Silver Nanoparticles And Super-Paramagnetic Iron Oxide Nanoparticles For Capture,Enrichment,Detection And Release Of CTCs

Circulating tumor cells（CTCs）are cells shed from a primary or metastatic tumor and circulate in the blood stream,which could cause horrible metastasis of cancer.Therefore,researches on CTCs have attracted tremendous attention in the past decade.Detection of CTCs as a liquid biopsy of tumor can be used for early diagnosis of cancer,early assessment of cancer recurrence and chemotherapeutic efficiency,and individual choice of anticancer drugs.As a consequence,CTC detection plays a key role in cancer theranostics.In the first part of this dissertation,triangular silver nanoprisms（AgNPR）with function of surface-enhanced Raman scattering（SERS）and superparamagnetic iron oxide nanoparticles（SPION）were developed and utilized for capture,enrichment,detection and release of CTCs via synergistic action of both nanoparticles.In the second part,silver nanoparticles（AgNP）were prepared with different methods.Mercuric propionic acid and cysteamine were modified on the surface of AgNP.Dimers of AgNP were obtained through the reaction of carboxyl groups and amino groups to enhance the surface plasma resonance,SERS signal intensity,and detection sensitivity of CTCs.The specific research contents include the following two aspects:（1）Capture,Enrichment,Detection and Release of CTCs Based on AgNPR and SPION:First,AgNPR with a diameter of 60 nm that is used as SERS substrate was modified with 4-mercaptobenzoic acid（MBA）,a Raman reporter,via Ag-S bond（MBA-AgNPR）.Then,the MBA-AgNPR was further modified with reductive bovine serum albumin（rBSA）（MBA-AgNPR-rBSA）to enhance its stability and reduce its nonspecific recognition to normal cells in the blood.Next,the folic acid（FA）was grafted to the surface of MBA-AgNPR-rBSA via the reaction between-COOH of FA and-NH₂ of rBSA to obtain MBA-AgNPR-rBSA-FA nanoparticles.Afterwards,SPION was modified with rBSA and FA as well to obtain SPION-rBSA-FA.Finally,a supersensitive CTC analysis system was developed via synergistic effect of MBA-AgNPR-rBSA-FA and SPION-rBSA-FA.This system we developed was capable of recognizing and capturing cancer cells with FA receptor of FRα,enriching the captured cells through magnet,and detecting the cancer cells in the blood by means of SERS.Moreover,the SERS intensity has a linear relationship（R²=0.993） between the concentration of cancer cells within 1-100 cells mL^-1,which enables the supersensitive as well as quantitative analysis of CTCs.Furthermore,after the capture and enrichment progress of our system,the CTCs could also be released via addition of excessive free FA for further cell expansion and phenotype identification.（2）Preparation of AgNP Dimers with Stronger SERS Signals:Mercaptopropionic acid and cysteamine were modified on the surface of AgNP with a diameter of²0 nm,respectively.The AgNP dimers were prepared via the amide reaction which combined the carboxyl group of the mercaptopropionic acid with the amino group of the cysteine.SERS signal molecules were further modified on the surface of the AgNP dimers to obtain stronger SERS signal and CTCs detection sensitivity.