Rough Surface Of Multilayer Silla Nanoparticles And Its Highly Efficient Capture For Circulating Tumor Cell

In this paper,aminosiloxane(SiO2-APTES)nanoparticle with different surface charges was firstly synthesized by exploring the synthesis conditions of SiO2-APTES nanoparticle.SiO2-APTES nanoparticle with a surface potential of-16mv was chosen to construct the rough surface of multilayer silla nanoparticles to reduce the nonspecific adsorption of scaffolds during cell capture.Polyacrylic acid(PAA),SiO2-APTES,PAA,SiO2-APTES,PAA,and SiO2-APTES were connected on silanized glass slides by chemical cross-linking method in order.In other words,the scaffolds structure was:substrate-PAA-SiO2-APTES-PAA-SiO2-APTES-PAA-SiO2-APTES,thus a nanoscale three layer nanoparticles scaffold was obtained.According to the preliminary research of our research group,in order to achieve effective construction of rough surface of multilayer nanoparticles,for the molecular weight of PAA,we designed two combination sequences,namely sequence 1"1000000,50000,8000" and sequence 2 "50000,8000,5000" so that two systems of multilayer nanoparticle scaffolds were constructed.Through the characterization of ultraviolet spectrophotometer,scanning electron microscope and atomic force microscope,it was found that through the PAA chemically cross-linked multilayer nanoparticle scaffolds of sequence 2(referred to as chemical cross-linked scaffolds for the convenience of expression)were superior to that of sequence 1 in terms of nanoparticle immobilization loads and roughness,which has a obviously rough and uneven nanoscale layered structure,and the roughness of part area can be up to 50.9nm.At the same time,using unactived PAA of sequence 2 to directly construct the rough surface of three layer nanoparticle scaffolds(namely,the three layer nanoparticle scaffolds assembled by electrostatic adsorption,for the convenience of expression,referred to as electrostatic assembly scaffolds)as a control.It was found that the immobilization loads and roughness of the nanoparticles were lower than that of the chemically crosslinked multilayer nanoparticle rough surface.Therefore,a highly rough nanosurface was successfully optimized and constructed.PAA(M=2000)and the nucleic acid aptamers of A549 cells were chemically linked on the chemical crosslinking scaffold,which enabled the scaffold specifically capture A549 cells.As the layers of scaffolds increased,the surface roughness gradually increased,so increasing the ability of scaffolds capturing cell.Compared with scaffolds of one layer,two layer and three layer yielded 1.4 and 2.6 times more cells than one layer scaffolds.At low cell density(2070/ml in 5ml),highly capture efficiency can be achieved(8000,77%),and even at an extremely low cell density(46 in 5ml),the capture efficiency can be as high as 71%(an average of 33).However,the electrostatically assembled scaffolds showed significant difference in the capture performance for A549 cells.Firstly,the increase in layers of scaffolds did not contribute significantly to the increase of captured cells.At an extremely high cell density(150000/ml in 3ml),one layer,two layer,and three layer scaffolds yielded cell capture of 2080,1920,and 3040 respectively.At such a high cell density,the captured cells of the three layer electrostatically assembled scaffolds were only up to the mean number of 3040,even far lower than that of the chemically crosslinked scaffold at a low cell density(2070/ml in 5ml)(mean of 8000).It is shown that the optimized multilayer nanoscale rough surface can effectively capture CTCs(circulating tumor cells).On the basis of the aforementioned substrate research work,silica nanoparticle scaffolds of three layers were also immobilized in a 1mm glass capillary tube by PAA cross-linking reaction.The results showed that the blank capillaries exhibited strong adsorption in both low and high density cell suspensions when capturing cells in the static state,and the adsorption was over 72%.When capturing cells in cycle system,it's found under high velocity of 54ml/min,aptamer modified three layer nanoparticles scaffolds capillary is over undecorated aptamer modified three layer of 28600 cells,in the same surface area of plate,aptamer modified single layer,two layers,three layers of capillary capture cell number is 8861,10512,18586 respectively,and only 3661,5247,9760 on plate.In addition,in the low-density cell suspension(50/ml),the capture efficiency of the three-layer nanoparticle scaffold capillary was still 80%,and 50%when excluding the blank tube.such excellent capture performance of rough surface of multilayer nanoparticles in capillary tube is determined by two factors.Firstly,the nanoscale structure and high roughness of the scaffolds;Secondly,the capillary has a large specific surface area and a small diameter.In summary,a highly rough nanoscale surface was constructed in this paper to achieve highly efficient capture for CTCs.Combining this system with in vivo capture is promising to achieve highly sensitive detection of CTCs in clinical.