Active tumor targeting drug delivery is a tumor treatment strategy that improves tumor-cell-specific uptake of drug molecules with enhanced therapeutic efficacy.This strategy entails specific recognition of the surface marker of a tumor cell by a ligand either directly conjugated to the drag molecule.However, current cancer therapies are limited by side effects resulting from a lack of tumor cell selectivity.Accordingly, there is great interest in molecules that can distinguish between healthy and cancerous tissue.A few such compounds, typically polypeptides or polysaccharides, have been described;however, their sizes can limit their pharmacologic utility.The prospects for successful utilization in classic therapeutic strategies would increase dramatically if the sizes of these tumor-targeting molecules could be reduced.For example, smaller compounds tend to be less immunogenic, easier and less expensive to prepare,and more readily amenable to use in prodrug conjugates or as diagnostic agents.In our recent results, we found that the BLM disaccharide or monosaccharide is both necessary and sufficient for tumor cell targeting, a finding with obvious implications for the design of novel tumor imaging and the rapeutic agents, The finding that the BLM disaccharide (or simply the 3-O-carbamoyimaunose moiety of the disacchadde) is bound and internalized by tumor cells thus provides a unique opportunity for the selective delivery of cytotoxic agents to tumor cells.The ability of these species to deliver attached molecular cargoes has been demonstrated both by analysis of the cellular internalization of attached dyes and cellular delivery of the clinically used cytotoxic agent methotrexate.Multiple drug resistance (MDR) is a major challenge for cancer chemotherapy.Different mechanisms, including the increased efflux of chemotherapeutic agent from cancer cells, blocked apoptosis, decreased drug influx, and altered cell cycle regulation, can lead to MDRs Targeted delivery of anticancer drugs to mitochondria.The energy factory to sustain the cell viability, has been considered as a great promising strategy to prevent or inhibit the MDR effect of cancer ceils.In our previous reports, we have demonstrated that certain monosaccharide molecule (MM) could recognize cancer cells and mitochondria could be targeted by specific polypeptide sequence.A MM-MTS-DOX (MTS, mitochondria targeted signal) multifunctional drug delivery can actively target cancer cell membrane and mitochondria based on the above hypothesis.This system is able to targeted deliver DOX to breast cancer cells, cure cancer cells and decrease the cytotoxicity and side effects of DOX.Therefore, this project will bind MM ligand to DOX functionalized with MTS to fabricate MM-MTS-DOX targeted drug delivery system.Both in vivo and in vitro experiments will be performed to test and verify the capability of this targeted drug delivery system for delivering DOX to the mitochondria of cancer ceils.With this system,we desire to regulate the expression of related genes by targeting mitochondria and enhance killing capacity of DOX for drug-resistant cancer cells and inhibit cell cycle.Thus the targeted delivery system will increase therapeutic efficacy and overcome MDR.Furthermore, this novel drug delivery system targeting mitochondria will provide new insights for targeted cancer therapy.