Surface Charge-Dependent Targeting and Penetration of Magnetic Nanoparticles into Eggs and Adult Worms of Schistosoma japonicum

Background/Objectives: The precise elimination of Schistosoma japonicum eggs within host tissues poses a significant therapeutic obstacle due to the ineffectiveness of existing drugs in penetrating the eggs’ protective shields. This investigation sought to create a surface-modified magnetic nanoparticle (MNP) framework to surmount this hurdle and realize targeted theranostics for combating schistosomiasis. Methods: Fe3O4 MNPs, MNP-NH2, and MNP-COOH were synthesized and characterized before systematically studying their interactions with parasites. The intrinsic autofluorescence of eggs and adult worms served as an optical background for the investigation. In vitro co-incubation assays, confocal microscopy, and Prussian blue staining were utilized to quantify both adsorption and internalization. The in vivo efficacy was assessed in a Schistosoma japonicum murine model following tail vein injection. Results: A pronounced surface chemistry-dependent interaction was noted. Fe3O4 MNP and MNP-NH2 displayed remarkable adsorption and effective internalization into eggs in vitro, while MNP-COOH exhibited limited uptake. This varying effectiveness was similarly observed in vivo, with Fe3O4 MNP and MNP-NH2 predominantly gathering in hepatic granulomas and effectively infiltrating deposited eggs. Within adult worms, Fe3O4 MNP and MNP-COOH exhibited distribution on the tegument and within adult worms. Conclusions: We developed a functional MNP platform in which surface charge governs parasiticidal targeting. Among the candidates investigated, MNP-NH2 proved to be the most efficient for egg-targeted theranostics. This study introduces an innovative nanotechnology-based approach for accurate diagnosis and treatment of schistosomiasis by specifically tackling the challenge of impermeable eggs.