Multimodal magneto-plasmonic nanoclusters for biomedical applications

Multimodal nanostructures can help solve many problems in the biomedical fi eld including sensitive molecular imaging, highly specifi c therapy, and early cancer detection. However, the synthesis of densely packed, multicomponent nanostructures with multimodal functionality represents a signifi cant challenge. Here, a new type of hybrid magneto-plasmonic nanoparticles is developed using an oil-in-water microemulsion method. The nanostructures are synthetized by self-assembly of primary 6 nm iron oxide core-gold shell particles resulting into densely packed spherical nanoclusters. The dense packing of primary particles does not change their superparamagnetic behavior; however, the close proximity of the constituent particles in the nanocluster leads to strong near-infrared (NIR) plasmon resonances. The synthesis is optimized to eliminate nanocluster cytotoxicity. Immunotargeted nanoclusters are also developed using directional conjugation chemistry through the Fc antibody moiety, leaving the Fab antigen recognizing region available for targeting. Cancer cells labeled with immunotargeted nanoclusters produce a strong photoacoustic signal in the NIR that is optimum for tissue imaging. Furthermore, the labeled cells can be effi ciently captured using an external magnetic fi eld. The biocompatible magneto-plasmonic nanoparticles can make a signifi cant impact in development of point-of-care assays for detection of circulating tumor cells, as well as in cell therapy with magnetic cell guidance and imaging monitoring.