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Photodynamic therapy (PDT) is typically harmless without light, tumor site treatment can be precisely targeted by selective illumination, limiting damage to surrounding healthy tissues. However, there are some difficulties with the use of photosensitizers(PSs), such as water-insolubility and low tumor-selectivity, which often limit its broader clinical applications in PDT. For overcome of these problems, we have improved their targeting efficiency and solubility through conjugate with target moiety labeled polysaccharides(1-3). During circulation in the blood, nanogel photoactivity may be suppressed by a self-quenching effect between PS molecules grafted to the target moiety labeled biocompatible polymer backbone similar to the fluorescence resonance energy transfer (FRET) effect(4). As the nanogel penetrates tissue and internalizes in cancer cells, photoactivity may be restored due to loss of the FRET effect by cleavage of the target moiety labeled biocompatible polymer backbone and the ester bond in the PS graft through enzymatic attack in the extracellular matrix and cellular compartments such as lysosomes. The target moiety conjugated with biocompatible polymer via DCC- and DMAP-mediated ester formation and dialyzed against distilled water for 2 days using a dialysis membrane. PS conjugate with target moiety labeled biocompatible polymer by the formation of an ester linkage, similar to the method of target moiety/biocompatible polymer conjugation the chemical conjugation was confirmed by 1HNMR spectroscopy and the degree of substitution was determined by UV–vis spectrophotometry. The conjugates was dissolved in 10 mL DMSO and dialyzed against excess deionized water . In 3 days, dialysates were collected and the volume of them was adjusted to 100 mL . The size distribution was measured by DLS and its photocytotoxicity was studied by XTT assay(5). The resulting nanogel are spherical, stable with a average size of 170nm and show self-quenching in aqueous system and have the capacity for tumor tissue targeting for nano-size induced EPR. After accumulated in tumor, the fluorescence signal will enhance gradually by the release of the dye because of broken down of nanogel as the exit of cleavable ester linkage .The irradiation with light of suitable wavelength of the photosensitizing drug uptaken by the cells resulted in generation of singlet oxygen for photodynamic therapy, simultaneity the near-infrared fluorescence molecular imaging can be detected