In recent years,exosome has attracted extensive attention of researchers.Result from the studies found that it is related to tumor metastasis,cell to cell communication and protein exchange.Especially in the field of tumor metastasis,exosome secreted from cancer cells has a organ specificity which leads to majority of exosomes reaching to a certain organ,and then result to early response of tumor metastasis of the certain organ.To overcome this problem,we designed a DNA aptamer modified mesoporous silica nanoparticles(MSN-AP)that can specifically capture the exosomes in cancer patients blood to prevent the cancer metastasis caused by exosomes.