CN105301066A - Electrospun nanofiber chitosan capacitive sensor used for detecting kanamycin - Google Patents

Abstract

The invention relates to an electrospun nanofiber chitosan capacitive sensor for detecting kanamycin, which consists of a glassy carbon electrode coated with an insulating film layer on the surface and a kanamycin molecule coated on the surface of the glassy carbon electrode Nanofiber chitosan film layer composition. The nanofiber chitosan imprinted with kanamycin molecules is prepared by mixing and stirring the template molecule kanamycin and chitosan in an organic solvent, electrospinning to prepare nanofiber chitosan, and then eluting In addition to the template molecule kanamycin, dry the obtained. The electrospun nanofiber chitosan capacitive sensor of the invention can realize high sensitivity and high selectivity detection of kanamycin. The entire invention process is simple in operation, low in cost, short in detection time, good in stability, meets actual needs, is successfully applied to actual sample detection, is environmentally friendly, and is convenient for expanding production.

Description

Electrospun nanofiber chitosan capacitive sensor for detection of kanamycin

technical field

The invention belongs to the field of capacitive sensors, in particular to an electrospun nanofiber chitosan capacitive sensor for detecting kanamycin and a method for detecting kanamycin.

Background technique

Kanamycin is a commonly used aminoglycoside antibiotic. Similar to other aminoglycoside antibiotics, it has a relatively low safety residue limit and can cause many side effects, such as hearing loss, kidney toxicity and drug allergy . In addition, kanamycin is widely used in agriculture, aquaculture, and animal husbandry, and is often used as a feed additive to accelerate the growth and development of animals. However, the antibiotics left in animal products will seriously endanger human health after long-term consumption by humans. At present, many analytical methods are used for the detection of kanamycin, such as: high performance liquid chromatography, microbial method, resonance Rayleigh scattering method, spectrophotometry, electrochemical method and so on. Among them, the electrochemical method has developed rapidly due to the advantages of simple device, rapid detection, high sensitivity, and low cost. The current reported literature methods include: based on nanoparticles, graphene and thionine. Label-free immune sensors, based on water-soluble graphene/ Prussian blue-chitosan/nanoporous composite material immune sensor, based on visible light active C ₃ N ₄ and graphite oxide nanocomposite photoelectrochemical aptabody sensor, etc. Capacitive molecular imprinted sensors respond to changes in the thickness of the insulating layer or the dielectric properties of the surface, and are widely used due to the advantages of no need for labeling and low detection limits.

Electrospinning technology has been widely used in the field of preparing nanofibers in recent years. It is an effective method for preparing submicron fibers. Many polymers have been spun into non-woven fiber films, oriented fiber bundles and three-dimensional structures by electrospinning. Fibrous scaffolds, these nanofibers have the characteristics of large surface area and high porosity, and have been successfully used in medicine, sensors, batteries and capacitors and other fields. The electrospinning device is mainly composed of a high-voltage power supply, a container with a small nozzle and a receiving device. The basic principle is: the polymer solution or melt forms an electrostatic jet stream under the action of an external high-voltage electrostatic field force, and forms nanofibers after drying. After applying an electric field between the end of the syringe and the collecting plate, the surface charge changes the polymer droplet from a spherical to a conical shape. When the field strength exceeds the critical value, that is, when the electrostatic repulsion force of the surface charge overcomes the surface tension, the charged jet ejects, and the interaction between the charge density and the internal field strength has reached equilibrium. The high surface charge density creates a "whip" in which the jet bends to form highly stretched polymer fibers with rapid evaporation of the solvent.

Contents of the invention

The technical problem to be solved in the present invention is to use cheap chitosan as the detection material, and construct a new type of electrospun nanofiber chitosan capacitive sensor for detecting kanamycin by introducing kanamycin imprinting molecules .

In order to solve the problems of the technologies described above, the technical scheme adopted in the present invention is as follows:

An electrospun nanofiber chitosan capacitive sensor for the detection of kanamycin, which consists of a glassy carbon electrode coated with an insulating film layer and nanofibers coated with kanamycin molecules imprinted on the surface of the glassy carbon electrode Chitosan film layer composition.

The nanofiber chitosan imprinted with kanamycin molecules is prepared by mixing and stirring the template molecule kanamycin and chitosan in an organic solvent, electrospinning to prepare nanofiber chitosan, and then eluting In addition to the template molecule kanamycin, dry the obtained.

According to the above scheme, the mass ratio of the template molecule kanamycin to chitosan is 1:2-1:4.

The preparation method of above-mentioned electrospun nanofiber chitosan capacitive sensor, comprises the following steps:

1) Electrode insulating film construction: o-phenylenediamine was electroplated on the surface of a clean glassy carbon electrode to obtain poly-o-PD/GCE;

2) The template molecule kanamycin and chitosan are mixed and stirred and dissolved in an organic solvent, and nanofiber chitosan is prepared by electrospinning, then the template molecule kanamycin is eluted and dried to obtain imprinted kanamycin The nanofiber chitosan with kanamycin molecule was formulated into a dispersion solution, coated on the surface of poly o-PD/GCE, and dried at room temperature to obtain molecularly imprinted chitosan. Electrospun nanofiber chitosan glassy carbon electrode, denoted as molecularly imprinted CS/poly-o-PD/GCE.

According to the above scheme, the step 1) is to dissolve o-PD (o-phenylenediamine) and electrolyte KCl in PBS solution to prepare a PBS solution of o-PD, and then use this as electrolyte, and use cyclic voltammetry , electroplating poly-o-phenylenediamine on the surface of glassy carbon electrodes to obtain poly-o-PD/GCE.

According to the above scheme, the PBS solution of o-PD in the step 1) is 0.1MPBS solution of 10mMo-PD (pH=7.0), and the experimental parameters of cyclic voltammetry are: voltage range 0-0.8V, scan speed 4 -6mV/s, scan 8-12 circles.

According to the above scheme, the preparation method of the nanofiber chitosan imprinted with kanamycin molecules is as follows: dissolving chitosan in TFA and DCM solutions, then adding kanamycin, stirring overnight, to obtain electrospun Then use a syringe pump to inject the electrospinning solution from the syringe for electrospinning. The anode of the high-voltage generator is connected to the end of the syringe, and the cathode is connected to the collecting plate with aluminum foil. The collected electrospinning fibers are dried at room temperature Overnight to remove TFA and the moisture that may be contained after spinning. After the drying is complete, soak it in saturated sodium carbonate solution overnight to neutralize the excess acid. Finally, use 5% dilute hydrochloric acid solution and water to treat the template molecules. Repeated elution and drying.

According to the above scheme, the volume ratio of TFA and DCM is 7:3, the electrospinning voltage is 15-18KV, the needle of the syringe is 20-22, and the flow rate of the electrospinning liquid is 1-1.2mL/h.

According to the above scheme, the mass volume concentration of chitosan in the electrospinning system is 0.02-0.04 g/mL.

According to the above scheme, in the step 2) the concentration of the nanofiber chitosan imprinted with kanamycin molecules is 0.8-1.2 mg/mL.

The application of the above-mentioned electrospun nanofiber chitosan capacitive sensor in the detection of kanamycin content, the application method:

(3) Soak the electrospun nanofiber chitosan capacitive sensor, that is, the molecularly imprinted CS/poly-o-PD/GCE electrode, in the solution to be tested containing the target kanamycin molecule for a period of time, then take it out and put it into the solution containing In the PBS electrolyte solution, a saturated calomel electrode was used as a reference electrode, a platinum electrode was used as a counter electrode, and a modified glassy carbon electrode was used as a working electrode. Electrochemical AC impedance spectroscopy (EIS) was used with an amplitude of 10mV and a frequency of 0.1HZ. Time Z "value, according to formula C ₌ -1/(2πfZ"), calculate and obtain C value, compare this capacitance value with the capacitance value C of soaking in the solution to be tested without kanamycin, calculate and obtain this kanamycin Relative capacitance change of mycin molecularly imprinted CS/poly o-PD/GCE, relative capacitance change=(CC ₀ )/C ₀ ;

(4) Calculate and obtain the content of kanamycin in the sample solution to be tested based on the standard curve of relative capacitance change and kanamycin concentration value obtained in advance.

According to the above scheme, the PBS electrolyte solution is a 0.1M PBS electrolyte solution with pH=7.

According to the above scheme, the soaking time of the molecularly imprinted CS/poly-o-PD/GCE in the test solution containing the target molecule kanamycin is at least 15 minutes, preferably 15 minutes.

According to the above scheme, the method of obtaining the standard curve of the capacitance change and the concentration of kanamycin: prepare a series of concentration of kanamycin solutions, put the molecularly imprinted CS/poly-o-PD/GCE on the card of each concentration Soak in namycin solution for a period of time, then take it out and put it into the electrolyte solution containing PBS, use saturated calomel electrode as reference electrode, platinum electrode as counter electrode, use electrochemical impedance spectroscopy, amplitude 10mV, determine the frequency When it is 0.1HZ, measure its Z", according to the formula C=-1/(2πfZ"), calculate and obtain the C value, and compare the capacitance value with the capacitance value C ₀ that has not been soaked in the kanamycin solution to be tested , calculate the relative capacitance change of kanamycin solutions with different concentrations, relative capacitance change=(CC ₀ )/C ₀ ;

The standard curve c(x,y)—x is the concentration of kanamycin and y is the relative capacitance change is obtained by fitting to obtain the standard curve c(x, y) of the relative capacitance change and the concentration of the kanamycin solution.

According to the above scheme, the fitting is a segmented fitting, and the linear relationship curve c ₁ (x ₁ , y ₁ )——x ₁ kanamycin solution concentration value of the relative capacitance change and the concentration of kanamycin solution is respectively obtained when the concentration is small The concentration of mycin, 0.1-100ng/ml, y ₁ is the relative capacitance change, and the linear relationship curve c ₂ (x ₂ , y ₂ )——x ₂ Kanamycin concentration, _100-500ng /ml, y2 is the relative capacitance change;

Correspondingly, when calculating the concentration of kanamycin in the sample to be tested, the linear relationship curve _c between the relative capacitance change and the concentration of the kanamycin solution when a small concentration is selected is determined according to the relative capacitance change in the sample solution to be tested (x ₁ , y ₁ ), or the linear relationship curve c ₂ (x ₂ , y ₂ ) of the relative capacitance change and the concentration of the kanamycin solution at a large concentration, and then combine the relative capacitance change of the sample solution to be tested Calculate the concentration of kanamycin in the sample to be tested.

The working mechanism of the invention is as follows: the capacitive sensor is developed based on the electric double layer theory. When any substance is adsorbed or bound to the surface of the dielectric layer, its thickness or dielectric properties will change, causing a change in the capacitance of the detection system. The present invention cleverly combines electrospinning technology and molecular imprinting technology, adopts electrospinning technology, uses trifluoroacetic acid (TFA) and dichloromethane (DCM) as spinning solvents, and uses kanamycin as template molecule, The chitosan nanofiber of kanamycin molecularly imprinted has been successfully produced, thus obtained the CS/poly o-PD/GCE (i.e. the sensor electrode of the present invention) modified molecularly imprinted, and constructed a kanamycin-sensitive A capacitive sensor based on molecularly imprinted-electrospun chitosan nanofibers with high selectivity and high sensitivity. Molecular imprinting has a special memory function for template molecules. Once the target molecule kanamycin is introduced into the system, the sensing interface can perform molecular recognition and adsorption according to predetermined selectivity and high recognition performance. The invention introduces the imprinted molecule kanamycin, based on the specific combination of the kanamycin molecule and the chitosan nanofiber, and establishes a highly sensitive and highly selective molecularly imprinted capacitive sensor. After the sensor of the present invention is soaked in the solution containing kanamycin for a period of time, the kanamycin will be adsorbed on the electrode surface, causing the thickness of the dielectric layer to increase, resulting in a decrease in capacitance. With the change of kanamycin concentration, the capacitance will change regularly. Moreover, the capacitance change of the electrode has a linear relationship with the concentration of kanamycin molecules within a certain range. Thus, a standard curve can be drawn by measuring the relative capacitance change under different concentrations of kanamycin standard solutions. Furthermore, for the unknown concentration of kanamycin, the corresponding concentration value was found from the standard curve through the measured relative capacitance change, so as to establish a new type of electrospun nanofiber chitosan capacitive sensor with high sensitivity and high selectivity. . At the same time, in the actual samples, the sensor also showed good anti-interference ability and stability.

Effect and advantage of the present invention:

1. The present invention combines electrospinning technology and molecular imprinting technology to obtain molecularly imprinted nanofiber chitosan material, and it is modified to the surface of glassy carbon electrode electroplated with poly o-PD, and the obtained electrospun nanofiber shell The polysaccharide capacitive sensor can specifically recognize kanamycin. When kanamycin is specifically recognized with this material, the thickness of the electrode dielectric layer will increase, resulting in a change in capacitance, thereby achieving high kanamycin. Sensitive, highly selective detection.

2. The entire invention process is simple in operation, low in cost, short in detection time, good in stability, meets actual needs, is successfully applied to actual sample detection, is environmentally friendly, and is convenient for expanding production.

Description of drawings

FIG. 1 is a SEM image of the electrospun nanofiber chitosan material prepared in Example 1. FIG.

FIG. 2 is an IR diagram of the electrospun nanofiber chitosan material prepared in Example 1. FIG.

FIG. 3 is a static contact angle diagram of the electrospun nanofiber chitosan material prepared in Example 1. FIG.

Fig. 4 is a synthesis diagram of an electrochemical insulating layer on the electrode surface of the present invention.

Fig. 5 is a Bode diagram of detection parameters for determining the capacitance of the present invention.

Fig. 6 is the impedance response signal of the electrospun CS/poly o-PD/GCE obtained in Example 1 for the detection of different concentrations of kanamycin.

Fig. 7 is the relationship between the relative capacitance change of electrospun CS/poly o-PD/GCE to kanamycin and its concentration obtained in Example 1.

Fig. 8 is the application of the electrospun CS/poly o-PD/GCE obtained in Example 1 in actual sample detection.

detailed description

The content of the invention of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Example 1

Preparation of electrospun nanofiber chitosan capacitive sensor for detection of kanamycin, the preparation steps include:

1) Grinding and cleaning of glassy carbon electrodes: Grinding the glassy carbon electrodes through 1.0, 0.3 and 0.05 μm alumina suspensions in sequence. After polishing, the electrode was placed in absolute ethanol and secondary distilled water for five minutes, and finally dried under nitrogen atmosphere for later use.

2) Construction of electrode insulating film: 0.745g KCl and 0.108go-PD were dissolved in 100mL 0.1MPBS solution to prepare 0.1MPBS (pH=7.0) with 10mMo-PD. By means of cyclic voltammetry, o-phenylenediamine was electroplated onto the surface of the clean glassy carbon electrode obtained in step 2). The experimental parameters are: voltage range 0-0.8V, scan speed 5mV/s, scan ten circles. It can be seen from Figure 4 that the oxidation of o-phenylenediamine is an irreversible process. In the first lap of scanning, a wide anodic oxidation peak appeared between 0-0.8V, and the peak current was almost zero from the second lap of scanning. This indicates that a tight insulating film was successfully constructed on the electrode surface.

3) Preparation of nanofiber chitosan imprinted with kanamycin molecules: 0.6g chitosan was dissolved in 20mL trifluoroacetic acid (TFA) and dichloromethane (DCM) (V/V=7:3) solution, Then add 0.2g kanamycin and stir overnight to obtain the electrospinning solution. Use a syringe pump (LSP-1B) to continuously inject the electrospinning solution from the syringe at a speed of 1.2mL/h for spinning. It is No. 22, and the voltage used in the experiment is 18KV. The anode of the high-voltage generator is connected to the end of the syringe, and the cathode is connected to the collecting plate with aluminum foil. The collected electrospun fibers were dried overnight at room temperature, and soaked in saturated sodium carbonate solution overnight after drying was complete. Finally, the template molecule was repeatedly eluted with 5% hydrochloric acid solution and water, and dried for use.

4) The nanofiber chitosan imprinted with kanamycin molecules in step 3) is characterized by SEM as shown in Figure 1, and it can be seen from Figure 1 that nanofiber chitosan with a large specific surface area has been successfully synthesized. Figure 2 is the IR characterization of nanofiber chitosan imprinted with kanamycin molecules. In the figure a, b and c are the nanofiber chitosan imprinted with kanamycin molecules before and after elution of kanamycin and separately Infrared absorption peak of kanamycin. Comparing a and b, the -OH absorption peak shifts to a lower wave number due to the formation of hydrogen bonds between kanamycin and chitosan molecules before elution. In addition, after elution, the absorption peaks of some kanamycin molecules disappeared and weakened obviously. In Figure 3, a is a bare glassy carbon sheet, and b is nanofibers after modification of kanamycin and elution. Since the nanofibers are hydrophobic, the contact angle increases. When kanamycin is combined with elution After debonding, the contact angle of the nanofibers is significantly reduced as shown in Figure c, mainly because the chitosan of the nanofibers has a certain enrichment effect on kanamycin, and the kanamycin molecule contains a large number of hydroxyl hydrophilic functional groups .

5) The nanofibrous chitosan imprinted with kanamycin molecules prepared in step 3) was formulated into a 1.0 mg/mL dispersion, and 15 μL was coated on the surface of molecularly imprinted CS/poly-o-PD/GCE, at room temperature After drying, the molecularly imprinted nanofiber molecularly imprinted chitosan electrode was obtained, which was denoted as CS/poly-o-PD/GCE, and the electrode was sealed and preserved for later use.

Application of electrospun nanofiber chitosan material to detect kanamycin sensor:

(1) Soak the molecularly imprinted CS/poly-o-PDGCE in step 4) in the solution to be tested containing the target kanamycin molecule at a concentration of 100ng/mL for 15min, then take it out and put it into the electrolyte solution containing PBS. The electrolyte solution is 0.1M PBS electrolyte solution with pH=7. A saturated calomel electrode was used as a reference electrode, a platinum electrode was used as a counter electrode, and a modified glassy carbon electrode was used as a working electrode. Electrochemical alternating current impedance spectroscopy (EIS) is used, the frequency range is set to 0.1-10000HZ, and the amplitude is 10mV. According to the Bode diagram of impedance versus frequency and phase angle versus frequency as shown in Figure 5, when the AC frequency is less than 10000 Hz, the impedance curve is a straight line with a slope close to -1, indicating that the detection system circuit is similar to the Randle circuit model. When the frequency is between 0.1 and 1000Hz, the phase angle is close to 90°, indicating that the detection system is close to an ideal capacitor under this condition. Therefore, in the detection process, choose 0.1Hz as the working frequency.

(2) Prepare a series of concentrations of kanamycin solutions (0, 0.1, 1, 5, 10, 30, 60, 100, 200, 300, 400 and 500ng.mL ^-1 ), put CS/poly-o-PD/GCE in the card of each concentration Soak in the namycin solution for 15 minutes, then take it out and put it into the electrolyte solution containing PBS, the electrolyte solution is 0.1M PBS electrolyte solution with pH=7. A saturated calomel electrode was used as a reference electrode, a platinum electrode was used as a counter electrode, and a modified glassy carbon electrode was used as a working electrode. Use electrochemical impedance spectroscopy (EIS) with an amplitude of 10mV to determine the value of Z" when the frequency is 0.1HZ. According to the formula C=-1/(2πfZ"), calculate the value of C. Compare this capacitance value with the capacitance value _C0 without kanamycin to be tested, and calculate the relative capacitance change of this kanamycin molecularly imprinted CS/poly o-PD/GCE, and the relative capacitance change = (CC ₀ )/C ₀ .

Impedance response signals of kanamycin detected by molecular imprinted CS/poly o-PD/GCE in different kanamycin solutions are shown in Figure 6, in which al corresponds to 0, 0.1, 1, 5, 10, 30, 60, 100, 200, 300, 400 and Impedance response value at the concentration of kanamycin of 500ngmL ^-1 . The figure shows the law that the impedance value increases with the increase of the concentration, which is in line with the experimental principle of the capacitive sensor.

(2) Take the concentration of each kanamycin as the abscissa, and the relative capacitance change of the molecularly imprinted CS/poly-o-PD/GCE for different concentrations of kanamycin solutions as the ordinate, and obtain the relative capacitance change by fitting The standard curve c(x, y)-x is the concentration of kanamycin, and y is the relative capacitance change, as shown in Figure 7. For the unknown concentration of kanamycin, we can find out the corresponding concentration value from the standard curve through the measured relative capacitance change.

5) In order to further confirm the practical value of the sensor, we carried out the detection of spiked recovery on the actual sample. The samples were tap water and milk. And the milk is pretreated before testing. The pretreatment process is as follows: Take 4g of the milk sample to be tested, add 15mL of phosphoric acid aqueous solution, place it on a shaker and shake for 8min; The duration is 8 minutes; the supernatant after centrifugation is taken and filtered several times, and finally the pH of the solution is adjusted to 7.

Add kanamycin to milk samples 1, 2, 3 and water samples ¹ , 2, 3 to prepare a series of milk solutions containing kanamycin at concentrations of 0, 50, 100, and 200 ng. Concentration of 0, 50, 100, 200ng.mL ^-1 tap water.

The electrospun nanofiber molecularly imprinted chitosan electrode, denoted as CS/poly-o-PD/GCE, was soaked in unspiked and spiked actual samples for 15 min, and then taken out and then put into the electrolyte solution containing PBS. The electrolyte solution is 0.1M PBS electrolyte solution with pH=7. A saturated calomel electrode was used as a reference electrode, a platinum electrode was used as a counter electrode, and a modified glassy carbon electrode was used as a working electrode. Use electrochemical impedance spectroscopy (EIS) with an amplitude of 10mV to determine the value of Z" when the frequency is 0.1HZ. According to the formula C=-1/(2πfZ"), calculate the value of C. The capacitance value is compared with the capacitance value C ₀ without soaking in the actual sample solution, and the relative capacitance change is calculated, and the relative capacitance change=(CC ₀ )/C ₀ . Calculate the concentration of corresponding solution kanamycin according to the linear equation of Fig. 7 again, finally calculate recovery rate and relative standard deviation, the result is shown in Fig. 8, the recovery rate of kanamycin is between 96.38% to 107.9%, relative standard The deviations are between 1.01% and 3.3%, which shows that the method can be applied to practical detection.

Example 2

Preparation of electrospun nanofiber chitosan capacitive sensor for detection of kanamycin, the preparation steps include:

(1) Referring to step 1) and step 2) of Example 1, prepare a glassy carbon electrode whose surface is covered with an insulating film layer.

(2) Preparation of nanofiber chitosan imprinted with kanamycin molecules: 0.6g chitosan was dissolved in 15mLTFA and DCM (V/V=7:3) solution, then 0.3g kanamycin was added, Stir overnight to obtain the electrospinning solution, and use a syringe pump (LSP-1B) to continuously inject the electrospinning solution from the syringe at a speed of 1mL/h for spinning. The needle of the syringe is No. 20, and the voltage used in the experiment is 16KV. The anode of the high voltage generator is connected to the end of the syringe, and the cathode is connected to the collecting plate with aluminum foil. The collected electrospun fibers were dried overnight at room temperature, and soaked in saturated sodium carbonate solution overnight after drying was complete. Finally, the template molecule was repeatedly eluted with 5% hydrochloric acid solution and water, and dried for use.

SEM and IR characterization of the nanofiber chitosan imprinted with kanamycin molecules in step 3) indicated that the nanofiber chitosan imprinted with kanamycin molecules was successfully synthesized in this example.

(3) The prepared nanofiber chitosan imprinted with kanamycin molecules is made into a dispersion solution and coated on the surface of molecularly imprinted CS/poly o-PD/GCE, and dried at room temperature to obtain molecularly imprinted nanofibers. The fibrous molecularly imprinted chitosan electrode, denoted as CS/poly-o-PD/GCE, was sealed and preserved for later use. The recovery rate of the sensor for kanamycin was between 91.38% and 105.1%, and the relative standard deviation was between 1.51% and 3.42%, which indicated that the method could be applied to practical detection.

Claims (10)

1. for detecting the electro spinning nano fiber shitosan capacitance type transducers of kanamycins, it is characterized in that: it is covered with insulating film layer glass-carbon electrode by surface is made up of the nanofiber shitosan rete of kanamycins molecule with the trace being coated in glassy carbon electrode surface, described trace has the nanofiber shitosan of kanamycins molecule to be template molecule kanamycins and shitosan mix and blend are dissolved in organic solvent, electrospun nanofibers shitosan, then wash-out removes template molecule kanamycins, and drying obtains.

2. the electro spinning nano fiber shitosan capacitance type transducers for detecting kanamycins according to claim 1, is characterized in that: the mass ratio of described template molecule kanamycins and shitosan is 1:2-1:4.

3. the preparation method of electro spinning nano fiber shitosan capacitance type transducers according to claim 1, is characterized in that: comprise the following steps:

1) electrode insulating film builds: at the glassy carbon electrode surface plating o-phenylenediamine of cleaning, obtain poly-o-PD/GCE;

2) template molecule kanamycins and shitosan mix and blend are dissolved in organic solvent, electrospun nanofibers shitosan, then wash-out removes template molecule kanamycins, drying obtains the nanofiber shitosan that trace has kanamycins molecule, the nanofiber shitosan of kanamycins molecule is had by trace to be made into dispersion liquid, be coated in poly-o-PD/GCE surface, at room temperature dry, namely obtain the electro spinning nano fiber shitosan glass-carbon electrode based on molecular engram, be designated as molecular engram CS/poly-o-PD/GCE.

4. the preparation method of electro spinning nano fiber shitosan capacitance type transducers according to claim 3, it is characterized in that: described step 1) for o-PD and electrolyte KCl is dissolved in PBS solution the PBS solution being mixed with o-PD, then electrolytic solution is made with this, utilize cyclic voltammetry, poly-o-phenylenediamine is electroplated onto glassy carbon electrode surface, obtains poly-o-PD/GCE;

Described step 2) in the trace concentration that has the nanofiber shitosan of kanamycins molecule to be made into dispersion liquid be 0.8-1.2mg/mL.

5. the preparation method of electro spinning nano fiber shitosan capacitance type transducers according to claim 3, it is characterized in that: described trace has the preparation method of the nanofiber shitosan glass-carbon electrode of kanamycins molecule to be: be dissolved in by shitosan in TFA and DCM solution, add kanamycins again, stirring is spent the night, obtain electrostatic spinning liquid, then with syringe pump electrostatic spinning liquid outpoured from syringe and carry out electrostatic spinning, the anode of high pressure generator is connected with injector tip, negative electrode is connected with the collecting board with aluminium foil, the electrospun fibers dry overnight at room temperature collected is with the moisture that may contain after removing TFA and spinning, to be dried completely after, place it in soaked overnight in saturated sodium carbonate liquor, neutralize excessive acid, finally with 5% dilute hydrochloric acid solution and water, wash-out is repeatedly carried out to template molecule, dry and obtain.

6. the preparation method of electro spinning nano fiber shitosan capacitance type transducers according to claim 5, it is characterized in that: the volume ratio of described TFA and DCM is 7:3, electrostatic spinning voltage is 15-18KV, and the syringe needle of syringe is No. 20-22, and the flow velocity of electrostatic spinning liquid is 1-1.2mL/h.

7. the preparation method of electro spinning nano fiber shitosan capacitance type transducers according to claim 3, is characterized in that: in electrostatic spinning system, the mass body volume concentrations of shitosan is 0.02-0.04g/mL.

8. the application of electro spinning nano fiber shitosan capacitance type transducers according to claim 1 in kanamycins content detection, is characterized in that: application process:

(1) electro spinning nano fiber shitosan capacitance type transducers and molecular engram CS/poly-o-PD/GCE electrode are immersed in a period of time in the solution to be measured containing target kanamycins molecule, then put into containing PBS electrolyte solution again after taking out, take saturated calomel electrode as contrast electrode, platinum electrode is to electrode, glass-carbon electrode after modification is working electrode, adopt electrochemical alternate impedance spectrum method (EIS), amplitude 10mV, Z " value when determining that frequency is 0.1HZ, according to formula C=-1/ (2 π fZ "), C value is tried to achieve in calculating, by this capacitance with soak capacitance C without kanamycins solution to be measured ₀compare, calculate the relative capacity variable quantity of this kanamycins molecular engram CS/poly-o-PD/GCE, relative capacity variable quantity=(C-C ₀)/C ₀,

(2) based on the typical curve of the relative capacity variable quantity obtained in advance and kanamycins concentration value, the content of trying to achieve kanamycins in testing sample solution is calculated.

9. the preparation method of electro spinning nano fiber shitosan capacitance type transducers according to claim 3, is characterized in that: described PBS electrolyte solution is the PBS electrolyte solution of the 0.1M of pH=7;

Described molecular engram CS/poly-o-PD/GCE soak time in containing the solution to be measured of target molecule kanamycins is at least 15min;

The preparation method of the typical curve of relative capacity variable quantity and kanamycins concentration value: the kanamycins solution preparing a series of concentration, molecular engram CS/poly-o-PD/GCE is placed in the kanamycins solution of each concentration and soaks a period of time, then put into containing PBS electrolyte solution again after taking out, take saturated calomel electrode as contrast electrode, platinum electrode is to electrode, adopt electrochemical alternate impedance spectrum method, amplitude 10mV, when determining that frequency is 0.1HZ, measure its Z ", according to formula C=-1/ (2 π fZ "), C value is tried to achieve in calculating, by this capacitance and the capacitance C soaked without kanamycins solution to be measured ₀compare, calculate the relative capacity variable quantity of the kanamycins solution of variable concentrations, relative capacity variable quantity=(C-C ₀)/C ₀,

Typical curve c (x, y)-x that matching obtains relative capacity variable quantity and kanamycins solution concentration value is kanamycins concentration, and y is relative capacity variable quantity.

10. the preparation method of electro spinning nano fiber shitosan capacitance type transducers according to claim 1, is characterized in that: described in fit to piecewise fitting, the linear relationship curve c of relative capacitance change and kanamycins solution concentration value when obtaining small concentration respectively ₁(x ₁, y ₁)---x ₁kanamycins concentration, 0.1-100ng/ml, y ₁for relative capacity variable quantity, the linear relationship curve c of capacitance change relative to during large concentration and kanamycins solution concentration value ₂(x ₂, y ₂)---x ₂kanamycins concentration, 100-500ng/ml, y ₂for relative capacity variable quantity;

Correspondingly, ask calculate kanamycins concentration in testing sample time, according to the linear relationship curve c of capacitance change relative when relative capacity variable quantity is determined to select small concentration in testing sample solution and kanamycins solution concentration value ₁(x ₁, y ₁), or the linear relationship curve c of relative capacitance change and kanamycins solution concentration value during large concentration ₂(x ₂, y ₂), the relative capacity variable quantity then in conjunction with this testing sample solution calculates kanamycins concentration in testing sample.