Monitoring the Stimulated Uncapping Process of Gold-Capped Mesoporous Silica Nanoparticles

Abstract

To establish a new method for tracking the interaction of nanoparticles with chemical cleaving agents, we exploited the optical effects caused by attaching 5–10 nm gold nanoparticles with molecular linkers to large mesoporous silica nanoparticles (MSN). At low levels of gold loading onto MSN, the optical spectra resemble colloidal suspensions of gold. As the gold is removed, by cleaving agents, the MSN revert to the optical spectra typical of bare silica. Time-lapse images of gold-capped MSN stationed in microchannels reveal that the rate of gold release is dependent on the concentration of the cleaving agent. The uncapping process was also monitored successfully for MSN endocytosed by A549 cancer cells, which produce the cleaving agent glutathione. These experiments demonstrate that the optical properties of MSN can be used to directly monitor cleaving kinetics, even in complex cellular settings.

An optimized mesoporous silica nanosphere-based carrier system with chemically removable Au nanoparticle caps for redox-stimulated and targeted drug delivery

“…Note that simple physical mixing of Au NPs and MSN-PDEA would not result in such homogeneous coating of the Au NPs, but only a few loosely attached Au NPs on the surface of MSNs (SI figure 2(b)). This is consistent with a similar study and proves the successful covalent conjugation of Au NPs on MSNs [41].…”

Analytical Methods for Monitoring the Degradation of Plasmonic Nanoparticles in Solution: An Instrumental Analysis Laboratory Exercise

“…The oscillation may be dipolar or higher-order in nature, , but it is maintained as long as the nanoparticle is exposed to the proper radiation. When a nanoparticle undergoes LSPR, it exhibits vastly improved absorption and scattering of light, to the point that low concentrations of the particles can be monitored with a UV–vis spectrophotometer and in some cases individual particles can be detected with light microscopy. , Silver and gold are the two most popular metals for making plasmonic nanoparticles for many reasons: stability, signal intensity, ease of synthesis, and resonance in the visible portion of the electromagnetic spectrum.…”

“…In the case of plasmonic nanoparticles, UV–vis spectrophotometry is a popular method for performing basic quality control, ,, and it can be used to monitor the condition of the nanoparticles as they age. A shift in the LSPR-associated absorbance peak to longer (or shorter) wavelengths suggests that the nanoparticles are growing (or shrinking) in size.…”