2.3. POCT Applications of MANP in Ultrasensitive Immunochromatographic Detection.
The remarkable magneto-fluorescence retention and prominent stability of MANP6:6 make it practical for biomedical applications. In this study, we further investigated the feasibility of MANP6:6 as a dual-functional magnetic separation and fluorescent nanoprobe in the field of POCT, specifically using LFIA as the detection platform. Scheme 1 depicts the construction principle of the MANP-FLIA platform for ultrasensitive detection of targets in human serum/urine. The assay is based on a double-antibody sandwich immunoassay format. When the targets are present in serum or urine, the antigens are initially bound to monoclonal antibodies modified MANP6:6 (MANP6:6@mAbs), forming a MANP6:6@mAbs immunocomplex. The immunocomplex is then collected by an external magnetic field and resuspended in buffer solution. The complex solution was then applied to the LFIA test strip, which has antibodies immobilized on the NC membrane. This results in the formation of a nanoprobe/antigen/antibody sandwich architecture on the T line with high fluorescent signals (FIT). Additionally, excess MANP6:6@mAbs are captured by the goat anti-mouse IgG on the C line, producing a corresponding fluorescent signal (FIC). In the absence of the targets, the MANP6:6@mAbs run to the C line and react with the IgG. The presence or absence of fluorescent lines provide a direct visual diagnosis result: one line (C) indicates a negative result for the targets, whereas two lines (T + C) indicate a positive result. In addition, the ratio of FIT/FIC is used to accurately quantify the target concentration, which effectively circumvents the intensity fluctuations by employing a ratiometric strategy.