Preparation of hydrophobically modified carboxylated pullulan nanoparticles for evaluating the effect of hydrophobic substitution on the properties and functions of nanoparticles

We designed three cholesterol-modified carboxylated pullulan (CHSP) polymers modified with different degrees of substitution (DS). Nuclear magnetic resonance (NMR) was used to characterize CHSP polymer and calculate the DS, which were 2.12%, 4.36% and 6.05% for CHSP1, CHSP2 and CHSP3. The particle sizes identified by dynamic light scattering (DLS) were approximately 229.4 nm, 185.1 nm and 178.0 nm.The mitoxantrone (MTO) loadings of three nanoparticles were 5.28%, 6.71% and 7.68%. At pH 6.8, 72 hours later, the drug release rates were 95.42%, 86.88%, and 80.16%. In the weakly acidic environment, the drug release rate was significantly accelerated but still showed three types of nanoparticles and hydrophobic substitution degree-related slow release characteristics. In the cytotoxicity experiments, it was found that the inhibitory effect of the three nanoparticles on hepatoma cells is related to the degree of hydrophobic substitution, and the nanoparticles with the lowest hydrophobic substitution degree have the strongest inhibitory effect.