Extended Data Fig. 3: Raman signal intensities of BBT aggregates and BBT NPs.
From: Self-stacked small molecules for ultrasensitive, substrate-free Raman imaging in vivo
a, Raman spectra of BBT aggregates (10 μM) in water/THF mixture (95:5, v/v) and BBT NPs (10 μM of BBT) with a BBT/DSPE-PEG ratio of 5:1 (mol/mol) in water, respectively. b, The Raman scattering cross-sections for per molecule in (a). c, Transmission electron micrographs of 42 nm-BBT NPs. Scale bar, 100 nm. Image shown is representative of n = 3 independent replicates of experiments with similar results. d,e, Raman spectra of (d), and Raman scattering cross-sections (e) in BBT NPs (42 nm v.s. 70 nm in average diameters) with the same BBT/DSPE-PEG (5:1, mol/mol) ratio. Raman scattering cross-sections of BBT were calculated by measuring the Raman peak at 894 cm−1. f, Overview of the molecular docking of BBT (green) binding to HSA (PDB code: 6wuw). The orange indicates a high electrostatic energy. Total score, 8.33. g, Active pocket. h, Functional residue (Lys190, magenta) of HSA interacting with BBT (green). Yellow dashed line, hydrogen bond between HSA and BBT. Two twisted dihedral angles of BBT, 69° and 20°, respectively. i, Raman spectra of BBT (10 uM), the mixture of BBT and HSA (BBT/HSA, 1:50 mol:mol, 10 uM of BBT), and the mixture of BBT NPs and HSA (BBT NPS/HSA, 1:50 mol:mol, 10 uM of BBT), respectively. j, Raman signal-to-noise (S/N) ratio at 894 cm−1 in (i). Raman measurement was carried out with an 830-nm laser excitation, a 5 × objective, a laser power of 62.6 mW, acquisition time of 1 s, and one time accumulation. The cross-section values of BBT NPs were calculated by the Raman peak at 894 cm−1 excited at 830 nm, while using the methanol C-O stretch at 1,020 cm−1 as the internal reference (b,e). n = 3 independent samples (b,e,j). Data are presented as the mean ± s.d. (b,e,j).
