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.