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reusable nanosilver-coated magnetic particles for ultrasensitive sers-based detection of malachite green in water samples

by:Newland     2020-03-06
A new type of silver
Deposited silica-
Magnetic Particles (Fe3O4@SiO2@Ag)
A polymer with uniform size and good surface-enhanced Raman activity and magnetic response was synthesized with aminated polymer.
Fe4 @ si02 @ Ag magnetic particles have been successfully used for Peacock Green (MG)
In water samples
The mechanism is that MG can be adsorbed on the silver surface of nano silver.
By coating magnetic particles with a nitrogen atom, the nano-silver layer formed on magnetic particles significantly enhances the Raman signal strength of MG.
The developed sensing system showed a sensitive response to MG in the range of 10 fM to 100 μm, with a low detection limit (LOD)
2 fM under optimal conditions.
Several orders of magnitude lower than other methods. This SERS-
The sensor-based MG detection has good repeatability and stability. The silver-
Only when a low pH solution is used in multiple sensing events can coated magnetic particles be easily regenerated as surface-enhanced Raman substrates.
The recovery rate of adding MG to several water samples at different concentrations was between 90% and 110%.
This method is conducive to ultra-sensitive analysis of dyes to meet the high requirements of ensuring the safety of water sources.
Iron Chloride in six water (FeCl-6HO)
Silver nitrate (AgNO)
Sodium acetate, peacock green chloride (
Swiss products)
Ethylene glycol (MW 3400)
And poly (
Propylene hydrochloride)(PAH, MW 70u2009kDa)
Bought from Sigma.
Received Aldrich and use.
Ammonia solution (28. 0–30. 0u2009wt. %)
Obtained from sanchun pure chemical company.
Unless specifically stated, other chemicals are grade-1 and use highly pure water throughout the course of the experiment.
Reserve solution of MG (10u2009mol/L)
Prepared by dissolving a proper amount of peacock green chlorine in highly pure water.
Purchased from AIM magnet Co a range of strong nd rod magnets with a diameter of 3mmLtd.
Hot media and KQ-
250DB CNC ultrasonic cleaning machine was also used in the study.
FeO magnetic particles (400u2009nm)
First synthesis by an improved solvent thermal reaction. Typically, 1.
Under magnetic stirring, 35g FeCl · 6HO was dissolved in 40 ml ethylene glycol for 30 min.
Then, 2.
Add 7g of NaAc and 1g of PEG 6000 to this solution and stir until the reactants are completely dissolved.
The mixture is then transferred to Teflon
Lined autoclave (50u2009mL capacity)
And heat 200 °C for 12 h.
The product was collected with the help of the magnet and then washed three times with deionized water and ethanol respectively.
The final product is vacuum dried for 5 hours at 60 °c.
Prepare SiO @ FeO magnetic particles at 0. 1u2009g as-
The prepared FeO particles are dispersed in deionic water-ammonia-
Mixed solution of ethanol (5:4:5, v/v)
Through 15 minutes of ultrasonic treatment.
100 u2009 μ l four oxygen Silicon (TEOS)
It is slowly falling into the above solution by powerful ultrasonic treatment.
The mixture is kept at room temperature for 45 minutes.
The product is dried in a vacuum oven at 60 °c for 5 u2009 h and then washed with deionized water and ethanol.
The surface aminations of FeO @ SiO magnetic particles are self-made through a PAH
Assembly process under Ultrasonic Action. Typically, 0.
Month g PAH is Germanionized water (50u2009mL)
Ultrasound 10 min, 0. 1u2009g as-
The prepared FeO @ SiO particles were added again for 20 minutes under the action of ultrasonic wave.
Gradually self
Assemble on FeO @ SiO particles.
The FeO @ SiO @ PAH particles will then be obtained for magnetic separation and rinsed five times with deionized water.
Next, 3 ~ Gold at 5 nm-
As mentioned earlier, the seeds were synthesized through some modifications.
In short, the HAuCl of 20 ml (5u2009mM)
And 20 mL sodium citrate (5mM)
Was added to Jingdong ml de-
Ionize the water and stir violently.
After that, 10 ml freshprepared NaBH (0. 1u2009M)
After adding, the color of the solution changes from colorless to orange.
Then, the solution is stirred for 4 h at RT, and the diameter of the spherical gold particles is about 3 ~ 5 nm. PAH-
Mix the modified SiO @ FeO particles with Auntie to form FeO @ SiO @ PAH-
Auntie interacts through static electricity.
After ultrasonic treatment for 1 u2009 h, separate the mixture with a magnet and wash it three times with deionized water.
Get FeO @ SiO @ Ag, 10mg FeO @ SiO-
Au NPs is dispersed in 100 AgNO solution (0.
25mm, including 0. 2u2009wt% PVP).
37% formaldehyde exceeding the standard (150u2009μL)
And 25% ammonia solution (300u2009μL)
Add in order.
FeO @ SiO @ Ag magnetic particles were obtained within 2 min under 30 °c ultrasonic treatment.
Magnetic separation of the product, washed five times with deionized water to remove excess PVP.
For the quantitative analysis of MG concentration, standard MG solutions from 10 mol/L to 10 mol/L were prepared with MG Reserve solution.
For surface-enhanced Raman spectroscopy measurements, a 50 μ l MG solution of different concentrations is mixed with a 100 μ l FeO @ SiO @ Ag magnetic particle in the EP tube, which is heated at TMR1,200u2009rpm)
At room temperature for 30 minutes to prevent particle deposition.
The mixture is then separated with a magnet and the upper layer is removed.
With the help of an ultrasonic cleaner, clean the magnetic particles three times with pure water.
Then, add 10 μ l purified water to the EP tube and mix the magnetic particles thoroughly again.
Subsequently, the 2 μ l sample solution was drip onto the 50 nm gold film deposited on the glass plate.
After drying at room temperature, the surface-enhanced Raman spectra of MG adsorbed on magnetic particles were detected by Raman spectra.
In order to achieve ultra-sensitive detection of MG, experimental conditions such as laser power, exposure time and accumulation time were optimized.
In order to study the effect of the initial pH value on MG adsorption and detection, the initial pH value of the solution was adjusted to 2,3, 3. 5, 4, 4.
5 and 5 of hydrochloric acid were added.
In order to evaluate the potential matrix effects of environmental samples on MG detection, Spike samples from laboratory tap water, bottled water and secondary effluent (
Qinghe sewage treatment plant, Beijing, China)
The tests were conducted at concentrations of 1 μm, 10 nm, 100pm and 1 pm.
Co-focal Raman microscope in inVia (
Reinshaw, UK)
Excitation laser with 633nm, 50 × 1,200 long distance target and mm line/mm grating (
Please note that surface enhanced Raman spectrum signals with low MG concentration were obtained by repeating the accumulation five times).
Get pH measurements with pH meter (FE20-
FiveEasy from mettler toledo).
Obtain TEM images using Hitachi transmission electron microscopy (H-7650B, Japan).
Scanning electron microscope (SEM)
Capture images using S-
4800 scanning electron microscope (Hitachi, Japan).
Absorbance measurements were performed on Nanodrop 2000 (
Thermo Fisher, USA).
Hot media and KQ-
250DB CNC ultrasonic cleaning machine was also used in the experiment.
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