Water-soluble PEGylated silicon nanoparticles and their assembly into swellable nanoparticle aggregates

Abstract

Water-soluble silicon nanoparticles were synthesized by grafting PEG polymers onto functionalized silicon nanoparticles with distal alkyne or azide moieties. The surface-functionalized silicon nanoparticles were produced in one step from the reactive high-energy ball milling (RHEBM) of silicon wafers with a mixture of either 5-chloro-1-pentyne in 1-pentyne or 1,7 octadiyne in 1-hexyne to afford air and water-stable chloroalkyl or alkynyl-terminated nanoparticles, respectively. Nanoparticles with the xchloroalkyl substituents were easily converted to xazidoalkyl groups through the reaction of the Si nanoparticles with sodium azide in DMF. The azidoterminated nanoparticles were then grafted with mono-alkynyl-PEG polymers using a coppercatalyzed alkyne-azide cycloaddition (CuAAC) reaction to afford core-shell silicon nanoparticles with a covalently attached PEG shell. Covalently linked Si nanoparticle clusters were synthesized via the CuAAC ''click'' reaction of functional Si NPs with a,xfunctional PEG polymers of various lengths. Dynamic light scattering studies show that the flexible globular nanoparticle aggregates undergo a solvent-dependent change in volume (ethanol [ dichloromethane [ toluene) similar in behavior to hydrogel nanocomposites.

Mixed Surface Chemistry: An Approach to Highly Luminescent Biocompatible Amphiphilic Silicon Nanocrystals

“…Doubtless, this is partly because of the susceptibility of the SiNC surface to water-mediated oxidation . Still, a variety of approaches for making water-compatible SiNCs have been explored; they include direct functionalization with ligands bearing carboxylic acid, , amine, − or hydroxyl , terminal groups, as well as amino acids, sugars, , and hydrophilic polymers. , Other approaches have also seen micelle encapsulation of hydrophobic ligand-capped SiNCs using amphiphilic polymers or lipids. ,, To date, only one report of blue-emitting amphiphilic SiNCs (AP-SiNCs) exhibiting nanosecond excited states has appeared in which NCs were modified using Pt-mediated hydrosilylation …”

Polyethylene glycol-coated blue-emitting silicon dots with improved properties for uses in aqueous and biological environments

“…Conformation may also affect the coating shielding of the reactive zero-dimensional silicon semiconductor core, thus determining the SiDs chemical and optical stability in aqueous suspensions. Accomplishing successful PEGylation of SiDs depends on the synthesis procedure used for obtaining the silicon core, its surface chemistry, and the method used for conjugation, as demonstrated by recent literature reports on the multistep synthesis of PEG-coated SiDs [8,16].…”

Functionalized silicon nanoparticles from reactive cavitation erosion of silicon wafers

“…The fact that photoluminescent product begins to elute at fraction 5 (25 mL elution volume) indicates that there were smaller size particles in this sample than those formed by mechanochemical methods reported in the literature which have diameters in the 5-10 nm range and elute with only B15 mL of the mobile phase. 31,32 The small nanoparticle sizes (o1 nm) are further supported by TEM investigations which show a proliferation of sub-1 nm nanoparticles down to the resolution of the instrument (about 1 nm), with EDS analysis of these same samples indicating the presence of elemental Si (see ESI, † Fig. S3).…”