Disclosed herein is a use of Fe3-δO4 nanoparticle in inhibiting the spore germination of Clostridium difficile. The Fe3-δO4 nanoparticle specifically targets the spores of Clostridium difficile spores by damaging and breaking the intact structure of the Clostridium difficile spores. Further, the Fe3-δO4 nanoparticle possesses superior sporicidal activity, as compared to other known bactericidal nanoparticles. Therefore, the Fe3-δO4 nanoparticle of the disclosure is useful as a bactericide or more specifically, a sporicide to treat Clostridium difficile infection for its superior sporicidal activity.