A method for the synthesis of porous silica colloidal spheres

Abstract

The application discloses a synthesis method of porous silica colloidal spheres, and relates to the technical field of biological medicines. The method comprises the following steps: 2,6-diaminopyridine is dissolved in a mixed solvent and dissolved by stirring; sodium hydroxide aqueous solution and ethylenediamine are added into the mixed solution, and tetraethyl orthosilicate and glyoxal are sequentially added into the mixed solution; the solution is transferred into a centrifugal tube, supernatant is poured away, the solid at the bottom of the centrifugal tube is reserved, and the solid is dispersed again by using ethanol; the obtained solid is dried in an oven, etching is carried out by using hydrofluoric acid, and porous silica colloidal spheres are obtained after centrifugal drying. In the application, a brand-new synthesis idea is designed by copolymerization of 2,6-diaminopyridine, ethylenediamine, glyoxal and tetraethyl orthosilicate, and by coating of an alkaline polymer, controllable etching of silicon is realized, and uniform porous silica colloidal spheres and silica colloidal spheres with a loose porous eggshell structure and a compact solid yolk structure are obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biological medicine, and particularly relates to a synthesis method of porous silica colloidal spheres. BACKGROUND

[0002] Porous materials are the focus of research in many fields such as catalysis, adsorption, separation, chromatography, chemical sensors and biological sciences. Monodisperse colloidal porous silica nanoparticles have greater potential in the above applications due to their nanoscale size, especially in various nanotechnology applications including biomedical and biotechnology. In recent years, researchers have devoted to developing nanoparticles with complex porous structures for major research work in different fields. Their nanoscale size, high surface area and large porosity make ordered mesoporous nanoparticles useful for adsorption, catalysis, energy storage, controlled drug release and cell delivery. The composition and structure of nanoparticles are the key to realizing performance.

[0003] For many years, researchers have made many successful porous silica nanospheres, but most of the production of these nanospheres relies on soft templates composed of surfactants or hard templates composed of other colloidal crystals. The size, mesostructure and morphology of the obtained silica nanospheres are limited by these templates, and it usually involves quite complex preparation steps and high cost to remove these templates to obtain the target structure.

[0004] The conventional synthesis method of silica generally obtains uniform silica colloidal spheres or porous silica colloidal spheres. The classical structure can only have the size of the spheres and the pore structure as the adjustable variables, which may not be able to meet the needs in various applications, such as in the field of biological medicine and environmental protection. Under such a background, the yolk-porous shell structure of the silica colloidal spheres adds a new adjustable variable, i.e. the ratio between the yolk and the shell, to the traditional silica spheres. Moreover, the loose and porous shell on the outer surface has excellent performance in adsorption and carrying, and can be used as a drug carrier to provide better drug release control. This new structure is likely to have various applications in the fields of medicine, environmental protection, optics, electronics and catalysis. In addition, since the silica colloidal spheres are environmentally friendly and biodegradable, they are more likely to play an important role in environmental protection and biological medicine. SUMMARY

[0005] The present application aims to provide a synthesis method of porous silica colloidal spheres to solve the problems in the background art.

[0006] To achieve the above object, the present application provides the following technical scheme.

[0007] A method for synthesizing porous silica colloidal spheres, comprising the following steps: step S100: dissolving 2, 6-diaminopyridine in a mixed solvent and dissolving by stirring to obtain a yellow transparent solution; step S200: adding an aqueous sodium hydroxide solution and ethylenediamine into the mixed solution of step S100 and stirring for half an hour; step S300: adding tetraethyl orthosilicate into the mixed solution of step S200 and continuously stirring until the solution becomes white; step S400: adding glyoxal into the mixed solution of step S300 and continuously stirring until the color of the solution gradually changes from white to brownish yellow; step S500: transferring the solution obtained in step S400 into a centrifugal tube, discarding the supernatant, retaining the solid at the bottom of the centrifugal tube, and dispersing the solid with ethanol again; step S600: repeating step S500 three times, and drying the solid obtained in the last time in an oven overnight to obtain polymer-coated silica colloidal spheres; and step S700: etching the product obtained in step S600 with hydrofluoric acid under the condition of no stirring, and drying by centrifugation to obtain porous silica colloidal spheres.

[0008] Based on the above technical solution, the application further provides the following optional technical solutions.

[0009] In an optional solution, the mixed solvent in step S100 is a mixed solution of ethanol and water with a volume ratio of 2:1.

[0010] In an optional solution, the concentration of the aqueous sodium hydroxide solution in step S200 is 2 mol / L and the amount used is 0.72 mL.

[0011] In an optional solution, the amount of 2, 6-diaminopyridine used is 0.3 g, the amount of glyoxal used is 0.95 mL, and the amount of ethylenediamine used is 0.6 mL.

[0012] In an optional solution, the amount of tetraethyl orthosilicate used is 2.4-9.6 mL.

[0013] In an optional solution, in step S500, the centrifugal tube is centrifuged at a speed of 7000 revolutions per minute for 5 minutes.

[0014] In an optional solution, in step S700, the mass concentration of the hydrofluoric acid is 10%.

[0015] Compared with the prior art, the application has the following beneficial effects:

[0016] In the present application, a brand new synthetic idea is designed by co-polymerization of 2,6-diaminopyridine, ethylenediamine and glyoxal and tetraethyl orthosilicate, and a controllable etching of silicon is realized by coating of alkaline polymer. Specifically, hydrofluoric acid will react with alkaline polymer, and at the same time of consuming the outer alkaline polymer, the reactivity of hydrofluoric acid to silicon dioxide becomes controllable, resulting in a partial selective etching of silicon dioxide spheres instead of complete etching. In this method of selective etching of silicon dioxide spheres by hydrofluoric acid under the protection of alkaline polymer coating, by changing the amount of tetraethyl orthosilicate, a uniform porous silica colloidal sphere and a novel silica colloidal sphere with a loose porous eggshell and a compact solid yolk structure can be obtained. In summary, the present application expands the synthetic idea of silicon nanomaterials, and successfully prepares two different porous silica colloidal spheres. This controllable and adjustable porous colloidal sphere is likely to be a brand new carrier material in the field of biological medicine. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Scanning electron microscope image of the porous silica colloidal sphere prepared for Example One of the present application.

[0018] Figure 2 Transmission electron microscope images of the uniform porous silica colloidal spheres prepared in the present application with different amounts of tetraethyl orthosilicate (a) 2.4 mL, (b) 3.0 mL.

[0019] Figure 3 Transmission electron microscope images of the porous egg yolk-eggshell structure silica colloidal spheres prepared in Example Three of the present application with different amounts of tetraethyl orthosilicate (a) 3.6 mL, (b) 4.8 mL, (c) 6.0 mL, (d) 9.6 mL.

[0020] Figure 4 Schematic diagram of the reaction mechanism and experimental idea of the present application. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below with reference to the examples. The examples listed in the present application are only used to illustrate the present application, and are not used to limit the scope of the present application. Any obvious modification or change made to the present application does not deviate from the spirit and scope of the present application.

[0022] In the present application, a brand new synthetic idea is designed by co-polymerization of 2,6-diaminopyridine, ethylenediamine and glyoxal and tetraethyl orthosilicate, and a controllable etching of silicon is realized by coating of alkaline polymer, resulting in a uniform porous silica colloidal sphere and a silica colloidal sphere with a loose porous eggshell and a compact solid yolk structure. The reaction mechanism and experimental idea are as shown in Figure 4 .

[0023] The embodiment of the present application provides a synthesis method of porous silica colloidal spheres, which comprises the following steps:

[0024] Step S100: dissolving 2, 6-diaminopyridine in a mixed solvent and dissolving by stirring to obtain a yellow transparent solution;

[0025] Step S200: adding a sodium hydroxide aqueous solution and ethylenediamine into the mixed solution of step S100 and stirring for half an hour;

[0026] Step S300: adding tetraethyl orthosilicate into the mixed solution of step S200 and continuously stirring until the solution becomes white;

[0027] Step S400: adding glyoxal into the mixed solution of step S300, and continuously stirring until the color of the solution gradually changes from white to brown yellow;

[0028] Step S500: transferring the solution obtained in step S400 into a centrifugal tube, pouring away the supernatant, retaining the solid at the bottom of the centrifugal tube, and dispersing the solid with ethanol again;

[0029] Step S600: repeating step S500 three times, and drying the solid obtained in the last time in an oven overnight to obtain silica colloidal spheres coated with polymers;

[0030] Step S700: etching the product obtained in step S600 by using hydrofluoric acid under the condition of no stirring, and drying by centrifugation to obtain porous silica colloidal spheres;

[0031] The following embodiments are implemented on the premise of the technical scheme of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments. Example 1

[0032] 0.3 g of 2, 6-diaminopyridine was dissolved in a mixed solvent of 50 mL of ethanol and 25 mL of water by stirring for one hour, so that it was completely dissolved to obtain a yellow transparent solution.

[0033] 0.72 mL of a sodium hydroxide solution (2 mol / L) and 0.6 mL of anhydrous ethylenediamine solution were added into the mixed solution, and stirred for half an hour.

[0034] 2.4 mL of tetraethyl orthosilicate was added into the mixed solution, and continuously stirred until the solution became white.

[0035] 0.95 mL of glyoxal was added to the mixed solution, and the solution color gradually changed from white to brownish yellow with constant stirring. The resulting solution was transferred to a centrifuge tube and centrifuged at 7000 rpm for 5 minutes, the supernatant was poured out, the solid at the bottom of the centrifuge tube was retained, and was dispersed again with ethanol, which was repeated three times, and the solid obtained in the last time was placed in an oven to dry overnight, to obtain the polymer-coated silica colloidal spheres.

[0036] The product obtained in the previous step was etched with 10% mass concentration of hydrofluoric acid without stirring, and the uniform porous silica colloidal spheres were obtained by centrifugal drying.

[0037] The scanning electron microscope image of the sample product prepared in this example is shown in Figure 1 . Example Two

[0038] 0.3 g of 2,6-diaminopyridine was dissolved in a mixed solvent of 50 mL of ethanol and 25 mL of water by stirring for one hour, to obtain a yellow transparent solution.

[0039] 0.72 mL of sodium hydroxide solution (2 mol / L) and 0.6 mL of anhydrous ethylenediamine solution were added to the mixed solution, and stirred for half an hour.

[0040] 3.0 mL of tetraethyl orthosilicate was added to the mixed solution, and the solution was stirred until it became white.

[0041] 0.95 mL of glyoxal was added to the mixed solution, and the solution color gradually changed from white to brownish yellow with constant stirring. The resulting solution was transferred to a centrifuge tube and centrifuged at 7000 rpm for 5 minutes, the supernatant was poured out, the solid at the bottom of the centrifuge tube was retained, and was dispersed again with ethanol, which was repeated three times, and the solid obtained in the last time was placed in an oven to dry overnight, to obtain the polymer-coated silica colloidal spheres.

[0042] The product obtained in the previous step was etched with 10% mass concentration of hydrofluoric acid without stirring, and the uniform porous silica colloidal spheres were obtained by centrifugal drying.

[0043] Please refer to Figure 2 , Figure 2 a is the transmission electron microscope image of the uniform porous silica colloidal spheres prepared in Example One; Figure 2 b is the transmission electron microscope image of the uniform porous silica colloidal spheres prepared in this example; wherein, with the increase of the amount of tetraethyl orthosilicate, the size of the uniform porous silica colloidal spheres is increased to about 550 nm. Example Three

[0044] Compared with Example 1, the difference in the synthesis method of porous silica spheres in this example is that the amount of tetraethyl orthosilicate used is adjusted to 3.6 mL, 4.8 mL, 6.0 mL, and 9.6 mL respectively; Figure 3 As shown in the transmission electron microscope (TEM) image of the uniform porous silica spheres prepared in this embodiment, with the increase of tetraethyl orthosilicate (TES), a solid silicon core gradually forms inside the uniform porous silica. It is noteworthy that once this solid silicon core appears, even with further increases in the amount of TES, the diameter of the core remains essentially unchanged at approximately 550 nm, but the thickness of the loose porous silica shell increases accordingly, from a diameter of 100 nm (…). Figure 3 a) Initially, it could eventually reach 335 nm ( Figure 3 d).

[0045] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A method for the synthesis of porous silica colloidal spheres, characterized in that, The method comprises the following steps: Step S100: dissolving 2, 6-diaminopyridine in a mixed solvent and dissolving by stirring to obtain a yellow transparent solution; the mixed solvent is a mixed solution of ethanol and water in a volume ratio of 2:1; Step S200: adding an aqueous sodium hydroxide solution and ethylenediamine into the mixed solution of step S100 and stirring for half an hour; Step S300: adding tetraethyl orthosilicate into the mixed solution of step S200 and continuously stirring until the solution becomes white; Step S400: adding glyoxal into the mixed solution of step S300 and continuously stirring until the color of the solution gradually changes from white to brownish yellow; Step S500: transferring the solution obtained in step S400 into a centrifuge tube, pouring off the supernatant, retaining the solid at the bottom of the centrifuge tube, and dispersing the solid with ethanol again; Step S600: repeating step S500 three times, and drying the solid obtained in the last time in an oven overnight to obtain polymer-coated silica colloidal spheres; Step S700: etching the product obtained in step S600 with hydrofluoric acid under the condition of no stirring, and drying by centrifugation to obtain porous silica colloidal spheres. The concentration of the aqueous sodium hydroxide solution in step S200 is 2 mol / L, and the amount used is 0.72 mL.

2. The method of claim 1, wherein the porous silica colloidal spheres are synthesized by the process comprising: The amount of 2, 6-diaminopyridine used is 0.3 g, the amount of glyoxal used is 0.95 mL, and the amount of ethylenediamine used is 0.6 mL.

3. The method of claim 1, wherein the porous silica colloidal spheres are synthesized by the process comprising: The amount of tetraethyl orthosilicate used is 2.4-9.6 mL.

4. The method of claim 3, wherein the porous silica colloidal spheres are synthesized by the process comprising: In step S500, the centrifuge tube is centrifuged at a speed of 7000 revolutions per minute for 5 minutes.

5. The method of claim 1, wherein the porous silica colloidal spheres are synthesized by the process comprising: In step S700, the concentration of the hydrofluoric acid is 10%.

6. The method of claim 1, wherein the porous silica colloidal spheres are synthesized by the process comprising: ​

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