Resonant energy transfer and trace-level sensing using branched Ag-rod-supported carbon dots

Abstract

We report on the resonant energy transfer in branched Ag rod-supported carbon dots (C-dots) and its applications for the trace-level sensing of highly reactive oxygen species and organic pollutants based on surface plasmon enhanced energy transfer (SPEET) and surface enhanced Raman spectroscopy (SERS). The branched morphology of Ag is found to significantly enhance visible light absorption and thus increases the spectral overlap with C-dot emission. In addition, branched morphology results in the formation of a large number of plasmonic hotspots and efficient propagation of plasmons through the interconnections, as also supported by finite-difference time-domain simulations. Branched Ag-rod—C-dot composite is found to be able to detect 0.02 µM of hydrogen peroxide based on SPEET. The efficient transfer of electrons from C-dots to the Ag rod enhances the SERS efficiency of Ag resulting in an enhancement factor of the order of 108 and enables the composite to detect 10−10 M of the organic pollutant Rhodamine 6G.

Metal nanoparticles/carbon dots nanocomposites for SERS devices: trends and perspectives

“…In general, the final nanocomposite is composed by metal nanoparticles decorated with carbon dots (see Fig. 4a [32]] and b [56]) in which the synthesis of silver nanorods and the catalytic activity of graphene layers on the production of nanostructures are respectively explored.…”

“…To circumvent these limitations, heteroatom-based structures have been considered a promising strategy to reach superior performance in terms of EF value. Based on this strategy, it is reported values of 10 7 for N-doped carbon dots-Au@AgNPs core-shell structures [69], while enhancement factor in order of 10 8 is observed for branched silver-supported carbon dots [32] and EF values in order of 10 6 -10 7 for systems composed by freestanding Si nanowires decorated with Au/graphene nanoparticles that favor the creation of "multiple hot spots" [70]. These results confirm that improved SERS response for carbon dots-based systems depends on the combination of electromagnetic and chemical mechanisms [70] that can be explored from noble metal arrays, porous substrates and by the interaction of these structures with substrates, allowing the formation of hot spots at different scales and levels.…”

“…A different combination of chemical compounds (such as graphene oxide nanoribbons, graphene oxide, Na-doped carbon quantum dots, and N-doped carbon quantum dots) has been considered as catalysts for nanoparticles synthesis [30]. The adequate interaction of carbon dots and metal nanoparticles in composites takes place from an efficient coupling between plasmons from metal nanoparticle-surface and excitons from carbon dots [31,32] which can also act as electron donors or acceptors to species incorporated into composites. This process is defined as surface plasmon-enhanced energy [11].…”

“…For this, strong coupling between the plasmons in the metallic nanoparticles and the excitons in carbon dots is required from the overlap between the absorption band of metal nanoparticles and the emission of carbon dots. It has been pointed out that the production of broad-band absorption-based systems (such as observed for silver nanorods) [32] leads to a better coupling, which in turn depends on the morphology of the resulting metal nanoparticles. On the other hand, the presence of hot spots is favored by the rich distribution of nanoscale gaps as observed in nanoscale edges and on the tip of the nanoparticles [34] as observed for wire-shaped copper nanostructures in composites with carbon dots [30].…”

Au nano-urchins enabled localized surface plasmon resonance sensing of beta amyloid fibrillation

“…20,21 Recently, metal nanoparticles have become extremely signicant in biosensing research owing to the generation of surface plasmon resonances (SPR). [22][23][24][25][26] Due to the high sensitivity of SPR towards local environmental changes, it serves as a feasible candidate for biosensing and imaging applications. 27,28 Apart from high sensitivity, SPR based sensing provides real-time and label-free sensing of biomolecules.…”