| Circulating tumor cells(CTCs)are a kind of cells that fall off from the original lesion and enter the peripheral blood.The number of CTCs in the blood is very small,and the enrichment and capture of CTCs have been a research hotspot.In the previous work of our group,the nano-fish cage structure of pollen can achieve efficient and rapid capture of CTCs without immunolabeling,but the pore size of pollen is constant and difficult to regulate.This work proposed a composite nano-frame structure to simulate the nano-cage structure.The structure is composed of vertical nanowire arrays penetrating inside and rich nanofibers on the top of the arrays.This novel three-dimensional composite nano-frame structure has the advantages of size controllable properties and artificial large-scale preparation.The optimized structure is conducive to tumor cell pseudopodia expansion and adhesion,and can be applied to achieve efficient capture of tumor cells.The main research contents of this paper are as follows:(1)The metal-assisted etching method was used to prepare silicon nano-arrays,and the silicon nano-array structure was optimized for tumor cell capture.First,masking technology is used to spread a layer of precious metal on the surface of the silicon wafer as a catalyst.Along with the masking time,the smaller density of nanowires in the silicon nanoarray was obtained.For further etching,hydrofluoric acid was used to etch silicon that contacts with precious metals.With the prolonged etching time,the longer nanowires were etched,and even fractures may occur.The silicon nano-arrays with the optimized conditions could capture79±9% of human epidermal squamous cells(A-431),while having a certain anti-adhesion effect on white blood cells.(2)The electrospinning technology is used to prepare the nanofiber membrane of silk fibroin/lactic acid-caprolactone copolymer with nano cobwebs and regulate its structure.Select the biocompatible silk fibroin/lactic acid-caprolactone copolymer material,and determine the best electrospinning conditions at room temperature,with a total concentration of 10%(50:50),spinning voltage 10 KV,receiving a distance of 20 cm,and perfusion speed0.12 mm/ min.The diameter of the optimized nanofiber was 900 nm,and the diameter of the nano cobweb is 35 nm.The presence of the nano cobweb increased the contact area between the nanofiber membrane and tumor cells.The two-dimensional membrane structure of silk fibroin/lactic acid-caprolactone copolymer nanofibers can achieve a capture rate of 78±4% of tumor cells(A-431).(3)We constructed a composite nano-frame membrane material combining silicon nano-array and nano-fiber membrane,and investigated the effect of both combination on the capture of tumor cells.Electrospinning three kinds of nanofiber membranes with random,single orientation and double orientation on the surface of silicon nanoarrays.The composite nano-frame membrane material prepared in dual orientation can effectively expose the inner vertical nanowire array due to the neat arrangement of the surface fiber membranes.the obtained three-dimensional structure combining single-layer silicon nanoarrays and electrospun nanofiber membranes was similar to the nano-fish cage structure and could achieve 88±7% tumor cell(A-431)capture efficiency.In addition,we found that the silk fibroin/lactic acid-caprolactone copolymer nanofiber membrane can promote tumor cells to grow out of band pseudopodia,and tumor cell pseudopodia are more likely to stretch under the nanofibers.The anti-adhesion effect of the composite nano-frame membrane material was investigated on the background white blood cells,showing only 10% adhesion to white blood cells with a certain anti-adhesion effect.In summary,in this thesis,we constructed a new type of composite nano-frame membrane material for effective capture of tumor cells,which is expected to be applied to the rapid diagnosis of cancer,and provides a new way for tumor cell capture. |
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