Magnetic Bead-Sensing-Platform-Based Chemiluminescence Resonance Energy Transfer and Its Immunoassay Application

A competitive immunoassay based on chemiluminescence resonance energy transfer (CRET) on the magnetic beads (MBs) is developed for the detection of human immunoglobulin G (IgG). In this protocol, carboxyl-modified MBs were conjugated with horseradish peroxidase (HRP)-labeled goat antihuman IgG (HRP-anti-IgG) and incubated with a limited amount of fluorescein isothiocyanate (FITC)-labeled human IgG to immobilize the antibody–antigen immune complex on the surface of the MBs, which was further incubated with the target analyte (human IgG) for competitive immunoreaction and separated magnetically to remove the supernatant. The chemiluminescence (CL) buffer (containing luminol and H₂O₂) was then added, and the CRET from donor luminol to acceptor FITC in the immunocomplex on the surface of MBs occured immediately. The present protocol was evaluated for the competitive immunoassay of human IgG, and a linear relationship between CL intensity ratio (<i><i>R</i> = I</i>₄₂₅/<i>I</i>₅₂₅) and human IgG concentration in the range of 0.2–4.0 nM was obtained with a correlation coefficient of 0.9965. The regression equation was expressed as <i>R</i> = 1.9871<i>C</i> + 2.4616, and a detection limit of 2.9 × 10^–11 M was obtained. The present method was successfully applied for the detection of IgG in human serum. The results indicate that the present protocol is quite promising for the application of CRET in immunoassays. It could also be developed for detection of other antigen–antibody immune complexes by using the corresponding antigens and respective antibodies

A Macrophage Membrane-Coated Cu–WO_3–<i>x</i>-Hydro820 Nanoreactor for Treatment and Photoacoustic/Fluorescence Dual-Mode Imaging of Inflamed Liver Tissue

A disease-targeting nanoplatform that integrates imaging with therapeutic activity would facilitate early diagnosis, treatment, and therapeutic monitoring. To this end, a macrophage membrane-coated Cu–WO3–x-Hydro820 (CWHM) nanoreactor was prepared. This reactor was shown to target inflammatory tissues. The reactive oxygen species (ROS) such as H2O2 and ·OH in inflammatory tissues can react with Hydro820 in the reactor to form the NIR fluorophore IR820. This process allowed photoacoustic/fluorescence dual-mode imaging of H2O2 and ·OH, and it is expected to permit visual diagnosis of inflammatory diseases. The Cu–WO3–x nanoparticles within the nanoreactor shown catalase and superoxide enzyme mimetic activity, allowing the nanoreactor to catalyze the decomposition of H2O2 and ·O2– in inflammatory cells of hepatic tissues in a mouse model of liver injury, thus alleviating the oxidative stress of damaged liver tissue. This nanoreactor illustrates a new strategy for the diagnosis and treatment of hepatitis and inflammatory liver injury