Study Of Amperometric Sarcosine Biosensor With Strong Anti-interference Capabilities

According to the latest statistics,among the top 10 cancers that affect men’s health globally,the incidence（second）and mortality（fifth）of prostate cancer（PCa）are very high,so the early detection of PCa is of great significance for reducing mortality and improving the quality of life for patients.In 2009,Sreekumar and co-workers found that sarcosine in serum or urine was related to the aggressive behavior of PCa,suggesting that sarcosine might be a biomarker.Due to the very low concentration of sarcosine and the presence of many interfering substances（ascorbic acid,uric acid,etc.）in the human body,its detection method becomes complicated.Compared with large-scale mass spectrometry detection instruments,electrochemical biosensors are a simple and low-cost device.However,when the concentration of the analyte is in the micro-molar range,the anti-interference coating（Nafion or Chitosan）commonly used cannot eliminate the interference signals generated by the co-existing electroactive interference substances,and it is easy to output a distorted current signal.Therefore,we hope to improve the resistance of sarcosine biosensors to interfering substances and develop a simple,fast and accurate electrochemical sarcosine biosensor.This is of great significance for the detection of low concentrations of sarcosine in urine or plasma,which is helpful for the rapid screening,prediction and diagnosis of PCa.The specific work we do is as follows:1.Amperometric sarcosine biosensor based on platinum-loaded mesoporous nickel phosphonateIn this work,we describe a simple strategy for the preparation of sarcosine biosensor based on platinum-loaded mesoporous nickel phosphonate（Pt/MNP）.The prepared Pt/MNP have slit holes formed by stacking,and the pore diameter distribution is mostly 8-24 nm.It is estimated that Pt/MNP has a large specific surface area(283 m² g^-1).In addition,the average pore size（BJH）and pore volume（BJH）are 16.038 nm and 0.537 cm³ g^-1 respectively.The prepared sarcosine biosensor based on Pt/MNP has good electrochemical response to sarcosine,with a linear detection range of 5-40μM,a detection limit of 0.24μM（S/N=3）,and a sensitivity of 123.51μA m M^-1 cm^-2.In addition,the Pt/MNP-based sarcosine biosensor has also shown good anti-interference performance in real serum sample tests.2.Amperometric sarcosine biosensor based on platinum-loaded mesoporous molybdenum phosphonateIn this section,we introduce a simple strategy for constructing an amperometric sarcosine biosensor with strong anti-interference ability,which is based on platinum-loaded mesoporous molybdenum phosphonate（Pt/OIHMMP）.The Pt/OIHMMP-based sarcosine biosensor has high sensitivity(16.35μA m M^-1,231.5μA m M^-1 cm^-2),low limit of detection（0.13μM）and wide linear range（1-70μM）.It achieves sensitive detection of low concentration of sarcosine in serum,corresponding to patients with benign prostatic hyperplasia（1-3μM）.At the same time,we also found that the surface potential of the carrier nanomaterials may play an important role in excluding anionic interference.Taking the anti-interference test results of 100μM ascorbic acid as an example,when using Nafion and Chitosan as the anti-interference film under the same conditions,the residual interference signals from ascorbic acid were 17.36%and24.38%,respectively,and the residual interference signal from Pt/OIHMMP-modified was only3.21%.In addition,the sarcosine biosensor has also shown good performance in real serum physiological sample tests.3.Amperometric sarcosine biosensor based on electrochemical co-deposition of manganese phosphate and poly（3,4-Ethylenedioxythiophene）@poly（Indole-6-carboxylic Acid）Based on the test results in Chapters 1 and 2,we believe that the charge density has a greater influence on the anti-interference performance.To confirm this,we conducted a confirmatory test.In this section,we introduce a simple microwave-assisted method for the synthesis of manganese phosphate（Mn PO₄）,and then platinum nanoparticles were loaded onto Mn PO₄ by the impregnation reduction method.Finally,the Pt/Mn PO₄,3,4-ethyleneoxythiophene（EDOT）and indole-6-carboxylic acid（IA）were co-deposited on a glassy carbon electrode（GCE）to prepare an amperometric sarcosine biosensor.Under optimized conditions,SOx/PEDOT-IA/Pt/Mn PO₄/GCE has a wide linear range（1-55μM）and lower limit of detection（0.11μM）,and a lower apply potential（0.25 V vs.SCE）.Taking ascorbic acid（AA）as an example,the response current signal of bare GCE to 100μM AA is defined as 100%.When Nafion and Chitosan were used as anti-interference films under the same conditions,the residual interference signal from AA was 19.74%and 27.56%,respectively,while the residual interference signal from AA was only 6.91%when modified PEDOT-IA/Pt/Mn PO₄.Compared with Nafion and Chitosan,the co-deposited PEDOT-IA/Pt/Mn PO₄ has better anti-interference ability.In addition,we found that the surface charge density is positively related to the anti-interference ability,which shows that changing the surface charge density has a positive effect on enhancing the anti-interference ability of the biosensor.