Ultrasmall silicon nanoparticles as promising platform for multimodal imaging

Ultrasmall renal clearable nanoparticles possess enormous potential as cancer imaging agents [1, 2]. In this perspective, biocompatible silicon nanoparticles (Si NPs) are highly attractive. Their facile surface functionalization allows the introduction of different labels for in vivo imaging. Recently, we have reported on biodistribution of ultrasmall silicon particles (size ~ 4 nm) in small animals by in vivo positron emission tomography (PET) to provide reliable information about absorption, distribution, metabolism, and excretion (ADME) [3].
Subsequent functionalization of Si NPs with a near-infrared dye (IR800-CW) and a radiolabel (64Cu) enabled a detailed in vitro and in vivo study of the particles of these dual labeled particles. Both PET and fluorescence imaging studies showed a rapid renal clearance from small animals. It has been proven that ultrasmall Si NPs with a surface charge close to zero show fast distribution kinetics and rapid renal clearance. Despite the very small size, multiple and different functionalities can be grafted on the nanoparticle surface. In this way, the pharmacokinetic properties can be tailored and the behavior can be studied in vitro and in vivo in detail.

[1] Zarschler et al. Nanomedicine: Nanotechnology, Biology, and Medicine. 2016, 12: 1663-1701.
[2] Kunz-Schughart et al. Biomaterials 2017, 120: 155-184.