Shewanella-cerium oxide nano-cluster compound, preparation method thereof and application of shewanella-cerium oxide nano-cluster compound in preparation of anti-radiation drugs

Abstract

The invention provides a shewanella-cerium oxide nano-cluster compound, a preparation method thereof and application of the shewanella-cerium oxide nano-cluster compound in preparation of anti-radiation drugs, and belongs to the technical field of anti-radiation materials. According to the invention, a shewanella bioelectronic interface is combined with a CeO2 semiconductor nanomaterial, and when CeO2 forms an interface with shewanella and other electroactive bacteria with EET capability, metal-carrier interaction (MSI) can critically regulate and control an electronic structure of a catalytic active site. The shewanella-cerium oxide nano-cluster compound disclosed by the invention can be used for improving ion conversion between Ce < 3 + > and Ce < 4 + >, so that free radicals brought by radiation damage are reduced, and the damage of radiation to an organism is reduced. Besides, the shewanella-cerium oxide nano-cluster compound disclosed by the invention has excellent antioxidant activity, can regulate and control the intestinal microenvironment while efficiently removing various free radicals, has obvious improvement on intestinal protection after radiation irradiation, and can improve the survival rate of biological organisms.

Description

Technical Field

[0001] This invention relates to the field of anti-radiation materials technology, specifically to a Shewanella-cerium oxide nanocluster composite, its preparation method, and its application in the preparation of anti-radiation drugs. Background Technology

[0002] High-dose ionizing radiation exposure is a critical biosafety risk source in fields such as nuclear accidents, radiotherapy, and space exploration. The pathological mechanisms of radiation damage are closely related to cascade damage mediated by reactive oxygen species (ROS). Upon exposure to ionizing radiation, biological tissues immediately generate ROS clusters through radiochemical reactions, including superoxide anions (•O2). - Radiation-induced oxidative stresses (ROS) and hydroxyl radicals (•OH) can cause oxidative damage to vital systems such as the hematopoietic system, gastrointestinal epithelium, and neurovascular networks. Furthermore, radiation-induced gut microbiota dysbiosis can exacerbate systemic inflammatory responses through the gut-organ axis, further complicating the body's recovery process.

[0003] Traditional antioxidants (such as amifostine, cerium oxide, and tea polyphenols) have certain effects, but their clinical applications are significantly limited: they cannot simultaneously and efficiently scavenge multiple ROS and regulate the gut microenvironment, thus restricting their clinical translation in the field of radiation protection. Therefore, there is an urgent need to develop innovative materials that can more effectively address the above challenges.

[0004] Cerium dioxide (CeO2) nanomaterials are unique due to their CeO2 content. 3+ / Ce 4+ CeO2 nanozymes exhibit excellent ROS scavenging capabilities due to their redox cycle characteristics, attracting widespread attention. However, despite their promising prospects, CeO2 nanozymes still face challenges in terms of catalytic selectivity. For example, their disproportionation efficiencies for different ROS, such as hydrogen peroxide (H2O2) and superoxide radicals, vary significantly. Furthermore, their stability under physiological conditions, related to surface oxygen vacancies, is also a prominent issue, making them unsuitable for radiation protection in vivo. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a Shewanella-cerium oxide nanocluster complex, its preparation method, and its application in the preparation of anti-radiation drugs. The Shewanella-cerium oxide nanocluster complex provided by this invention has good matrix radiation protection effect, and its intestinal protection effect is significantly enhanced after radiation irradiation.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: The present invention provides a Shewanella-cerium oxide nanocluster composite, comprising Shewanella and CeO2 nanoclusters distributed on the surface of the Shewanella membrane.

[0007] Preferably, the Shewanella-cerium oxide nanoclusters composite has a length of 1.5~2 μm and a diameter of 200~400 nm.

[0008] Preferably, the Shewanella includes Shewanella oneidensis MR-1.

[0009] This invention provides a method for preparing the above-mentioned Shewanella-cerium oxide nanoclusters composite, comprising the following steps: The Shewanella suspension was centrifuged, and the resulting cell precipitate was resuspended in water to obtain a Shewanella cell dispersion. The Shewanella cell dispersion was mixed with a cerium source solution, and an alkali solution was added to adjust the pH to 10.0. A hydrolysis-oxidation reaction was carried out, and after precipitation, the Shewanella-cerium oxide nanoclusters complex was obtained.

[0010] Preferably, the bacterial density of the Shewanella suspension is OD. 600 =0.8~1; The centrifugation process is carried out at a temperature of 4-8°C, a speed of 8000-10000×g, and a single centrifugation time of 5-10 min; the centrifugation process is carried out 3-4 times.

[0011] Preferably, the concentration of the Shewanella cell dispersion is 8-10 mg / mL; The concentration of the cerium source solution is 150~200 mM; The volume ratio of the Shewanella cell dispersion to the cerium source solution is 10:0.1~1.

[0012] Preferably, after the Shewanella cell dispersion is mixed with the cerium source solution, it is further subjected to magnetic stirring homogenization, wherein the magnetic stirring homogenization rate is 500~800 rpm and the time is 10~30 min.

[0013] Preferably, the hydrolysis-oxidation reaction is carried out at a temperature of 23~27℃ for 6~8 hours.

[0014] This invention provides the application of the above-mentioned Shewanella-cerium oxide nanoclusters complex in the preparation of anti-radiation drugs.

[0015] The present invention provides a radiation protection formulation comprising the above-mentioned Shewanella-cerium oxide nanoclusters complex.

[0016] This invention provides a Shewanella-cerium oxide nanocluster composite, comprising Shewanella bacteria and CeO2 nanoclusters distributed on the surface of the Shewanella bacterial membrane. This invention utilizes the extracellular electron transport (EET) system of Shewanella oneidensis MR-1, an electroactive bacterium possessing unique transmembrane redox capabilities. Its Mtr (metal-reducing trigonelline) respiratory chain achieves efficient electron transport from intracellular NADH to extracellular receptors via an electron shuttle mechanism mediated by c-type cytochrome (MtrC / OmcA) and flavin. This invention combines such a bioelectronic interface with CeO2 semiconductor nanomaterials, providing an innovative pathway to enhance the dynamic catalytic cycle of nanozymes. Specifically, in CeO2, cerium atoms exhibit a face-centered cubic close-packed structure. 4+ The ions and oxygen ions form a fluorite-type crystal arrangement. Notably, the CeO2 surface has a high density of oxygen vacancies (Vo), which originate from Ce. 3+ With Ce 4+ Reversible redox transitions between oxidation states. When CeO2 forms an interface with electroactive bacteria such as Shewanella, which possess EET capabilities, metal-support interaction (MSI) can crucially modulate the electronic structure of catalytically active sites. This interfacial electron redistribution optimizes the adsorption / desorption balance of hydroxyl radicals (•OH), thereby enhancing the material's free radical scavenging ability.

[0017] The Shewanella-cerium oxide nanoclusters complex provided by this invention can enhance Ce 3+ Ce 4+ The ion conversion between them reduces free radicals caused by radiation damage, thereby mitigating radiation-induced damage to the body. Furthermore, the Shewanella-cerium oxide nanocluster complex of this invention exhibits excellent antioxidant activity, effectively scavenging various free radicals while regulating the intestinal microenvironment. It provides intestinal protection after radiation irradiation, stemming from the Shewanella-cerium oxide nanocluster complex of this invention promoting Ce2+ ion exchange in the intestinal tract. 3+ / Ce 4+ The reversible cycle enables continuous SOD / CAT-like catalytic scavenging, which can effectively remove various reactive oxygen / nitrogen free radicals induced by radiation, thereby reducing the oxidative stress level of epithelial cells and improving the survival rate of organisms.

[0018] This invention provides a method for preparing the above-mentioned Shewanella-cerium oxide nanoclusters complex. This method is simple to operate, low in cost, and suitable for mass production. Attached Figure Description

[0019] Figure 1 The XRD patterns of SW@cerium oxide obtained in Examples 1-4 are shown below. Figure 2TEM images of SW and SW@cerium oxide from Example 1; Figure 3 The Zeta potentials of SW and SW@cerium oxide obtained in Examples 1-4; Figure 4 The activity evaluation results for SW and SW@CeO2 are shown. Figure 5 The ability of SW@cerium oxide obtained in Examples 1-4 to scavenge hydroxyl radicals; Figure 6 Electrochemical impedance spectroscopy (EIC) spectra of EcN, SW, cerium oxide, and SW@cerium oxide. Figure 7 XPS spectra of CeO2 and SW@CeO2; Figure 8 The intestinal MDA content 24 hours after different treatments; Figure 9 The intestinal SOD content 24 hours after different treatments; Figure 10 The intestinal GPX content 24 hours after different treatments; Figure 11 H&E stained sections of mouse intestine; Figure 12 Survival curves after irradiation for different treatment groups. Detailed Implementation

[0020] The present invention provides a Shewanella-cerium oxide nanocluster composite, comprising Shewanella and CeO2 nanoclusters distributed on the surface of the Shewanella membrane.

[0021] In this invention, the Shewanella bacteria in the Shewanella-cerium oxide nanoclusters composite are live bacteria. Preferably, the Shewanella bacteria in this invention include *Shewanella oneidensis* MR-1. The Shewanella bacteria in this invention are commercially available.

[0022] In this invention, the length of the Shewanella-cerium oxide nanoclusters composite is preferably 1.5~2 μm, more preferably 1.6~1.8 μm; the diameter is preferably 200~400 nm, more preferably 300 nm.

[0023] This invention provides a method for preparing the above-mentioned Shewanella-cerium oxide nanoclusters composite, comprising the following steps: The Shewanella suspension was centrifuged, and the resulting cell precipitate was resuspended in water to obtain a Shewanella cell dispersion. The Shewanella cell dispersion was mixed with a cerium source solution, and an alkali solution was added to adjust the pH to 10.0. A hydrolysis-oxidation reaction was carried out, and after precipitation, the Shewanella-cerium oxide nanoclusters complex was obtained.

[0024] This invention involves centrifuging a Shewanella suspension, then resuspending the resulting cell precipitate in water to obtain a Shewanella cell dispersion. In this invention, the preferred bacterial density of the Shewanella suspension is OD0.05. 600 =0.8~1, more preferably 0.9~1; the centrifugation temperature is preferably 4~8℃, the centrifugation rate is preferably 8000~10000×g, and the single centrifugation time is preferably 5~10min; the number of centrifugation treatments is preferably 3~4 times; after a single centrifugation treatment, the resulting precipitate is preferably dispersed in pre-cooled deionized water. In this invention, the concentration of the Shewanella cell dispersion is preferably 8~10 mg / mL, more preferably 9~10 mg / mL.

[0025] The *Shewanella* cell dispersion is mixed with a cerium source solution, and the pH is adjusted to 10.0 by adding alkali. A hydrolysis-oxidation reaction is then carried out, and after precipitation, a *Shewanella*-cerium oxide nanocluster complex is obtained. In this invention, the cerium source is preferably Ce(NO3)3·6H2O, and the solvent is preferably water; the concentration of the cerium source solution is preferably 150-200 mM, more preferably 160-180 mM. In this invention, the volume ratio of the *Shewanella* cell dispersion to the cerium source solution is preferably 10:0.1-1, more preferably 10:0.2-0.8, and even more preferably 10:0.5. After mixing the *Shewanella* cell dispersion and the cerium source solution, this invention preferably performs magnetic stirring homogenization. The magnetic stirring homogenization rate is preferably 500-800 rpm, and the time is preferably 10-30 min, more preferably 10-20 min.

[0026] In this invention, the alkaline solution is preferably a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is preferably 1M. In this invention, the temperature of the hydrolysis-oxidation reaction is preferably 23~27℃, more preferably 25℃, and the time is preferably 6~8h, more preferably 6~7h. In this invention, during the hydrolysis-oxidation reaction, the Ce(OH)3 generated by the added alkaline solution undergoes heterogeneous nucleation on the surface / extracellular matrix of Shewanella cells and is oxidized to CeO2 nanoclusters under the action of dissolved oxygen. The resulting cerium oxide surface can form Ce... 3+ / Ce 4+ Coexisting redox pairs.

[0027] Following the hydrolysis-oxidation reaction, the present invention preferably performs post-treatment on the obtained hydrolysis-oxidation reaction product, the post-treatment preferably including the following steps: The hydrolysis-oxidation reaction product was centrifuged, the precipitate was collected, and the precipitate was washed and freeze-dried.

[0028] In this invention, the centrifugation temperature is preferably 4°C, the centrifugation rate is preferably 12,000 × g, and the centrifugation time is preferably 15 min. In this invention, the washing is preferably performed with deionized water, and the washing is preferably performed three times. This washing removes unreacted ions. After washing, the resulting product is resuspended in deionized water.

[0029] In this invention, the freeze-drying preferably includes pre-freezing and vacuum freeze-drying. The pre-freezing temperature is preferably -80°C and the time is preferably 12 hours. The vacuum freeze-drying pressure is preferably 0.1 mbar and the time is preferably 24 hours.

[0030] This invention provides the application of the above-mentioned Shewanella-cerium oxide nanoclusters complex in the preparation of anti-radiation drugs. The Shewanella-cerium oxide nanoclusters complex provided by this invention has good matrix radiation protection effect, and its intestinal protection effect is significantly enhanced after radiation irradiation.

[0031] This invention provides a radiation protection formulation comprising the above-mentioned Shewanella-cerium oxide nanoclusters complex. In this invention, the radiation protection formulation is preferably an oral preparation, and the dosage form is preferably a powder or suspension.

[0032] The following examples illustrate the Shewanella-cerium oxide nanoclusters, their preparation method, and their application in the preparation of anti-radiation drugs provided by this invention. However, these examples should not be construed as limiting the scope of protection of this invention.

[0033] In the following examples, Shewanella is... Shewanella oneidensis MR-1 is from Beina Biotechnology Co., Ltd., catalog number BNCC387340; Ce(NO3)3·6H2O is from Maclean Bioreactor Co., Ltd.; NaOH is from Maclean Bioreactor Co., Ltd.

[0034] Example 1 The preparation method of Shewanella-cerium oxide nanoclusters comprises the following steps: (1) Take 10 mL of Shewanella (SW) suspension with OD600=1 and centrifuge at 8,000×g for 5 minutes at 4°C using an Eppendorf 5810R centrifuge. After discarding the supernatant, resuspend the cell pellet in pre-cooled deionized water and perform three additional centrifugation-wash cycles to remove residual culture medium. Finally, the pellet is uniformly dispersed in 10 mL of deionized water to obtain Shewanella cell dispersion, which is then packaged into a 50 mL Erlenmeyer flask.

[0035] (2) 500 μL of 200 mM Ce(NO3)3·6H2O solution was added to the Shewanella cell dispersion, and the mixture was magnetically stirred for 10 minutes at 500 rpm to homogenize it. Then, 1 M sodium hydroxide solution was gradually added, and the pH was monitored in real time to 10.0 ± 0.1 using a pH meter. The reaction system was kept open at 25 ± 2 °C and stirred continuously for 6 hours. The resulting mixture was transferred to a 15 mL centrifuge tube and centrifuged at 12,000 × g for 15 minutes at 4 °C to precipitate. The collected precipitate was washed three times with deionized water to remove unreacted ions. The final product was resuspended in 2 mL of deionized water, transferred to a lyophilization tube, pre-frozen at -80 °C for 12 hours, and then lyophilized under 0.1 mbar vacuum for 24 hours to obtain the Shewanella-cerium oxide nanocluster complex, denoted as SW@cerium oxide.

[0036] Example 2 Compared with Example 1, the difference is that 100 μL of 200 mM Ce(NO3)3·6H2O solution is added in step (2).

[0037] Example 3 Compared with Example 1, the difference is that 250 μL of 200 mM Ce(NO3)3·6H2O solution is added in step (2).

[0038] Example 4 Compared with Example 1, the difference is that 1000 μL of 200 mM Ce(NO3)3·6H2O solution is added in step (2).

[0039] Structural characterization (1) The XRD patterns of SW@cerium oxide obtained in Examples 1-4 are as follows: Figure 1 As shown, Figure 1 The spectral lines at the bottom are labeled with a reference spectrum of cerium oxide (JCPDS card number 43-1002). (By...) Figure 1 It can be seen that the nanomaterials synthesized by Shewanella with different amounts of added cerium ions are completely consistent with the standard spectrum of cerium oxide, indicating that the present invention has successfully synthesized nanomaterials.

[0040] (2) TEM images of SW and SW@cerium oxide in Example 1 (scale bar: 200 nm) are shown below. Figure 2 As shown, by Figure 2 It can be seen that, compared with the exposed Shewanella group, CeO2 in the SW@CeO2 group grew a protective layer on the surface of Shewanella.

[0041] (3) The Zeta potentials of SW and SW@cerium oxide obtained in Examples 1-4 are as follows: Figure 3 As shown, by Figure 3It can be seen that as the amount of cerium ions added increases, the potential of the Shewanella composite nanomaterial changes from negative to positive.

[0042] Performance testing (1) Activity evaluation of SW@CeO2 10 mg of lyophilized SW@CeO2 and SW obtained in Example 1 were dissolved in culture medium, and the mixed liquid was then inoculated into tryptone soybean agar medium and cultured for 24 h for bacterial counting. The results are as follows. Figure 4 As shown. By Figure 4 It can be seen that the activity of Shewanella modified with cerium dioxide nanozymes is not affected.

[0043] (2) Hydroxyl radical scavenging experiment The test method was as follows: The test material with a final concentration of 100 mg / mL was mixed with hydrogen peroxide with a final concentration of 5 mM in 5 mL of water. After reacting at room temperature for 30 minutes, the temperature was increased, the reaction solution was centrifuged to remove the material, and the solution was resuspended in deionized water and tested according to the instructions of the hydroxyl radical scavenging kit (Solepro, BC1325).

[0044] The ability of SW@cerium oxide obtained in Examples 1-4 to scavenge hydroxyl radicals is as follows: Figure 5 As shown. By Figure 5 It can be seen that the product exhibits the strongest free radical scavenging ability when the cerium ion addition is 500 μL and 1000 μL. Among products with the same free radical scavenging ability, adhering to the principle of raw material conservation, a 500 μL Ce ion addition system was ultimately selected, and subsequent experiments were conducted using SW@cerium oxide from Example 1.

[0045] (3) Using Escherichia coli (EcN) as a reference material, the electrochemical impedance spectroscopy (EICS) spectra of EcN, SW, cerium oxide, and SW@cerium oxide are shown below. Figure 6 As shown. By Figure 6 It can be seen that Shewanella's enhanced electron transfer ability can reduce the impedance value of the product, making it easier to scavenge hydroxyl radicals.

[0046] Impedance fitting was performed on the above materials using the following method: The sample to be tested was constructed as an electrochemical system. After the system stabilized at a set DC bias potential or open circuit potential (OCP), a small AC perturbation voltage / current was applied, and the frequency was scanned to obtain impedance spectrum data. The AC perturbation amplitude was 5~10 mV (rms), and the scanning frequency range was 10... 5 ~10 -2 Hz (can be adjusted according to the system). Record the complex impedance data at each frequency point. The impedance data are then fitted using ZView software.

[0047] The results are shown in Table 1.

[0048] Table 1 Impedance fitting results of different nanomaterials

[0049] The electrochemical results show that the impedance is the lowest among all groups because the SW@cerium oxide obtained in this invention has a high electron transfer efficiency.

[0050] (4) XPS spectroscopy was performed on CeO2 and SW@CeO2 to characterize the Ce content in the products. 3+ / Ce 4+ The valence composition and relative content are as follows: Figure 7 As shown. By Figure 7 It can be seen that, compared with CeO2, Ce in SW@CeO2 is... 3+ The relative content increased from 13.4% to 24.4%. This result indicates that the introduction of Shewanella helps promote Ce... 3+ / Ce 4+ Electron transfer and reversible conversion between them enhance the redox cycle capacity of the material, thereby strengthening its ability to scavenge oxidative stress-related reactive free radicals.

[0051] (5) To evaluate the protective effect of this product against radiation-induced intestinal damage, this invention uses irradiated mouse intestinal tissue as the subject to detect and compare typical oxidative stress-related indicators. Based on existing CeO2 nanomaterials, the radiation effects of the two on organisms are compared. The mice were pretreated as follows: the product was administered to the mice by gavage. First, the mice were fasted for 4-8 hours, and then gastric acid inhibitor (200 μL, phosphate buffer, containing 1.3% sodium bicarbonate solution and 3.6% magnesium hydroxide) was injected into the mice by gavage 0.5 h in advance. Finally, SW@CeO2 (100 mg / mL) was injected. Mice pretreated with SW@CeO2 (100 mg / mL) were irradiated with X-rays at a dose of 10 Gy according to the X-ray machine operation procedure. They were then housed in incubation cages for 24 hours. Subsequently, intestinal tissue from the mice was collected and analyzed according to the instructions of the following kits: malondialdehyde (MDA) (Solepro, BC6415), superoxide dismutase (SOD) (Solepro, BC5165), and glutathione peroxidase (GPX) kits (Solepro, BC1195). The experimental results are as follows: Figures 8-10 As shown. Among them, Figure 8 The intestinal MDA content 24 hours after different treatments. Figure 9 The intestinal SOD content 24 hours after different treatments, Figure 10The intestinal GPX content was measured 24 hours after different treatments. Results showed that, compared with the irradiation-only group, the SW@CeO2 treatment group exhibited significantly lower levels of malondialdehyde (MDA), a lipid peroxidation product, in its intestinal tissue, while significantly higher activities of enzymes related to the antioxidant defense system, particularly superoxide dismutase (SOD) and glutathione peroxidase (GPX). These results indicate that SW@CeO2 can effectively inhibit radiation-induced lipid peroxidation, enhance the clearance capacity of the body's endogenous antioxidant enzyme system, thereby reducing radiation-induced oxidative stress and alleviating intestinal tissue damage, demonstrating a good radiation protection effect.

[0052] After the above irradiation treatment, mouse intestinal tissue was harvested, fixed, paraffin-embedded, and sectioned. Histological morphology was observed using H&E staining. The results are as follows: Figure 11 As shown. By Figure 11 As can be seen, the intestinal mucosal structure of mice in the blank control group was significantly damaged after X-ray irradiation, manifested as incomplete villus structure, epithelial cell shedding, reduced number and disordered morphology of intestinal crypts, and typical characteristics of radiation-induced intestinal injury such as local mucosal edema and inflammatory cell infiltration. In contrast, the intestinal tissue structure of mice treated with SW@CeO2 was relatively intact, the villus and crypt morphology were well preserved, the degree of crypt damage was significantly reduced, mucosal continuity was improved, and inflammatory response and tissue edema were also reduced. This indicates that SW@CeO2 can significantly alleviate radiation-induced intestinal histological damage and has a certain protective effect on the intestine.

[0053] Survival curves after irradiation in different treatment groups are as follows: Figure 12 As shown, by Figure 12 It can be seen that the SW@cerium oxide of the present invention has a significant improvement in the protection of the intestines after radiation irradiation. In addition, SW@cerium oxide can improve the survival rate of organisms by reducing the side effects of radiation.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A Shewanella-cerium oxide nanocluster complex, characterized in that, The Shewanella and CeO2 nanoclusters distributed on the membrane surface of the Shewanella.

2. The Shewanella-cerium oxide nanocluster complex of claim 1, wherein, The length of the Shewanella-CeO2 nanocluster complex is 1.5-2 μm, and the diameter is 200-400 nm.

3. The Shewanella-cerium oxide nanocluster complex of claim 1, wherein, The Shewanella include Shewanella oneidensis MR-1.

4. The method for preparing the Shewanella-cerium oxide nanocluster complex according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: The Shewanella cell dispersion is obtained by centrifuging the Shewanella suspension and resuspending the obtained cell precipitate in water. The Shewanella cell dispersion is mixed with a cerium source solution, an alkali solution is added to adjust the pH value to 10.0, and a hydrolysis-oxidation reaction is performed, and the Shewanella-CeO2 nanocluster complex is obtained after precipitation.

5. The preparation method according to claim 4, characterized in that, The bacterial density of the Shewanella suspension is OD 600 = 0.8-1; The centrifugation is performed at a temperature of 4-8℃, a speed of 8000-10000×g, and a single centrifugation time of 5-10 min, and the centrifugation is performed 3-4 times.

6. The preparation method according to claim 4, characterized in that, The concentration of the Shewanella cell dispersion is 8-10 mg / mL. The concentration of the cerium source solution is 150-200 mM. The volume ratio of the Shewanella cell dispersion to the cerium source solution is 10:0.1-1.

7. The preparation method according to claim 4, characterized in that, After the Shewanella cell dispersion and the cerium source solution are mixed, magnetic stirring homogenization is further performed, the speed of the magnetic stirring homogenization is 500-800 rpm, and the time is 10-30 min.

8. The preparation method according to claim 4, characterized in that, The temperature of the hydrolysis-oxidation reaction is 23-27℃, and the time is 6-8 h.

9. Use of the Shewanella-CeO2 nanocluster complex of any one of claims 1-3 or the Shewanella-CeO2 nanocluster complex prepared by the preparation method of any one of claims 4-8 in the preparation of an anti-radiation drug.

10. A radioprotective preparation, characterized by, The Shewanella-CeO2 nanocluster complex of any one of claims 1-3 or the Shewanella-CeO2 nanocluster complex prepared by the preparation method of any one of claims 4-8.

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