CN116832173A

CN116832173A - preparation method of pH responsive nitrogen-containing metal organic framework and application of pH responsive nitrogen-containing metal organic framework as drug oral carrier

Info

Publication number: CN116832173A
Application number: CN202310614997.9A
Authority: CN
Inventors: 李丽; 祁赵蕊; 朱悦鸣; 李旭蕊; 刘宇
Original assignee: Liaoning University
Current assignee: Liaoning University
Priority date: 2023-05-29
Filing date: 2023-05-29
Publication date: 2023-10-03

Abstract

The invention relates to a preparation method of a pH responsive nitrogen-containing metal organic framework and application of the framework as a medicine oral carrier, belonging to the technical field of preparation of oral administration systems. The invention designs an oral delivery system of the entrapped non-steroidal anti-inflammatory drug loxoprofen, which is synthesized by a nitrogen-containing organic ligand and a zirconium ion cluster with low toxicity, and the drug-loaded system can not only prevent the degradation of a metal organic framework in the stomach and improve the stability of the loaded drug in the stomach acidic environment, avoid the premature leakage of the loaded drug, but also reduce the adverse reaction of the gastrointestinal tract of the non-steroidal anti-inflammatory drug loxoprofen, and can also slowly release the drug at the intestinal tract, improve the oral bioavailability of the drug and realize the pH responsive delivery of the drug.

Description

preparation method of pH responsive nitrogen-containing metal organic framework and application of pH responsive nitrogen-containing metal organic framework as drug oral carrier

Technical Field

The invention belongs to the technical field of preparation of oral administration systems, and particularly relates to a preparation method of a pH responsive nitrogen-containing metal organic framework and application of the framework as a medicine oral carrier.

Background

Metal-organic frameworks (Metal-Organic Frameworks), MOFs for short, are a new class of promising crystalline microporous materials, solid materials with periodic network structures, which are constructed by Metal ions or Metal clusters and organic bridging ligands through coordination, and the MOFs can be of one-dimensional, two-dimensional or three-dimensional structures. MOFs find wide range of applications including gas separation and storage, catalysis, sensing, fuel cells, electronics, drug delivery, and the like. The mechanism of changing the pore diameter of MOFs is mainly realized by changing the types of metal ions and organic ligands, and in theory, when the metal ions are the same, the structure of the organic ligands greatly affects the pore diameter, and the larger the organic ligands, the larger the pore diameter is. In addition, MOFs are structurally diverse, including cubes, polyhedra, diamonds, etc. This is mainly because of the wide range of alternatives, because of the variety of metal and organic ligands that make up MOFs. The metal constituting MOFs includes main group elements, transition elements, lanthanoids, etc., and the metal elements have various valence states and can be coordinated and combined differently. In addition, in the synthesis of MOFs, metal ions may interact with organic ligands and solvents (e.g., ethanol, N-dimethylformamide, etc.), but with subsequent processing, these species may also be removed to expose unsaturated metal sites. These metal sites can interact with groups in the drug molecule, thereby increasing the drug loading and stabilizing the drug loading. These unique advantages have led to extensive research into MOFs materials as a good drug carrier.

Loxoprofen (LOX) is an anionic drug, belongs to a commonly used nonsteroidal anti-inflammatory drug, and has better clinical effect and faster oral effect compared with similar clinical drugs. However, following oral administration, the structure of loxoprofen is often destroyed due to the strong acid environment of the stomach. Meanwhile, as with other antipyretic analgesic drugs, loxoprofen has a stimulating effect on the stomach, and can be prepared into an oral preparation with pH responsiveness, so that the drugs can be better protected, and meanwhile, side effects are reduced.

Current oral drug delivery systems face a number of challenges: many pharmaceutical active ingredients are hardly soluble or unstable and the distribution in the body is non-selective and therefore can be rapidly metabolized. This results in poor efficacy of the drug, which in turn results in low efficacy and high cost of treatment, while causing damage to healthy cells and tissues. For the above reasons, it is necessary to actively explore new strategies for oral administration. The novel drug delivery system can release drugs more specifically and has lower side effects, and the core is the selection of drug carriers, and the metal-organic framework has the advantages of the traditional inorganic materials and the emerging nano materials, so that the novel drug delivery system is one of the most promising drug carriers.

However, most MOFs have weak coordination bonds, are easily damaged by gastric acid, have poor stability in gastrointestinal conditions, and limit the application of MOFs in oral administration. Review of the data shows that with the development of nanotechnology in recent years, stimulus-responsive drug delivery systems have made great progress. The MOFs with pH responsiveness can realize targeted administration, sustained and controlled release administration, oral administration and the like. The nitrogen-containing UiO-66 series was found to be pH responsive because nitrogen-containing groups are readily protonated in acidic environments, but have more negative charge than the carbon atoms on the benzene ring in neutral or basic environments. The nitrogen group-containing organic ligands are capable of binding metal ions and the resulting MOFs will assume a positive state under acidic conditions. Therefore, such MOFs have a stronger electrostatic interaction with anionic drugs under acidic conditions, with rare pH-responsive release of anionic drugs compared to common MOF carriers. The MOF is more suitable to be used as an oral drug carrier by combining with the physiological environment characteristics of the gastrointestinal tract.

Disclosure of Invention

In order to solve the problems, the invention provides an oral drug carrier of a pH responsive nitrogen-containing metal organic framework, which takes zirconium-based metal clusters as metal ions and nitrogen-containing organic acids as ligands for connection, so that nitrogen-containing MOFs load anion drugs and can be better combined with the anion drugs in an acidic environment.

The technical scheme adopted by the invention is as follows:

the pH responsive nitrogen-containing metal organic framework is UiO-66-PDC which is prepared by taking Zr as a metal ion and pyridine 2, 6-dicarboxylic acid as an organic ligand through chemical reaction.

Further, the preparation method of the pH responsive nitrogen-containing metal organic framework comprises the following steps: sequentially adding ZrOCl into a container ₂ ·8H ₂ O, pyridine 2, 6-dicarboxylic acid, formic acid and deionized water are uniformly mixed and heated for reaction to obtain a milky white mixture, and the milky white mixture is cooled, centrifuged, washed and dried to obtain the UiO-66-PDC.

Further, in the pH responsive nitrogen-containing metal organic frame, the heating reaction temperature is 100-130 ℃ and the time is 2-5 h.

Further, in the above-mentioned pH-responsive nitrogen-containing metal organic frame, the drying temperature is 60 ℃.

The use of the above-described pH-responsive nitrogen-containing metal organic frameworks as pharmaceutical oral carriers.

Further, in the above application, the drug is loxoprofen, which is a non-steroidal anti-inflammatory drug.

Further, the above application method comprises the following steps: and dissolving loxoprofen in deionized water, dissolving UiO-66-PDC in ethanol, mixing the two solutions, performing ultrasonic dispersion, stirring, centrifuging, washing, centrifuging, and drying to obtain the medicine carrying metal organic framework LOX@UiO-66-PDC.

Furthermore, in the application, the mass ratio of the loxoprofen to the UiO-66-PDC is 1-2:1.

Further, in the above application, the stirring time is 8 hours.

Further, in the above application, the drying condition is: drying in a vacuum drying oven at 55 ℃ for 24 hours.

The beneficial effects of the invention are as follows:

1. currently, the metal ions used in metal organic framework materials are predominantly divalent or trivalent ions including 3d transition metals, 3p metals or lanthanides. Zirconium has low toxicity, good oxidation-reduction activity and photocatalysis performance, and is widely applied to metal organic frame materials. The UiO-66-PDC is a metal organic framework material with good crystal structure and super large specific surface area, and the metal organic framework material is constructed by organic ligand pyridine dicarboxylic acid and zirconium. Compared with other metal organic frame materials, the nitrogen-containing UiO-66 has the characteristics of larger specific surface area, porous rate, strong thermal stability, stronger acid resistance and the like. The invention can realize intestinal targeting of MOFs by loading the anionic drugs, so as to prepare the metal organic framework drug carrier with pH responsiveness, has the characteristics of high stability, good biocompatibility, easy degradation and the like, and can be applied to the drug carrier industry.

2. The preparation method of the UiO-66-PDC provided by the invention is simple, saves resources and is suitable for industrial mass production.

3. The UiO-66-PDC prepared by the invention can be used for loading LOX and other anionic drugs effectively, can release effective drug molecules in intestinal tracts, reduce the irritation of the drugs to the stomach, enhance the drug effect, quickly relieve the pain of patients and widen the application space of drug carriers.

4. The UiO-66-PDC prepared by the method has pH responsiveness, so that the MOF is easier to protonate in an acidic environment, and can be better combined with an anionic drug, thereby providing a design thought for the application of other oral drug carriers.

5. According to the invention, by introducing nitrogen atoms into the organic ligands of MOFs, pH responsiveness of MOFs can be realized, and targeted accumulation of anionic drug molecules in intestinal tracts can be realized, so that the drug carrier has the characteristics of high targeting property, remarkable effect and improvement of drug safety.

Drawings

FIG. 1 is an infrared spectrum of LOX, uiO-66-PDC, LOX@UiO-66-PDC and LOX & UiO-66-PDC.

FIG. 2 is a scanning electron microscope image of UiO-66-PDC (A) and LOX@UiO-66-PDC (B).

FIG. 3 is a DSC of LOX, uiO-66-PDC, LOX@UiO-66-PDC and LOX & UiO-66-PDC.

FIG. 4 is an XRD pattern for LOX@UiO-66-PDC and UiO-66-PDC.

FIG. 5 is a Zeta potential diagram of a UiO-66-PDC.

FIG. 6 is a graph of the release of LOX@UiO-66-PDC in artificial gastric juice and artificial intestinal juice.

FIG. 7 is a graph of blood plasma concentration versus time for LOX@UiO-66-PDC and LOX.

Detailed Description

The present invention is described in further detail below in conjunction with specific embodiments, which are not intended to limit the present invention, but are merely illustrative of the present invention.

Example 1

The test method is as follows:

1. synthesis of UiO-66-PDC

1.434g ZrOCl was weighed out ₂ ·8H ₂ O with 0.733g of pyridine 2, 6-dicarboxylic acid (H ₂ PDC), placed in a 50mL round bottom flask, added with 45mL formic acid and 5mL deionized water, and thoroughly mixed; placing the round bottom flask in an oil bath at 120 ℃ for reflux heating reaction for 3 hours to obtain milky suspension, cooling to room temperature, transferring into a 50mL centrifuge tube, and centrifuging; then washing with absolute ethyl alcohol, ultrasonic and centrifuging, and repeating the washing process for three times; and (3) after centrifugation, placing the product in a blast drying oven at 60 ℃ for drying to obtain the UiO-66-PDC.

2. Synthesis of LOX@UiO-66-PDC

30.0mg of Loxoprofen (LOX) is weighed and placed in a 100mL beaker, 10mL of deionized water is added for dissolving and standby, 20.0mg of UiO-66-PDC is weighed and dispersed in 10mL of ethanol by ultrasonic, and the two solutions are mixed (m) _LOX ：m _MOF After 20min of ultrasonic dispersion, the beaker was placed on a magnetic stirrer and stirred for 8h, centrifuged (10000 r/min,10 min), the product was washed with ethanol, centrifuged (5000 r/min,10 min), the solid product obtained by centrifugation was washed three times with ethanol to remove LOX adsorbed on the surface of the product, and the product was dried in a vacuum oven at 55 ℃ for 24h to obtain milky powder lox@uio-66-PDC.

3. Determination of loxoprofen content in LOX@UiO-66-PDC drug delivery System

And (3) measuring the LOX content at the wavelength of 222nm by adopting an ultraviolet spectrophotometry, and calculating the drug loading of the sample by using a formula (1).

4. In vitro dissolution test of LOX@UiO-66-PDC

LOX@UiO-66-PDC was placed in a dialysis bag containing 3mL of dialysate, fastened at both ends, placed in a 50mL centrifuge tube containing 20mL of dialysate, and subjected to an in vitro release test at 37℃with a constant temperature shaker (120 r/min). The dialysis medium is artificial gastric juice for 1-2 h, artificial intestinal juice for 2-6 h, and 0.5mL of release medium is taken every 0.5h in the in-vitro release process, and 0.5mL of fresh release medium solution is supplemented. The sample was filtered through a 0.45 μm microporous filter membrane, the primary filtrate was discarded, 20. Mu.L of the subsequent filtrate was taken, LOX content was measured by ultraviolet rays, the cumulative release rate (%) at each time point was calculated, and then an in vitro release curve was drawn with the release time as the abscissa and the cumulative release percentage as the ordinate.

Wherein C is _t The drug concentration (mg/min) in the release medium was measured for each time point, W was the total amount of drug administered (mg), V ₀ V is the volume of each sample for the total volume of the release medium.

5. Pharmacokinetic assay of LOX@UiO-66-PDC in rats

6 SD male rats were randomly divided into 2 groups (body weight 200+ -20 g), 3 per group, with the following experimental protocol:

LOX drug substance group: SD male rats were fasted 12 hours prior to dosing and were given LOX solution 5mg/mL by gavage at a dose of 50mg/kg. Blank blood is firstly taken before administration, 3.0mL of blood is taken through orbital venous sinus of a rat for 0.25, 0.5, 0.75, 1, 2, 3, 4, 6, 8, 10, 12 and 24 hours after administration, the blood is placed in a centrifuge tube (heparin sodium is attached to the tube wall), the blood is immediately centrifuged for 10 minutes at 12000r/min, and plasma is separated and stored in a refrigerator at the temperature of minus 20 ℃ for standby.

LOX@UIO-66-PDC group: SD male rats were fasted 12h prior to dosing and given the drug-loaded UiO-66-PDC (50 mg/kg calculated as LOX) by gavage. Blank blood is firstly taken before administration, 3.0mL of blood is taken through orbital venous sinus of a rat for 0.25, 0.5, 0.75, 1, 2, 3, 4, 6, 8, 10, 12 and 24 hours after administration, the blood is placed in a centrifuge tube (heparin sodium is attached to the tube wall), the blood is immediately centrifuged for 10 minutes at 12000r/min, and plasma is separated and stored in a refrigerator at the temperature of minus 20 ℃ for standby.

(II) detection and characterization

1. FIG. 1 is a diagram of LOX, uiO-66-PDC, LOX@UiO-66-PDC and a physical mixture of LOX and UiO-66-PDC (LOX)&UiO-66-PDC), as can be seen from FIG. 1, at 744cm ^-1 The characteristic peak at the position is the bending vibration peak of-CH on benzene ring, 3700cm ^-1 ～3000cm ^-1 A broad area peak corresponding to the stretching vibration peak of O-H bond of 1640cm ^-1 Asymmetric stretching vibration peak corresponding to carboxylic acid group, 1373cm ^-1 Symmetrical telescopic vibration peak corresponding to carboxylic acid group, 1652cm ^-1 C=o stretching vibration peak corresponding to carboxyl group. LOX characteristic peak of 1750cm ^-1 ～1250cm ^-1 The regional triplet, LOX, and UiO-66-PDC powder were physically mixed and the characteristic peak was still present, and the LOX at UiO-66-PDC was not seen as the LOX characteristic peak, which showed successful loading of LOX into the UiO-66-PDC.

2. FIG. 2 is an SEM image of UiO-66-PDC and LOX@UiO-66-PDC, and as can be seen from FIG. 2A, the particle size distribution of the UiO-66-PDC is uniform, the structure is a regular sixteen-surface structure, and the particle size is about 200 nm; as can be seen from FIG. 2B, the crystal structure of the UiO-66-PDC after drug loading still has a good regular octahedral structure, and the particle size is not changed obviously, which indicates that the crystal structure of the UiO-66-PDC is not affected in the drug loading process.

3. FIG. 3 is a DSC plot of LOX, uiO-66-PDC, LOX@UiO-66-PDC, and a physical mixture of LOX and UiO-66-PDC (LOX & UiO-66-PDC), and as can be seen from FIG. 3, the comparative heat absorption curve, LOX@UiO-66-PDC is similar to UiO-66-PDC, with no absorption peak of LOX. The heat absorption curves for LOX@UiO-66-PDC and LOX & UiO-66-PDC are significantly different, indicating that LOX is entrapped in the carrier UiO-66-PDC.

4. FIG. 4 is an XRD pattern for LOX@UiO-66-PDC and UiO-66-PDC, and as can be seen from FIG. 4, the XRD patterns of UiO-66-PDC are almost identical before and after drug loading, and all show high-intensity sharp diffraction, which indicates that the crystal form structure of the UiO-66-PDC is not changed after drug loading, and the diffraction peak of the LOX in the UiO-66-PDC in the LOX@UiO-66-PDC is covered, so that the crystal form property of the LOX is not revealed, and that the LOX is successfully loaded into the UiO-66-PDC.

5. FIG. 5 is a graph showing the particle size distribution of UiO-66-PDC. As can be seen from FIG. 5, the average particle size of UiO-66-PDC is 232.+ -.10 nm, and the particle size distribution is uniform, thus the UiO-66-PDC can be used as a good drug carrier.

6. The loading of LOX@UiO-66-PDC in this example was 75.6%.

7. FIG. 6 is a graph of LOX@UiO-66-PDC release in artificial gastric juice and artificial intestinal juice, showing that the drug release rate is slower in artificial gastric juice at pH 1.2; in the artificial intestinal juice with pH of 6.8, the release rate of LOX begins to be accelerated, and finally in the artificial intestinal juice with pH of 7.2, the release of the medicine becomes slow until the accumulated release rate is not changed obviously. The LOX@UiO-66-PDC cumulative release rate is about 13.2% under the artificial gastric juice environment, then the artificial small intestine environment is entered, the cumulative release rate is continuously increased, 69.8% after 4 hours, the drug release rate after the artificial intestinal juice is entered is obviously slow, the 8-hour curve tends to be stable, no obvious change occurs any more, and the final cumulative release amount is 78.6%. From the release profile of LOX@UiO-66-PDC it can be found that: the release of LOX goes through a slow release phase (initial 2 h), followed by a fast release phase (from 2 to 4 h) and finally the release becomes slow again (from 4 to 6 h). In artificial gastric juice, the release rate of LOX is slow; in the artificial intestinal juice environment, the release rate of LOX from the carrier is accelerated. For example, the LOX@UiO-66-PDC set has an accumulated release rate of about 2.3% in an artificial gastric juice environment, and can maintain the stability of the drug delivery system and reach the small intestine. When entering the small intestine part, the accumulated release rate of LOX@UiO-66-PDC is continuously increased, and the accumulated release rate reaches 60% in 6 hours. The results show that the LOX@UiO-66-PDC drug delivery system can protect LOX from smoothly passing through the stomach to reach the intestinal tract, so that the drug is released, and the drug effect is exerted.

8. FIG. 7 shows the blood mass concentrationTime graph, as can be seen from FIG. 7, T of LOX group _max 0.75h, C _max T after drug loading into UiO-66-PDC at 23.48 μg/mL _max 1.5h, C _max About 17.26. Mu.g/mL. The peak reaching time of the LOX@UiO-66-PDC group is longer than that of the LOX group, the peak reaching concentration is lower than that of the LOX group, and the blood concentration curve of the LOX@UiO-66-PDC is also gentle, so that the release of the medicine is delayed, the release time of the LOX can be prolonged, and the requirement of improving the release concentration of the medicine can be met, and the medicine delivery system can reduce the blood peak concentration, delay the peak reaching time of the medicine in a body and maintain the stable blood concentration. The drug delivery system can prolong the release time of loxoprofen and improve the release concentration of the drug, so that the drug is absorbed and utilized to a better degree.

Claims

The pH responsive nitrogen-containing metal organic framework is characterized in that Zr is used as a metal ion, pyridine 2, 6-dicarboxylic acid is used as an organic ligand, and the pH responsive nitrogen-containing metal organic framework UiO-66-PDC is prepared through chemical reaction.
2. The pH-responsive nitrogen-containing metal-organic framework of claim 1, wherein the method of preparation is as follows: sequentially adding ZrOCl into a container ₂ ·8H ₂ O, pyridine 2, 6-dicarboxylic acid, formic acid and deionized water are uniformly mixed and heated for reaction to obtain a milky white mixture, and the milky white mixture is cooled, centrifuged, washed and dried to obtain the UiO-66-PDC.
3. The pH-responsive nitrogen-containing metal-organic framework of claim 2, wherein the heating reaction temperature is 100-130 ℃ for a period of 2-5 hours.
4. The pH-responsive nitrogen-containing metal organic framework of claim 2, wherein the drying temperature is 60 ℃.
5. Use of the pH-responsive nitrogen-containing metal organic framework of claim 1 as an oral carrier for a pharmaceutical.
6. The use according to claim 5, wherein the drug is loxoprofen, a non-steroidal anti-inflammatory drug.
7. The use according to claim 6, characterized in that the method is as follows: and dissolving loxoprofen in deionized water, dissolving UiO-66-PDC in ethanol, mixing the two solutions, performing ultrasonic dispersion, stirring, centrifuging, washing, centrifuging, and drying to obtain the medicine carrying metal organic framework LOX@UiO-66-PDC.
8. The use according to claim 7, wherein the mass ratio of loxoprofen to UiO-66-PDC is 1-2:1.
9. The use according to claim 7, wherein the stirring time is 8 hours.
10. The use according to claim 7, wherein the drying conditions are: drying in a vacuum drying oven at 55 ℃ for 24 hours.