Aptamers consisting of a single stranded nucleic acids having 100 nucleotides or less that specifically binds to tumor initiating cancer cells are described. The aptamers can be identified by screening a large pool of randomly generated aptamers to obtain a discrete set of aptamers that specifically bind to tumor initiating cancer cells, such as those found in brain cancer or glioblastoma. The aptamers can also be linked or complexed with anticancer agents or imaging agents for use in therapy or diagnosis.
