Research On The Electrochemical Micro-nano Sensing For The Determination Of Transaminase

Point-of-care testing is a rapid detection technology besides the patients, which has the advantages of portability, simple operation and rapid analysis and so on. It is widely used in clinics. Transaminase is an important metabolic enzyme exiting in the human being's organs such as liver and heart. It is often regarded as the biomarker for the organ damage. The methods for the transaminase detection in clinics, which require trained operators specific laboratory and bulk equipment, are not suitable for the point-of-care and rapid detection, especially for the injured in the battlefield and the disabled patients. In this paper, a series of researches combined with the 3D printing electrochemical sensor, nano effect, microfluidic technology and electrokinetic nanofluid enrichment were conducted in order to realize the detection for transaminase with high sensitivity in a point-of-care way. The main contents are as follows.For the first time, a new electrochemical determination system for the GPT activity based on the transdeamination is proposed, which combines the electrochemical detection of NADH with the determination of GPT activity and gets rid of the situation that the detection for transaminase is excessively dependent on the oxygen. At the same time, this system has the advantage of specificity over other systems because of the participation of glutamate dehydrogenase ?GLDH? which has absolute specificity for the L-glutamate. Then the system is verified using the cyclic voltammetry with the purchased screen-printed carbon electrode ?SPCE?. A linear relationship ?R2=0.97219? between the activity of transaminase and the current response is obtained in the range from 60U/L to 300U/L with the sensitivity of 0.08171 ?A·cm-·U^-1·L. And the responses of CNT modified SPCE and bare SPCE are compared. The results show that the CNT modified SPCE has a better current response.In order to improve the performance of electrochemical sensor and the sensitivity of the detection for transaminase, the electrochemical sensor and the graphene modified electrode are fabricated through 3D printing. The electrochemical experiments for the transaminase detection are conducted with this sensor. Two linear relationship between the activity of transaminase and the current response in the range of 20U/L to 250U/L is obtained ?R2=0.90598 in the range from 20U/L to 50U/L, R2=0.97962 in the range from 50U/L to 250U/L?. The sensitivities for the two ranges are 0.85385 and 0.18809?A·cm^-2·U^-1·L. At the same time, the responses for NADH of graphene modified electrode and carbon electrode are compared. The results show that the modified electrode has a better current response and a lower oxidation potential.The microfluidic electrochemical sensing chip was constructed in order to realize the combination of microfluidic technology and electrochemical detection system. The electrochemical experiments for the transaminase detection are conducted with this chip. Two linear relationship between the activity of transaminase and the current response in the range of 10U/L to 250U/L is obtained ?R2=0.97986 in the range from 10U/L to 50U/L, R2=0.99173 in the range from 50U/L to 250U/L?. The sensitivities for the two ranges are 0.14029 and 0.08893?A·cm^-2·U^-1·L.