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Berberine (BBR), as a natural isoquinoline alkaloid, has demonstrated various pharmacological activities, and is widely applied in the treatment of diseases. The quantitative analysis of BBR is important for pharmacological studies and clinical applications. In this work, utilizing the specific interaction between BBR and triplex DNA, a sensitive and selective fluorescent detecting method was established with DNA-templated silver nanoclusters (DNA-AgNCs). After binding with the triplex structure in the template of DNA-AgNCs, BBR quenched the fluorescence of DNA-AgNCs and formed BBR-triplex complex with yellow-green fluorescence. The ratiometric fluorescence signal showed a linear relationship with BBR concentration in a range from 10 nM to 1000 nM, with a detection limit of 10 nM. Our method exhibited excellent sensitivity and selectivity, and was further applied in BBR detection in real samples.
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Berberina , ADN , Nanopartículas del Metal , Plata , Espectrometría de Fluorescencia , Berberina/química , Berberina/análisis , Plata/química , Nanopartículas del Metal/química , ADN/química , ADN/análisis , Espectrometría de Fluorescencia/métodos , Fluorescencia , Límite de Detección , HumanosRESUMEN
Background: Trimethylamine-N-oxide (TMAO) is produced by hepatic flavin-containing monooxygenase 3 (FMO3) from trimethylamine (TMA). High TMAO level is a biomarker of cardiovascular diseases and metabolic disorders, and it also affects periodontitis through interactions with the gastrointestinal microbiome. While recent findings indicate that periodontitis may alter systemic TMAO levels, the specific mechanisms linking these changes and particular oral pathogens require further clarification. Methods: In this study, we established a C57BL/6J male mouse model by orally administering Porphyromonas gingivalis (P. gingivalis, Pg), Fusobacterium nucleatum (F. nucleatum, Fn), Streptococcus mutans (S. mutans, Sm) and PBS was used as a control. We conducted LC-MS/MS analysis to quantify the concentrations of TMAO and its precursors in the plasma and cecal contents of mice. The diversity and composition of the gut microbiome were analyzed using 16S rRNA sequencing. TMAO-related lipid metabolism and enzymes in the intestines and liver were assessed by qPCR and ELISA methods. We further explored the effect of Pg on FMO3 expression and lipid molecules in HepG2 cells by stimulating the cells with Pg-LPS in vitro. Results: The three oral pathogenic bacteria were orally administered to the mice for 5 weeks. The Pg group showed a marked increase in plasma TMAO, betaine, and creatinine levels, whereas no significant differences were observed in the gut TMAO level among the four groups. Further analysis showed similar diversity and composition in the gut microbiomes of both the Pg and Fn groups, which were different from the Sm and control groups. The profiles of TMA-TMAO pathway-related genera and gut enzymes were not significantly different among all groups. The Pg group showed significantly higher liver FMO3 levels and elevated lipid factors (IL-6, TG, TC, and NEFA) in contrast to the other groups. In vitro experiments confirmed that stimulation of HepG2 cells with Pg-LPS upregulated the expression of FMO3 and increased the lipid factors TC, TG, and IL-6. Conclusion: This study conclusively demonstrates that Pg, compared to Fn and Sm, plays a critical role in elevating plasma TMAO levels and significantly influences the TMA-TMAO pathway, primarily by modulating the expression of hepatic FMO3 and directly impacting hepatic lipid metabolism.
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Microbioma Gastrointestinal , Metilaminas , Ratones Endogámicos C57BL , Oxigenasas , Porphyromonas gingivalis , Animales , Masculino , Metilaminas/metabolismo , Metilaminas/sangre , Humanos , Ratones , Oxigenasas/metabolismo , Porphyromonas gingivalis/metabolismo , Fusobacterium nucleatum/metabolismo , Redes y Vías Metabólicas , Células Hep G2 , Metabolismo de los Lípidos , Modelos Animales de Enfermedad , Periodontitis/microbiología , Periodontitis/metabolismo , Hígado/metabolismo , ARN Ribosómico 16S/genética , Espectrometría de Masas en Tándem , Boca/microbiologíaRESUMEN
The morphology and function of the cerebellum are associated with various developmental disorders and healthy aging. Changes in cerebellar morphology during the aging process have been extensively investigated, with most studies focusing on changes in cerebellar regional volume. The volumetric method has been used to quantitatively demonstrate the decrease in the cerebellar volume with age, but it has certain limitations in visually presenting the morphological changes of cerebellar atrophy from a three-dimensional perspective. Thus, we comprehensively described cerebellar morphological changes during aging through volume measurements of subregions and shape analysis. This study included 553 healthy participants aged 20-80 years. A novel cerebellar localized segmentation algorithm based on convolutional neural networks was utilized to analyze the volume of subregions, followed by shape analysis for localized atrophy assessment based on the cerebellar thickness. The results indicated that out of the 28 subregions in the absolute volume of the cerebellum, 15 exhibited significant aging trends, and 16 exhibited significant sex differences. Regarding the analysis of relative volume, only 11 out of the 28 subregions of the cerebellum exhibited significant aging trends, and 4 exhibited significant sex differences. The results of the shape analysis revealed region-specific atrophy of the cerebellum with increasing age. Regions displaying more significant atrophy were predominantly located in the vermis, the lateral portions of bilateral cerebellar hemispheres, lobules I-III, and the medial portions of the posterior lobe. This atrophy differed between sexes. Men exhibited slightly more severe atrophy than women in most of the cerebellar regions. Our study provides a comprehensive perspective for observing cerebellar atrophy during the aging process.
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BACKGROUND: Among older adults, type 2 diabetes mellitus (T2DM) is widely recognized as one of the most prevalent diseases. Diabetic nephropathy (DN) is a frequent complication of DM, mainly characterized by renal microvascular damage. Early detection, aggressive prevention, and cure of DN are key to improving prognosis. Establishing a diagnostic and predictive model for DN is crucial in auxiliary diagnosis. AIM: To investigate the factors that impact T2DM complicated with DN and utilize this information to develop a predictive model. METHODS: The clinical data of 210 patients diagnosed with T2DM and admitted to the First People's Hospital of Wenling between August 2019 and August 2022 were retrospectively analyzed. According to whether the patients had DN, they were divided into the DN group (complicated with DN) and the non-DN group (without DN). Multivariate logistic regression analysis was used to explore factors affecting DN in patients with T2DM. The data were randomly split into a training set (n = 147) and a test set (n = 63) in a 7:3 ratio using a random function. The training set was used to construct the nomogram, decision tree, and random forest models, and the test set was used to evaluate the prediction performance of the model by comparing the sensitivity, specificity, accuracy, recall, precision, and area under the receiver operating characteristic curve. RESULTS: Among the 210 patients with T2DM, 74 (35.34%) had DN. The validation dataset showed that the accuracies of the nomogram, decision tree, and random forest models in predicting DN in patients with T2DM were 0.746, 0.714, and 0.730, respectively. The sensitivities were 0.710, 0.710, and 0.806, respectively; the specificities were 0.844, 0.875, and 0.844, respectively; the area under the receiver operating characteristic curve (AUC) of the patients were 0.811, 0.735, and 0.850, respectively. The Delong test results revealed that the AUC values of the decision tree model were lower than those of the random forest and nomogram models (P < 0.05), whereas the difference in AUC values of the random forest and column-line graph models was not statistically significant (P > 0.05). CONCLUSION: Among the three prediction models, random forest performs best and can help identify patients with T2DM at high risk of DN.
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BACKGROUND: Bone marrow mesenchymal stem cell (BMSCs) -based therapies represent a promising treatment for neurological disorders. However, therapeutic effects and mechanisms of BMSCs transplantation for radiation-induced brain injury (RIBI) have not been fully disclosed. In this article, we explored the functions of BMSCs transplantation on RIBI and investigated the protective effects of BMSCS on hippocampal neurons in RIBI as well as the related molecular mechanisms. MATERIALS AND METHODS: 6-8 weeks-old rats were used to build a RIBI model. Rats in BMSC group were treated with a 3 × 106 BMSCs injection through the tail vein on the 1st day and 8th day after irradiation; rats in both control and RIBI groups were injected with an equivalent volume of physiological saline for comparisons. The Morris water maze was applied to detect the variations in cognitive function after RIBI. MRS was performed to test changes in NAA/Cr, indicating neuronal apoptosis after RIBI. TUNEL was conducted to detect apoptosis of rat hippocampal neurons, and HE staining was carried out to show pathological variations in the hippocampal region of rats. Protein levels of PI3K, P-PI3K, AKT, P-AKT, Bcl-2, and Bax proteins of rats in the hippocampal area were all determined by Western blot. RESULTS: Cognitive function was reduced and hippocampal neurons underwent apoptosis in the rats of the RIBI group, and cognitive abilities, histopathological alterations, and apoptosis of hippocampal neurons were significantly improved after BMSCs treatment; the expression of PI3K, P-PI3K, AKT, P-AKT, and Bcl-2 proteins, in the hippocampal region of the rat, was up-regulated, and Bax proteins were down-regulated. CONCLUSIONS: BMCSs can inhibit hippocampal neuronal apoptosis in RIBI, and the mechanism may be associated with the up-regulation of Bcl-2 and down-regulation of Bax by the PI3K/AKT signaling pathway.
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Lesiones Encefálicas , Células Madre Mesenquimatosas , Ratas , Animales , Proteínas Proto-Oncogénicas c-akt/metabolismo , Proteína X Asociada a bcl-2/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Ratas Sprague-Dawley , Transducción de Señal , Apoptosis , Lesiones Encefálicas/metabolismo , Hipocampo/metabolismo , Células Madre Mesenquimatosas/metabolismoRESUMEN
The repeat expansions are the main genetic cause of various neurodegeneration diseases. More than ten kinds of repeat sequences with different lengths, locations, and structures have been confirmed in the past two decades. G-rich repeat sequences, such as CGG and GGGGCC, are reported to form functional G-quadruplexes, participating in many important bioprocesses. In this review, we conducted an overview concerning the contribution of G-quadruplex in repeat expansion disorders and summarized related mechanisms in current pathological studies, including the increasing genetic instabilities in replication and transcription, the toxic RNA foci formed in neurons, and the loss/gain function of proteins and peptides. Furthermore, novel strategies targeting G-quadruplex repeats were developed based on the understanding of disease mechanism. Small molecules and proteins binding to G-quadruplex in repeat expansions were investigated to protect neurons from dysfunction and delay the progression of neurodegeneration. In addition, the effects of environment on the stability of G-quadruplex were discussed, which might be critical factors in the pathological study of repeat expansion disorders.
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Esclerosis Amiotrófica Lateral , G-Cuádruplex , Humanos , Esclerosis Amiotrófica Lateral/metabolismo , Proteínas/química , Péptidos/genética , Secuencias Repetitivas de Ácidos NucleicosRESUMEN
Objective:To evaluate the clinical and echocardiographic characteristics of valvular involvement in SLE patients and its predictive value for valvular outcome.Methods:A retrospective study included 58 adult SLE patients with valvular involvement diagnosed for the first time by echocardiography in the First Affiliated Hospital of Wenzhou Medical University. According to gender and age, 1∶2 SLE patients without valvular involvement were selected as the control group. Clinical and echocardiographic data within 24 hours after initial admission were collected. The predictive factors were analyzed using cox parametric regression analysis.Results:①Among 58 patients,significant valve lesions were detected by echocardiography in 50 and presented as valve thickening with regurgitation. The mitral valve was the most commonly affected, followed by the aortic valves. ②Compared with the non-valvular involvement group, the percent of CRP, SLC-R, IgA、aCL-IgG were higher in the valvular involvement group [CRP:60.3% vs 30.4%, χ2=10.54, P=0.001; SLC-R: 63.8% vs 19.8%, χ2=33.08, P<0.001; IgA:27.6% vs 22.4%, χ2=16.04, P<0.001; aCL-IgG: 27.6% vs 2.6%, χ2=24.84, P<0.001]. ③Cox parametric regression analysis showed that CRP [ HR (95% CI)=2.641(1.499, 4.654), P=0.001,SLC-R HR(95% CI)=3.234(11.776, 5.888), P<0.001], and aCL-IgG[ HR(95% CI)=2.166 (1.148, 4.087) , P=0.017] were independent predictors of valvular involvement. Conclusion:SLE patients with increased levels of CRP、SLC-R、IgA and aCL-IgG have a high risk of valvular involvement. CRP、SLC-R and aCL-IgG are independent predictors of valvular involvement.
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Objective To investigate the value of echocardiography in assessing right ventricular function of primary light-chain amyloidosis(AL)-cardiac amyloidosis(CA)patients.Methods A total of 25 patients biopsy diagnosed as AL-CA,who were admitted to the First Affiliated Hospital of Wenzhou Medical University from January 2018 to December 2021,were enrolled in this study as amyloidosis group.And 25 heathy volunteers were set as control group.The routine right ventricular morphology and functional parameters were acquired by standard echocardiography.Right ventricular global longitudinal strain(RVGLS)and right ventricular free wall longitudinal strain(RVfwLS)were obtained by two-dimensional speckle tracking imagine.Tricuspid annular plane systolic excursion(TAPSE)/pulmonary artery systolic pressure(PASP),RVGLS/PASP,RVfwLS/PASP ratio were calculated as the noninvasively parameters of right ventricular-pulmonary artery coupling.Results ①Compared with control group,patients in amyloidosis group showed significantly larger right heart size,and significantly thicker right ventricular free wall[(7.16±1.84)mm vs.(3.76±0.66)mm],the difference was statistically significant(P<0.001).②Compared with control group,RVGLS[(17.43±2.45)%vs.(23.22±3.73)%]and RVfwLS[(18.44±2.10)%vs.(22.62±3.64)%]were significantly impaired in amyloidosis group,the difference was statistically significant(P<0.001).The ratios of TAPSE/PASP,RVGLS/PASP,RVfwLS/PASP were found to be lower in amyloidosis group,the difference was statistically significant(P<0.001).③TAPSE/PASP showed mild correlations with N-terminal brain natriuretic peptide precursor(NT-proBNP),highly sensitive T cardiac troponin(hs-TNT)(r=0.45 and 0.40)there were statistically significant(P<0.05).Conclusion Echocardiography can effectively evaluate the right heart function impairment in AL-CA patients,providing valuable information for a deeper understanding of the pathological and physiological mechanisms of the disease.
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The chronic infection with hepatitis B virus (HBV) is an important health problem that affects millions of people worldwide. Current therapies for HBV always suffer from a poor response rate, common side effects, and the need for lifelong treatment. Novel therapeutic targets are expected. Interestingly, non-canonical structures of nucleic acids play crucial roles in the regulation of gene expression. Especially the formation of G-quadruplexes (G4s) in G-rich strands has been demonstrated to affect many bioprocesses including replication, transcription, and translation, showing great potential as targets in anticancer and antiviral therapies. In this review, we summarize recent antiviral studies about G4s and discuss the potential roles of G4 structures in antiviral therapy for HBV.
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G-Cuádruplex , Humanos , Virus de la Hepatitis B/genética , Antivirales/uso terapéutico , Antivirales/químicaRESUMEN
Ginsenoside compound K (CK) is one of the major metabolites of the bioactive ingredients in Panax ginseng, which presents excellent bioactivity and regulates the expression of important proteins. In this work, the effects of CK on G-quadruplexes (G4s) were quantitatively analyzed in the presence and absence of their complementary sequences. CK was demonstrated to facilitate the formation of G4s, and increase the quantity of G4s in the competition with duplex. Thermodynamic experiments suggested that the electrostatic interactions were important for G4 stabilization by CK. CK was further found to regulate the transcription of G4-containing templates, reduce full-length transcripts, and decrease the transcription efficiency. Our results provide new evidence for the pharmacological study of ginsenosides at the gene level.
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G-Cuádruplex/efectos de los fármacos , Ginsenósidos/farmacología , Línea Celular , Ginsenósidos/química , Humanos , Modelos Moleculares , Panax/química , Termodinámica , Transcripción Genética/efectos de los fármacosRESUMEN
The regulatory mechanisms of the processes of RNA accumulation were examined from a chemical perspective in repeat-expansion disorders, which induce cytotoxicity and cause neurodegenerative diseases. We found that the accumulation, including production, gelation, and sedimentation, of RNA repeats transcribed from repeat expansions related to neurodegenerative diseases was greatly accelerated by G-quadruplex-forming RNA repeats, although no acceleration was induced by hairpin-forming RNA repeats. We also investigated the relationship between accumulation and physical solution properties, such as viscosity and water activity, and found that RNA accumulation was promoted through a decrease in the dielectric constant. Importantly, we found that the RNA accumulation required RNA G-quadruplexes and was promoted by changes in the dielectric property of the cell induced by an ion channel inhibitor. Our study is the first to show that the accumulation processes that induce toxicity in cells can be controlled via electrostatic interactions in the RNA G-quadruplex; thus, these can form the basis of guidelines for the chemical control of cell toxins.
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G-Cuádruplex , Guanina/metabolismo , ARN/metabolismo , Secuencias Repetitivas de Ácidos Nucleicos , Guanina/química , Humanos , Microscopía Fluorescente , Imagen Óptica , ARN/química , Células Tumorales CultivadasRESUMEN
The properties of non-canonical DNA structures, like G-quadruplexes and triplexes, change under cell-mimicking molecular crowding conditions relative to dilute aqueous solutions. The analysis of environmental effects on their stability is crucial since they play important roles in gene expression and regulation. In this study, three intramolecular and intermolecular triplex-forming sequences of different C+*G-C triplet content (*: Hoogsteen base pair; - : Watson-Crick base pair) were designed and their stability measured in the absence and presence of a crowding agent with different K+ concentrations. In dilute solution, the stability of the triplexes was reduced by decreasing the concentration of KCl. This reduction became smaller as the number of C+*G-C triplets increased. Under molecular crowding conditions, Watson-Crick base pairs and Hoogsteen base pairs were destabilized and stabilized, respectively. Interestingly, with lower KCl concentrations (≤1 M), the destabilization of the triplexes due to reduction of KCl concentration was significantly smaller than in dilute solutions. In addition, the C+*G-C content had greater influence on triplex stability under molecular crowding conditions. Our work provides quantitative information about the effects of K+ concentration on triplex stability under molecular crowding conditions and should further our understanding of the function and regulation of triplexes in bioprocesses.
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ADN/química , Potasio/farmacología , Dicroismo Circular , ADN/efectos de los fármacos , Modelos Moleculares , Peso Molecular , Conformación de Ácido Nucleico/efectos de los fármacos , Polietilenglicoles/farmacología , Cloruro de Potasio/farmacologíaRESUMEN
Nucleic acid stability and structure, which are crucial to the properties of fluorescent DNA-templated silver nanoclusters (DNA-Ag NCs), significantly change in ionic liquids. In this work, our purpose was to study DNA-Ag NCs in a buffer containing the hydrated ionic liquid of choline dihydrogen phosphate (choline dhp) to improve fluorescence for application in DNA detection. Due to the stabilisation of an i-motif structure by the choline cation, a unique fluorescence emission-that was not seen in an aqueous buffer-was observed in choline dhp and remained stable for more than 30 days. A DNA-Ag NCs probe was designed to have greater fluorescence intensity in choline dhp in the presence of a target DNA. A turn-on sensing platform in choline dhp was built for the detection of the BRCA1 gene, which is related to familial breast and ovarian cancers. This platform showed better sensitivity and selectivity in distinguishing a target sequence from a mutant sequence in choline dhp than in the aqueous buffer. Our study provides new evidence regarding the effects of structure on properties of fluorescent DNA-Ag NCs and expands the applications of fluorescent DNA-Ag NCs in an ionic liquid because of improved sensitivity and selectivity.
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Líquidos Iónicos/química , Nanopartículas del Metal/química , Plata/química , Proteína BRCA1/química , Fluorescencia , Fosforilcolina/química , Espectrometría de FluorescenciaRESUMEN
The trinucleotide repeat d(CXG) (Xâ¯=â¯A, C, G or T) is the most common sequence causing repeat expansion disorders. The formation of non-canonical structures, such as hairpin structures with X-X mismatches, has been proposed to affect gene expression and regulation, which are important in pathological studies of these devastating neurological diseases. However, little information is available regarding the thermodynamics of the repeat sequence under crowded cellular conditions where many non-canonical structures such as G-quadruplexes are highly stabilized, while duplexes are destabilised. In this study, we investigated the different stabilities of X-X mismatches in the context of internal d(CXG) self-complementary sequences in an environment with a high concentration of cosolutes to mimic the crowding conditions in cells. The stabilities of full-matched duplexes and duplexes with A-A, G-G, and T-T mismatched base pairs under molecular crowding conditions were notably decreased compared to under dilute conditions. However, the stability of the DNA duplex with a C-C mismatch base pair was only slightly destabilised. Investigating different stabilities of X-X mismatches in d(CXG) sequences is important for improving our understanding of the formation and transition of multiple non-canonical structures in trinucleotide repeat diseases, and may provide insights for pathological studies and drug development.
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Disparidad de Par Base , ADN/genética , Repeticiones de Trinucleótidos , Secuencia de Bases , ADN/química , G-Cuádruplex , Conformación de Ácido Nucleico , Polietilenglicoles/química , TermodinámicaRESUMEN
BACKGROUND: Hypodermin A (HA) is a serine esterase that degrades complement, a key element of the innate immune system. Immunosuppressive properties of HA have previously been studied in vitro. However, such properties have not been fully demonstrated in vivo. The aim of this study was to evaluate the effect of HA in inhibiting allograft rejection in an HA transgenic mouse model. METHODS: FVB (HA transgenic mice or wild-type mice) to BALB/c mice skin transplantation model were used. Skin grafts were analyzed by histology, immunohistochemistry, and Western blotting. RESULTS: HA overexpression resulted in significantly prolonged skin allograft survival. Histologic changes in the skin allografts paralleled the gross appearance of rejection. ELISA and Western blotting showed that HA significantly reduced the content of complement C3 and C9 in HA skin allografts. The expressions of CD4, B7-2, and MHC class II were all significantly suppressed in HA skin allografts compared with the control group. CONCLUSIONS: These findings suggest that HA effectively prolongs skin allograft survival. The study results provide insight into a promising strategy to improve the survival of grafts in humans.
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Terapia Genética/métodos , Rechazo de Injerto/prevención & control , Supervivencia de Injerto/inmunología , Serina Endopeptidasas/inmunología , Trasplante de Piel , Animales , Biomarcadores/metabolismo , Western Blotting , Ensayo de Inmunoadsorción Enzimática , Femenino , Rechazo de Injerto/enzimología , Rechazo de Injerto/genética , Rechazo de Injerto/inmunología , Supervivencia de Injerto/genética , Inmunohistoquímica , Ratones , Ratones Endogámicos BALB C , Ratones Transgénicos , Serina Endopeptidasas/genética , Serina Endopeptidasas/metabolismo , Trasplante Homólogo , Resultado del Tratamiento , Regulación hacia ArribaRESUMEN
In this work, we developed a novel light-up nanocluster beacon (NCB) based on shuttling dark silver nanoclusters (NCs) to a bright scaffold through hybridization. The fluorescence enhancement was as high as 70-fold when the two templates were on the opposite sides of the duplexes, enabling sensitive and selective detection of DNA.
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ADN/química , Nanopartículas del Metal , Plata/química , Espectrometría de Fluorescencia , Espectrofotometría UltravioletaRESUMEN
Objective To evaluate the association of cervical cancer and the G/C single nucleotide polymorphism at codon 72 in p53 gene exon -4 in Chinese population.Methods Literatures were searched in CNKI,VIP,CBM, PubMed,EMBase,the Cochrane Library (Issue 1,2015),WanFang Data Database (1980—2015)with computer. Results Thirteen studies involving 1 780 cervical cancer patients and 1 5 17 healthy volunteers were included.According to the situation of the HPV infection in research object,thirteen studies were divided into two subgroups.The results of meta-analyses in the subgroup of non-HPV infection showed that the Chinese women having the genotype G/G presented no increased relative risk compared to that with the genotype C/C(OR=0.980,95%CI:0.558 -1.723).The allele G showed no increased relative risk compared to the allele C (OR=1.070,95%CI:0.789-1.449)The results of meta-analyses in the subgroup of HPV infection showed that the Chinese women having the genotype G/G presented no increased relative risk compared to that with the genotype C/C(OR=0.891,95%CI:0.213 -3.722).The allele G showed no increased relative risk compared to the allele C (OR =0.981,95%CI:0.493 -1.951 ).Conclusion This meta -analysis demonstrates that G/C single nucleotide polymorphism at codon 72 in p53 gene exon-4 were not associated with cervical cancer in Chinese women.
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Guanine proximity based fluorescence enhanced DNA-templated silver nanoclusters (AgNCs) have been reported and applied for bioanalysis. Herein, we studied the G-quadruplex enhanced fluorescence of DNA-AgNCs and gained several significant conclusions, which will be helpful for the design of future probes. Our results demonstrate that a G-quadruplex can also effectively stimulate the fluorescence potential of AgNCs. The major contribution of the G-quadruplex is to provide guanine bases, and its special structure has no measurable impact. The DNA-templated AgNCs were further analysed by native polyacrylamide gel electrophoresis and the guanine proximity enhancement mechanism could be visually verified by this method. Moreover, the fluorescence emission of C3A (CCCA)4 stabilized AgNCs was found to be easily and effectively enhanced by G-quadruplexes, such as T30695, AS1411 and TBA, especially AS1411. Benefiting from the high brightness of AS1411 enhanced DNA-AgNCs and the specific binding affinity of AS1411 for nucleolin, the AS1411 enhanced AgNCs can stain cancer cells for bioimaging.
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ADN/química , Fluorescencia , G-Cuádruplex , Imagen Molecular , Nanoestructuras/química , Plata/química , Células HeLa , HumanosRESUMEN
In this paper, we developed a simple, low-cost and sensitive DNA sequences detection biosensor based on a label-free molecular beacon (MB) whose DNA hairpin structure terminal has a guanine-rich sequence that can enhance fluorescence of silver nanoclusters (Ag NCs). Without hybridization between hairpin probe and target DNA, the Ag NCs presented bright fluorescence for the proximity of guanine-rich sequences (GRSs). After binding with target DNA, the hairpin shape was destroyed which results in a decrease of the Ag NCs fluorescence intensity. With this biosensor, we detected three disease-related genes that were the human immunodeficiency virus (HIV) gene, hepatitis B virus (HBV) gene and human T-lymphotropic virus type I (HTLV-I) gene. The detection limits based on S/N of 3 were 4.4 nM, 6.8 nM and 8.5 nM for HIV gene, HBV gene and HTLV-I gene, respectively. Our sensor was also of high selectivity and could distinguish even one nucleotide mismatched target.
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Técnicas Biosensibles/instrumentación , ADN Viral/análisis , ADN Viral/genética , Nanocompuestos/química , Análisis de Secuencia de ADN/instrumentación , Plata/química , ADN Viral/química , Diseño de Equipo , Análisis de Falla de Equipo , Nanopartículas del Metal/química , Nanopartículas del Metal/ultraestructura , Técnicas de Sonda Molecular/instrumentación , Sondas Moleculares/síntesis química , Nanocompuestos/ultraestructura , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Espectrometría de Fluorescencia/instrumentación , Coloración y EtiquetadoRESUMEN
In this work, a sensitive and selective ratiometric fluorescence sensing platform was built for the detection of tyrosinase (TYR) activity and dopamine (DA) using glutathione (GSH) protected gold nanoclusters (Au NCs) as probes. Upon excitation at 350 nm, Au NCs displayed an intense red emission, which could be effectively quenched by quinones. TYR, a typical polyphenol oxidase, can catalyze the oxidization of DA to o-quinone and therefore quenched the fluorescence of Au NCs. Moreover, the reaction of TYR and DA gave rise to an emission band at 400 nm, which increased in a TYR/DA-concentration-dependent manner. The ratiometric signal variations were utilized for facile, sensitive, and selective detection of TYR activity and DA. A linear range was obtained from 0.006-3.6 unit mL(-1) of TYR activity, while the linear range for detection of DA was 1.0 nM to 1.0 mM. Additionally, it constructed a useful platform for TYR inhibitor screening in biomedical research.