Fig. 3: Characterisation of cis-GdAzo activation upon different radiation sources.
a Absorbance spectra of cis-GdAzo (PSS1 in blue) recorded after GR (0.5 Gy increment in the 0.5-2 Gy range and 1 Gy increment in the 2-8 Gy range). The graph Ln[(A0-Ainf)/(At-Ainf)] by the irradiation dose (0.5-2 Gy range) is plotted on the top-right corner, with A0, Ainf and At the absorbances of PSS1, trans-GdAzo and the mixture at a specific irradiation dose respectively. Linear regression (least-squares method, r2: 0.9521, GraphPad Prism 5.00) were used to determine the activation constant k = (2.1 ± 0.2)*10−1 Gy−1 (triplicate, n = 3 independent experiments, F-value = 258.3, P < 0.0001). b, c Molecular activation of cis-GdAzo and cis-Azo determined by HPLC and reported as the difference of trans-isomer proportion before and after XR (b) and E (c) irradiations (n = 3 independent experiments). Two-way Anova (Bonferroni post-test) was used for statistical analyses (All vs GdAzo GR, t-values = 16.93, 23.90, 30.65, 33.01 and 19.04, 28.43, 32.09, 34.01 for GdAzo NI vs GdAzo GR at doses 2, 5, 10, and 20 Gy upon XR and E respectively). ***P < 0.001. d Radiochemical yields (G-values) of trans-GdAzo determined by HPLC (corrected from thermal back relaxation) upon XR, GR and E irradiations (n = 3 independent experiments). e Molecular activation of cis-GdAzo upon XR, GR and E irradiations determined by HPLC. f Monte Carlo simulation to quantify the energy of secondary electrons emitted by the interaction of the incident primary particle on the Gd atom upon XR, GR and E irradiations. The means ± standard deviations are reported. OD optical density.
