Fig. 1

Characterization of PLNP^Cu. a, b TEM images of PLNP^Cu at pH 7.4. c TEM images of PLNP^Cu at pH 6.5. d DLS of PLNP^Cu at pH 7.4. e The pH-triggered charge rebound behavior of PLNP^Cu (n = 3). f Maintenance of size stability of PLNP^Cu in PBS and PBS with 5% FBS (at pH 7.4) (n = 3). g LOX loading capacities on LNP and LNP^Cu respectively (n = 3). h Cumulative release of LOX from PLNP^Cu in PBS at pH 7.4 and pH 6.5 (n = 3). i Hemolysis rate of PLNP^Cu at different PEI concentrations (n = 3). Results were expressed as mean ± SD. The significant difference was calculated via two-tailed t-test analysis (g). (NS represented not significant, *p < 0.05, **p < 0.01, ***p < 0.001)