Fig. 2. Preparations and characterizations of drug-loaded nanoparticles. (a) and (b) UV-vis spectra of free HMME, free DOX, HM, H-HM@BSA, and DH-HM@BSA. (c) Particle sizes and zeta potentials of HM, DH-HM and DH-HM@BSA during the sequential preparing process. (d) LCs and EEs of HMME in H-HM@BSA at various feed weight ratios of drugs to MnO₂. (e) EEs of HMME and DOX in H-HM@BSA or DH-HM@BSA at various feed weight ratios of drugs to MnO₂. (f) Stabilities of DH-HM and DH-HM@BSA in PBS and FBS reflected by changes in particle size. The date are expressed as means ± standard deviation (SD) (n = 3). (***p < 0.001, **p < 0.01, and *p < 0.05).