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Magnetic relaxation switch based on Fe3O4 at Au and preparation method thereof

A switching and magnetic technology, applied in the measurement of magnetic variables, magnetic resonance measurement, measurement of magnetic variables, etc., can solve the problem of insufficient concentration correlation, and achieve the effect of suitable size, low detection limit, and uniform particle size

Inactive Publication Date: 2010-10-20
FUDAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] MRSw technology is currently in its infancy, and despite the obvious practical prospects, the T of MRSw 2 The correlation between the signal change and the concentration of the analyte is not stable enough, and the T 2 The signal has completely different changing trends before and after the concentration of the analyte reaches the highest value of the detection range. It is necessary to use other detection methods to supplement and demonstrate the relaxation switch technology, and to improve the practical application value of MRSw in the way of multiple detection.

Method used

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  • Magnetic relaxation switch based on Fe3O4 at Au and preparation method thereof
  • Magnetic relaxation switch based on Fe3O4 at Au and preparation method thereof
  • Magnetic relaxation switch based on Fe3O4 at Au and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0029] Embodiment 1: the nanometer Fe of synthetic dextran wrapping 3 o 4

[0030] Add 4 mL of concentrated NH to 15 mL of dextran aqueous solution (15% w / w, Mw=20000) at room temperature 4 OH (>25% w / w) to make the pH of the solution about 11.7, and then heated to 25° C. in a water bath under magnetic stirring. Put 0.75gFeCl 3 ·6H 2 O and 0.28 g FeSO 4 4H 2O was dissolved in 5 mL of water, filtered through a 0.22 μm filter membrane and added dropwise to the dextran solution, the solution turned into a black turbid liquid, and stirred for 0.5 h. Afterwards, the turbid solution was centrifuged at 10,000 rpm for 20 minutes to remove larger particles, and the upper orange-red clear solution was dialyzed with deionized water for 24 hours (using a dialysis bag of 25 kDa) to remove excess ammonium ions and free dextran in the solution. Afterwards, the above solution was concentrated by centrifugal ultrafiltration. TEM images showing the resulting Fe 3 o 4 The nanoparticle ...

Embodiment 2

[0031] Embodiment 2: synthetic flower shape Fe 3 o 4 @Au magnetic nanoparticles

[0032] Take 5mL of the above concentrated Fe 3 o 4 Nanoparticle solution, add 4 mL of deionized water, add 200 μL of NH under magnetic stirring 2 OH (w / w=1%) aqueous solution, stirred for 10min, added 0.5g glucose as reducing agent, then added 50μL of NH 4 OH (7%), make the pH of the solution about 9.0, then add 100 μL of 0.25% HAuCl in 4 times 4 Aqueous solution, a total of 400μL was added, with an interval of 10min between each two, with HAuCl 4 The solution gradually changed from reddish brown to dark red. Afterwards, centrifuge at 7000rpm for 6min, remove the supernatant, and redissolve the lower sediment in water, and then undergo repeated ultrasonic dispersion (80W) and centrifugal separation and washing for 5 times to remove Fe that is not wrapped with Au. 3 o 4 , and finally dissolved in 1% dextran solution, the solution was dark blue and could remain stable within a week. The TE...

Embodiment 3

[0033] Example 3: In Fe 3 o 4 Surface modification of @Au magnetic nanoparticles with biotin

[0034] First self-assemble cystamine on the particle surface: take 2mL of the above Fe 3 o 4 @Au solution was centrifuged at 7000rpm for 6mins to remove the supernatant, and 2mL of 1mM PBS (pH=8.0) was added, and cystamine solution was added while sonicating to make the final concentration 4mM. Continue sonicating for 10min, then magnetically stirred for 8h, centrifuged again and used Washed three times with deionized water, and finally ultrasonically dispersed in 5 mL of 1 mM PBS (pH=8.0) solution, and 200 μL of 5% dextran solution was added to improve the stability of the solution.

[0035] Then connect Biotin through cystamine: Dissolve 2mg Biotin, 10mg EDC, 1mg NHS in 2mL 2mM PBS (pH=7.4) buffer, shake gently for 10mins, and then add to the above Fe 3 o 4 @Au solution, magnetically stirred for 12 hours and then centrifuged at 7000rpm for 6 minutes, removed the supernatant, w...

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Abstract

The invention belongs to the technical field of magnetic relaxation switch detection, in particular to a magnetic relaxation switch based on Fe3O4 at Au and a preparation method thereof. Probes adopted by the magnetic relaxation switch of the invention are flower-shaped magnetic nanometer particles with identification marks decorated on the surfaces, and the flower-shaped magnetic nanometer particles are in Fe3O4 at Au nuclear shell structures, the particle diameter of the probes is ranged from 50 to 70nm, and the relaxation degree R2 of the probes is 9.35 mM<-1>.s<-1>. Through decorating identification molecular biotin on gold layers of the nanometer particle surfaces, the invention realizes the fast, simple and convenient detection of the model protein Avidin, and the detection limit is as low as the level of 10 nM. The invention solves the problems of inconvenient implementation and unstable detection results of the existing magnetic relaxation switch technology.

Description

technical field [0001] The invention belongs to the technical field of magnetic relaxation switch detection, in particular to an Fe-based 3 o 4 Magnetic relaxation switch of @Au magnetic nanoparticles and its preparation method. Background technique [0002] The biosensor based on superparamagnetic nanoparticles is a high-efficiency detection technology developed in recent years. It breaks through the limitation of magnetic resonance in vitro application. This technology is called magnetic relaxation switch technology (Magnetic RelaxationSwitch). In an external magnetic field, the magnetic dipole of the paramagnetic particle itself will generate a small magnetic field disturbance around it, causing 1 H nuclear spin degenerates, such that detected by radio wave pulse train 1 The H signal will weaken, and the time constant determined by the obtained relaxation exponential degradation curve is T 2 , when the target molecule appears in the solution, the groups on the surface...

Claims

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Application Information

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IPC IPC(8): G01R33/50G01R33/465G01N21/33G01N33/68B22F1/02
Inventor 梁国海孔继烈
Owner FUDAN UNIV
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