Fig. 3
From: Dye-doped silica nanoparticles: synthesis, surface chemistry and bioapplications
(a, b adapted from Battistelli et al. (2016); c, d adapted from Wang and Tan (2006))
Optimising dye loading is crucial to achieving maximal NP brightness. a (left) A low number, n, of fluorophores present in the NP maximises quantum yield, Ï•, but NP brightness, B, is low. a (right) A high concentration of fluorophores can lead to FRET/self-quenching and result in a low brightness NP. The optimal loading window in shown in blue. b Left: ideally, self-quenching and FRET can be minimised by controlling dye distribution or, b (right) using molecules with large Stokes shift such their proximity is not problematic. c Absorbance spectrum of silica NPs doped with different FITC:Rhodamine6G:ROX ratios. d Different dye-doping ratios could generate silica NPs with different fluorescent signatures