A　controllable　length　of　inorganic　nanotubes　as　a　drug　delivery　system　is　crucial　to　understanding　internalization　mechanisms　and　designing　new　biomedical　applications.　In　this　study,　silica　nanotubes　(SiNTs)　with　controlled　length　ranging　from　several　hundred　nanometers　to　several　micrometers　were　firstly　fabricated　via　a　facile　and　effective　acid-degradation　collagen　template　route　and　then　functionalized　with　chitosan　(ChSiNTs)　to　deliver　immunostimulatory　cytosine-phosphodiester-guanine　oligodeoxynucleotides　(CpG　ODNs).　It　was　found　that　the　length　of　SiNTs　could　be　well　controlled　through　the　adjustment　of　the　acid-treatment　temperature.　Cytotoxic　assessment　indicated　that　SiNTs　exhibited　good　biocompatibility　when　separately　incubated　with　four　types　of　cell　lines:　293XL-hTLR9,　A549,　NIH3T3,　and　C2C12.　The　cellular　uptake　of　SiNTs　was　strongly　affected　by　their　length　and　cell　type.　A　decrease　in　the　length　led　to　an　increase　in　the　cellular　uptake　of　SiNTs,　while　a　significantly　higher　cellular　uptake　by　C2C12　cells　was　observed　in　comparison　with　A549　and　NIH3T3　cells.　An　immunochemical　assay　revealed　that　SiNTs　were　located　in　the　endolysosomes　after　cellular　internalization.　ChSiNTs　were　positive　and　well　complexed　with　negative　CpG　ODNs　to　produce　a　ChSiNT/CpG　ODN　complex　(CpG-ChSiNT)　via　electric　force.　ChSiNTs　were　located　in　the　endolysosomes　after　internalization　and　enhanced　the　cellular　uptake　of　CpG-ODNs.　CpG　ODNs　could　be　released　from　CpG-ChSiNTs　in　a　sustained　way　and　specifically　recognized　by　the　TLR9　receptor　in　293XL-hTLR9　cells.　The　amount　of　interleukin-6　cytokine　stimulated　by　CpG-ChSiNT　against　peripheral　blood　mononuclear　cells　was　higher　than　that　by　free　CpG　ODNs　and　ChSiNTs　significantly　enhanced　the　immunostimulatory　response　of　CpG　ODNs.　©　The　Royal　Society　of　Chemistry　2015.