CN105203509B - " crocodile skin shape " fluorescent nano-fiber is to picric detection method - Google Patents

Abstract

The invention discloses a method for detecting picric acid by "crocodile skin-like" fluorescent nanofibers, comprising step 1: preparing a P(VDF-HFP) solution and a chloroform solution of TPE-2pTPA, and then mixing the two to prepare TPE-2pTPA/P (VDF-HFP) solution; step 2: place the TPE-2pTPA/P(VDF-HFP) solution in a low temperature environment in the refrigerator for seven days; step 3: place the treated TPE-2pTPA/P(VDF-HFP) solution Carry out electrospinning, prepare the TPE-2pTPA/P(VDF-HFP) nanofiber film with " alligator skin shape "; Different concentrations of PA solutions were gradually added dropwise to test. The invention has the advantages of simple operation, low cost, high sensitivity, fast response speed, safety, non-toxicity, no pollution to the environment, economical applicability and the like.

Description

"Alligator skin-like" fluorescent nanofibers for the detection of picric acid

technical field

The invention relates to the field of explosive detection technology and electrospinning technology, in particular to a method for detecting picric acid by "crocodile skin-like" fluorescent nanofibers.

Background technique

2,4,6-Trinitrophenol (commonly known as picric acid, PA) is an important organic chemical raw material, which is widely used in the production of leather, pharmaceuticals, yellow dyes and preservatives (Niu Q, Gao K , Lin Z, et al.Amine-capped carbon dots as a nanosensor for sensitive and selective detection of picric acid in aqueous solution via electrostatic interaction[J].AnalyticalMethods,2013,5(21):6228-6233.). But at the same time, picric acid is also a common explosive and a typical pollutant, which has prominent public safety threats and ecological damage, and is also a potential carcinogen (Kumar S, Venkatramaiah N, Patil S. Fluoranthene Based Derivatives for Detection of TraceExplosive Nitroaromatics[J].Journal of Physical Chemistry C,2013,117(14):7236-7245.). Therefore, it is very important to study the detection method of trace picric acid for the prevention of terrorist crimes and environmental pollution monitoring.

Among the current explosive detection methods, fluorescent chemical sensors have attracted extensive attention due to their high sensitivity and ease of detection. However, developing an efficient fluorescent chemical sensor for the detection of explosives such as PA, 2,4-dinitrotoluene (DNT), and 2,4,6-trinitrotoluene (TNT) remains a challenge. In recent years, there are relatively few reports on the use of one-dimensional nanofibers as sensors for the detection of explosives. Therefore, exploiting the unique properties of fibers to develop novel materials is of great significance in the scientific and industrial circles. (Sun X, Liu Y, Shaw G, et al.Fundamental Study of Electrospun Pyrene-Polyethersulfone Nanofibers Using Mixed Solvents for Sensitive and Selective Explosives Detection in Aqueous Solution[J].ACS Applied Materials&Interfaces,2015,7(24):13189-13197.)

It is a very simple and effective method to prepare nanofiber materials with diameters ranging from tens of nanometers to microns by electrospinning (Xing C, Guan J, Li Y, et al. Effect of a Room-Temperature Ionic Liquid on the Structure and Properties of Electrospun Poly(vinylidenefluoride) Nanofibers[J].ACS Applied Materials&Interfaces,2014,6(6):4447-4457.). Electrospinning continuously produces a large number of nanofibers by applying a high voltage to a viscous solution (Park SM, Kim D S. Electrolyte-Assisted Electrospinning for a Self-Assembled, Free-Standing Nanofiber Membrane on a Curved Surface[J]. Advanced Materials, 2015, 27(10):1682-+). The resulting nanofibers have been widely used in tissue engineering due to their controllable morphology, large specific surface area (approximately 1 to 100 m ² .g ^-1 ), and porous structure (Trinca RB, Abraham GA, Felisberti MI. Electrospun nanofibrous scaffolds of segmented polyurethanes based on PEG, PLLA and PTMC blocks: Physico-chemical properties and morphology[J].Materialsscience&engineering.C,Materials for biological applications,2015,56:511-7.), filtration (Liu B, Zhang S,Wang X,et al.Efficient and reusable polyamide-56nanofiber/nets membrane with bimodal structures for air filtration[J].Journal of colloid and interface science,2015,457:203-11), electronic devices (Zhu H,Du M , ZhangM, et al.The design and construction of 3D rose-petal-shaped MoS2 hierarchical nanostructures with structure-sensitive properties[J].Journal of Materials Chemistry A,2014,2(21):7680-7685.), catalyst support (Ghouri ZK,Barakat NAM,ObaidM,et al.Co/CeO ₂ -decorated carbon nanofibers as effective non-precious electro-catalyst for fuel cells application in alkaline medium[J].CeramicsInternational,2015,41(2):2271-2278.) , Reinforced composite materials (Tian M, Wang YN, WangR.Synthesis and characterization of novel high-performance thin filmnanocomposite(TFN)FO membranes with nanofibrous substrate reinforced byfunctionalized carbon nanotubes[J].Desalination,2015,370:79-86.) and sensor devices (Wang L,Deng J,Lou Z,et al.Cross -linked p-type Co3O4 octahedral nanoparticlesin 1D n-type TiO2 nanofibers for high-performance sensing devices[J].Journal of Materials Chemistry A,2014,2(26):10022-10028.), etc. Due to the high sensitivity and fast response of fluorescence sensors, electrospun nanofibrous materials have been developed as promising nanomaterials in fluorescence sensing. Currently, several chemical sensors based on electrospun fiber membranes have been reported for the detection of some analytes in aqueous phase, mainly including metal ions (Min M, Wang X, Chen Y, et al. Highly sensitive and selective Cu2+sensorbased on electrospun rhodamine dye doped poly(ether sulfones) nanofibers[J].Sensors and Actuators B-Chemical,2013,188:365-371.), nitrite (Ding Y,Wang Y,Li B,et al.Electrospun hemoglobin microbelts based biosensor for sensitive detection of hydrogen peroxide and nitrite[J].Biosensors&Bioelectronics,2010,25(9):2009-2015.), volatile gases (Liang X,Kim TH,Yoon JW,et al.Ultrasensitiveand ultraselective detection of H2S using electrospun CuO-loaded In2O3nanofiber sensors assisted by pulse heating [J]. Sensors and Actuators B-Chemical, 2015, 209: 934-942.), etc. However, these films are generally prepared by covering, dye doping, or other physical methods, and these preparation methods have various problems, such as fluorescence quenching due to aggregation of fluorophores, fluorescence leakage, and internal layer analysis. (Long Y, Chen H, Yang Y, et al. Electrospunnanofibrous film doped with a conjugated polymer for DNT fluorescence sensor [J]. Macromolecules, 2009, 42 (17): 6501-6509.). A more direct and simple method is to modify the surface of polymer nanofibers, which will not affect the bulk properties of the nanofibers. The method of surface modification depends to a large extent on the properties of the polymer that forms the fiber. So far, the surface modification method mainly includes plasma treatment (Padil VT, Nguyen NHA, Rozek Z, et al.Synthesis, fabrication and antibacterial properties of a plasma modified electrospun membrane consisting of gum Kondagogu, dodecenyl succinic anhydride and poly(vinyl alcohol)[J].Surface&Coatings Technology,2015,271:32-38.), physical adsorption method (Polini A, Pagliara S, Stabile R, et al .Collagen-functionalised electrospun polymer fibers for bioengineering applications[J].Soft Matter,2010,6(8):1668-1674.), self-assembly method (Duan G, Jiang S, Jerome V, et al. Ultralight, Soft Polymer Sponges by Self-Assembly of Short Electrospun Fibers in Colloidal Dispersions[J].Advanced Functional Materials,2015,25(19):2850-2856.) and covalent grafting method (Mangeon C,Mahouche-Chergui S,Versace DL,et al. Poly(3-hydroxyalkanoate)-grafted carbonnanotube nanofillers as reinforcing agent for PHAs-based electrospun mats[J].Reactive&Functional Polymers,2015,89:18-23.), etc.

The present invention makes full use of the simplicity of electrospinning technology and the simple doping of a small molecule fluorescent probe (TPE-2pTPA, structure shown in Figure 1) with aggregation-induced emission effect (aggregation-induced emission, AIE), and develops a A portable "alligator-skin-like" nanofibrous membrane sensor, and a novel surface modification method that is simpler and more convenient. This fiber surface modification method uses the difference in volatility of the solvent in the P(VDF-HFP) (poly(vinylidene fluoride-co-hexafluoropropylene)) solution and the TPE-2pTPA solution to connect organic fluorescent molecules to the nanoparticles in the form of "particles". The surface of the fiber (as shown in Figure 2), thereby forming a kind of "crocodile skin-like" nanofiber, so that these "particles" organic fluorescent molecules can reasonably enter the detection system through the nanofiber, and the surface properties change minimally. Furthermore, this approach avoids the problems mentioned above. This "alligator-skin-like" fluorescent nanofiber sensor exhibits high fluorescence sensitivity and very short response time for the detection of picric acid (PA) in aqueous solution, which has never been reported in the literature. This surface modification technology has great potential practical value for the development of high-performance sensing materials for the detection of explosives in aqueous solutions.

Contents of the invention

In order to solve the above-mentioned technical problems, the present invention provides a highly sensitive detection method for explosives in the water phase by "crocodile-skin-like" tetraarylethene fluorescent nanofibers. The technical scheme adopted is as follows:

The detection method of "crocodile skin-like" fluorescent nanofibers to picric acid, the steps are as follows:

Step 1: preparing a P(VDF-HFP) solution and a chloroform solution of TPE-2pTPA, and then mixing the two to prepare a TPE-2pTPA/P(VDF-HFP) solution;

Step 2: Place the TPE-2pTPA/P(VDF-HFP) solution in a low temperature environment in the refrigerator for seven days;

Step 3: Electrospinning the treated TPE-2pTPA/P(VDF-HFP) solution to prepare a TPE-2pTPA/P(VDF-HFP) nanofiber membrane with "crocodile skin shape";

Step 4: Gradually add different concentrations of PA solutions to the "crocodile-skin-like" TPE-2pTPA/P(VDF-HFP) nanofiber membrane for detection.

The method for preparing P(VDF-HFP) solution in step 1 is as follows:

Mix acetone and N,N-dimethylacetamide at a ratio of 7:3 by volume to obtain a mixed solvent, then mix P(VDF-HFP) with the mixed solvent at a mass ratio of 13:87, and at 50°C Stir and dissolve for 12h (hours) to obtain a P(VDF-HFP) solution.

The method for preparing TPE-2pTPA chloroform solution in step 1 is as follows:

Dissolve 0.2 g of TPE-2pTPA in 1 mL of chloroform solution to obtain a nearly saturated solution of TPE-2pTPAl.

In step 1, the mass fraction of TPE-2pTPA/P(VDF-HFP) solution is 5%, that is, the mass ratio of TPE-2pTPA to P(VDF-HFP) is 5:95.

Step 2 During the electrospinning process, the voltage is 15kV, the advancing speed of the syringe is 0.002mm/s, and the receiving device is a 29.2cm×29.2cm stainless steel receiving plate with a 2.5cm×7.5cm glass slide attached to it.

The invention has the advantages of simple operation, low cost, high sensitivity, fast response speed, safety, non-toxicity, no pollution to the environment, economical applicability and the like.

Description of drawings

Figure 1 Structure of TPE-2pTPA.

Fig. 2 SEM image of "crocodile skin-like" TPE-2pTPA/P(VDF-HFP) nanofiber membrane.

Fig. 3 Fluorescence emission spectra of "crocodile skin-like" tetraarylethene nanofiber membranes under different concentrations of PA solutions.

Fig. 4 Quenching efficiency of "alligator-skin-like" TPE-2pTPA/P(VDF-HFP) nanofibrous membrane under different concentrations of PA solutions.

Detailed ways:

The present invention uses a simple doping method to dope a TPE derivative (TPE-2pTPA, structure shown in Figure 1) with an aggregation-induced emission effect (aggregation-induced emission, AIE) into P(VDF -HFP) (poly(vinylidene fluoride-co-hexafluoropropylene)), using the characteristics of different solvent volatility in the two solutions, the TPE-2pTPA/P(VDF-HFP) solution was made into a new type of "crocodile" by electrospinning technology. "Skin-like" fluorescent nanofibrous membrane sensor, thus proposing a simpler and more convenient novel surface modification method. The sensor connects organic fluorescent molecules to the surface of nanofibers in the form of "particles", thereby forming a "crocodile skin-like" nanofiber, so that these "particles" organic fluorescent molecules can reasonably enter the detection system through the nanofibers, and Minimal change in surface properties. In addition, this method can effectively avoid various problems existing in traditional preparation methods, such as fluorescence self-quenching due to aggregation of fluorophores, fluorescence leakage, and diffusion of analytes in the inner layer. This surface modification technology has great potential practical value for the development of high-performance sensing materials for the detection of explosives in aqueous solutions.

The morphology of the obtained "alligator skin-like" fluorescent nanofibrous membrane was observed with a scanning electron microscope (SEM) (as shown in FIG. 2 ). The optical properties of the fiber film were characterized by a fluorescence spectrometer, and the sensing performance of the fluorescent nanofiber film sensor for PA was studied. Figure 3 shows the fluorescence emission spectrum of the fluorescent nanofiber film with the concentration of quencher PA molecules. It can be seen that as the concentration of PA increases, the fluorescence intensity of the nanofiber film gradually decreases, and the detection limit of PA is 1.0×10 ^-8 g/mL, and the quenching efficiency is as high as 48.60% at this time (as shown in Figure 4 shown).

The specific implementation is further set forth below:

Step 1: preparing a P(VDF-HFP) solution and a chloroform solution of TPE-2pTPA, and then mixing the two to prepare a TPE-2pTPA/P(VDF-HFP) solution;

Acetone (Acetone, Act) and N, N-dimethylacetamide (Dimethylacetamide, DMAC) are mixed in the ratio of 7:3 by volume, obtain mixed solvent, then P (VDF-HFP) and mixed solvent are mixed with 13: Mix at a mass ratio of 87, stir and dissolve at 50°C for 12 hours (hours) to obtain a P(VDF-HFP) solution;

Dissolve 0.2g of TPE-2pTPA in 1mL of chloroform solution to obtain a nearly saturated solution of TPE-2pTPA;

Prepare the TPE-2pTPA/P (VDF-HFP) solution with a series of different mass fractions such as 5%, 10%, 15% and 20% by the two solutions according to different mass ratios, and prepare TPE-2pTPA/P (VDF-HFP) with a mass fraction of 5%. In P(VDF-HFP) solution, the mass ratio of TPE-2pTPA to P(VDF-HFP) is 5:95, and when TPE-2pTPA/P(VDF-HFP) solution with a mass fraction of 10% is prepared, TPE-2pTPA and P (VDF-HFP) mass ratio is 1:9, and so on. The present invention selects a TPE-2pTPA/P(VDF-HFP) solution with a mass fraction of 5%, wherein the mass ratio of TPE-2pTPA to P(VDF-HFP) is 5:95.

Step 2: Place the TPE-2pTPA/P(VDF-HFP) solution in a refrigerator at a low temperature for seven days.

The prepared TPE-2pTPA/P(VDF-HFP) solution was transferred to a small brown glass bottle and tightly capped, and placed in a refrigerator for seven days.

Step 3: Electrospinning the treated TPE-2pTPA/P(VDF-HFP) solution to prepare a TPE-2pTPA/P(VDF-HFP) nanofiber membrane with "crocodile skin shape";

A series of treated TPE-2pTPA/P(VDF-HFP) solutions with different mass fractions were electrospun to prepare fluorescent nanofiber membranes with a "crocodile skin-like" appearance. The voltage during the spinning process was 15kV, and the syringe The advancing speed is 0.002mm/s, the receiving device is a 29.2cm×29.2cm stainless steel receiving plate and a 2.5cm×7.5cm glass slide is attached on it; Observe the morphology of the film (as shown in Figure 2), and use a fluorescence spectrometer to characterize the optical properties of the film, that is, use a fluorescence spectrometer to test whether the nanofiber film has fluorescence characteristics and the size of its fluorescence intensity. In the subsequent PA detection, the fluorescence intensity of the fiber membrane was tested with a fluorescence spectrometer after adding PA, and it was observed that the fluorescence intensity of the fiber membrane decreased significantly after adding PA.

Step 4: Gradually add different concentrations of PA solutions to the "crocodile-skin-like" TPE-2pTPA/P(VDF-HFP) nanofiber membrane for detection.

The PA solutions with concentrations of 10 ^-8 , 10 ^-7 , 10 ^-6 , 10 ^-5 and 10 ^-4 g/mL were sequentially added dropwise to the TPE-2pTPA/P(VDF-HFP) nanofiber membrane, and the The fluorescence test was carried out, and the test results shown in Figure 3 were obtained. It can be seen from the figure that with the addition of PA solution, an obvious fluorescence quenching process can be observed, and the greater the concentration of PA, the more obvious the fluorescence quenching of the fiber, thus obtaining a PA solution of 1.0×10 ^-8 g/ mL, and the quenching efficiency is as high as 48.60% at this time (as shown in Figure 4). The quenching efficiency is calculated by the equation (I ₀ -I)/I ₀ , where I ₀ refers to the maximum fluorescence emission intensity of the nanofiber film when there is no quencher PA, and I refers to the maximum fluorescence emission intensity of the nanofiber film at a certain concentration of the quencher PA. Maximum fluorescence emission intensity of nanofibrous films.

Claims (4)

1. The detection method of "crocodile skin-like" fluorescent nanofibers to picric acid, the steps are as follows: Step 1: preparing a P(VDF-HFP) solution and a chloroform solution of TPE-2pTPA, and then mixing the two to prepare a TPE-2pTPA/P(VDF-HFP) solution; Step 2: Place the TPE-2pTPA/P(VDF-HFP) solution in a low temperature environment in the refrigerator for seven days; Step 3: Electrospinning the treated TPE-2pTPA/P(VDF-HFP) solution to prepare a TPE-2pTPA/P(VDF-HFP) nanofiber membrane with "crocodile skin shape"; Step 4: Gradually add different concentrations of PA solutions to the "crocodile skin-like" TPE-2pTPA/P(VDF-HFP) nanofiber membrane for detection; Wherein, the mass fraction of TPE-2pTPA/P(VDF-HFP) solution in step 1 is 5%, that is, the mass ratio of TPE-2pTPA to P(VDF-HFP) is 5:95. 2. " crocodile skin shape " fluorescent nanofiber according to claim 1 is to the detection method of picric acid, it is characterized in that the method for preparing P (VDF-HFP) solution in step 1 is as follows: Mix acetone and N,N-dimethylacetamide at a ratio of 7:3 by volume to obtain a mixed solvent, then mix P(VDF-HFP) with the mixed solvent at a mass ratio of 13:87, and at 50°C Stir and dissolve for 12h (hours) to obtain a P(VDF-HFP) solution. 3. " crocodile skin shape " fluorescent nanofiber according to claim 1 is to the detection method of picric acid, it is characterized in that the method for preparing TPE-2pTPA chloroform solution in step 1 is as follows: Dissolve 0.2 g of TPE-2pTPA in 1 mL of chloroform solution to obtain a nearly saturated solution of TPE-2pTPA. 4. The detection method of "crocodile skin-like" fluorescent nanofibers for picric acid according to claim 1, characterized in that the voltage in the electrospinning process of step 2 is 15kV, the advancing speed of the syringe is 0.002mm/s, and the receiving device It is a 29.2cm×29.2cm stainless steel receiving plate and a 2.5cm×7.5cm glass slide is attached to it.