The PEI-AuNRs/siRNA complex formed by siRNA adsorption on AuNRs functionalized on the surface of polyethyleneimine (PEI) can effectively deliver siRNA to breast cancer cells, and siRNA can resist pyruvate kinase M2 type (PKM2) to achieve gene silencing, significantly reducing the viability of breast cancer cells [113]. Here, PKM is linked to breast cancer.