Fig. 3

Hyperspectral imaging of Pd²⁺ loaded PRs before and after reduction. a Schematic overview of hyperspectral darkfield imaging set-up with representation CCD images for λ = 550, 600 and 650 nm. Images are magnified sub-sections of a larger field of view (scale bar = 20 μm). The spectrum of the circled scatterer is shown in (c). b Plot of the plasmon resonance after Pd²⁺ reduction (λ_final) as a function of resonance wavelength before Pd²⁺ reduction (λ_initial) for 1031 individual PRs with 15 DNA/NP (blue). λ_initial and λ_final for control PRs (identical treatment but without Pd²⁺) and NP monomers are included in green and yellow, respectively. The inset contains the distribution of λ_final. c Exemplary hyperspectral data for an individual PR with 15 DNA/NP whose plasmon resonance blue-shifts upon Pd NP formation. d Plot of the plasmon resonance after Pd²⁺ reduction (λ_final) as function of resonance wavelength before Pd²⁺ reduction (λ_initial) for 1056 individual PRs with 30 DNA/NP