Construction Of Pt-Se Bond Nanofluorescent Probe And Its Application In Tumor Marker Detection

It is known that cancer is the second leading cause of death in the world.Every year,countless cancer patients are diagnosed at an advanced stage and unable to take effective treatments since they have not undergone cancer screening.Lung cancer is one of the most common cancers in the world.Depending on the type of cancer cell growth,it can be mainly divided into small cell lung cancer and non-small cell lung cancer.Small cell lung cancer accounts for a small proportion and a low degree of differentiation,but it is highly malignant and progresses very quickly.In contrast,non-small cell lung cancer has a large proportion,but its division,growth,and metastasis are relatively slow,making it difficult for early detection.Calpain-2（CAPN2）is a Ca²⁺-dependent cysteine protease that is closely related to angiogenesis,cell proliferation,and migration,which is also one of the important biomarkers for non-small cell lung cancer.However,there is a lack of detection techniques specifically targeting CAPN2,so it is urgent to develop nanoprobes that can detect CAPN2 specifically to achieve the detection of non-small cell lung cancer,diagnose patients at an early stage of cancer,and thus facilitate timely prognosis and treatment to improve the survival rate of patients.Prostate cancer is caused by malignant proliferation of prostate epithelial cells,and is the most common tumor in the male urinary system.Due to its slow progression during onset,it is not easy to detect in the early stages.When the patients aware of it,the rapid growth of prostate cancer usually process to a late stage,making it difficult to achieve ideal therapeutic effects.Currently,the most widely used prostate cancer marker is prostate-specific antigen（PSA）,which h is often used as an important indicator for judging whether it is prostate cancer in the serum,and is also an important parameter for evaluating the prognosis and treatment effect of patients during treatment.Therefore,accurate detection of PSA is necessary for clinical diagnosis.Nanomaterials have become one of the preferred materials for cancer detection due to their nanoscale size,high surface-to-volume ratio,special surface chemical properties,and unique physical properties.Based on the unique physical and chemical properties of nanomaterials,nano-probes have been developed primarily using noble metal nanomaterials,quantum dots and up-conversion nanoparticles,etc.,all of which have different characteristics and advantages,resulting in different performances in detection.Among them,nanoprobes based on noble metal nanomaterials have simple synthesis routes,convenient operation,and streamlined processes.Platinum,as an important noble metal element,has a very low ligand exchange rate,high ligand stability,and a large Pt-Se bond energy,which gives Pt-Se based probes a natural advantage in resisting intracellular biothiols.In this regard,this thesis mainly focuses on researching the following two aspects:I.CAPN2 is a typical cysteine protease and one of the specific markers for non-small cell lung cancer.To achieve its quantitative detection,a Pt-shell coated Pt-Se fluorescent nanoprobe with Au NPs as the core was constructed.A CAPN2-specific peptide chain was modified with Fluorescein 5-isothiocyanate（FITC）at the end and selenol at the other end.The peptide chain was connected to the Pt shell via Pt-Se bonds,resulting in quenching of the FITC fluorescence by florescence resonance energy transfer.When CAPN2 was present,it acted as a cysteine protease to break the specific peptide chain,releasing the FITC fluorescence dye from the quenched Au@Pt NPs surface and thus restoring the fluorescence.The concentration of CAPN2 was determined by the fluorescence signal intensity.In vitro experiments showed that the fluorescence recovery intensity of the probe had a good linear relationship with the concentration of CAPN2,with a correlation coefficient of 0.999.Cell experiments showed that the probe had good intracellular imaging for CAPN2 and could be used to distinguish between normal lung cells and lung cancer cells,achieving high-fidelity imaging and providing a good reference for the detection of CAPN2.II.PSA is a specific marker for prostate cancer,and detecting the amount of PSA in serum can achieve early warning for prostate cancer.Based on the designed CAPN2-specific probe,a Pt-Se prostate-specific antigen probe was designed with 5-Carboxyfluorescein（5-FAM）as the fluorescence dye and prostate-specific antigen-specific peptide chain as the recognition group.In vitro simulation experiments showed that the nanoprobe owns good interference resistance to biothiols and excellent specificity,achieving specific detection of prostate-specific antigen.This work provides a new pathway for the detection of prostate cancer markers and has potential clinical application prospects.