CN103801269B - Preparation of a Surface Imprinted Graphene Composite - Google Patents

Abstract

The invention relates to the technical field of preparation of molecularly imprinted materials, in particular to a method for preparing a surface-imprinted graphene composite material with specific recognition, which is characterized in that firstly, graphene oxide is uniformly dispersed in a buffer solution, and the obtained graphene oxide Add dopamine hydrochloride and template molecules into the dispersion, stir, centrifuge and wash, and finally remove the template molecules by eluting to obtain a molecularly imprinted graphene composite material, wherein graphene is used as a carrier, and dopamine hydrochloride is a polymerized monomer. This method has mild reaction conditions, Green and environmentally friendly, high efficiency and low cost, the obtained molecularly imprinted graphene composite material has the characteristics of high binding capacity, rapid and specific recognition of template molecules.

Description

Preparation of a Surface Imprinted Graphene Composite

technical field

The invention relates to an organic-inorganic molecular imprinted composite material, especially a surface imprinted graphene composite material with specific recognition.

technical background

Molecularly imprinted polymers (MIPs) are synthetic artificial receptors that have cavities that match the shape of substrate molecules, and functional groups with specific arrangements that can recognize substrate molecules. Compared with conventional and Compared with traditional separation and analysis media, the outstanding feature of molecularly imprinted polymers based on molecular recognition is that they are highly selective for the separated substance or analyte. At the same time, molecularly imprinted polymers have good physical and chemical stability and can withstand high temperatures , high pressure, acid-base, organic solvent, etc., have three characteristics of predetermined structure and effect, specific recognition and wide practicability. Therefore, it has been increasingly widely used in chemical catalysis, material science, chromatographic separation, bionic sensing, etc. .

Methods for preparing molecularly imprinted polymers include bulk polymerization, suspension polymerization, precipitation polymerization, emulsion polymerization, and surface imprinting methods. In the early days, bulk polymerization was mostly used to prepare MIPs, that is, template molecules, functional monomers, and cross-linking agents were added to the solution. Polymerization produces porous, hard and bulky polymers, which are ground, crushed, and sieved to obtain molecularly imprinted polymers with a certain particle size, and finally eluted to remove template molecules. This method is simple and direct, but the polymers obtained by this method The particles are large, not uniform enough, and the imprinting efficiency is not high. Suspension polymerization and emulsion polymerization have a greater improvement than bulk polymerization, and can obtain polymers with larger surface area and uniform particles, and the imprinting effect is better than bulk polymerization. Higher. However, the polymers obtained by these methods, because the imprinted sites are still inside the polymer, the template molecules are not easy to elute, and the binding sites are less, so on this basis, the surface molecular imprinting technology has gradually developed. Imprinting is to use certain means to make the imprinted binding site stay on the surface of the imprinted polymer as much as possible, which can make the template molecule more accessible to the binding site, which is conducive to the elution and recombination of the template molecule. Macromolecules are especially suitable. Zhou et al. (ZhouW, JMaterChem., 2010, 880-883) used dopamine as a functional monomer and a cross-linking agent to self-polymerize dopamine under weakly alkaline conditions, on the surface of superparamagnetic ferric oxide Preparation of molecularly imprinted membrane of bovine hemoglobin. Experimental results show that polydopamine membrane has controllable thickness and small non-specific adsorption. It is a new type of molecularly imprinted material for protein preparation. Chen et al. (ChenT, JMaterChem., 2012, 3990-3996) A kind of imprinting material was synthesized by using silicon nanowires as the strengthening material of protein molecular imprinting, dopamine as the monomer, and bovine hemoglobin as the template molecule. The material reached the adsorption equilibrium within 5 minutes, and had specific recognition and strong Binding force. At the same time, through the study of stability and reproducibility, it is found that imprinted nanowires have significant reproducibility.

Graphene is a single-layer carbon atomic surface material stripped from graphite materials. It is a two-dimensional structure of carbon and a "super material". .The surface imprinting technology based on graphene has the following advantages: (1) molecularly imprinted polymers with controllable size and shape can be obtained through graphene; (2) graphene has good mechanical and thermal properties, so graphene As a matrix, it can also improve the mechanical properties and durability of MIPs; (3) graphene has a large specific surface area and a very small thickness. Compared with commonly used carrier materials, imprinting only occurs on the surface of graphene, which is beneficial to reduce The "embedding" phenomenon is also beneficial to the elution and recognition of template molecules, thus improving the utilization rate of template molecules.

Dopamine (DA) is a protein-mimicking small molecule. It is easy to polymerize to form a polydopamine (PDA) film under weak alkaline conditions. It can be spontaneously carried out at room temperature without adding an initiator, and the film thickness can be controlled. Stable and long-term durability under certain conditions. In addition, there are multifunctional groups such as amino groups and catechol groups on PDA, which have good hydrophilicity and biocompatibility, and are especially suitable for imprinting biologically active substances (ZhuoR, Chem .Commun., 2008, 5761-5763; ZhouW, JMaterChem., 2010, 880-883).

This patent combines the advantages of graphene and dopamine, using graphene as a carrier and dopamine hydrochloride as a functional monomer, to synthesize a surface-imprinted graphene composite material with specific recognition. The preparation method is simple, low in cost, and the reaction process is easy to control , can obtain good biocompatibility imprinting material, it not only has good selectivity, but also shows the advantages of high binding capacity and good reproducibility, so it has broad prospects in practical applications.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a molecularly imprinted graphene composite material with specific recognition function. The method is simple to operate, easy to control the reaction process, energy saving and environmental protection, and the prepared imprinted material has good selectivity, fast Adsorption, high binding capacity and reproducibility.

The technical scheme that realizes the object of the present invention is:

First, the graphene oxide is uniformly dispersed in the buffer solution, dopamine hydrochloride and template molecules are added to the obtained graphene oxide dispersion, the mixture is stirred, and finally centrifuged and washed to remove the template molecules by elution to obtain a molecularly imprinted graphene composite material .

Advantages of the present invention:

1. Graphene has a unique structure and excellent electrical, thermal, and mechanical properties. Compared with commonly used carrier materials, the thickness of graphene is very thin, so it endows MIPs with a large specific surface area.

2. The polydopamine membrane is stable, long-term durable, and has good biocompatibility and multifunctional groups, which can be used to imprint bioactive molecules.

3. Most of the traditional imprinting materials are resins. In the reaction process, not only an initiator needs to be added, but also most of the reactions need to be carried out under heating conditions. Bioactive substances such as proteins and enzymes are easily denatured under high temperature conditions. This invention only needs to add graphite oxide Graphene, template molecules, and dopamine are placed in a weak alkaline solution and stirred at room temperature to spontaneously form an adhesive polydopamine film on the surface of graphene oxide. The template molecules are wrapped in the film due to the force between them and dopamine. , during the self-polymerization of dopamine, graphene oxide is reduced to graphene (LiuH, JPhysChemC., 2012, 3334-3341). Finally, the template molecule is eluted, and the hole left after elution is required for the formation of Recognition site. The whole process does not require initiators and heating conditions. The thickness of polydopamine film can be controlled by the polymerization time and the amount of dopamine monomer added to reduce embedding phenomenon.

4. The molecularly imprinted graphene composite material obtained in the present invention has the characteristics of high binding capacity, fast adsorption and specific recognition for template molecules.

Detailed ways

In order to explain the present invention better, below in conjunction with specific embodiment the present invention is further explained in detail.

Example 1

Weigh 20mg of graphene oxide into a 100mL beaker, add 40mL of Tris buffer solution with pH=8.0, put it into an ultrasonic instrument and sonicate until GO is completely dispersed and dissolved, add 80mg of dopamine hydrochloride and 12mg of bovine hemoglobin into the beaker, and stir at 20°C Start the reaction, react for 12h. After stopping the reaction, wash with deionized water for three times, then add 60mL of methanol and acetic acid (volume ratio: 4:1) eluent to start elution, change the eluent every 4h, and wash the template molecule After cleaning, wash with deionized water three times to obtain molecularly imprinted graphene composites.

Example 2

Weigh 20mg of graphene oxide into a 100mL beaker, add 40mL of Tris buffer solution with pH=8.0, put it into an ultrasonic instrument and sonicate until GO is completely dispersed and dissolved, add 60mg of dopamine hydrochloride and 10mg of uracil into the beaker, and stir at 35°C Start the reaction and react for 12 hours. After stopping the reaction, wash with deionized water for three times, then add 60mL water to start elution, change the eluent every 4 hours, and the template molecules can be eluted to obtain molecularly imprinted graphene composites.

Claims (1)

1. a synthetic method of molecularly imprinted graphene composite material, it is characterized in that: first graphene oxide is uniformly dispersed in buffer solution, in the graphene oxide dispersion liquid that obtains, add dopamine hydrochloride and template molecule, mixed solution is carried out Stir, then centrifuge and wash, and finally elute to remove template molecules to obtain molecularly imprinted graphene composite materials; the preparation method of the graphene oxide dispersion is to add graphene oxide into the buffer solution and magnetically stir for 1 to 5 hours, and then ultrasonicate for 5 hours. ~30 minutes, the buffer is Tris buffer (trishydroxymethylaminomethane) or PBS (phosphate) buffer, pH=7.5~9.0, the concentration of graphene oxide in the solution is 0.01~5mg/mL: monomer The mass ratio of dopamine hydrochloride to graphene oxide is 0.5:1～5:1, the mass ratio of template molecule to graphene oxide is 0.1:1～3:1; the mixing solution mixing time of graphene oxide, dopamine hydrochloride and template molecule The stirring temperature is 10-40°C for 2h-12h; the eluent used for eluting template molecules is a polar solvent, and the polar solvent is selected from one or two mixed solvents of the following: water, acetic acid, ethanol, methanol, acetonitrile, N, N'-dimethylformamide, dimethyl sulfoxide, ethyl acetate, the volume ratio of the two solvents in the mixed solvent is 1:1~1:9; the template molecules used are selected from food safety testing, biopharmaceutical Or common molecules in the field of environmental monitoring. For food safety testing: antibiotics, hormones, Sudan red, melamine or caffeine; for biopharmaceuticals: epinephrine, purine bases, pyrimidine bases, DNA, proteins, enzymes, polypeptides or amino acids; Environmental monitoring selection: paraquat or vomitoxin.