Deoxycholate as an efficient coating agent for hydrophilic silicon nanocrystals.

Silicon nanocrystals were made hydrophilic by 10-undecenoic acid grafting and were then coated with sodium deoxycholate, a detergent-like compound belonging to the bile acid class which is crucial for absorption of lipids in the small intestine. The resulting silicon nanocrystals have an average diameter of 3–5 nm, can be dispersed in aqueous solutions and show stable photoluminescence. Coating with non-biological surfactants, which are dangerous for cell safety, was investigated for comparison. Results indicate that deoxycholate is a stabilizer of luminescent silicon nanocrystals. Deoxycholate coated nanocrystals appear suitable for applications as multifunctional probes in biomedicine. Graphical abstract Water soluble, light emitting silicon nanocrystals were obtained by a two-step procedure: a chemical grafting followed by physical coating by deoxycholate which is natural surfactant-like molecule well tolerated by cells. This compound maintained the bright nanocrystal luminescence emission stable for 4–5 days.