Research Of The Establishment Of Electrochemical Biosensor Based On Quantum Dots And Application In Detecting Cancer Cells

Cancer,as a seriously hazard disease to human's health in the world,is one of the three major diseases and the early diagnosis of tumor cells is vital.Quantum dots electrochemical sensor can detect tumor cells accuratly and rapidly while this electrochemical detection method is the focus in the domestic and foreign scientists all the time.Based on the improvement of electrochemical detection sensitivity,this paper designs the“sandwich”electrochemical sensor for detecting tumor cells and provides the feasibility scheme for the more convenient,sensitive detection in the future.The primary coverage is displayed as follows:?1?A novel ultrasensitive electrochemical biosensor was developed for the detection of K562 cell by a signal amplification strategy based on multiple layer CdS QDs functionalized polystyrene microspheres?PS?as bioprobe and graphene oxide?GO?–polyaniline?PANI?composite as modified materials of capture electrode.Due to electrostatic force of different charge,CdS QDs were decorated on the surface of PS by PDDA?poly?diallyldimethyl-ammonium chloride??through a layer-by-layer?LBL?assemble technology,in which the structure of multiple layer CdS QDs increased the detection signal intensity.Moreover,GO-PANI composite not only enhanced the electron transfer rate,but also increased tumor cells load ratio.The resulting electrochemical biosensor was used to detect K562 cells with a lower detection limit of 3 cells mL^-1?S/N=3?and a wider linear range from 10 to 1.0×10⁷ cells mL^-1.?2?A novel and green supersandwich electrochemical cytosensor was developed for ultrasensitive detecting tumor cells based on the controlled quantum dots?QDs?-concatamer DNA aptamer probes and the nontoxic“mercury-free”anodic stripping voltammetry?ASV?for K562 cell with new electrode modification composites.Single strand oligonucleotides with phosphorothioate?DNA1?programmed CdTe QDs were assembled on the ssDNA substrate?DNA2?which contained two parts:the controlled several hybridization regions with DNA1-capped CdTe QDs and K562 tumor cell aptamer.The synthesis electrochemical probe achieved the signal controlled amplification.Poly?L-cysteine?/Graphene?GR?-Poly diallyldimethylammonium chloride?PDDA?composites was used for modification electrode to explore in ASV with“mercury-free”detection of Cd²⁺.The much content S,N,O of L-cysteine ensured that Cd²⁺could be absorbed on the modified electrode in the solution even if without mercury.This green electrochemical cytosensor showed high specificity and sensitivity in determining K562 cells with very low LOD.This technique achieved the probe controlled magnification and provides the experimental basis for the preparation of larger ratio of signal amplification probe in order to the purpose of the higher accuracy of detection.In the paper,the design of electrochemical biosensors with quantum dots have realized the sensitivity,wide detection range and green detection technology at the same time,provide a novel approach for detection,diagnosis and treatment for tumor cells.