Surface modified ultrasmall nanoparticles as dual labelled imaging agents

The development of multimodal imaging agents for biomedical applications is a growing field of research. The idea behind the use of nuclear and optical dual labelled imaging probes is the possibility to synergistically exploit the advantages of positron emission tomography (PET) and optical imaging. The use of dual imaging probes enhances sensitivity, spatial and temporal resolution, tissue penetrability and allows the simultaneous acquisition of complementary information which can improve diagnosis and treatment of diseases.
The utilization of nanomaterials in medicine holds a promising potential in emerging applications of diagnostic imaging as well as the prospect of new capabilities for delivering targeted therapies tailored for specific diseases. Due to their biocompatibility, luminescence properties and the possibility to covalently functionalize their surface, water-soluble ultrasmall (<5 nm) silicon nanoparticles (SiNPs) are excellent candidates in this perspective.(1,2)
Amine-terminated ultrasmall silicon nanoparticles were prepared according to a reported method with slight modifications.(3) Here we report the functionalization of amine-terminated SiNPs with the sulfo-cyanine 5 dye (sCy5) to obtain an optical imaging probe and with biomolecules, such as single-domain antibodies (sdAb) for active targeting of a cancer biomarker. SiNPs are also modified with radiolabel such as 64Cu, coordinated to bispidines(4), to obtain a dual, nuclear and optical, probe.
The functionalization of SiNPs with dyes, radiotracers and targeting molecules will open the path for targeted dual imaging of cancer, possibly allowing diagnosis and therapy in in vivo systems.

References
1) M. Rosso-Vasic et al., J. Mater. Chem. 2009, 19, 5926.
2) C. -H. Lai et al., Nano Lett. 2016, 16, 807−811.
3) Y. Zhong et al., J. Am. Chem. Soc. 2013, 135, 8350.
4) H. Stephan et al., Chem. Eur. J. 2014, 20, 17011.