Ultrasmall Platinum Nanoparticles for Radiation‐Enhanced Cancer Therapy

Despite decades of intense research, cancer remains a major global health challenge, with a clear need for new and more efficient therapies. Among emerging approaches, high atomic number (Z) nanomaterials capable of modulating the interaction between radiation and matter have attracted growing interest as radiotherapy enhancers. In this work, ultra‐small Platinum‐based nanoparticles with a metallic core diameter of 2–3 nm were synthesized from H 2 PtCl 6 using polyvinylpyrrolidone as stabilizer. This nanomaterial exhibits low acute toxicity, catalase‐like activity and enhances DNA damage under pre‐clinical X‐ray irradiation, increasing the antitumoral effect of X‐ray alone. In vitro and in vivo studies, including intratumoral and intravenous administration, demonstrate improved tumor control and prolonged survival without detectable systemic toxicity under the tested conditions, establishing ultra‐small Pt‐nanoparticles as efficient materials for radiotherapy enhancement.