Fig. 2. (a) HRTEM image, (b) size distribution and (c) zeta potential of Ru–PEI@SiO2 nanospheres. (d) SEM image of the Ru–PEI@SiO2/Au NT/PDMS sensor. (e) ECL spectra of bare Au NTs/PDMS (blue), Ru@SiO2/Au NTs/PDMS (dark blue), Ru@SiO2@PEI/Au NTs/PDMS (green) and HLNs/Au NTs/PDMS (red) each in 600 μL of 0.1 M PBS (pH 7.4). (f) Fluorescence spectrum of Ru–PEI@SiO2 nanospheres (blue) in methanol and ECL spectrum of Ru–PEI@SiO2/Au NTs (red) in 0.1 M PBS (pH 7.4) through a series of optical filters: 500 nm, 525 nm, 550 nm, 575 nm, 600 nm, 625 nm, 650 nm, 675 nm, and 700 nm.
