Method and sensor for detecting l-cysteine based on 3,3′-dithiobis (1-propanesulfonate)-mercury composite membrane

A method for detecting L-cysteine based on a 3,3′-dithiobis (1-propanesulfonate)-mercury composite membrane, comprising the following steps:

• (1) implanting a p-well and an N-type substrate on a Si substrate of a field effect transistor, constructing a source electrode and a drain electrode at the p-well by a thermal evaporation and a magnetron sputtering, then constructing a silicon dioxide layer on the Si substrate after being implanted with the p-well and the N-type substrate and constructed with the source electrode and the drain electrode, followed by successively plating an aluminum-copper alloy layer, a chromium-palladium alloy layer and a gold film layer on a substrate of a polysilicon gate by the thermal evaporation and the magnetron sputtering, and next, constructing a silicon nitride layer on the substrate of the polysilicon gate and the silicon dioxide layer;
• subsequently, extending a gate part of the polysilicon gate by a distance of 0.1-500 mm to obtain an extended gate field effect transistor with a gate gold electrode;
• (2) preparing an ethanol solution of disodium 3,3′-dithiobis (1-propanesulfonate), cleaning the gate gold electrode of the extended gate field effect transistor, soaking the gate gold electrode of the extended gate field effect transistor in the ethanol solution of disodium 3,3′-dithiobis (1-propanesulfonate) in a dark and dry environment, and putting the ethanol solution of disodium 3,3′-dithiobis (1-propanesulfonate) aside at 25° C., then taking out and washing the gate gold electrode of the extended gate field effect transistor, followed by soaking the gate gold electrode of the extended gate field effect transistor in an ethanol solution of mercuric nitrate, putting the ethanol solution of mercuric nitrate aside, and then washing the gate gold electrode of the extended gate field effect transistor after being soaked to obtain a 3,3′-dithiobis (1-propanesulfonate)-mercury composite membrane gate gold electrode modified by a 3,3′-dithiobis (1-propanesulfonate)-mercury composite membrane;
• and
• (3) connecting an electrode interface of a reference electrode, an electrode interface of the 3,3′-dithiobis (1-propanesulfonate)-mercury composite membrane gate gold electrode, and an electrode interface of the extended gate field effect transistor to form a differential amplifier circuit with a high input impedance, inserting the reference electrode and the 3,3′-dithiobis (1-propanesulfonate)-mercury composite membrane gate gold electrode into a phosphate buffer solution (PBS), and connecting power interfaces of the extended gate field effect transistor to positive and negative poles of a stabilized voltage supply, respectively, connecting a signal output interface of the extended gate field effect transistor to a test port of a multimeter to form a complete sensing detection circuit;
• wherein a potential change of a system is detected sensitively by using an in-situ signal amplification of the extended gate field effect transistor;
• potential of the 3,3′-dithiobis (1-propanesulfonate)-mercury composite membrane gate gold electrode as a working electrode tends to be stable with an increase of time in the PBS, and after the potential is stable, samples to be tested containing different concentrations of L-cysteine are added, and then corresponding potential response data corresponding to the samples to be tested are obtained to complete a detection of L-cysteine in the samples to be tested.