Research On The Preparation Of Three-dimensional Granphene Aerogel Microfluidic Biochip Applied For The Early Diagnosis And Deteciton Of Cancer

Due to the low cure rate of terminal cancer,people hope to restrain the illness and remove or kill tumor cells before the mutation of cancerous tissues in the early stage of cancer,and furtherly to cure the disease.Hence,the early detection and diagnosis?EDDC?of cancer has been a hot research topic for recent years in the scientific community.With ongoing endeavors and explorations,researchers have developed many techniques applied for EDDC based on the knowledge and methods of physics,chemistry,biology,etc.This essay is the research on the design,preparation and application of a three-dimensional graphene aerogel?3D GA?-based microfluidic biochip.To demonstrate the potential for EDDC,the chip is utilized to the quantitative and qualitative detection of typical tumor markers and exosomes via electrochemical immuno assay.The main content of the essay consists of the following three parts:1)The prototype and preparing method of the micro-biochip applied for electrochemical immuno detection is proposed.A three-electrode system was integrated in the chip,wherein the Indium-tin-oxide?ITO?conducting glass was utilized as the substrate and the silver paste was exploited as bonding layer.The GA film was prepared via in-suit reduction of graphene oxide?GO?on the surface of silver paste and then functioned as the working electrode.The GA film was functionalized with pyrene formic acid?PCA?to introduce carboxyl groups and then worked as detecting electrode.Via digital microscopy and scanning electron microscopy?SEM?,abundant and cross-linked wrinkled structures on the surface and pores and fissures across the intersecting section were observed.This 3D morphological property endows the GA/Ag/ITO electrode with an immense specific surface and a rather small AC impedance?⁹ k??.?2?Electrochemical impedance spectroscopy?EIS?was exploited to detect and analyze typical tumor markers?IgG,CEA,AFP?in order to demonstrate that the chip is highly sensitive and selective and has relatively a wide linear response range and a low detecting limit.In the detection,target antigens were immobilized on the surface of the working electrode via immuno adhesion and furtherly hinder the electron transmission in the electrode-electrolyte interface and enlarge the AC impedance response of the working electrode.The concentration of the detection object can be determined the variation of impedance responses.The experiments demonstrated that the biochip has a good sensitivity and selectivity,along with a wider linear range and lower detection limit than conventional methods in detection of typical tumor markers.Moreover,the chip can also be utilized to qualitatively detect tumor cells derived exosomes,which can be potentially applied for the early diagnosis of cancer and monitoring the recovery of post-surgery patients.?3?Gold particles and GA?AuNPs@GA?composite was tentatively utilized as the working electrode and the effect of different preparing methods on the electrical and chemical properties was explored.Various amounts of chlorchloric acid?HAuCl₄?were added during the reduction procedure of GO which functioned as the crystal nucleus of gold particles and furtherly to prepare AuNPs@GA composite via one-step chemical reduction.Under the SEM observation,most of gold particles were found immobilized around the wrinkle and pore structures of GA.The experiments suggested that when the concentration of added HAuCl₄ is under 2 mg/mL,the prepared composite has good homogeneity and the diameters of most gold particles are around dozens to hundreds of nanometers.Via EIS detection,it wasdemonstrated that the AC impedance response of AuNPs@GA/Ag/ITO electrode is roughly the quadratic function of logarithmic HAuCl₄ concentration.The introduction of gold particles enlarged the impedance of the working electrode which is probably owing to the effect of the growth of gold particles on the self-assembly of GO molecules and the formation of 3D structures.Another cause may be the existence of isolated materials in the resulted composite.The optimum preparing method and applications of the AuNPs@GA chip still needs further research and explorations.