Photothermal Soft Nanoballs Developed by Loading Plasmonic Cu2-xSe Nanocrystals into Liposomes for Photothermal Immunoassay of Aflatoxin B1

Photothermal effects (PTEs) have been greatly concerned with the fast development of new photothermal nanomaterials. Herein we propose a photothermal immunoassay (PTIA) by taking mycotoxins (AFB(1)) as an example based on the PTEs of plasmonic Cu2-xSe nanocrystals (NCs). By loading plasmonic Cu2-xSe NCs into liposomes to form photothermal soft nanoballs (ptSNBs), on which aptamer of AFB, previously assembled, a sandwich structure of AFB(1) could be formed with the aptamer on ptSNBs and capture antibody. The heat released from the ptSNBs under NIR irradiation, owing to the plasmonic photothermal light-to-heat conversion through photon electron phonon coupling, makes the temperature of substrate solution increased, and the increased temperature has a linear relationship with the AFB(1) content. Owing to the large amounts of plasmonic Cu2-xSe NCs in the ptSNBs, the PTEs get amplified, making AFB(1) higher than 1 ng/mL detectable in food even if with a rough homemade immunothermometer. The proposal of PTIA opens a new field of immunoassay including developing photothermal nanostructures, new thermometers, PTIA theory, and so on.