Development And Preliminary Clinical Application Of Kit For Quantitative Detection Of Tyrosine In Urine

Urinary tyrosine(Tyr)is a powerful indicator for malignant tumor screening.The current detection methods may not be quantitative,or expensive,complicated operation procedures.There is an urgent need to develop more sensitive,accurate,and economical detection methods.Spectrophotometry has the advantages of simple operation,sensitive results,mature equipment conditions,and low cost.The raw materials of fluorescent nanosensors are environmentally friendly,the sensing performance is excellent,and the analysis is convenient.Therefore,in this study,two quantitative detection methods for Tyr were constructed based on spectrophotometry and fluorescent nanosensors,and they were successfully applied to urine samples.The details are as follows:1.A method based on spectrophotometry to detect Tyr in solution was successfully established.Tyr can react with 4-amino-antipyrine and potassium ferricyanide to form quinones with characteristic UV absorption at 478 nm,and the Tyr concentration in the solution can be detected.The standard curve of the Tyr detection system based on spectrophotometry showed that the absorbance value of the mixed solution had a good linear relationship with the concentration of Tyr(Tyr 0～60.0 mg/L).The linear regression equation was Y=0.0114X–0.0095,and the correlation coefficient was0.999.The precision,trueness,minimum detection limit,linearity evaluation and recovery rate of the method were evaluated,and satisfactory results were obtained.This method not only has a low detection limit(0.679 mg/L),but also can detect the concentration of Tyr in real urine samples.It also has good precision(RSD%0.94%～1.30%)and accuracy(recovery rate 95.61%～104.68%).The detection of Tyr in solution based on spectrophotometry is not only fast in detection,convenient in operation,and low in cost,but also can be applied to the existing instruments in clinical laboratories without the need to purchase additional large equipment,which can meet the requirements of large-scale malignant tumor screening.2.A fluorescent nanosensor was constructed to detect Tyr concentration in solution.The main sensing principle of the sensor is based on the excellent fluorescence performance of Nitrogen-doped Graphene Quantum dots(N-GQDs).N-GQDs were synthesized by a one-step hydrothermal method using citric acid and ammonia as precursors.The optimal fluorescence excitation wavelength was 347 nm,and the optimal fluorescence emission wavelength was 427 nm.Tyr can be oxidized by potassium periodate in solution to form quinones,and quinones can quench the fluorescence of N-GQDs by fluorescence resonance energy transfer.The change of fluorescence intensity shows a good correlation with Tyr concentration(Tyr 0～85.7mg/L).The regression equation was Y=–0.0104X~2+2.196X–0.6056,and the correlation coefficient was 0.999.The precision,trueness,minimum detection limit,linearity evaluation and recovery rate of the sensor have been evaluated,and good results have been obtained.In addition,when the nanosensor was applied to the detection of Tyr concentration in actual urine samples,good accuracy was also obtained(the recovery rate was 96.02%～104.71%).The sensor does not require large equipment,and the raw materials are cheap and easy to obtain,which has potential value in clinical application.It can be used to detect the concentration of Tyr in urine samples.