Facile Formation of Stable Water‐Dispersed Luminescent Silicon Nanocrystals by Laser Processing in Liquid: Toward Fluorescent Labeling for Bio‐Imaging

Abstract

We herein develop a facile formation process of a water‐dispersed red luminescent undecenoic acid‐functionalized silicon nanocrystal (UA‐F: Si‐nc) via pulsed laser irradiation of porous silicon (PSi) in an organic solvent. The formed UA‐F: Si‐nc has a high stability against pH changes in aqueous solution and photo‐irradiation in water without any multi‐step surface treatments. Such a robust aqueous surface protection of Si‐nc is caused by hydrophilic organic group terminations and subsequent surface protection of OH bonding. From the viability and in vitro bio‐imaging tests against Hela cells and A549 cells, we confirmed that UA‐F: Si‐nc has very low cytotoxicity due to the essential biocompatibility of silicon and remains exhibiting a bright red luminescence in the cells. Because of its high stability in water as well as biocompatibility, UA‐F: Si‐nc is expected to act as a fluorescent label of cellular imaging.