Capture,Enrichment,Detection And Release Of Circulating Tumor Cells Based On Gold-Iron Composite Nanoparticles

When tumor develops to a certain stage,tumour cells will shed into the vasculature from tumors and form circulating tumour cells(CTCs).Most CTCs will undergo phagocytosis or apoptosis after entering peripheral blood,but a few may escape.The escaped CTCs could form microthrombosis through cell migration,adhesion and aggregation under specific conditions.Finally,cancerometastasis is formed.There are5 billion red blood cells and 10 million white blood cells but few CTCs in 1 mL of the blood.Surface-enhanced Raman Scattering(SERS),which greatly enlarges the spectral signal of a single molecule by utilizing the property of noble metal nanoparticles,is one of the best methods for the detection of CTCs.Gold-iron composite nanoparticles combine the magnetic property of superparamagnetic iron oxide nanoparticles(SPION)with the surface plasman resonance(SPR)effect of gold nanoparticles(AuNPs),realizing the detection and separation of CTCs simultaneously.This thesis mainly includes:(1)Preparation of core-shell iron/gold composite nanoparticles and the application for CTCs detection.First,SPION coated with polyacetamide(PEI)was prepared by a solvothermal method,and AuNPs were prepared by a sodium citrate reduction method.Negatively charged AuNPs were assembled on the surface of SPION-PEI with opposite charges due to the electrostatic interaction.The assembly makes the electromagnetic fields between adjacent AuNPs superimposed,which creates SERS hotspots and enhances SERS signal intensity.Subsequently,4-mercaptobenzoic acid(MBA),which acts as a Raman signal molecule,was adsorbed on the surface of AuNPs via Au-S.Finally,the complex of reductive bovine serum and albumin-folate(rBSA-FA)targeting cancer cells was coated to improve the stability of magnetic composite nanospheres.The composite nanoparticles were applied to capture,enrich and detect CTCs.The limit of detection(LOD)was 1 cell/mL.When the number of cancer cells was1-25 cells/mL,there was a good linear relationship between SERS intensity and concentration of cancer cells(Y=13.78 X+80.287,R~2=0.9929).The capture efficiency and purity can reach 91%and 78%.Excess folic acid(FA)was co-cultured with captured cells to release magnetic composite nanomaterials.The results showed that the state of cells released from magnetic composite nanomaterials was better than that of unreleased,which provided the possibility for further culture,amplification,identification and molecular phenotype analysis of CTCs.Lastly,a clinical trial for two first-stage patients with cervical cancer was studied.The result showed that the concentrations of CTCs in blood were 6±2 and 13±5 CTCs per 10mL of blood,respectively.(2)Preparation of core-shell gold/iron composite nanoparticles and the application for CTCs detection.Triangular gold nanoprisms(AuNPRs)were prepared by an oxidation etching method,and the purity of AuNPRs was improved by dissipation.Zeta potential characterization showed that the zeta potential of AuNPRs was 25.3 mV.TEM characterization showed that the edge length of AuNPRs was between 60 and 70 nm.After modification with MBA,the SERS intensity of AuNPRs was positively correlated with MBA concentration.SPION was then prepared via polyol method.Zeta potential characterization showed that the zeta potential of SPION was-53.4 mV.TEM characterization showed that the particle size of SPION was about 5 nm.Both AuNPRs and SPION dispersed well in water.Based on the electrostatic interaction,AuNPRs with opposite zeta potential were mixed with SPION.Then rBSA was added to the mixture based on the interaction between Au-S and amide bond to explore the connection between AuNPRs and SPION.