2 research outputs found
Accelerating Gold Nanorod Synthesis with Nanomolar Concentrations of Poly(vinylpyrrolidone)
A novel
modification for the seedless synthesis of gold nanorods
(AuNRs) has been developed. Nanomolar concentrations of 10 kDa polyÂ(vinylpyrrolidone)
(PVP) can be introduced to a growth solution containing 25, 50, or
100 mM cetyltrimethylammonium bromide (CTAB) to significantly reduce
the dimensions of AuNRs. We found that PVP accelerates the growth
rate of AuNRs by more than two times that of nanorods grown in 50
and 100 mM CTAB solutions. Additionally, there is a time-dependent
effect of adding PVP to the nanorod growth solution that can be utilized
to tune their aspect ratio. Because the concentration of PVP is far
below the concentration of HAuCl<sub>4</sub> in the reaction mixture,
PVP primarily functions not as a reducing agent, but as a capping
or templating ligand to stabilize the growing nanorods. Our reproducible
protocol enables the synthesis of AuNRs in high yield with tunable
sizes: 45 × 6.7, 28 × 5.5, and 12 × 4.5 nm for 100,
50, and 25 mM CTAB, respectively. We estimated the number of PVP chains
per nanorod in growth solutions to be around 30, which suggests that
the effect on the aspect ratio is caused by a direct interaction between
the AuNR surface and the PVP
Optimization of Spectral and Spatial Conditions to Improve Super-Resolution Imaging of Plasmonic Nanoparticles
Interactions
between fluorophores and plasmonic nanoparticles modify
the fluorescence intensity, shape, and position of the observed emission
pattern, thus inhibiting efforts to optically super-resolve plasmonic
nanoparticles. Herein, we investigate the accuracy of localizing dye
fluorescence as a function of the spectral and spatial separations
between fluorophores (Alexa 647) and gold nanorods (NRs). The distance
at which Alexa 647 interacts with NRs is varied by layer-by-layer
polyelectrolyte deposition while the spectral separation is tuned
by using NRs with varying localized surface plasmon resonance (LSPR)
maxima. For resonantly coupled Alexa 647 and NRs, emission to the
far field through the NR plasmon is highly prominent, resulting in
underestimation of NR sizes. However, we demonstrate that it is possible
to improve the accuracy of the emission localization when both the
spectral and spatial separations between Alexa 647 and the LSPR are
optimized