Fig. 5

Targeting modification, cytotoxicity and in vivo pharmacokinetics. a Chemical structure of CYSAYPDSVPMMS peptide. SPPS solid-phase peptide synthesis. b Schematic of the preparation of a RClosed-YSA NP. c Western blot analyses of EphA2 in L02 cells and 4T1 cancer cells. d Cell viability of RClosed-YSA NP-incubated 4T1 cancer cells after 610 nm red light (0.3 W cm⁻²) irradiation for 5 min. Error bars, mean ± s.d. (n = 4). e Cell viabilities of the converted ROpen-YSA NP-loaded and converted ROpen NP-loaded 4T1 cancer cells under white light irradiation (0.25 W cm⁻², 4 min). Error bars, mean ± s.d. (n = 4). *P < 0.05, unpaired Student's t-test (two-tailed). The cells were incubated with RClosed-YSA and RClosed NPs, respectively, followed by exposure to 610 nm red light (0.3 W cm⁻²) for 5 min, to obtain the converted ring-opening NP-loaded cells. In d and e, the concentration is based on DTE-TPECM. f Pharmacokinetics study of ¹²⁵I-labelled RClosed-YSA NPs analysed by scintillation count of ¹²⁵I radioactivity in blood. Error bars, mean ± s.d. (n = 6 rats). Inset displays the schematic of an ¹²⁵I-labelled RClosed-YSA NP. g Biodistribution of ¹²⁵I-labelled RClosed-YSA NPs in various tissues of 4T1 tumour-bearing mice at different time points post-intravenous injection. Error bars, mean ± s.d. (n = 6 mice for each time point)