Photoelectrochemical Biosensors Based On 2D/2D Nanocomposites And Its Application In Tumor Marker Detection

Cancer,named as malignant tumor,is one of the main causes of death.Tumor markers are a kind of substance existing in malignant tumor cells.The level of biomarkers can be regarded as one of the signs whether people have malignant tumor or not.It has made an important contribution to the early screening and postoperative monitoring for cancer.On the basis of electrochemistry,photoelectrochemical?PEC?immunoassay introduces the concept of light and then combines light with electricity perfectly.Compared with electrochemical immunosensors,the PEC immunosensors have higher sensitivity and wider prospect in clinical application in the future.Photoactive materials are the core element for the construction of PEC immunosensors.The appropriate photoactive materials determine the analytical performance of the biosensors.Among them,two-dimensional?2D?nanomaterials have many advantages,such as large specific surface area,good optical and electrical properties and so on.In this paper,the ultrasensitive PEC immunosensors based on 2D/2D nanocomposites were constructed by taking carcinoembryonic antigen?CEA?and carbohydrate antigen 724?CA724?as targets.The main contents of the study are as follows:?1?An ultra-sensitive PEC immunosensor for the detection of CEA based on 2D/2D GO/MoS₂ heterostructure was constructedThe flower-like 3D GO/MoS₂ heterojunction as photoelectric conversion layer was synthesized by hydrothermal method and characterized by TEM,SEM,XRD,UV-Vis,et al.A double antibody sandwich immunoassay based on specific binding of antibodies and antigens was developed by using Rhodamine?Rh123?and CdS labeled secondary antibodies?Ab₂-Rh123@CdS?.Because of the band gap matching between Rh123 and GO/MoS₂ semiconductor,the photocurrent can be amplified.Under the optimal experimental conditions,the detection limit of CEA is 3.2 pg mL^-1,and the photocurrent increases linearly in the range of 10 pg mL^-1?80 ng mL^-1.?2?A dual signal reduction PEC platform based on 2D/2D g-C₃N₄/BiOCl heterostructure was proposed for CEA detectionUnder visible light irradiation,g-C₃N₄/BiOCl semiconductor modified on ITO electrode is easy to obtain photocurrent.In the presence of L-cysteine?L-Cys?,the photocurrent increases significantly due to the rapid separation of photo-induced electrons and holes.Then,using CuO NPs as label,a sandwich immunoassay was constructed on 96-well microtrickle plate.Under acidic conditions,Cu²⁺is released from CuO,and the released Cu²⁺can not only chelate with L-Cys,but also act as the electron acceptor of g-C₃N₄ and BiOCl,which greatly reduces the photocurrent of L-Cys-assisted PEC system.The photocurrent decreases with the increasing of CEA concentration.Under the optimal conditions,there is a good linear relationship between the photocurrent and the concentration of CEA in the range from 0.1 pg mL^-1 to 10 ng mL^-1.In addition,the photoelectrochemical immunosensor has good selectivity,repeatability and stability.?3?A signal amplification PEC biosensor was built for trace detection of tumor marker CA724 based on 2D/2D g-C₃N₄/MoS₂g-C₃N₄/MoS₂ semiconductor was selected as photoelectric nanomaterial and characterized by TEM,FT-IR,XRD and UV-Vis.In addition,magnetic Fe₃O₄ nanospheres are used as a platform for the construction of PEC sandwich immunoassays.Subsequently,the Etion Y was encapsulated in the CaCO₃nanospheres and used as anti-CA724 lables.In the presence of ethylenediaminetetraacetic acid?EDTA?,the CaCO₃ nanospheres were dissolved and the red Etion Y inside was released.The g-C₃N₄/MoS₂semiconductor on the electrode was sensitized resulting in increased photocurrent.Under optimal conditions,the photocurrent increases linearly in the range from 0.05 mU mL^-1 to 500 mU mL^-1 and the detection limit is 0.02mU mL^-1.