Abstract:

Purpose: To fabricate a biosensor based on sulforhodamine B sodium salt (SRB)-encapsulating liposomes
for highly sensitive detection of human IgG (hIgG). Methods: An immunoliposome encapsulating SRB was prepared
and used to develop a fluorescent biosensor by the film dispersion method. Magnetic beads (MB) were employed as
the immobilization and separation carrier. By enzyme-linked immunospecific assay (ELISA) method, MB modified
anti-IgG antibodies were linked to SRB-encapsulating liposomes, which instantaneously released a great quantity of
SRB molecules upon alcohol addition, resulting in highly sensitive fluorescent detection of hIgG. SRB-encapsulating
liposomes had good stability in 10 days. The optimized condition was as follows: 60 μg of MB modified anti-IgG
antibody and 0.2 μg of biotin-labeled anti-IgG antibody Results: The lowest detectable concentration of hIgG was 1 ng/mL (6.25
pmol/L), and the linear range was 1 to 200 ng/mL. Conclusions: This lable-free protocol can provide a rapid, simple and
sensitive approach to detecting IgG.

Key words: liposomes, magnetic beads, immunoglobulin, biosensor, fluorescent analysis