A microalgae-based oral micro-nano drug delivery system, and a preparation method and use thereof

Abstract

This invention discloses an oral micro / nano-drug delivery system based on microalgae, its preparation method, and its applications. This oral micro / nano-drug delivery system, composed of microalgae and drug materials, enhances drug retention time in the gastrointestinal tract and improves distribution throughout the intestinal lumen, thus exerting a long-lasting protective and nourishing effect. This oral micro / nano-drug delivery system simultaneously kills gastrointestinal bacterial pathogens, strengthens the epithelial-mucosal barrier, provides nutrients, regulates inflammation, and modulates intestinal microbiota diversity, fully exerting its protective effect against gastrointestinal damage caused by acetic acid, alcohol, and infection. It exhibits good oral safety, and its preparation process is simple and easy, overcoming the problems of existing biological agents that struggle to simultaneously alleviate symptoms and repair barrier function, complex drug loading and modification processes, difficulty in maintaining biological activity, high costs, and limitations in large-scale production. It has broad application prospects in the field of gastrointestinal drug delivery.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical formulation technology, specifically relating to an oral micro / nano drug delivery system for gastrointestinal administration, its preparation method, and its application in the preparation of gastrointestinal acetic acid-alcohol and infection-induced damage protection, nutritional supplementation, and inflammation regulation drugs. Background Technology

[0002] Oral administration is considered the preferred route of drug delivery due to its safety, non-invasiveness, low cost, high patient compliance, and associated benefits with targeted or localized therapies, such as those for gastrointestinal disorders. However, gastric emptying limits drug retention and absorption in the stomach, and the acidic environment and proteases can also affect drug activity, especially for biologics. To retain drugs in the stomach, strategies such as increasing adhesion, altering shape, using microneedles, and generating buoyancy have been employed, such as "floating systems" for diltiazem, verapamil, etc. These flotation systems can reduce their density by swelling or generating gas, thereby promoting their floating in gastric juices. Compared to other strategies, flotation systems have been well-developed and widely used clinically, but primarily as tablets designed to carry drugs and maintain buoyancy. This is not ideal for patients with dysphagia, as the swelling or gas generated by the tablet in the stomach can cause indigestion or even worsen existing gastric conditions.

[0003] Dietary-induced gastrointestinal inflammation remains a central global health concern. Peptic ulcers, commonly occurring in the stomach and duodenum, represent a significant health burden. They are associated with a variety of factors, including infections (Helicobacter pylori), dietary habits, medications (nonsteroidal anti-inflammatory drugs, alcohol), and stress. These factors impair normal mucosal defense and repair, making the mucosa more susceptible to acid erosion. Antibiotics, bismuth preparations, prostaglandin analogs, and acid inhibitors, such as proton pump inhibitors and H2 receptor antagonists, are first-line treatments for peptic ulcers, but they do not help with impaired mucosal defense and repair functions and exhibit poor adherence. Furthermore, long-term use of proton pump inhibitors and antibiotics may lead to intestinal infections.

[0004] Clostridium difficile, Salmonella, and Escherichia coli have become the most common bacterial pathogens causing gastroenteritis, overcoming various intestinal colonization resistance factors such as antimicrobial secretion, nutrient competition, epithelial cell barrier, and immune activation. Diarrhea and invasive infections caused by non-typhoidal Salmonella infection constitute the largest burden among foodborne pathogens. In recent decades, the overuse of antibiotics in the swine and poultry industries to combat pathogens such as Salmonella has led to a year-on-year increase in antibiotic resistance and multidrug resistance. Current treatments, such as antibiotics and intravenous fluids, only relieve symptoms but have no substantial beneficial effect on the damaged mucosal barrier or reducing mucosal inflammation. Furthermore, antibiotics are not beneficial in improving diarrhea symptoms in patients with non-typhoidal Salmonella infection. Levofloxacin combined with cimetidine is effective in treating bacterial acute gastroenteritis, but its adverse effects are significant. In addition, antibiotic overuse can produce serious side effects, including intestinal microbiota dysbiosis, musculoskeletal disorders, and irreversible neurological damage.

[0005] In recent years, drug carriers based on various microorganisms such as bacteria, blood cells, and microalgae have attracted widespread research interest due to their unique biological functions. Research on microbial carriers has primarily focused on intravenous injection or enteral administration, and reports on large-scale production are scarce. The reasons for this can be analyzed from aspects such as production processes, costs, and oral metabolic safety. 1. Traditional drug loading processes require high-concentration drug culture of microorganisms for extended periods, which is complex and demands sophisticated equipment. The special modification of microorganisms and multi-step processing steps are cumbersome, requiring specialized equipment and technicians to ensure accuracy, as well as specific production environments, increasing equipment costs and site requirements.

[0006] 2. Traditional drug delivery processes consume large amounts of drug resources, have long production cycles leading to increased labor costs, require significant investment in quality control, and result in higher scrap rates due to the complexity of the processes, thus driving up product prices and posing challenges to the large-scale commercial application of microbial carriers.

[0007] 3. After the microbial system enters the human body, gastric emptying, acidic environment, and proteases will destroy its biological activity and reduce the efficacy of the drug.

[0008] Patents (CN105726609A, CN110205288B) disclose several methods for preparing oral gastrointestinal drugs and their applications. Although these methods achieve the goals of terminating inflammation and repairing the digestive tract, they inevitably suffer from short gastrointestinal retention times, complex preparation processes, and high costs, making them unsuitable for large-scale production and application. The complex environment of the gastrointestinal tract severely affects drug retention and absorption within the digestive system.

[0009] Currently, microalgae-based biofloating drug delivery systems for gastric retention, with spirulina, resveratrol, and bismuth pectin as their core components, can only protect against alcohol-induced gastrointestinal and liver damage. They are unable to address more common clinical issues such as infectious gastroenteritis and chemically induced gastric damage, resulting in limited functional coverage. They only provide nutrient supplementation and regulate intestinal inflammation, lacking the ability to repair the gastrointestinal mucosal barrier. Oral microalgae nanocomposite radiation protection formulations, using microalgae and PLGA drug-loaded nanoparticles as their core components, involve complex and cumbersome preparation processes, using toxic organic solvents such as dichloromethane and acetone, increasing safety risks. Similarly, they lack antibacterial activity and mucosal barrier repair capabilities. Furthermore, these oral drug delivery systems are highly dependent on the activity of resveratrol and astaxanthin; these drugs are expensive, their activity is highly dependent on the extraction source, and there are significant batch-to-batch quality variations, limiting their application.

[0010] To date, no novel gastrointestinal retention drugs or drug complexes have been developed that combine multiple functions such as long-lasting and stable efficacy, good distribution, few side effects, restoration of damaged mucosal defense and repair functions, and low cost. Therefore, the research and development of related drugs and formulations has become a top priority in addressing the gastrointestinal drug delivery problem. Summary of the Invention

[0011] To address the shortcomings of existing technologies, the present invention aims to provide an oral micro / nano-drug delivery system for gastrointestinal drug administration, its preparation method, and its applications. This oral micro / nano-drug delivery system overcomes the limitations of existing gastrointestinal retention systems, such as their inability to restore damaged mucosal defense and repair functions and their impact on normal gastric digestion. It also overcomes the shortcomings of existing biological agents, such as difficulty in prolonged retention and poor distribution in the gastrointestinal tract, complex drug loading and modification processes, difficulty in maintaining biological activity, high costs, and difficulties in large-scale production. This system achieves low-cost and rapid drug loading of biological carriers, maintains carrier biological activity, achieves prolonged gastrointestinal retention and sustained drug release, enhances the gastrointestinal absorption and local therapeutic effects of microalgae and drugs, and promotes mucosal defense and repair functions. The preparation process is simple, highly feasible, and easily scalable. This drug delivery system can also provide small amounts of proteins, unsaturated fatty acids, and trace elements required by the human body.

[0012] The first objective of this invention is to provide an oral micro / nano-drug delivery system based on microalgae for gastrointestinal drug administration. This system comprises natural microalgae and a drug to be loaded to enhance its gastrointestinal retention capacity. Both the natural microalgae and the micro / nano-drug delivery system are micrometer-sized. In this system, the drug and the natural microalgae are bound together through spatial structure, natural material adhesion, and physical adsorption. Under absorption spectral scanning conditions in the 200-600 nm range, the bio-micro / nano-drug delivery system exhibits characteristic peaks at 440 nm and the corresponding drug absorption peak.

[0013] Preferably, the oral micro / nano drug delivery system further comprises a solvent selected from at least one or more of sterile phosphate buffer, ultrapure water, distilled water, or physiological saline.

[0014] Preferably, the oral micro / nano drug delivery system has long-lasting retention and slow degradation properties in the gastrointestinal tract, wherein long-lasting retention and slow degradation in the gastrointestinal tract mean that the fluorescence signal in the gastrointestinal tract can still be detected more than 3 hours after administration; preferably, the detection method is: administering a certain dose to Balb / c mice that have been fasted for 24 hours by gavage, and the fluorescence image after the action shows that the gastrointestinal tract still contains the drug complex; preferably, the certain dose is 10-200 mg / kg, more preferably, the certain dose is 100 mg / kg; further preferably, the action time is 24 hours; more preferably, the fluorescence image uses a chlorophyll channel with Cy5.5, an excitation wavelength of 605 nm, and an emission wavelength of 615-665 nm.

[0015] Preferably, the oral micro / nano drug delivery system has oral safety, which is tested by administering a certain dose to Balb / c mice by gavage once a day. After continuous administration, the weight of the mice remains unchanged, and hematological indicators and liver and kidney function show normality. Preferably, the certain dose is 1-100 mg / kg, more preferably, the certain dose is 50 mg / kg, and further preferably, the continuous administration is for 5 days.

[0016] Preferably, the oral micro / nano drug delivery system has the following characteristics: (1) It appears as a blackish-green suspension; (2) It retains the biological activity of natural microalgae; (3) It retains the fluorescence imaging function of natural microalgae.

[0017] Preferably, the mass ratio of the natural microalgae to the drug is 1:0.1-1:1.

[0018] Preferably, the natural microalgae is Spirulina.

[0019] Preferably, the drug is dopamine-modified zinc oxide nanoparticles.

[0020] Preferably, the length of the spirulina is 100-500 μm.

[0021] The second objective of this invention is to provide a method for preparing an oral micro / nano drug delivery system based on microalgae, the method comprising the preparation of a drug solution and a natural microalgae biological system; the method includes the following steps: (1). Preparation of natural microalgae and drug solution: Take micron-sized microalgae culture, centrifuge and discard the supernatant or use a sieve to filter and remove the culture medium, wash the precipitate and collect it to obtain fresh natural microalgae, and resuspend it to obtain spirulina suspension.

[0022] Preferably, the centrifugation speed and time are 4000 rpm and 10 min, respectively, and the sieve is 200 mesh.

[0023] Preferably, the solution for washing the precipitate is selected from at least one of sterile phosphate buffer, ultrapure water, distilled water, or physiological saline.

[0024] Preferably, the washing and settling process is performed 3-5 times; Weigh out zinc acetate and sodium hydroxide solids, dissolve them separately in ultrapure water, and then dilute to obtain 10-20 mg / mL zinc acetate and 10-200 mg / mL sodium hydroxide solutions. Add 50 mg of dopamine hydrochloride to 20 mL of zinc acetate solution beforehand, and then add 500 μL of sodium hydroxide solution dropwise while stirring. Continue heating and stirring, and then centrifuge. After centrifugation, collect the precipitate and resuspend it to obtain a suspension of dopamine-modified zinc oxide nanoparticles.

[0025] Preferably, the diluent is selected from at least one of sterile phosphate buffer, ultrapure water, distilled water, or physiological saline.

[0026] (2). Preparation of drug complex: Under specific conditions, add the Spirulina suspension obtained in step (1) to the dopamine-modified zinc oxide nanoparticle suspension, stir, then centrifuge and collect the precipitate, wash 3-5 times, and then process to obtain the suspension of drug complex.

[0027] Preferably, the stirring speed is 60-200 rpm.

[0028] Preferably, the stirring time is 0.5-6 h.

[0029] Preferably, the mass ratio of the suspension of spirulina and the drug complex is 1:0.1-1:1; More preferably, the mass ratio of the spirulina and the drug complex suspension is 1:1.

[0030] Preferably, the solvent used in the preparation of the suspension is selected from at least one of sterile phosphate buffer, ultrapure water, distilled water, or physiological saline.

[0031] A third object of the present invention is to provide a pharmaceutical composition comprising at least one active ingredient and at least one pharmaceutically acceptable additive, wherein the active ingredient is the aforementioned microalgae-based oral micro / nano drug delivery system.

[0032] Preferably, the additive is selected from any one or more of sterile phosphate buffer, physiological saline, ultrapure water or distilled water.

[0033] A fourth objective of this invention is to provide the use of the above-described microalgae-based oral micro / nano-drug delivery system in the preparation of drugs related to the treatment of abdominal diseases.

[0034] Preferably, the abdominal disease is selected from any one of alcohol, acetic acid, or infectious lesions.

[0035] Preferably, the infectious lesion is caused by Salmonella infection.

[0036] Preferably, the bacterial injury is selected from at least one of gastric injury, intestinal injury, or bacteremia injury caused by the circulatory system; further, the gastric injury, intestinal injury, or blood or visceral injury is preferably gastritis, enteritis, and bacteremia.

[0037] Preferably, after oral administration, the microalgae-based oral micro / nano drug delivery system or drug composition, after oral administration, partially enters the stomach and rapidly forms a film, encapsulating the microalgae and adhering to the stomach wall, where it remains for a prolonged period, slowly releasing the drug. The remaining portion enters various segments of the intestine, comprehensively covering and distributing throughout the proximal, mid, and distal segments through the unique spiral structure of the microalgae, significantly improving drug release and absorption in intestinal tissues. This fully exerts its protective effect on gastrointestinal tissues and cells, while simultaneously upregulating the levels of intestinal tight junction proteins and mucins, protecting the circulatory system.

[0038] Preferably, the oral micro / nano drug delivery system or drug composition based on microalgae adheres to the stomach wall or intestinal villi without affecting the normal eating and digestive process.

[0039] Preferably, the oral micro / nano drug delivery system or drug composition based on microalgae, when applied in clinical practice for acute oral administration of alcohol or acetic acid, or for protection against excessive gastric acid caused by diet, or for protection against damage caused by acute infection, exhibits good biocompatibility. Through the gastrointestinal protective effect and sustained-release effect of microalgae, the potential side effects of dopamine-modified zinc oxide nanoparticles can be effectively avoided, making it suitable for daily and long-term oral use.

[0040] Preferably, the oral micro / nano drug delivery system or drug composition based on microalgae overcomes the disadvantages of short gastrointestinal retention time and insufficient efficacy in gastrointestinal tissues.

[0041] A fifth object of the present invention is to provide the use of the above-described pharmaceutical composition in gastrointestinal nutritional supplementation.

[0042] Preferably, the nutrients are components of the microalgae themselves, including proteins, unsaturated fatty acids, carotenoids, vitamins, and one or more of various trace elements such as iron, iodine, and zinc, or polysaccharides and other probiotics.

[0043] A sixth object of the present invention is to provide an oral formulation for drug delivery systems and for protection against damage caused by alcohol, acetic acid or infection, wherein the active ingredient of the oral formulation is an oral micro / nano drug delivery system or drug composition based on microalgae.

[0044] Preferably, the formulation is a liquid formulation or a solid formulation.

[0045] Preferably, the liquid formulation is an oral suspension.

[0046] Preferably, the solid dosage form is selected from at least one of tablets, powders, granules, and capsules.

[0047] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention is the first to prepare an oral micro-nano drug delivery system drug complex composed of natural microalgae and drugs, which overcomes the defect of traditional drugs that are difficult to stay in the gastrointestinal tract for a long time. After contact with gastric acid, it can adhere to the wound for a long time and achieve a longer retention time in the intestine. After application, it can maintain a high level of drug release and oral safety, and can achieve long-term retention and slow degradation in gastrointestinal tissues.

[0048] 2. This invention breaks through the limitations of the complex drug delivery process of traditional biological carriers. The dopamine-modified zinc oxide nanoparticles in this drug complex can adhere to the surface of microalgae without long-term incubation. A stable structure can be obtained with simple stirring, saving costs while maintaining the biological activity and structure of the microalgae.

[0049] 3. The drug complex of the present invention is an oral micro-nano-scale biological delivery system. Compared with other biological carriers that are concentrated in intestinal and intravenous administration, it is the first to realize the delivery of drugs that are retained in the stomach for a long time using biological carriers, and exert a long-term regulatory effect on gastrointestinal inflammation. The drug complex accelerates the release of dopamine-modified zinc oxide nanoparticles after contact with acid, realizing pH-triggered controlled release. At the same time, the drug complex is easily degraded by the digestive system, avoiding the toxic side effects caused by long-term retention in the body.

[0050] In this invention, the term "SP" refers to Spirulina.

[0051] In this invention, the term "ZnP" refers to zinc oxide nanoparticles modified with dopamine, a drug that protects against gastrointestinal damage.

[0052] In this invention, the term "SP@ZnP" refers to a drug complex of dopamine-modified zinc oxide nanoparticles adsorbed by spirulina. Attached Figure Description

[0053] Figure 1 Scanning electron micrographs of the drug complex (SP@ZnP), ZnP, and Spirulina (SP).

[0054] Figure 2 The absorption spectrum (left) and zeta potential spectrum (right) of the drug complex (SP@ZnP), ZnP, and Spirulina (SP).

[0055] Figure 3 This is an elemental distribution diagram of the drug complex (SP@ZnP).

[0056] Figure 4 The images show the in vivo fluorescence distribution of the drug complex loaded with the fluorescent probe FITC at different time points (A) and the fluorescence and quantitative distribution in the isolated gastrointestinal tract of mice at 3, 6, 12, and 24 hours after oral administration (BC).

[0057] Figure 5 Fluorescence micrograph of a gastrointestinal section 3 hours after the drug complex loaded with the fluorescent probe FITC was prepared.

[0058] Figure 6 Photographs (left) and statistical graphs (right) of the lesion area of ​​the drug complex that reduced alcohol-induced gastric bleeding and ulceration in an acute model, where * indicates p < 0.05; ** indicates p < 0.01; *** indicates p < 0.001.

[0059] Figure 7 HE staining image of a drug complex that reduces alcohol-induced gastric and duodenal damage in an acute model.

[0060] Figure 8 The effect of the drug complex on intestinal length shortening caused by oral bacterial infection and statistical graph (**, p value < 0.01).

[0061] Figure 9 Statistical graphs showing the reduction of intestinal and spleen bacterial load caused by oral bacterial infection by drug complexes (*, p < 0.05; **, p < 0.01; ***, p < 0.001).

[0062] Figure 10 A staining diagram to show how drug complexes reduce intestinal inflammation and damage caused by oral bacterial infections.

[0063] Figure 11 A diagram illustrating how drug complexes reduce intestinal barrier damage caused by oral bacterial infections.

[0064] Figure 12 This diagram illustrates how drugs can reduce gut microbiota imbalance caused by oral bacterial infections. Figure A shows the results of gut microbiota species richness analysis, Figure B shows the stacked diagram of relative abundance at the genus level, and Figure C shows the stacked diagram of relative abundance at the species level.

[0065] Figure 13 The graph shows the good biocompatibility of the drug complex as indicated by blood routine and blood biochemistry results (a: normal control; b: model group; c: SP; d: ZnP; e: SP@ZnP; *, p < 0.05; **, p < 0.01; ***, p < 0.001).

[0066] Figure 14 The H&E staining images of the major organs of mice in Example 5 of this invention show the good safety of the drug complex. Detailed Implementation

[0067] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the present invention is not limited to the following embodiments.

[0068] Unless otherwise specified, experimental methods in the following examples were performed under standard conditions or as recommended by the manufacturer. Reagents and instruments whose manufacturers are not specified are all commercially available products.

[0069] The spirulina used in the following examples is specifically Spirulina platensis.

[0070] Example 1. Synthesis of SP@ZnP Spirulina (SP) suspension cultured (Zygium saturate) under sterile conditions was collected. SP particles passing through a 40-mesh sieve were then collected through a 200-mesh sieve and washed three times with phosphate-buffered saline to remove residual culture medium. SP@ZnP was synthesized using a simple mixing method, as detailed below: 1. After culturing micron-sized Spirulina, the culture medium was removed, the precipitate was washed and collected to obtain fresh natural Spirulina, which was then resuspended to obtain a Spirulina suspension; 2. Weigh out zinc acetate and sodium hydroxide solids, dissolve them separately in ultrapure water, and then dilute them to obtain 20 mg / mL zinc acetate and 200 mg / mL sodium hydroxide solutions; 3. Dopamine-modified zinc oxide nanoparticles (ZnP) were obtained by adding 50 mg of dopamine hydrochloride powder to 10 mL of zinc acetate solution, dissolving it, then adding 500 μL of sodium hydroxide solution dropwise under vigorous stirring, heating and incubating at 50-100℃ for 0.5-2 hours, centrifuging to collect the precipitate, and resuspending it to obtain a drug suspension. 4. Based on the dry weight of Spirulina, mix the SP suspension and the dopamine-modified zinc oxide nanoparticle (ZnP) suspension at a mass ratio of 1:1, stir, centrifuge, and collect the precipitate. Wash 3-5 times to remove unloaded drug, obtaining a suspension with a final concentration of 10 mg / mL SP and 5 mg / mL ZnP. Allow ZnP to adhere to the SP surface. Incubation at room temperature for 2-12 hours will maintain stability. Collect the drug complex and take microscopic and scanning electron microscope images. The results are shown below. Figure 1 As shown, the drug complex is a structure composed of 3D spiral microalgae and dense granular ZnP nanoparticles.

[0071] Example 2. Validation of drug loading performance The absorption spectrum and zeta potential of the drug complex synthesized in Example 1 were detected using an absorption spectrometer and a zeta potential meter. Figure 2 The absorption spectrum of SP@ZnP showed a characteristic peak at 440 nm and a characteristic peak at 360 nm. The absorption spectrum of SP@ZnP exhibited characteristics of both SP (440 nm) and ZnP (360 nm); simultaneously, the Zeta potential of SP@ZnP changed. This demonstrates that ZnP was successfully loaded onto SP. The elemental distribution of the drug complex was detected using scanning electron microscopy and energy dispersive spectroscopy. Figure 3 The elemental distribution confirms that zinc (Zn) is concentrated in the SP@ZnP micro / nano system, visually demonstrating that ZnP was successfully loaded onto SP.

[0072] Example 3. Distribution in the body and gastrointestinal retention after oral administration Balb / c nude mice were fasted for 24 h, and then administered 200 µL of free FITC and SP@FITC (SP concentration 10 mg / mL) by gavage. Mice were anesthetized at 1, 3, 6, 12, and 24 hours post-gavage, and fluorescence images were captured using an in vivo imaging system (excitation wavelength: 445-490 nm, emission wavelength: 515-575 nm). Gastrointestinal tract sections were harvested at 3, 6, 12, and 24 hours post-gavage for further in vitro imaging. Figure 4 After imaging, mouse stomachs and intestines were harvested and prepared into frozen sections. Fluorescence accumulation was observed after DAPI staining. Figure 5 ).according to Figures 4-5 The results showed that free FITC, after oral administration, began to gradually diffuse and penetrate throughout the body after 3 hours, while SP@FITC fluorescence remained concentrated in the abdomen and maintained a high fluorescence intensity for 0-24 hours, with a longer gastrointestinal distribution time, which was conducive to the accumulation of drug concentration in gastrointestinal tissues; the gastrointestinal fluorescence images further demonstrated the retention effect of SP@ZnP in the stomach and intestines.

[0073] Example 4. Protective effect of drug complex against acute abdominal acetic acid-alcohol injury Eight-week-old female Balb / c mice were randomly divided into a normal control group, a model group (mice with an acute abdominal acetic acid-alcohol injury model), an SP group, a ZnP group, and an SP@ZnP group (n = 5 mice per group). After fasting for 24 hours, mice in each group were first given 10 mL / kg PBS to replenish gastric fluid. Subsequently, mice in the normal control group, SP group, ZnP group, and SP@ZnP group were administered 10 mL / kg PBS, 10 mL / kg SP (10 mg / mL), 10 mL / kg ZnP (5 mg / mL), and 10 mL / kg SP@ZnP (containing 10 mg / mL SP and 5 mg / mL ZnP) by gavage, respectively. One hour later, except for the normal control group, all other groups of mice were administered 100 μL of 3% glacial acetic acid and 200 μL of ethanol by gavage. Three hours after gavage, the animals were euthanized, and the stomachs were photographed and prepared for pathological sections and hematoxylin and eosin (HE) staining. The results showed that the gastric mucosa of mice in the alcohol group was significantly damaged, manifested as large-area ulceration and bleeding, while the damaged area in the treatment group was effectively reduced (P < 0.01). Figure 6 H&E staining results further indicated that SP@ZnP more effectively reduced gastric mucosal epithelial cell loss, edema, and inflammatory cells caused by acute acetic acid-alcohol injury. Figure 7 ).

[0074] Example 5. Protective effect of drug complexes against intestinal infectious damage Eight-week-old female Balb / c mice were randomly divided into a normal control group, an infection group (mouse intestinal infection model), an SP group, a ZnP group, and an SP@ZnP group (n = 5 mice per group). After fasting for 4 hours, all mice were given streptomycin 1 g / kg, followed immediately by resumption of water and food supply. After 24 hours, they were fasted again for 4 hours. Mice in the infection group, SP group, ZnP group, and SP@ZnP group were orally inoculated with 5 × 10⁻⁶ streptomycin. 7 CFU of Salmonella typhimurium ( Salmonella Typhimurium bacterial suspension. One hour later, the infection group, SP group, ZnP group, and SP@ZnP group were treated orally with various preparations: 10 mL / kg PBS, 10 mL / kg SP (10 mg / mL), 10 mL / kg ZnP (5 mg / mL), and 10 mL / kg SP-ZnP (containing 10 mg / mL SP and 5 mg / mL ZnP), respectively. The mice were sacrificed after 5 consecutive days of treatment.

[0075] Intestinal tissue samples from mice revealed that, compared to the normal group, the infected group had a significantly smaller cecum and a shorter colon, reflecting severe intestinal inflammation. The SP@ZnP treatment group showed a significant reduction in intestinal inflammation. Figure 8 After homogenizing and diluting different parts of the mouse intestine and spleen, the viable bacterial load in various tissues (cecum, small intestine, spleen, and colon contents) was quantified using the agar plate counting method. Figure 9 The protective effects of ZnP and SP@ZnP treatments on multiple tissues were observed. Intestinal pathological sections showed that SP@ZnP alleviated mucosal epithelial cell loss, goblet cell loss, and inflammatory cell infiltration. Immunohistochemical analysis using IL-1β polyclonal antibodies showed that multiple treatments, including SP, ZnP, and SP@ZnP, effectively alleviated infection-induced IL-1β upregulation, thereby effectively alleviating intestinal inflammation. Figure 10 ).

[0076] The gastrointestinal barrier function is crucial for protecting intestinal health and resisting microbial invasion, and is mainly composed of tight junctions of epithelial cells and mucins secreted by goblet cells. Immunological analysis using primary antibodies against ZO-1, Claudin-1, Occludin, and MUC-2 revealed a decrease in goblet cells, significantly reduced expression of MUC-2, ZO-1, and Claudin-1, and disordered Occludin arrangement in infected mice. Figure 11 Oral administration of SP@ZnP significantly restored the expression levels and structure of damaged barrier molecules, demonstrating a strong intestinal protective effect. This indicates that the drug delivery system of the present invention can effectively repair the physical and chemical barriers of the intestine damaged by infection.

[0077] To investigate the effects of different treatments on the gut microbiota, fresh fecal samples were aseptically collected from mice in each group. Total DNA was extracted using a bacterial genomic DNA extraction kit and then 16S sequencing was performed by a biotechnology company. The sequencing results were analyzed using the Chao1 index (reflecting species richness) and Shannon index (reflecting species diversity). The results showed that the ZnP treatment group partially restored infection-induced gut microbiota diversity. Further analysis at the genus and species level showed that the ZnP treatment group increased beneficial bacteria such as *Lactobacillus* and *Akermansia mucinidia*, and decreased harmful bacteria such as *Clostridium difficile*. Figure 12 These results collectively demonstrate that the system of the present invention, particularly the SP@ZnP group, exhibits the ability to reshape gut microbiota homeostasis and regulate gut microecological balance, which, in synergy with its anti-inflammatory and barrier repair effects, jointly exerts a powerful intestinal protective effect.

[0078] Example 6. Biosafety analysis of orally administered drug complex in mice Blood samples from mice in each treatment group of Example 5 were used for complete blood count, blood biochemistry, and histopathological examination of major organs. The results showed that compared with the normal control group, SP, ZnP, and SP@ZnP treatments could inhibit infection-induced upregulation of AST (aspartate aminotransferase) and ALT (alanine aminotransferase), but only the SP@ZnP group significantly restored infection-induced BUN expression levels (blood urea nitrogen); CR (creatinine) levels did not differ significantly among the groups, indicating that it has a unique advantage in improving infection-induced renal dysfunction. Figure 13 Apart from a slight upregulation of red blood cell (RBC) levels in each treatment group, there were no significant differences among the groups in white blood cell (WBC), neutrophil (NEU), lymphocyte (LYM), and monocyte (MON) levels. Figure 13 The results indicated that the complex did not cause significant hematological toxicity or abnormal inflammatory responses. Tissue sections from major organs of mice were prepared and stained with hematoxylin and eosin (H&E) before observation under a light microscope. The results showed that, except for the PBS group, histological examination of major organs such as the heart, liver, spleen, lungs, and kidneys revealed no abnormalities. Figure 14 The PBS group showed focal hepatocellular necrosis and a significantly increased ratio of red to white pulp in the spleen, indicating infection-related organ damage. These results demonstrate that the SP@ZnP oral delivery system has good in vivo biocompatibility.

[0079] The above embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. An oral micro / nano drug delivery system based on microalgae, characterized in that, include: Micron-sized spirulina, and nanoscale drug materials loaded on the surface of the spirulina; The pharmaceutical material is dopamine-modified zinc oxide nanoparticles.

2. The oral micro / nano drug delivery system based on microalgae according to claim 1, characterized in that, It also includes a solvent selected from at least one or more of sterile phosphate buffer, ultrapure water, distilled water, or physiological saline.

3. The oral micro / nano drug delivery system based on microalgae according to claim 1, characterized in that, The mass ratio of spirulina to pharmaceutical material is 1:0.1-1:1, and the mass ratio of zinc oxide nanoparticles to dopamine in the zinc oxide nanoparticles is 1:0.1-1:

1.

4. A method for preparing an oral micro / nano drug delivery system based on microalgae as described in any one of claims 1-3, characterized in that, Includes the following steps: After culturing micron-sized Spirulina, the culture medium was removed, the precipitate was washed and collected to obtain fresh natural Spirulina, which was then resuspended to obtain a Spirulina suspension. Weigh out zinc acetate and sodium hydroxide solids, dissolve them separately in ultrapure water, and then dilute them to obtain 10-20 mg / mL zinc acetate and 10-200 mg / mL sodium hydroxide solutions; add 50 mg of dopamine hydrochloride to 20 mL of zinc acetate solution beforehand, add 500 μL of sodium hydroxide solution dropwise under vigorous stirring, heat and incubate, centrifuge, collect the precipitate and resuspend to obtain a drug suspension; Based on the dry weight of Spirulina, the Spirulina is resuspended and mixed with the drug suspension at a mass ratio of 1:0.1-1:

1. The mixture is incubated at room temperature, the precipitate is collected by centrifugation, washed, and then post-processed to obtain a suspension or solid powder of the drug complex.

5. The preparation method according to claim 4, characterized in that, The post-processing involves freeze-drying, vacuum drying, or resuspending in a solvent to obtain a solid powder or suspension formulation of the oral micro / nano drug delivery system.

6. The use of the oral micro / nano drug delivery system based on microalgae according to any one of claims 1-3, characterized in that, include: (1) Preparation of protective drugs related to abdominal diseases; (2) Preparation of gastrointestinal regulating drugs.

7. The use according to claim 6, characterized in that, The abdominal disease mentioned is any one of alcohol injury, acetic acid injury, or Salmonella infection injury.

8. The use according to claim 6, characterized in that, The gastrointestinal regulating drugs include any one of the following: gastrointestinal nutritional supplements, drugs to reduce intestinal inflammation, drugs to repair the intestinal mucosal barrier, or drugs to regulate intestinal flora.

9. An oral preparation, characterized in that, The active ingredient of the oral formulation includes the microalgae-based oral micro / nano drug delivery system as described in any one of claims 1-3, and at least one pharmaceutically acceptable additive.

10. The oral formulation according to claim 1, characterized in that, The formulation may be a liquid or a solid formulation.

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