KR102351301B1 - Manufacturing Method For Fe3O4-PEI Nano Comosite Materials For Detecting Bisphenol A, Manufacturing Method For Fe3O4-PEI Nano Comosite Materials Sensor Electrode And Detecting Method For Bisphenol A - Google Patents

Abstract

The present invention relates to a method for manufacturing a Fe_3O_4-polyethylene imine (PEI) nanocomposite material for detecting bisphenol A, a method for manufacturing a Fe_3O_4-PEI nanocomposite sensor electrode for detecting bisphenol A, and a method for detecting bisphenol A by using the Fe_3O_4-PEI nanocomposite sensor electrode. Particularly, the method for manufacturing a Fe_3O_4-PEI nanocomposite material includes mixing Fe_3O_4 nanoparticles with PEI. The Fe_3O_4-PEI nanocomposite material obtained according to the present invention shows high sensitivity and excellent reproducibility and selectivity.

Description

Manufacturing method of Fe3O4-PEI nanocomposite material for detecting bisphenol A, method of manufacturing Fe3O4-PEI nanocomposite sensor electrode, and method of detecting bisphenol A PEI Nano Composite Materials Sensor Electrode And Detecting Method For Bisphenol A}

The present invention bisphenol-A production method of detection for Fe ₃ O ₄ -PEI method of manufacturing a nano-composite material, bisphenol A is detected for Fe ₃ O ₄ nanocomposite -PEI sensor electrode and Fe ₃ O ₄ nanocomposite sensor electrode -PEI relates to a detection method using the bisphenol a, more particularly, to Fe ₃ O ₄ nanoparticles with Fe for a bisphenol a detection prepared by mixing polyethyleneimine (PEI) ₃ O ₄ -PEI method of manufacturing a nano-composite material, bisphenol a detecting for Fe ₃ O ₄ -PEI nanocomposite relates to a method of manufacturing a sensor electrode and a Fe ₃ O ₄ -PEI bisphenol a detection method using the nanocomposite sensor electrode.

Bisphenol A (BPA, 2,2-bis (4-hydroxy phenyl) propane) and its derivatives bisphenol-S, bisphenol-B, and bisphenol-Z are widely known endocrine disruptors. It can seriously affect the human biological reproductive system and lead to infertility. Numerous papers state that BPA can cause cancer cells, infertility, and thyroid problems in humans. Bisphenol A is an important monomer in the manufacture of polycarbonate (PC), epoxy resin (EP), food storage cans, and baby bottles that are in demand for bisphenol A production in the market. As a result, BPA production exceeds 6 million pounds per year. The worldwide use of BPA-based polymers has led to an increase in river pollution. Due to BPA exposure, many countries, including the EU, China and Malaysia, have banned the use of chemical species containing BPA in baby bottles. However, BPA has been widely used in the medical community as sealants, dental fillings, and dental appliances. This makes it difficult to manage human BPA exposure. Therefore, it is an urgent problem to find a simple and sensitive method for detecting trace amounts of BPA.

High Performance Liquid Chromatography (HPLC), Liquid Chromatography with Mass Spectrometry (LC-MS), Gas Chromatography-Mass Spectrometry (-MS), Surface Enhanced Raman Spectroscopy (SERS), Calorimetric Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP) -AES) and chemoluminescence immunoassay methods, and various chromatographic and spectroscopic techniques are currently used for detection. Although these techniques detect BPA, they have limitations such as equipment cost, maintenance cost, time-consuming process, complicated operation that requires experts, pretreatment process, and sample preparation. In overcoming these points in all scenarios, electrochemical sensors have recently attracted great attention from researchers for BPA quantification. Its advantages include excellent sensitivity, in situ operation, low cost, green process, sensing interface and fast electron transfer between target compounds. Therefore, it is important to develop low-cost, high-sensitivity materials for BPA detection.

Electrooxidation of BPA and other phenolic compounds is an irreversible process, and its oxide causes surface fouling of the electrode, which always affects the detection of BPA. To increase BPA sensitivity, several nanostructured CNTs and graphene and their hybrid composite materials have been used as sensing interfaces with high conductivity, large surface area, and high adsorption rate to date. Many studies are focusing on novel metals such as Au, Pt, Pd, Ag nanoparticles, and their CNTs and graphene composites for BPA detection. Recently, many papers have published MWCNT functionalized as an electrochemical sensing material, MWCNT coated with polymer, The focus is on quantum dots. However, CNTs, novel metals and their composite materials have problems such as high cost, irreversible adsorption, and lack of soil. Therefore, a low-cost, simple and sensitive material is needed for effective electrical analysis of BPA.

Korean Patent No. 10-0841778

Superparamagnetic Fe ₃ O ₄ nanoparticles can be used for BPA sensing applications because of their high adsorption capacity, easy fabrication, high surface chemistry, abundance, low cost, and good eco-friendly catalyst. In particular, in the sensitive detection of BPA, Fe ₃ O ₄ NP and its composite material may be used, and Fe ₃ O ₄ NP may be used as a BPA sensor.

BPA is a negatively charged organic molecule, and its oxidation peak is highly dependent on the adsorption of the sensing material interface that induces an anode peak current. Therefore, the surface charge of the sensing material plays an important role in the detection of BPA. _{In the present invention, the surface of Fe 3} O ₄ NPs was modified using a positively charged, water-soluble, amino group-rich, electrically active, non-toxic, and high adhesion polymer known as polyethylene amine (PEI) in the present invention, which induces a positive charge on the surface and BPA of adsorption was increased. This is the first report of a BPA sensor using _{Fe 3} O _{4 -PEI nanocomposite as a sensing material.} In this study, we propose a novel high-sensitivity electrochemical sensor for the detection of BPA in aqueous solution based on a surface-customized Fe ₃ O _{4 -PEI nanocomposite modified carbon electrode (C).} The BPA fabricated Fe ₃ O ₄ -PEI/C composite response signal was _{significantly strengthened than that of Fe 3} O ₄ /C and its original state, indicating that Fe ₃ O ₄ -PEI composite is an inexpensive and superior sensing material for BPA. suggest that it could be In addition, _{several parameters such as Fe 3} O ₄ -PEI concentration, pH effect, and injection rate effect on BPA oxidation were studied. The fabricated Fe ₃ O ₄ -PEI composite material showed high sensitivity and good repeatability and selectivity.

An embodiment of the present invention, Fe ₃ O ₄ -PEI nanocomposite method for detecting bisphenol A detection method comprises a first step of preparing _{Fe 3} O _{4 nanoparticles by a hydrothermal method;} a second step of dispersing the Fe ₃ O ₄ nanoparticles prepared in the first step in water; a third step of adding polyethyleneimine (PEI) to the mixture of the second step; a fourth step of stirring the mixture mixed in the third step and sonicating for 5 to 15 minutes; a fifth step of vibrating the sonicated mixture for 1 hour to 3 hours; a sixth step of obtaining a magnetic composite material through magnetic treatment on the mixture of the fifth step; a seventh step of washing the magnetic composite material obtained in the sixth step 3 to 5 times with ultrapure water to remove polyethyleneimine (PEI) not bound _{to Fe 3} O _{4 nanoparticles;} and an eighth step of vacuum-drying the magnetic composite material of the seventh step at 50°C to 70°C.

An embodiment of the present invention, Fe ₃ O ₄ -PEI nanocomposite method for manufacturing a sensor electrode _{for detecting bisphenol A, a first step of manufacturing Fe 3} O ₄ nanoparticles by a hydrothermal method; a second step of dispersing the Fe ₃ O ₄ nanoparticles prepared in the first step in water; a third step of adding polyethyleneimine (PEI) to the mixture of the second step; a fourth step of stirring the mixture mixed in the third step and sonicating for 5 to 15 minutes; a fifth step of vibrating the sonicated mixture for 1 hour to 3 hours; a sixth step of obtaining a magnetic composite material through magnetic treatment on the mixture of the fifth step; a seventh step of washing the magnetic composite material obtained in the sixth step 3 to 5 times with ultrapure water to remove polyethyleneimine (PEI) not bound _{to Fe 3} O _{4 nanoparticles;} an eighth step of vacuum drying the magnetic composite material of the seventh step at 50°C to 70°C; _{Fe 3} O ₄ -PEI nanocomposite prepared by the eighth step in ultrapure water as a solvent is mixed at a ratio of 1 mg/mL to 5 mg/mL (Fe ₃ O ₄ -PEI nanocomposite)/(ultra-pure water) to Fe A ninth step of preparing a ₃ O _{4 -PEI nanocomposite suspension;} A 10th step of drop-casting the _{Fe 3} O ₄ -PEI nanocomposite suspension prepared by the ninth step on the cleaned electrode; _{and an 11th step of evaporating the drop-cast Fe 3} O ₄ -PEI nanocomposite suspension in the 10th step in the atmosphere for 1 to 3 hours as a solvent.

The bisphenol A detection method using the _{Fe 3} O ₄ -PEI nanocomposite sensor electrode according to an embodiment of the present invention includes a first step of preparing _{Fe 3} O _{4 nanoparticles by a hydrothermal method;} a second step of dispersing the Fe ₃ O ₄ nanoparticles prepared in the first step in water; a third step of adding polyethyleneimine (PEI) to the mixture of the second step; a fourth step of stirring the mixture mixed in the third step and sonicating for 5 to 15 minutes; a fifth step of vibrating the sonicated mixture for 1 hour to 3 hours; a sixth step of obtaining a magnetic composite material through magnetic treatment on the mixture of the fifth step; a seventh step of washing the magnetic composite material obtained in the sixth step 3 to 5 times with ultrapure water to remove polyethyleneimine (PEI) not bound _{to Fe 3} O _{4 nanoparticles;} an eighth step of vacuum drying the magnetic composite material of the seventh step at 50°C to 70°C; _{Fe 3} O ₄ -PEI nanocomposite prepared by the eighth step in ultrapure water as a solvent is mixed at a ratio of 1 mg/mL to 5 mg/mL (Fe ₃ O ₄ -PEI nanocomposite)/(ultra-pure water) to Fe A ninth step of preparing a ₃ O _{4 -PEI nanocomposite suspension;} A 10th step of drop-casting the _{Fe 3} O ₄ -PEI nanocomposite suspension prepared by the ninth step on the cleaned electrode; _{An 11th step of evaporating the drop-casted Fe 3} O ₄ -PEI nanocomposite suspension in the 10th step in the atmosphere for 1 to 3 hours as a solvent; And a buffer solution having a pH in the range of 6 to 7 is injected into a solution containing bisphenol A, and the solution containing the bisphenol A and buffer is added to the Fe ₃ O ₄ -PEI nanocomposite material in which the solvent is evaporated in the 11th step. and a twelfth step of detecting bisphenol A using a cyclic voltammetric method by contacting them.

_{Method of manufacturing Fe 3} O ₄ -PEI nanocomposite material for detecting bisphenol A of the present invention, _{method of manufacturing Fe 3} O ₄ -PEI nanocomposite sensor electrode for detecting bisphenol A, _{and Fe 3} O ₄ -PEI nanocomposite sensor electrode In the method for detecting bisphenol A using _{a, the first step of preparing the Fe 3} O ₄ nanoparticles by hydrothermal method, a mixture of FeCl ₂ ·4H ₂ O and FeCl ₃ ·6H ₂ O is used as an iron precursor.

In addition, the Fe ₃ O ₄ -PEI nanocomposite has diffraction peaks of (111), (220), (311), (400), (511), (440) and (533) crystallization planes, and The spectrum of the Fe ₃ O ₄ -PEI nanocomposite has peaks at 1263 cm ^-1 , 1654 cm ^-1 , 2849 cm ^-1 , 2946.8 cm ^-1 and 3367.3 cm ^-1 with aliphatic NH stretching vibration, and also the Fe _{The surface charge value of the 3} O ₄ -PEI nanocomposite material is 30 mV to 40 mV.

_{Method of manufacturing Fe 3} O ₄ -PEI nanocomposite material for detecting bisphenol A of the present invention, _{method of manufacturing Fe 3} O ₄ -PEI nanocomposite sensor electrode for detecting bisphenol A, _{and Fe 3} O ₄ -PEI nanocomposite sensor electrode According to the bisphenol A detection method using It can be used as a chemical sensor.

1 shows a schematic diagram of Fe ₃ O ₄ -PEI nanocomposite preparation and electrochemical BPA detection thereof.
Figure 2 (A) is an XRD pattern, Figure 2 (B) is an FTIR-spectrum (inside: Fe-O region enlarged), Figure 2 (C) is Fe ₃ O ₄ Np and Fe ₃ O ₄ -PEI nanocomposite material Zeta potential images are shown.
3 shows high-resolution-XPS spectra in (A) Fe 2p, (B) O 1s, (C) C 1s, and (D) N 1s regions.
Figure 4 Field emission scanning electron morphology of _{Fe 3} O ₄ Np (A) and Fe ₃ O _{4 -PEI nanocomposite (C).} EDAX patterns of Fe ₃ O ₄ Np (B) and Fe ₃ O ₄ -PEI nanocomposites (D) are shown.
5 (A) Cyclic voltammograms of original C and Fe ₃ O ₄ -PEI/C nanocomposites in the presence of 5 mM [Fe(CN) ₆ ] ^3- in 0.1M KNO ₃ at a scan rate of 100 mVs ^{-1 .} (B and C) _{Scan rate variation range of original C and Fe 3} O ₄ -PEI/C from 20 to 200 mVs ⁻¹ (internal: linear regression plot of current vs. lnv). (D) Nyquist plots of original C and Fe ₃ O ₄ -PEI/C nanocomposites in the presence of 5 mM [Fe(CN) ₆ ] ^3- _{in 0.1 M KNO 3} (inner: inner figure is the low ohmic region) enlarged) is shown.
6 (A) CV response of C modified with each electrode material in PBS (pH 6.8) in the presence of 10 μM BPA at a scan rate of 100 mVs ^{-1 .} (B and C) CV behavior at each amount (mg) and loading (μl) of _{Fe 3} O ₄ -PEI in 10 μM BPA of a PB solution with an ^{injection rate of 100 mVs -1 .}
Figure 7 (A) CV pattern of 10 μM BPA in _{Fe 3} O ₄ -PEI/C at each solution pH (5, 6, 6.8, 8, 9) of ^{100 mVs -1 .} (B) Bipolar peak potential vs pH of 10 μM BPA. (C) Changes in scan rate of 10 μM BPA in _{Fe 3} O ₄ ^{-PEI/C (20–200 mVs −1} ). (D) Peak current (Ipa) vs scan rate of BPA. (E) Shows the peak potential (Epa) vs ln v of BPA.
Figure 8 (A) Injection rate: circulating voltammograms of _{Fe 3} O ₄ -PEI/C in 0.1 M PBS of each concentration BPA (0.01 μM-50 μM) at ^{100 mVs −1 .} (B) Calibration plot of each concentration of BPA. (C and D) of 100 at 10 μM BPA of ^{_{0.1M PBS mVs -1 Fe 3 O 4}} Fe 3 peak in CV and 10 μM BPA of 0.1M PBS solution of other interfering compounds from -PEI / C O ₄ -PEI / Stability of C (internal: _{CV pattern of Fe 3} O ₄ -PEI /C in 10 μM BPA and 500 μM 2,4-dinitrophenol in 0.1 M PBS at ^{100 mVs −1 ).}
Figure 9 (A) GC-MS reactions of 1, 3, 5, 8, and 10 μM BPA in real samples. (B) _{Comparison of BPA sensitivity according to Fe 3} O ₄ -PEI electrode and GC-MS method. GC-MS mass patterns of standard BPA (C) and real sample BPA (D) are shown.

The present invention bisphenol-A production method of detection for Fe ₃ O ₄ -PEI method of manufacturing a nano-composite material, bisphenol A is detected for Fe ₃ O ₄ nanocomposite -PEI sensor electrode and Fe ₃ O ₄ nanocomposite sensor electrode -PEI It provides a method for detecting bisphenol A using Through the following examples, it will be described in more detail.

(Example)

1.1 Chemicals and Measuring Instruments Used

As an iron precursor of the present invention, a mixture of FeCl ₂ .4H ₂ O and FeCl ₃ .6H ₂ O may be used. The mixing ratio of FeCl ₂ ·4H ₂ O and FeCl ₃ ·6H ₂ O may be 1:0.5 to 1.5 by mass. In this experiment, the iron precursor was obtained from Daejong Chemical (Korea). Bisphenol A (BPA) and polyethyleneimine (PEI) were purchased from Sigma-Aldrich (USA). A 0.1 mol/L BPA stock solution was prepared using ethanol and stored at 4°C. The phosphate buffer (PBS) of the present invention may be used in an amount of 0.01 mol/L to 0.5 mol/L, and 0.1 mol/L was used in this experiment. As the buffer of the present invention, a mixture of a compound of the following formula (1) and a compound of the formula (2) can be used. The mixing ratio of the compound of Formula (1) and the compound of Formula (2) may be 1:0.5 to 1.5 by volume.

Na ₂ HPO ₄ Formula (1)

NaH ₂ PO ₄ Formula (2)

Chemical formulas (1) and (2) were purchased from Samcheon Chemical (Korea). The pH of the buffer _{was maintained using phosphoric acid (H 3} PO ₄ ) and sodium hydroxide (NaOH). All solutions were prepared with double distilled water.

The _{crystallinity of Fe 3} O ₄ Np and Fe ₃ O ₄ -PEI nanocomposites was analyzed by XRD and D8 DISCOVER-BRUKER analyzers of Cu targets. Attenuated total reflection FTIR (ATR-FTIR, Thermo Fisher, Nicole iS5, USA) was used for functional group analysis. The XPS spectrum of the Fe ₃ O ₄ -PEI nanocomposite was observed with an X-ray & UV photoelectron spectrometer (XPS, Thermo Fisher, USA). The morphology and mapping images of Fe ₃ O ₄ and Fe ₃ O ₄ -PEI nanocomposites were obtained by field emission scanning electron microscopy (FE-SEM) JEOL at 15 kV acceleration together with energy dispersive X-ray (EDX). The surface charge of Fe3O4-PEI nanocomposite was analyzed using Malvern Zetasizer Nano ZS90. The GCMS technique was used for GC/MS equipped with an electron trap detector (Shimazu Q2010, Japan) to compare the sensitivity of real samples. An Elite 5ms column (60 m length × 250 μm diameter × 250 μm thickness) was used. ^{MS was monitored in EI +} mode at an electron energy of 70 eV, and selected ion monitoring was used to monitor m/z 213 (molecular weight of BPA). The heat source temperature was 250 °C and the GC transfer line was maintained at 280 °C. The GC oven temperature was programmed as such. 3 min at 50° C., increasing to 280° C. at ^{10° C. min −1 , increasing to 250° C. at 8° C. min -1} , and then held at 250° C. 1 ml min ^-1 He ₂ gas was used as carrier gas. The extract was automatically injected into the GC inlet at 100°C with a split ratio of 20:1. 1 μl sample and standard were injected 3 times.

1.2 Electrochemical Sensor Features

All electrochemical measurements were analyzed using a VersaSTAT 3 electrochemical workstation (AMETEK, USA) with a conventional three-electrode system. A Fe ₃ O ₄ -PEI/C modified electrode (5 mm) was used as a working electrode, platinum (Pt) was used as a counter electrode, and silver/silver chloride (Ag/Al) was used as a reference electrode. Cyclic voltammetry (CV) of the present invention was used for BPA sensors in 0.1M PBS buffer. The voltage range of 0.3 to 0.9V, which is a potential range, was monitored at ^{100 mVs -1 .}

Electrochemical impedance spectroscopy (EIS) experiments were used to understand the electron transfer process in a denatured electrode. This was obtained using 5 mM[Fe (CN) ₆ ] ^3- in 0.1M KNO ₃ in the frequency range of 10 ^-2 to 10 ^{5 HZ.} All BPA sensing operations were performed at room temperature.

1.3 Fe ₃ O ₄ -PEI nanocomposite material manufacturing

내지 70

에서 진공 건조하는 제8 단계;를 포함할 수 있다. _{The method for preparing Fe 3} O ₄ -PEI nanocomposite material for detecting bisphenol A of the present invention comprises: a first step of preparing _{Fe 3} O _{4 nanoparticles by hydrothermal method;} a second step of dispersing the Fe ₃ O ₄ nanoparticles prepared in the first step in water; a third step of adding polyethyleneimine (PEI) to the mixture of the second step; a fourth step of stirring the mixture mixed in the third step and sonicating for 5 to 15 minutes; a fifth step of vibrating the sonicated mixture for 1 hour to 3 hours; a sixth step of obtaining a magnetic composite material through magnetic treatment on the mixture of the fifth step; a seventh step of washing the magnetic composite material obtained in the sixth step 3 to 5 times with ultrapure water to remove polyethyleneimine (PEI) not bound _{to Fe 3} O _{4 nanoparticles;} and 50 the magnetic composite material of the seventh step.

to 70

An eighth step of vacuum drying in; may include.

Here, Fe ₃ O ₄ nanoparticles may have a size of 10 nm to 500 nm, and ultrasonic treatment and vibration treatment are _{for combining Fe 3} O ₄ nanoparticles with polyethyleneimine (PEI) and dispersing as fine particles, and vibration treatment is This can be done by applying a certain force to the solution or shaking the case containing the solution at regular intervals. Magnetic treatment can be achieved by using a material having magnetism. By the Fe ₃ O ₄ is not bonded to the nanoparticle of polyethyleneimine (PEI) to effectively removed by washing of the composite material can be obtained Fe ₃ O ₄ nanoparticles with a polyethyleneimine (PEI) composites that are combined strongly.

In this example, Fe ₃ O ₄ NPs were prepared by a hydrothermal method. The obtained Fe ₃ O ₄ NP was dispersed in water, and polyethyleneimine (PEI) was added to the _{Fe 3} O _{4 NP suspension.} For a while, 10 mg Fe ₃ O ₄ was stirred with 0.1% PEI solution, sonicated for 10 minutes, and then vibrated for 2 hours. After that, the obtained magnetic composite material was magnetically separated for 10 minutes, and the composite material was washed 3 times with ultrapure water. to remove the loosely bound PEI, and the composite material was vacuum dried at 60° C. overnight. The final Fe ₃ O ₄ -PEI composite powder was analyzed by electrochemical reactions for XRD, XPS, FE-SEM, FTIR and BPA detection. 2 mg Fe ₃ O ₄ -PEI was dispersed in 1 mL ultrapure water.

1.4 Electrode Fabrication

First, the electrode was polished on a polishing cloth sequentially with 0.3 μm and 0.05 μm alumina suspension, and the electrode was washed between each polishing step with ethanol and water, then sonicated in ethanol and water for 3 minutes and dried in the air. To build the Fe ₃ O ₄ -PEI thin film on the washed electrode, 10 μl Fe ₃ O ₄ -PEI suspension (2 mg/mL) was drop-cast with a micropipette. In the present invention, a thin film having a certain thickness can be obtained by drop casting without using spin coating. After the solvent was evaporated in the atmosphere for 2 hours, the fabricated Fe ₃ O ₄ -PEI/C sensor electrode was used for BPA detection, and for comparison, the original C and Fe ₃ O ₄ /C modified electrodes were prepared in the same way. . The fabricated electrodes were refrigerated when not in use. The fabrication of the Fe ₃ O ₄ -PEI-modified electrode and the detection of BPA are shown in FIG. 1 .

1.5 Actual Sample Preparation

Fresh sterilized milk was purchased at Lotte Mart (Jochiwon, Korea). Samples were diluted with 0.1 M PBS buffer. Each concentration of BPA 1,3,5,8 μM was added as standard addition method.

(Results and Discussion)

2.1 Material selection

In order to select the material for the BPA sensor electrode, _{the positive charge on the surface of the Fe 3} O ₄ -PEI nanocomposite was excited, which has a large surface area, low cost, easy synthesis, abundant in soil, and mainly magnetic.

2.2 Fe ₃ O ₄ - Characteristics of PEI nanocomposites

X-ray diffraction was analyzed to analyze the structure and purity of _{Fe 3} O ₄ and Fe ₃ O _{4 -PEI nanocomposites.} 2A shows the XRD patterns of _{Fe 3} O ₄ Np and Fe ₃ O _{4 -PEI nanocomposites.} Both spectrograms show similar diffraction peaks in the (111), (220), (311), (400), (511), (440), and (533) crystallization planes for _{Fe 3} O _{4 NPs.} The peak position was changed and the peak intensity decreased after PEI coating on the surface of the _{magnetic Fe 3} O ₄ NPs, which is due to the interaction between _{PEI and Fe 3} O _{4 NPs.}

ATR-FTIR was used to analyze the functional groups of the fabricated material at each wavenumber, and FIG. 2B shows FTIR spectra of _{Fe 3} O ₄ and Fe ₃ O _{4 -PEI dispersed in water.} The two FTIR spectra showed the characteristics of the Fe-O binding peak at 558 cm ^-1 . Confirmed. In addition, the internal figure shows the enlarged Fe-O bond and the water OH stretching frequency at 1633.7 cm ^-1 . In addition, the intensity of the _{Fe 3} O ₄ vibrational peak (558 cm ⁻¹ ) in the PEI-coated magnetic nanoparticles _{was lower than that of the original Fe 3} O ₄ , confirming the surface denaturation. In addition, Fe ₃ O ₄ -PEI spectrum demonstrated aliphatic NH stretching vibrations at 1263 cm ^-1 , 1654 cm ^-1 , 2849 cm ^-1 , 2946.8 cm ^-1 , and 3367.3 cm ^-1 . The peak at 1457 cm ^-1 suggests alkane CH bending. The FTIR data clearly confirmed that the _{Fe 3} O ₄ -PEI nanocomposite contains Fe-O bonds and has several -NH _{2 functional groups on the surface. In addition, the surface conversion of the fabricated Fe 3} O ₄ -PEI composite material was confirmed by monitoring the zeta potential, and the results are shown in FIG. 2C. The surface charges of PEI and Fe ₃ O ₄ were 42.9 mV and -32.52 mV, respectively, and the _{surface charge value of the PEI-modified Fe 3} O ₄ composite material increased significantly to +35.51 mV, which _{was -NH 2 on the Fe 3} O ₄ -PEI surface. It was confirmed that there are many functional groups. The XRD, FTIR, and zeta potential results confirmed the successful surface modification of _{Fe 3} O _{4 -PEI.}

X-ray photoelectron spectroscopy (XPS) was analyzed _{to understand the chemical interaction and orbital bonding of Fe 3} O ₄ -PEI nanocomposites, and the results are presented in FIG. 3 . The wide scan XPS spectrum ( FIG. SI 1 ) shows the presence of Fe, O, N, and C elements. Fe 2P region spectrum FIG. 3A shows two prominent peaks at 710.2 eV and 724 eV, respectively, and is associated with Fe 2p _3/2 and Fe 2p ½, respectively. The satellite peak of Fe 2p was observed at 718.1 eV. XPS spectrum of the O 1S region FIG. 3B shows one prominent metal-oxygen bond at 529 eV. XPS spectra of C 1s and N 1s regions FIG. 3 C & D showed peaks at 284.7 eV and 399 eV, respectively. This is due to the interaction with the magnetic Fe ₃ O _{4 nanoparticles of PEI.} The atomic proportions of the elements are given in (Table SI 1). XPS results confirmed the PEI polymer and the successful modified Fe ₃ O ₄ surface.

To understand the surface morphology, SEM, EDAX, and elemental mapping were _{analyzed for Fe 3} O ₄ NPs (A) and Fe ₃ O ₄ -PEI composites (C), and the results are shown in FIG. 4 . The Fe ₃ O ₄ (A) form showed the crystallization structure _{of Fe 3} O ₄ nanoparticles and the presence of Fe and O elements in the EDAX spectrum of Fe ₃ O _{4 NPs (B).} The Fe ₃ O ₄ -PEI (C) composite showed a semi-crystallized form with a linear distribution of PEI. The EDAX spectrum of the Fe ₃ O ₄ -PEI (D) composite material clearly confirmed the presence of C, N, Fe, and O. Elemental mapping images of Fe ₃ O ₄ NPs (A) and Fe ₃ O ₄ -PEI composites (B) are shown in different colors (Fig. SI 2.1 a & b), which are Fe ₃ O ₄ -PEI nano It further confirmed the successful transformation of the composite material.

2.3 Fe ₃ O ₄ -Electrochemical properties of PEI

Using cyclic voltammetry, _{the electron transfer process of the Fe 3} O ₄ -PEI-modified electrode was analyzed using 5 mM K ₃ [Fe (CN) ₆ ] ^3- _{in 0.1 M KNO 3} as an electrochemical redox probe. Figure 5A shows the Ferri-Ferro behavior of the original C (a) and Fe ₃ O _{4 -PEI (b).} In the original C, a well-defined redox peak appeared with a peak separation potential (Ep) of 132.12 mV. When the electrode _{was modified with Fe 3} O ₄ -PEI, a slightly decreased Ep value and an increase (Ip) of the peak current were observed, indicating that the Fe ₃ O ₄ -PEI composite material exhibited high conductivity and a wide range of _{Fe 3} O _{4 nanoparticles.} Because of the surface area, K ₃ [Fe (CN) ₆ ] ^3- between the electrode and K 3 [Fe (CN) 6 ] 3 indicates that it enhances the mediated electrons. Also, scan rate changes (20 mVs ⁻¹ to 200 mVs ⁻¹ ) were observed for the original and Fe ₃ O _{4 -PEI modified electrodes.} 5B and C show a linear relationship with the scan rate. A positive electrode to the source electrode of the linear coefficient (I pa) and a negative peak current (Ipc) can be seen that each of R ² = 0.97892 and R ² = 0.97059. The linear coefficients of the Fe ₃ O ₄ ^{-PEI modified electrode were R 2} =0.97492 and R ² =0.97254 for Ipa and Ipc. Electrochemical studies suggest that Fe ₃ O ₄ -PEI nanocomposite thin films allow favorable electron transfer for _{K 3} [Fe (CN) ₆ ] ^{3 -redox probes.} This can be attributed to the large number of positively charged species on the surface. In addition, we tried to understand the resistance of the electrode using electrochemical impedance spectroscopy (EIS). This experiment was performed using 5 mM K ₃ [Fe (CN) ₆ ] ^3- _{in 0.1M KNO 3} solution as a modified electrode with different materials in the frequency range of 10 ^-2 to 10 ^{5 HZ.} Figure 5D shows the Nyquist plots of the original C (a) and Fe ₃ O ₄ -PEI /C (b). Nearly linear lines are observed for the original C (curve a) and Fe ₃ O ₄ -PEI (curve b) modified electrodes at low frequencies, suggesting an electron diffusion process. A small semicircle pattern was observed at high frequencies, which is related to the electron transfer resistance (Rct). Impedance values of the original C is 9.38 kohm and, Fe ₃ O ₄ EIS (curve b) the impedance value of the modified electrode -PEI after coating was observed with 10.31 kohm, which the composite material produced Fe ₃ O ₄ -PEI the electromigration It shows that it can be accelerated quickly.

2.4 Fe ₃ O ₄ -Electrochemical behavior of BPA in PEI

Electro-oxidation of different electrodes and BPA was investigated using cyclic voltammetry in 10 μm BPA in 0.1M PBS solution (pH 6.8) with a potential range of 0.3 to 0.9 V, and the results are shown in FIG. 6A. Irreversible peaks were observed for all denatured electrodes. In the original C, a low oxidation peak current of 0.6 V was observed. The anode peak current of BPA was shown _{in Fe 3} O _{4 Np.} The modified C electrode increased than the original C electrode, and the Fe ₃ O ₄ -PEI modified C electrode showed a significant increase in peak current with a low oxidation potential (0.574V). These results show that Fe ₃ O ₄ -PEI-modified composites are sensitive electron mediators in the electrocatalytic oxidation of BPA. In addition, PEI enhances the adsorption of negatively charged BPA species to positively charged species. In addition, experimental parameters such as catalyst loading and concentration were optimized to increase BPA sensitivity as shown in FIGS. 6B & C . 1 mg, 2 mg, 3 mg, 3.5 mg Fe ₃ O ₄ -PEI nanoparticles were well dispersed in 1 mL DI water. Among them, 2 mg catalyst showed high anode peak current and potential response. Different amounts of catalyst (5 μl, 10 μl, 15 μl) were coated and analyzed for BPA sensitivity. The 10 μl coated electrode showed high BPA sensitivity. Therefore, it was selected as the optimal condition in the experiment.

2.5 Fe ₃ O ₄ -Optimize BPA oxidation in PEI

The pH value of the electrolyte solution (0.1 M PBS) is an important factor in BPA sensitivity. The pH 5-9 of the PBS solution was irradiated with a 10 μM BPA solution, and is shown in FIG. 7A to understand the BPA sensitivity. It can be seen that the anode peak current increases from pH 5 to 6.8 and decreases from pH 8 to 9. Neutral pH 6.8 showed the maximum sensitivity to BPA. It was clear from Fig. 7B that the peak potential changed negatively with increasing pH at a rate of 55.03 mV per pH. According to the linear regression equation E(V) = 0.96437 - 0.05503 pH (R ² = 0.97576), the slope value of 55.03 mV per pH correlated well with the theoretical value of 57.6 mV per pH, indicating that the same number of protons and electrons was oxidized to BPA. It implies that you are involved in the process. Therefore, neutral PBS (pH=6.8) electrolyte was selected to obtain high BPA sensitivity.

The effect of change in scan rate on BPA oxidation was analyzed and the results are presented in Figure 7C. Cyclic voltammetry of 10 μM BPA in 0.1M PBS of Fe ₃ O ₄ ^{-PEI-modified C electrode with scan rate range of 20-200 mVs -1} gram was shown. The BPA peak current increased linearly in the range of ^{20-200 mVs -1 .} In FIG. 7D , the bipolar peak current (Ipa) increased linearly with the square root of the scan rate according to the linear regression equation Ipa (μA) = 7.9613 X + 0.20987 (R ^{2 = 0.9784).} This suggests _{that BPA oxidation in Fe 3} O ₄ -PEI/C is a surface-controlled process, and FIG. 7E shows that the bipolar peak potential (Epa) of BPA changes positively with increasing scan rate. Epa increases linearly with ln v, and the linear relationship is ^{expressed as Epa(V) = 0.50138 X + 0.01978 (R 2} = 0.9482). It is known that the anodic peak potential (Epa) in an adsorption-controlled and completely irreversible electrode process is defined by the Laviron equation.

E _pa = E ⁰ + (RT/αnF) ln(RTK ⁰ /αnF) + RT/αnFlnV.

The electron transfer number for BPA oxidation was calculated from the above equation, and from this constant value, the electron number n was calculated to be about 2. This means that in the Fe ₃ O ₄ -PEI composite, two electrons are involved in the electrooxidation of BPA.

2.6 Analytical Procedure

The relationship between BPA concentration and peak current was monitored using cyclic voltammetry under optimal experimental conditions. Each BPA concentration ranged from 0.01 μM to 10 μM in PBS solution (pH 6.8), and was detected at 100 mVs ^-1 _{injection rate using Fe 3} O _{4 -PEI.} 8A shows that the oxidation peak current increases linearly with BPA concentration. _{The linear plot is plotted in Figure 8B for a Fe 3} O ₄ -PEI/C modified electrode with a linear regression equation I(pa) = 1.645488 X + 2.62086 (R ² = 0.99524), with a low detection limit of 0.05 nM (S/N). = 3) was observed. Therefore, Fe ₃ O ₄ -PEI nanocomposite is an effective electrode material for sensitive detection of BAP. ^{In addition, interference studies were performed with 500-fold higher concentrations of K +} , Cl ⁻ , Ca ⁺ and 2-nitrophenol, 4-nitrophenol, 2,4 in 0.1 M PBS buffer (pH = 6.8) containing 10 μm BPA. - To understand the selectivity of the _{Fe 3} O ₄ -PEI/C electrode with a 50-fold higher concentration of dinitrophenol.

8C shows no particular change in the BPA peak current in the presence of inorganic salts and organic substances. This shows that the surface-customized Fe ₃ O ₄ -PEI nanocomposite has high selectivity and sensitivity in the detection of BPA, which is important for practical field applications. It may be a promising material for BPA detection. In addition, the Fe ₃ O ₄ -PEI nanocomposite electrode showed high catalytic activity in other phenolic compounds (2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol). Figure 8C shows the BPA peak at 0.574 V and the 2,4-dinitrophenol peak at 0.96 V, which indicates that the proposed Fe ₃ O ₄ -PEI/C electrode simultaneously detects BPA and other phenolic compounds in the real sample. confirm that it is suitable for

2.7 Fe ₃ O ₄ -Stability of PEI

By analyzing the repeatability of the BPA sensing study, we tried to evaluate the consistency of the _{Fe 3} O _{4 -PEI nanocomposite electrode several times using 10 μM BAP in 0.1M PBS buffer.} 8D shows the stability and reproducibility of _{the prepared Fe 3} O ₄ -PEI nanocomposite electrode stored at room temperature (22 C +- 2° C.) for more than 2 weeks. The stable BPA current shows good stability over 3 weeks, which exceeds many previously reported BPA sensors.

2.8 Real Sample Analysis

The fabricated Fe ₃ O ₄ -PEI nanocomposite electrode was applied to actual samples such as milk and tap water under optimal conditions. The known concentrations of the BPA-treated samples were analyzed by cyclic voltammetry and the results were compared with the GC-MS technique. Table 1 shows different amounts of BPA in actual samples (milk, tap water) with a recovery rate of 100.9% to 100.5%, and the Fe ₃ O ₄ -PEI nanocomposite electrode showed a high sensitivity correlation with GC-MS. This shows that the fabricated Fe ₃ O ₄ -PEI nanocomposite electrode is suitable for detecting BPA in real samples. In addition, the GC-MS results are described in FIG. 9 . Figure 9A shows the MS pattern at each BPA concentration of the real sample, the BPA mass peak was observed at RT 26.9 and correlated well with the standard BPA sample. The BPA concentration was derived from the standard BPA calibration plot (Fig. SI 3.). 9B _{shows a comparison of BPA sensitivity according to the Fe 3} O ₄ -PEI nanocomposite electrode and the GC-MS technique, and the proposed Fe ₃ O ₄ -PEI nanocomposite electrode shows a good correlation with the GC-MS technique. indicates visible. The mass patterns of standard BPA (0.1 mM) and real sample (0.01 mM BPA) both showed good correlation in FIGS. 9C and 9D. GC-MS results confirmed that the proposed Fe ₃ O ₄ -PEI nanocomposite electrode has high sensitivity to BPA in real samples. Table 1 below shows the BPA crystals (milk, tap water) in each real sample.

Sample BPA concentration (μM)

milk Addition (μM) Detection (μM) Detection by GCMS (μM) Recovery (%) Average recovery (%) One
3
5
10 1.01
3.02
4.99
10.09 0.99
3.05
4.95
10.1 101
100.6
99.8
100.9

100.9

tap water 2
4
6
8 2.02
4.01
6.01
8.03 1.99
3.99
5.99
8.01 101
100.2
100.1
100.9

100.5

(conclusion)

A novel low-cost sensing material based on Fe ₃ O ₄ -PEI nanocomposite has been successfully synthesized for high-sensitivity detection of BPA in real environmental samples. Characteristic results (XRD, XPS, FE-SEM, FTIR, zeta potential) confirmed that several positively charged species were present on the composite surface. The electrochemical results revealed that the fabricated Fe ₃ O ₄ -PEI nanocomposite showed high sensitivity, good stability, high conductivity, and good reproducibility in BPA detection. Fe ₃ O ₄ -PEI/sensor showed a wide linear sensitivity range of 0.01 μM to 50 μM and showed a low limit of detection of BPA of 0.05 nM without interaction with other compounds. BPA sensing in milk and tap water samples showed high response and correlation with GC-MS technique. In addition, the Fe ₃ O ₄ -PEI nanocomposite electrode showed high catalytic activity in other phenol compounds (2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol). The proposed low-cost Fe ₃ O ₄ -PEI/C sensor electrode can be a convenient electrochemical tool for the simultaneous detection of BPA and other phenolic compounds in food and real samples.

The scope of the present application is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present application. do.

Claims (5)

A first step of preparing Fe ₃ O _{4 nanoparticles by hydrothermal method;}
a second step of dispersing the Fe ₃ O ₄ nanoparticles prepared in the first step in water;
a third step of adding polyethyleneimine (PEI) to the mixture of the second step;
a fourth step of stirring the mixture mixed in the third step and sonicating for 5 to 15 minutes;
a fifth step of vibrating the sonicated mixture for 1 hour to 3 hours;
a sixth step of obtaining a magnetic composite material through magnetic treatment on the mixture of the fifth step;
a seventh step of washing the magnetic composite material obtained in the sixth step 3 to 5 times with ultrapure water to remove polyethyleneimine (PEI) not bound _{to Fe 3} O _{4 nanoparticles;} and
An eighth step of vacuum-drying the magnetic composite material of the seventh step at 50° C. to 70° C.; Fe ₃ O ₄ -PEI nanocomposite method for detecting bisphenol A, comprising: a. The method according to claim 1,
The first step of preparing the Fe ₃ O _{4 nanoparticles by hydrothermal method is Fe 3} for detecting bisphenol A, characterized in that a mixture _{of FeCl 2} ·4H ₂ O and FeCl ₃ ·6H _{2 O is used as an iron precursor.} O ₄ -PEI Nanocomposite material manufacturing method. The method according to claim 1,
The Fe ₃ O ₄ -PEI nanocomposite has diffraction peaks of (111), (220), (311), (400), (511), (440) and (533) crystallization planes,
In addition _{, the spectrum by FTIR of the Fe 3} O ₄ -PEI nanocomposite showed peaks at 1263 cm ^-1 , 1654 cm ^-1 , 2849 cm ^-1 , 2946.8 cm ^-1 and 3367.3 cm ^-1 with aliphatic NH stretching vibrations. Have,
Also, the Fe ₃ O ₄ -PEI nanocomposite material has a surface charge value of 30 mV to 40 mV. Method for producing _{Fe 3} O _{4 -PEI nanocomposite material for detecting bisphenol A.} A first step of preparing Fe ₃ O _{4 nanoparticles by hydrothermal method;}
a second step of dispersing the Fe ₃ O ₄ nanoparticles prepared in the first step in water;
a third step of adding polyethyleneimine (PEI) to the mixture of the second step;
a fourth step of stirring the mixture mixed in the third step and sonicating for 5 to 15 minutes;
a fifth step of vibrating the sonicated mixture for 1 hour to 3 hours;
a sixth step of obtaining a magnetic composite material through magnetic treatment on the mixture of the fifth step;
a seventh step of washing the magnetic composite material obtained in the sixth step 3 to 5 times with ultrapure water to remove polyethyleneimine (PEI) not bound _{to Fe 3} O _{4 nanoparticles;}
an eighth step of vacuum drying the magnetic composite material of the seventh step at 50°C to 70°C;
_{Fe 3} O ₄ -PEI nanocomposite prepared by the eighth step in ultrapure water as a solvent is mixed at a ratio of 1 mg/mL to 5 mg/mL (Fe ₃ O ₄ -PEI nanocomposite)/(ultra-pure water) to Fe A ninth step of preparing a ₃ O _{4 -PEI nanocomposite suspension;}
A 10th step of drop-casting the _{Fe 3} O ₄ -PEI nanocomposite suspension prepared by the ninth step on the cleaned electrode; and
_{An 11th step of evaporating the drop-casted Fe 3} O ₄ -PEI nanocomposite suspension in the 10th step in the atmosphere for 1 to 3 hours as a solvent, ultrapure water Fe _{3 for detecting bisphenol A comprising a;} O ₄ -PEI nanocomposite material sensor electrode manufacturing method. A first step of preparing Fe ₃ O _{4 nanoparticles by hydrothermal method;}
a second step of dispersing the Fe ₃ O ₄ nanoparticles prepared in the first step in water;
a third step of adding polyethyleneimine (PEI) to the mixture of the second step;
a fourth step of stirring the mixture mixed in the third step and sonicating for 5 to 15 minutes;
a fifth step of vibrating the sonicated mixture for 1 hour to 3 hours;
a sixth step of obtaining a magnetic composite material through magnetic treatment on the mixture of the fifth step;
a seventh step of washing the magnetic composite material obtained in the sixth step 3 to 5 times with ultrapure water to remove polyethyleneimine (PEI) not bound _{to Fe 3} O _{4 nanoparticles;}
an eighth step of vacuum drying the magnetic composite material of the seventh step at 50°C to 70°C;
_{Fe 3} O ₄ -PEI nanocomposite prepared by the eighth step in ultrapure water as a solvent is mixed at a ratio of 1 mg/mL to 5 mg/mL (Fe ₃ O ₄ -PEI nanocomposite)/(ultra-pure water) to Fe A ninth step of preparing a ₃ O _{4 -PEI nanocomposite suspension;}
A 10th step of drop-casting the _{Fe 3} O ₄ -PEI nanocomposite suspension prepared by the ninth step on the cleaned electrode;
_{An 11th step of evaporating the drop-casted Fe 3} O ₄ -PEI nanocomposite suspension in the 10th step in the atmosphere for 1 to 3 hours as a solvent; and
A buffer solution having a pH in the range of 6 to 7 is injected into a solution containing bisphenol A, and the solution containing bisphenol A and the buffer is brought into contact _{with the Fe 3} O _{4 -PEI nanocomposite in which the solvent is evaporated in the 11th step.} and a twelfth step of detecting bisphenol A using a cyclic voltammetry method; Fe ₃ O ₄ -Bisphenol A detection method using a PEI nanocomposite sensor electrode comprising:

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