MOLECULE CARRIER AND METHOD FOR PREPARING THE SAME

Abstract

The invention provides a molecule carrier, comprising a metal-organic framework having an interior space and a surface of the metal-organic framework has a plurality of pores; and a molecule embedded in the interior space of the metal-organic framework. The invention also provides a method for preparing the molecule carrier by a de novo approach, comprising mixing a solution containing metal ions, an organic ligand, a molecule, and a surface coating agent to form an aqueous mixture. After incubating for a few minutes, the aqueous mixture is subjected to a drying process to obtain the molecule carrier.

Claims

1. A molecule carrier, comprising: a metal-organic framework having an interior space and a surface of the metal-organic framework has a plurality of pores; and a molecule embedded in the interior space of the metal-organic framework.

2. The molecule carrier as claimed in claim 1, wherein a diameter of the pores is smaller than a size of the molecule.

3. The molecule carrier as claimed in claim 1, wherein the metal-organic framework is a transition metal-based metal-organic framework.

4. The molecule carrier as claimed in claim 1, wherein the molecule is DNA, RNA, a protein, a drug, an inhibitor, or the combination thereof.

5. The molecule carrier as claimed in claim 1, wherein the molecule is an enzyme.

6. A method for preparing a molecule carrier, comprising: mixing a solution containing metal ions, an organic ligand, a molecule, and a surface coating agent to form an aqueous mixture, and then drying the aqueous mixture.

7. The method as claimed in claim 6, wherein the method is performed at 4 C. to 60 C.

8. The method as claimed in claim 6, wherein the solution containing metal ions is a solution containing transition metal ions.

9. The method as claimed in claim 6, wherein the organic ligand is imidazole-2-carboxaldehyde, 2-methyl imidazole, imidazole derivatives, or terephthalic acid and derivatives thereof.

10. The method as claimed in claim 6, wherein the molecule is DNA, RNA, a protein, a drug, or an inhibitor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is a schematic view of a structure of a preferred example of a molecule carrier of the invention;

[0029] FIGS. 2A and 2B are respectively a scanning electron microscope (SEM) image and an X-ray diffraction (XRD) pattern of a preferred example of a molecule carrier of the invention;

[0030] FIGS. 3A and 3B are respectively a nitrogen sorption isotherm and a TAG curve of a preferred example of a molecule carrier of the invention;

[0031] FIGS. 4A and 4B show that catalase and myoglobin are embedded into the metal-organic framework ZIF-90 of a molecule carrier of the invention; and

[0032] FIG. 5 shows a kinetic of H.sub.2O.sub.2 degradation by a preferred example of a molecule carrier of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0033] In order for a person skilled in the art to understand the purposes, technical features, and advantages of the invention, the following descriptions will be described in detail with drawings and preferred embodiments of the invention.

Example 1

[0034] Zinc nitrate (371.3 mg) was added to deionized water (3.0 mL) to form an aqueous zinc nitrate solution at room temperature of 20 C. to 30 C.

[0035] Meanwhile, at 42 C., imidazole-2-carbaldehyde (ICA, 480.0 mg), polyvinylpyrrolidone (PVP, 50.0 mg), and catalase extracted from bovine liver (25.0 mg) were dissolved in deionized water (25.0 mL) to form an mixture. The mixture was then mixed with the said aqueous zinc nitrate solution to form an aqueous mixture. The aqueous mixture was stirred for about 10 minutes.

[0036] Subsequently, the said aqueous mixture was subjected to centrifugation at 14,000 g. The obtained product was rinsed by deionized water followed by drying in vacuum at room temperature to obtain a molecule carrier (hereinafter, referring as CAT@ZIF-90).

Example 2

[0037] Fluorescently labeled-catalase molecule (FITC-CAT) was synthesized and replaced the catalase of Example 1. The molecule carrier of Example 2 was synthesized in a manner same as Example 1 to obtain a molecule carrier (hereinafter, referring as FITC-CAT@ZIF-90).

Comparative Example 1

[0038] Except for not adding the catalase extracted from bovine liver, the preparation steps were the same as described in Example 1 to obtain a molecule carrier (hereinafter, referring as ZIF-90).

Comparative Example 2

[0039] The ZIF-90 of Comparative Example 1 and the catalase of Example 1 were physically mixed by stirring to obtain a molecule carrier. In the molecule carrier of Comparative Example 2, the catalase adsorbed only on the outer surface of the ZIF-90 (hereinafter, referring as CAT-on-ZIF-90).

Comparative Example 3

[0040] The ZIF-90 of Comparative example 1 and the fluorescently labeled-catalase molecule (FITC-CAT) were physically mixed by stirring to obtain a molecule carrier. In the molecule carrier of Comparative Example 3, the fluorescently labeled-catalase molecule (FITC-CAT) adsorbed only on the outer surface of the ZIF-90 (hereinafter, referring as FITC-CAT-on-ZIF-90).

Experimental Example 1

Structure of CAT@ZIF-90

[0041] FIG. 1 is a schematic view of a structure of a molecule carrier 100 of the invention. The molecule carrier 100 comprises a metal-organic framework (MOF) 101 (ZIF-90). The metal-organic framework (MOF) 101 has an interior space and a surface of the metal-organic framework (MOF) 101 also has a plurality of pores. Molecule 102 (catalase) is embedded in the interior space of the metal-organic framework (MOF) 101. The structure of CAT@ZIF-90 of Example 1 was observed using a scanning electron microscope (SEM), which is shown in FIG. 2A. As shown, CAT@ZIF-90 has a uniform size of about 1-2 m. According to the X-ray diffraction (XRD) patterns shown in FIG. 2B, there were no significant differences in the crystal structures and degrees of crystallinity of CAT@ZIF-90 and ZIF-90.

[0042] Next, the porous features of CAT@ZIF-90 and ZIF-90 were investigated using nitrogen sorption isotherms obtained by Micromeritics ASAP 2010 analyzer. As shown in FIG. 3A, the results obtained were similar to typical adsorption isotherm Type I (also known as Langmuir type). Therefore, CAT@ZIF-90 and ZIF-90 can be deemed to have microporous structures.

[0043] In addition, specific surface areas calculated by Langmuir and BET adsorption-desorption isotherm models are shown in Table 1. Since the catalase was embedded into the porous material; thus, the catalase occupied part of the surface area of the porous material. As a result, as shown in Table 1, CAT@ZIF-90 has smaller Langmuir surface area (S.sub.L), BET surface area (S.sub.BET), and total pore volume than ZIF-90.

TABLE-US-00001 TABLE 1 t-plot Langmuir total micropore surface pore volume: area: S.sub.L S.sub.BET volume V.sub.micro (m.sup.2/g) (m.sup.2/g) (cm.sup.3/g) (cm.sup.3/g) Comparative example 1: 1309 992 0.55 0.38 ZIF-90 Example 1: CAT@ZIF-90 1111 843 0.47 0.37

[0044] FIG. 3B shows a result of Thermogravimetric Analysis (TGA), which measures weight change of a sample under a specific temperature condition to provide information of weight loss with respect to the temperature of a sample. As shown, at about 320 C., CAT@ZIF-90 had a slight weight loss compared to ZIF-90. The pattern of CAT@ZIF-90 was similar to the catalase decomposition curve, indicating catalase decomposition in CAT@ZIF-90. In other words, the result confirmed the existence of catalase in CAT@ZIF-90.

Experimental Example 2

[0045] Catalase was indeed embedded in the metal-organic framework (MOF) ZIF-90.

[0046] Experimental Example 2 confirmed that the catalase was indeed embedded in the metal-organic framework (MOF) ZIF-90 instead of being absorbed on the external surface of the metal-organic framework (MOF) ZIF-90. In Experimental Example 2, after rinsing CAT@ZIF-90 of Example 1 and CAT-on-ZIF-90 of Comparative Example 2 by deionized water, an acid was used to dissolve the metal-organic framework (MOF) material to release the molecule (protein). The molecule (protein) was then analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). As shown in FIG. 4A, column 1 was the catalase of Example 1 (L1), column 2 was CAT-on-ZIF-90 of Comparative Example 2 (L2), and column 3 was CAT@ZIF-90 of Example 1 (L3). Proteins with a molecular weight of about 60 KDa were detected in L1 and L3, which corresponded to a single molecular weight of the catalase of Example 1. However, such protein was not detected in L2. The result suggested that the catalase was embedded into ZIF-90 of Example 1; thus, the catalase could not be washed away easily by deionized water. On the contrary, in Comparative Example 2, the catalase was adsorbed on the surface of ZIF-90; thus, the catalase could be washed away easily by deionized water.

[0047] Another experiment was conducted to prove that the catalase was embedded into the metal-organic framework (MOF) ZIF-90. Specifically, FITC-CAT@ZIF-90 of Example 2 and FITC-CAT-on-ZIF-90 of Comparative Example 3 were observed using a confocal microscope. The results are shown in FIG. 4B. (Note that in order to protect the catalase from being washed away, the rinsing step of the molecule carrier of Comparative Example 3 was omitted). As shown in FIG. 4B, the fluorescence of FITC-CAT@ZIF-90 of Example 2 had a more uniform distribution (FIG. 4B, left) compared to the fluorescence of FITC-CAT-on-ZIF-90 of Comparative Example 3, which distributed only at the edge (FIG. 4B, right). The result indicated that the catalase was embedded in the metal-organic framework (MOF) in Example 2 rather than being adsorbed onto a surface of the metal-organic framework (MOF) in Comparative Example 3.

Experimental Example 3

[0048] The preparation method of the invention retained the biological activity of the molecule.

[0049] It is known that catalase can decompose hydrogen peroxide to water and oxygen. In Experimental Example 3, degradation kinetics of hydrogen peroxide were studied to evaluate the biological activity of the catalases embedded into a metal-organic framework (MOF) prepared via an aqueous phase-preparation method (present invention) and a conventional alcohol phase-preparation method.

[0050] FIG. 5 shows result of FOX assay. During FOX assay, iron divalent ions (Fe.sup.2+) of the FOX reagent will react with the remaining hydrogen peroxide and become iron trivalent ions (Fe.sup.3+). The said iron trivalent ions (Fe.sup.3+) and xylenol orange will form complexes under slightly acidic condition. A good linear absorption intensity at UV-Vis 560 nm will be obtained. Thereby, a concentration of hydrogen peroxide will be obtained indirectly. As shown in FIG. 5, CAT@ZIF-90 of Example 1 was measured to have an observed rate constant (k.sub.obs) of 0.0268 S.sup.1. However, the biological activity of the catalase immobilized on the molecule carrier obtained by the conventional alcohol phase-preparation method (referring as control group 1; the preparation method was the same as Example 1 except alcohol was used as the solvent instead of water) could not be detected. This was possibly due the destruction of the catalase by the organic solvent (alcohol).

[0051] It is also known that enzyme (catalase) activity might be affected by substances existed in the environment. For example, enzyme (catalase) activity may be weakened by substances in the environment. To prove the embedded catalase of CAT@ZIF-90 of Example 1 can be protected from substances in the environment, free catalase (referring as control group 2; the free catalase meant the catalase was not being bound to any carrier) and CAT@ZIF-90 of Example 1 were respectively mixed with proteinase K. It should be noted that proteinase K has a molecular size of 68.368.3108.5 (28.5 kDa), which is greater than the pore size of CAT@ZIF-90 of Example 1. As shown in FIG. 5, the free catalase was inhibited by protease K and its enzyme activity was lost in control group 2 (control group 2: catalase+protease K). In contrast, the enzyme activity of the catalase molecule of CAT@ZIF-90 was maintained (k.sub.obs=0.0246 S.sup.1) (Example 1+protease K).

[0052] In addition to the aforesaid catalase as the molecule embedded into the metal-organic framework (MOF) ZIF-90, another example of the invention used myoglobin as the molecule to be embedded into the metal-organic framework (MOF) ZIF-90, named as Myoglobin@ZIF-90. The preparation method of Myoglobin@ZIF-90 was the same as that of the Example 1, except that myoglobin was used to replace the catalase of Example 1.

[0053] As shown in FIG. 2B, there were no significant differences in the crystal structures and degrees of crystallinity between Myoglobin@ZIF-90 and CAT@ZIF-90 and ZIF-90.

[0054] Moreover, following a method similar to Comparative Example 2, myoglobin was mixed with ZIF-90 and myoglobin was adsorbed onto the external surface of ZIF-90, named as Myoglobin-on-ZIF-90. Furthermore, following the same manner as Experimental Example 2, the sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) results indicated that myoglobin was indeed embedded into ZIF-90 rather than being adsorbed onto the external surface of ZIF-90. Specifically, please refer to FIG. 4, L4 represented myoglobin, L5 represented Myoglobin-on-ZIF-90, and L6 represented Myoglobin@ZIF-90. As shown in FIG. 4, myoglobin was detected in L4 and L6 but was not detected in L5. This result suggested that myoglobin was embedded into ZIF-90 so that myoglobin could not be washed away easily by deionized water.

[0055] Although the invention has been explained in relation to its preferred embodiments, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.