CN208860790U - A kind of l-cysteine sensor based on glutathione composite membrane grid gold electrode - Google Patents

Abstract

The utility model discloses a kind of l-cysteine sensors based on the complex film modified grid gold electrode of glutathione, the sensor includes field effect transistor, the field effect transistor is equipped with the extended gold electrode of grid, in the extended gold electrode of grid, the grid part extends the distance of 0.1-500mm, and gold electrode surfaces are assembled with glutathione composite membrane；The glutathione composite membrane is the composite membrane of dibutyl phthalate, graphene oxide and glutathione composition.The utility model will be on dibutyl phthalate/graphene oxide/glutathione (DBP/GO/GSH) composite material modification extended grid golden membranous layer of scene effect transistor, a kind of novel DBP/GO/GSH self assembly grid gold electrode (GGE) is formed, Sensitive Detection is realized to l-cysteine using field effect transistor signals in situ amplification.Its preparation process is simple and convenient, and the response time is fast, has potential application prospect.

Description

A kind of l-cysteine sensor based on glutathione composite membrane grid gold electrode

Technical field

The utility model belongs to chemical/biological field of sensing technologies, and in particular to one kind is based on glutathione composite membrane grid The l-cysteine sensor of pole gold electrode, i.e., a kind of selective membrane Copper diethlydithiocarbamate are suitable for healthy aquaculture and life science The detection of aspect.

Background technique

Dibutyl phthalate (Dibutyl phthalic, DBP) is that one kind can make product have improved flexibility Colourless oil liquid, stability, resistance to deflection, cohesiveness and waterproof performance are excellent so being used as polyvinyl acetate, alcohol The plasticizer of acid resin, NC Nitroncellulose, ethyl cellulose and neoprene, nitrile rubber.

Graphene oxide (Graphene oxide, GO) is the derivative of graphene, and structure is substantially the same with graphene, only It is to be connected with a large amount of oxygen-containing groups on the basal plane that infinitely extends of two-dimensional space that one layer of carbon atom is constituted, contains-OH in plane And C-O-O, and contain C=O and-COOH at its lamella edge.Graphene oxide has some excellent property compared with graphene Can, there are good wettability and surface-active, and play very big work on the mechanics for improving material, electric property With.

In recent years, many electrochemical research in relation to the composite modified material of graphene oxide, Ya etc. are aoxidized using N doping Graphene modified glass-carbon electrode detects the carbendazim in food, which shows excellent electrocatalytic oxidation to carbendazim Performance, detection range are 5.0-850 μ g/L, and Monitoring lower-cut is 1.0 μ g/L；Shen etc. by nickel nano material, attapulgite with And the dilute composite material modification of reduction-oxidation graphite is used to detect glucose on glass-carbon electrode, inspection of the sensor for glucose Survey shows the features such as high sensitivity and fast response, Monitoring lower-cut 0.37mM；Hadi Beitollahi etc. is in screen printing Graphene oxide/zinc oxide (GO/ZnO) composite material is modified on brush electrode to be used for while detecting levodopa and tyrosine, this Electrode shows high sensitivity to two kinds of detection substances, and highly selective, Monitoring lower-cut is respectively 4.5 × 10^-7M and 3.4 × 10^-7M；Rao etc., which has studied two on p-type nitrophenols, has electroactive functional group on the dilute modified glassy carbon electrode of reduction-oxidation graphite Electrochemical behavior, which is 0.55mM to the Monitoring lower-cut of PNP；Li Junhua etc. repairs GO/MWCNT nanocomposite It adorns on glass-carbon electrode, constructing a kind of novel L-Trp sensor that has good stability, detection range is 1.0 × 10^-6—1.0×10^-4Mol/L, Monitoring lower-cut are 3.5 × 10^-7mol/L；Liu little Hua etc. is prepared for for measuring catechol Single-walled carbon nanotube-graphene oxide composite modified glassy carbon electrode, the modified electrode have good electro-catalysis to catechol Activity, detection are limited to 4 × 10^-7M。

GSH is to be formed by glutamic acid, cysteine and glycine by peptide bond, there is the γ-COOH by glutamic acid in molecule With the α-NH of cysteine₂Special γ-the peptide bond being condensed into.Glutathione has antioxidation and integrates detoxication also The function of normal immune system can be assisted in keeping.Due to glutathione antioxidation and integrate detoxication so that its It is widely used, cannot be only used for drug, more can be used as the base-material of functional food, in anti-aging, strengthen immunity, antitumor It is widely applied in equal functional foods.

Glutathione exists in the form of two kinds in human body, and one is reduced glutathione (GSH), another kind is oxidation Type glutathione (GSSG), the reduced glutathione that the glutathione that usually we say refers to.Since glutathione contains mercapto Base, therefore glutathione can self-assemble to gold electrode surfaces by-SH.There are many self-assemble to gold about glutathione Electrode surface is used to detect the report of metal ion.Zeng etc. is by the mixture self assembly of 3- mercaptopropionic acid and glutathione in gold The surface of electrode is used to detect Cu²⁺, studies have shown that the sensor is for Cu²⁺Excellent selectivity is shown, detection range is 0.1 μM~1mM；The self assembly of MPA-GSH system is used to detect Cd in gold electrode surfaces by Chow²⁺, repeatability is good for this electrode, Monitoring lower-cut is 5nM.Decorative material of the glutathione as electrode not only has extensive effect in terms of detecting metal ion, Some nitrogen-containing molecules are being detected, are also having important role in terms of organic matter.Vilian etc. repairs RGO/L-P-GSH composite material For decorations on glass-carbon electrode, which shows excellent electrocatalysis characteristic to 4- amino phenols, and detection range is 0.4~200 μ M, Monitoring lower-cut have reached 0.03 μM (S/N=3), and selectivity is good, can be applied to the detection of actual sample；Pérez- R à fols etc. is modified on screen printing electrode carbon nano-fiber using GSH, for detecting Cd²⁺And Pb²⁺, Monitoring lower-cut difference It is 3.0 μ g/L and 3.2 μ g/L；Han etc. utilizes Fe₃O₄@Au-GSH molecularly imprinted polymer electrochemical method detects estrogen, this The detection range that sensor detects estrogen is 0.025~10 μM, and Monitoring lower-cut is 2.76 μM.

Cystine (L-cystine) is that a kind of containing disulfide bond, (sulfide linkage is exactly that two thiol molecules are connected using S -- S Come structure) amino acid.The detection method of amino acid has very much, high performance liquid chromatography (HPLC), gas chromatography-mass spectrum (GC-MS), capillary electrophoresis, fluorescence probe detection method etc..But these instrumental methods need valuableness in the prevalence of at high cost Precision instrument, complicated sample preparation process and skilled operator, and cannot online or inconvenient to carry use etc. lack Fall into, thus explore develop a kind of simple, fast amino acid analysis method be the area research important goal.With other instrument Device analysis method is compared, electrochemical method is simple with its, it is sensitive, without radiation, it is pollution-free the features such as increasingly by the pass of people Note, is used not only for laboratory testing, and can also be used in field assay.Various electrochemical techniques such as Differential Pulse Voltammetry (DPV), square wave voltammetry (SWV), electrochemical impedance spectroscopy (EIS) and fluorescence spectrophotometric method (ISEs), have been widely used for Various fields.However, the method for electric potential type electrochemical sensing detection l-cysteine is not yet reported.

Utility model content

The utility model overcomes the shortcomings of the prior art, and provides a kind of based on glutathione composite membrane grid gold electrode L-cysteine sensor.

In order to achieve the above object, technical solution provided by the utility model are as follows:

The l-cysteine sensor based on glutathione composite membrane grid gold electrode includes field effect transistor, described Field effect transistor is equipped with the extended gold electrode of grid, that is, grid gold electrode, it is described in the extended gold electrode of grid Grid part extends the distance of 0.1-500mm, and golden membranous layer (10) surface-assembled of gold electrode has glutathione composite membrane (12).

Wherein, the field effect transistor includes Si basal layer (1) and the polysilicon gate on Si basal layer (1) (7)；It is implanted into p trap (2) and N-type substrate (3) on the Si basal layer (1), is equipped with source electrode (4) and drain electrode at the p trap (2) (5), p trap (2) and N-type substrate (3) are implanted and the Si basal layer (1) for constructing active electrode (4) and drain electrode (5) is equipped with two Silicon oxide layer (6)；Successively plated on the basal layer of the polysilicon gate (7) aluminum-copper alloy layer (8), chromium palladium alloy layer (9) and Golden membranous layer (10)；Silicon nitride layer (11) are additionally provided on the basal layer of polysilicon gate (7) and silicon dioxide layer (6).The aluminium Copper alloy layer (8) with a thickness of 20-600nm, chromium palladium alloy layer (9) with a thickness of 20-600nm, the thickness of golden membranous layer (10) For 20-1000nm.

The sensor has this special response relation of good energy to l-cysteine (13), and the range of linearity is 2.5 × 10^-6— 1.0×10^-4Mol/L, response sensitivity are 55.72 ± 1.5mV/-pC (25 DEG C), and detection is limited to 1.02 × 10^-6mol/L。

The detection method of l-cysteine based on the sensor includes the following steps:

(1) p trap (2) and N-type substrate (3) are implanted on the Si basal layer (1) of scene effect transistor, using thermal evaporation and magnetic Control sputtering technology constructs source electrode (4) and drain electrode (5) at p trap (2), is then being implanted p trap (2) and N-type substrate (3) simultaneously It constructs and constructs silicon dioxide layer (6) on the Si basal layer (1) of active electrode (4) and drain electrode (5), then use thermal evaporation and magnetic control Sputtering technology successively plates aluminum-copper alloy layer (8), chromium palladium alloy layer (9) and golden membranous layer on the basal layer of polysilicon gate (7) (10), silicon nitride layer (11) finally are constructed on the basal layer of polysilicon gate (7) and silicon dioxide layer (6)；By grid part Extend the distance of 0.1-500mm, the extension grid field effect transistor with grid gold electrode is made；

(2) the grid gold electrode of the extension grid field effect transistor after cleaning is soaked in dibutyl phthalate solution In, after taking-up, by graphene oxide solution drop coating on grid gold electrode, after grid gold electrode is dry, by grid gold electrode It is soaked in glutathione solution, then cleans the grid gold electrode after impregnating, glutathione composite membrane (12) modification is made Glutathione composite membrane grid gold electrode；The glutathione composite membrane is dibutyl phthalate, graphene oxide and paddy The composite membrane of the sweet peptide composition of Guang；

(3) by reference electrode, glutathione composite membrane grid gold electrode and the electrode interface for extending grid field effect transistor Double high resistant differential amplifier circuits are connected to form, reference electrode, glutathione composite membrane grid gold electrode are inserted into PBS buffer solution In, the power interface for extending grid field effect transistor is connected with the positive and negative anodes of regulated power supply respectively, it is brilliant by gate field-effect is extended The signal output interface of body pipe is connected with the test port of universal meter, thus constitutes a complete sensing detection circuit；Benefit The signals in situ amplification of field-effect transistors, can Sensitive Detection system potential change；Paddy Guang as working electrode Sweet peptide composite membrane grid gold electrode can be intended to stablize as time increases and gradually in the current potential of PBS buffer solution, to electricity The sample to be tested for containing various concentration l-cysteine (13) is added in position after stablizing, and then obtains corresponding potential response data, complete At the detection of l-cysteine in sample to be tested (13).

Preferably, in step (1), with thermal evaporation and magnetron sputtering technique on the basal layer of polysilicon gate (7) successively When plating aluminum-copper alloy layer (8), chromium palladium alloy layer (9) and golden membranous layer (10), using Si₃N₄It is passivated；Aluminum-copper alloy layer (8) Component including following parts by weight: Al 40-68, Cu 30-60, Ni 2-12, Fe 1-8, Ti 1-6, Nb 0.01- 0.50；Chromium palladium alloy layer (9) includes the component of following parts by weight: Cr 40-80, Pd 10-40, Ni 2-12, Fe 1-8, Ti 1—6,Nb 0.01—0.50；Aluminum-copper alloy layer (8) with a thickness of 20-600nm, chromium palladium alloy layer (9) with a thickness of 20-600nm, golden membranous layer (10) with a thickness of 20-1000nm.

Preferably, it is 0.1-that dibutyl phthalate solution described in step (2), which is dibutyl phthalate concentration, The solution of 10.0mmol/L, the graphene oxide solution are the solution that graphene oxide concentration is 0.1-10.0mg/mL, institute The ethanol solution for stating glutathione is ethanol solution of the glutathione concentrations for 0.1-10.0mmol/L, the graphene oxide Solution is the solution that graphene oxide concentration is 1.0-10.0mg/mL, and the ethanol solution of the glutathione is that glutathione is dense Degree is the ethanol solution of 1.0-10.0mmol/L.It is successively to extend grid field effect with ultrapure water and washes of absolute alcohol in step (2) Answer the grid gold electrode of transistor.The time that grid gold electrode is soaked in dibutyl phthalate solution in step (2) is The dosage of graphene oxide solution drop coating graphene oxide solution when on grid gold electrode is 1.0-by 1.0-300min Grid gold electrode is soaked in the time in the ethanol solution of glutathione as 1-72h by 10.0 μ L.It is with anhydrous in step (2) Ethyl alcohol and ultrapure water clean the grid gold electrode after impregnating, and are dried, save.

Preferably, the reference electrode in step (3) is the Ag/AgCl electricity of saturated calomel electrode or built-in saturation KCl solution Pole, working electrode are glutathione composite membrane grid gold electrode.PBS buffer solution in step (3) is pH3.0-8.0, concentration For the phosphate buffer solution of 0.1mol/L, pH value is preferably 5.0, and preparation method is by a certain amount of NaH₂PO₄·2H₂O、 Na₂HPO₄·12H₂O, NaCl is dissolved in water by proper proportion mixing, adjusts its pH value using the hydrochloric acid of 0.1mol/L.

The utility model is described in further detail below:

The grid gold electrode (GGE) of field effect transistor (FET) is extended certain distance by the utility model, is such as extended 0.1-500mm modifies field using dibutyl phthalate/graphene oxide/glutathione (DBP/GO/GSH) composite material The extended grid gold electrode (GGE) of effect transistor constructs a kind of novel electric potential type electrochemical sensing for detecting l-cysteine Device.Electro-chemical test, the XPS analysis of sensing interface show modifier GSH, and two carboxyls are negatively charged in the solution, with object Electrostatic Absorption occurs so as to cause the variation of electrode surface film potential in gold electrode surfaces containing the positively charged l-cysteine of amino. The electrode has good potential response to l-cysteine in the PBS buffer solution of pH=4.0, and electrode is to the linear of l-cysteine Response range is 5.00 × 10^-6—1.00×10^-4Mol/L, response sensitivity are 54.16 ± 1.5mV/-pC (25 DEG C), detection It is limited to 1.02 × 10^-6Mol/L, response time are 76 seconds.The electrode has relatively good reproducibility and stability, and the electrode has Good selectivity, L- glycine (L-Gly), L-threonine (L-Thy), L-phenylalanine (L-Phe), Pidolidone (L- Glu), l-Alanine (L-Ala), L-Aspartic acid (L-Asp), l-Isoleucine (L-Lle), L-Histidine (L-His), L- dried meat Propylhomoserin (L-Pro), L-lysine (L-Lys), l-methionine (L-Met), L-cysteine (L-Cys) and five kinds of metals from Son such as Fe³⁺、Zn²⁺、Cu²⁺、Ca²⁺、Ni²⁺Deng the measurement for not interfering l-cysteine.In addition, the electrode can be used for practical pig blood Clearly, in pig urcine sample l-cysteine measurement, the rate of recovery illustrates that the potentiometric sensor is expected to become up to 99.5-105.7% A kind of easy, quick new tool of l-cysteine analysis.

In short, the utility model develops a kind of selective membrane electric potential type electrochemical sensor of simplicity, one kind is provided The detection method of new l-cysteine repairs dibutyl phthalate/graphene oxide/glutathione (DBP/GO/GSH) It adorns on the extended grid golden membranous layer of scene effect transistor, forms a kind of novel DBP/GO/GSH self assembly grid gold electrode (GGE), Sensitive Detection is realized to l-cysteine using field effect transistor signals in situ amplification, wherein glutathione is multiple It closes film to adsorb by electrostatic interaction in conjunction with positively charged object l-cysteine, forms double electrical layers and generate identification monovalence The film potential of organoammonium ions.Experimental results show that the sensor is 5.00 × 10 in l-cysteine concentration^-6—1.00× 10^-4This special response relation of good energy is shown within the scope of mol/L, and its preparation process is simple and convenient, the response time is fast, tool There is potential application prospect.

Detailed description of the invention

Fig. 1 is the design diagram for extending gate field effect transistor；In figure: 1, Si basal layer, 2, source electrode, 3, electric leakage Pole, 4, p trap, 5, N-type substrate, 6, silicon dioxide layer, 7, polysilicon gate, 8, aluminum-copper alloy layer, 9, chromium palladium alloy layer, 10, gold Film layer, 11, silicon nitride layer, 12, glutathione composite membrane；

Fig. 2 is the identification response theory schematic diagram of DBP/GO/GSH molecule combination l-cysteine molecule；In figure: 10, golden film Layer, 12, glutathione composite membrane, 13, l-cysteine；

Fig. 3: Fig. 3 A and Fig. 3 B be respectively electrode in potassium ferricyanide solution (containing 2.0mmol/L K₃[Fe(CN)₆], 2.0mmol/L K₄[Fe(CN)₆], 0.2mol/L Na₂SO₄) in AC impedance figure and cyclic voltammogram；In Fig. 3 A and Fig. 3 B: A, GGE, b, GGE/DBP/GO/GSH, c, GGE/DBP/GO/GSH/L-cystine；

Fig. 4 is the full spectrogram of XPS on Different electrodes surface；In figure: a, GGE, b, GGE/DBP/GO/GSH, c, GGE/DBP/ GO/GSH/L-cystine；

Fig. 5 be the complex film modified GGE electrode of DBP/GO/GSH glutathione slope with pH variation (pH 3.0,3.5, 4.0,4.5,5.0,5.5,6.0,6.5,7.0) relational graph；

Fig. 6 is GGE/DBP/GO/GSH electrode in the PBS buffer solution of pH=4.0, in conjunction with various concentration l-cysteine The potential response curve graph obtained afterwards；

Fig. 7: Fig. 7 A is that various concentration L- Guang is added in GGE/DBP/GO/GSH electrode in the PBS buffer solution of pH=4.0 When m- current potential dynamic curve diagram after propylhomoserin；Fig. 7 B is that l-cysteine (10 is added^-4Mol/L the dynamic response curve figure after)；

Fig. 8 is influence of the common amino acid to GGE/DBP/GO/GSH electrode detection l-cysteine.

Specific embodiment

One, experimentation

1, the preparation of DBP/GO/GSH self-assembled film gold electrode

The preparation process of DBP/GO/GSH self-assembled film: ultrapure water and ethyl alcohol cleaning electrode are first successively used；Then GGE is soaked Bubble 1h in the DBP solution of 1mmol/L；Electrode is taken out after 1h, then 5 μ L of graphene oxide (1mg/mL) solution drop coating exists On electrode；After pole drying, it is immersed in the GSH/ ethanol solution of 1mmol/L；The GGE that finally self-assembled film is modified It takes out and is saved with ethyl alcohol and ultrapure water cleaning, drying, obtain the self-assembled film gold electrode of composite material.

2, extend the design of gate field effect transistor and the preparation of grid gold electrode

Fig. 1 is the schematic diagram for extending gate field effect transistor, in conjunction with metal-oxide semiconductor fieldeffect transistor (MOSFET) basic structure is implanted into p trap 2 and N-type substrate 3 on the Si basal layer 1 of scene effect transistor, using thermal evaporation and Magnetron sputtering technique constructs source electrode 4 and drain electrode 5 at p trap 2, is then being implanted p trap 2 and N-type substrate 3 and is constructing active Silicon dioxide layer 6 is constructed on the Si basal layer 1 of electrode 4 and drain electrode 5, then using thermal evaporation and magnetron sputtering technique in polysilicon Aluminum-copper alloy layer 8, chromium palladium alloy layer 9 and golden membranous layer 10 are successively plated on the basal layer of grid 7, finally in polysilicon gate 7 Silicon nitride layer 11 is constructed on basal layer and silicon dioxide layer 6；Aluminum-copper alloy layer 8 includes the component of following parts by weight: Al 40- 68,Cu 30—60,Ni 2—12,Fe 1—8,Ti 1—6,Nb 0.01—0.50；Chromium palladium alloy layer 9 includes following parts by weight Component: Cr 40-80, Pd 10-40, Ni 2-12, Fe 1-8, Ti 1-6, Nb 0.01-0.50；Aluminum-copper alloy layer 8 With a thickness of 20-600nm, chromium palladium alloy layer 9 with a thickness of 20-600nm, golden membranous layer 10 with a thickness of 20-1000nm；It will The gold electrode of grid part extends the distance of 200mm, and utilizes SiO₂And Si₃N₄It is passivated field effect transistor chip, it is therefore an objective to It prevents part of the chip in addition to Au from contacting with solution, extends gate field effect transistor (EGFET) to be formed.To EGFET's Extend grid gold electrode (GGE) film surface and carry out different physical/chemical moditied processings, forms sensitive membrane to realize to mesh to be measured Mark the Sensitive Detection of object.Gluathione is made by the self assembly of glutathione composite membrane on the surface of grid gold electrode by preceding method The glutathione composite membrane grid gold electrode that peptide composite membrane 12 is modified.

3, the test of self-assembled film grid gold electrode

The electrode potential test phosphate buffer solution (PBS, 0.1mol/L) that buffer system is pH3.0-8.0, matches Method processed is by a certain amount of NaCl, NaH₂PO₄·2H₂O and Na₂HPO₄·12H₂O is dissolved in water by proper proportion mixing, uses The hydrochloric acid of 0.1mol/L adjusts its pH value.Firstly, by the good grid gold electrode (GGE) of calomel electrode, self assembly and this laboratory The extension gate field effect transistor (EGFET) of design is connected to form double high resistant differential amplifier circuits, inserts electrodes into PBS buffering In solution, the power interface of EGFET is connected with the positive and negative anodes of regulated power supply respectively, the survey of signal output interface and universal meter It tries port to be connected, thus constitutes a complete sensing detection circuit.Using the signals in situ amplification of field effect transistor, Can Sensitive Detection system potential change.Working electrode GGE can as time increases and gradually in the current potential of PBS buffer solution It is intended to stablize, determinand l-cysteine is added after current potential is stablized, and then obtain corresponding potential response data.

Two, experimental result and analysis

1, the Response Mechanism and electrochemical Characterization of GGE/DBP/GO/GSH electrode

Glutathione (GSH) is a kind of a kind of substance containing sulfydryl end group, and the sulphur in sulfydryl can form Au- with Au S key and self assembly on golden plate electrode surface, the carboxyl of glutathione it is free go out H⁺And in negatively charged and l-cysteine- NH₃ ⁺Between electrostatic attraction occurs, so as to cause the variation of film potential；And glutathione contain there are two-COOH, and l-cysteine contains There are two amino, a glutathione molecules combine a l-cysteine molecule, therefore are in the response characteristic of monovalence cation, It is as shown in Figure 2 to respond identification process.

For the interaction of checking carrier and l-cysteine, the utility model uses AC impedance and cyclic voltammetric method The electrochemical behavior of above-mentioned different modifying electrode is investigated, as shown in Figure 3.Fig. 3 is exchange of the electrode in potassium ferricyanide solution Impedance diagram (A) and cyclic voltammogram (B).A represents naked gold electrode in Fig. 3 A, impedance value very little, and b represents DBP-GO-GSH in Fig. 3 A The gold electrode of composite material modification, compared with naked gold electrode, there is small semicircle and illustrates that impedance value becomes larger in high frequency section, and illustrates this Composite material reduces the electric conductivity of gold electrode.In conjunction with l-cysteine (1.0 × 10^-5Mol/L after), the semicircle of high frequency section becomes Greatly, illustrate that impedance value is increased again (as shown in curve c in Fig. 3 A), this is because suction-operated, drop occur for GSH and l-cysteine Low electronic conductivity, so that the gold electrode impedance value for having modified GSH increases, the variation tendency of impedance also can be from corresponding Cycle voltammetry behavior (Fig. 3 B) in be confirmed.

A represents naked gold electrode in Fig. 3 B, there is apparent oxidation peak and reduction peak, illustrates pretreated naked gold electrode transmitting Electronic capability is stronger.B represents the gold electrode of DBP-GO-GSH composite material modification in Fig. 3 B, and redox peaks are compared with naked gold electrode It is small much compared to obvious, illustrate that this composite material forms nonconducting unimolecule self assembly by sulfydryl on a gold surface Film layer hinders [Fe (CN)₆]^3-/4-It is conducted in the electronics of electrode surface.Combining l-cysteine (1.0 × 10^-5Mol/L after), Redox peaks (as shown in curve c in Fig. 3 B) reduce again, this is because having modified on the gold electrode of composite material again Continue to have adsorbed cystine, reduce electronic conductivity, to reduce electrochemical transduction electric current, illustrates that DBP-GO-GSH is compound The gold electrode and l-cysteine of material modification have good coordination combination, show identification of this method for l-cysteine Detection is feasible.

2, the XPS characterization of GGE/DBP/GO/GSH electrode

Using x-ray photoelectron spectroscopy (XPS) to the interaction situation between modified electrode and object ion done into One pacing is taken temperature sign, and the full spectrogram of XPS on above-mentioned Different electrodes surface is as shown in Figure 4.As shown in Figure 4, (bent compared to naked gold electrode Line a), after having modified DBP-GO-GSH gold electrode (curve b) combination can be 162.71eV at there is the characteristic peak of S2p, Show the electrode surface composite material successfully self assembly in gold electrode surfaces.Curve c represents GGE/DBP/GO/ Surface XPS map after GSH electrode detection l-cysteine, modified electrode react l-cysteine after carbon, oxygen element and The peak intensity of element sulphur is above the peak intensity for reacting preceding electrode, and different atomic binding energy data can be found that O1s's from table 1 0.31eV is changed in conjunction with that can survey before and after l-cysteine, has been that there are electrostatic adsorptions with l-cysteine due to glutathione, makes It obtains electronegative GSH originally and has adsorbed positively charged l-cysteine, so it, which is combined, to deviate to low energy.The combination of S2p can be To high energy offset by 0.93eV after detection l-cysteine, this is because-the COOH on GSH slough hydrogen and with-NH₃ ⁺Electrostatic occurs to inhale Draw causes its combination that can increase so as to cause the cloud density reduction of S.From table 2 it is also seen that before electrode combination l-cysteine The variation of C, O, S element highest CPS can also prove that the effect of Electrostatic Absorption has occurred so that electrode table in GSH and l-cysteine afterwards Face is changed.

The different atomic binding energies of table 1

The not homoatomic highest CPS of table 2

3, the selection of Optimal pH

Experiment has studied electrode under the conditions of pH is 3.0,3.5,4.0,4.5,5.0,5.5,6.0,6.5,7.0 respectively, electricity Electrode potential with tested solion concentration variation relation, and find out according to this can this special response slope, then make slope and pH Relational graph, as shown in Figure 5.As can be seen from Figure 5: electrode response maximum slope when pH=4.0, and its slope value is 55.72 ± 1.5mV/-pC (25 DEG C), the theoretical value of this special response slope close to energy.This explanation, when pH=4.0, electrode response is most It is good, so that obtaining optimal pH value is 4.0.

4, GGE/DBP/GO/GSH Responsibility of the electrode

Experiment exam test response performance of the electrode to l-cysteine, Fig. 6 are that PBS buffering of the electrode in pH=4.0 is molten In liquid, in conjunction with the potential response curve graph obtained after various concentration l-cysteine.As seen from the figure, with the increasing of l-cysteine concentration Add, electrode potential is also gradually increased, and illustrates that the l-cysteine of modified electrode surface bond increases, and the electrode is pH=4.0's It is 2.5 × 10 to the linear response range of l-cysteine ion in PBS buffer solution^-6mol/L—1.0×10^-4mol/L.Together When, using Least Square in Processing, electrode potential linear response figure is obtained after being fitted, the linear equation of electrode is Δ E= 324.40+55.72log₁₀C.Its detection limit can be obtained according to graphing method, and value is about 1.02 × 10^-6mol/L.It is responded Slope is nernst theory response slope value of the 55.72mV/-pC close to monovalence cation, further proves to speculate before us A glutathione molecules combine a l-cysteine molecule reasonability.

5, the measurement of response time, stability and reproducibility

Response time and the stability of DBP/GO/GSH composite material modified gold electrode detection l-cysteine have been investigated in experiment. Fig. 7 A is the when m- current potential dynamic response figure being added after various concentration l-cysteine in PBS buffer solution, by 1.0 × 10^-6—1.0×10^-4Its current potential changed over time is continuously measured and recorded within the scope of mol/L from low concentration to high concentration Value, it can be seen that in entire concentration range electrode reach balance reaction time it is very short, to reach potential response maximum value 95% calculates response time, as 76s, shows that the electrode can have cracking response speed to l-cysteine；Fig. 7 B is to add again Enter 10^-4Dynamic response curve after mol/L l-cysteine, the response performance for further demonstrating the electrode are stablized.By the electricity Extremely to 1.0 × 10^-5Mol/L l-cysteine sample follow-on test 35 days, response slope variation was 45.36mV/-pC, was had dropped 18.59%, illustrate that the potentiometric sensor about can be used 1 month or more, service life is longer.

The reproducibility of 3 GGE/DBP/GO/GSH electrode of table

The experiment exam electricity of GGE/DBP/GO/GSH composite material modified electrode combination various concentration l-cysteine sample Position response reproducibility, i.e., to 1 × 10^-5Mol/L and 1 × 10^-4The l-cysteine standard items of mol/L measure their current potential back and forth Value respectively surveys 10 times (as shown in table 3).By the analysis and processing of data, it is found that relative standard deviation is respectively 1.39% He 2.45%, and relative standard deviation is smaller, illustrates that reproducibility of the electrode in the l-cysteine of two various concentrations is preferable.

6, the selectivity of electrode

One of key property of ion selective electrode is exactly that its selectivity is good, is only had to a certain specific substance There is response.Therefore, in the PBS buffer solution of the pH=4.0 containing modified electrode, 10 μM of l-cysteine, chaff interferent is added Concentration is 10 times of test substance concentration, i.e., 100 μM, wherein examining L- glycine (L-Gly), L-threonine (L-Thy), L- Phenylalanine (L-Phe), Pidolidone (L-Glu), l-Alanine (L-Ala), L-Aspartic acid (L-Asp), l-Isoleucine (L-Lle), L-Histidine (L-His), L-PROLINE (L-Pro), L-lysine (L-Lys), l-methionine (L-Met), L- Cysteine (L-Cys) and five metal ion species such as iron, zinc, copper, calcium, nickel plasma (shown in Fig. 8).The result shows that removing L- Other 17 kinds of interfering substances except cysteine are unobvious to the interference of test substance l-cysteine, it may be said that the bright sensing Device has good selectivity.

7, the measurement of the rate of recovery and analysis are applied

In the case where optimizing experiment condition, using DB/GO/GSH composite material modification grid gold electrode to L- Guang in actual sample Propylhomoserin concentration is measured.When measurement, actual sample Swine serum 1,2 is acquired respectively and pig urcine 3,4 is centrifuged, supernatant is taken, uses The PBS buffer solution that pH is 4.0 dilutes 10 times, and the l-cysteine that known concentration is added in the sample is measured by standard addition method For the rate of recovery between 99.5-105.7%, experimental result illustrates that the electrode can be used for the detection of l-cysteine in actual sample.

In short, the utility model provides a kind of electrodes selective modified based on DBP/GO/GSH and extend grid golden film, The experimental results showed that the electrode shows highly sensitive energy in the PBS buffer solution of pH=4.0, to l-cysteine, this is special Response relation, linear response range are 2.5 × 10^-6—1.0×10^-4Mol/L, detection are limited to 1.02 × 10^-6mol/L.The electricity The pole response time is short (about 76 seconds), and has good selectivity, reproducibility and the features such as stability.In addition, the electrode energy For the detection of the l-cysteine in actual sample, it is expected to the novel means as on-line checking l-cysteine.

Claims (3)

1. a kind of l-cysteine sensor based on glutathione composite membrane grid gold electrode, the sensor includes field-effect crystalline substance Body pipe, the field effect transistor are equipped with the extended gold electrode of grid, which is characterized in that the extended gold electrode of grid In, the grid part extends the distance of 0.1-500mm, and golden membranous layer (10) surface-assembled of gold electrode has glutathione compound Film (12)；The glutathione composite membrane is the composite membrane of dibutyl phthalate, graphene oxide and glutathione composition.

2. sensor as described in claim 1, which is characterized in that the field effect transistor includes Si basal layer (1) and sets In the polysilicon gate (7) on Si basal layer (1)；P trap (2) and N-type substrate (3), the p are implanted on the Si basal layer (1) It is equipped with source electrode (4) and drain electrode (5) at trap (2), be implanted p trap (2) and N-type substrate (3) and constructs active electrode (4) and leakage The Si basal layer (1) of electrode (5) is equipped with silicon dioxide layer (6)；Successively plated aluminum on the basal layer of the polysilicon gate (7) Copper alloy layer (8), chromium palladium alloy layer (9) and golden membranous layer (10)；In the basal layer and silicon dioxide layer (6) of polysilicon gate (7) On be additionally provided with silicon nitride layer (11).

3. sensor as claimed in claim 2, which is characterized in that the aluminum-copper alloy layer (8) with a thickness of 20-600nm, Chromium palladium alloy layer (9) with a thickness of 20-600nm, golden membranous layer (10) with a thickness of 20-1000nm.