Colloidally Stable Silicon Nanocrystals with Near‐Infrared Photoluminescence for Biological Fluorescence Imaging

Abstract

Luminescent silicon nanocrystals (ncSi) are showing great promise as photoluminescent tags for biological fluorescence imaging, with size-dependent emission that can be tuned into the near-infrared biological window and reported lack of toxicity. Here, colloidally stable ncSi with NIR photoluminescence are synthesized from (HSiO1.5)n sol-gel glasses and are used in biological fluorescence imaging. Modifications to the thermal processing conditions of (HSiO1.5)n sol-gel glasses, the development of new ncSi oxide liberation chemistry, and an appropriate alkyl surface passivation scheme lead to the formation of colloidally stable ncSi with photoluminescence centered at 955 nm. Water solubility and biocompatibility are achieved through encapsulation of the hydrophobic alkyl-capped ncSi within PEG-terminated solid lipid nanoparticles. Their applicability to biological imaging is demonstrated with the in-vitro fluorescence labelling of human breast tumor cells.

Colloidal silicon quantum dots: synthesis and luminescence tuning from the near-UV to the near-IR range

“…It has been shown that ligand-stabilized nanocrystals can be easily tuned to emit from the near-UV (NUV) through visible (VIS) to the near-IR (NIR) region with varying size and surface. These advantages make it an ideal material for solution processable applications [28–32]. However, the story does not end here.…”

Vesicular hydrogen silsesquioxane-mediated synthesis of nanocrystalline silicon dispersed in a mesoporous silica/suboxide matrix, with potential for electrochemical applications

“…1,2 During lithium insertion, however, silicon undergoes volume expansion -including the fourfold increase in unit cell volume observed in the case of Li 22 Si 5 . 3 This reversible expansion and contraction with repeated cycling results in crack formation and disintegration of the electrode leading to loss of conductivity, decrease in specific capacity and short cycle life of the battery.…”

Cationic Silicon Nanocrystals with Colloidal Stability, pH‐Independent Positive Surface Charge and Size Tunable Photoluminescence in the Near‐Infrared to Red Spectral Range

“…Steric stabilization strategies typically use long poly(ethylene glycol) chains to achieve colloidal stability. The use of solid lipid nanoparticles by Henderson et al and phospholipid micelles by Erogbogbo et al are prime examples 13, 14, 15. Electrostatic stabilization strategies rely on ionic ligands to prevent flocculation, commonly used ones include olefins with terminal carboxylic acids and terminal primary amines 8, 12, 15, 16, 17, 18, 19, 20.…”