Study On Photoinduced Regenerative Electrochemical Aptasensors And Logic Gates

Nucleic acid aptamers are oligonucleotide chains or polypeptide molecules that bind to specific target molecules with high affinity.They are considered as potential substitutes for antibodies and have broad application prospects in basic research and actual sample analysis.As a low cost,simple operation,high sensitivity and low background signal detection method,electrochemical detection technology has been widely used in the field of biochemical analysis and detection.The combination of electrochemical biosensors and DNA molecular logic gates is of great significance for realizing the practicality of DNA molecular logic.The aim of this paper is to construct photoinduced regenerative biosensors based on nucleic acid aptamers and DNA molecular logic gates by using electrochemical detection techniques and to detect biological molecules.The main contents are as follows:(1)A photoinduced regenerative electrochemical sensor based on nucleic acid aptamer was constructed for the detection of adenosine triphosphate(ATP).The photoresponsive ATP aptasensor was prepared by inserting azobenzene into the ATP aptamer chain and modified it on the gold electrode.After bound to the target molecule ATP,the conformation of aptamer transformed into hairpin structure.Under ultraviolet light irradiation,the azobenzene structure would undergo trans-cis isomerization,and the hairpin structure of the aptamer could be destructed by dissociation of four pairs of bases,thereby realizing the regeneration of the sensor.Under the optimal conditions,the electrochemical response signal of the sensor and the logarithm of ATP concentration were linear in the range of 1 nmol/L?100 ?mol/L,and the detection limit was 0.50 nmol/L(S/N=3).In addition,the sensor has good selectivity and could detect ATP in the rat brain cortex microdialysate.(2)A photoinduced regenerative electrochemical aptasensor based on G-quadruplex structure was designed to detect thrombin.The azobenzene was inserted into thrombin aptasensor and combined with the target molecule thrombin to form a G-quadruplex structure.The azobenzene configuration was changed by ultraviolet light irradiation,and the folding region of the aptamer was opened to realize sensor regeneration.The experimental results showed that the logarithm of thrombin concentration in the range of 5 pmol/L-5 ?mol/L has a good linear relationship with the electrochemical response signal,and the detection limit was 0.31 pmol/L(S/N=3).At the same time,the sensor has good selectivity for the detection of thrombin.(3)A photoinduced regenerative electrochemical aptasensor was constructed for detecting platelet-derived growth factor BB(PDGF-BB).At the same time,the "NOR"DNA molecular logic gate was constructed by using ultraviolet light and guanidine hydrochloride as input signals.The azobenzene was inserted into PDGF-BB aptamer and modified the aptamer on a gold electrode,and when the nucleic acid aptamer specifically bound to PDGF-BB,a pseudoknot structure was formed.By the action of ultraviolet light irradiation and guanidine hydrochloride,the pseudoknot structure of the aptamer was opened,and the regeneration of the sensor was realized.The results showed that the electrochemical response signal of the sensor has a linear relationship with the logarithm of PDGF-BB concentration in the range of 5 pmol/L to 500 nmol/L.The detection limit was 0.28 pmol/L(S/N=3).And this sensor has good selectivity for the detection of PDGF-BB.The aptasensor could measure PDGF-BB in the rat brain cortex microdialysate.