1.Rectal Administration of Leek and Konjac-derived Extracellular Vesicles Alleviates High-fat Diet-induced Obesity in Mice via Gut Microbiota Modulation
Ya-Ru ZHANG ; Yu-Jia WU ; Cheng-Bang LIANG ; Xin-He YU ; Yan MU ; Yan TAN
Progress in Biochemistry and Biophysics 2026;53(5):1224-1239
ObjectiveObesity, a global chronic metabolic disease, is closely associated with disruptions in lipid metabolism and gut microbiota. Current intervention strategies still have limitations in terms of safety and microecological regulation, necessitating the exploration of novel natural regulatory approaches. Based on the early pathological characteristics of obesity, this study innovatively employs a rectal delivery method alongside a high-fat diet (HFD)-induced obesity model to systematically evaluate the inhibitory effects, safety, and gut microbiota regulation mechanisms of leek-derived and konjac-derived extracellular vesicles on obesity development. By simulating early clinical intervention scenarios, this study aims to explore the preventive potential of plant-derived extracellular vesicles during the initial stages of obesity onset. MethodsExtracellular vesicles from leek and konjac were isolated using ultracentrifugation combined with density gradient centrifugation. Their nanoscale properties were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), and nanoparticle tracking analysis (NTA). Male C57BL/6J mice were randomly divided into four groups: normal control (NC), high-fat diet (HFD), leek-derived extracellular vesicles (LEVs), and konjac-derived extracellular vesicles (KEVs). Beginning simultaneously with HFD feeding, mice in the intervention groups received 20 g/L vesicles rectally every 3 d for 4 weeks. Body mass and body composition were monitored throughout. At endpoint, mouse serum, adipose tissue, and colonic contents were collected. Serum biochemical indices (lipid profile, liver and kidney function, cardiac markers) were assessed to evaluate safety and metabolic efficacy, while 16S rRNA sequencing was employed to analyze gut microbial structure and diversity. ResultsDLS, NTA, and TEM confirmed that both LEVs and KEVs exhibited typical cup-shaped nanostructures with average particle sizes of approximately 284 nm and 223 nm, respectively. LEVs and KEVs treatment significantly suppressed HFD-induced weight gain and elevation of body-fat percentage (P<0.05), and reduced accumulation of abdominal white and epididymal adipose tissue. Serological analyses showed that both vesicles lowered total cholesterol, triglycerides and LDL-cholesterol, and ameliorated liver enzyme profiles (ALT, AST), demonstrating lipid-metabolic regulation and hepatoprotective effects. No hepatic, renal or cardiac dysfunction was observed, indicating favorable safety. Gut microbiota analyses revealed that vesicle intervention partially restored HFD-depleted microbial diversity and reshaped community structure. Notably, LEVs markedly increased the relative abundance of the beneficial taxon Lachnospiraceae at the family level, which is known for producing short-chain fatty acids and enhancing intestinal barrier function. Furthermore, Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) functional prediction suggested that LEVs and KEVs modulated gut microbial functions through distinct mechanisms: LEVs downregulated pathways related to ribosomes and DNA replication while enhancing xenobiotic degradation, whereas KEVs tended to upregulate energy metabolism and protein synthesis toward healthy levels. ConclusionRectally administered LEVs and KEVs exhibit excellent safety and pronounced metabolic benefits during the early phase of obesity, suppressing weight gain, correcting lipid dysregulation, and exerting effects via modulation of gut microbial composition and function. This study provides systematic experimental evidence supporting plant-derived exosome-like vesicles as an early intervention strategy against obesity.
2.Rectal Administration of Leek and Konjac-derived Extracellular Vesicles Alleviates High-fat Diet-induced Obesity in Mice via Gut Microbiota Modulation
Ya-Ru ZHANG ; Yu-Jia WU ; Cheng-Bang LIANG ; Xin-He YU ; Yan MU ; Yan TAN
Progress in Biochemistry and Biophysics 2026;53(5):1224-1239
ObjectiveObesity, a global chronic metabolic disease, is closely associated with disruptions in lipid metabolism and gut microbiota. Current intervention strategies still have limitations in terms of safety and microecological regulation, necessitating the exploration of novel natural regulatory approaches. Based on the early pathological characteristics of obesity, this study innovatively employs a rectal delivery method alongside a high-fat diet (HFD)-induced obesity model to systematically evaluate the inhibitory effects, safety, and gut microbiota regulation mechanisms of leek-derived and konjac-derived extracellular vesicles on obesity development. By simulating early clinical intervention scenarios, this study aims to explore the preventive potential of plant-derived extracellular vesicles during the initial stages of obesity onset. MethodsExtracellular vesicles from leek and konjac were isolated using ultracentrifugation combined with density gradient centrifugation. Their nanoscale properties were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), and nanoparticle tracking analysis (NTA). Male C57BL/6J mice were randomly divided into four groups: normal control (NC), high-fat diet (HFD), leek-derived extracellular vesicles (LEVs), and konjac-derived extracellular vesicles (KEVs). Beginning simultaneously with HFD feeding, mice in the intervention groups received 20 g/L vesicles rectally every 3 d for 4 weeks. Body mass and body composition were monitored throughout. At endpoint, mouse serum, adipose tissue, and colonic contents were collected. Serum biochemical indices (lipid profile, liver and kidney function, cardiac markers) were assessed to evaluate safety and metabolic efficacy, while 16S rRNA sequencing was employed to analyze gut microbial structure and diversity. ResultsDLS, NTA, and TEM confirmed that both LEVs and KEVs exhibited typical cup-shaped nanostructures with average particle sizes of approximately 284 nm and 223 nm, respectively. LEVs and KEVs treatment significantly suppressed HFD-induced weight gain and elevation of body-fat percentage (P<0.05), and reduced accumulation of abdominal white and epididymal adipose tissue. Serological analyses showed that both vesicles lowered total cholesterol, triglycerides and LDL-cholesterol, and ameliorated liver enzyme profiles (ALT, AST), demonstrating lipid-metabolic regulation and hepatoprotective effects. No hepatic, renal or cardiac dysfunction was observed, indicating favorable safety. Gut microbiota analyses revealed that vesicle intervention partially restored HFD-depleted microbial diversity and reshaped community structure. Notably, LEVs markedly increased the relative abundance of the beneficial taxon Lachnospiraceae at the family level, which is known for producing short-chain fatty acids and enhancing intestinal barrier function. Furthermore, Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) functional prediction suggested that LEVs and KEVs modulated gut microbial functions through distinct mechanisms: LEVs downregulated pathways related to ribosomes and DNA replication while enhancing xenobiotic degradation, whereas KEVs tended to upregulate energy metabolism and protein synthesis toward healthy levels. ConclusionRectally administered LEVs and KEVs exhibit excellent safety and pronounced metabolic benefits during the early phase of obesity, suppressing weight gain, correcting lipid dysregulation, and exerting effects via modulation of gut microbial composition and function. This study provides systematic experimental evidence supporting plant-derived exosome-like vesicles as an early intervention strategy against obesity.
3.Phase changes and quantity-quality transfer of raw material, calcined decoction pieces, and standard decoction of Ostreae Concha (Ostrea rivularis).
Hong-Yi ZHANG ; Jing-Wei ZHOU ; Jia-Wen LIU ; Wen-Bo FEI ; Shi-Ru HUANG ; Yu-Mei CHEN ; Chong-Yang LI ; Fei-Fei LI ; Qiao-Ling MA ; Fu WANG ; Yuan HU ; You-Ping LIU ; Shi-Lin CHEN ; Lin CHEN ; Hong-Ping CHEN
China Journal of Chinese Materia Medica 2025;50(5):1209-1223
The phase changes and quantity-quality transfer of 17 batches of Ostreae Concha(Ostrea rivularis) during the raw material-calcined decoction pieces-standard decoction process were analyzed. The content of calcium carbonate(CaCO_3), the main component, was determined by chemical titration, and the extract yield and transfer rate were calculated. The CaCO_3 content in the raw material, calcined decoction pieces, and standard decoction was 94.39%-98.80%, 95.03%-99.22%, and 84.58%-90.47%, respectively. The process of raw material to calcined decoction pieces showed the yield range of 96.85% to 98.55% and the CaCO_3 transfer rate range of 96.92% to 99.27%. The process of calcined decoction pieces to standard decoction showed the extract yield range of 2.86% to 5.48% and the CaCO_3 transfer rate range of 2.59% to 5.13%. The results of X-ray fluorescence(XRF) assay showed that the raw material, calcined decoction pieces, and standard decoction mainly contained Ca, Na, Mg, Si, Br, Cl, Al, Fe, Cr, Mn, and K. The chemometric results showed an increase in the relative content of Cr, Fe, and Si from raw material to calcined decoction pieces and an increase in the relative content of Mg, Al, Br, K, Cl, and Na from calcined decoction pieces to standard decoction. X-ray diffraction(XRD) was employed to establish XRD characteristic patterns of the raw material, calcined decoction pieces, and standard decoction. The XRD results showed that the main phase of all three was calcite, and no transformation of crystalline form or generation of new phase was observed. Fourier transform infrared spectroscopy(FTIR) was employed to establish the FTIR characteristic spectra of the raw material, calcined decoction pieces, and standard decoction. The FTIR results showed that the raw material had internal vibrations of O-H, C-H, C=O, C-O, and CO■ groups. Due to the loss of organic matter components after calcination, no information about the vibrations of C-H, C=O, and C-O groups was observed in the spectra of calcined decoction pieces and standard decoction. In summary, this study elucidated the quantity-quality transfer and phase changes in the raw material-calcined decoction pieces-standard decoction process by determining the CaCO_3 content, calculating the extract yield and transfer rate, and comparing the element changes, FTIR characteristic spectra, and XRD characteristic pattern. The results were reasonable and reliable, laying a foundation for the subsequent process research and quality control of the formula granules of calcined Ostreae Concha(O. rivularis Gould), and providing ideas and methods for the quality control of the whole process of raw material-decoction pieces-standard decoction-formula granules of Ostreae Concha and other testacean traditional Chinese medicine.
Drugs, Chinese Herbal/isolation & purification*
;
Calcium Carbonate/analysis*
;
Quality Control
4.A new perspective on quality control of traditional Chinese medicine based on characteristics of "physical phase structure".
Zhong-Huan QU ; Yan-Jun YANG ; Bing YANG ; Ru-Yu SHI ; Mao-Mao ZHU ; Lu SUN ; Xiao-Bin JIA ; Liang FENG
China Journal of Chinese Materia Medica 2025;50(13):3579-3588
Quality control is a key link in the modernization process of traditional Chinese medicine(TCM). Studies have shown that the effects of active components in TCM depend on not only their chemical composition but also their suitable physical forms and states. The physical phase structures, such as micelles, vesicles, gels, and nanoparticles, can improve the solubility, delivery efficiency, and targeting precision of active components. These structures significantly enhance the pharmacological activity while reducing the toxicity and side effects, demonstrating functional activity surpassing that of active components and highlighting the key effects of "structures" on "functions" of active components. Taking the physical phase structure as a breakthrough point, this paper outlines the common types of TCM physical phase structures. Furthermore, this paper explores how to realize the quality upgrading of TCM through the precise regulation of physical phase structures based on the current applications and potential of TCM physical phase structures in processing to increase the efficacy and reduce the toxicity, compounding and decocting processes, drug delivery systems, and quality control, aiming to provide novel insights for the future quality control of TCM.
Quality Control
;
Drugs, Chinese Herbal/standards*
;
Medicine, Chinese Traditional/standards*
;
Humans
;
Drug Delivery Systems
5.Placebo response in sham acupuncture therapy trials for simple obesity: A systematic review and meta-analysis.
Ke-Jia LIU ; Rui-Min JIAO ; Jing JI ; Wei-Wei YAO ; Chao-Ru HAN ; Xin-Yu ZHAO ; Jing-Jie ZHAO
Journal of Integrative Medicine 2025;23(3):264-273
BACKGROUND:
Acupuncture has shown potential therapeutic benefits for individuals with simple obesity. However, some researchers argue that some of the effectiveness of acupuncture may be due to the placebo response.
OBJECTIVE:
To understand the placebo response of acupuncture treatment in simple obesity, a systematic review and meta-analysis was designed based on the comparison between sham acupuncture before and after treatment.
SEARCH STRATEGY:
Eight databases (PubMed, Web of Science, Cochrane Library, Embase, China National Knowledge Infrastructure, Wanfang Database, China Biology Medicine Database, and Chinese Scientific Journals Database) were searched from inception to August 1, 2023. The MeSH search terms comprised obesity and acupuncture.
INCLUSION CRITERIA:
Randomized controlled trials (RCTs) using sham or placebo acupuncture as a control in treating obesity were enrolled.
DATA EXTRACTION AND ANALYSIS:
Two researchers independently extracted data, and the results were cross-checked after completion. Each RCT's detailed sham/placebo acupuncture treatment protocol was assessed according to the SHam Acupuncture REporting guidelines. The revised Cochrane risk-of-bias tool for randomized trials and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system were used to determine the risk of bias and quality of evidence, respectively. Body mass index (BMI) was defined as the primary outcome. Anthropometric parameters and laboratory test parameters related to obesity were defined as secondary outcomes. We used standardized mean difference (SMD) with 95% confidence interval (CI) to calculate treatment effects of outcomes.
RESULTS:
Fifteen RCTs with a total of 1250 patients were included. The BMI significantly decreased after treatment in the sham acupuncture group compared to baseline (SMD 0.37, 95% CI 0.09-0.66; I2 = 81%, random model; P < 0.01). Treatment duration (P = 0.02) and other interventions significantly impacted the placebo response rate (P = 0.00).
CONCLUSION
The placebo response of sham acupuncture was strong in the RCTs for simple obesity, and the effect sizes differed between various outcomes. The treatment duration and other interventions emerged as potential influencing factors for the placebo response of sham acupuncture. Please cite this article as: Liu KJ, Jiao RM, Ji J, Yao WW, Han CR, Zhao XY, Zhao JJ. Placebo response in sham acupuncture therapy trials for simple obesity: a systematic review and meta-analysis. J Integr Med. 2025; 23(3): 264-273.
Humans
;
Acupuncture Therapy/methods*
;
Obesity/therapy*
;
Placebo Effect
;
Placebos
;
Randomized Controlled Trials as Topic
6.Novel biallelic MCMDC2 variants were associated with meiotic arrest and nonobstructive azoospermia.
Hao-Wei BAI ; Na LI ; Yu-Xiang ZHANG ; Jia-Qiang LUO ; Ru-Hui TIAN ; Peng LI ; Yu-Hua HUANG ; Fu-Rong BAI ; Cun-Zhong DENG ; Fu-Jun ZHAO ; Ren MO ; Ning CHI ; Yu-Chuan ZHOU ; Zheng LI ; Chen-Cheng YAO ; Er-Lei ZHI
Asian Journal of Andrology 2025;27(2):268-275
Nonobstructive azoospermia (NOA), one of the most severe types of male infertility, etiology often remains unclear in most cases. Therefore, this study aimed to detect four biallelic detrimental variants (0.5%) in the minichromosome maintenance domain containing 2 ( MCMDC2 ) genes in 768 NOA patients by whole-exome sequencing (WES). Hematoxylin and eosin (H&E) demonstrated that MCMDC2 deleterious variants caused meiotic arrest in three patients (c.1360G>T, c.1956G>T, and c.685C>T) and hypospermatogenesis in one patient (c.94G>T), as further confirmed through immunofluorescence (IF) staining. The single-cell RNA sequencing data indicated that MCMDC2 was substantially expressed during spermatogenesis. The variants were confirmed as deleterious and responsible for patient infertility through bioinformatics and in vitro experimental analyses. The results revealed four MCMDC2 variants related to NOA, which contributes to the current perception of the function of MCMDC2 in male fertility and presents new perspectives on the genetic etiology of NOA.
Humans
;
Male
;
Azoospermia/genetics*
;
Meiosis/genetics*
;
Spermatogenesis/genetics*
;
Adult
;
Exome Sequencing
;
Microtubule-Associated Proteins/genetics*
;
Alleles
;
Infertility, Male/genetics*
7.Mediating effect of sleep duration between depression symptoms and myopia in middle school students.
Wei DU ; Xu-Xiang YANG ; Ru-Shuang ZENG ; Chun-Yao ZHAO ; Zhi-Peng XIANG ; Yuan-Chun LI ; Jie-Song WANG ; Xiao-Hong SU ; Xiao LU ; Yu LI ; Jing WEN ; Dang HAN ; Qun DU ; Jia HE
Chinese Journal of Contemporary Pediatrics 2025;27(3):359-365
OBJECTIVES:
To explore the mediating role of sleep duration in the relationship between depression symptoms and myopia among middle school students.
METHODS:
This study was a cross-sectional research conducted using a stratified cluster random sampling method. A total of 1 728 middle school students were selected from two junior high schools and two senior high schools in certain urban areas and farms of the Xinjiang Production and Construction Corps. Questionnaire surveys and vision tests were conducted among the students. Spearman analysis was used to analyze the correlation between depression symptoms, sleep duration, and myopia. The Bootstrap method was employed to investigate the mediating effect of sleep duration between depression symptoms and myopia.
RESULTS:
The prevalence of myopia in the overall population was 74.02% (1 279/1 728), with an average sleep duration of (7.6±1.0) hours. The rate of insufficient sleep was 83.62% (1 445/1 728), and the proportion of students exhibiting depression symptoms was 25.29% (437/1 728). Correlation analysis showed significant negative correlations between visual acuity in both eyes and sleep duration with depressive emotions as measured by the Center for Epidemiologic Studies Depression Scale (with correlation coefficients of -0.064, -0.084, and -0.199 respectively; P<0.01), as well as with somatic symptoms and activities (with correlation coefficients of -0.104, -0.124, and -0.233 respectively; P<0.01) and interpersonal relationships (with correlation coefficients of -0.052, -0.059, and -0.071 respectively; P<0.05). The correlation coefficients for left and right eye visual acuity and sleep duration were 0.206 and 0.211 respectively (P<0.001). Sleep duration exhibited a mediating effect between depression symptoms and myopia (indirect effect=0.056, 95%CI: 0.029-0.088), with the mediating effect value for females (indirect effect=0.066, 95%CI: 0.024-0.119) being higher than that for males (indirect effect=0.042, 95%CI: 0.011-0.081).
CONCLUSIONS
Sleep duration serves as a partial mediator between depression symptoms and myopia in middle school students.
Humans
;
Myopia/etiology*
;
Male
;
Female
;
Depression/physiopathology*
;
Cross-Sectional Studies
;
Sleep
;
Adolescent
;
Students
;
Child
;
Time Factors
;
Sleep Duration
8.Efficacy and Safety of Juan Bi Pill with Add-on Methotrexate in Active Rheumatoid Arthritis: A 48-Week, Multicentre, Randomized, Double-Blind, Placebo-Controlled Trial.
Qing-Yun JIA ; Yi-Ru WANG ; Da-Wei SUN ; Jian-Chun MAO ; Luan XUE ; Xiao-Hua GU ; Xiang YU ; Xue-Mei PIAO ; Hao XU ; Qian-Qian LIANG
Chinese journal of integrative medicine 2025;31(2):99-107
OBJECTIVE:
To explore the efficacy and safety of Juan Bi Pill (JBP) in treatment of active rheumatoid arthritis (RA).
METHODS:
From February 2017 to May 2018, 115 participants from 4 centers were randomly divided into JBP group (57 cases) and placebo group (58 cases) in a 1:1 ratio using a random number table method. Participants received a dose of JBP (4 g, twice a day, orally) combined with methotrexate (MTX, 10 mg per week) or placebo (4 g, twice a day, orally) combined with MTX for 12 weeks. Participants were required with follow-up visits at 24 and 48 weeks, attending 7 assessment visits. Participants were undergo disease activity assessment 7 times (at baseline and 2, 4, 8, 12, 24, 48 weeks) and safety assessments 6 times (at baseline and 4, 8, 12, 24, 48 weeks). The primary endpoint was 28-joint Disease Activity Score (DAS28-ESR and DAS28-CRP). The secondary endpoints included American College of Rheumatology (ACR) criteria for 20% and 50% improvement (ACR20/50), Health Assessment Questionnaire Disability Index (HAQ-DI), clinical disease activity index (CDAI), visual analog scale (VAS), Short Form-36 (SF-36) score, Medial Outcomes Study (MOS) sleep scale score, serum erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), tender joint count, swollen joint count, and morning stiffness. The adverse reactions were observed during the treatment.
RESULTS:
After 12 weeks of treatment, DAS28-ESR and DAS28-CRP scores in both groups were lower than before treatment (both P<0.01), while the remission rate of DAS28-ESR and DAS28-CRP and low disease activity of JBP group were higher than those in the placebo group (both P<0.01). JBP demonstrated better efficacy on ACR20 and ACR50 compliance rate at 12 and 48 weeks comparing to placebo (all P<0.05). The CDAI and HAQ-DI score, pain VAS and global VAS change of RA patients and physicians, the serum ESR and CRP levels, and the number of tenderness and swelling joints were lower than before treatment at 4, 8, 12, 24, 48 weeks in both groups (P<0.05 or P<0.01), while the reduction of above indices in the JBP group was more obvious than those in the placebo group at 12 weeks (ESR and CRP, both P<0.05) or at 12 and 48 weeks (all P<0.01). There was no difference in adverse reactions between the 2 groups during treatment (P=0.75).
CONCLUSION
JBP combined with MTX could effectively reduce disease activity in patients with RA in active stage, reduce the symptoms of arthritis, and improve the quality of life, while ensuring safety, reliability, and fewer adverse effects. (Trial Registration: ClinicalTrials.gov, No. NCT02885597).
Humans
;
Arthritis, Rheumatoid/drug therapy*
;
Methotrexate/adverse effects*
;
Female
;
Double-Blind Method
;
Male
;
Middle Aged
;
Treatment Outcome
;
Drugs, Chinese Herbal/adverse effects*
;
Drug Therapy, Combination
;
Adult
;
Antirheumatic Agents/adverse effects*
;
Aged
9.Design, synthesis, and antitumor activity of novel thioheterocyclic nucleoside derivatives by suppressing the c-MYC pathway.
Xian-Jia LI ; Ke-Xin HUANG ; Ke-Xin WANG ; Ru LIU ; Dong-Chao WANG ; Yu-Ru LIANG ; Er-Jun HAO ; Yang WANG ; Hai-Ming GUO
Acta Pharmaceutica Sinica B 2025;15(7):3685-3707
Eightly-four novel thioheterocyclic nucleoside derivatives were designed, synthesized, and evaluated for antitumor activity in vitro and in vivo. Most of the compounds inhibited the growth of HCT116 and HeLa cancer cells in vitro, among them 33a and 36b exhibited potent activity against HCT116 cells (IC50 = 0.27 and 0.49 μmol/L, respectively). Both compounds 33a and 36b inhibited cell metastasis, arrested the cell cycle in the G2/M phase, and induced apoptosis in vitro. Mechanistic studies revealed that 33a and 36b increased ROS levels, led to DNA damage, ER stress, and mitochondrial dysfunction, and inhibited autophagy in HCT116 cells. Biological information analysis, RNA-sequencing, Gene Set Enrichment Analysis (GSEA), drug affinity responsive target stability (DARTS) assay, cellular thermal shift assay (CETSA), and SPR experiments identified that compounds 33a and 36b showed antitumor activity by suppressing the c-MYC pathway. c-MYC silencing assays indicated that c-MYC proteins participated in 33a-mediated anticancer activities in HCT116 cells. More importantly, compound 33a presented favorable pharmacokinetic properties in mice (T 1/2 = 6.8 h) and showed significant antitumor efficacy in vivo without obvious toxicity, showing promising potential for further clinical development.
10.Label-free Fluorescence Probe Based on Primer Exchange Reaction for High Sensitivity Detection of Apurinic/Apyrimidinic Endonuclease 1
Yun-Hua WANG ; Le-Ru WANG ; Li-Gai YANG ; Jia-Zheng CHEN ; Yu-Run DU ; Jia-Hui HOU ; Xiang ZHAI ; Xu-Hua ZHAO ; Bao-Feng YU
Chinese Journal of Analytical Chemistry 2025;53(3):464-471
Apurinic/apyrimidinic endonuclease 1(APE 1)is a multifunctional protein that plays important roles in DNA repair and regulation of gene expression.Because APE 1 is overexpressed in various cancers,it can serve as a cancer biomarker for aiding clinical diagnosis,guiding therapy,and monitoring prognosis.On this basis,a label-free fluorescent probe was designed based on the primer exchange reaction(PER)strategy for highly sensitive detection of APE 1 activity.In the absence of APE 1,the structure of catalytic hairpin(HP)was stable and could not form G-quadruplex.Therefore,the background fluorescence of this sensing system was very low due to the dissociation of thioflavin T(ThT).In the presence of APE 1,the apurinic/apyrimidinic(AP)site of HP was cleaved by APE 1 and a short nucleic acid fragment that acted as a primer to initiate PER was generated.After PER reaction,a large number of G-quadruplex were produced,which could specifically bind with ThT and resulted in significant increase of fluorescence signal.The combination of low background design of HP and PER amplification made this biosensor had high sensitivity with a detection limit(3σ)of 0.0008 U/mL.Furthermore,the primer sequence was directly generated by the cleavage of APE 1 without additional addition,which not only increased the specificity of the reaction,but also simplified the experiment procedure.Moreover,the use of label-free fluorescence signal reduced the cost of the experiment,and realized rapid detection of APE 1.Finally,this sensor was used to detect APE 1 in human serum samples with spiked recoveries of 91%-104%,proving great potential in study of biological enzyme.

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