Synthesis Of Click-functionalized Nanoprobes And Their Application In Cancer Diagnosis

With the deepening research on nanoscience and nanotechnology,various optical enhancement effects of nanostructures are continuously revealed.Using the information provided by these nano-optial effects and surface biological modification technology,we can design and develop a series of chemo/biosensors with high sensitivity and selectivity.Compared with the existing biomedical diagnostic methods,nano-optical effect sensors not only have excellent signal amplification capability,but also have the advantages of low cost,rapid response and convenience.In this dissertation,we prepared folate receptor-targeted fluorescent silica nanoprobes and surface-enhanced Raman scattering(SERS)nanoprobes based on the click chemistry modification strategy at the surface of nanoparticles,and both of which had been successfully applied to cancer cell imaging,respectively.In addition,we designed phosphorylation-induced silver nanoparticle aggregates and achieved the sensitive detection of protein kinase A activity by using SERS hotspots and the spectroscopic techniques.The main research contents are summarized as follows:(1)Novel folate receptor-targeted fluorescent nanoprobes were constructed by modifying Rubpy-doped silica nanoparticles with folic acid based on click chemistry coupling method,which had been successfully used for cancer cell imaging.The cell imaging results showed that the nanoprobes could effectively target folate receptor-positive HeLa cells,while no obvious fluorescence was observed for folate receptor-negative A549 cells.The receptor-mediated imaging mechanism was confirmed by free folic acid competition experiments.More importantly,HeLa cells could be selectively recognized and imaged in the mixing cell system.Compared with the carbodiimide conjugation protocols,the click-functionalized nanoprobes had the advantages of simple synthesis procedures,mild reaction conditions and high yields.By selecting different biological ligands and combining with the efficient surface modification property of click-chemistry,this strategy is expected to become a versatile method for preparing multifunctional bioluminescent nanoprobes.(2)Raman-active molecules that contained azide groups were designed,synthesized and covalently modified at the surface of hollow gold nanoparticles,and a novel SERS nanoprobe with high labeling efficiency and good cell-targeted capability was developed by further conjugating with folate derivatives that contained alkyne groups,and the nanoprobes had been successfully used for the selective recognition and SERS imaging of tumor cells with high folate receptor expression.Compared to the results of the molecular fluorescence probes,the SERS nanoprobes could effectively reduce or avoid their non-specific adsorption on the cell surface,and are expected to become ideal contrast agents for tumor targeted imaging and therapy.(3)Phosphorylation-induced silver nanoparticle aggregates were designed by using spermine-modified silver nanoparticles and the charge changes of peptides before and after their phosphorylation,and the highly sensitive detection of protein kinase A activity was successfully achieved through the SERS signal readout of the labeled peptides.Meanwhile,the sensitivity and reliability of the proposed method had been confirmed by the drug stimulation experiments and the results of protein kinase A activity in cell extracts.