Efficiently Capture Of CTCs By Lable-free Two-dimensional Magnetic Graphene Oxide Composites And Its Cytotoxicity Evaluation

Cancer is considered a worldwide mortal disease and has become a major public concern.Metastasis is the most common cause of cancer-related deaths in patients with solid malignant tumors.During the metastasis process,tumor cells detached from the solid primary tumor,enter the bloodstream and travel to the different sites and organs of the body with the blood circulation.These "break-away" tumor cells in the peripheral blood are called circulating tumor cells(CTCs).Biologists believe that CTCs are the main cause of the distant metastasis of primary tumors and the key to understanding the biological problems of metastasis.As "real-time liquid biopsy",the detection and identification of capture CTCs has great clinical value and can provide valuable information on early diagnosis of tumors,detection of recurrence,prognosis,evaluation of therapeutic effects,screening of anticancer drugs,help in identifying appropriate therapeutic targets and so on.However,the effective separation and enrichment of the extremely rare CTCs in the blood sample is a challenging task and important part of the CTCs detection process.In addition to considering the effective separation of rare CTCs in hundreds of millions of blood cells,it is also necessary to consider the influence of background interference of the vast majority of the background cells(red blood cells and white blood cells)contribute to capture purity issues and viability issues during the capture and separation process,because these factors will affect downstream molecular analyses and further culture of CTCs.CTCs can be currently enriched and detected through different strategies based on the differences hallmarks between CTCs and the normal blood cells in the biophysical properties or biomarkers,however,these separation operations have their own certain limitations thus can not be applied to clinical practice.The difference of glucose metabolic behavior differences between tumor cells and normal cells caused the strong negative surface charge of cancer cell membrance,while the normal blood cells have nearly neutrual surface charge.As a kind of broad-spectrum identification,the negatively-charged membrance of cancer cells can provide a new methodology for effective targeting and capture of CTCs.Our study prepared two kinds of magnetic composite with different shapes and similar surface charge.The effect of morphology on cell capture efficiency and viability was analyzed from the interfacial interaction between materials and cells.The main results are as follows: 1.Successfully prepared negatively-charged carboxylated magnetic nanoparticles(IO-COOH),positively-charged magnetic nanoparticles(IO-PEI)and two-dimensional positively-charged materials composite by reduced graphene oxide and carboxyl magnetic beads(IO-rGO).The particle size and zeta potential of magnetic composites were tested via Malvern zetasizer,the morphology was characterized through TEM and SEM,and we also tested the magnetic properties of these magnetic materials.The concentration of these materials was determined by UV-visible spectrophotometry based on the iron content.2.Due to the electrostatic interaction between positively-charged materials and negativelycharged cancer cell membranes,the capture efficiency of cancer cells by two kinds of positiveiy-charged magnetic composites which have different morphology is much higher than that of negative electromagnetic particles.The two-dimensional(2D)positive magnetic composite of IO-rGO has high capture efficiency than positive magnetic nanoparticles of IOPEI under the same magnetic content,therefore,when a certain capture efficiency requirement is met,the amount of material can be reduced by use IO-rGO with the optimum working concentration is 0.02 mg/mL.3.Two-dimensional positive magnetic composite has greater effect on cell viability than positive spherical magnetic nanoparticles.We discuss the causes of toxicity of cells to materials from a combination of material usage,surface charge,size and material morphology.The results show that the main cause of IO-rGO toxicity is its morphology.