An immunoassay based on nanomotor-assisted electrochemical response for the detection of immunoglobulin.

An immunoassay strategy has been developed based on nanomotor-assisted electrochemical measurements for simple and sensitive detection of immunoglobulin (IgG). The self-propelled Fe 3 O 4 @SiO 2 /Pt nanomotors were designed to label primary antibodies IgG (nanomotor-label) for the "on-the-fly" binding of the immune-protein. The core shell Au@Ag nanocubes (Au@Ag NCs) were used as labels of secondary antibodies (Au@Ag NCs-Ab 2 ) to amplify electrochemical signal related to antigen concentration derived from the oxidation of Ag. The self-propelled nanomotors autonomously move in the solution to cruise and capture IgG and Au@Ag NCs-Ab 2 , resulting in the self-assembly of sandwich immune-complex. Finally, the immune-complex with magnetism can be transferred and modified on the electrode for the detection of IgG via differential pulse voltammetry. The self-propelled motion of the nanomotor-label obviates common procedures for the self-assembly of sandwich immunosensors to achieve satisfactory analysis results. With advantages of automation and miniaturization, the strategy based on self-propelled nanomotor-labels explores an effective method for the simple and sensitive detection of immune-protein in biosensing.