Silicon Nanoparticles: From Synthesis, Characterization to Application in Biomedicine

Silicon Nanoparticles (Si NPs) have been studied for twenty years, and recently they have received a lot of attention because of their potential use in in vitro1and in vivo imaging2,3. Indeed Si NPs have shown no toxicity when uptaken by cells4, and display interesting luminescence properties as well as photo- and electro- stability which are suitable also for photoelectron application.5,6 Here we report on the synthesis of Si NPs via wet chemistry methods either by reducing Si(OMe)4 in reverse micelle1,7 or oxidizing Mg₂Si8. The size of Si NPs is 1.6 nm and 3.9 nm, respectively. The Si NPs have been characterized by high resolution transmission electron microscopy (HRTEM), infrared spectroscopy (IR), and their photophysical properties were investigated. The Si NPs exhibit very bright luminescence that is strongly dependent on their size, as already known, and can be functionalized with a variety of groups allowing different solubility and further derivatization. We indeed show that different labels can be covalently attached and even targeting groups can be attached for multimodal bio-imaging. The first experiments in in vivo conditions will be shown to demonstrate the potentiality of these ultrasmall particles.

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