Reversible photoswitching of dye-doped core–shell nanoparticles

Abstract

We present a simple and versatile mechanism for the reversible photoswitching of dye-doped core-shell nanoparticles. Photochromic dithienylethenes are incorporated into the outer shell, close enough to the dyes entrapped in the core to efficiently quench them by energy transfer when photoconverted with UV light. The emission can be switched back on by irradiation with λ > 450 nm.

A Versatile Strategy for Signal Amplification Based on Core/Shell Silica Nanoparticles

“…Most interestingly, we have very recently demonstrated the possibility of also hosting water-insoluble dyes in the outer shell, which are able to give rise to very efficient energy transfer processes with the molecules hosted in the core. [15] Thanks to the unique structure and properties of these nanoparticles, their application in sensing can be envisaged to involved a new type of transduction mechanism based on the addition of a hydrophobic chemosensor to a water solution of the nanoparticles (Figure 1). It must be underlined, that the requirement related to the hydrophobicity is not a limitation; rather, it makes possible the use of a large series of systems that are usually precluded due to their insolubility in water-based environments.…”

A fluorescent probe for ecstasy

“…These nanoparticles present, together with an organo-silica core and an outer hydrophilic PEG shell, responsible for the stability of their dispersion, an enhanced hydrophobic internal compartment. This is similar to the one that has been already used to host hydrophobic dyes, 10 photo-switches 11 and other chemical sensors 12 for different applications. 13 The use of a confined environment in this case was also conceived to favor the formation of an intramolecular excimer.…”

Reversible Photoswitching of Spiropyran-Conjugated Semiconducting Polymer Dots

“…15–21 Various strategies, including emulsion polymerization, copolymerization, and core-shell embedding, have been used to build a hydrophobic core with a hydrophilic surface. 16,22,23 In those studies, the photochrome, for example spiropyran (SP) or diarylethene molecules, served as photoswitchable quencher: Once it was converted to its colored form by the absorption of ultraviolet (UV) light, it efficiently quenched the emission of its partnering fluorophore.…”