CN114280115B - Photoelectrochemistry adaptive sensor, preparation method thereof and DBP detection method - Google Patents
Photoelectrochemistry adaptive sensor, preparation method thereof and DBP detection method Download PDFInfo
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Abstract
The invention discloses a photoelectrochemistry adaptive sensor, a preparation method thereof and a DBP detection method, wherein the photoelectrochemistry adaptive sensor comprises a conductive substrate, and CTAB@CH containing perovskite phase and fixed on the conductive substrate 3 NH 3 PbI 3 Layer covered on CTAB@CH 3 NH 3 PbI 3 An aptamer ATP layer on the layer. Wherein CTAB is used for passivation of CH by forming a protective layer 3 NH 3 PbI 3 Enhancement of CH by X-and A-site vacancies 3 NH 3 PbI 3 Is effective in improving photoelectric response and moisture resistance. CTAB also helps to immobilize nucleic acid aptamers by electrostatic interactions between cationic groups and the phosphate groups of the nucleic acid Aptamers (APT). After specific recognition of DBP, the DBP aptamer is released from the electrode due to its strong affinity for the introduced DBP, resulting in an enhancement of the photoelectric signal. CH of the invention 3 NH 3 PbI 3 Has good photoelectrochemistry characteristic and specific recognition capability of an aptamer, and the prepared PEC sensor has the linear range of 0.1 pmol.L ‑1 ‑10nmol·L ‑1 The detection limit and the quantitative limit are respectively as low as 2.5X10 ‑14 M and 8.2X10 ‑14 M(S/N＝3)。
Description
Technical Field
The invention relates to the technical field of photoelectrochemistry, in particular to a photoelectrochemistry adaptive sensor, a preparation method thereof and a method for detecting DBP.
Background
Dibutyl phthalate (DBP) is widely used in phthalate plasticizers because of its good gelling ability and cohesiveness. However, DBP is easily transferred from the surface of plastic articles to the environment because the interactions between DBP and plastic substrates are hydrogen bonds and van der waals forces rather than covalent bonds. Research reports that the widespread use and permanent emission of phthalates results in their accumulation in food products exceeding national standards. DBP, a typical emerging organic contaminant, after entering the human body, may disrupt endocrine, affect liver and urinary systems, increasing the risk of cardiovascular disease in humans. The potential and adverse effects of DBP on ecosystems and public health have attracted increasing attention and there is a need to develop simple, efficient, low cost, easy to operate and reliable methods to continuously and effectively monitor the residual amounts of DBP.
In recent years, simple and novel Photoelectrochemical (PEC) sensors have been developed for detecting various chemical components and biomolecules in environmental and biological samples. The PEC sensor has the characteristics of optical and electrochemical analysis, and has the advantages of low cost, quick response, high sensitivity, low background and simple preparation process. The introduction of recognition elements has received considerable attention in order to increase PEC selectivity. The antibody is suitable for rapid monitoring and screening of different targets, but the preparation of the antibody is a complex and time-consuming process, and the use of the antibody as a recognition probe has the problems of high cost, long reaction time and the like. ATP is an artificially synthesized short-chain oligonucleotide fragment that can specifically recognize proteins, small molecules, and cells. They have better properties than antibodies or receptor proteins in terms of preparation, cost, stability and modification.
The existing photoelectrochemical adaptive sensor does not combine ATP with a PCE sensor and is used for detecting DBP concentration, and the existing PEC sensor can form a large number of trap states on the grain boundary and the surface by organic-inorganic hybridization perovskite, so that non-radiative recombination is caused, and the efficiency and the stability of the sensor are harmful.
In order to solve the technical problems, the conventional method adopts additive engineering to solve passivation defects, and common additives comprise Lewis acid/alkali, long-chain polymers, organic metal frames, nano particles and the like, but the preparation processes of the methods are complex, and the PCE sensor has poor stability and low accuracy of detection results.
Disclosure of Invention
The invention aims to: the invention aims to provide a photoelectrochemical adaptive sensor with high stability, good anti-interference performance and high sensitivity; another object of the invention is to provide a method for manufacturing a photoelectrochemical adaptation sensor; it is another object of the present invention to provide a method of detecting DBP.
The technical scheme is as follows: the photoelectrochemistry adaptive sensor comprises a conductive substrate, a CTAB@CH containing perovskite phase and fixed on the conductive substrate 3 NH 3 PbI 3 Layer covered on CTAB@CH 3 NH 3 PbI 3 An aptamer ATP layer on the layer.
Further, the conductive substrate is ITO conductive glass.
Further, the sequence of the aptamer ATP is shown as SEQ No. 1.
SEQ No.1：5'-CTTTCTGTC CTTCCGTCACATCCCACGCATT CTCCACAT-3'
On the other hand, the preparation method of the photoelectrochemical adaptive sensor comprises the following steps:
(1) Pretreating a conductive substrate, and then modifying CTAB@CH on the conductive substrate 3 NH 3 PbI 3 Forming an electrode having a perovskite phase; the pretreatment of the conductive substrate comprises respectively ultrasonically cleaning the conductive substrate by toluene, acetone, ethanol and deionized water; modification of CTAB@CH 3 NH 3 PbI 3 The method is that CTAB@CH 3 NH 3 PbI 3 The precursor solution is dripped on the surface of the conductive substrate and dried;
(2) Modifying an aptamer ATP layer on the surface of the electrode to obtain the preparation; wherein the method of modifying the aptamer ATP layer is to coat the aptamer ATP on the electrode surface, and then dry and rinse.
Further, CTAB@CH in step (1) 3 NH 3 PbI 3 CTAB and CH in precursor solution 3 NH 3 PbI 3 The molar ratio of (C) is 4:1-6:1, and CH at the moment is the same as that of CH 3 NH 3 PbI 3 Ordered grain arrangement, CH 3 NH 3 PbI 3 The film has smooth and compact morphology, and fewer holes and cracks. Effective passivation of appropriate amount of CTAB reduces CH 3 NH 3 PbI 3 Non-radiative recombination of thin film, enhancement of CH 3 NH 3 PbI 3 Stability, helps to passivate defects, and improves CH 3 NH 3 PbI 3 The morphology of the film reduces cracking and roughness. This is because of QA cations and Br in CTAB - Partially replace or fill with CH 3 NH 3 PbI 3 A vacancy in position A or X; an excess of CTAB may inhibit CH 3 NH 3 PbI 3 And thus reduce the photoelectric conversion rate of PEC.
Further, CTAB@CH in step (1) 3 NH 3 PbI 3 The modification amount of the conductive substrate is 12.5-20 mu L/cm 2 。CH 3 NH 3 PbI 3 Film thickness can affect light collection and carrier recombination, with CTAB@CH 3 NH 3 PbI 3 The increase of the film thickness increases passivation defects, resulting in an increase of electron-hole recombination and a decrease of electron transfer rate.
Further, the ATP concentration in step (2) is 1.0. Mu.M to 2.5. Mu.M, and the immobilization time of ATP on the electrode is increased to 40 to 60 minutes. The photocurrent response of the sensor at this time is relatively stable.
In another aspect, the method of the invention for detecting dibutyl phthalate using a photoelectrochemical adaptation sensor includes incubating a dibutyl phthalate drop on the photoelectrochemical adaptation sensor.
Further, the dibutyl phthalate drop is incubated on the photoelectrochemical adaptive sensor for more than 40 minutes.
The present invention introduces CTAB with long alkyl chain, positively charged quaternary ammonium cation (QA) and negatively charged halogen bromide into perovskite precursor solution to increase CH 3 NH 3 PbI 3 Stability and performance of (c). CTAB can effectively deactivate CH 3 NH 3 PbI 3 And (c) the cationic and anionic defects of the organic and inorganic materials, thereby reducing non-radiative recombination. Furthermore, the long alkyl chain of CTAB is distributed in CH 3 NH 3 PbI 3 Surface can improve CH 3 NH 3 PbI 3 Is water-repellent and water-stable. CTAB modified CH 3 NH 3 PbI 3 Has better hydrophobicity and electron transfer capability, thereby improving the photoelectric signal of the PEC sensor. As a cationic surfactant, CTAB interacts with ATP via electrostatic forces between CTAB positively charged cations and ATP negatively charged phosphate ions. CTAB is often used to dissociate DNA from chromosomal proteins and to selectively precipitate nucleic acids. The successful use of CTAB in plant tissue has led to its use in many other organisms where DNA extraction is difficult. The invention self-assembles CTAB on CH 3 NH 3 PbI 3 Surface to improve the hydrophobicity and photoelectrochemical properties of PEC sensors.
The beneficial effects are that: compared with the prior art, the invention has the following remarkable advantages:
(1) The aptamer sensor has the advantages of high response speed, stable photocurrent, simple preparation process and satisfactory selectivity, reproducibility and stability in DBP detection and actual sample analysis;
(2) The aptamer sensor has high anti-interference performance, high specificity and high sensitivity, and the linear range is 0.1 pmol.L -1 -10nmol·L -1 The DBP detection limit and the quantitative limit are respectively as low as 2.5X10 -14 M and 8.2X10 -14 M (S/N=3), detection limit is as low as 25fmol · L-1 。
Drawings
FIG. 1 is a schematic diagram of the PEC aptamer sensor construction process and DBP assay mechanism of the invention;
FIG. 2 is a chart of FT-IR and X-ray characterization in example 1:
fig. 3 is a SEM characterization diagram in example 1:
fig. 4 is a graph of photocurrent test results in example 1:
FIG. 5 is a steady state fluorescence plot and intensity modulated photovoltage spectrum of example 1
FIG. 6 is a graph showing the results of the electrochemical impedance spectroscopy test of example 1,
FIG. 7 is a graph of CTAB@CH at different CTAB concentrations in example 2 3 NH 3 PbI 3 ITO scanning electron microscope;
FIG. 8 is H in example 2 3 NH 3 PbI 3 Transient photocurrent response in the presence of different CTABs;
FIG. 9 is a graph of the photocurrent response of PEC aptamer sensors prepared by example 2 optimizing different conditions;
FIG. 10 is a graph showing the effect of PEC aptamer sensor quantification of DBP in example 3:
Detailed Description
The technical scheme of the invention is further described below with reference to the accompanying drawings.
Example 1
As shown in FIG. 1, the photoelectrochemical adaptive sensor of the invention comprises ITO conductive glass, CTAB@CH fixed on a conductive substrate 3 NH 3 PbI 3 Layer coated on CTAB@CH 3 NH 3 PbI 3 An aptamer ATP layer on ITO. Wherein the sequence of the aptamer ATP is shown in SEQ No. 1: 5'-CTTTCTGTC CTTCCGTCACATCCCACGCATT CTCCACAT-3'.
Specifically, CTAB self-assembly in CH 3 NH 3 PbI 3 The surface improves the hydrophobicity and photoelectrochemical properties of the PEC sensor. In addition, the positive charge of CTAB and the halogen atom also contribute to the aptamer at CH 3 NH 3 PbI 3 And (3) assembling. CTAB acts as a photosensitive Material CH 3 NH 3 PbI 3 And DBP aptamer, a PEC aptamer sensor for detecting DBP in an environment is constructed. The release behavior of the aptamer is combined with the excellent properties of the perovskite, and DBP can be accurately detected. Once DBP is introduced, it will be identical to ATP reacts, which alters the conformation of ATP, thereby impairing the interaction between the aptamer and CTAB. ATP will be derived from the photosensitive material CH 3 NH 3 PbI 3 Surface separation results in recovery of photocurrent. Signal enhancement strategies can reduce false positive readings and improve the immunity of PEC sensors.
The preparation method of the photoelectrochemical adaptive sensor comprises the following steps:
(1) Conductive substrate pretreatment and precursor solution preparation
Treatment of an ITO conductive substrate: firstly, cutting ITO conductive glass into a regular shape of 1cm multiplied by 2cm by using a glass cutter, and then respectively ultrasonically cleaning the ITO conductive glass for 15min by using toluene, acetone, ethanol and deionized water to remove residual organic matters and stains on the surface of the conductive glass. The cleaned ITO glass was dried in a nitrogen stream for further use.
CH 3 NH 3 PbI 3 The specific synthesis method is as follows: 2.4mM PbI 2 And 2.0mM CH 3 NH 3 I was dispersed in 2.0mL DMF. Magnetically stirring at 70deg.C for 6h to ensure PbI 2 And CH (CH) 3 NH 3 I is completely dissolved. Obtaining yellow solution, namely CH 3 NH 3 PbI 3 A precursor solution.
CTAB@CH 3 NH 3 PbI 3 Preparation of the precursor solution: by CH obtained as described above 3 NH 3 PbI 3 CTAB of different masses was added to the precursor solution so that CTAB concentrations were 1.0mg/mL, 1.5mg/mL, 2.0mg/mL, 2.5mg/mL and3.0mg/mL, respectively, and the mixture was magnetically stirred for 1 hour at 70℃to prepare CTAB@CH 3 NH 3 PbI 3 A precursor solution.
(2) Construction of PEC aptamer sensor: 15. Mu.L of CTAB@CH 3 NH 3 PbI 3 The precursor solution was dropped on the ITO surface (the working area of the ITO electrode was fixed at 1.0 cm. Times.1.0 cm), and dried in a forced air oven at 60℃for 6 hours. The color of the film changed from yellow to black, indicating the formation of the perovskite phase. Then, 10. Mu.L of ATP at the desired concentration was coated on CTAB@CH 3 NH 3 PbI 3 On the ITO electrode. Electric powerThe pole was dried at room temperature for 40 minutes to ensure effective immobilization of the aptamer. The electrode was then rinsed thoroughly with PBS to remove loosely immobilized aptamer. Finally, the prepared ATP/CTAB@CH 3 NH 3 PbI 3 ITO was stored in a refrigerator at 4 ℃ for further application.
Characterization experiments: fourier transform infrared spectroscopy (FT-IR) test: FIG. 2 is a chart of FT-IR and X-ray characterizations, where (A) is the Fourier transform IR spectrum of CH3NH3PbI3 (curve a) and CTAB@CH3NH3PbI3 (curve B) films and (B) is the X-ray diffraction pattern of CH3NH3PbI3 films and CH3NH3PbI3 films with added CTAB at concentrations of 1.0mg/mL, 1.5mg/mL, 2.0mg/mL, 2.5mg/mL, and3.0 mg/mL.
As shown in FIG. 2A, 3031-3170cm -1 The broad absorption band at this location is attributed to the N-H telescopic vibration signal of the amine salt. 2901cm -1 (ν s CH 2 ) And 2973cm -1 (ν as CH 2 ) Absorption peak and CH in the vicinity 2 Is related to the symmetrical and antisymmetric vibration modes. 1602cm -1 And 1464cm -1 The absorption peaks at this point are derived from the N-H bending vibration of the amino group and the C-H bending vibration of the alkane. 949cm-1 and 1248cm -1 Where the broad absorption band is designated NH 3 And (5) swinging and vibrating. 905cm -1 And 622cm -1 The absorption peak at this point is derived from the methyl function and the rocking vibration of N-H. Notably, in CTAB@CH 3 NH 3 PbI 3 1051cm was observed in the middle -1 The absorption peak at this point is derived from C-N stretching vibration in CTAB molecules. Furthermore, 2973cm -1 、1602cm -1 And 1464cm -1 The intensity of the peak increases. This is due to the-N-CH corresponding to CTAB molecules 3 Partial N-H and C-H vibration, which confirms the presence of CTAB and CH 3 NH 3 PbI 3 The bonding reaction with CTAB occurs during the modification process.
XRD test: as shown in fig. 2B, XRD patterns of all samples showed significant CH at 2θ values of 14.1 °, 28.4 °, 31.9 °, 40.7 °, 43.2 ° and 50.3 ° 3 NH 3 PbI 3 Diffraction peaks corresponding to (110), (220), (310), (224), (314) and (400) crystal planes, respectively. This shows that the addition of an appropriate amount of CTAB does not introduce impurity phases norWill change CH 3 NH 3 PbI 3 Crystal structure of the thin film. Notably, the peak intensities of the (110) and (200) crystal planes varied with increasing CTAB concentration. In all samples, 2.0mg/mL CTAB@CH 3 NH 3 PbI 3 The film showed the strongest diffraction peak intensity, indicating CH 3 NH 3 PbI 3 The crystallinity of (c) is improved. With further increases in CTAB concentration, the diffraction peak intensity of the perovskite was significantly reduced, probably because the excess CTAB inhibited PbI 2 To CH 3 NH 3 PbI 3 Is transformed by the above method. The long alkyl chain in CTAB has insulation property, and excessive CTAB can reduce CH 3 NH 3 PbI 3 Crystallinity and photovoltaic properties of the films. This suggests that CTAB at a concentration of 2.0mg/mL is more advantageous for CH enhancement 3 NH 3 PbI 3 Is a performance of the (c).
Scanning Electron Microscope (SEM) characterization: as shown in FIG. 3, wherein CH 3 NH 3 PbI 3 /ITO(A)CTAB@CH 3 NH 3 PbI 3 ITO (B) and ATP-CTAB@CH 3 NH 3 PbI 3 Scanning electron microscope of ITO (C); illustration of CH 3 NH 3 PbI 3 /ITO(a)、CTAB@CH 3 NH 3 PbI 3 ITO (b) and ATP/CTAB@CH 3 NH 3 PbI 3 Low-power scanning electron microscope of ITO (c); (D) Is ATP/CTAB@CH 3 NH 3 PbI 3 Element distribution diagram of ITO;
and CH (CH) 3 NH 3 PbI 3 CTAB@CH compared to ITO (FIG. 3A) 3 NH 3 PbI 3 ITO (fig. 3B) has a denser, smoother surface with less crack and pinhole density. CTAB layer will interact with CH by Van der Waals interactions 3 NH 3 PbI 3 Surface realization. Br of CTAB - Will vertically adhere to CH 3 NH 3 PbI 3 Middle and compensate I - Vacancy leading to CH 3 NH 3 PbI 3 The lattice contracts, thereby enhancing interactions between organic and inorganic species and reducing non-radiative recombination. FIG. 3C shows that when ATP is immobilized on CTAB@CH 3 NH 3 PbI 3 Electrode for ITOThere is a thin film on the surface and the electrode morphology changes slightly at low resolution (figure 3C interpolated diagram). This film may be a fixed ATP. By detecting APT/CTAB@CH 3 NH 3 PbI 3 The elemental distribution of ITO found the presence of P element (FIG. 3D), which demonstrates that ATP has been successfully adsorbed to CTAB@CH 3 NH 3 PbI 3 ITO surface.
Photocurrent testing: CH is detected under irradiation of visible light 3 NH 3 PbI 3 ITO and CTAB@CH 3 NH 3 PbI 3 ITO at 0.1M Na 2 SO 4 Photocurrent in the solution. As shown in FIG. 4, wherein curve a is CH 3 NH 3 PbI 3 Photo-current response of ITO, curve b is CTAB@CH 3 NH 3 PbI 3 Photocurrent response of ITO; CH (CH) 3 NH 3 PbI 3 The photocurrent of/ITO (curve a) retained only 22.95% of its initial current during the 400s detection time, while ctab@ch 3 NH 3 PbI 3 The photocurrent of/ITO (curve b) remained 97.48%. Notably, during the photoelectric detection process, when CH 3 NH 3 PbI 3 when/ITO is immersed in the electrolyte, CH 3 NH 3 PbI 3 Is easily decomposed and falls off from the electrode, thereby seriously affecting photoelectric conversion performance. CH (CH) 3 NH 3 PbI 3 Is an ionic solid exhibiting ion migration in the electrolyte, which phenomenon has also been demonstrated to be CH 3 NH 3 PbI 3 The way of degradation. Ion migration at CH 3 NH 3 PbI 3 Defects and larger voids are created in the grain boundaries of (c) and have a significant effect on the photocurrent. After CTAB modification, CH 3 NH 3 PbI 3 The film exhibits excellent stability. In one aspect, br in CTAB - Can be incorporated into Pb-I lattices, which can effectively reduce inherent defects and passivate CH 3 NH 3 PbI 3 Is a surface of the substrate. On the other hand, the long alkyl chain in CTAB molecule is anchored to CH 3 NH 3 PbI 3 On the crystal, a protective layer is formed. As self-assembled monolayer (SAM) hydrophobic insulating layer, CH 3 NH 3 PbI 3 On the surface and grain boundaryThe CTAB of (C) can effectively inhibit moisture penetration and improve the stability of the device. Therefore, CTAB is not only beneficial to improving the morphology and passivation defect of perovskite crystal grains, but also can effectively protect CH 3 NH 3 PbI 3 Is protected from moisture attack, thereby improving the stability and water resistance of PEC aptamer sensors.
Steady state Photoluminescence (PL) and intensity modulated photovoltage spectroscopy (IMVS) test: as shown in fig. 5, wherein: (A) Is CH 3 NH 3 PbI 3 (Curve a) and CTAB@CH 3 NH 3 PbI 3 Steady state fluorescence plot of (curve b); (B) Is CH 3 NH 3 PbI 3 ITO (curve a) and CTAB@CH 3 NH 3 PbI 3 Intensity modulated photovoltage spectrum of ITO (curve b); and CH (CH) 3 NH 3 PbI 3 (FIG. 5A, curve a) compared with CTAB@CH 3 NH 3 PbI 3 The PL intensity (curve b) of (C) is obviously enhanced, which shows that the addition of CTAB can greatly improve CH 3 NH 3 PbI 3 Non-radiative recombination of thin films. Notably, with CH 3 NH 3 PbI 3 In contrast, CTAB doped CH 3 NH 3 PbI 3 PL spectra of the films showed a significant blue shift. Similar to the previous reported results, small grain perovskite results in perovskite crystals that blue shift in magnitude inversely proportional to crystal size. IMVS is the response of the detected photocurrent to the light intensity modulation at the open circuit voltage. FIG. 5B shows CH 3 NH 3 PbI 3 (Curve a) and CTAB@CH 3 NH 3 PbI 3 A typical Nyquist plot of (curve b). Using the formula τ d ＝1/2πf min The electron recombination time τd, f can be obtained min The characteristic frequency corresponding to the minimum value at the semicircle of the angular frequency. CH (CH) 3 NH 3 PbI 3 The compounding time of (2) was 194.18ms and increased to 275.83ms after the addition of CTAB. The increased electron lifetime suggests that CTAB can delay CH 3 NH 3 PbI 3 The non-radiative recombination between the free electrons of the conduction band and the free holes of the valence band ensures the effective excitation, dissociation and transmission of the electrons and the holes before the reaction with the target molecules.
Electrochemical Impedance Spectroscopy (EIS): as shown in FIG. 6, wherein FIG. 6A shows Nyquist plot for different modified electrodes, FIG. 6B shows photocurrent signal for different modified electrodes, wherein curve a is CTAB@CH 3 NH 3 PbI 3 ITO, curve b is ATP/CTAB@CH 3 NH 3 PbI 3 ITO curve c is 10 -8 M DBP/ATP/CTAB@CH 3 NH 3 PbI 3 ITO. In FIG. 6A, CTAB@CH is observed 3 NH 3 PbI 3 ITO (curve a) has good conductivity, indicating CTAB modified CH 3 NH 3 PbI 3 The electrode has good charge transfer characteristics. CTAB can effectively deactivate CH 3 NH 3 PbI 3 The probability of electron and hole recombination is reduced, and the electron transfer efficiency is improved. However, in CTAB@CH 3 NH 3 PbI 3 After introducing ATP on the ITO electrode (curve b), the Ret value increases significantly. The negatively charged phosphate groups of ATP largely block the redox probe [ Fe (CN) 6 ] 3-/4- Resulting in a significant increase in Ret. DBP in APT/CTAB@CH 3 NH 3 PbI 3 After incubation on the/ITO electrode (curve c), the Ret value decreases. This is due to the destruction of ATP and CTAB@CH after DBP binds to ATP 3 NH 3 PbI 3 Affinity between ITO electrodes, resulting in aptamer from CTAB@CH 3 NH 3 PbI 3 The ITO electrode surface dissociates. Thus, the amount of ATP on the electrode surface is reduced, and the Ret value is lowered. These results confirm the successful preparation of PEC aptamer sensors.
To investigate the feasibility of PEC aptamer sensors for DBP detection, fig. 6B shows the detection of photocurrent signals of different modified electrodes. CTAB@CH 3 NH 3 PbI 3 The ITO (curve a) shows a photocurrent intensity of 9.57. Mu.A. This is due to CH 3 NH 3 PbI 3 Excited under illumination, photo-generated electrons from CH 3 NH 3 PbI 3 The Valence Band (VB) is transported to the Conduction Band (CB) while holes remain on VB, forming electron-hole pairs. Photogenerated electrons and electron acceptors (O) 2 ) React and oxidize to H 2 O. Holes are driven to the ITO surface and trapped by electrons to generate photocurrent. Modified by CTABQA and CH of CTAB 3 NH 3 PbI 3 Pb not coordinated on 2+ (dangling bond) interactions eliminate non-coordinated Pb 2+ Thereby accelerating the transfer of photogenerated electrons to electron acceptors, facilitating the separation of electron-hole pairs and enhancing photocurrent response. When ATP is immobilized on the electrode (curve b), the photocurrent decreases significantly. This is because ATP is mainly composed of insulated nucleic acid molecules, has a steric hindrance effect, and inhibits the absorption of visible light and the transfer of electrons. When the PEC aptamer sensor is immersed 10 -8 When in M DBP solution (Curve c), it was immobilized on CTAB@CH 3 NH 3 PbI 3 ATP on ITO binds specifically to DBP molecules, reducing the affinity between ARP and electrode, resulting in release of ATP from the electrode surface. As the DBP concentration increases, the photocurrent signal recovers and increases.
Example 2 optimization experiments
To construct a highly efficient, stable, sensitive PEC aptamer sensor, the concentration of CTAB, ctab@ch 3 NH 3 PbI 3 Is optimized, the ATP concentration, the ATP binding time and the DBP incubation time.
CTAB is to increase CH 3 NH 3 PbI 3 Important substances for stability. It helps to passivate defects and improve CH 3 NH 3 PbI 3 The morphology of the film reduces cracking and roughness. However, an excess of CTAB may inhibit CH 3 NH 3 PbI 3 And thus reduce the photoelectric conversion rate of PEC. Thus, optimizing CH 3 NH 3 PbI 3 The concentration of CTAB is critical. In FIG. 7, (A), (B), (C), (D), (E) and (F) represent CTAB@CH at concentrations of 0.5, 1.0, 1.5, 2.0, 2.5and3.0mg/mLCTAB, respectively 3 NH 3 PbI 3 ITO scanning electron microscope image, CH can be clearly observed 3 NH 3 PbI 3 The grain size of (c) decreases gradually with increasing CTAB concentration. CH when the concentration was increased to 2mg/mL 3 NH 3 PbI 3 Ordered grain arrangement, CH 3 NH 3 PbI 3 The film has smooth and compact morphology, and fewer holes and cracks. However, withFurther increases in CTAB concentration, although CH 3 NH 3 PbI 3 Smaller grain size, but CH 3 NH 3 PbI 3 There are more holes and cracks in the film. Local aggregation of grains leads to CH 3 NH 3 PbI 3 The morphology of the film is poor, which may lead to degradation of the PCE. Obviously, 2.0mg/mL of CTAB-doped perovskite precursor solution can effectively reduce defect density and improve crystallinity of the perovskite layer, thereby leading to CTAB@CH-based 3 NH 3 PbI 3 With optimal efficiency.
For this purpose, as shown in FIG. 8, CH has been studied 3 NH 3 PbI 3 Transient photocurrent response in the presence of different CTABs. On CH 3 NH 3 PbI 3 The photocurrent was greatest when 2.0mg/mL CTAB was added to the precursor solution and decreased when the CTAB concentration was further increased. The results were similar to those shown by XRD and SEM data. Indicating that in CH 3 NH 3 PbI 3 The addition of 2.0mg/mL CTAB to the precursor solution allows CH to be formed 3 NH 3 PbI 3 The thin film has an optimal photoelectric conversion rate. This is because of QA cations and Br in CTAB - Partially replace or fill with CH 3 NH 3 PbI 3 A vacancy in position A or X. Effective passivation of appropriate amount of CTAB reduces CH 3 NH 3 PbI 3 The film is non-radiative composite, thereby effectively transmitting photoexcitation electrons and improving the conductivity of the film. Thus, the optimal CTAB concentration for constructing the PEC aptamer sensor was 2.0mg/mL.
FIG. 9 shows photo-current response of PEC aptamer sensor prepared for optimizing different conditions, wherein (A) is CTAB@CH 3 NH 3 PbI 3 (B) is ATP concentration, (C) is ATP binding time and (D) is DBP incubation time. Error bars from standard deviation of five measurements;
CH 3 NH 3 PbI 3 the thickness of the thin film is critical to the practical application of PEC sensors, as it can affect light collection and carrier recombination. As shown in fig. 9A, with ctab@ch 3 NH 3 PbI 3 Volume increase, photocurrent responseSlowly increasing, the current drops significantly as the volume increases further. With CTAB@CH 3 NH 3 PbI 3 An increase in film thickness will introduce more defects and result in fast electron-hole recombination and low electron transfer rates. Thus, the optimized CTAB@CH 3 NH 3 PbI 3 The volume was 15. Mu.L.
The concentration of ATP and the fixation time on the electrode are also critical to the performance of PEC aptamer sensors. FIG. 9B shows that CTAB@CH when the ATP concentration is increased from 0.1. Mu.M to 1.0. Mu.M 3 NH 3 PbI 3 The photocurrent response of the/ITO electrode drops rapidly, and is more stable when the ATP concentration increases from 1.0 μm to 2.5 μm. The results indicate that the ATP loaded on the electrode surface has reached saturation. Fig. 9C shows that as the fixed time of ATP on the electrode increases, the photocurrent decreases. When the fixing time is prolonged to 40-60 minutes, the photo current value tends to be stable. Thus, the concentration of ATP was 1.0. Mu.M, and the immobilization time between ATP and electrode was 40 minutes.
To quantitatively evaluate the response of the sensor to DBP, the incubation time of DBP on the aptamer sensor was also optimized. The photocurrent difference (Δi) before and after 10.0nM DBP incubation was taken as the net PEC response. As shown in fig. 9D, the Δi value of the aptamer sensor increased with increasing incubation time and tended to stabilize after 40 minutes. Indicating that the specific binding of ATP to DBP reaches saturation. Thus, the optimal incubation time for DBP is 40 minutes.
Example 3 quantitative detection of DBP
According to the optimal conditions optimized in example 3, i.e. CTAB@CH 3 NH 3 PbI 3 The PEC aptamer sensor was prepared in the same manner as in example 1 except that the volume was 15 μl, the concentration of ATP was 1.0 μm, the fixation time of ATP to the electrode was 40 minutes, and the incubation time of DBP was 40 minutes.
The PEC aptamer sensor thus prepared was used for quantitative detection of DBP, and the results are shown in FIG. 10, wherein (A) is the concentration of DBP (a to j:0.1 pmol.L -1 -10.0nmol·L -1 ) Transient photocurrent response under incubation; (B) Aptamer sensing for PECA calibration curve of photocurrent variation (Δi) versus logarithm of DBP concentration; (C) For selective detection of PEC aptamer sensors, the DBP concentration was 1.0nM and the interferent concentration was 10.0nM; (D) Is the stability of PEC aptamer sensors under continuous detection. Error bars are from standard deviation of three measurements.
FIG. 10A shows ATP/CTAB@CH 3 NH 3 PbI 3 PEC response of ITO electrode to different concentrations of DBP. The photocurrent increased with increasing DBP concentration, indicating more ATP bound specifically to the DBP molecules and released from the electrode surface. FIG. 10B shows that the logarithmic of the photocurrent change value (ΔI) and DBP concentration of the PEC aptamer sensor was 0.1 pmol.L -1 -10nmol·L -1 Has good linear relation in the range. The linear regression equation was ΔI (μA) =8.5216+0.6327 lgC (mol.L) -1 )(R 2 = 0.9956). Calculated to have a detection Limit (LOD) and a quantification Limit (LOQ) of 25 fmol.L, respectively -1 And 85 fmol.L -1 (S/n=3). Compared to the previously reported DBP detection method (table 1), the proposed PEC aptamer sensor showed a lower detection limit, indicating that the sensor prepared according to the invention has a higher sensitivity.
Sensor performance test: PEC detection and EIS detection
PEC and EIS tests use a three electrode system. The working electrode is a modified ITO electrode, and the Ag/AgCl electrode and the Pt electrode are a reference electrode and a counter electrode respectively. Contains Na 2 SO 4 An aqueous solution of (0.1M, pH 7.0) was used as the electrolyte. In PEC experiments, a white light source was used as the visible light irradiation source. The wavelength of this light is in the visible region (564.+ -.60 nm). The distance between the light source and the working electrode was 15 cm. The time for turning on and off the lamp was 20s. The current time (I-t) curve is recorded at a bias potential of 0.0V. For the DBP assay, 10 μl of DBP at different concentrations was dropped onto the electrode surface and incubated for 40min at room temperature. The electrode was then rinsed with PBS and placed in Na without DBP sample 2 SO 4 Photocurrent measurements were made in solution. EIS test was performed in a solution containing 0.1M KCl and 2.5mM [ Fe (CN) 6 )] 3-/4- The results are shown in fig. 10, where (a) is the PEC aptamer sensor at different concentrations of DBP (a to j:0.1pmol·L -1 -10.0nmol·L -1 ) Transient photocurrent response under incubation; (B) A calibration curve that is a logarithm of the photocurrent variation value (Δi) of the PEC aptamer sensor and the DBP concentration; (C) For selective detection of PEC aptamer sensors, the DBP concentration was 1.0nM and the interferent concentration was 10.0nM; (D) Is the stability of PEC aptamer sensors under continuous detection. Error bars are from standard deviation of three measurements.
To assess the selectivity of the PEC aptamer sensor, structural analogs, possible contaminants, and common interferents in the sample were selected for selective detection, such as DOP, DAP, DOTP, BPA. Under optimal conditions, the effect of these interferents was studied by analyzing 1.0nM DBP standard solution with 10.0nM interferents added. As shown in fig. 10C, all other disturbance-induced photocurrent variations are relatively small and negligible compared to the photocurrent variations caused by the DBP. It was demonstrated that ATP can bind specifically to DBP and cause a change in photocurrent signal. For other interferents, ATP cannot bind due to the lack of specific binding sites. This suggests that PEC aptamer sensors have satisfactory selectivity for DBP detection. Reproducibility of PEC aptamer sensors was assessed by the Relative Standard Deviation (RSD) of intra-and inter-batch detection. Three concentrations of DBP (10 nM, 1nM and 10 pM) were selected for measurement, for which the PEC aptamer sensor measured 3.24%, 4.61% and 5.32% of the in-batch RSD, respectively. Measurement of the same sample with 7 PEC aptamer sensors prepared under the same conditions also yielded 3.46%, 4.84% and 5.86% of inter-batch RSD. These results indicate that PEC aptamer sensors have good reproducibility. Figure 10D shows the stability of PEC aptamer sensors under continuous detection. Through 50 lamp on/off experiments, the photocurrent did not drop significantly, indicating that the PEC aptamer sensor had good stability.
Example 4 sensor determination of DBP concentration in Water sample
To assess the feasibility of PEC aptamer sensors in actual sample detection, the concentration of DBP in different water samples was studied. No DBP residue was detected in both water samples, probably because the DBP residue in both water samples was below the detection limit of the present method. Thus, further studies were performed using standard recovery methods. The performance of the aptamer sensor was evaluated by recovery and relative standard deviation by adding different concentrations of DBP standard solution to the water sample. The data in Table 1 show that DBP recovery is between 88.70% and 111.80% with RSD less than 4.39%. These results indicate that the PEC aptamer sensor prepared has higher reliability for actual sample analysis.
TABLE 1 concentration of DBP in different water samples by PEC aptamer sensor
Comparative example
The PEC aptamer sensor prepared in example 3 was compared with the performance of the DBP sensor of the comparative example, and the performance test method was the same as in example 3, and the specific results are shown in table 1. Wherein the DBP sensors in comparative examples 1 to 7 are cited from the following documents, respectively:
comparative example 1: rong, Y., et al, development of a bimodal sensor based on upconversion nanoparticles and surface-enhanced Raman for the sensitive determination of dibutyl phthalate in food. Journal of Food Composition and Analysis,2021.100.
Comparative example 2: liu, J.N., et al, liquid-Liquid interfacial self-assembled Au NP arrays for the rapid and sensitive detection of Butyl Benzyl Phthalate (BBP) by surface-enhanced Raman spectroscopy, analytical and Bioanalytical Chemistry,2018.410 (21): p.5277-5285.
Comparative example 3: zhu, N., et al, dual amplified ratiometric fluorescence ELISA based on G-quaterplex/hemin DNAzyme using tetrahedral DNA nanostructure as scaffold for ultrasensitive detection of dibutyl phthalate in aquatic system. Sci Total environment, 2021.784:p.147212.
Comparative example 4: zhou, q., et al, electrochemical sensor based on corncob biochar layer supported chitosan-MIPs for determination of dibutyl phthalate (DBP) Journal of Electroanalytical Chemistry,2021.897.
Comparative example 5: chen, Y., et al, A highly sensitive and group-targeting aptasensor for total phthalate determination in the environmental.J., hazard Mater,2021.412:p.125174.
Comparative example 6: li, J., et al, dual mode competitive electrochemical immunoassay for dibutyl phthalate detection based on PEI functionalized nitrogen doped graphene-CoSe2/gold nanowires and thionine-Au@Pt core-shell. Sensors and detectors B: chemical,2021.331.
Comparative example 7: wang, X., et al, detection of dibutyl phthalate in food samples by fluorescence ratio immunosensor based on dual-emission carbon quantum dot labelled aptamers. Food and Agricultural Immunology,2020.31 (1): p.813-826.
TABLE 2 comparison of the performance of PEC aptamer sensors constructed in accordance with the invention and DBP sensors in comparative examples 1-8
a SERS:Surface enhanced Raman spectrum； b MIP:Molecularly imprinted polymers； c DPV:Differential pulse voltammetry； d SWV:Square wave voltammetry； e CDs:Carbon quantum dots；
As can be seen from table 2, PEC aptamer sensors prepared according to the present invention performed significantly better than the DBP sensors of comparative examples 1-8.
The invention uses CTAB@CH 3 NH 3 PbI 3 The composite material is a light absorption platform, an aptamer is taken as an identification element, and an enhanced signal type PEC aptamer sensor is developed and used for detecting DBP, and is a well-known chemical substance interfering with human endocrine. CTAB as cationic additive, CH can be reduced 3 NH 3 PbI 3 Various ion defects in the film forming process improve crystallinity, refine grains and strengthen hydrophobicity. CTAB not only for improving CH 3 NH 3 PbI 3 But also between the phosphate group of the aptamer and the cationic group of CTABIs used to aid in the immobilization of the aptamer. The proposed aptamer sensor has high specificity and high sensitivity, and the detection limit is as low as 25 fmol.L -1 . Furthermore, the developed aptamer sensor has been successfully applied to the detection of DBP in environmental samples. The proposed sensing method is promising for simple, label-free and highly selective DBP detection, and may and can be used for detecting other PAEs in environmental samples.
Sequence listing
<110> university of Yangzhou
<120> a photoelectrochemical adaptation sensor, a method for preparing the same, and a method for detecting DBP
<160> 1
<170> SIPOSequenceListing 1.0
<210> 1
<211> 39
<212> DNA
<213> Artificial sequence (Artificial Sequence)
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ctttctgtcc ttccgtcaca tcccacgcat tctccacat 39
Claims (10)
1. A photoelectrochemistry adaptive sensor is characterized by comprising a conductive substrate, a CTAB@CH containing perovskite phase and fixed on the conductive substrate 3 NH 3 PbI 3 Layer covered on CTAB@CH 3 NH 3 PbI 3 An aptamer ATP layer on the layer; wherein by being in CH 3 NH 3 PbI 3 CTAB is added into the precursor solution to prepare CTAB@CH 3 NH 3 PbI 3 A precursor solution.
2. The photoelectrochemical sensor of claim 1, wherein the conductive substrate is ITO conductive glass.
3. The photoelectrochemical adaptive sensor according to claim 1, wherein the sequence of the aptamer ATP is shown in SEQ No. 1.
4. A method of manufacturing a photoelectrochemical adaptive sensor according to any of claims 1 to 3, comprising the steps of:
(1) Pretreatment of the conductive substrate, followed by modification of CTAB@CH thereon 3 NH 3 PbI 3 A layer forming an electrode having a perovskite phase;
(2) And (3) modifying an aptamer ATP layer on the surface of the electrode.
5. The method of manufacturing a photoelectrochemical adaptive sensor according to claim 4, wherein in step (1), the pretreatment of the conductive substrate includes ultrasonic cleaning of the conductive substrate with toluene, acetone, ethanol, deionized water, respectively.
6. The method for producing a photoelectrochemical sensor according to claim 4, wherein in the step (1), ctab@ch is modified 3 NH 3 PbI 3 The layer is prepared by CTAB@CH 3 NH 3 PbI 3 The precursor solution is dropped onto the surface of the conductive substrate and dried.
7. The method for preparing a photoelectrochemical adaptive sensor according to claim 6, wherein ctab@ch 3 NH 3 PbI 3 CTAB and CH in precursor solution 3 NH 3 PbI 3 The molar ratio of (2) is 4:1-6:1.
8. The method for preparing a photoelectrochemical adaptive sensor according to claim 4, wherein in the step (2), the method for modifying the aptamer ATP layer is to coat the aptamer ATP on the electrode surface, and then drying and washing.
9. The method for preparing a photoelectrochemical adaptive sensor according to claim 8, wherein the concentration of the aptamer ATP is 1.0 μm to 2.5 μm.
10. A method for detecting dibutyl phthalate using the photoelectrochemical adaptive sensor of claims 1-3, comprising incubating a dibutyl phthalate drop on the photoelectrochemical adaptive sensor.
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| Mechanistic Understanding of Cetyltrimethylammonium Bromide- Assisted Durable CH3NH3PbI3 Film for Stable ZnO-Based Perovskite Solar Cells;Yan Guo et al.;ACS Applied Energy Materials;第3卷(第10期);9856-9865 * |
| The improvement of inverted perovskite solar cells by the introduction of CTAB into PEDOT:PSS;Yu Zhu et al.;Solar Energy;第188卷;28-34 * |
| 基于纳米TiO_2和金纳米星的光电化学适配体传感器检测Hg~(2+)的研究;庄玉娇;巫仙群;王宇蕊;文勉;罗贵铃;孙伟;牛燕燕;;分析科学学报(01);116-120 * |
| 毒死蜱分子印迹光电化学传感器的制备及应用;金党琴 等;分析试验室;第40卷(第6期);703-707 * |
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