Multifunctional mesoporous silica nanoparticles as labels for the preparation of ultrasensitive electrochemical immunosensors

Labels based on mesoporous silica nanoparticles (MSN) loaded with mediator thionine (TH), enzyme horseradish peroxidase (HRP) and secondary anti-human IgG antibody (Ab2) were developed in order to improve the sensitivity and detection limit of an amperometric immunosensor. The sensitivity of the sandwich-type immunosensor using MSN–TH–HRP–Ab2 as labels for human IgG detection was about 100 times higher than that using either MSN–TH–Ab2 or MSN–HRP–Ab2 as labels, indicating the high catalytic efficiency of HRP in the presence of mediator TH toward H2O2. The immunosensor using MSN–TH–Ab2 as labels exhibited a high sensitivity and showed a linear response within the range of 0.01–10 ng/mL human IgG. It also showed good reproducibility and selectivity and acceptable stability. These labels for immunosensors may provide many potential applications for the detection of different biomolecules.