1.The Role and Mechanism of Circadian Rhythm Regulation in Skin Tissue Regeneration
Ya-Qi ZHAO ; Lin-Lin ZHANG ; Xiao-Meng MA ; Zhen-Kai JIN ; Kun LI ; Min WANG
Progress in Biochemistry and Biophysics 2025;52(5):1165-1178
Circadian rhythm is an endogenous biological clock mechanism that enables organisms to adapt to the earth’s alternation of day and night. It plays a fundamental role in regulating physiological functions and behavioral patterns, such as sleep, feeding, hormone levels and body temperature. By aligning these processes with environmental changes, circadian rhythm plays a pivotal role in maintaining homeostasis and promoting optimal health. However, modern lifestyles, characterized by irregular work schedules and pervasive exposure to artificial light, have disrupted these rhythms for many individuals. Such disruptions have been linked to a variety of health problems, including sleep disorders, metabolic syndromes, cardiovascular diseases, and immune dysfunction, underscoring the critical role of circadian rhythm in human health. Among the numerous systems influenced by circadian rhythm, the skin—a multifunctional organ and the largest by surface area—is particularly noteworthy. As the body’s first line of defense against environmental insults such as UV radiation, pollutants, and pathogens, the skin is highly affected by changes in circadian rhythm. Circadian rhythm regulates multiple skin-related processes, including cyclic changes in cell proliferation, differentiation, and apoptosis, as well as DNA repair mechanisms and antioxidant defenses. For instance, studies have shown that keratinocyte proliferation peaks during the night, coinciding with reduced environmental stress, while DNA repair mechanisms are most active during the day to counteract UV-induced damage. This temporal coordination highlights the critical role of circadian rhythms in preserving skin integrity and function. Beyond maintaining homeostasis, circadian rhythm is also pivotal in the skin’s repair and regeneration processes following injury. Skin regeneration is a complex, multi-stage process involving hemostasis, inflammation, proliferation, and remodeling, all of which are influenced by circadian regulation. Key cellular activities, such as fibroblast migration, keratinocyte activation, and extracellular matrix remodeling, are modulated by the circadian clock, ensuring that repair processes occur with optimal efficiency. Additionally, circadian rhythm regulates the secretion of cytokines and growth factors, which are critical for coordinating cellular communication and orchestrating tissue regeneration. Disruptions to these rhythms can impair the repair process, leading to delayed wound healing, increased scarring, or chronic inflammatory conditions. The aim of this review is to synthesize recent information on the interactions between circadian rhythms and skin physiology, with a particular focus on skin tissue repair and regeneration. Molecular mechanisms of circadian regulation in skin cells, including the role of core clock genes such as Clock, Bmal1, Per and Cry. These genes control the expression of downstream effectors involved in cell cycle regulation, DNA repair, oxidative stress response and inflammatory pathways. By understanding how these mechanisms operate in healthy and diseased states, we can discover new insights into the temporal dynamics of skin regeneration. In addition, by exploring the therapeutic potential of circadian biology in enhancing skin repair and regeneration, strategies such as topical medications that can be applied in a time-limited manner, phototherapy that is synchronized with circadian rhythms, and pharmacological modulation of clock genes are expected to optimize clinical outcomes. Interventions based on the skin’s natural rhythms can provide a personalized and efficient approach to promote skin regeneration and recovery. This review not only introduces the important role of circadian rhythms in skin biology, but also provides a new idea for future innovative therapies and regenerative medicine based on circadian rhythms.
2.Research on the influence of meteorological factors on the incidence of foodborne diseases
Xuepei ZHANG ; Aiying TENG ; Shanshan WANG ; Xuehua ZHANG ; Min LIU ; Yanhua LIU ; Li ZHENG ; Wei MA
Journal of Public Health and Preventive Medicine 2024;35(1):45-48
Objective To explore the correlation between the incidence of foodborne diseases and meteorological factors in Jinan, and to provide targeted measures for the prevention and control of foodborne diseases. Methods Data from the reporting systems of two sentinel hospitals for active surveillance of foodborne diseases from 2013 to 2021 in Jinan were collected. The meteorological data in the same period in Jinan were also collected. The generalized additive model was used to explore the nonlinear relationship between meteorological factors and the incidence of foodborne diseases, and threshold function analysis was use to perform subsection regression. Results The incidence of foodborne diseases was positively correlated with daily average temperature (rs=0.23), relative humidity (rs=0.05), and daily average wind speed (rs=0.01), and negatively correlated with daily average air pressure (rs=-0.19). Based on the GAM results and segmented regression analysis of meteorological factors, it was found that when the daily average temperature was below or above the threshold of 24.63°C, for every 1°C increase in daily average temperature, the incidence of foodborne diseases correspondingly increased by 0.04% and 0.18%. When the daily average wind speed was above the threshold of 2.26 m/s, the incidence of foodborne diseases decreased by 0.36% for every 1 m/s increase in the daily average wind speed. Conclusion Nine years of observation and data analysis have shown that meteorological factors such as daily average temperature, relative humidity, air pressure, and wind speed are related to the incidence of foodborne diseases. These findings suggest that meteorological factors may be important factors leading to foodborne diseases, which provides an important scientific basis for formulating effective prevention and control measures.
3.Effects of Yiqi tongmai formula on atherosclerosis in ApoE-/- mice and its mechanism
Quanna REN ; Yuhan CHEN ; Kun WANG ; Ming MA ; Yanhua YANG ; Yu ZHANG ; Xu ZHAO
China Pharmacy 2024;35(18):2232-2237
OBJECTIVE To investigate the effects of Yiqi tongmai formula on atherosclerosis (AS) in ApoE-/- mice and its mechanism. METHODS Forty ApoE-/- mice were randomly divided into model group, positive control group [atorvastatin calcium, 2.6 mg/(kg·d)], and low-dose, medium-dose and high-dose groups of Yiqi tongmai formula [0.46, 0.91, 1.82 g/(kg·d), by raw material], with 8 mice in each group. Eight C57BL/6J mice were selected as the normal group. Except for the normal group, the other groups were given a high-lipid diet and relevant drug or normal saline intragastrically, once a day, for 12 consecutive weeks. After the last medication, the serum levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) as well as the contents of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and monocyte chemoattractant protein-1 (MCP-1) were measured in mice. The proportion of aortic plaque area in each group of mice was detected and calculated, and the pathological morphological changes of the aortic sinus were observed; the protein phosphorylation levels of aortic phosphoinositide 3-kinase (PI3K), protein kinase B (aka Akt) and mammalian target of rapamycin (mTOR) were examined. RESULTS Compared with the model group, the serum levels of TC, TG and LDL-C and the contents of TNF-α, IL-1β and MCP-1 (including low-dose group) were decreased significantly in medium-dose and high-dose groups of Yiqi tongmai formula, while the content of HDL-C in high-dose group was increased significantly (P<0.05 or P<0.01); aortic plaques of the mice were reduced in Yiqi tongmai formula groups to different extents, and pathological changes such as lipid deposition and inflammatory cell infiltration were relieved to different extents; the proportion of aortic plaque area, the protein phosphorylation levels of PI3K, Akt and mTOR in aortic tissue were significantly reduced in medium-dose and high-dose groups of Yiqi tongmai formula (P<0.05 or P<0.01). CONCLUSIONS Yiqi tongmai formula can improve lipid metabolism, reduce inflammatory response, and delay plaque development in AS mice. Its effect may be related to the inhibition of PI3K/Akt/mTOR signaling pathway activation.
4.Application of seasonal ARIMA model in predicting the monthly incidence of foodborne diseases
Xuepei ZHANG ; Lin ZHOU ; Min LIU ; Aiying TENG ; Yanhua LI ; Wei MA
Journal of Public Health and Preventive Medicine 2024;35(5):6-9
Objectives To explore the trend characteristics of foodborne diseases in Jinan City and apply the seasonal autoregressive integrated moving average model (SARIMA) for prediction. Methods The incidence data of foodborne diseases from two active monitoring sentinel hospitals in Jinan City from 2014 to 2020 were collected to establish a time series. The SARIMA model was used to fit the incidence situation. The numbers of cases in 2021 were compared with the predicted values to validate the model and evaluate the predictive effect. Results The SARIMA (2, 0, 1) (0, 1, 1)12 model was established and fitted the time series of food borne diseases in Jinan well, with AIC=687.22. Using Ljung Box function, P=0.499 was obtained, indicating that the residual error belonged to the white noise series. The data in 2021 was used to test the model extrapolation effect, and the actual values fell within the 95% confidence interval of the predicted value. The model prediction effect was relatively ideal. Conclusion SARIMA (2, 0, 1) (0, 1, 1)12 model can better fit the temporal change of foodborne diseases, and therefore can be used to fit and predict the monthly incidence of foodborne diseases.
5.Exploring Mechanism of Neferine in Promoting Vascular Regeneration Against Cerebral Ischemia Based on Mitochondrial MCU Channel
Qiman ZHANG ; Yanhua GAO ; Wenjie WU ; Wei YANG ; Chen LIU ; Shuting LI ; Bingjie CAI ; Jialin YANG ; Ying ZHANG ; Jing MA ; Shaojing LI
Chinese Journal of Experimental Traditional Medical Formulae 2024;30(24):103-113
ObjectiveTo investigate the mechanism of neferine(Nef) in promoting vascular regeneration against cerebral ischemia through modulation of mitochondrial calcium uniporter(MCU) ion channel. MethodTaking the area of subintestinal vessels in microvascular deficiency zebrafish as an index, the vascular regenerative efficacy of Nef was evaluated, and the median effective concentration(EC50) was calculated. Rats were randomly divided into a sham operation group, a model group, a positive drug group(butylphthalide, 6 mg·kg-1), and Nef low, medium, and high dose groups(0.125, 0.625, 3.125 μg·kg-1). Except for the sham operation group, the middle cerebral artery occlusion(MCAO) model was established in other groups. After modeling, the groups were administered the corresponding dose of drugs by gavage, while the sham operation and model groups received equal volumes of saline, once a day for 7 consecutive days. Neurobehavioral scores were assessed for each group of rats, and the infarct rate of ischemic brain tissue was calculated by 2,3,5-triphenyltetrazolium chloride(TTC) staining. The regional cerebral blood flow(rCBF) of each group was measured using a speckle contrast imaging. Immunofluorescence and Western blot were conducted to detect the expression of vascular endothelial growth factor(VEGF), platelet endothelial cell adhesion molecule-1(CD31), and hypoxia-inducible factor-1α(HIF-1α) proteins in each group. Human umbilical vein endothelial cells(HUVECs) were divided into the normal group, model group, positive drug group(astragaloside Ⅳ, 10 μmol·L-1), and Nef group (32 nmol·L-1). In the verification of mitochondrial protection of Nef and its mechanism in promoting vascular regeneration, the spermine(MCU agonist) and Nef+spermine group were added. HUVECs model of oxygen-glucose deprivation(OGD) was established in all groups except the normal group, the cell viability was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay, and cell migration ability was evaluated through scratch and tube formation assays. Fluorescent probes(Rhod-2 AM, Fluo-3 AM, JC-1, Calcein AM) and a cellular energy metabolism analyzer were used to analyze the mitochondrial protective effects of Nef. Molecular docking was performed to predict the binding ability of Nef with MCU and HIF-1α, and Western blot was used to detect the effects of Nef on the protein expressions of MCU, B-cell lymphoma-2 associated X protein(Bax), Caspase-3 and HIF-1α in the OGD model HUVECs. ResultThe results of vascular regeneration in microvascular deficiency zebrafish showed that compared to the normal group, the area of subintestinal vessels in the model group significantly decreased(P<0.01). Compared to the model group, different concentrations of Nef could significantly increase the area of subintestinal vessels(P<0.01), with the maximum tolerated concentration of 10.24 μmol·L-1 and the EC50 of 0.23 μmol·L-1. Anti-cerebral ischemia results on MCAO rats showed that compared to the sham operation group, the model group had a significant decrease in rCBF and a significant increase in infarct rate, while CD31 expression significantly decreased(P<0.01), and VEGF and HIF-1α protein expressions significantly increased(P<0.05). Compared to the model group, the treated groups showed significant increases in rCBF, significant reductions in infarct volume, and significant increases in CD31, VEGF, and HIF-1α protein expression(P<0.01). Cell experiment results showed that compared to the normal group, the model group had decreased cell viability and migration ability, increased intracellular Ca2+ and mitochondrial Ca2+ levels, reduced mitochondrial permeability transition pore(MPTP) opening, and decreased mitochondrial energy metabolism capability, with increased expressions of MCU, Bax, Caspase-3 and HIF-1α proteins(P<0.05, P<0.01). Compared to the model group, the Nef group showed increased cell viability and migration ability, decreased intracellular Ca2+ and mitochondrial Ca2+ levels, increased MPTP opening, enhanced mitochondrial energy metabolism capability, decreased expressions of MCU, Bax and Caspase-3 proteins, and increased HIF-1α protein expression(P<0.05, P<0.01). ConclusionNef can stabilize mitochondrial membrane potential and inhibit mitochondrial apoptosis. By down-regulating the expression of MCU, it suppresses the activation of intracellular Bax and Caspase-3 while activating the HIF-1α signaling pathway, enhancing the expression of VEGF and CD31, thereby promoting vascular regeneration to treat ischemic brain injury.
6.Analysis of Clinical Characteristics and Death Risk Factors in Patients with Community-acquired Pneumonia Complicated with Diabetes
Jianfang MA ; Xiaoling HUANG ; Yanhua LI ; Di MA ; Kaifen YUAN
Journal of Kunming Medical University 2024;45(2):123-130
Objective To explore the clinical characteristics and risk factors of death during hospitalization in patients with community-acquired pneumonia(CAP)complicated with diabetes mellitus(DM).Methods A retrospective analysis was performed on 566 patients with CAP hospitalized in the Second Affiliated Hospital of Kunming Medical University from January 2018 to January 2022.The patients were divided into simple CAP group(n=478)and CAP combined with diabetes(CAP+DM)group(n=88)according to whether they had diabetes,and then CAP+DM group(n=88)was divided into survival group(n=69)and death group(n =19)according to whether the patients died during hospitalization.The clinical data and laboratory test indicators of patients in different groups were compared.Cox regression analysis was used to screen the risk factors of death during hospitalization in the CAP+DM group.Receiver operating characteristic(ROC)curve was plotted to evaluate the predictive value of independent risk factors on hospitalization death.Results Compared with the simple CAP group,the CAP+DM group had significant differences in age,concomitant hypertension,coronary heart disease,CURB-65 score,neutrophil to lymphocyte ratio(NLR),C-reactive protein(CRP),procalcitonin(PCT),albumin(ALB),prealbumin(PA),glucose(GLU),serum potassium(K),calcium(Ca),phosphorus(P),magnesium(Mg),lactic acid(Lac),non-invasive ventilation time,ICU occupancy rate and mortality rate(P<0.05);Compared with the survival group,there were statistically significant differences in CURB-65 score,NLR,CRP,PCT,GIU,ALB,PA,serum iron(Fe),Ca,non-invasive ventilation time,and ICU admission rate among the death group patients(P<0.05).Cox regression analysis showed that the increase of NLR level and the decrease in PA level were the risk factors for in-hospital death in patients with CAP complicated with diabetes(P<0.05).When the PA cutoff value was 91 mg/L,the AUC,sensitivity,and specificity for predicting in-hospital death of CAP patients with diabetes were 0.849,84.2%and 81.2%,respectively.Conclusion Patients with CAP combined with diabetes are more serious and have worse prognosis than those with CAP alone.PA has a good predictive value for the prognosis of these patients.Early detection and active intervention should be carried out to reduce the in-hospital mortality of patients.
7.The application of family empowerment model on the primary caregivers of first-episode stroke dysphagia patients
Hong YU ; Jing DU ; Qian XU ; Mingming XU ; Xiangge FAN ; Fan ZHANG ; Xueyun WENG ; Xiaoming MA ; Yanhua HOU ; Linqing LI
Chinese Journal of Practical Nursing 2024;40(4):263-271
Objective:To explore the effect of family empowerment model on the improvement of swallowing care ability and care preparedness of primary caregivers of first-episode stroke dysphagia patients, further to explore its impact on patients′s wallowing function and life quality.Methods:This study was a randomized controlled study. From January 2021 to December 2022, 80 main caregivers of patients with dysphagia caused by manual stroke admitted to the Department of Acupuncture and Moxibustion, Shenzhen Hospital of Traditional Chinese Medicine were selected as the research objects, and 40 cases in the control group and 40 cases in the observation group were selected by random number table method. The control group were treated with conventional nursing care of first-episode stroke dysphagia patients in the acupuncture and moxibustion Department. On the basis of the conventional care in the control group, the observation group were treated with family empowerment model intervention for 14 days and was followed up for 28 days. Primary caregivers′ swallowing care ability, Caregiver Preparedness Scale (CPS), patients′ swallowing function rate, Swallowing Related Quality of Life (SWALQOL) were used to evaluate the effects before intervention and at the end of intervention.Results:There were 18 males and 19 females primary caregivers in the control group, aged (55.61 ± 7.43) years old. There were 18 males and 21 females primary caregivers in the observation group, aged (58.23 ± 8.22) years old. The swallowing care ability score showed a statistically significant difference between the observation group (143.47 ± 3.96) and the control group (107.74 ± 1.43) ( t=-26.76, P<0.05). After intervention, the caregiver preparedness scale was (26.11 ± 3.81) in the observation group, and (18.35 ± 4.54) in the control group, and the difference was statistically significant ( t=-4.11, P<0.05).The patients′ swallowing function rate and SWALQOL score were respectively 97.44% (38/39) and (91.41 ± 8.08) points in the observation group, and 72.97% (27/37) and (80.33 ± 4.21) points in the control group, and the difference was both statistically significant ( χ2=10.76, t=-2.54, both P<0.05). Conclusions:The implementation of family empowerment model could enhance the swallowing care ability and care preparedness of primary caregivers of the first-episode stroke dysphagia patients, which could further improve patients′ swallowing function and life quality.
8.Effect of Yiqi Tongmai Formula in Intervening in Liver Inflammation and Lipidosis in ApoE-∕- Mice Based on NF-κB/NLRP3 Signaling Pathway
Yuhan CHEN ; Quanna REN ; Kun WANG ; Tingting SU ; Yanhua YANG ; Ming MA ; Yu ZHANG ; Xu ZHAO
Chinese Journal of Experimental Traditional Medical Formulae 2024;30(15):64-72
ObjectiveTo investigate the effect of Yiqi Tongxin formula (YQTM) on liver inflammation in apolipoprotein E-∕- (ApoE-∕-) mice by regulating the nuclear transcription factor-κB (NF-κB)/NOD-like receptor protein 3 (NLRP3) signaling pathway. MethodForty ApoE-∕- mice were randomly divided into a model group, an atorvastatin group (positive drug group), and low-, medium-, and high-dose YQTM groups (0.39, 0.78, 1.56 g·kg-1). Each drug administration group was given the corresponding concentration of the drug by gavage on the basis of high-fat feeding for 12 consecutive weeks. Eight C57BL/6J mice were used as a blank group and fed with normal chow. After 12 weeks, oil red O staining and Masson staining were used to observe the aortic lesions in mice and to determine whether the modeling was successful. Oil red O staining was used to observe the lipidosis in the livers of mice. Hematoxylin-eosin (HE) staining was used to observe the tissue lesions in the livers of mice. Masson staining was used to observe the distribution of collagen fibers in the livers of mice. Enzyme markers were used to detect the total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL-C), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) in mouse serum, as well as total cholesterol (TC) and triglyceride (TG) in the liver. Interleukin-1β (IL-1β) and IL-18 were detected in mouse liver by enzyme-linked immunosorbent assay (ELISA). Immunohistochemistry (IHC) was utilized to observe the expression regions of NF-κB and NLRP3 in the livers of mice. Western blot was employed to detect the protein expression levels of NF-κB, NF-κB inhibitory protein (IκB), IκB kinase β (IKKβ), phosphorylated NF-κB (p-NF-κB), phosphorylated IκB (p-IκB), phosphorylated IKK β (p-IKKβ), NLRP3, and Caspase-1 in the livers of mice. ResultCompared with the blank group, the model group showed severe aortic lipidosis, and the intracellular fat droplets in the livers aggregated in large quantities. The cytoplasm was filled with fat vacuoles(P<0.01). The serum levels of TG, TC, LDL-C, AST, and ALT were significantly elevated in the mice(P<0.01). TG and TC levels were elevated in the liver(P<0.01). The levels of IL-1β and IL-18 in liver tissue, as well as the protein expression levels of NF-κB, IκB, IKKβ, p-NF-κB, p-IκB, p-IKKβ, NLRP3, and Caspase-1 in the liver were significantly elevated(P<0.01). Compared with the model group, the aortic arch plaques of mice in each YQTM group were attenuated, and the fat aggregation in the liver was reduced. The inflammatory cell infiltration was alleviated(P<0.05,P<0.01). The serum levels of TG, TC, LDL-C, AST, and ALT were significantly reduced(P<0.05,P<0.01). TG and TC levels in the liver were reduced. The IL-1β and IL-18 levels in liver tissue, as well as protein expression levels of NF-κB, IκB, IKKβ, p-NF-κB, p-IκB, p-IKKβ, NLRP3, and Caspase-1 in the liver were significantly reduced(P<0.05,P<0.01). ConclusionThe intervention mechanism of YQTM on liver inflammation in ApoE-∕- mice may be related to the down-regulation of the NF-κB/NLRP3 signaling pathway.
9.Chinese Medicine Regulates Hepatocellular Carcinoma-related Signaling Pathways: A Review
Chun YU ; Fen GAO ; Lanlan ZHENG ; Cai GUO ; Yanfang HE ; Jiaojiao XIE ; Xuan ZHANG ; Yanhua MA
Chinese Journal of Experimental Traditional Medical Formulae 2024;30(15):232-243
Hepatocellular carcinoma (HCC) is a common tumor in the digestive tract, the formation mechanism of which remains to be fully elucidated. Although surgery, radiation, chemotherapy, targeted therapy, and immunotherapy have achieved significant results in the treatment of HCC, these methods are accompanied by a considerable number of adverse reactions and complications. In recent years, Chinese medicine has shown remarkable efficacy in the treatment of HCC, and both basic experiments and clinical studies have confirmed the effectiveness of Chinese medicine, which exerts therapeutic effects via multiple components and multiple targets. However, the pathogenesis of HCC is exceptionally complex and not fully understood, which means that studies remain to be carried out regarding the specific mechanism of Chinese medicine in preventing and treating HCC. Network pharmacology and molecular biology can be employed to decipher the mechanism of Chinese medicine in the treatment of diseases. Studies have shown that Chinese medicine can regulate various pathways such as the mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt), Hedgehog, Wnt/β-catenin, nuclear factor-κB (NF-κB), Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3), and transforming growth factor-β (TGF-β)/Smad signaling pathways. Chinese medicine can exhibit its anti-HCC effects by inducing cell apoptosis, inhibiting cell proliferation and migration, and blocking the cell cycle via the above pathways. However, the specific mechanisms remain to be systematically studied. This study comprehensively reviews the regulatory effects of Chinese medicine on HCC-related signaling pathways to reveal the molecular mechanisms of Chinese medicine in the treatment of HCC. This view holds the promise of providing new targets, new perspectives, and new therapies for HCC treatment and advancing the modernization and development of Chinese medicine.
10.Antibacterial performance of cerium oxide nanoenzyme against Escherichia coli
Heishu ZHENG ; Yingjuan ZHANG ; Yanhua WEI ; Hui HUANG ; Xiangyu MA ; Hongbing LIAO
Chinese Journal of Tissue Engineering Research 2024;28(22):3496-3501
BACKGROUND:The increase in multi-drug resistant bacterial infections has become a major problem in modern healthcare due to the development of bacterial resistance to antibiotics and the development of new antibacterial alternative drug materials is of great importance. OBJECTIVE:To synthesize and perform a series of characterization of a CeO2 nanoenzyme to investigate its biocompatibility and antibacterial properties against Escherichia coli. METHODS:CeO2 nanoenzymes were synthesized using a hydrothermal method.The morphology,product composition,and chemical composition were analyzed using characterization methods such as X-ray diffraction,X-ray photoelectron spectroscopy,Fourier infrared analysis,Raman spectroscopy,scanning electron microscopy,and transmission electron microscopy.The peroxide-mimetic enzyme activity of CeO2 nanoenzymes was characterized using TMB color development assay.The toxic effect of CeO2 nanoenzymes at different concentrations(10,25,and 50 μg/mL)on mouse fibroblast L929 cells was evaluated using the CCK-8 assay.The antibacterial properties of CeO2 nanoenzymes against Escherichia coli under different conditions were evaluated using the plate coating method.Changes in intra-bacterial reactive oxygen species after treatment with different conditions were detected using a reactive oxygen species detection kit. RESULTS AND CONCLUSION:(1)The morphology of the synthesized CeO2 nanoparticles was rod-shaped,with Ce3+ accounting for 29.87%of the total Ce3+/Ce4+ and an average grain size of 7.4 nm.In a slightly acidic environment containing TMB and pH=5.5,CeO2 nanoenzymes mixed with H2O2 showed excellent peroxidase activity,but did not show peroxidase simulated activity at pH=7.4.(2)There was no statistically significant difference in the toxic effects of CeO2 nanoparticles at various mass concentrations on mouse fibroblast L929 cells.(3)In a slightly acidic environment at pH 5.5,Escherichia coli was inhibited to a certain extent in the presence of CeO2 nanoenzyme alone at a concentration of 10 μg/mL,with a decrease in CFU results of about 0.5 log(P<0.01);in a slightly acidic environment containing 50 μmol/L H2O2,CeO2 nanoenzyme showed excellent antibacterial effects against Escherichia coli,with a decrease in Escherichia coli CFU results of by about 1.5 log(P<0.001).After CeO2 nanoenzymes interacted with Escherichia coli,the level of reactive oxygen species in Escherichia coli increased(P<0.05);after CeO2 nanoenzymes interacted with Escherichia coli together with H2O2,the level of reactive oxygen species in Escherichia coli increased significantly(P<0.001).(4)The results show that the CeO2 nanoenzymes have good biocompatibility,are inherently antibacterial,and can exhibit peroxidase activity in a slightly acidic environment containing low concentrations of H2O2,and generate reactive oxygen species to kill bacteria,thus showing excellent antibacterial effects.


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