Electrochemical treatment in KOH improves carbon nanomaterial performance to multiple neurochemicals.

Carbon-fiber microelectrodes (CFMEs) are primarily used to detect neurotransmitters in vivo with fast-scan cyclic voltammetry (FSCV) but other carbon nanomaterial electrodes are being developed. CFME sensitivity to dopamine is improved by applying a constant 1.5 V vs. Ag/AgCl for 3 minutes while dipped in 1 M KOH, which etches the surface and adds oxygen functional groups. However, KOH etching of other carbon nanomaterials and applications to other neurochemicals have not been investigated. Here, we explored KOH etching of CFMEs and carbon nanotube yarn microelectrodes (CNTYMEs) to characterize sensitivity to dopamine, epinephrine, norepinephrine, serotonin, and 3,4-dihydroxyphenylacetic acid (DOPAC). With CNTYMEs, the potential was applied in KOH for 1 minute because the electrode surface cracked with the longer time. KOH treatment increased electrode sensitivity to each cationic neurotransmitter roughly 2-fold for CFMEs, and 2- to 4-fold for CNTYMEs. KOH treatment decreased the background current of the CFMEs by etching the surface carbon; however, KOH-treatment increased the CNTYME background current because the potential separates individual nanotubes. For DOPAC, the current increase was smaller at CNTYMEs because it is anionic and was repelled by the negative holding potential and did not access the crevices. XPS and Raman spectroscopy showed that KOH treatment changed the CNTYME surface chemistry by increasing defect sites and adding oxide functional groups. KOH-treated CNTYMEs had less fouling to serotonin than normal CNTYMEs. Therefore, KOH treatment activates both CFMEs and CNTYMEs and could be used in biological measurements to increase the sensitivity and decrease fouling for neurochemical measurements.

3D-Printed Carbon Nanoneedle Electrodes for Dopamine Detection in Drosophila.

In vivo electrochemistry in small brain regions or synapses requires nanoelectrodes with long straight tips for submicron scale measurements. Nanoelectrodes can be fabricated using a Nanoscribe two-photon printer, but annealed tips curl if they are long and thin. We propose a new pulling-force strategy to fabricate a straight carbon nanoneedle structure. A micron-width bridge is printed between two blocks. The annealed structure shrinks during pyrolysis, and the blocks create a pulling force to form a long, thin, and straight carbon bridge. Parameterization study and COMSOL modeling indicate changes in the block size, bridge size and length affect the pulling force and bridge shrinkage. Electrodes were printed on niobium wires, insulated with aluminum oxide, and the bridge cut with focused ion beam (FIB) to expose the nanoneedle tip. Annealed needle diameters ranged from 400 nm to 5.25 µm and length varied from 50.5 µm to 146 µm. The electrochemical properties are similar to glassy carbon, with good performance for dopamine detection with fast-scan cyclic voltammetry. Nanoelectrodes enable biological applications, such as dopamine detection in a specific Drosophila brain region. Long and thin nanoneedles are generally useful for other applications such as cellular sensing, drug delivery, or gas sensing.

Carbon nanospike coated nanoelectrodes for measurements of neurotransmitters.

Carbon nanoelectrodes enable the detection of neurotransmitters at the level of single cells, vesicles, synapses and small brain structures. Previously, the etching of carbon fibers and 3D printing based on direct laser writing have been used to fabricate carbon nanoelectrodes, but these methods lack the ability of mass manufacturing. In this paper, we mass fabricate carbon nanoelectrodes by growing carbon nanospikes (CNSs) on metal wires. CNSs have a short, dense and defect-rich surface that produces remarkable electrochemical properties, and they can be mass fabricated on almost any substrate without using catalysts. Tungsten wires and niobium wires were electrochemically etched in batch to form sub micrometer sized tips, and a layer of CNSs was grown on the metal wires using plasma-enhanced chemical vapor deposition (PE-CVD). The thickness of the CNS layer was controlled by the deposition time, and a thin layer of CNSs can effectively cover the entire metal surface while maintaining the tip size within the sub micrometer scale. The etched tungsten wires produced tapered conical nanotips, while the etched niobium wires were long and thin. Both showed excellent sensitivity for the detection of outer sphere ruthenium hexamine and the inner sphere test compound ferricyanide. The CNS nanosensors were used for the measurement of dopamine, serotonin, ascorbic acid and DOPAC with fast-scan cyclic voltammetry. The CNS nanoelectrodes had a large surface area and numerous defect sites, which improved the sensitivity, electron transfer kinetics and adsorption. Finally, the CNS nanoelectrodes were compared with other nanoelectrode fabrication methods, including flame etching, 3D printing, and nanopipettes, which are slower to make and more difficult for mass fabrication. Thus, CNS nanoelectrodes are a promising strategy for the mass fabrication of nanoelectrode sensors for neurotransmitters.

Different Electrochemical Behavior of Cationic Dopamine from Anionic Ascorbic Acid and DOPAC at CNT Yarn Microelectrodes.

Carbon nanotube yarn microelectrodes (CNTYMEs) have micron-scale surface crevices that momentarily trap molecules. CNTYMEs improve selectivity among cationic catecholamines because secondary reactions are enhanced, but no anions have been studied. Here, we compared fast-scan cyclic voltammetry (FSCV) of dopamine and anionic interferents 3,4 dihydroxyphenylacetic acid (DOPAC) and L-ascorbic acid (AA) at CNTYMEs and carbon fiber microelectrodes (CFMEs). At CFMEs, dopamine current decreases with increasing FSCV repetition frequency at pH 7.4, whereas DOPAC and AA have increasing currents with increasing frequency, because of less repulsion at the negative holding potential. Both DOPAC and AA have side reactions after being oxidized, which are enhanced by trapping. At pH 4, the current increases for DOPAC and AA because they are not repelled. In addition, AA has a different oxidation pathway at pH 4, and an extra peak in the CV is enhanced by trapping effects at CNTYMEs. At pH 8.5, co-detection of dopamine in the presence of DOPAC and AA is enhanced at 100 Hz frequency because of differences in secondary peaks. Thus, the trapping effects at CNTYMEs affects anions differently than cations and secondary peaks can be used to identify dopamine in mixture of AA and DOPAC with FSCV.

Influence of Geometry on Thin Layer and Diffusion Processes at Carbon Electrodes.

The geometric structure of carbon electrodes affects their electrochemical behavior, and large-scale surface roughness leads to thin layer electrochemistry when analyte is trapped in pores. However, the current response is always a mixture of both thin layer and diffusion processes. Here, we systematically explore the effects of thin layer electrochemistry and diffusion at carbon fiber (CF), carbon nanospike (CNS), and carbon nanotube yarn (CNTY) electrodes. The cyclic voltammetry (CV) response to the surface-insensitive redox couple Ru(NH3)63+/2+ is tested, so the geometric structure is the only factor. At CFs, the reaction is diffusion-controlled because the surface is smooth. CNTY electrodes have gaps between nanotubes that are about 10 µm deep, comparable with the diffusion layer thickness. CNTY electrodes show clear thin layer behavior due to trapping effects, with more symmetrical peaks and ΔEp closer to zero. CNS electrodes have submicrometer scale roughness, so their CV shape is mostly due to diffusion, not thin layer effects. However, even the 10% contribution of thin layer behavior reduces the peak separation by 30 mV, indicating ΔEp is influenced not only by electron transfer kinetics but also by surface geometry. A new simulation model is developed to quantitate the thin layer and diffusion contributions that explains the CV shape and peak separation for CNS and CNTY electrodes, providing insight on the impact of scan rate and surface structure size. Thus, this study provides key understanding of thin layer and diffusion processes at different surface structures and will enable rational design of electrodes with thin layer electrochemistry.

Electrochemical treatment in KOH renews and activates carbon fiber microelectrode surfaces.

Carbon fiber microelectrodes (CFMEs) are the standard electrodes for fast-scan cyclic voltammetry (FSCV) detection of neurotransmitters. CFMEs are generally used untreated but the surface can be activated with different treatments to improve electrochemical performance. In this work, we explored electrochemical treatments to clean and activate the CFME surface. We used different solution conditions for electrochemical treatment and found that electrochemical pretreatment in KOH outperforms treatment in KCl, H2O2, or HCl by accelerating the surface renewal process. The etching rate of carbon with electrochemical treatment in KOH is 37 nm/min, which is 10 times faster than that in the other solutions. Electrochemical treatment in KOH for several minutes regenerates a new carbon surface, which introduces more oxygen functional groups beneficial for adsorption and electron transfer. The KOH-treated CFMEs improved the limit of detection (LOD) to 9 ± 2 nM from 14 ± 4 nM for untreated CFMEs, and they successfully detected stimulated dopamine release in rat brain slices, demonstrating that they are stable and sensitive enough to use in biological systems. Electrochemical treatment in KOH completely restores the electrode sensitivity after biofouling. The proposed electrochemical treatment is simple and fast and can be applied prior to using CFMEs or after use to restore the surface. Thus, the method has potential to be a standard step to clean the carbon surface, or restore the sensitivity of electrodes from biofouling.

Ginsenoside Rk1 alleviates LPS-induced depression-like behavior in mice by promoting BDNF and suppressing the neuroinflammatory response.

Ginsenoside Rk1, a saponin component produced by heat-processed ginseng, possesses anti-inflammatory and antitumor activities. The aim of our study was to explore the effects of Rk1 on Lipopolysaccharide (LPS)-induced depression-like behavior in mice and to observe its effects on oxidative stress, the inflammatory response and brain-derived neurotrophic factor (BDNF) - tropomyosin-related kinase B (TrkB) signaling. After mice were pretreated with Rk1 (5, 10, and 20 mg/kg), the immobility time in both the forced swimming test (FST) and the tail suspension test (TST) was reduced, suggesting that Rk1 effectively improved depression-like symptoms. Rk1 (10 and 20 mg/kg) and Fluoxetine (Flu, 20 mg/kg) increased the activity of the antioxidant enzyme SOD in the brain and protected against lipid peroxidation. Different concentrations of Rk1 (10 and 20 mg/kg) and Flu significantly decreased the levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1 in serum, while Rk1 (5, 10, and 20 mg/kg) and Flu reduced the concentrations of IL-6 in a dose-dependent manner. Western blot analysis showed that the administration of Rk1 (20 mg/kg) and Flu significantly downregulated the level of Sirt1 and that Rk1 (5, 10, and 20 mg/kg) and Flu inhibited the p-NF-κb/NF-κb and p-IκB-α/IκB-α ratios, which indicated that the neuroprotective effect of Rk1 may be related to the suppression of inflammation. In addition 5, 10 and 20 mg/kg Rk1 significantly attenuated the LPS-induced decreases in BDNF and TrkB. These results indicated that Rk1 acts as an antidepressant through its antioxidant activity, the inhibition of neuroinflammation, and the positive regulation of the BDNF-TrkB pathway. This study may help develop active ginsenoside-based compounds for neurodegenerative diseases.

Thin layer cell behavior of CNT yarn and cavity carbon nanopipette electrodes: Effect on catecholamine detection.

Carbon nanotube yarn microelectrodes (CNTYMEs) are an alternative to carbon-fiber microelectrodes (CFMEs) with interesting electrochemical properties because analyte is momentarily trapped in cavities between the CNTs. Here, we compare fast-scan cyclic voltammetry (FSCV) detection of catecholamines, including dopamine, norepinephrine, and epinephrine, at CNTYMEs, CFMEs, as well as cavity carbon nanopipette electrodes (CNPEs). At CFMEs, current decreases dramatically at high FSCV repetition frequencies. At CNTYMEs, current is almost independent of FSCV repetition frequency because the analytes are trapped in the crevices between CNTs, and thus the electrode acts like a thin-layer cell. At CFMEs, small cyclization product peaks are observed due to an intramolecular cyclization reaction to form leucocatecholamine, which is electroactive, and these peaks are largest for the secondary amine epinephrine. At CNTYMEs, more of the leucocatecholamine cyclization product is detected for all catecholamines because of the enhanced trapping effects, particularly at higher repetition rates where the reaction occurs more frequently and more product is accumulated. For epinephrine, the secondary peaks have larger currents than the primary oxidation peaks at 100 Hz, and similar trends are observed with faster scan rates and 500 Hz repetition frequencies. Finally, we examined CNPEs, which also momentarily trap neurotransmitters. Similar to CNTYMEs, at CNPEs, catecholamines have robust cyclization peaks, particularly at high repetition rates. Thus, CNTYMEs and CNPEs have thin layer cell behavior that facilitates high temporal resolution measurements, but catecholamines CVs are complicated by cyclization reactions. However, those additional peaks could be useful in discriminating the analytes, particularly epinephrine and norepinephrine.

Immunomodulatory Effects of (24R)-Pseudo-Ginsenoside HQ and (24S)-Pseudo-Ginsenoside HQ on Cyclophosphamide-Induced Immunosuppression and Their Anti-Tumor Effects Study.

(24R)-pseudo-ginsenoside HQ (R-PHQ) and (24S)-pseudo-ginsenoside HQ (S-PHQ) are the main metabolites of (20S)-ginsenoside Rh2 (Rh2) in vivo. In this study, we found that Rh2, R-PHQ, and S-PHQ upregulated the innate and adaptive immune response in cyclophosphamide (CTX) induced-immunocompromised mice as evidenced by the number of leukocytes, cellular immunity, and phagocytosis of macrophages. Spleen T-lymphocyte subpopulations and the serum cytokines level were also balanced in these immunosuppressed mice. Furthermore, co-administration with R-PHQ or S-PHQ did not compromise the antitumor activity of CTX in the hepatoma H22-bearing mice. Treatment with R-PHQ and S-PHQ clearly induced the apoptosis of tumor cells, significantly increased the expression of Bax, and remarkably inhibited the expression of Bcl-2 and vascular endothelial growth factor (VEGF) in H22 tumor tissues. The anti-tumor activity of R-PHQ and S-PHQ could be related to the promotion of tumor apoptosis and inhibition of angiogenesis and may involve the caspase and VEGF signaling pathways. This study provides a theoretical basis for further study on R-PHQ and S-PHQ.

Study on Antidepressant Activity of Pseudo-Ginsenoside HQ on Depression-Like Behavior in Mice.

Suppressive effects of ginsenoside Rh2 (Rh2), (24R)-pseudo-ginsenoside HQ (R-PHQ), and (24S)-pseudo-ginsenoside HQ (S-PHQ) against lipopolysaccharide (LPS)-induced depression-like behavior were evaluated using the forced swimming test (FST) and tail suspension test (TST) in mice. Pretreatment with Rh2, R-PHQ, and S-PHQ significantly decreased immobility time in FST and TST with clear dose-dependence, and significantly downregulated levels of serum tumor necrosis factor-α and interleukin-6, and upregulated superoxide dismutase activity in the hippocampus of LPS-challenged mice. Furthermore, R-PHQ and S-PHQ significantly increased the expression of the brain-derived neurotrophic factor (BDNF), tropomyosin-related kinase B (TrkB), sirtuin type 1 (Sirt1), and nuclear-related factor 2, and inhibited the phosphorylation of inhibitor of κB-α and nuclear factor-κB (NF-κB) in the hippocampus of LPS-challenged mice. Additionally, the antidepressant-like effect of R-PHQ was found related to the dopaminergic (DA), γ-aminobutyric acid (GABA)ergic, and noradrenaline systems, while the antidepressive effect of S-PHQ was involved in the DA and GABAergic systems. Taken together, these results suggested that Rh2, R-PHQ, and S-PHQ produced significant antidepressant-like effects, which may be related to the BDNF/TrkB and Sirt1/NF-κB signaling pathways.

A Comparative Study on the Effects of Different Parts of Panax ginseng on the Immune Activity of Cyclophosphamide-Induced Immunosuppressed Mice.

The objective of the present study was to compare the effects of the immunological activity of various parts (root/stem/leaf/flower/seed) of five-year-old ginseng on the immune system of immunosuppressive mice. Immunosuppression was induced by cyclophosphamide (CTX) in the mouse model, whereas levamisole hydrochloride tablet (LTH) was used for the positive control group. We found that ginseng root (GRT), ginseng leaf (GLF), and ginseng flower (GFR) could relieve immunosuppression by increased viability of NK cells, enhanced immune organ index, improved cell-mediated immune response, increased content of CD4⁺ and ratio of CD4⁺/CD8⁺, and recovery of macrophage function, including carbon clearance, phagocytic rate, and phagocytic index, in immunodeficient mice. However, ginseng stem (GSM) and ginseng seed (GSD) could only enhance the thymus indices, carbon clearance, splenocyte proliferation, NK cell activities, and the level of IL-4 in immunosuppressed mice. In CTX-injected mice, GRT and GFR remarkably increased the protein expression of Nrf2, HO-1, NQO1, SOD1, SOD2, and CAT in the spleen. As expected, oral administration of GRT and GFR markedly enhanced the production of cytokines, such as IL-1ß, IL-4, IL-6, IFN-γ, and TNF-α, compared with the CTX-induced immunosuppressed mice, and GRT and GFR did this relatively better than GSM, GLF, and GSD. This study provides a theoretical basis for further study on different parts of ginseng.

Carbon microelectrodes with customized shapes for neurotransmitter detection: A review.

Carbon is a popular electrode material for neurotransmitter detection due to its good electrochemical properties, high biocompatibility, and inert chemistry. Traditional carbon electrodes, such as carbon fibers, have smooth surfaces and fixed shapes. However, newer studies customize the shape and nanostructure the surface to enhance electrochemistry for different applications. In this review, we show how changing the structure of carbon electrodes with methods such as chemical vapor deposition (CVD), wet-etching, direct laser writing (DLW), and 3D printing leads to different electrochemical properties. The customized shapes include nanotips, complex 3D structures, porous structures, arrays, and flexible sensors with patterns. Nanostructuring enhances sensitivity and selectivity, depending on the carbon nanomaterial used. Carbon nanoparticle modifications enhance electron transfer kinetics and prevent fouling for neurochemicals that are easily polymerized. Porous electrodes trap analyte momentarily on the scale of an electrochemistry experiment, leading to thin layer electrochemical behavior that enhances secondary peaks from chemical reactions. Similar thin layer cell behavior is observed at cavity carbon nanopipette electrodes. Nanotip electrodes facilitate implantation closer to the synapse with reduced tissue damage. Carbon electrode arrays are used to measure from multiple neurotransmitter release sites simultaneously. Custom-shaped carbon electrodes are enabling new applications in neuroscience, such as distinguishing different catecholamines by secondary peaks, detection of vesicular release in single cells, and multi-region measurements in vivo.

MPCVD-Grown Nanodiamond Microelectrodes with Oxygen Plasma Activation for Neurochemical Applications.

Nanodiamonds (NDs) are a carbon nanomaterial that has a diamond core with heteroatoms and defects at the surface. The large surface area, defect sites, and functional groups on NDs make them a promising material for electrochemical sensing. Previously, we dip-coated ND onto carbon-fiber microelectrodes (CFMEs) and found increases in sensitivity, but the coating was sparse. Here, we directly grew thin films of ND on niobium wires using microwave plasma chemical vapor deposition (MP-CVD) to provide full surface coverage. ND microelectrodes show a reliable performance in neurotransmitter detection with good antifouling properties. To improve sensitivity, we oxygen plasma etched ND films to activate the surface and intentionally add defects and oxygen surface functional groups. For fast-scan cyclic voltammetry detection of dopamine, oxygen plasma-etching increases the sensitivity from 21 nA/µM to 90 nA/µM after treatment. Fouling was tested by repeated injections of serotonin or tyramine, and both ND and plasma oxidized nanodiamond (NDO) microelectrodes maintain their currents better compared to CFMEs and therefore are more antifouling. A biofouling test in brain slices shows that ND microelectrodes barely have any current drop, while the more hydrophilic NDO microelectrodes decrease more, but still not as much as CFMEs. Overall, grown ND microelectrodes are promising in neurotransmitter detection with excellent fouling resistance, whereas oxygen plasma etching slightly lowers the fouling resistance but dramatically increases sensitivity.

Transformation Mechanism of Rare Ginsenosides in American Ginseng by Different Processing Methods and Antitumour Effects.

The mechanism by which ginsenosides from Panax quinquefolium L. transform into rare saponins by different processing methods and their antitumour effects have yet to be fully elucidated. Our study aimed to detect the effect of amino acids and processing methods on the conversion of ginsenosides in American ginseng to rare ginsenosides, using 8 monomeric ginsenosides as substrates to discuss the reaction pathway and mechanism. S180 tumour-bearing mice were established to study the antitumour effects of American ginseng total saponins (AGS-Q) or American ginseng total saponins after transformation (AGS-H) synergistic CTX. The results showed that aspartic acid was the best catalyst, and the thermal extraction method had the best effect. Under the optimal conditions, including a reaction temperature of 110°C, an aspartic acid concentration of 5%, a reaction time of 2.5 h and a liquid-solid ratio of 30 mL/g, the highest conversion of Rk1 and Rg5 was 6.58 ± 0.11 mg/g and 3.74 ± 0.05 mg/g, respectively. In the reaction pathway, the diol group saponins participated in the transformation process, and the triol group saponins basically did not participate in the transformation process. AGS-Q or AGS-H synergistic CTX, or AGS-H synergistic CTX/2 could significantly increase the tumour inhibition rate, spleen index and white blood cell count, had a significant upregulation effect on IL-2 and IL-10 immune cytokines; significantly restored the ratio of CD4+/CD8+; and significantly inhibited the level of CD4+CD25+. AGS-Q or AGS-H synergistic with CTX or CTX/2 can significantly upregulate the expression of Bax and cleaved-Caspase-3 and inhibit the expression of antiapoptotic protein Bcl-2. AGS synergistic CTX in the treatment of S180 tumour-bearing mice can improve the efficacy and reduce toxicity.

Functional soluble dietary fiber from ginseng residue: Polysaccharide characterization, structure, antioxidant, and enzyme inhibitory activity.

Ginseng (Panax ginseng C.A. Meyer) is the most famous edible Chinese herbal medicine. In the present study, soluble dietary fiber of ginseng (ginseng-SDF, 8.98% content) was extracted from ginseng residue, and its physicochemical characterization, structure, and biological activities were studied. Ginseng-SDF was an acidic heteropolysaccharide (uronic acid, 4.42% content) rich in protein, amino acids, and mineral elements. Glucose was its main monosaccharide composition (58.03%). Ginseng-SDF had a porous microstructure, a typical cellulose I structure and a large number of hydroxyl functional groups. These chemical composition and structural characteristics gave ginseng-SDF a good water solubility (98.56%), oil-holding capacity (OHC) (3.01 g/g), and biological activities, as the antioxidant activity (13.35 µM TE/g, 105.17 µM TE/g, 54.20 µM TE/g for DPPH, ABTs, and FRAP assays, respectively), glucose diffusion retardation index (GDRI, 33.33%-7.43%), and α-amylase/α-glucosidase inhibitory activities (IC50 , 6.70 mg/ml, and 4.89 mg/ml, respectively). The results suggested that ginseng residue is a valuable source of functional dietary fiber, and the ginseng-SDF has a potential use in antioxidant and hypoglycemic foods. PRACTICAL APPLICATIONS: Ginseng has long been popular as a health food in Asia, North America, and Europe. Ginseng residue is rich in polysaccharides, dietary fiber, proteins, and other components, which is also of great research value. However, there are few studies focus on the soluble dietary fiber of ginseng at present. The research shows that ginseng residue is a valuable source of functional dietary fiber. The chemical components and structural characteristics give ginseng-SDF a noteworthy antioxidant activity and enzyme inhibitory activity in vitro. These properties and biological activities indicate that ginseng-SDF has application value in antioxidant and hypoglycemic foods.

Effects of Schisandra chinensis polysaccharides on rats with antibiotic-associated diarrhea.

Schisandra chinensis (S. chinensis), a traditional Chinese medicine (TCM), is comprised of polysaccharides as its main active component. In this study, water-soluble polysaccharides from S. chinensis (WSP) were extracted, and their effects on rats with antibiotic-associated diarrhea were investigated. The rats were treated with lincomycin hydrochloride, followed by saline (natural recovery [NR] group) or WSP (WSP group). The body weight and water intake of rats were analyzed, as well as histological data. Other experiments involving a measurement of cytokine levels, 16s rRNA sequencing analysis of caecal contents, and a measurement of the concentration of short chain fatty acids (SCFAs) were also performed. Compared to rats of the NR group, WSP decreased the infiltration of inflammatory cells into the ileum and colon; decreased the levels of IL-4, IL-17A and TNF-α; increased the serum IL-2 and IL-10 levels; increased the relative abundance of Blautia, Intestinibacter and Lachnospiraceae-UCG-008, but decreased the relative abundance of Ruminococcus-1, Ruminococcaceae-UCG-014 and Erysipelatoclostridium at the genus level; and significantly increased the contents of total SCFAs, acetate and propionate. In conclusion, WSP affected rats with antibiotic-associated diarrhea by improving the ultrastructure of the gut, adjusting cytokine levels and modifying the gut microbial community and SCFAs production.