A multicolor nano-immunosensor for the detection of multiple targets

This work reports the design of a novel peptide antigen-based multicolor fluorescent gold nanoparticles (AuNP) immunosensor for multiplex detection of peptides and proteins in homogeneous solution. The three involved peptides were first labeled with three different fluorescent dyes at their N-terminus, and the dye-labeled peptide antigens were then reacted with AuNPs functionalized with three relevant antibodies to obtain a multicolor fluorescent AuNPs immunosensor. In the presence of target molecules, the dye-labeled peptide antigens were released from the AuNPs surface because of competitive immunoreactions, generating higher fluorescence that provided signal readout for the immunosensing process. Importantly, the large surface area of the AuNPs allows simultaneous quenching of multiple peptide antigens labeled with different dyes via the binding with AuNPs-conjugated antibodies, leading to a multicolor nano-immunosensor for the detection of multiple targets in same solution. Furthermore, the application of this AuNPs-based multicolor fluorescent immunosensor for complex biological sample analysis is also demonstrated. This approach offers high sensitivity and selectivity, and promises an efficient platform for low-cost multiplexed immunoassay of biomolecules.