Scheme 1

Active transport of Ful-Fus@rMSN-EuGd through the fucoidan targeting and binding to the overexpressed tumor cell receptor (P-selectin) and the H⁺ ion in low pH intracellular environment will dissociation the interaction of fucoidan sulfate between metal–ligand complex cause gatekeeper decompose and the small molecular fucoidan as anticancer drug release toward the cancer cell