Molecular imprinting glucose sensing probe system based on fiber-optic lmr sensing

Abstract

The application discloses a kind of molecular imprinting glucose sensing probe systems based on optical fiber LMR sensing, including halogen lamp light source, Y type optical fiber bundle, molecular imprinting glucose sensing probe, micro optical fiber spectrometer and host computer;The molecular imprinting glucose sensing probe is removed from inside to outside in order multimode optical fiber, ITO film layer, glucose molecular imprinting film layer, the glucose molecular imprinting film layer has imprinting hole;The ITO film layer generates LMR effect at specific thickness;Located at the imprinting hole of the glucose molecular imprinting film layer is combined with glucose molecule specifically, and the effective refractive index of glucose molecular imprinting film layer changes and causes LMR resonance wavelength change, and glucose concentration is obtained by demodulation of the change of LMR resonance wavelength.The application realizes the sensing method capable of high specificity, high sensitivity and detecting glucose.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical fiber sensors, and particularly relates to a molecular imprinting glucose sensing probe system based on optical fiber LMR sensing. BACKGROUND

[0002] In recent years, the concept of applying optical fiber surface wave sensors to glucose concentration monitoring has been proposed, which can well meet the determination of glucose due to the small volume, light weight, high sensitivity and long-distance transmission characteristics of optical fibers. The optical fiber LMR (Lossy Mode Resonance) glucose sensor has the advantages of wide source of thin film materials, simple operation, low cost and high sensitivity compared with existing optical fiber sensors. In addition, the existing optical fiber sensors are too dependent on chemical self-assembly methods, which cannot guarantee the repeatability and consistency of the preparation of the sensor film layer.

[0003] It is essential for the field to develop a simple, quick and accurate key diagnostic technology for glucose concentration monitoring. SUMMARY

[0004] In view of the technical defects of the existing optical fiber sensor, the application provides a molecular imprinting glucose sensing probe system based on optical fiber LMR sensing, which realizes the optical fiber LMR effect by using the ITO film layer to realize high-performance detection of glucose molecules.

[0005] The application realizes the following technical solutions:

[0006] A molecular imprinting glucose sensing probe system based on optical fiber LMR sensing, the system comprises a halogen lamp light source, a Y-shaped optical fiber bundle, a molecular imprinting glucose sensing probe, a miniature optical fiber spectrometer and an upper computer; wherein the molecular imprinting glucose sensing probe is connected with the halogen lamp light source and the miniature optical fiber spectrometer through the Y-shaped optical fiber bundle, and the optical signal received by the miniature optical fiber spectrometer is collected by the upper computer.

[0007] The molecular imprinting glucose sensing probe comprises, from inside to outside, a multimode optical fiber with a removed cladding, an ITO film layer and a glucose molecular imprinting film layer.

[0008] The ITO film layer generates LMR effect at a specific thickness; the imprinting holes in the glucose molecular imprinting film layer are specifically combined with glucose molecules, the effective refractive index of the glucose molecular imprinting film layer changes to cause the change of LMR resonance wavelength, and the glucose concentration is obtained by demodulating the change of LMR resonance wavelength.

[0009] A molecular imprinting glucose sensing probe, which comprises, from inside to outside, a cladding-removed multimode optical fiber, an ITO film layer and a glucose molecular imprinting film layer, wherein the glucose molecular imprinting film layer has imprinting holes.

[0010] A preparation method of a molecular imprinting glucose sensing probe based on a fiber LMR sensing, comprising the following steps:

[0011] S1: performing a multimode optical fiber pretreatment, which comprises the following steps: removing the cladding of the multimode optical fiber by using a sharp blade to expose the fiber core in a centimeter scale; sequentially cleaning the fiber core by using deionized water and alcohol; and performing end face cutting on the exposed fiber core by using a large-core fiber cutting knife to obtain a cladding-removed multimode optical fiber with a flat end face;

[0012] S2: forming an ITO film layer by sputtering, which comprises the following steps: performing a magnetron sputtering indium tin oxide film layer treatment on the sidewall of the cladding-removed multimode optical fiber, and the sputtering thickness is 400-450 nm to obtain an ITO-LMR sensing probe;

[0013] S3: preparing a glucose molecular imprinting film layer, which comprises the following steps: placing the ITO-LMR sensing probe formed in step S2 into a mixed solution of carbon quantum dots and chitosan in glacial acetic acid for film plating by pulling; then placing the sensing probe in a thermostat for drying; placing the dried sensing probe as a working electrode of a three-electrode system into a 2.0 mmol / L 3-aminobenzoic acid and 0.5 mmol / L glucose phosphate buffer solution, and performing a cyclic voltammetry scanning for 20 cycles to realize electrochemical film plating; and then immersing the sensing probe after the electrochemical film plating into a mixed solution of ethanol-acetic acid with a volume ratio of 1:1 for stirring and washing to elute the glucose template molecules, thereby obtaining a molecular imprinting glucose sensing probe;

[0014] S4: recapturing glucose molecules, which comprises the following steps: placing the molecular imprinting glucose sensing probe prepared in step S3 into a glucose solution for incubation for 30 min, and then performing detection.

[0015] The scanning range of the cyclic voltammetry in step S3 is -0.8-1.0 V, and the scanning rate is 0.1 V / s.

[0016] Compared with the traditional optical fiber probe and the preparation method thereof, the present application has the following beneficial effects and significant progress:

[0017] 1. The sensing method can detect glucose with high specificity and high sensitivity, and has the advantages of low cost and more convenient detection mode.

[0018] 2. The preparation method combined with the electrochemical film plating technology is provided, which ensures the repeatability, consistency and stability of the sensor film layer preparation, and is more efficient. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A schematic diagram of a molecularly imprinted glucose sensing probe system based on fiber-optic LMR sensing according to the present application;

[0020] Figure 2 A structural diagram of a molecularly imprinted glucose sensing probe;

[0021] Figure 3 An SEM image of a glucose molecularly imprinted membrane layer;

[0022] Figure 4 A real-time resonance wavelength shift diagram of a molecularly imprinted glucose sensing probe capturing glucose molecules;

[0023] REFERENCE NUMERALS:

[0024] 1, halogen lamp light source, 2, Y-type fiber bundle, 3, molecularly imprinted glucose sensing probe, 4, miniature fiber-optic spectrometer, 5, host computer, 6, cladding-removed multimode optical fiber, 7, ITO film layer, 8, glucose molecularly imprinted membrane layer, 9, imprinting hole. DETAILED DESCRIPTION

[0025] The present application will be further described below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to explain the present application and are not intended to limit the present application.

[0026] As shown in Figure 1 , a schematic diagram of a molecularly imprinted glucose sensing probe system based on fiber-optic LMR sensing according to the present application. The system includes a halogen lamp light source 1, a Y-type fiber bundle 2, a molecularly imprinted glucose sensing probe 3, a miniature fiber-optic spectrometer 4, and a host computer 5. Among them, the molecularly imprinted glucose sensing probe 3 is connected with the halogen lamp light source 1 and the miniature fiber-optic spectrometer 4 through the Y-type fiber bundle 2, and the optical signal received by the miniature fiber-optic spectrometer 4 is collected by the host computer 5.

[0027] As shown in Figure 2 , a structural diagram of a molecularly imprinted glucose sensing probe. The structure of the molecularly imprinted glucose sensing probe 3 includes, from inside to outside, a cladding-removed multimode optical fiber 6, an ITO film layer 7, and a glucose molecularly imprinted membrane layer 8.

[0028] As shown in Figure 3 , an SEM image of a glucose molecularly imprinted membrane layer. The glucose molecularly imprinted membrane layer 8 forms imprinting holes 9 matching the shape, size, and functional groups of the glucose template molecules.

[0029] The molecular imprinting glucose sensing probe utilizes ITO film layer to realize fiber loss mode resonance (LMR) sensing, the loss mode wave of the ITO film layer and the evanescent wave produce LMR effect at a specific thickness of the ITO film layer when the conditions of phase matching and mode field overlap are met, which is manifested as the appearance of resonance wavelength in the spectrum, and the resonance wavelength is very sensitive to the refractive index of the medium surface environment; the imprint hole on the molecular imprinting glucose sensing probe can specifically combine with the glucose molecule, when the molecular imprinting glucose sensing probe captures the glucose molecule, the effective refractive index of the glucose molecule imprinting film layer changes, thereby causing the change of LMR resonance wavelength, and the wavelength change is demodulated as the glucose concentration.

[0030] Further, the wavelength range of the halogen lamp light source 1 is 380-2400nm, and the output power is 8.8mW.

[0031] Further, the core diameter of the Y-type optical fiber bundle 2 is 400μm.

[0032] The preparation method of the molecular imprinting glucose sensing probe of the present application comprises the following process steps:

[0033] S1: multi-mode optical fiber pretreatment, the specific treatment includes: selecting multi-mode optical fiber with cladding diameter of 430μm and core diameter of 400μm, removing the cladding of the multi-mode optical fiber with a sharp blade to expose the core in centimeter level; sequentially cleaning the core with deionized water and alcohol; flattening the end face of the optical fiber with the exposed core part under the assistance of a large-core fiber cutting knife to obtain the removed cladding multi-mode optical fiber 6 with a flat end face;

[0034] S2: sputtering to form ITO film layer 7, the specific treatment includes: to excite LMR effect, the side wall of the removed cladding multi-mode optical fiber 6 is treated with magnetron sputtering indium tin oxide film layer, the sputtering thickness is 400-450nm, and the ITO-LMR sensing probe is obtained;

[0035] S3: preparing a glucose molecular imprinting film layer 8, the specific processing including: configuring an ice acetic acid solution of chitosan with a concentration of 1.5%, ultrasonically mixing a carbon quantum dot aqueous solution and the ice acetic acid solution of chitosan at a volume ratio of 3:2, placing the ITO-LMR sensing probe formed in step S2 into the mixed solution to draw film plating, and setting a drawing speed of 10 mm / min; subsequently, placing the sensing probe into a thermostat, and drying for 15 min in a 60 DEG C constant temperature environment; configuring 3-aminobenzoic acid with a concentration of 2.0 mmol / L as a functional monomer solution, and 0.5 mmol / L of glucose as a template molecule solution, both of which are solvents of a glucose phosphate buffer with a pH value of 9, and mixing them as an electrolyte for standby; taking the dried sensing probe as a working electrode of a three-electrode system, placing it into the glucose phosphate buffer, and adopting a cyclic voltammetry scanning of 20 cycles to realize electrochemical film plating until no obvious redox peak appears; immersing the sensing probe after electrochemical film plating into a mixed solution of ethanol-acetic acid with a volume ratio of 1:1 to stir and wash for 20 min to elute the glucose template molecule, and thus obtaining a molecular imprinting glucose sensing probe; at this time, imprinting holes matching the shape, size and functional groups of the glucose template molecule are formed on the surface of the molecular imprinting glucose sensing probe.

[0036] As shown in the SEM diagram of the molecular imprinting glucose sensing probe, Figure 4 imprinting holes after elution of the glucose molecules can be observed on the surface thereof;

[0037] S4: recapturing glucose molecules, the specific processing including: placing the molecular imprinting glucose sensing probe 3 prepared in step S3 into a glucose solution to incubate for 30 min, simultaneously, connecting a halogen lamp light source 1 and a micro fiber spectrum 4 through a Y-type optical fiber bundle 2, and detecting in real time through an upper computer system 5.

[0038] The scanning range of the cyclic voltammetry in step S3 is-0.8-1.0 V, and the scanning rate is 0.1 V / s.

[0039] The above-mentioned molecular imprinting glucose sensing probe preparation method utilizes the conductivity of the ITO film layer, takes the sensing probe after film plating drawing as a working electrode of a three-electrode system, combines electrochemical film plating technology, realizes efficient preparation of the molecular imprinting glucose sensing probe, and further achieves high-performance detection of glucose molecules. Moreover, benefiting from the excellent conductivity of the ITO film layer, the optical fiber after ITO film plating is taken as a working electrode of a three-electrode system, combines electrochemical film plating technology, realizes efficient preparation of the molecular imprinting glucose sensing probe, and guarantees the repeatability and consistency of the sensor film layer in the preparation process.

[0040] The working process of the molecular imprinting glucose sensing probe system based on the optical fiber LMR sensing of the application is described as follows:

[0041] The broadband light emitted by the halogen lamp light source 1 is transmitted to the molecular imprinting glucose sensing probe 3 through the Y-type optical fiber bundle 2, the molecular imprinting glucose sensing probe 3 is placed in the glucose solution, at this time the light reflected back by the molecular imprinting glucose sensing probe 3 carrying the LMR signal is transmitted to the micro fiber spectrometer 4 again through the Y-type optical fiber bundle 2, the real-time signal acquisition is carried out by the host computer 5, the detection of the glucose solution is carried out, and the obtained real-time resonance spectrum is as shown in Figure 3 It can be seen that the resonance wavelength gradually red shifts with the increase of the acquisition times, and the specific detection of the glucose molecules is realized.

[0042] When the light is transmitted to the molecular imprinting glucose sensing probe 3, the total reflection principle of the light is no longer met, the originally transmitted light in the multimode optical fiber 6 with the removed cladding layer will leak in the form of loss mode in the ITO film layer 7, and the fiber LMR effect is formed. When the imprint hole on the molecular imprinting glucose sensing probe 3 captures the glucose molecules, specific binding is formed, the medium surface refractive index is changed, and then the drift of the resonance wavelength is shown.

[0043] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it, although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some or all of the technical features can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, the non-essential improvements, adjustments or replacements made by those skilled in the art according to the content of the present application are all within the scope of the present application.

Claims

1. A molecularly imprinted glucose sensing probe system based on fiber optic LMR sensing, characterized in that, The system includes a halogen lamp light source, a Y-shaped fiber bundle, a molecularly imprinted glucose sensing probe, a miniature fiber optic spectrometer, and a host computer; wherein, the molecularly imprinted glucose sensing probe is connected to the halogen lamp light source and the miniature fiber optic spectrometer respectively through the Y-shaped fiber bundle, and the optical signals received by the miniature fiber optic spectrometer are collected by the host computer. The molecularly imprinted glucose sensing probe consists of, from the inside out, a decladding multimode optical fiber, an ITO film, and a glucose molecularly imprinted film; the ITO film has a thickness of 400-450 nm and is used to generate the LMR effect; the glucose molecularly imprinted film has imprinted pores that match the shape, size, and functional groups of the glucose template molecule. The ITO film layer generates an LMR effect at a specific thickness; the imprinted pores in the glucose molecule imprinted film layer specifically bind to glucose molecules, and the effective refractive index of the glucose molecule imprinted film layer changes, causing a change in the LMR resonance wavelength. The glucose concentration is obtained by demodulating the change in the LMR resonance wavelength.

2. A method for preparing a molecularly imprinted glucose sensing probe based on fiber optic LMR sensing, characterized in that, Includes the following steps: S1: Perform multimode fiber preprocessing, which includes: removing the cladding of the multimode fiber with a sharp blade to expose a core on the order of centimeters; cleaning the core with deionized water and alcohol in sequence; and cutting the exposed core portion of the fiber flat with the assistance of a large-diameter fiber cleaver to obtain a cladding-removed multimode fiber with a flat end face. S2: Sputtering to form an ITO film layer. The specific process includes: magnetron sputtering an indium tin oxide film layer on the sidewall of the multimode fiber after removing the cladding. The sputtering thickness is 400~450nm, and an ITO-LMR sensing probe is obtained. S3: Preparation of a glucose molecularly imprinted film, specifically including: placing the ITO-LMR sensing probe formed in step S2 into a mixed solution of carbon quantum dots and chitosan in glacial acetic acid for dip-coating; ultrasonically mixing the carbon quantum dot aqueous solution and the chitosan in glacial acetic acid solution at a volume ratio of 3:2; subsequently drying the sensing probe in a constant temperature oven; utilizing the conductivity of the ITO film, using the dried sensing probe as the working electrode of a three-electrode system, placing it in a glucose phosphate buffer solution containing 2.0 mmol / L 3-aminophenylboronic acid and 0.5 mmol / L at pH 9, and performing electrochemical coating by scanning 20 times using cyclic voltammetry; immersing the electrochemically coated sensing probe in a 1:1 volume ratio ethanol-acetic acid mixture for stirring and washing to elute glucose template molecules, thus obtaining the molecularly imprinted glucose sensing probe; S4: Recapture glucose molecules. The specific process includes: incubating the molecularly imprinted glucose sensing probe prepared in step S3 in a glucose solution for 30 minutes, and then performing real-time detection of the resonance wavelength based on fiber optic LMR sensing.

3. The method for preparing a molecularly imprinted glucose sensing probe based on fiber optic LMR sensing as described in claim 2, characterized in that, In step S3, the scanning range of the cyclic voltammetry is -0.8 to 1.0 V, and the scanning rate is 0.1 V / s.

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