Building off earlier work relating to mineral coatings, UW-Madison researchers have extended this work to FeOs to generate mineral-coated FeO microparticles (FeO MCMs). The FeO MCMs are created using a well-established protocol that results in the formation of a porous calcium phosphate coating on the surface of the magnetic FeO microparticles. The refined coating process allows for control over thickness and porosity – characteristics affecting electrostatic properties and loading. The inventors have shown that FeO MCMs increase inflammatory cytokine expression by macrophages, through what they hypothesize is an iron-based Fenton reaction resulting in the generation of ROS. Modulating tumor-associated macrophages towards an M1 phenotype is an attractive strategy for increasing immune presence within (e.g., making them hot) and synergizing with other immunotherapies. They have also shown inhibition of tumor cell growth through incubation with FeO MCMs, potentially due to iron toxicity or ferroptosis.