title: Polyethylene glycol-coated blue-emitting silicon dots with improved properties for uses in aqueous and biological environments.
abstract: Grafting of polyethylene glycol (PEG) to ultrasmall photoluminescent silicon dots (SiDs) is expected to improve and expand the applications of these particles to aqueous environments and biological systems. Herein we report a novel one-pot synthesis of robust, highly water compatible PEG-coated SiDs (denoted as PEG-SiDs) of (3.3 ± 0.5) nm size. The nanoparticles' synthesis is based on the liquid phase oxidation of magnesium silicide using PEG as reaction media and leading to high PEG density grafting. PEG-SiDs enhanced photophysical, photosensitising, and solution properties in aqueous environments are described and compared to those of 2 nm size PEG-coated SiDs with low PEG density grafting (denoted as PEG-NHSiDs) obtained from a multistep synthesis strategy. PEG-SiDs form highly dispersed suspensions in water showing stable photoluminescence and quantum yields of Φ = 0.13 ± 0.04 at 370 nm excitation in air-saturated suspensions. These particles exhibited the capacity of photosensitising 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 Staphylococcus aureus smears by observing the photoluminescence of particles. PEG-SiDs were found to be nontoxic to S. aureus cells at concentrations of 100 mg ml-1, though a bacteriostatic effect on S. aureus biofilms was observed upon UV-A irradiation under conditions where light alone has no effect.
authors: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Casilla de Correo 16, Suc. 4, (1900) La Plata, Argentina.
authors: Damián
authors: D
authors: Rodríguez Sartori
authors: Cristian R
authors: CR
authors: Lillo
authors: Juan J
authors: JJ
authors: Romero
authors: María
authors: M
authors: Laura Dell Arciprete
authors: Alejandro
authors: A
authors: Miñán
authors: Mónica
authors: M
authors: Fernández Lorenzo de Mele
authors: Mónica C
authors: MC
authors: Gonzalez
mesh_terms: D011092:Polyethylene Glycols / Q000737:chemistry*; D012825:Silicon; D013211:Staphylococcus aureus; D013535:Suspensions; D014867:Water
chemical_list: D013535:Suspensions; D014867:Water; D011092:Polyethylene Glycols; D012825:Silicon