RESUMO
BACKGROUND & AIMS: Although the effect of bacterial infection on cirrhosis has been well-described, the effect of non-hepatotropic virus (NHV) infection is unknown. This study evaluated the genome fragments of circulating microorganisms using metagenomic next-generation sequencing (mNGS) in individuals with acute decompensation (AD) of cirrhosis, focusing on NHVs, and related the findings to clinical outcomes. METHODS: Plasma mNGS was performed in 129 individuals with AD of cirrhosis in the study cohort. Ten healthy volunteers and 20, 39, and 81 individuals with stable cirrhosis, severe sepsis and hematological malignancies, respectively, were enrolled as controls. Validation assays for human cytomegalovirus (CMV) reactivation were performed in a validation cohort (n = 58) and exploratory treatment was instituted. RESULTS: In the study cohort, 188 microorganisms were detected in 74.4% (96/129) of patients, including viruses (58.0%), bacteria (34.1%), fungi (7.4%) and chlamydia (0.5%). A NHV signature was identified in individuals with AD, and CMV was the most frequent NHV, which correlated with the clinical effect of empirical antibiotic treatment, progression to acute-on-chronic liver failure, and 90-day mortality. The NHV signature in individuals with acute-on-chronic liver failure was similar to that in those with sepsis and hematological malignancies. CMV was detected in 24.1% (14/58) of patients in the validation cohort. Of the 14 cases with detectable CMV by mNGS, nine were further validated by real-time PCR or pp65 antigenemia testing. Three patients with CMV reactivation received ganciclovir therapy in an exploratory manner and experienced clinical resolutions. CONCLUSIONS: The results of this study suggest that NHVs may play a pathogenic role in complicating the course of AD. Further validation is needed to define whether this should be incorporated into the routine management of individuals with AD of cirrhosis. IMPACT AND IMPLICATIONS: A non-hepatotropic virus (NHV) signature, which was similar to that in individuals with sepsis and hematological malignancies, was identified in individuals with acute decompensation of cirrhosis. The detected viral signature had clinical correlates, including clinical efficacy of empirical antibiotic treatment, progression to acute-on-chronic liver failure and short-term mortality. Cytomegalovirus reactivation, which is treatable, may adversely affect clinical outcomes in some individuals with decompensated cirrhosis. Routine screening for NHVs, especially cytomegalovirus, may be useful for the management of individuals with acute decompensation of cirrhosis.
Assuntos
Insuficiência Hepática Crônica Agudizada , Infecções por Citomegalovirus , Neoplasias Hematológicas , Sepse , Humanos , Infecções por Citomegalovirus/complicações , Infecções por Citomegalovirus/diagnóstico , Infecções por Citomegalovirus/tratamento farmacológico , Prognóstico , Insuficiência Hepática Crônica Agudizada/etiologia , Insuficiência Hepática Crônica Agudizada/complicações , Citomegalovirus/genética , Cirrose Hepática/diagnóstico , Cirrose Hepática/complicações , Sepse/diagnóstico , Sepse/tratamento farmacológico , Sepse/complicações , Neoplasias Hematológicas/complicaçõesRESUMO
BACKGROUND & AIMS: The Baveno VII consensus recommends that spleen stiffness measurement (SSM) ≤40 kPa is safe for ruling out high-risk varices (HRVs) and avoiding endoscopic screening in patients who do not meet the Baveno VI criteria. This study aimed to validate the performance of the Baveno VII algorithm in individuals with HBV-related cirrhosis. METHODS: Consecutive individuals with HBV-related cirrhosis who underwent liver stiffness measurement (LSM) and SSM - using a 50 Hz shear wave frequency, spleen diameter measurement, and esophagogastroduodenoscopy (EGD) were prospectively enrolled from June 2020. A 100 Hz probe has been adopted for additional SSM assessment since July 2021. RESULTS: From June 2020 to January 2022, 996 patients were screened and 504 were enrolled for analysis. Among the 504 patients in whom SSM was assessed using a 50 Hz probe, the Baveno VII algorithm avoided more EGDs (56.7% vs. 39.1%, p <0.001) than Baveno VI criteria, with a comparable missed HRV rate (3.8% vs. 2.5%). Missed HRV rates were >5% for all other measures: 11.3% for LSM-longitudinal spleen diameter to platelet ratio score, 20.0% for platelet count/longitudinal spleen diameter ratio, and 8.8% for Rete Sicilia Selezione Terapia-hepatitis. SSM@100 Hz was assessed in 232 patients, and the Baveno VII algorithm with SSM@100 Hz spared more EGDs (75.4% vs. 59.5%, p <0.001) than that with SSM@50 Hz, both with a missed HRV rate of 3.0% (1/33). CONCLUSIONS: We validated the Baveno VII algorithm, demonstrating the excellent performance of SSM@50 Hz and SSM@100 Hz in ruling out HRV in individuals with HBV-related cirrhosis. Furthermore, the Baveno VII algorithm with SSM@100 Hz could safely rule out more EGDs than that with SSM@50 Hz. CLINICAL TRIAL NUMBER: NCT04890730. IMPACT AND IMPLICATIONS: The Baveno VII guideline proposed that for patients who do not meet the Baveno VI criteria, SSM ≤40 kPa could avoid further unnecessary endoscopic screening. The current study validated the Baveno VII algorithm using 50 Hz and 100 Hz probes, which both exhibited excellent performance in ruling out HRVs in individuals with HBV-related cirrhosis. Compared with the Baveno VII algorithm with SSM@50 Hz, SSM@100 Hz had a better capability to safely rule out unnecessary EGDs. Baveno VII algorithm will be a practical tool to triage individuals with cirrhosis in future clinical practice.
Assuntos
Técnicas de Imagem por Elasticidade , Varizes Esofágicas e Gástricas , Varizes , Humanos , Vírus da Hepatite B , Cirrose Hepática/diagnóstico , AlgoritmosRESUMO
The aim of this study was to determine the effect of dexamethasone (DEX) on renal ischemia/reperfusion injury (IRI). C57BL/6 mice were randomly divided into Sham group, IRI group and DEX group. The mice in IRI and DEX groups subjected to renal ischemia for 60 min, were treated with saline or DEX (4 mg/kg, i.p.) 60 min prior to I/R. After 24 h of reperfusion, the renal function, renal pathological changes, activation of extracellular signal-regulated kinase (ERK) and glucocorticoid receptor (GR), and the levels of iNOS and eNOS were detected. The results showed DEX significantly decreased the damage to renal function and pathological changes after renal IRI. Pre-treatment with DEX reduced ERK activation and down-regulated the level of iNOS, whereas up-regulated the level of eNOS after renal IRI. DEX could further promote the activation of GR. These findings indicated GR activation confers preconditioning-like protection against acute IRI partially by up-regulating the ratio of eNOS/iNOS.
Assuntos
Dexametasona/farmacologia , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Glucocorticoides/farmacologia , Óxido Nítrico Sintase Tipo III/biossíntese , Óxido Nítrico Sintase Tipo II/biossíntese , Receptores de Glucocorticoides/agonistas , Traumatismo por Reperfusão/enzimologia , Regulação para Cima/efeitos dos fármacos , Animais , Masculino , Camundongos , Traumatismo por Reperfusão/patologiaRESUMO
BACKGROUND: There is growing recognition of natural history, complications, and outcomes of patients who develop non-acetaminophen (APAP) drug-induced acute liver failure (ALF). To clarify high-risk factors and develop a nomogram model to predict transplant-free survival (TFS) in patients with non-APAP drug-induced ALF. METHODS: Patients with non-APAP drug-induced ALF from 5 participating centers were retrospectively analyzed. The primary endpoint was 21-day TFS. Total sample size was 482 patients. RESULTS: Regarding causative agents, the most common implicated drugs were herbal and dietary supplements (HDS) (57.0%). The hepatocellular type (R ≥ 5) was the main liver injury pattern (69.0%). International normalized ratio, hepatic encephalopathy grades, the use of vasopressor, N-acetylcysteine, or artificial liver support system were associated with TFS and incorporated to construct a nomogram model (drug-induced acute liver failure-5, DIALF-5). The AUROC of DIALF-5 for 7-day, 21-day, 60-day, and 90-day TFS in the internal cohort were 0.886, 0.915, 0.920, and 0.912, respectively. Moreover, the AUROC of DIALF-5 for 21-day TFS had the highest AUROC, which was significantly higher than 0.725 of MELD and 0.519 of KCC (p < 0.05), numerically higher than 0.905 of ALFSG-PI but without statistical difference (p > 0.05). These results were successfully validated in the external cohort (147 patients). CONCLUSIONS: Based on easily identifiable clinical data, the novel DIALF-5 model was developed to predict transplant-free survival in non-APAP drug-induced ALF, which was superior to KCC, MELD and had a similar prediction performance to ALFSG-PI but is more convenient, which can directly calculate TFS at multiple time points.
Assuntos
Falência Hepática Aguda , Humanos , Estudos Retrospectivos , Prognóstico , Falência Hepática Aguda/etiologia , Nomogramas , Fatores de RiscoRESUMO
BACKGROUND: Esophagogastroduodenoscopy (EGD) is required to screen for high-risk varices (HRV) in patients with hepatocellular carcinoma (HCC), especially since overall survival rates have dramatically improved with new systemic therapies. AIM: To assess the Baveno VI and Baveno VII algorithms' ability to rule out HRV in hepatitis B virus (HBV)-related HCC METHODS: We prospectively enrolled consecutive patients with HBV related, compensated cirrhosis and newly diagnosed HCC who underwent liver stiffness measurement, spleen stiffness measurement (SSM) using a 100-Hz shear wave frequency, and EGD. RESULTS: From September 2021 to August 2023, we enrolled 219 patients with HCC, with 107 (48.9%) Barcelona Clinic Liver Cancer (BCLC) A, 28 (12.8%) BCLC B and 84 (38.3%) BCLC C, respectively. HRV prevalence was 28.8% (63/219). Baveno VI criteria safely (HRV missing rate, 3.2%) avoided 27.4% unnecessary EGDs, while the Baveno VII algorithm avoided 49.3% with HRV missing rate at 7.9% (5/63). The SSM ≤40 kPa avoided 47.5% of EGDs safely (HRV missing rate, 4.8%), significantly better than the Baveno VI criteria (p < 0.001) and comparable to the Baveno VII algorithm (p = 0.390). The SSM ≤40 kPa safely avoided EGDs in patient subgroups within Milan criteria, with portal vein tumour thrombosis or BCLC B/C or candidates for systemic therapy. CONCLUSIONS: We validated that the SSM ≤40 kPa using a 100-Hz probe could safely eliminate more unnecessary EGDs than the Baveno VI criteria in patients with HBV-related HCC. However, the efficacy of the Baveno VII algorithm in patients with HCC requires further investigation.
Assuntos
Carcinoma Hepatocelular , Técnicas de Imagem por Elasticidade , Varizes Esofágicas e Gástricas , Neoplasias Hepáticas , Varizes , Humanos , Carcinoma Hepatocelular/diagnóstico , Carcinoma Hepatocelular/etiologia , Vírus da Hepatite B , Varizes Esofágicas e Gástricas/diagnóstico , Varizes Esofágicas e Gástricas/etiologia , Baço/diagnóstico por imagem , Neoplasias Hepáticas/diagnóstico , Cirrose Hepática/complicações , Cirrose Hepática/diagnósticoRESUMO
AIMS: To prospectively evaluate the performance of spleen stiffness measurement (SSM) and liver stiffness measurement (LSM) via acoustic radiation force impulse (ARFI) imaging combined with platelet counts (PLT) in ruling out HRV in HBV-related cirrhotic patients with viral suppression. METHODS: Patients with cirrhosis enrolled between June 2020-March 2022 were divided into a derivation cohort and validation cohort. LSM and SSM ARFI-based, and esophagogastroduodenoscopy (EGD) were performed at enrollment. RESULTS: In the derivation cohort, overall, 236 HBV-related cirrhotic patients with maintained viral suppression were enrolled, and the prevalence of HRV was 19.5% (46/236). With the aim of identifying HRV, the most accurate LSM and SSM cut-offs were chosen of 1.46 m/s and 2.28 m/s, respectively. The combined model (LSM<1.46 m/s and PLT>150 × 109/L strategy combined with SSM ≤ 2.28 m/s) can spare 38.6% of EGDs and 4.3% of HRV cases were misclassified. In the validation cohort, we analysed 323 HBV-related cirrhotic patients with maintained viral suppression and validated the combined model can spare 33.4% (108/323) of EGD, and the HRV missed rate was 3.4%. CONCLUSIONS: A non-invasive prediction model combining LSM<1.46 m/s and PLT>150 × 109/L strategy with SSM ≤ 2.28 m/s exhibited excellent performance in ruling out HRV and avoided a significantly large number (38.6% vs 33.4%) of unnecessary EGDs in HBV-related cirrhotic patients with viral suppression.
Assuntos
Técnicas de Imagem por Elasticidade , Varizes Esofágicas e Gástricas , Varizes , Humanos , Vírus da Hepatite B , Varizes Esofágicas e Gástricas/etiologia , Varizes Esofágicas e Gástricas/patologia , Cirrose Hepática/complicações , Cirrose Hepática/diagnóstico por imagem , Cirrose Hepática/patologia , Técnicas de Imagem por Elasticidade/métodos , Acústica , Fígado/diagnóstico por imagem , Fígado/patologiaRESUMO
Colorectal carcinoma (CRC) is often lethal when invasion and/or metastasis occur. NAD(+)-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH), an enzyme involved in prostaglandin (including PGE(2)) bio-inactivation, is down-expressed in several epithelial malignancies including CRC. Although its role in the suppression of colon tumorigenesis has been well learned, little is known about the role of 15-PGDH in the process of tumor metastasis. Here, we tested the hypothesis that 15-PGDH over-expression in CRC cells results in decreased cell motility and invasion. In this study, 15-PGDH was re-expressed in SW480 cells by the use of gene transient transfection with eukaryotic expression vector pcDNA3.1-PGDH. We confirmed the over-expression of 15-PGDH protein by Western blot and enzymatic activity assay. The cell motility was tested by counting the number of cells crossing an 8-micron pore size PET membrane and by measuring cells migration distance through wound healing assay. Furthermore, cell invasive activity was evaluated by counting the number of cells invading through a Matrigel-coated membrane simulating basement membrane. The effects of 15-PGDH on the adhesion were investigated by MTT assay. Ectopic expression of 15-PGDH in SW480 cancer cells significantly inhibited the cell migratory and invasive capacity in vitro by approximately 1.9- and 8.4-fold, respectively. To test the hypothesis that 15-PGDH affects proteases and inactivates extracellular matrix (ECM), Western blot and gelatin zymography were performed by using serum-free conditioned medium. The results showed that re-expression of 15-PGDH suppresed matrix metalloproteinase-2 (MMP2) synthesis and secretion. In addition, the analysis of the MMP2 activity indicated that re-expression of 15-PGDH could inhibit activation of MMP2. Furthermore, we found that 15-PGDH inhibited cell adhesion to ECM and reduced CD44 expression in SW480 cell. Taken together, these results suggest that induced 15-PGDH expression may contribute to the inhibition of the invasive and metastatic capacity of colon cancer cells in vitro.
Assuntos
Adenocarcinoma/enzimologia , Adenocarcinoma/patologia , Neoplasias Colorretais/enzimologia , Neoplasias Colorretais/patologia , Hidroxiprostaglandina Desidrogenases/biossíntese , Adesão Celular/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Humanos , Receptores de Hialuronatos/biossíntese , Hidroxiprostaglandina Desidrogenases/genética , Metaloproteinase 2 da Matriz/biossíntese , Invasividade Neoplásica , TransfecçãoRESUMO
Elevated expression of CXCL9 has been shown to involve in the infiltration of inflammatory cells and liver damage after Hepatitis B virus (HBV) infection. However, whether and by what underlying mechanism does CXCL9 play a role in HBV infection associated hepatocellular carcinoma (HCC) invasion ability remain unclear. In this study, human HCC as well as adjacent noncancerous tissues, together with three kinds of liver cancer cell lines were investigated to clarify the possible involvement of CXCL9 in the regulation of HCC invasion and metastasis. Invasion ability of liver cancer cells were evaluated by transwell assays and it is enhanced after co-cultured with recombined human CXCL9 (rhCXCL9). As a trigger of Rac GTPase signaling after G protein-coupled receptors (GPCR) activated by CXCL9, Phosphatidylinositol-3, 4, 5-trisphosphate RAC Exchanger 2 (PREX2) mRNA expression of the liver cancer cell lines was elevated after co-cultured with rhCXCL9. Moreover, the mRNA level of PREX2 in HCC tissues was significantly higher than those in adjacent noncancerous tissues. Besides, the mRNA levels of PREX2 were positively correlated with the poor differentiation, portal vein invasion, metastasis and qualitative HbsAg results in 45 pairs of HCC specimens. Similarly, PREX2 mRNA was higher in three liver cancer cell lines when compared with the normal liver cell line whereas knocked down of PREX2 by small interference RNA (PREX2-siRNA) reduced the invasion ability of liver cancer cells in transwell assays. Overall, our results suggested CXCL9 was involved in the invasion ability of HCC possibly through up-regulation of its potential effector PREX2.
Assuntos
Carcinoma Hepatocelular/metabolismo , Quimiocina CXCL9/fisiologia , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Neoplasias Hepáticas/metabolismo , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Movimento Celular , Técnicas de Cocultura , Feminino , Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Fatores de Troca do Nucleotídeo Guanina/genética , Humanos , Neoplasias Hepáticas/patologia , Masculino , Pessoa de Meia-Idade , Regulação para CimaRESUMO
BACKGROUND: Diarrhea is a common clinical feature of ulcerative colitis resulting from unbalanced intestinal fluid and salt absorption and secretion. The Cl(-)/HCO3(-) exchanger SLC26A3 is strongly expressed in the mid-distal colon and plays an essential role in colonic Cl(-) absorption and HCO3(-) secretion. Slc26a3 expression is up-regulated by lysophosphatidic acid (LPA) in vitro. Our study was designed to investigate the effects of LPA on SLC26A3 expression and the diarrheal phenotype in a mouse colitis model. METHODS: Colitis was induced in C57BL/6 mice by adding 4% of dextran sodium sulfate (DSS) to the drinking water. The mice were assigned to LPA treatment DSS group, phosphate-buffered saline (PBS) treatment DSS group, DSS only group and untreated mice with a completely randomized design. Diarrhea severity was evaluated by measuring mice weight, disease activity index (DAI), stool water content and macroscopic evaluation of colonic damage. The effect of LPA treatment on Slc26a3 mRNA level and protein expression in the different groups of mice was investigated by quantitative PCR and Western blotting. RESULTS: All mice treated with DSS lost weight, but the onset and severity of weight loss was attenuated in the LPA treatment DSS group. The increases in stool water content and the macroscopic inflammation score in LPA treatment DSS group were significantly lower compared to DSS control group or PBS treatment DSS group ((18.89±8.67)% vs. (28.97±6.95)% or (29.48±6.71)%, P = 0.049, P = 0.041, respectively and 2.67±0.81 vs. 4.5±0.83 or 4.5±0.54, P = 0.020, P = 0.006, respectively), as well as the increase in DAI (P = 0.004, P = 0.008, respectively). LPA enema resulted in higher Slc26a3 mRNA and protein expression levels compared to PBS-treated and untreated DSS colitis mice. CONCLUSION: LPA increases Slc26a3 expression in the inflamed intestine and reduces diarrhea severity in DSS-induced colitis, suggesting LPA might be a therapeutic strategy in the treatment of colitis associated diarrhea.
Assuntos
Antiporters/metabolismo , Colite/tratamento farmacológico , Sulfato de Dextrana/farmacologia , Dextranos/farmacologia , Diarreia/tratamento farmacológico , Mucosa Intestinal/metabolismo , Intestinos/efeitos dos fármacos , Lisofosfolipídeos/uso terapêutico , Animais , Antiporters/genética , Colite/induzido quimicamente , Colo/imunologia , Colo/metabolismo , Diarreia/metabolismo , Feminino , Immunoblotting , Camundongos , Camundongos Endogâmicos C57BL , Transportadores de SulfatoRESUMO
Dexamethasone (DEX), a ligand for glucocorticoid receptor (GR), has long been used in the clinical practice due to its anti-inflammatory and immunosuppressive properties. Given that ischemia/reperfusion (IR)-induced renal injury is featured by the excessive immune response; the current study is therefore designed to address the impact of dexamethasone on IR-induced renal injury, a common disorder in the clinical settings. Precondition of mice with 4 mg/kg of dexamethasone significantly attenuated IR-induced injury as manifested by the improved renal function along with ameliorated pathological changes and suppressed inflammatory infiltration. Mechanistic studies revealed that dexamethasone promotes GR activation, and by which it attenuates the signals for PI3K/AKT activation. Attenuated PI3K/AKT signaling thus suppresses inflammatory response which then protects kidneys from IR-induced injury. All together, our data support that dexamethasone could be a good alternative therapy for prevention and treatment of IR-induced renal injury in the clinical practice.
Assuntos
Injúria Renal Aguda/prevenção & controle , Dexametasona/farmacologia , Glucocorticoides/farmacologia , Rim/efeitos dos fármacos , Fosfatidilinositol 3-Quinase/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Traumatismo por Reperfusão/prevenção & controle , Transdução de Sinais/efeitos dos fármacos , Injúria Renal Aguda/enzimologia , Injúria Renal Aguda/genética , Injúria Renal Aguda/patologia , Injúria Renal Aguda/fisiopatologia , Animais , Citocinas/genética , Citocinas/metabolismo , Citoproteção , Modelos Animais de Doenças , Regulação da Expressão Gênica , Mediadores da Inflamação/metabolismo , Rim/irrigação sanguínea , Rim/enzimologia , Rim/patologia , Rim/fisiopatologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , RNA Mensageiro/metabolismo , Receptores de Glucocorticoides/agonistas , Receptores de Glucocorticoides/metabolismo , Traumatismo por Reperfusão/enzimologia , Traumatismo por Reperfusão/genética , Traumatismo por Reperfusão/patologia , Traumatismo por Reperfusão/fisiopatologiaRESUMO
Selective detection of cysteine in serum samples was achieved on a graphene nanoribbon (GNR) and Nafion nanocomposite modified electrode with high precision. The superior conductivity and abundant amount of active chemical oxygen groups on the edge of GNR led to extremely highly electrocatalytic activity of GNR towards the electrochemical oxidation of cysteine at +0.025 V. The electrocatalytic behavior was further used for sensitive detection of cysteine by differential pulse voltammetry. Under optimized conditions, the calibration curve was linear in the range from 25 nM to 500 µM. The electrochemical sensor showed strong antifouling ability, good stability and selectivity. It could effectively exclude the interferences from other kinds of biothiols and the biological relevant species, thus had great perspective for in vivo analysis of biological samples.
Assuntos
Técnicas Biossensoriais/métodos , Cisteína/sangue , Técnicas Eletroquímicas/métodos , Grafite/química , Nanotubos de Carbono/química , Humanos , Oxirredução , Sensibilidade e EspecificidadeRESUMO
A sensitive amperometric acetylcholinesterase (AChE) biosensor was fabricated based on mesocellular silica foam (MSF), which functioned as both an enzyme immobilization matrix and a solid phase extraction (SPE) material for the preconcentration of target molecules. The hydrophilic interface, the good mechanical/chemical stability, and the suitable pore dimension of MSF provided the entrapped AChE a good environment to well maintain its bioactivity at basic condition. The AChE immobilized in MSF showed improved catalytic ability for the hydrolysis of acetylthiocholine, as evidenced by the increasing of the oxidation current of thiocholine, the enzymatic catalytic hydrolysis production of acetylthiocholine. In addition, the MSF with large surface area showed a modest adsorption capacity for monocrotophos, a model organophosphate used in this study, via the hydrogen bond or physical adsorption interaction. The combination of the SPE and the good enzyme immobilization ability in MSF significantly promoted the sensitivity of the biosensor, and the limit of detection has lowered to 0.05 ng/mL. The biosensor exhibited accuracy, good reproducibility, and acceptable stability when used for garlic samples analysis. The strategy may provide a new method to fabricate highly sensitive biosensors for the detection of ultra-trace organophosphorous pesticide infield.
Assuntos
Técnicas Biossensoriais/métodos , Compostos Organofosforados/análise , Praguicidas/análise , Dióxido de Silício , Acetilcolinesterase/metabolismo , Acetiltiocolina/metabolismo , Técnicas Biossensoriais/estatística & dados numéricos , Enzimas Imobilizadas/metabolismo , Contaminação de Alimentos/análise , Alho/química , Monocrotofós/análiseRESUMO
Electrochemical reduced ß-cyclodextrin dispersed graphene (ß-CD-graphene) was developed as a sorbent for the preconcentration and electrochemical sensing of methyl parathion (MP), a representative nitroaromatic organophosphate pesticide with good redox activity. Benefited from the ultra-large surface area, large delocalized π-electron system and the superconductivity of ß-CD-graphene, large amount of MP could be extracted on ß-CD-graphene modified electrode via strong π-π interaction and exhibited fast accumulation and electron transfer rate. Combined with differential pulse voltammetric analysis, the sensor shows ultra-high sensitivity, good selectivity and fast response. The limit of detection of 0.05 ppb is more than 10 times lower than those obtained from other sorbent based sensors. The method may open up a new possibility for the widespread use of electrochemical sensors for monitoring of ultra-trace OPs.
Assuntos
Técnicas Eletroquímicas/métodos , Grafite/química , Metil Paration/análise , Praguicidas/análise , Transporte de Elétrons , Metil Paration/isolamento & purificação , Oxirredução , Praguicidas/isolamento & purificação , beta-Ciclodextrinas/químicaRESUMO
An ultrasensitive amperometric acetylcholinesterase (AChE) biosensor was fabricated by controlled immobilization of AChE on gold nanoparticles/poly(dimethyldiallylammonium chloride) protected Prussian blue (Au-PDDA-PB) nanocomposite modified electrode surface for the detection of organophorous pesticide. The Au-PDDA-PB membrane served as an excellent matrix for the immobilization of enzyme, which not only enhanced electron transfer but also possessed a relatively large surface area. In addition, the surface hydrophilicity of the Au-PDDA-PB nanocomposite was finely controlled in the static water contact angle range of 25.6-78.1° by adjusting the ratio of gold nanoparticles to PDDA-PB. On an optimized hydrophobic surface, the AChE adopts an orientation with both good activity and stability, which has been proven by electrochemical methods. Benefit from the advantages of the Au-PDDA-PB nanocomposite and the good activity and stability of AChE, the biosensor shows significantly improved sensitivity to monocrotophos, a typical highly toxic organophorous pesticide, with wide linear range (1.0-1000 pg/mL and 1.0-10 ng/mL) and an ultra-low detection limit of 0.8 pg/mL. The biosensor exhibits accuracy, good reproducibility and stability. This strategy may therefore provide useful information for the controlled immobilization of protein and the design of highly sensitive biosensors.