CN110554014B - Molecular imprinting fluorescence optical fiber sensor, construction method thereof and fluorescence detection method - Google Patents
Molecular imprinting fluorescence optical fiber sensor, construction method thereof and fluorescence detection method Download PDFInfo
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Abstract
The invention discloses a molecularly imprinted fluorescent optical fiber sensor, a construction method thereof and a fluorescence detection method, wherein the sensor comprises a laser light source, a Y-shaped optical fiber, a quartz optical fiber, a flange adapter and an optical fiber spectrometer, the laser light source, the Y-shaped optical fiber and the optical fiber spectrometer are sequentially connected, the quartz optical fiber modifies a gel film containing molecularly imprinted microspheres, and the Y-shaped optical fiber and the quartz optical fiber are connected through the flange adapter; laser emitted by the laser source is transmitted to the gel film on the quartz optical fiber through the Y-shaped optical fiber, and a fluorescence signal of the gel film is reflected back to the Y-shaped optical fiber and is transmitted to the optical fiber spectrometer through the Y-shaped optical fiber. The sensor is detachable, so that the optical fiber probe can be replaced, multi-target rapid detection can be respectively carried out on site, the sensor can be applied to on-site rapid monitoring of antibiotics in environmental water, and the sensing film modified by the optical fiber probe can be easily damaged after the use is finished, so that the optical fiber probe can be recycled, and unnecessary resource waste is reduced.
Description
Technical Field
The invention relates to a molecularly imprinted fluorescent optical fiber sensor, a construction method thereof and a fluorescence detection method, and belongs to the field of detection of antibiotics in a water environment.
Background
In recent years, with the rapid development of light technology, various light sensors (FOS) have come into play. This is because FOS has several major advantages: first, FOS is characterized by miniaturization. The sensing part is flexible and light, has good space adaptability and biocompatibility, and is suitable for real-time and on-line monitoring of clinical medicine, organisms and various environmental water bodies; secondly the FOS has the advantages of wide monitoring object and great flexibility. Particularly, the development of sensing membrane technologies such as a molecular imprinting membrane, a polymer membrane, a Sol-gel membrane and other related membrane technologies provides more feasible methods for preparing the optical fiber sensing membrane. Thirdly, the FOS has the characteristics of electromagnetic interference resistance, large transmission information quantity, small optical energy transmission loss, strong environment adaptability and the like; fourth, FOS can achieve self-referencing, requiring an additional reference electrode compared to electrochemical sensors. The FOS can obtain stable optical information by utilizing self-reference, and the instability of a sensing probe is avoided.
Molecular Imprinting Technique (MIT) refers to a process of preparing a Polymer having specific selectivity for a specific target molecule (template molecule), and the prepared Polymer is called a Molecular Imprinted Polymer (MIP). The molecularly imprinted polymer is an artificial antibody tailored as a target molecule, is known to have the characteristics of high selectivity, severe environment resistance and the like, is widely applied to various fields such as solid phase extraction, biomimetic sensors, enzyme simulation catalysis and the like, and has very wide application in environmental detection.
Molecularly imprinted fiber optic sensors (OFS-MIPs) apply MIPs as a sensitive material to fiber optic sensors. Generally, the MIPs are used as a sensing layer of an optical fiber sensor, light emitted by a light source is transmitted to the MIPs sensing layer through an optical fiber by the optical fiber sensor, the MIPs sensing layer interacts with an external measured substance, so that the optical characteristics of an optical signal are changed, a biochemical signal is converted into an optical signal, and the optical signal enters a signal demodulator through the optical fiber to perform qualitative/quantitative analysis on the measured substance. The coupling of the molecular imprinting and the optical fiber sensor at present specifically comprises: in-situ polymerization, adhesive surface coating, surface modification, capillary coupling and the like. The OFS-MIPs have the MIPs specificity recognition function, and meanwhile, the OFS-MIPs have the advantages of good stability, high sensitivity, simplicity in manufacturing, low cost, portability, low-consumption transmission, electromagnetic interference resistance, safety and the like of the optical fiber sensor, can realize real-time and remote monitoring by utilizing a modern communication technology, and have great development potential. Currently, the molecular imprinting optical fiber sensing technology is applied to a plurality of fields such as clinical analysis, food, environment and the like.
Disclosure of Invention
The invention provides a molecularly imprinted fluorescent optical fiber sensor, which is a detachable sensor, so that an optical fiber probe can be replaced, multi-target detection can be respectively carried out on the site, the sensor can be applied to on-site rapid detection of antibiotics in environmental water, the sensing film modified by the optical fiber probe can be easily damaged after the use, the optical fiber probe can be recovered, and unnecessary resource waste is reduced.
The second purpose of the invention is to provide a construction method of the molecularly imprinted fluorescent optical fiber sensor.
The third purpose of the invention is to provide a fluorescence detection method of the molecularly imprinted fluorescent optical fiber sensor.
The first purpose of the invention can be achieved by adopting the following technical scheme:
a molecular imprinting fluorescence optical fiber sensor comprises a laser light source, a Y-shaped optical fiber, a quartz optical fiber, a flange adapter and an optical fiber spectrometer, wherein the laser light source, the Y-shaped optical fiber and the optical fiber spectrometer are sequentially connected, the quartz optical fiber modifies a gel film containing molecular imprinting microspheres, and the Y-shaped optical fiber and the quartz optical fiber are detachably connected through the flange adapter;
the laser emitted by the laser source is transmitted to the gel film on the quartz optical fiber through the Y-shaped optical fiber, and the fluorescence signal of the gel film is reflected back to the Y-shaped optical fiber and transmitted to the optical fiber spectrometer through the Y-shaped optical fiber.
Furthermore, the optical fiber monitoring device further comprises a dark box, wherein one end of the Y-shaped optical fiber connected with the quartz optical fiber, the quartz optical fiber and the flange adapter are all arranged in the dark box.
Further, the device also comprises a computer, and the fiber spectrometer is connected with the computer.
The optical fiber spectrometer further comprises an optical filter, wherein the optical filter is arranged between the Y-shaped optical fiber and the optical fiber spectrometer, and the Y-shaped optical fiber is connected with the optical fiber spectrometer through the optical filter.
The second purpose of the invention can be achieved by adopting the following technical scheme:
a construction method of the molecularly imprinted fluorescent optical fiber sensor comprises the following steps:
synthesizing molecularly imprinted polymer nano-microspheres;
dispersing a part of synthesized molecularly imprinted polymer nano-microspheres in water to prepare molecularly imprinted microsphere aqueous dispersion;
transferring part of the prepared dispersion liquid into a small conical bottle, adding polyethylene glycol methyl diacrylate and 2-hydroxy-2-methyl propiophenone, magnetically stirring for a period of time, and degassing to obtain a semitransparent gel film pre-polymerization liquid;
inserting the quartz optical fiber into a hollow glass tube, injecting a part of gel film pre-polymerization liquid into the bottom end of the hollow glass tube, carrying out photopolymerization under an ultraviolet lamp for a period of time, and taking out the quartz optical fiber to obtain the quartz optical fiber for modifying the gel film containing the molecularly imprinted microspheres;
the laser light source, the Y-shaped optical fiber and the optical fiber spectrometer are sequentially connected, and the quartz optical fiber for modifying the gel film containing the molecular imprinting microsphere is connected with the Y-shaped optical fiber through the flange adapter.
Further, the synthetic molecularly imprinted polymer nanosphere specifically comprises:
filling template molecule powder into a round-bottom flask, adding acetonitrile solution to perform ultrasonic full dissolution, adding methacrylic acid, divinylbenzene and azobisisobutyronitrile, performing ultrasonic full dissolution, introducing nitrogen for a period of time, and sealing the round-bottom flask by using an adhesive tape;
putting the round-bottom flask into a constant-temperature water bath for reaction to obtain a white precipitation polymer, namely the molecularly imprinted polymer nano-microsphere;
centrifuging to remove the solvent in the round-bottom flask, washing to remove the unreacted organic solvent, and eluting the template molecules on the molecularly imprinted polymer nanospheres;
putting the molecular imprinting polymer nano-microspheres in a vacuum drying oven overnight to obtain the substitute molecular imprinting polymer.
Further, the washing step is to remove the unreacted organic solvent and elute the template molecule on the molecularly imprinted polymer nanosphere, and specifically includes:
repeatedly washing with a mixed solution of methanol and water to remove unreacted organic solvent;
eluting the template molecules on the molecularly imprinted polymer nano-microspheres on a shaking table by using a mixed elution solution of methanol and acetic acid until the template molecules of the supernatant of the eluent cannot be detected on an ultraviolet spectrophotometer, and washing away the acetic acid by using methanol.
Further, in the mixed solution of methanol and water, the ratio of methanol: water 1: 1.
further, in the elution solution of methanol and acetic acid, the ratio of methanol: ethanol ═ 8: 2.
further, the template molecule powder is filled into a round-bottom flask, specifically: 41mg to 42mg of template molecule powder is weighed and charged into a round bottom flask.
Further, the adding of methacrylic acid, divinylbenzene and azobisisobutyronitrile specifically comprises: adding 85-87 mul of methacrylic acid, 371-372 mul of divinylbenzene and 14-15 mg of azobisisobutyronitrile.
Further, the partially synthesized molecularly imprinted polymer nanospheres are specifically: weighing 2-3 mg of molecularly imprinted polymer nano-microspheres.
Further, the moving part is used for moving the prepared dispersion liquid into a small conical bottle, and specifically comprises the following steps: 2-4 ml of the prepared dispersion is transferred into a small conical bottle.
Further, the adding of the polyethylene glycol methyl diacrylate and the 2-hydroxy-2-methyl propiophenone specifically comprises the following steps: adding 1.6-20 ml of polyethylene glycol methyl diacrylate with average molecular weight of 700 and 22-24 mul of 2-hydroxy-2-methyl propiophenone.
Further, the insertion of the silica fiber into the hollow glass tube specifically comprises:
and sleeving the quartz optical fiber into a conical plastic mold, and inserting the conical plastic mold into the hollow glass tube to fix the quartz optical fiber in the center of the hollow glass tube.
Further, after injecting a part of gel film pre-polymerization liquid into the bottom end of the hollow glass tube, adjusting the distance between the quartz optical fiber and the bottom end of the hollow glass tube to be 0.2-0.3 cm.
Further, injecting a part of gel film pre-polymerization liquid into the bottom end of the hollow glass tube specifically comprises: and injecting 18-22 mul of the gel film pre-polymerization solution prepared in the second step into the bottom end 10 of the hollow glass tube.
The third purpose of the invention can be achieved by adopting the following technical scheme:
a fluorescence detection method based on the molecularly imprinted fluorescent optical fiber sensor comprises the following steps:
absorbing the detection solution into a centrifugal tube, putting the quartz optical fiber into the centrifugal tube for soaking, and performing ultrasonic absorption for a period of time;
after adsorption is finished, taking out the quartz optical fiber, soaking the quartz optical fiber in deionized water, and washing away unadsorbed residual adsorption liquid;
the processed quartz optical fiber is connected into the whole instrument through the flange adapter, laser emitted by the laser source is transmitted to the gel film on the quartz optical fiber through the Y-shaped optical fiber, a fluorescence signal of the gel film is reflected back to the Y-shaped optical fiber and is transmitted to the optical fiber spectrometer through the Y-shaped optical fiber, and therefore fluorescence detection is achieved.
Further, absorb detection solution in the centrifuging tube, specifically be: sucking 0.8 ml-1.2 ml of detection solution into a centrifuge tube.
Compared with the prior art, the invention has the following beneficial effects:
1. the sensor combines the molecular imprinting technology with the optical fiber sensing technology, not only has the advantages of high selectivity of the molecular imprinting polymer, miniaturization of the optical fiber sensing technology and the like, but also has the advantages of lightness, rapidness, simple and convenient operation, low cost and the like compared with a large-scale optical sensor; different from the existing optical fiber sensor, the molecular imprinting material coated in the design can be quickly washed away by changing the conditions after the detection is finished, namely, the modified optical fiber probe can be recycled, so that the material cost is low; the instrument has the advantages of being detachable and replaceable while keeping the light transmission efficiency, can realize rapid on-site monitoring of multiple targets, has certain research significance for on-site rapid detection of antibiotics in the environmental water body, can be applied to on-site rapid monitoring of the antibiotics in the environmental water body, and solves the problems that the existing antibiotic on-site monitoring method is poor in stability and reproducibility, high in analysis cost and difficult to provide real-time pollution data of the antibiotics in the environmental water body.
2. The sensor can be provided with the optical filter between the Y-shaped optical fiber and the optical fiber spectrometer, the Y-shaped optical fiber is connected with the optical fiber spectrometer through the optical filter, and the exciting light which is reflected excessively can be filtered through the optical filter so as to reduce the detection error.
3. In the modification process of the optical fiber probe, polyethylene glycol methyl diacrylate is added when gel film pre-polymerization liquid is prepared, the polyethylene glycol methyl diacrylate can initiate free radical polymerization by a photoinitiator under illumination to form a net structure, and the molecularly imprinted microspheres are wrapped in the gel film to keep the fluorescence efficiency.
4. In the modification process of the optical fiber probe, the quartz optical fiber is sleeved into the conical plastic mold, and the conical plastic mold is inserted into the hollow glass tube, so that the quartz optical fiber is fixed at the center of the hollow glass tube, and the detection error is reduced; and after injecting gel film pre-polymerization liquid, adjusting the distance between the quartz optical fiber and the bottom end of the hollow glass tube to be 0.2-0.3 cm so as to reduce the detection error among different components.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a structural diagram of a molecularly imprinted fluorescent optical fiber sensor according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of a gel film modified by a fiber-optic probe according to an embodiment of the present invention.
FIG. 3 is a schematic diagram of a silica optical fiber for synthesizing a modified gel film according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating the effect of testing errors before and after adsorption.
FIG. 5 is a graph showing the enhancement of the fluorescence effect of adsorption test according to the embodiment of the present invention.
FIG. 6 is a time chart of the optimized adsorption effect according to the embodiment of the present invention.
FIG. 7 is a graph showing the effect of selectivity on adsorbed species in accordance with an embodiment of the present invention.
The system comprises a laser light source 1, a 2-Y-shaped optical fiber, a 3-quartz optical fiber, a 4-flange adapter, a 5-optical fiber spectrometer, a 6-dark box, a 7-computer, an 8-optical filter, a 9-conical plastic mold, a 10-hollow glass tube and an 11-ultraviolet lamp.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer and more complete, the technical solutions in the embodiments of the present invention will be described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments, and all other embodiments obtained by a person of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.
Example (b):
as shown in fig. 1, the embodiment provides a molecular imprinting fluorescence optical fiber sensor, which includes a laser light source 1, a Y-shaped optical fiber 2, a silica optical fiber 3, a flange adapter 4, and an optical fiber spectrometer 5, where the laser light source 1, the Y-shaped optical fiber 2, and the optical fiber spectrometer 5 are sequentially connected, the silica optical fiber 3 is an optical fiber probe, and modifies a gel film containing molecular imprinting microspheres, that is, the gel film is a sensing film, and the Y-shaped optical fiber 2 and the silica optical fiber 3 are detachably connected through the flange adapter 4, that is, the silica optical fiber 3 is replaceable, which is beneficial to monitoring multiple targets.
Further, in order to improve the monitoring effect, the molecularly imprinted fluorescent fiber sensor of the present embodiment further includes a dark box 6, and the end of the Y-shaped fiber 3 connected to the silica fiber 3, the silica fiber 3 and the flange adapter 4 are all disposed in the dark box 6.
Further, the molecularly imprinted fluorescent fiber sensor of the present embodiment further includes a computer 7, the fiber spectrometer 5 is connected to the computer 7, and the computer 7 collects and analyzes signals received by the fiber spectrometer 5.
Further, the molecularly imprinted fluorescent fiber sensor of the embodiment further includes a filter 8, the filter 8 is disposed between the Y-shaped fiber 2 and the fiber spectrometer 5, the Y-shaped fiber 2 is connected to the fiber spectrometer 5 through the filter 8, and the filter 3 is used for filtering the excitation light of the unwanted reflection to reduce the detection error.
Specifically, the laser light source 1 of the present embodiment employs a fixed wavelength laser, the power of which is 100W, and the excitation wavelength is 405 nm; the inner diameter of the Y-shaped optical fiber 2 is 600 μm, one end of the two branched ends is connected with the laser light source 1, the other end is connected with the optical filter 8, the other end which is not branched is connected with the flange adapter 4 and is arranged in the dark box 6; the wavelength of the optical filter 8 is 420nm, and the optical filter is connected with the optical fiber spectrometer 5 through a single 600nm optical fiber; the optical fiber spectrometer 5 adopts the optical fiber spectrometer of maya2000pro of blue optical company, and all optical fiber connection interfaces are SMA905 interfaces, and after the optical fiber spectrometer 5 is connected with the computer 7, the main parameters are set as follows: the integration time is 20, the average times is 10, the average width is 4, the detection band is 415-650, the interval is 0, and the wavelength correction is 0; the silica optical fiber 3, having an inner diameter of 1000 μm and a length of 5cm, was attached to the flange adapter 4 and placed in the dark box 6.
The monitoring principle of the molecularly imprinted fluorescent optical fiber sensor of the embodiment is as follows: the laser source 1 emits laser with fixed wavelength, the laser reaches the quartz optical fiber 3 in the dark box through the Y-shaped optical fiber 2, namely the laser is transmitted to a gel film on the quartz optical fiber 3, a fluorescence signal of a sensing film on the quartz optical fiber 3 is reflected back to the Y-shaped optical fiber 2, then the fluorescence signal is transmitted to the optical fiber spectrometer 5 through the filter 8, and finally signal acquisition and analysis are carried out on the computer 7.
The embodiment also provides a method for constructing the molecularly imprinted fluorescent optical fiber sensor, which comprises the following steps:
(1) synthesis of molecularly imprinted polymer nanospheres
a. Weighing 41.4mg of ciprofloxacin by taking the ciprofloxacin as a template molecule, putting ciprofloxacin powder into a round-bottom flask, adding acetonitrile solution to perform ultrasonic full dissolution, adding 86 mu l of methacrylic acid (functional monomer), 371.5 mu l of divinylbenzene and azobisisobutyronitrile (cross-linking agent), performing ultrasonic 10 minutes to completely dissolve, introducing nitrogen for 10 minutes, and sealing the round-bottom flask by using an adhesive tape.
b. And (3) placing the round-bottom flask into a constant-temperature water bath kettle at 60 ℃ for reaction for 24 hours to obtain a white precipitation polymer, namely the molecularly imprinted polymer nano-microsphere with the diameter of about 200 nm.
c. After removal of the solvent by centrifugation, the mixture was washed with methanol: the mixed solution of water 1:1(V/V) was repeatedly washed to remove the unreacted organic solvent, and then methanol: eluting the template molecules by using a mixed elution solution of acetic acid (8: 2) (V/V) on a shaking table until the template molecules of the supernatant of the eluent cannot be detected on an ultraviolet spectrophotometer to prove that the template molecules are completely eluted, finally washing off the acetic acid by using methanol, and putting the mixture in a vacuum drying oven at 60 ℃ overnight to obtain the substituted molecularly imprinted polymer.
The particle size of the synthesized molecularly imprinted polymer microspheres is about 200nm and is uniformly dispersed, a small amount of ciprofloxacin molecules are embedded in the molecularly imprinted polymer microspheres after the template molecules are eluted, weak fluorescence signals are contained in the molecularly imprinted polymer microspheres, and the template molecules and the molecularly imprinted polymer microspheres are acted by hydrogen bonds, so that the hydrogen bonds of the molecularly imprinted polymer microspheres are destroyed by using a mixed elution solution of methanol and acetic acid, and the template molecules are completely eluted.
(2) Prepared gel film pre-polymerization liquid
a. Weighing 2.5mg of dried molecularly imprinted polymer microspheres, and dispersing in 10ml of water to prepare a molecularly imprinted microsphere water dispersion.
b. Transferring 3ml of the prepared dispersion liquid into a 10ml small conical flask, adding 1.8ml of polyethylene glycol methyl diacrylate with the average molecular weight of 700 and 23 mul of 2-hydroxy-2-methyl propiophenone (photoinitiator), magnetically stirring for 5min, and degassing to obtain the semitransparent gel film pre-polymerization liquid.
The polyethylene glycol methyl diacrylate can be subjected to free radical polymerization initiated by a photoinitiator under the irradiation of light to form a net structure, and the molecularly imprinted polymer microspheres are wrapped in the gel film to keep the fluorescence efficiency.
(3) Modified optical fiber probe
The modification of the fiber optic probe is performed according to fig. 2, which specifically includes:
a. the quartz optical fiber 3 is sleeved in a conical plastic mold 9, and the conical plastic mold 9 is inserted into a hollow glass tube 10 with the inner diameter of 2mm and the length of 2cm, so that the distance between one end of the quartz optical fiber 3 inserted into the hollow glass tube 10 and the bottom end of the hollow glass tube 10 is 0.25 cm.
b. And (3) injecting 20 mul of the gel film pre-polymerization liquid prepared in the step (2) into the bottom end of the hollow glass tube, performing photopolymerization for 10 minutes under an ultraviolet lamp 11, and taking out the silica optical fiber to obtain the silica optical fiber with the gel film modified with the molecularly imprinted microspheres, as shown in figure 3.
Wherein, the conical plastic grinding tool 10 is used for fixing the quartz optical fiber 8 at the center of the hollow glass tube 11 so as to reduce the detection error; after 20 mul of gel film pre-polymerization liquid is injected, the distance between the quartz optical fiber and the bottom end of the hollow glass tube 10 is adjusted to be 0.25cm, so that the detection errors among different components are reduced, and the molecularly imprinted polymer microspheres in the gel film are uniformly dispersed and regularly arranged.
(4) Instrument for constructing sensor
A laser light source 1, a Y-shaped optical fiber 2, an optical filter 8, an optical fiber spectrometer 5 and a computer 7 are sequentially connected, a quartz optical fiber 3 for modifying a gel film containing molecular imprinting microspheres is connected with the Y-shaped optical fiber 2 through a flange adapter 4, and one end of the Y-shaped optical fiber 3 connected with the quartz optical fiber 3, the quartz optical fiber 3 and the flange adapter 4 are placed in a dark box 6.
The embodiment also provides a fluorescence detection method based on the molecularly imprinted fluorescent optical fiber sensor, which comprises the following steps:
(1) and (3) ultrasonically treating the modified small section of the quartz optical fiber 3 with deionized water for three times, wherein each time is 10min, in order to wash out unreacted impurities and enable the unreacted impurities to reach the swelling balance of a gel film.
(2) Taking the ciprofloxacin solution as a detection solution, sucking 1ml of ciprofloxacin solution into a 10ml centrifugal tube, putting the quartz optical fiber 3 into the centrifugal tube, soaking, and performing ultrasonic absorption for 30 min.
(3) And after adsorption is finished, taking out the quartz optical fiber 3, and soaking the quartz optical fiber 3 in deionized water for 10min to remove the interference of nonspecific adsorption of antibiotics on the gel film.
(4) The processed quartz optical fiber 3 is connected into the whole instrument through a flange adapter 4, the laser light source 1 emits laser with fixed wavelength, the laser reaches the quartz optical fiber 3 in a dark box through the Y-shaped optical fiber 2, namely the laser is transmitted to a gel film on the quartz optical fiber 3, a fluorescence signal of a sensing film on the quartz optical fiber 3 is reflected back to the Y-shaped optical fiber 2 and then transmitted to the optical fiber spectrometer 5 through the filter 8 to realize fluorescence detection, and finally, signal acquisition and analysis are carried out on a computer 7.
The detection effect of the embodiment is as follows:
A. FIG. 4 is a graph showing the comparison between the initial wavelength of 10 modified optical fibers tested in parallel and the fluorescence intensity of 1ml of ciprofloxacin solution adsorbed by 5X 10-4mol/l under the condition of ultrasound for 20min before and after adsorption (note: ciprofloxacin has the optimal emission wavelength of 468nm at 405nm so that the collected data is the fluorescence intensity of 468 nm), it can be seen that the fluorescence intensity after adsorption is enhanced, and the error of the parallel sample is within the acceptable range; FIG. 5 is a comparison between before and after peak enhancement, and it can be seen that the optimal emission peak is 468nm, and the peak pattern before and after adsorption is unchanged, and the emission peak has no obvious red shift and blue shift.
B. Fig. 6 is a graph of the effect of testing adsorption time. And testing the adsorption ultrasonic time to judge the optimal adsorption time and judge whether the adsorption ultrasonic time meets the condition of rapid monitoring. Experiments show that the fluorescence enhancement reaches the maximum value within 30min, so the optimal adsorption time can be completely adsorbed within 30min, and the conditions of rapid on-site monitoring within 30min are met.
C. Fig. 7 shows the selectivity of the sensor of the present example tested. And selecting antibiotics with different similar structures with the ciprofloxacin to adsorb, and judging the selectivity of the adsorbed sensor at the wavelength of 468 nm. As can be seen from FIG. 7, the sensor has good selectivity for ciprofloxacin, the fluorescence enhancement rate (calculated by F/F0-1, F is the fluorescence intensity at the position of 468nm of wavelength after adsorption, and F0 is the fluorescence intensity at the position of 468nm of wavelength before adsorption) reaches more than twice of that of antibiotics with similar structures, and the sensor meets the condition of specific identification and detection.
In conclusion, the sensor combines the molecular imprinting technology with the optical fiber sensing technology, not only has the advantages of high selectivity of the molecular imprinting polymer, miniaturization of the optical fiber sensing technology and the like, but also has the advantages of lightness, rapidness, simplicity and convenience in operation, low cost and the like compared with a large-scale optical sensor; different from the existing optical fiber sensor, the molecular imprinting material coated in the design can be quickly washed away by changing the conditions after the detection is finished, namely, the modified optical fiber probe can be recycled, so that the material cost is low; the instrument has the advantages of being detachable and replaceable while keeping the light transmission efficiency, can realize rapid on-site monitoring of multiple targets, has certain research significance for on-site rapid detection of antibiotics in the environmental water body, can be applied to on-site rapid monitoring of the antibiotics in the environmental water body, and solves the problems that the existing antibiotic on-site monitoring method is poor in stability and reproducibility, high in analysis cost and difficult to provide real-time pollution data of the antibiotics in the environmental water body.
The above description is only for the preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can substitute or change the technical solution and the inventive concept of the present invention within the scope of the present invention.
Claims (7)
1. A method for constructing a molecularly imprinted fluorescent optical fiber sensor, wherein the molecularly imprinted fluorescent optical fiber sensor comprises a laser light source, a Y-shaped optical fiber, a quartz optical fiber, a flange adapter and an optical fiber spectrometer, and the method comprises the following steps:
synthesizing molecularly imprinted polymer nano-microspheres;
dispersing a part of synthesized molecularly imprinted polymer nano-microspheres in water to prepare molecularly imprinted microsphere aqueous dispersion;
transferring part of the prepared dispersion liquid into a small conical bottle, adding polyethylene glycol methyl diacrylate and 2-hydroxy-2-methyl propiophenone, magnetically stirring for a period of time, and degassing to obtain a semitransparent gel film pre-polymerization liquid;
inserting the quartz optical fiber into a hollow glass tube, injecting a part of gel film pre-polymerization liquid into the bottom end of the hollow glass tube, carrying out photopolymerization under an ultraviolet lamp for a period of time, and taking out the quartz optical fiber to obtain the quartz optical fiber for modifying the gel film containing the molecularly imprinted microspheres;
connecting a laser source, a Y-shaped optical fiber and an optical fiber spectrometer in sequence, connecting a quartz optical fiber for modifying a gel film containing molecular imprinting microspheres with the Y-shaped optical fiber through a flange adapter, transmitting laser emitted by the laser source to the gel film on the quartz optical fiber through the Y-shaped optical fiber, reflecting a fluorescence signal of the gel film back to the Y-shaped optical fiber, and transmitting the fluorescence signal to the optical fiber spectrometer through the Y-shaped optical fiber;
the synthesized molecularly imprinted polymer nanosphere specifically comprises:
filling template molecule powder into a round-bottom flask, adding acetonitrile solution to perform ultrasonic full dissolution, adding methacrylic acid, divinylbenzene and azobisisobutyronitrile, performing ultrasonic full dissolution, introducing nitrogen for a period of time, and sealing the round-bottom flask by using an adhesive tape;
putting the round-bottom flask into a constant-temperature water bath for reaction to obtain a white precipitation polymer, namely the molecularly imprinted polymer nano-microsphere;
centrifuging to remove the solvent in the round-bottom flask, washing to remove the unreacted organic solvent, and eluting the template molecules on the molecularly imprinted polymer nanospheres;
putting the molecular imprinting polymer nano-microspheres in a vacuum drying oven overnight to obtain a substitute molecular imprinting polymer;
the washing step is to remove the unreacted organic solvent and elute the template molecules on the molecularly imprinted polymer nanospheres, and specifically comprises the following steps:
repeatedly washing with a mixed solution of methanol and water to remove unreacted organic solvent;
eluting the template molecules on the molecularly imprinted polymer nano-microspheres on a shaking table by using a mixed elution solution of methanol and acetic acid until the template molecules of the supernatant of the eluent cannot be detected on an ultraviolet spectrophotometer, and washing away the acetic acid by using methanol.
2. The building method according to claim 1, wherein the silica optical fiber is inserted into a hollow glass tube, in particular:
and sleeving the quartz optical fiber into a conical plastic mold, and inserting the conical plastic mold into the hollow glass tube to fix the quartz optical fiber in the center of the hollow glass tube.
3. The construction method according to claim 1, wherein after injecting a part of the gel film pre-polymerization liquid into the bottom end of the hollow glass tube, the distance between the quartz optical fiber and the bottom end of the hollow glass tube is adjusted to be 0.2 cm-0.3 cm.
4. The construction method according to claim 1, wherein the molecularly imprinted fluorescent fiber sensor further comprises a dark box, and the end of the connection of the Y-shaped optical fiber and the quartz optical fiber, the quartz optical fiber and the flange adapter are all arranged in the dark box.
5. The construction method according to claim 1, wherein the molecularly imprinted fluorescent fiber sensor further comprises a computer, and the fiber spectrometer is connected with the computer.
6. The construction method according to claim 1, wherein the molecularly imprinted fluorescent fiber sensor further comprises a filter, the filter is arranged between the Y-shaped fiber and a fiber spectrometer, and the Y-shaped fiber is connected with the fiber spectrometer through the filter.
7. The construction method according to claim 1, wherein the fluorescence detection process of the molecularly imprinted fluorescent optical fiber sensor is as follows:
absorbing the detection solution into a centrifugal tube, putting the quartz optical fiber into the centrifugal tube for soaking, and performing ultrasonic absorption for a period of time;
after adsorption is finished, taking out the quartz optical fiber, soaking the quartz optical fiber in deionized water, and washing away unadsorbed residual adsorption liquid;
the processed quartz optical fiber is connected into the whole instrument through the flange adapter, laser emitted by the laser source is transmitted to the gel film on the quartz optical fiber through the Y-shaped optical fiber, a fluorescence signal of the gel film is reflected back to the Y-shaped optical fiber and is transmitted to the optical fiber spectrometer through the Y-shaped optical fiber, and therefore fluorescence detection is achieved.
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