Fabrication of the water-soluble functionalized silicon nanoparticles for biomedical applications

Functionalized water-soluble silicon nanoparticles were fabricated and applied in biomedical imaging. Firstly, hydrophobic hydride-capped silicon nanoparticles (H-SiNPs) were synthesized by hydrogen silsesquioxane, subsequently modified by allylthiourea and further chelated with gadopentetate dimeglumine (Gd-DTPA) to fabricate water-soluble functionalized SiNPs. Fourier transform infrared technology and X-ray photoelectron spectroscopy evidenced the successful function. The properties of functionalized SiNPs were significantly improved including fluorescence intensity, photoluminescence quantum yield (from 0.87 to 14.04%), fluorescence lifetimes (from 29.9 to 63.8 μs), photo-stability, biocompatibility, etc. Hematoxylin and eosin (H&E) staining assay further demonstrated the low toxicity and the satisfactory biocompatibility of Gd-SiNPs. The longitudinal relaxation (r 1 ) of Gd-SiNPs was measured to be 11.59 mM −1 s −1 and much higher than that of the commercial contrast agent Gd-DTPA (4.29 mM −1 s −1 ). Finally, the charming Gd-SiNPs were successfully applied as a biologic probe in fluorescence and magnetic resonance dual-mode imaging in vivo and in vitro. Graphical abstract Fabrication of the water-soluble functionalized silicon nanoparticles and their application in fluorescence and magnetic resonance dual-mode bioimaging