Bimetallic nanoadjuvants for cancer vaccines

Adjuvants are substances used in vaccines to boost antigen-specific immune responses. Aluminum salts (alum) were the first adjuvant approved for human use. Unfortunately, they mainly induce antibody responses and are ineffective at eliciting strong T cell immunity, limiting their use in cancer vaccines. Recent advances reveal the mechanisms of various metal ions in modulating immune signaling. By integrating the synergistic immunomodulation of metal ion pairings with nanotechnology, bimetallic nanoadjuvants (BMNAs) are revolutionizing cancer vaccine. This approach overcomes the limitation of conventional single metal adjuvants by enabling multiplexed immune activation, leading to robust T cell responses for tumor control. This review highlights the immunological mechanisms of metal ions, the rationale behind their pairing in BMNAs, and current challenges for clinical translation.