The aptamer-Dox conjugate prevents the nonspecific uptake of Dox and decreases cellular toxicity to the non-target cells. Furthermore, the in vivo experiment showed better tumor inhibition by the TLS11a-GC-Dox group compared to all other control groups, indicating the successful delivery of Dox by the modified aptamer. This targeting specificity assured a higher local Dox concentration in the tumor. In addition, aptamer-Dox conjugates are smaller than antibodybased drug delivery systemsand some other delivery system, allowing faster penetration and fewer immunoreactions. We anticipate that the newly designed aptamer-Dox conjugation platform, which is based on the intercalation of anthracyclines within the bases of aptamers, may be utilized in distinct ways to develop novel targeted therapeutic modalities for more effective 1-Tigloyltrichilinin cancer chemotherapy. Oral squamous cell carcinoma is one of the most common and lethal head and neck malignancies in Taiwan and worldwide. OSCC is a disease that is difficult to treat because of the diverse treatment strategies available and the variable natural behavior of the cancer. Local invasion and frequent regional lymph node metastases, together with relative resistance to chemotherapeutic drugs, lead to an unpredictable outcome. Despite increased experience in surgical technology and adjuvant treatments, the overall prognoses of OSCC remain unimproved, resulting in the urgent need of a novel strategy for OSCC treatment. Substantial evidences from recent studies show that solid tumors contain a subpopulation of cancer stem cells. It is well known that CSCs play an important role in tumor initiation, progression, metastasis, and therapeutic resistance. However, the putative CSCs from OSCC have not been well characterized. It is hypothesized that CSCs possess several characteristics that make them resistant to conventional chemoand radiotherapy, including high expression of drug transporters, relative cell-cycle quiescence, high function of DNA repair machinery, and resistance to apoptosis. The identification and characterization of CSCs from OSCC are crucial for facilitating the monitoring, treatment, and prevention of the disease. The isolation of CSCs from cancer cells has been achieved successfully via the use of different techniques. The isolation of CSCs is performed using flow cytometry based on the expression of specific cell surface markers, such as CD133, CD44 and ALDH1, by CSCs. Because of the therapeutic resistance of CSCs, sorting the side populations of cancer cells via intracellular Hoechst 33342 exclusion or selecting chemotherapeutic-drug-resistant cells has also been used for the identification and characterization of CSCs. Concurrent studies confirmed that the sphere culture Oxprenolol hydrochloride system is as efficient in separating CSCs from many solid tumors or cancer cells lines. These studies have suggested that CSCs can be enriched in spheres when these are cultured in serum-free medium supplemented with adequate mitogens, such as the basic fibroblast growth factor and epidermal growth factor. However, the derivation of CSCs from solid tumors and cancer cell lines cultured in serum-free medium supplemented with bFGF and EGF is a time-consuming process and 2�C6 weeks are needed for sphere formation. Furthermore, the selected growth factors, such as the platelet-derived growth factor, bFGF, and EGF, are costly and ineffective. To overcome these drawbacks and limitations, we used a purpose-designed nonadhesive sphere culture system to identify and enrich CSCs from established human OSCC cell lines, and to characterize their CSC properties further using phenotypic/genotypic characterization.