HA‐coated MSNs loaded with DOX were also reported by Zhang et al. They grafted the biotin–HA on desthiobiotin decorated MSNs via a streptavidin‐mediated cross‐linkage, which prevented the DOX release from the pores of the MSNs.217 Once the MSN–HA/DOX was specifically taken up by CD44‐positive cancer cells by receptor‐mediated endocytosis, DOX was released from the pore of MSN by competitive binding of cytoplasmic biotin and desthiobiotin to streptavidin. This evidence concerns the gene CD44 and cancer.