CN105044178A - Chiral recognition to tryptophan enantiomer containing zinc ion by chiral sensor based on chitosan/sodium alginate - Google Patents

Abstract

The invention relates to the chiral recognition of tryptophan enantiomers containing zinc ions by a chitosan/sodium alginate-based chiral sensor. Include the following steps: prepare chitosan-modified glassy carbon electrode (CS/GCE), prepare chitosan/sodium alginate modified electrode (CS/SA/GCE), to Zn(II)-L-/D-Trp identify. The beneficial effects of the present invention are: the prepared CS/SA modified electrode is simple to operate, time-saving and pollution-free, and the results show that the CS/SA modified glassy carbon electrode has an efficient recognition ability. The potential difference of Zn(II)-L-/D-Trp can reach 136mV.

Description

Chiral recognition of tryptophan enantiomers containing zinc ions by a chitosan/sodium alginate based chiral sensor

technical field

The invention relates to electrodepositing chitosan (CS) on a glassy carbon electrode, and then self-assembling sodium alginate (SA) to obtain a CS/SA/GCE modified electrode, and adopting DPV to Zn(II)-L-/D-Trp The invention provides selective recognition and belongs to the fields of electrochemical sensors and molecular recognition.

Background technique

Chiral compounds are closely related to the life process. Different chiral isomers have obvious differences in biological activities, pharmacological effects, and metabolic processes in organisms. Popular directions for analysis. In recent years, the research on chiral sensors has achieved rapid development. Among them, electrochemical sensors have extensive research value for identifying chiral substances due to their advantages of simple preparation, low cost, and high recognition efficiency.

Polysaccharides are natural macromolecular compounds composed of monosaccharides, which widely exist in plants, animals and microbial tissues, and have various important functions. Carbohydrates have anti-inflammatory, anti-virus, anti-radiation, nucleic acid biosynthesis and other biopharmaceutical values. Recently, sugars have developed rapidly in supramolecular chemistry. For example, Tao Yongxin et al. modified natural β-cyclodextrin on poly-L-glutamic acid, and carried out electrochemical and rapid recognition of L/D-tryptophan. L/D-color The oxidation peak current ratio of amino acid reached 2.30; YukiMatsuoka et al. designed a DNA-chitosan ultrafiltration membrane for chiral separation of phenylalanine, and found that D-phenylalanine preferentially passed through the ultrafiltration membrane, etc. This opens up new avenues for the identification of chiral compounds. Chitosan has good adsorption, film-forming and permeability, fibrillation, hygroscopicity and moisture retention. There are many hydroxyl groups, amino groups, and some N-acetylamino groups distributed on the chitosan macromolecular chain, which will form various intramolecular and intermolecular hydrogen bonds, and at the same time make chitosan ionic to many ions, organic substances, and biomolecules. Chitosan and its derivatives can be used as chiral recognition materials due to the functions of exchange, ion chelation, and adsorption. Sodium alginate is a natural polysaccharide with good film-forming properties, and its composite materials have been widely used as food additives. Recently, SA and APTES silane have been reported to selectively separate phenylalanine isomers by molecularly imprinted hybrid membranes, suggesting the potential application of SA in chiral recognition. Water, amino acids, polysaccharides, and metal ions play a pivotal role in the life activities of the human body and animals. They interact with each other and affect the whole life system together. Therefore the present invention adopts electrodeposition chitosan (CS) on the glassy carbon electrode, then self-assembles sodium alginate (SA), obtains CS/SA/GCE modified electrode, adopts differential pulse voltammetry (DPV) to (Zn(II) )-L-/D-Trp) for selective recognition, revealing the relationship between them.

Contents of the invention

In view of the characteristics in the background technology, the object of the present invention is to selectively recognize Zn(II)-L-/D-Trp by chitosan/sodium alginate modified glassy carbon electrode (CS/SA/GCE).

The technical scheme adopted by the present invention to solve its technical problems is: electrodeposit CS on the glassy carbon electrode, then self-assemble SA, obtain the glassy carbon electrode (CS/SA/GCE) modified electrode modified by chitosan/sodium alginate, adopt DPV selectively recognizes Zn(II)-L-/D-Trp. Include the following steps:

a. Preparation of chitosan-modified glassy carbon electrode (CS/GCE): prepare CS solution (solvent: 0.1-0.3M HCl, pH=1.0-2.0), and deposit on the surface of glassy carbon electrode by constant potential to obtain CS/GCE modification electrode.

b. Preparation of CS/SA/GCE modified electrode: the CS/GCE modified electrode prepared in step a was placed in SA solution (pH=6.4) for 18-36 hours to obtain CS/SA/GCE modified electrode.

c. Identification of Zn(II)-L-/D-Trp: use differential pulse method to identify L-/D-Trp, and place the CS/SA/GCE modified electrode prepared in step b in 20-30mL Zn (II) In -L-/D-Trp solution (standing time 300s ~ 1200s), DPV was performed within the electrochemical window range of 0.4V ~ 1.0V (vs. SCE) at a scan rate of 0.1 ~ 0.5V/s After each measurement, the modified electrode was subjected to repeated potential scanning in 20-30mL blank solution (0.1-0.3MKClpH=6.4) until it was stable, and the electrode activity was restored.

Further, the concentration of CS in step a is 2-3 g/L.

Further, the deposition potential in step a is -0.3-0.7V.

Further, the deposition time in step a is 90-210s.

Further, the concentration of SA in step b is 1.8-2.2 g/L.

Further, the concentration of Zn(II) in step c is 0.04-0.06mM.

Further, the concentration of L-/D-Trp in step c is 0.1-0.5 mM.

The beneficial effects of the present invention are: the present invention provides a chitosan/sodium alginate-based chiral sensor, which is mainly through the constant potential deposition of chitosan on the surface of a glassy carbon electrode, and then self-assembled sodium alginate To prepare the sensor, the preparation method is simple, the raw materials are cheap and easy to obtain, safe and non-toxic, and the detection sensitivity is high. For chiral recognition, the sensor only needs to be immersed in the amino acid solution configured with supporting electrolyte for a period of time, and then the chiral recognition result is obtained through electrochemical detection, which is simple to operate, saves time, and has high detection sensitivity. The chiral sensor of the invention can efficiently identify tryptophan isomers containing Zn(II). Experiments show that the chiral sensor has an efficient recognition ability for Zn(II)-L-/D-Trp, and its oxidation peak potential difference can reach 136mV.

Description of drawings

The experiment will be further described below in conjunction with the accompanying drawings.

FIG. 1 is a cyclic voltammogram of each modified electrode in Example 1.

Fig. 2 is the influence of the standing time on the recognition efficiency in the second embodiment.

Fig. 3 is the effect of the pH of Zn(II)-L-/D-Trp on the recognition efficiency in Example 3.

FIG. 4 shows the effect of the content of L-Trp on the recognition efficiency in Example 4.

Fig. 5 shows the effect of the CS/SA/GCE modified electrode on the recognition of L-/D-Trp with or without Zn(II) in Comparative Example 1.

Detailed ways

The present invention will now be further described in conjunction with specific examples, and the following examples are intended to illustrate the present invention rather than further limit the present invention.

Embodiment one:

(1) Prepare chitosan (CS) solution (solvent is 0.1M HCl), deposit CS on the surface of glassy carbon electrode by constant potential, the deposition voltage is -0.3～-0.7V, and the deposition time is 150s to obtain CS/GCE modification electrode.

(2) Put the electrode prepared in step 1 in the SA solution for 18-36 hours to obtain a CS/SA/GCE modified electrode.

(3) The electrodes prepared in steps 1 and 2 were placed in a potassium ferricyanide solution, and characterized by cyclic voltammetry, with a potential range of -0.2 to 0.6 V and a scan rate of 0.1 v/s.

Embodiment two:

In order to investigate the differences in the recognition of Zn(II)-L-/D-Trp by CS/SA/GCE modified glassy carbon electrodes under different standing times. Therefore, respectively adopt the standing time of 150s, 300s, 450s, 600s, 900s, 1200s to carry out the identification of Zn(II)-L-/D-Trp, the results are shown in Figure 2, it can be seen that when the standing time is 600s, The recognition efficiency is the largest.

Embodiment three:

In order to investigate the differences in the recognition of Zn(II)-L-/D-Trp by CS/SA/GCE modified glassy carbon electrodes at different pH. Therefore, adjust the pH to be 3, 5, 7, 9, and 11 respectively, and carry out the recognition of Zn(II)-L-/D-Trp. The results are shown in Figure 3. As the pH increases, the peak potential difference is greater, and the pH reaches At 7.0, the peak potential difference is greater, and then the peak potential decreases as the pH increases, and then reaches equilibrium. When the pH is 3-6, tryptophan is positively charged, positively repelling the amino groups on Zn(II) and CS, and the potential is small; while when the pH is 6-11, Zn(II)-Trp and SA/CS Ligand exchange occurs, resulting in an increase in potential, pH>7, and the adsorption of L-/D-Trp on the modified electrode increases simultaneously, and the potential changes little, reaching equilibrium.

Embodiment four:

In order to investigate the application of CS/SA/GCE modified electrode in Zn(II)-L-/D-Trp solution. In the mixed system of L-/D-Trp, different potentials are obtained by changing the content of L-Trp, so as to fit a linear equation, we use 0%, 10%, 30%, 40%, 50%, 60% , 80%, and 100% L-Trp solutions, the results are shown in Figure 4. Through the linear equation, we can basically determine the content of L-Trp and D-Trp in the mixed system.

Comparative example one:

(1) Prepare the CS/SA/GCE modified electrode according to step 2 of Example 1, put the electrode in the L-/D-Trp solution for 600s, and sweep the electrode at 0.4V~1.0 at a sweep rate of 0.1~0.5V/s DPV was performed within the electrochemical window of V (vs. SCE). After each measurement, the modified electrode was subjected to repeated potential scanning in 25mL blank solution (0.1MKClpH=6.4) to stabilize and restore the electrode activity.

The results are shown in Figure 5. We can see that the CS/SA/GCE modified electrode has a better ability to recognize the tryptophan enantiomer containing zinc ions. Because CS/SA can form coordination compounds with Zn(II) and tryptophan, Zn(II) is conducive to ligand exchange with CS/SA to form a quaternary coordination system, thereby improving its recognition ability.

Claims (4)

1. glass-carbon electrode substrates shitosan (CS), self assembly sodium alginate (SA) again, obtain CS/SA/GCE modified electrode, adopt differential pulse voltammetry (DPV) to carry out Selective recognition to Zn (II)-L-/D-Trp, step is as follows:

A, prepare chitosan-modified glass-carbon electrode (CS/GCE): preparation CS solution (solvent is 0.1 ~ 0.3MHCl, pH=1.0 ~ 2.0), adopt potentiostatic electrodeposition in glassy carbon electrode surface, obtain CS/GCE modified electrode.

B, preparation CS/SA/GCE modified electrode: the CS/GCE modified electrode prepared in step a is rested on 18 ~ 36h in SA solution (pH=6.4), obtains CS/SA/GCE modified electrode.

C, identification to Zn (II)-L-/D-Trp: adopt differential pulse method to identify Tryptophan enantiomer, CS/SA/GCE modified electrode obtained in step b is rested in 20 ~ 30mLZn (II)-L-/D-Trp solution (time of repose 300s ~ 1200s), within the scope of the electrochemical window of 0.4V ~ 1.0V (vs.SCE), carry out DPV with the speed of sweeping of 0.1 ~ 0.5V/s, surveyed rear modified electrode at every turn and swept in 20 ~ 30mL blank solution (0.1 ~ 0.3MKClpH=6.4) and surely recover electrode activity.

2. glass-carbon electrode substrates CS according to claim 1, self assembly SA again, obtain CS/SA/GCE modified electrode, DPV is adopted to carry out Selective recognition to Zn (II)-L-/D-Trp, it is characterized in that: in described step a, the concentration of CS is 2 ~ 3g/L, sedimentation potential is-0.3 ~-0.7V, and sedimentation time is 90 ~ 210s, and temperature of reaction is 25 ~ 30 DEG C.

3. glass-carbon electrode substrates CS according to claim 1, self assembly SA again, obtain CS/SA/GCE modified electrode, DPV is adopted to carry out Selective recognition to Zn (II)-L-/D-Trp, it is characterized in that: in described step b, the concentration of SA is 1.8 ~ 2.2g/L, temperature of reaction is 25 ~ 30 DEG C.

4. glass-carbon electrode substrates CS according to claim 1, self assembly SA again, obtain CS/SA/GCE modified electrode, DPV is adopted to carry out Selective recognition to Zn (II)-L-/D-Trp, it is characterized in that: in described step c, the concentration of Zn (II) is 0.04 ~ 0.06mM, the concentration of L-/D-Trp is 0.1 ~ 0.5mM, and temperature of reaction is 25 ~ 30 DEG C.