVID-19) outbreak has urged the establishment of a global-wide rapid diagnostic system. Current widely-used tests for COVID-19 include nucleic acid assays, immunoassays, and radiological imaging. Immunoassays play an irreplaceable role in rapidly diagnosing COVID-19 and monitoring the patients for the assessment of their severity, risks of the immune storm, and prediction of treatment outcomes. Despite of the enormous needs for immunoassays, the widespread use of traditional immunoassay platforms is still limited by high cost and low automation, which are currently not suitable for point-of-care tests (POCTs). Microfluidic chips with the features of low consumption, high throughput, and integration, provide the potential to enable immunoassays for POCTs, especially in remote areas. Meanwhile, luminescence detection can be merged with immunoassays on microfluidic platforms for their good performance in quantification, sensitivity, and specificity. This review introduces both homogenous and heterogenous luminescence immunoassays with various microfluidic platforms. We also summarize the strengths and weaknesses of the categorized methods, highlighting their recent typical progress. Additionally, different microfluidic platforms are described for comparison. The latest advances in combining luminescence immunoassays with microfluidic platforms for POCTs of COVID-19 are further explained with antigens, antibodies, and related cytokines. Finally, challenges and future perspectives were discussed.

Indirect competitive-structured electrochemical immunosensor for tetrabromobisphenol A sensing using CTAB-MnO2 nanosheet hybrid as a label for signal amplification

Tetrabromobisphenol A (TBBPA) is a kind of brominated flame retardant that is usually added to products to reduce their flame retardancy. However, its extensive use has resulted in their residues being found in the environment, which is very harmful. Herein, an indirect competitive immunosensor has been established for TBBPA detection based on the signal amplification system. Pd nanospheres in situ reduced on the surface of MnO₂ nanosheet hybrid (MnO₂/Pd) was used as the label for the secondary antibody through the Pd-N bond, and gold-toluidine blue composite was loaded onto MWCNTs (MWCNTs/Au-TB), which functioned as the platform for the immunosensor. The spherical structure of Pd had abundant catalytic active sites, which enhanced the catalytic activity of MnO₂/Pd as the label, hence amplifying the signal response. Besides, MWCNTs/Au-TB improved electron transfer and produced a strong signaling pathway for immobilizing antigens through the Au-NH₂ bond, which can specifically recognize primary antibodies to improve sensitivity. The immunosensor had a linear concentration range of 0-81 ng/mL, a low detection limit of 0.17 ng/mL (S/N = 3), with good stability, selectivity, and reproducibility based on the above advantages. Additionally, the acceptable accuracy and recoveries (recoveries, 92-124%; CV, 3.3-8.8%) in the real water sample analysis indicated that this strategy is promising for emerging pollutant analysis.