This cluster of papers focuses on the development and application of nanoparticle-based drug delivery systems, particularly for cancer therapy. It covers topics such as nanocarriers, surface engineering of nanoparticles, magnetic nanoparticles, tumor targeting, polymeric nanoparticles, and the enhanced permeability and retention (EPR) effect. The research explores the synthesis, functionalization, and biomedical applications of various types of nanoparticles for drug delivery.