Heterogeneous kinetics in the functionalization of single plasmonic nanoparticles
Matej Horacek, Rachel E. Armstrong, and Peter Zijlstra
The functionalization of gold nanoparticles with DNA has been studied extensively in solution, however these ensemble measurements do not reveal particle-to-particle differences. Here we study the functionalization of gold nanorods with thiolated single stranded DNA (ssDNA) at the single-particle level. We exploit the sensitivity of the plasmon resonance to the local refractive index to study the functionalization in real-time using single-particle spectroscopy. We find particle-to-particle variations of the plasmon shift that are attributed to the particle size distribution and variations in ssDNA coverage. We find that the ssDNA coverage varies by ~10% from particle-to-particle, beyond the expected variation due to Poisson statistics. Surprisingly, we find binding rates that differ from particle-to-particle by an order of magnitude, even though the buffer conditions are identical. We ascribe this heterogeneity to a distribution of activation energies caused by particle-to-particle variations in effective surface charge. These results yield insight into the kinetics of biofunctionalization at the single particle level, and highlight that significant kinetic heterogeneity has to be taken into account in applications of functional particles. The presented methodology is easily extended to any nanoparticle coating and can be used to optimize functionalization protocols.
Peter will present the group’s most recent results at the Gordon Research Conference in Hong Kong on Plasmonically Powered Processes! For the conference’s full program see https://www.grc.org/plasmonically-powered-processes-conference/2019/.
We are happy to announce that we are currently hiring 3 scientists to join our team! We are constantly seeking to use our fantastic molecular plasmonics tools to answer intriguing...
A great article has been posted on the TU/e science webpage about the use of super-resolution microscopy to quantify nanoparticles. This article describes our research in the Marie Curie ITN...