Ratiometric quantification of β2-microglobulin antigen in human serum based on elemental labeling strategy

Highly sensitive detection of aflatoxin B1 byCRISPR/Cas12a-assisted single nanoparticle counting

CRISPR (clustered regularly interspaced short palindromic repeats) and CRISPR-associated protein (Cas) have gained extensive applications in bioassays. However, CRISPR-based detection platforms are often hampered by limited analytical sensitivity, while nucleic acid-based amplification strategies are usually indispensable for additional signal enhancement with potential risks of amplification leakages. To address these challenges, an amplification-free CRISPR-based bioassay of aflatoxin B1 (AFB1) was proposed by applying single nanoparticle counting. Single-particle mode inductively coupled plasma mass spectrometry (Sp-ICPMS) has been regarded as a sensitive tool for nanoparticle counting since one nanoparticle can generate considerable signals above backgrounds. With AFB1, activator strands were introduced to initiate the trans-cleavage of CRISPR/Cas12a for cutting the nanoparticles-tagged-magnetic beads, which were transduced to nanoparticle count signals after separation. Finally, a pico-mole level limit-of-detections (LODs) with moderate selectivity was achieved. Certified reference materials (CRMs) analysis and recovery tests were conducted with promising results. To our best knowledge, this is the first report of the single particle counting-based CRISPR/Cas12a biosensing study.

Au@NiFeMOFs as the signal quencher of Au@g-C3N4NSs composite for sensitive "on-off" electrochemiluminescence immunosensing of beta-2-microglobulin

In this study, an electrochemiluminescence resonance energy transfer (ECL-RET) immunosensor was constructed to detect beta-2-microglobulin (B2M). As a donor-acceptor pair, a carbon nitride nanosheet modified with gold nanoparticles (Au@g-C₃N₄NSs) and a nickel- and iron-based organic framework modified with gold nanoparticles (Au@NiFeMOFs) were prepared. The sandwich immunosensor was successfully constructed so that ECL-RET occurred between Au@NiFeMOFs and Au@g-C₃N₄NSs. The ECL intensity of the immunosensor decreased with the increase the B2M concentration due to the low conductivity of B2M. The linear range of the ECL-RET immunosensor was from 10 fg/mL to 10 ng/mL, and the limit of detection was 2.3 fg/mL (S/N = 3). The developed immunosensor had high sensitivity, high specificity, and excellent stability. It could realize the sensitivity test of B2M and provide a novel idea for the detection of biomarkers.

Lifting the Veil: Characteristics, Clinical Significance, and Application of β-2-Microglobulin as Biomarkers and Its Detection with Biosensors

Because β-2-microglobulin (β₂M) is a surface protein that is present on most nucleated cells, it plays a key role in the human immune system and the kidney glomeruli to regulate homeostasis. The primary clinical significance of β₂M is in dialysis-related amyloidosis, a complication of end-stage renal disease caused by a gradual accumulation of β₂M in the blood. Therefore, the function of β₂M in kidney-related diseases has been extensively studied to evaluate its glomerular and tubular functions. Because increased β₂M shedding due to rapid cell turnover may indicate other underlying medical conditions, the possibility to use β₂M as a versatile biomarker rose in prominence across multiple disciplines for various applications. Therefore, this work has reviewed the recent use of β₂M to detect various diseases and its progress as a biomarker. While the use of state-of-the-art β₂M detection requires sophisticated tools, high maintenance, and labor cost, this work also has reported the use of biosensor to quantify β₂M over the past decade. It is hoped that a portable and highly efficient β₂M biosensor device will soon be incorporated in point-of-care testing to provide safe, rapid, and reliable test results.

Highly sensitive and multiplexed mass spectrometric immunoassay techniques and clinical applications

Immunoassay is one of the most important clinical techniques for disease/pathological diagnosis. Mass spectrometry (MS) has been a popular and powerful readout technique for immunoassays, generating the mass spectrometric immunoassays (MSIAs) with unbeatable channels for multiplexed detection. The sensitivity of MSIAs has been greatly improved with the development of mass labels from element labels to small-molecular labels. MSIAs are also expended from the representative element MS-based methods to the laser-based organic MS and latest ambient MS, improving in both technology and methodology. Various MSIAs present high potential for clinical applications, including the biomarker screening, the immunohistochemistry, and the advanced single-cell analysis. Here, we give an overall review of the development of MSIAs in recent years, highlighting the latest improvement of mass labels and MS techniques for clinical immunoassays.