Microfluidic synthesis of Janus-structured QD-encoded magnetic microbeads for multiplex immunoassay

Microfluidic synthesis and accurate immobilization of low-density QD-encoded magnetic microbeads for multiplex immunoassay

Magnetic-fluorescent microbeads have been widely used in the multiplex detection of biological molecules. The traditional method relies on flow cytometry to decode and analyze the microbeads. Alternative strategies that employ immobilized microbeads on a plane and involve fluorescence imaging to analyze the microbeads have been proposed. Among these strategies, an integrated chip that controls magnetic field contribution using nickel powder pillars and captured microbeads has attracted great attention. Despite its unique advantages such as low manufacturing costs, reusability and high capture efficiency, existing research had been limited by the inability to precisely capture a single microbead, and the overlapping of microbeads has made multiplex immunoassays based on this strategy impossible. In this work, low-density microbeads were prepared in a microfluidic chip using IBOMA as the main monomer. The low density of the microbeads made the preparation of an aqueous suspension easier. An integration of nickel patterns, magnets and channels was carried out and demonstrated the capacity of capturing single microbeads precisely. Fluorescence coding further empowered this method with the ability of multiplex immunoassay, which was verified using three types of IgG, and a calibration curve for the detection of anti-human IgG was established using a sandwich immunoassay. These results show the promising potential of this strategy for biomedical detection.

Update on aquaporin-4 antibody detection: the early diagnosis of neuromyelitis optica spectrum disorders

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune-mediated primary inflammatory myelinopathy of the central nervous system that primarily affects the optic nerve and spinal cord. The aquaporin 4 antibody (AQP4-Ab) is a specific autoantibody marker for NMOSD. Most patients with NMOSD are seropositive for AQP4-Ab, thus aiding physicians in identifying ways to treat NMOSD. AQP4-Ab has been tested in many clinical and laboratory studies, demonstrating effectiveness in diagnosing NMOSD. Recently, novel assays have been developed for the rapid and accurate detection of AQP4-Ab, providing further guidance for the diagnosis and treatment of NMOSD. This article summarizes the importance of rapid and accurate diagnosis for treating NMOSD based on a review of the latest relevant literature. We discussed current challenges and methods for improvement to offer new ideas for exploring rapid and accurate AQP4-Ab detection methods, aiming for early diagnosis of NMOSD.

Automatic ultrasensitive lateral flow immunoassay based on a color-enhanced signal amplification strategy

Lateral flow immunoassays (LFIAs) are an essential and widely used point-of-care test for medical diagnoses. However, commercial LFIAs still have low sensitivity and specificity. Therefore, we developed an automatic ultrasensitive dual-color enhanced LFIA (DCE-LFIA) by applying an enzyme-induced tyramide signal amplification method to a double-antibody sandwich LFIA for antigen detection. The DCE-LFIA first specifically captured horseradish peroxidase (HRP)-labeled colored microspheres at the Test line, and then deposited a large amount of tyramide-modified signals under the catalytic action of HRP to achieve the color superposition. A limit of detection (LOD) of 3.9 pg/mL and a naked-eye cut-off limit of 7.8 pg/mL were achieved for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleoprotein. Additionally, in the inactivated virus detections, LOD equivalent to chemiluminescence (0.018 TCID50/mL) was obtained, and it had excellent specificity under the interference of other respiratory viruses. High sensitivity has also been achieved for detection of influenza A, influenza B, cardiac troponin I, and human chorionic gonadotrophin using this DCE-LFIA, suggesting the assay is universally applicable. To ensure the convenience and stability in practical applications, we created an automatic device. It provides a new practical option for point-of-care test immunoassays, especially ultra trace detection and at-home testing.