PEG-coated blue-emitting silicon dots with improved properties for uses in aqueous and iological envinonments

ROMERO, JUAN JOSÉ; FERNANDEZ LORENZO DE MELE, MONICA; LILLO, CRISTIAN; MIÑAN, ALEJANDRO; RODRIGUEZ SARTORI, DAMIAN; DELL'ARCIPRETE, MARIA LAURA; GONZALEZ, MONICA

NANOTECHNOLOGY

IOP PUBLISHING LTD

Lugar: Londres; Año: 2016 vol. 27 p. 5704 - 5714

0957-4484

Polyethylene glycol (PEG) grafting to ultrasmall photoluminescent silicon nanoparticles (SiDs) is expected to improve and expand the applications of these particles to aqueous environments and biological systems. In this report, the novel one-pot synthesis of PEG-coated SiDs (denoted as PEG-SiDs) based on the liquid phase oxidation of magnesium silicide using PEG as reaction media and leading to high PEG density grafting is described. PEG-SiDs photophysical, photosensitizing, and solution properties in aqueous environments are described and compared to those of PEG-coated SiDs with low PEG density grafting (denoted as PEG-NHSiDs) obtained from a multistep synthesis strategy. In summary, PEG-SiDs were of (3.3 ± 0.5) nm size with an estimated silicon core of approximately 1.3 ? 1.7 nm, are highly dispersed in water solvent, showed stable photoluminescence quantum yields F = 0.13 at 370 nm excitation in air-saturated aqueous suspensions, and exhibited the capacity of photosensitizing the formation of singlet molecular oxygen, not observed for PEG-NHSiDs. PEG robust shielding of the silicon core luminescent properties is further demonstrated in bio-imaging experiments stressing the strong interaction between PEG-SiDs and S. aureus smears by observing the particles own photoluminescence. PEG-SiDs were found nontoxic to S. Aureus cells already at concentrations of 100 mg/ml, though a bacteriostatic effect on S. aureus biofilms was observed upon UV-A irradiation under conditions were light alone has no effect.