Hybrid Silver Nanocubes for Improved Plasmon-Enhanced Singlet Oxygen Production and Inactivation of Bacteria

J Am Chem Soc. 2019 Jan 9;141(1):684-692. doi: 10.1021/jacs.8b12206. Epub 2018 Dec 20.

Abstract

Plasmonic nanoparticles can strongly interact with adjacent photosensitizer molecules, resulting in a significant alteration of their singlet oxygen (1O2) production. In this work, we report the next generation of metal-enhanced 1O2 nanoplatforms exploiting the lightning rod effect, or plasmon hot spots, in anisotropic (nonspherical) metal nanoparticles. We describe the synthesis of Rose Bengal-decorated silica-coated silver nanocubes (Ag@SiO2-RB NCs) with silica shell thicknesses ranging from 5 to 50 nm based on an optimized protocol yielding highly homogeneous Ag NCs. Steady-state and time-resolved 1O2 measurements demonstrate not only the silica shell thickness dependence on the metal-enhanced 1O2 production phenomenon but also the superiority of this next generation of nanoplatforms. A maximum enhancement of 1O2 of approximately 12-fold is observed with a 10 nm silica shell, which is among the largest 1O2 production metal enhancement factors ever reported for a colloidal suspension of nanoparticles. Finally, the Ag@SiO2-RB NCs were benchmarked against the Ag@SiO2-RB nanospheres previously reported by our group, and the superior 1O2 production of Ag@SiO2-RB NCs resulted in improved antimicrobial activities in photodynamic inactivation experiments using both Gram-positive and -negative bacteria model strains.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Escherichia coli / drug effects
  • Escherichia coli / metabolism
  • Escherichia coli / physiology
  • Escherichia coli / radiation effects
  • Microbial Viability / drug effects*
  • Microbial Viability / radiation effects
  • Nanotubes / chemistry*
  • Photosensitizing Agents / chemistry*
  • Photosensitizing Agents / pharmacology*
  • Silicon Dioxide / chemistry
  • Silver / chemistry*
  • Silver / pharmacology*
  • Singlet Oxygen / metabolism*
  • Staphylococcus aureus / drug effects
  • Staphylococcus aureus / metabolism
  • Staphylococcus aureus / physiology
  • Staphylococcus aureus / radiation effects

Substances

  • Photosensitizing Agents
  • Singlet Oxygen
  • Silver
  • Silicon Dioxide