Targeted　delivery　of　anticancer　agents　by　functional　nanoparticles　is　an　attractive　strategy　to　increase　their　therapeutic　efficacy　while　reducing　toxicity.　In　this　work,　doxorubicin　(DOX)-loaded　mesoporous　silica　nanoparticles　(MSNs)　were　modified　with　aptamer　(Ap)　against　the　epithelial　cell　adhesion　molecule　(EpCAM)　for　targeted　delivery　of　DOX　to　colon　cancer　cells.　These　nanoparticles　(Ap-MSN-DOX)　were　characterized　by　particle　size,　zeta　potential,　aptamer　conjugation　efficiency,　drug　encapsulation　efficiency,　and　drug　release　properties.　The　in　vitro　cell　recognition,　cellular　uptake,　EpCAM　protein　inhibition　efficiency,　and　cytotoxicity　of　Ap-MSN-DOX　were　also　studied.　Results　demonstrated　that　EpCAM　conjugation　increased　binding　of　Ap-MSN-DOX　to　EpCAM　over-expressing　SW620　colon　cancer　cells　but　not　EpCAM-negative　Ramos　cells,　resulting　in　enhanced　cellular　uptake　and　increased　cytotoxicity　of　the　DOX　in　SW620　cells　when　compared　to　non-Ap-modified　nanoparticles　(MSN-DOX).　Additionally,　Ap-MSN-DOX　exhibited　significant　inhibition　effects　on　the　expression　of　EpCAM　on　SW620　cells.　These　results　suggested　that　Ap-MSN-DOX　has　the　potential　for　the　targeted　delivery　of　therapeutic　agents　into　EpCAM　positive　colon　cancer　cells　to　improve　therapeutic　index　while　reducing　side　effects.　©　2015　Elsevier　B.V.