Magnetized Carbon Nanotube Based Lateral Flow Immunoassay for Visual Detection of Complement Factor B

Abstract

The authors describe a magnetized carbon nanotube (MCNT) based lateral flow immunoassay (LFI) for visual detection of complement factor B (CFB) in blood. MCNT was prepared by decorating magnetic Fe3O4 nanoparticles on multi-walled CNT surface and used as a colored tag for LFI. Monoclonal antibody (mAb, Ab1) of CFB was covalently immobilized on the MCNT surface via diimide-activated conjugation between the carboxyl groups on the MCNT surface and amino groups of antibodies. Polyclonal antibody of CFB (Ab2) and the secondary antibody were used to prepare the lateral flow test strips. The assay involved: (1) the capture of CFB in blood with the mAb-functionalized MCNT; (2) magnetic separation of the formed CFB-mAb-MCNT and excess of mAb-MCNT from the blood with an external magnet; (3) lateral flow test to capture the CFB-mAb-MCNT complex on the test zone and the excess of mAb-MCNT on the control zone; (4) Recording the intensities of the produced the characteristic brown bands with a portable strip reader and quantitating the concentration of CFB. The proof-of-concept was demonstrated by testing CFB in the buffer, and the detection limit was 5 ng mL−1 under the optimized analytical parameters. CFB in 1 μL of human blood was detected successfully in 30 min with this LFI and the results had a high correlation with commercial ELISA kit. Thence, the MCNT-based LFI offers a rapid and low-cost tool for detecting CFB in human blood directly.

Ultrasensitive Detection of Severe Fever with Thrombocytopenia Syndrome Virus Based on Immunofluorescent Carbon Dots/SiO2 Nanosphere-Based Lateral Flow Assay

“…Most studies on carbon materials as signal reporters for test strips mainly include carbon colloids and carbon nanotubes, which can help to visually observe the test results. ,,− They are more sensitive, stable, and environmentally friendly than gold particles. Fluorescent carbon dots (CDs) are a member of QDs and are a new class of zero-dimensional nanomaterials in the carbon family.…”

Ultra-Trace Protein Detection by Integrating Lateral Flow Biosensor with Ultrasound Enrichment

“…GNP−antibody conjugates were prepared according to the reported methods with slight modifications, that is, the antibody was changed to goat anti-Rabbit IgG. 21 LFBs were manufactured according to the reported methods. 22 Description of Ultrasonic Device.…”

“…Materials such as nylon, nitrocellulose (NC) membranes, , glass fiber, hydrogel, and whole blood separation membrane have been used as filters to pretreat oral fluids, drinking water samples, serum, lysed blood, and whole blood in the LFBs. In the last 10 years, magnetic separation as a convenient method has been widely used as a sample pretreatment approach to separate bacterial or protein biomarkers from the complex matrix such as blood, milk, and cytosol. − Recently, ultrasound actuation with swarming or assembling behavior exhibits excellent ability of regulating nanoparticles − and has a profound impact upon diverse applications such as propelling nanowires and manipulating cells. − Last year, our group integrated the ultrasound pre-treatment approach with surface-enhanced Raman scattering and fluorescence to achieve ultra-trace detection of nucleic acids. Compared with magnetic or other separation methods, ultrasound pre-treatment responds quickly (just in seconds), disregards the morphology or size of particles, and is easy to control, thus providing an opportunity as a pre-treatment approach to integrate LFBs to enrich and detect ultra-trace biomarkers for clinical diagnosis.…”