Accurate detection of β-hCG in women's serum and cervical secretions for predicting early pregnancy viability based on time-resolved luminescent lanthanide nanoprobes

Sensitive and specific detection of β-hCG in women's serum and cervical secretions is of great significance for early pregnancy evaluation. However, the accurate detection of trace amounts of β-hCG in cervical secretions remains challenging because of its low level. Herein, we report a unique strategy for β-hCG detection in a heterogeneous sandwich-type bioassay by using LiLuF₄:Ce,Tb nanoparticles as time-resolved photoluminescence (PL) nanoprobes. By taking advantage of the intense and long-lived PL of the nanoprobes, the short-lived background autofluorescence can be completely eliminated, which enables the sensitive detection of β-hCG with a linear range of 0-10 ng mL^-1 and a detection limit down to 6.1 pg mL^-1, approximately two orders of magnitude improvement relative to that of a commercial β-hCG assay kit. Furthermore, we demonstrate the application of the nanoprobes for accurate detection of β-hCG in clinical serum and cervical secretion samples and unveil that the ratio of β-hCG levels in cervical secretions and serum can be a good indicator of early pregnancy viability in unknown locations. These findings bring new opportunities in perinatal medicine by employing luminescent lanthanide nanoprobes, thus laying a foundation for future development of luminescent nanoprobes for versatile biomedical applications.

Engineering of CdTe/SiO2 nanocomposites: Enhanced signal amplification and biocompatibility for electrochemiluminescent immunoassay of alpha-fetoprotein

Electrochemiluminescent (ECL) performance and cytotoxicity of CdTe quantum dots (QDs)-based nanocomposites and its possible application for ECL immunoassay were investigated. Two types of CdTe-based nanocomposites, i.e., SiO₂-coated CdTe (CdTe@SiO₂) and CdTe-functionalized SiO₂ (SiO₂@CdTe), were synthesized and comprehensively compared in regarding of the cytotoxicity and ECL performance. The in vitro cytotoxicity of SiO₂@CdTe and CdTe@SiO₂ nanoparticles was assessed in L02 cells using standard CCK-8 assay, and their ECL performance was investigated by constructing sandwiched immunosensor using SiO₂@CdTe and CdTe@SiO₂ as tags for the labelled antibody, respectively. The results showed that CdTe@SiO₂ exhibited much lower cytotoxicity and a higher ECL intensity than SiO₂@CdTe. Taking the analysis of alpha-fetoprotein (AFP) as an example, the ECL immunosensor using CdTe@SiO₂ as an emitter was proved to have a wide linear dynamic range from 1.0 pg mL^-1 to 100 ng mL^-1 with a low detection limit of 0.22 pg mL^-1 (S/N ratio of 3). The ECL immunosensor also demonstrated satisfactory recovery and excellent reproducibility and stability, indicating that this method has prospects in practical application in the clinical diagnosis of AFP.

Integration of patterned photonic nitrocellulose and microfluidic chip for fluorescent point-of-care testing of multiple targets

With the unique capability of enhancing fluorescence, photonic material is integrated into microfluidic chip for point-of-care testing of multiple targets.

Simple and rapid monitoring of doxorubicin using streptavidin-modified microparticle-based time-resolved fluorescence immunoassay

Developing a simple analytical method suitable for therapeutic drug monitoring in a clinical setting is key to establishing guidelines on accurate dose administration and the advancement of precision medicine. We devised a simple rapid analytical method through the combination of streptavidin-modified microparticles and a time-resolved fluorescence immunoassay for therapeutic drug monitoring. The analytical performance of this method was investigated and validated using clinical samples. By determination of doxorubicin concentration, the proposed assay has shown a satisfactory linear range of detection (3.8-3000 ng mL-1) with a limit of detection of 3.8 ng mL-1 and an IC50 of 903.9 ng mL-1. The intra and inter-assay coefficients of variation were 4.12-5.72% and 5.48-6.91%, respectively, and the recovery was acceptable. The applicability of the proposed assay was assessed by comparing the determined results with those measured by LC-MS/MS, presenting a satisfactory correlation (R 2 = 0.9868). The proposed assay, which shows satisfactory analytical performance, has great potential for application in the field of TDM in the future.

Advances in human chorionic gonadotropin detection technologies: a review

Human chorionic gonadotropin (HCG) is a glycoprotein secreted by placental trophoblast cells in pregnancy. HCG is a heterodimer composed of two different α- and β-subunits, with the latter being unique to HCG. As well as being the most important diagnostic markers for pregnancy, HCG is also a tumor marker, therefore, quantitative detection of HCG is of great value. Numerous advanced technologies have been developed for HCG concentration detection including electrochemical immunoassay, chemiluminescent immunoassay, fluorescence immunoassay, resonance scattering spectrometry, atomic emission spectrometry, radioimmunoassay, MS and so on. Some have pursued simple and easy operation, while others have emphasized on accuracy and applications in clinical medicine. This review provides a comprehensive summary of various methods of detecting HCG.

A Dual-Color Quantum Dots Encoded Frit-Based Immunoassay for Visual Detection of Aflatoxin M1 and Pirlimycin Residues in Milk

Mycotoxins and antibacterial agents are the main chemical hazards that lead to several health problems. Nowadays, multiplex immunoassay is a primary goal throughout the world. Here, aflatoxin M₁ and pirlimycin were selected as models, and a novel dual colorimetric encoded frit-based immunoassay was developed for simultaneously screening of aflatoxin M₁ and pirlimycin residues in milk. This multiplex frit-based immunoassay combined two monoclonal antibodies to extend the spectrum of analytes and to enable detection of two classes of analytes in a single test. The cutoff values were 0.02 μg/kg for aflatoxin M₁ and 0.5 μg/kg for pirlimycin, which satisfied the requirement to measure the maximum residue levels. The novel colorimetric frit-based immunoassay has the advantage of high throughput, short analysis time, reduced overall cost per assay, and can be used as a rapid screening technique for simultaneously detecting aflatoxin M₁ and pirlimycin residues in milk.

Highly Stable Lyophilized Homogeneous Bead-Based Immunoassays for On-Site Detection of Bio Warfare Agents from Complex Matrices

This study shows the development of dry, highly stable immunoassays for the detection of bio warfare agents in complex matrices. Thermal stability was achieved by the lyophilization of the complete, homogeneous, bead-based immunoassay in a special stabilizing buffer, resulting in a ready-to-use, simple assay, which exhibited long shelf and high-temperature endurance (up to 1 week at 100 °C). The developed methodology was successfully implemented for the preservation of time-resolved fluorescence, Alexa-fluorophores, and horse radish peroxidase-based bead assays, enabling multiplexed detection. The multiplexed assay was successfully implemented for the detection of Bacillus anthracis, botulinum B, and tularemia in complex matrices.

A sensitive electrochemical immunosensor for the detection of human chorionic gonadotropin based on a hierarchical nanoporous AuAg alloy

A sensitive immunosensor for hCG detection is designed based on assembling the antibody on graphene sheets and ionic liquid composite film. The HNP-AuAg alloy is used as hCG antibody carrier for the preparation of a highly sensitive immunosensor.

Simultaneous fluoroimmunoassay of two tumor markers based on CdTe quantum dots and gold nanocluster coated-silica nanospheres as labels

Fluoroimmunoassay for simultaneous detection of CEA and AFP.

Label-free and highly sensitive electrochemiluminescence biosensing using quantum dots/carbon nanotubes in ionic liquid

A universal and label-free electrochemiluminescence biosensing platform with high sensitivity was developed based on quantum dots/carbon nanotubes in ionic liquid.

A graphene oxide and exonuclease-aided amplification immuno-sensor for antigen detection

We have developed a novel immuno-sensor applied to protein detection based on exonuclease III (Exo III)-induced signal amplification, multiplex binding of the biotin-streptavidin system and the fluorescence quenching ability of graphene oxide.

Sensitive sandwich electrochemical immunosensor for human chorionic gonadotropin using nanoporous Pd as a label

GNPs/PB/GNPs and NP-Pd were prepared to immobilize Ab₁ and HRP–Ab₂ respectively and combined to construct a sandwich-type immunosensor for hCG.

A novel signal amplification strategy of an electrochemical immunosensor for human chorionic gonadotropin, based on nanocomposites of multi-walled carbon nanotubes–ionic liquid and nanoporous Pd

A novel electrochemical immunosensor using MWCNTs–BMIMPF₆/NP-Pd as a sensor platform to sequentially immobilize antibodies was developed for hCG detection.