CN101817091A - Method for preparing iron nano-magnetic particles by taking T4 phage as template - Google Patents

Abstract

The invention discloses a method for preparing iron nanometer magnetic particles using T4 bacteriophage as a template in the field of magnetic recording materials. This method utilizes the inherent structural characteristics of organisms and its molecular recognition function, and the enriched T4 phage and iron chloride solution are co-incubated, centrifuged, and reduced to obtain small particle size, high dispersion, and T4 phage. Iron nanoparticles are regularly arranged on the surface of the phage capsid, and the prepared iron nanoparticles have the characteristics of irreversible magnetization process and high coercive force, which makes the iron nanoparticles prepared by this method have great potential in the field of high-density magnetic recording materials. Broad application prospects. Moreover, the method directly uses biological nanostructures existing in nature as templates, the preparation process is simple, the reaction conditions are mild and environmentally friendly, and because the biological templates have the characteristics of self-reproduction and high shape repeatability, it is easy to realize large-scale production.

Description

A method for preparing iron nano-magnetic particles using T4 bacteriophage as a template

technical field

The invention belongs to the field of magnetic recording materials, and in particular relates to a method for preparing iron nanoparticles with small diameter and ferromagnetism by using T4 bacteriophage as a template.

Background technique

Transition metal iron (Fe) nanoparticles have the characteristics of small size, single magnetic domain structure, and high coercive force. The magnetic recording materials made with it have the advantages of good stability, clear image, high signal-to-noise ratio, and low distortion. It is because of these that nano-magnetic materials have broad application prospects in the field of high-density magnetic recording materials. However, with the development of information technology, the amount of information that needs to be recorded is also increasing. Therefore, the requirements for magnetic recording materials are getting higher and higher, and the high performance of recording materials is required, especially the high recording density. And as the magnetic recording unit of nano-magnetic particles, its size must meet the following requirements: ① the length of the particle should be much smaller than the recording wavelength; ② the width of the particle (including the length, if possible) should be much smaller than the recording depth; ③ a There should be as many magnetic particles as possible in a unit of recording volume. To sum up, nanoparticles as magnetic recording materials should meet the requirements of being as small as possible while still maintaining ferromagnetism. Therefore, exploring a preparation method capable of preparing small-sized and ferromagnetic Fe nanoparticles has become a research hotspot, and has also become the focus of competition in the information industry. In recent years, different methods have been used to prepare Fe nanomagnetic particles, the most commonly used is the pyrolysis of organometallic compounds. In this method, an organometallic compound is selected as a precursor, and is thermally degraded at a high temperature (usually in the range of 180-300° C.) to obtain metal nanoparticles. For example, articles published by Sheng Peng et al. in "JACS" (JACS, 2006, 128, 10676-10677) and Dorothy Farrell et al. in "Physical Chemistry" (J.Phys.Chem.B, 2005, 109, 13409-13419 Both have reported that Fe(CO) ₅ , an organic compound of iron, was used as a precursor to prepare Fe nanoparticles by thermal degradation. The particle size of the product is small and the particle distance is well controlled. However, most of the raw materials used in this method are toxic organic solvents, and the synthesis conditions require a high temperature environment, so it is an environmentally unfriendly synthesis route. People also use iron oleate as a precursor to obtain Fe nanoparticles through thermal degradation, but the prepared particles have irregular morphology, relatively large particle size, and do not have ferromagnetic properties, which limits the magnetic properties of Fe nanoparticles. Applications in the field of documented materials.

Contents of the invention

In order to overcome the shortcomings of conventional preparation methods, the present invention provides a method for preparing Fe nano magnetic particles using T4 phage as a template. The preparation process of this method is simple and the yield is high. The prepared Fe nanoparticles have the advantages of small particle size, regular arrangement on the surface of T4 bacteriophage, and high dispersion. At the same time, the prepared Fe nanoparticles have irreversible magnetization process and magnetic hysteresis. , High coercive force and other ferromagnetic characteristics, therefore, the obtained product meets the requirements of high-density magnetic recording materials. Moreover, the method directly uses biological nanostructures existing in nature as templates, has a wide range of sources of raw materials, and is easy to cultivate, thereby greatly reducing production costs. The raw materials used are also non-toxic, and are an environmentally friendly preparation method.

The present invention uses a highly symmetrical nano-scale organism as a template, utilizes its own structural characteristics, and the high molecular recognition ability of its surface protein, and according to the principle that transition metal cations and amino acid carboxyl anions have intermolecular forces, on its surface Controlling the growth of nanoparticles, due to the spatial confinement and structural characteristics of organisms, can effectively and accurately control the synthesis of nanoparticles, so as to obtain monodisperse Fe nanomagnetic particles of expected size.

In order to obtain Fe nanoparticles with small particle size and ferromagnetism, the present invention uses natural T4 phage as a template to control the synthesis of Fe nanoparticles on its surface. T4 bacteriophage is a potent phage that infects Escherichia coli and uses Escherichia coli as the host cell, which is very convenient for cultivation. Escherichia coli is the most important and most abundant bacterium in the intestinal tract of humans and many animals, and generally does not cause disease. Therefore, T4 bacteriophage is used as a template, which has the advantages of wide material sources and high reproducibility. The T4 bacteriophage used in the present invention has an icosahedral symmetrical structure, the capsid length is about 60nm, and the transverse diameter is about 50nm. Because it contains a variety of amino acids on its surface, many binding sites are provided for controlling the synthesis of Fe nanoparticles on its surface, and specific The binding sites are distributed regularly and repeatedly, so the prepared nanoparticles have good dispersion. And because of the spatial confinement effect of the protruding protein on the surface, the size of the synthesized nanoparticles is controlled, so that the prepared nanoparticles are uniform in size and small in size. It can be seen that due to the structural characteristics of T4 bacteriophage itself, it is a good template for preparing Fe nano-magnetic particles.

The present invention first utilizes Escherichia coli to cultivate T4 bacteriophages, after several times of centrifugation, the pure T4 phages are enriched, and then co-incubated with Fe chloride solution, so that iron positive ions are adsorbed to the activity of protein amino acid carboxyl anions on the surface of T4 capsid site, and then through centrifugation and reduction treatment, Fe nanoparticles with regular arrangement, small particle size and ferromagnetism were formed on the surface of T4 phage capsid.

Technical scheme of the present invention comprises the steps:

(1) Amplification culture and purification of T4 phage

First, insert T4 bacteriophage strains into 50ml pre-cultivated Escherichia coli suspension with a concentration of 10-15mg/ml, and culture it on a shaking table at a speed of 100-150r/min for 8-15 hours at 37°C. Centrifuge the suspension containing Escherichia coli residual shells and T4 phage three times at 4-10°C at a speed of 4000-6000r/min for 15-20min each time to remove the precipitate and take the supernatant. Finally, ultracentrifuge the relatively pure T4 phage liquid at 4-10°C, 40,000-45,000 r/min for 2.5-3 hours, remove the supernatant, and disperse the T4 phage precipitates into 2ml of deionized water.

(2) Preparation of Fe nanomagnetic particles using T4 phage as a template

Take 300-500 ul of the enriched T4 phage liquid, adjust the pH value to 8.5-9.0 with 1 mol/l NaOH, and incubate on a shaker at 4-10°C and 60-110 r/min for 3-5 hours. Add 300-500 ul of FeCl ₃ solution with a concentration of 5-10 mM to the above pretreated T4 phage liquid, mix well, and incubate on a shaking table at 4-10°C, 60-110 r/min for 12-20 hours. Then ultracentrifuge at 4-10° C., 40000-45000 r/min for 2.5-3 hours, remove the supernatant, collect and disperse the precipitate into 300-500 ul of deionized water. Then add 75-120ul freshly prepared NaBH ₄ reducing agent solution with a concentration of 5-10mM dropwise to obtain ferromagnetic Fe nanoparticles regularly arranged on the surface of the T4 phage capsid.

The Fe nano-magnetic particles have the following structural features: uniformly distributed on the outer surface of the T4 phage capsid, regularly arranged, highly dispersed, and small in size, with a size of 1.5-4.0nm.

The beneficial effects of the present invention are: the natural T4 phage is directly used as a template, the cultivation is simple and convenient, and no special treatment is required before the experiment. After co-incubation with iron chloride solution, and then centrifugation and reduction treatment, regular excretion can be obtained. Fe nanoparticles with small particle size and ferromagnetism distributed on the surface of T4 phage capsid. Compared with conventional Fe nanoparticles prepared by thermal degradation of precursors using iron organic compounds, the Fe nanoparticles obtained by the present invention have the advantages of more uniform distribution and smaller particle size. Very good ferromagnetism, which meets the requirements of magnetic recording materials for nano-magnetic particles. The preparation method has the advantages of simple process, mild conditions, environmental protection and high efficiency, wide and easy-to-obtain template sources, low cost, and easy realization of large-scale production.

Description of drawings

The present invention will be further elaborated below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is the low magnification TEM figure of the Fe nano-magnetic particle prepared with T4 phage as a template;

Fig. 2 is the high magnification TEM figure of the Fe nano-magnetic particles prepared with T4 phage as a template;

Fig. 3 is the EDS figure of the Fe nano-magnetic particle prepared with T4 bacteriophage as template;

Fig. 4 is a hysteresis loop curve of Fe nano magnetic particles prepared with T4 phage as a template.

Detailed ways

Embodiment one

1. Amplification and purification of T4 phage

First, insert T4 bacteriophage strains into 50ml of pre-incubated Escherichia coli suspension with a concentration of 10mg/ml, and culture at 37°C on a shaking table at a speed of 100r/min for 8h. Centrifuge the suspension containing Escherichia coli residual shell and T4 phage at 4°C at speeds of 4,000, 5,000, and 6,000 r/min, respectively, for 15 minutes each time, remove the precipitate, and take the supernatant. Finally, ultracentrifuge the pure T4 phage liquid at 4°C, 45000r/min for 2.5h, remove the supernatant, and disperse the T4 phage pellets into 2ml of deionized water.

2. Preparation of Fe nanomagnetic particles using T4 phage as template

Take 300 ul of the enriched T4 phage liquid, adjust the pH value to 8.5 with 1 mol/l NaOH, and incubate on a shaking table at 4°C and 60 r/min for 3 hours. Take 300 ul of FeCl ₃ solution with a concentration of 5 mM and add it to the above pretreated T4 phage liquid, mix well, and incubate at 4° C., 60 r/min on a shaking table for 20 h. Then at 4°C, ultracentrifuge at 45000r/min for 2.5h, remove the supernatant, collect and disperse the precipitate into 300ul of deionized water. Then, 75ul of newly prepared NaBH ₄ reducing agent solution with a concentration of 5mM was added dropwise to obtain ferromagnetic Fe nanoparticles regularly arranged on the surface of the T4 phage capsid. Its transmission electron microscope picture is shown in Figure 1.

Embodiment two

1. Amplification and purification of T4 phage

First, insert T4 phage strains into 50 ml of pre-incubated Escherichia coli suspension with a concentration of 12 mg/ml, and culture at 37° C. on a shaking table at a speed of 130 r/min for 12 hours. Centrifuge the suspension containing Escherichia coli residual shell and T4 phage at 10°C at speeds of 4,000, 5,000, and 6,000 r/min, respectively, for 17 minutes each time, remove the precipitate, and take the supernatant. Finally, ultracentrifuge the pure T4 phage liquid at 10°C, 42100r/min for 3h, remove the supernatant, and disperse the T4 phage pellets into 2ml of deionized water.

2. Preparation of Fe nanomagnetic particles using T4 phage as template

Take 400 ul of the enriched T4 phage liquid, adjust the pH value to 8.5 with 1 mol/l NaOH, and incubate at 10°C and 90 r/min on a shaking table for 4 hours. Take 400ul of FeCl ₃ solution with a concentration of 10mM and add it to the above-mentioned pretreated T4 phage solution, mix well, and incubate on a shaking table at 10°C and 90r/min for 12h. Then, ultracentrifuge at 10°C and 42100r/min for 3h, remove the supernatant, and collect and disperse the precipitate into 400ul of deionized water. Then, 120ul of newly prepared NaBH ₄ reducing agent solution with a concentration of 6mM was added dropwise to obtain ferromagnetic Fe nanoparticles regularly arranged on the surface of T4 phage capsid. The morphology observed under the transmission electron microscope is shown in Figure 2.

Embodiment three

1. Amplification and purification of T4 phage

First, insert T4 bacteriophage strains into 50 ml of pre-incubated Escherichia coli suspension with a concentration of 15 mg/ml, and culture at 37° C. on a shaking table at a speed of 150 r/min for 15 hours. Centrifuge the suspension containing Escherichia coli residual shell and T4 phage at 6°C at speeds of 4,000, 5,000, and 6,000 r/min, respectively, for 20 minutes each time, remove the precipitate, and take the supernatant. Finally, ultracentrifuge the pure T4 phage liquid at 6°C and 40,000 r/min for 3 hours, remove the supernatant, and disperse the T4 phage pellets into 2 ml of deionized water.

2. Preparation of Fe nanomagnetic particles using T4 phage as template

Take 500 ul of the enriched T4 phage liquid, adjust the pH value to 9.0 with 1 mol/l NaOH, and incubate at 6° C. for 5 h on a shaker at 110 r/min. Take 500 ul of FeCl ₃ solution with a concentration of 10 mM and add it to the above pretreated T4 phage liquid, mix well, and incubate at 6° C. on a shaking table at 110 r/min for 18 h. Then, ultracentrifuge at 6°C and 40000r/min for 3h, remove the supernatant, collect and disperse the precipitate into 500ul deionized water. Then, the newly prepared 90 ul NaBH ₄ reducing agent solution with a concentration of 10 mM was added dropwise to obtain ferromagnetic Fe nanoparticles regularly arranged on the surface of the T4 phage capsid.

Figures 1 and 2 are TEM images of Fe nanoparticles prepared with T4 phage as a template. It can be seen from the figure that the spherical gray shadow at the bottom is T4 phage, and a layer of Fe is evenly distributed on the outer surface of each phage capsid. Nanoparticles, small in size, 1.5-4.0nm in size, with regular particle distribution, proved that the preparation of Fe nanoparticles with T4 bacteriophage as a template is highly controllable in shape and size, and demonstrated the high efficiency of this method. sex.

Figure 3 is the EDS diagram of the preparation of Fe nanomagnetic particles using T4 phage as a template. The electron beam is shot on the combined structure of T4 phage and metal particles as shown in Figures 1 and 2. From the figure, it can be seen that Cu, C, The peaks of O and Fe, among which Cu and C mainly come from the copper mesh used in sample preparation. O mainly comes from T4 phage itself, and some O comes from water. In addition, we can see the existence of the energy spectrum peak of Fe from the figure, indicating that Fe nanoparticles were successfully prepared using T4 phage as a template.

Fig. 4 is a hysteresis loop curve of Fe nano-magnetic particles prepared with T4 phage as a template, and the detection temperature is 100K. It can be seen from the figure that the Fe nanoparticles prepared with T4 phage as a template have ferromagnetic properties such as irreversible magnetization process, easy magnetization to saturation, and hysteresis. Its coercivity is about 564Oe, remanence is about 34emu/g, and saturation magnetism is about 151emu/g. It shows that Fe nanoparticles prepared with T4 bacteriophage as a template have ferromagnetism, which makes it have broad application prospects in magnetic recording materials.

Claims (1)

1. take T4 phage as template to prepare the method for iron nano-magnetic particle, it is characterized in that, described method comprises the steps: (1) Amplification culture and purification of T4 phage First, insert T4 bacteriophage strains into 50ml of pre-cultivated Escherichia coli suspension with a concentration of 10-15mg/ml, and culture it on a shaking table at a speed of 100-150r/min at 37°C for 8-15h, and the E. Centrifuge the suspension of residual bacillus shell and T4 bacteriophage three times at 4-10°C at a speed of 4000-6000r/min, each time for 15-20min, remove the precipitate, take the supernatant, and finally put the purer T4 Ultracentrifuge the phage liquid at 4-10°C, 40,000-45,000 r/min for 2.5-3 hours, remove the supernatant, and disperse the T4 phage pellets into 2ml of deionized water; (2) Preparation of Fe nanomagnetic particles using T4 phage as a template Take 300-500ul of the enriched T4 phage liquid, adjust the pH value to 8.5-9.0 with 1mol/l NaOH, incubate on a shaker at 4-10°C, 60-110r/min for 3-5h, and take 300-500ul concentration Add 5-10mM FeCl ₃ solution into the above-mentioned pretreated T4 phage liquid, mix well, and incubate on a shaking table at 4-10°C, 60-110r/min for 12-20h, and then at 4-10°C, 40000- Ultracentrifuge at 45000r/min for 2.5~3h, remove the supernatant, collect and disperse the precipitate into 300~500ul deionized water, then add dropwise the newly prepared 75~120ul NaBH ₄ reducing agent solution with a concentration of 5~10mM , that is to obtain Fe nanoparticles regularly arranged on the surface of T4 bacteriophage capsid, small particle size and ferromagnetic.

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