The potential molecular mechanism is: the prepared RNA nanoparticles can enter into the cytoplasm specifically via folic acid receptor mediated endocytosis and inhibit BRCAA1 expression in gastric cancer cells by uploaded BRCAA1 siRNA, resulting in the up-regulation of Rb and Bax, down-regulate the expression of BCl-2, and inducing of gastric cancer cell apoptosis. The gene discussed is BCL2; the disease is gastric cancer.