| Prostate cancer often occurs in middle-aged and elderly men.Early detection of cancer has become the key to alleviating pain,prolonging lifespan,improving survival rate and reducing mortality,because cancer is easy to metastasize and difficult to cure in the middle and late stages with a long onset cycle.Prostate cancer-specific antigen(PSA)is a protein secreted by the prostate gland and is an important diagnostic marker for prostate cancer.In this paper,an electrochemical biosensor is developed using screen printed electrode(SPE)and graphene aerogel(GA),which can detect PSA sensitively.The sensor is simple in structure,light in appearance and cheap in cost,so it has the development prospect of portable detection.The main contents of this article are as follows:(1)A screen-printed electrochemical three-electrode system was designed and fabricated,the three-dimensional graphene aerogel was modified on the working electrode,and its morphology,structure and electrochemical performance were characterized.Firstly,the pattern of the screen printed electrode was designed and the key parameters such as electrode structure,electrode size,area ratio were optimized to meet the requirements of one-shot high-volume manufacturing.Secondly,chemical reduction method and freeze-drying process were used to modify the three-dimensional graphene aerogel on the working electrode and Nafion was doped with to improve the stability of the working electrode.Secondly,the graphene aerogel was modified on the electrode by freeze-drying method,and Nafion was doped into GA to prevent the modified layer from falling off the electrode surface.Finally,the morphology and structure information of the aerogel was characterized by electron microscopy and Raman spectroscopy,and its electrochemical performance was tested by cyclic voltammetry,electrochemical impedance spectroscopy and other techniques.(2)The high specific surface area of graphene aerogel was utilized to modify antibody on to develop an electrochemical immunosensor,and the performance of the sensor was tested and analyzed.Alpha-fetoprotein(AFP)was used to verify the feasibility of the sensor principle.Graphene aerogel was firstly carboxylated,and the AFP antibody was covalently immobilized by amide bonds,so as to realize the modification of the biosensitive layer,and then different concentrations of AFP was detected;Based on the feasibility of the principle,the PSA antibody was modified on graphene aerogel to optimize the key parameter of antibody concentration,and the PSA was quantitatively detected by electrochemical impedance test to obtain key indicators such as linear range(0.1 ng/m L-10 ng/m L)and lower detection limit(0.061 ng/m L).And conduct selectivity and stability tests.(3)In order to further improve the specificity and stability of the electrode,aptamers were used to make the bio-sensitive layer,PSA electrochemical aptamer sensor was developed,and the performance of the sensor was tested and analyzed.In order to develope PSA electrochemical aptamer sensors,gold nanoparticles were modified on graphene aerogels to immobilize PSA aptamers and to replace PSA antibodies.The modification concentration of gold nanoparticles was adjusted,the concentration of aptamers was optimized,and using conditions of the aptamer was tested.Then,electron microscope was carried out to characterize the working electrode was carried out to establish the optimal assembly conditions of the sensor;At last,electrochemical impedance test was used to quantitatively detect PSA,and key indicators such as linear range(0.05 ng/m L-50 ng/m L)and detection limit(0.0306 ng/m L)were obtained,and the selectivity test was carried out. |
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