FRET on Surface of Silica Nanoparticle: Effect of Chromophore Concentration on Dynamics and Efficiency

Abstract

Forster resonance energy transfer (FRET) has been studied between fluorescein (donor, D) and rhodamine B (acceptor, A) bound covalently to the surface of silica nanoparticle (SNP-dye). This is a part of an ongoing effort toward development of light harvesting nanoantennae. The role of the D:A ratio and the total chromophore content on the efficiency of FRET has been investigated. At low number density (ca. 75 ± 15 dye molecules/particle) efficiency is dependent on the D:A ratio. It appears that the distribution of the dyes on the surface is inhomogeneous and that FRET occurs only between D and A molecules in very close proximity. The effect of self-quenching of the donor is not very significant for this number density. At higher number densities (ca. 700−1100 dye molecules/particle), a prominent rise in the acceptor emission is observed, perhaps indicating a more homogeneous distribution of the dye molecules, and D emission is quenched completely. However, D−D quenching is an issue here. So, it appears that the lower number density is a more favorable condition for FRET in these systems.

Photochemistry and Photophysics in Silica-Based Materials: Ultrafast and Single Molecule Spectroscopy Observation

“…In a system containing fluorescein (D) and RhB (A) in silica materials (Scheme 5), two types of dye-silica nanoconjugates have been designed and examined: one based on silica nanoshells (SNS-dye) and another on silica nanoparticles (SNP-dye). 406,407 In both nanosystems, the concentration of donor molecules affects the FRET efficiency and dynamics. While the amount of acceptors was kept constant, the D:A concentrations ratio changed from 0.5 to 3 in SNS-dye and from 0.5 to 4 in SNP-dye systems.…”

Competition between Photoinduced Electron Transfer and Resonance Energy Transfer in an Example of Substituted Cytochrome c–Quantum Dot Systems

“…Also, the less-than-optimal stoichiometry between donors and acceptors might have influenced measurements, as shown with fluorescein and rhodamine on the surface of silica nanoparticles. 53 The same situation might be observed for free donors or acceptors in solution. 54 A weak or no increase in the acceptor lifetime was observed for some FRET pairs, as for Alexa488–Alexa568 double-labeled apoflavodoxin.…”

“…We also experienced signal contamination due to the coexcitation of a donor and an acceptor, as a result of limitations in available laser sets. Also, the less-than-optimal stoichiometry between donors and acceptors might have influenced measurements, as shown with fluorescein and rhodamine on the surface of silica nanoparticles . The same situation might be observed for free donors or acceptors in solution .…”

Role of Solvent in Electron‐Phonon Relaxation Dynamics in Core‐Shell Au−SiO2 Nanoparticles

“…[36][37][38][39][40][41] Silica coating not only stabilizes the Au core by hindering aggregation and degradation, but also provides a functionalizable exosurface for grafting organic molecules. [42][43][44] They have been found to augment electrochemiluminescence of quantum dots grafted on them [36] and have found use in design of immunosensors for insulin, [45] in solar energy harvesting [46] and in the increase in efficiency of dye-sensitized solar cells. [47] They have also been found to enhance catalytic efficiency of palladium nanoparticles due to efficient energy transfer from Au to palladium.…”