Biomimetic Fibrous Membrane For Capture And Release Of Circulating Tumor Cells

Detection and isolation of circulating tumor cells(CTCs)from peripheral blood is of great significance for the early diagnosis,postoperative monitor and the study of the metastasis mechanism of cancer.However,it is still technologically challenging to isolate CTCs due to their extreme rarity in peripheral blood.In addition,the purity and vitality of CTCs are seriously affected by nonspecific adhesion of blood cells and invasive release methods.Nanofibers with extracellular matrix(ECM)-mimicking structures have large specific surface area for providing plenty of contact sites,thus enhancing the recognition between cells and materials.Some polymer brushes have been found to have structures similar to cell membrane structure and excellent antifouling performance to resist the nonspecific adhesion of other blood cells.Red light,which is friendly to cells,spatiotemporally controllable and simple to operate,has been widely used in biomedical field.Inspired by these,this thesis intends to construct a novel functional fibrous membrane by combining electrospinning,polymer brushes and red-light responsive unit.This functional fibrous membrane,which has structures similar to that of ECM and cell membrane,could achieve efficient capture and noninvasive release of CTCs.Firstly,tetra methoxy azobenzene(mAzo)was synthesized.The structure was characterized by Fourier transform attenuated infrared spectroscopy(FTIR)and ~1H nuclear magnetic resonance(~1H-NMR),and the results proved that mAzo was successfully synthesized.The photoisomerization property was measured by UV-Vis absorption spectroscopy(UV-Vis).And the results showed that the transformation of cis-trans isomerization was successfully achieved under red light at 620 nm and blue light at 470 nm.It was demonstrated that there was host-guest interaction between mAzo and carboxymethyl?-cyclodextrin(CM-?-CD).Secondly,a functional fiber membrane with dual-biomimetic structure was constructed.Polycaprolactone(PCL)nanofiber membranes(PNFs)with a diameter of 250±50 nm were prepared by electrospinning.Then,poly 2-methylacrylloxyethylphosphoric acid(PMPC)and poly methacrylate acid(PMAA)brushes were successively grafted onto PNFs by surface-initiated atom transfer radical polymerization(SI-ATRP).At last,3-aminobenzeneboronic acid(APBA)was linked to the substrate using the complex of mAzo and CM-?-CD as the bridge.The morphology,chemical structure and wettability of nanofiber membrane were characterized by scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS)and water contact angle(WCA),respectively.All these results proved that the functional nanofiber membranes were successfully prepared.Finally,the CTCs-isolation performance of functional fiber membranes from cell suspension and blood was investigated.Cytotoxicity assay and platelet adhesion were performed,showing that the functional fiber membranes had good cytocompatibility and antifouling properties.Then the functional fiber membranes showed excellent capture efficiency(>88.7%)towards human breast cancer cells(MCF-7),human liver cancer cells(Hep G2)and human cervical cancer cells(He La).And the release efficiency of captured cells increased with irradiation time and could reach as high as 94.1%after 10 min.The released cells with vitality of 93.6%showed intact structures and good proliferation ability,which were evidenced by fluorescent and SEM images.Furthermore,the separation performance of functional fiber membranes towards CTCs from artificial samples and cancer patients'blood were systematically investigated.For artificial samples,low concentration of CTCs(100-3000cells/m L)could be detected.Furthermore,functional fiber membranes could identity CTCs in14 of 16(87.5%)patients with a purity of 91.7%.