Development of cost-effective and highly efficient nanoscale contrast agents for targeted dual mode imaging of tumors still remains a great challenge. Here, we report the synthesis of folic acid (FA)-modified multifunctional low-generation dendrimer-entrapped gold nanoparticles (Au DENPs) labeled with 99mTc for targeted dual-mode single photon emission computed tomography (SPECT)/computed tomography (CT) imaging of tumors. In this work, amine-terminated generation 2 poly(amidoamine) (PAMAM) dendrimers (G2.NH2) modified with chelator DTPA via a amide linkage and FA via a polyethylene glycol (PEG) spacer were used as templates to entrap AuNPs. Further chelation of 99mTc led to the formation of multifunctional FA-targeted Au DENPs labeled with 99mTc (G2-DTPA-PEG-FA@Au-99mTc). The formed G2-DTPA-PEG-FA@Au NPs before and after 99mTc labeling were characterized via different techniques. We show that the formed G2-DTPA-PEG-FA@Au NPs with a mean Au core size of 1.6 nm are water-dispersible, colloidally stable under different temperature and pH conditions, and cytocompatible in the studied concentration range. Importantly, the co-existence of the AuNPs and 99mTc within the single multifunctional particles affords their uses as a nanoprobe for targeted SPECT/CT dual-mode imaging of FA receptor (FAR)-expressing HeLa cells in vitro and the xenografted tumor model in vivo within a time frame up to 3 h. With the demonstrated organ compatibility, the developed G2-DTPA-PEG-FA@Au-99mTc NPs using low-generation dendrimers may hold great promise to be used as a highly efficient and cost-effective nanoprobe for targeted SPECT/CT imaging of different FAR-expressing tumors.

99mTc-labeled multifunctional low-generation dendrimer-entrapped gold nanoparticles as a platform for targeted dual mode SPECT/CT imaging of tumors

251st National Meeting (2016)

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