NIR-Ⅱ Fluorescent Nanochain Probe For Surgical Navigation Of Peritoneal Carcinomatosis

Peritoneal carcinomatosis is the common secondary peritoneal metastases caused by many malignant tumor cells dissemination.To achieve accurate surgical elimination of peritoneal carcinomatosis in vivo,it is essential to clearly define the tumor boundaries and discover hidden microscopic lesions.However,it remains a great challenge to achieve efficient cytoreduction,owing to the poor visual contrast between cancer and normal tissues.Thus,it is greatly significant to develop and improve intraoperative visual methods for surgical treatment of peritoneal metastasis in clinical applications.The NIR-II fluorescence featured with high tissue penetration depth,high spatio-temporal resolution as well as high signal-to-noise ratio provides a powerful mean for image-based accurate surgical navigation of tumors.Based on the unique optical properties of AgzS quantum dots in the NIR-II window（broad-band absorption and narrow-band emission,size-dependent fluorescence emission,anti-photobleaching,etc.）and its high biocompatibility（non-toxic heavy metal elements）,a targeted nanochain probe（APP-Ag₂S-RGD）was successfully prepared by APP-based self-assembly and following chemical crosslinking of Ag₂S QDs and RGD peptide.Benefiting from its flexible geometry and multivalent targeting as well as unique NIR-II fluorescence properties,the APP-Ag₂S-RGD exhibits the unparalleled detection sensitivity during the surgery of cancer peritoneal metastasis.The main contents of this thesis includes the following three parts:1.The synthesis of the targeted NIR-II fluorescence nanochain probe（APP-Ag₂S-RGD）:The amphiphilic peptide APP was self-assembled into nanowire structure;coupling Ag₂S QDs to APP nanowire by chemical cross-linking;the targeted peptide RGD was further modified on the APP nanowire by chemical cross-linking.The targeted nanochain probe APP-Ag₂S-RGD was successfully synthesized and has excellent near-infrared fluorescence characteristics confirmed by the characterization of TEM,Zeta potential and spectroscopy.2.The tumor cell labeling in vitro using the targeted NIR-II fluorescence nanochain probe（APP-Ag₂S-RGD）:The labeling effect of APP-Ag₂S-RGD on tumor cells was examined by observing the near-infrared fluorescence signal of U87-MG cells co-incubated with APP-Ag₂S-RGD.The viability of labeled cells was detected by using Annexin V-FITC/PI kit.The results showed that APP-Ag₂S-RGD can effectively label tumor cells without affecting the activity of U87-MG cells.Furthermore,we verified the specificity of the probes.As expected,the fluorescence intensity of the αvβ3-negative MCF-7 cells was significantly lower than that ofαvβ3-positive U87-MG cells3.The fluorescent-guided intraoperative navigation of peritoneal carcinomatosis with the targeted NIR-II fluorescence nanochain probe（APP-Ag₂S-RGD）:After constructing the mouse model of peritoneal metastasis using U87-MG cells containing firefly luciferase reporter gene（RfLuc）,the nanochain fluorescent probe APP-Ag₂S-RGD was injected intraperitoneally and the near-infrared fluorescence signal was detected in preoperative and intraoperative to detect the targeting effect of APP-Ag₂S-RGD on the tumor in vivo.The combination of near-infrared fluorescence signal and pathological results indicate that under the guidance of near-infrared fluorescence of targeted nanochain APP-Ag₂S-RGD,tumor boundaries can be clearly defined and hidden microscopic lesions can be found,maximally increasing tumor detection rate and accuracy.Conclusion:we have successfully constructed a novel targeted NIR-II fluorescence nanochain probe（APP-Ag₂S-RGD）by self-assembly of amphiphilic peptide（APP）followed with covalent crosslinking of Ag₂S QDs and RGD peptide.This probe exhibits decent biocompatibility and excellent NIR-II fluorescence properties,which significantly improved the selective uptake of probe by tumor cells through a linear self-assembly strategy.Upon intraperitoneal injection,APP-Ag₂S-RGD exhibits the unparalleled detection sensitivity during the surgery of cancer peritoneal metastasis.This novel and efficient nanochain probe make a great promise for future clinical fluorescence-guided tumor staging,preoperative diagnosis and intraoperative navigation.