Introduction: A major challenge for successful cancer chemotherapy is achieving specific drug accumulation at the tumor site. Due to the lack of specification and solubility of drug molecules, patients must take large doses to obtain the therapeutic effect needed to treat the disease. The development of smart Nano carrier-based drug delivery systems, also known as Smart Drug Delivery Systems, has resulted from the nonspecific distribution and uncontrollable release of drugs in conventional drug delivery systems (CDDSs). Mesoporous silica (MSNs) has emerged as a promising candidate that can overcome these problems and produce effects in a controllable and sustainable manner. Due to their unique structure, Mesoporous silica nanoparticles ensure the controlled release and target drug delivery. At the same time, they were preserving chemical stability, surface functionality, and biocompatibility. As we know, Aptamers have received a lot of attention in targeted drug delivery. For this aim, we synthesized EpCAM aptamer which is an ideal CRC biomarker in active targeting. Method: Initially, the colorectal anticancer drug, oxaliplatin, was loaded in mesoporous silica nanoparticles (MSN), and the release of oxaliplatin at the physiological PH was blocked via the gold gatekeeper. Polyethylene glycol has been used to increase the biocompatibility of nanoparticles in blood circulation. At the end of the synthesis, EpCAM aptamer was used for selective delivery of oxaliplatin drug to colorectal cells (HT-29). The in vitro tests performed include cellular internalization, MTT assay, and evaluation of the cell death mechanism, and in vivo tests examined for the tumor inhibitory effect in female C57BL/6 mice. Result: The results have shown that the targeted nanocarriers containing the aptamer have high cytotoxicity and cellular uptake in colorectal cancer cells (HT-29) compared to the EpCAM-negative CHO cells. Also, the in vivo tests in the human-mouse model have shown that the targeted nanocarrier can increase OXA accumulation in the tumor site and reduce tumor growth compared to the control and non-targeted nanocarrier. Conclusion: A targeted nanocarrier platform based on MSNs, which can effectively deliver OXA to human CRC cells, can reduce side effects, and increase anticancer effects.

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