RESUMO
OBJECTIVE: The diagnosis of intracranial atherosclerosis (ICAS) associated with large vessel occlusion (LVO) before endovascular treatment (EVT) remains a clinical challenge. This study was aimed at developing a predictive model for ICAS-LVO in the anterior circulation preceding EVT. METHODS: Patients from two national stroke centers who had undergone EVT for acute ischemic stroke in the anterior circulation were evaluated. Those from one center served as the derivation cohort, whereas patients from another center functioned as the external validation cohort. ICAS-LVO was characterized as stenosis exceeding 70% or stenosis surpassing 50% accompanied by distal blood flow disruption or recurrent occlusion evidence during the intervention. A random forest algorithm helped to identify key predictors within the derivation cohort. Utilizing these predictors, the authors formulated a logistic regression model from the derivation cohort data, and the model was then internally validated through a bootstrapping method. Subsequently, a predictive score based on this model was constructed and evaluated in both cohorts. RESULTS: Among all the patients, 470 from the derivation cohort and 147 from the external validation cohort met the inclusion criteria. After random forest regression, the key predictors of ICAS-LVO included the absence of atrial fibrillation, the presence of truncal-type occlusion, the absence of a hyperdense artery sign, and a lower baseline examination National Institutes of Health Stroke Scale (NIHSS) score (ATHE Scale). Incorporating these variables into the logistic regression model yielded an area under the curve (AUC) of 0.920 (95% CI 0.894-0.947) for ICAS-LVO prediction. After bootstrapping validation, the model produced a mean AUC of 0.915. Subsequently, the ATHE score, derived from these predictors, registered an AUC of 0.916 (95% CI 0.887-0.939, p < 0.001) in the derivation cohort and 0.890 (95% CI 0.828-0.936, p < 0.001) in the external validation cohort. CONCLUSIONS: The ATHE Scale, incorporating atrial fibrillation, truncal-type occlusion, hyperdense artery sign, and baseline examination NIHSS score, is an accurate, objective tool for predicting ICAS-LVO prior to EVT.
Assuntos
Procedimentos Endovasculares , Arteriosclerose Intracraniana , Humanos , Arteriosclerose Intracraniana/diagnóstico por imagem , Arteriosclerose Intracraniana/complicações , Feminino , Masculino , Procedimentos Endovasculares/métodos , Idoso , Pessoa de Meia-Idade , AVC Isquêmico/diagnóstico por imagem , AVC Isquêmico/cirurgia , AVC Isquêmico/etiologia , Estudos de Coortes , Estudos Retrospectivos , Valor Preditivo dos Testes , Idoso de 80 Anos ou maisRESUMO
BACKGROUND: Malignant brain edema (MBE) is a life-threatening complication that can occur after mechanical thrombectomy (MT) for acute ischemic stroke. The hypoperfusion intensity ratio (HIR) reflects the tissue-level perfusion status within the ischemic territory. This study investigated the association between HIR and MBE occurrence after MT in patients with anterior circulation large artery occlusion. METHODS: We conducted a retrospective cohort study of patients who received MT at a comprehensive stroke center from February 2020 to June 2022. Using computed tomography perfusion, the HIR was derived from the ratio of tissue volume with a time to maximum (Tmax) > 10 s to that with a Tmax > 6 s. We dichotomized patients based on the occurrence of MBE following MT. The primary outcome, assessed using a multivariable logistic regression model, was the MBE occurrence post MT. The secondary outcome focused on favorable outcomes, defined as achieving a modified Rankin Scale score of 0-2 at 90 days. RESULTS: Of the 603 included patients, 90 (14.9%) developed MBE after MT. The median HIR exhibited a significantly higher value in the MBE group compared with the non-MBE group (0.5 vs. 0.3; P < 0.001). Multivariable logistic regression analysis indicated that a higher HIR (adjusted odds ratio [aOR] 8.98; 95% confidence interval [CI] 2.85-28.25; P < 0.001), baseline large infarction (Alberta Stroke Program Early Computed Tomography Score < 6; aOR 1.77; 95% CI 1.04-3.01; P = 0.035), internal carotid artery occlusion (aOR 1.80; 95% CI 1.07-3.01; P = 0.028), and unsuccessful recanalization (aOR 8.45; 95% CI 4.75-15.03; P < 0.001) were independently associated with MBE post MT. Among those with successful recanalization, a higher HIR (P = 0.017) and baseline large infarction (P = 0.032) remained as predictors of MBE occurrence. Furthermore, a higher HIR (P = 0.001) and the occurrence of MBE (P < 0.001) both correlated with reduced odds of achieving favorable outcomes. CONCLUSIONS: The presence of a higher HIR on pretreatment perfusion imaging serves as a robust predictor for MBE occurrence after MT, irrespective of successful recanalization.
Assuntos
Edema Encefálico , Isquemia Encefálica , AVC Isquêmico , Acidente Vascular Cerebral , Humanos , Edema Encefálico/diagnóstico por imagem , Edema Encefálico/etiologia , AVC Isquêmico/cirurgia , Estudos Retrospectivos , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/cirurgia , Isquemia Encefálica/cirurgia , Isquemia Encefálica/etiologia , Trombectomia/efeitos adversos , Trombectomia/métodos , Reperfusão , Infarto/etiologiaRESUMO
It has been shown in recent studies that the crustacean female sex hormone (CFSH) plays a crucial role in the development of secondary sexual characteristics in Decapoda crustaceans. However, research on the function of CFSH in the eyestalk-AG-testicular endocrine axis has been inadequate. We cloned and identified a homolog of CFSH, PtCFSH, in this study. RT-PCR showed that PtCFSH was mainly expressed in the eyestalk. A long-term injection of dsPtCFSH and recombinant PtCFSH (rPtCFSH) in vivo showed opposite effects on spermatogenesis-related gene expression and histological features in the testis of P. trituberculatus, and was accompanied by changes in AG morphological characteristics and PtIAG expression. In addition, the phosphorylated-MAPK levels and the expression of several IIS pathway genes in the testis was changed accordingly in two treatments, suggesting that PtCFSH may regulate the testicular development via IAG. The hypothesis was further validated by a mixed injection of both dsPtCFSH and dsPtIAG in vivo. The following in vitro studies confirmed the negatively effects of PtCFSH on AG, and revealed that the PtCFSH can also act directly on the testis. Treatment with rPtCFSH reduced the cAMP and cGMP levels as well as the nitric oxide synthetase activity. These findings provide vital clues to the mechanisms of CFSH action in both the eyestalk-AG-testis endocrinal axis and its direct effects on the testis.
RESUMO
AbstractThe insulin-like androgenic gland hormone is a crucial sexual regulator that is involved in the masculine sexual differentiation of crustaceans. As an insulin-like peptide, the insulin-like androgenic gland hormone has been proposed to act through the insulin receptor-mediated pathway. The present study cloned and characterized two insulin receptors (PtIR1 and PtIR2) from the swimming crab Portunus trituberculatus hallmarked with a conserved intracellular tyrosine kinase catalytic domain and several other typical insulin receptor domains in their deduced amino acid sequences. Both insulin receptors were predominately expressed in the testis and the insulin-like androgenic gland hormone-producing organ androgenic gland. Their testicular expression during the annual cycle suggested that they may play critical roles in spermatogenesis. By using the protein colocalization analysis in HEK293 cells, interactions of PtIAG with the two PtIRs were further confirmed. In addition, the insulin receptor antagonist was found to attenuate the stimulatory effects of androgenic gland homogenate on the phosphorylated MAPK levels in testis explants, suggesting that the insulin receptor-dependent MAPK pathway may be essential for insulin-like androgenic gland hormone functions.
Assuntos
Braquiúros , Receptor de Insulina , Animais , Braquiúros/genética , Braquiúros/metabolismo , Receptor de Insulina/metabolismo , Receptor de Insulina/genética , Masculino , Humanos , Células HEK293 , Testículo/metabolismo , Sequência de AminoácidosRESUMO
CYP15, which encodes a microsomal cytochrome P450 enzyme, could be involved in juvenile hormone biosynthesis in insects. In this study, a full-length cDNA of CYP15 was cloned from the swimming crab Portunus trituberculatus. This PtCYP15 amino acid sequence contains six conserved domains, which is a typical feature of the cytochrome P450 family. Phylogenetic tree analysis results showed that PtCYP15 clusters in a single branch of crustacean species, suggesting that CYP15 may be more widely present in crustaceans. The PtCYP15 mRNA has a broad pattern of tissue expression in P. trituberculatus, including high levels of expression in the hepatopancreas of both sexes and in the ovary of female crabs. During ovarian development stages, PtCYP15 mRNA is highly expressed in stages I and II and less so in stages III and IV in the hepatopancreas and the ovary of the female crabs. These expression profiles are opposite those of methyl farnesoate in hemolymph, suggesting that PtCYP15 might be involved in methyl farnesoate metabolism. In vitro studies show that only methyl farnesoate upregulated vitellogenin expression in the hepatopancreas, suggesting that methyl farnesoate might be the equivalent of juvenile hormone III in crustaceans. Methyl farnesoate treatment increased levels of PtCYP15 in explants of the hepatopancreas and ovary, while juvenile hormone III treatment reduced levels of PtCYP15 mRNA in ovary explants, suggesting that PtCYP15 might be involved in degrading methyl farnesoate. Furthermore, PtCYP15 mRNA expression levels were inhibited by adding juvenile hormone III to ovary explants. These findings provide foundational information for future research on methyl farnesoate metabolism in crustaceans.
Assuntos
Braquiúros , Animais , Braquiúros/genética , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Ácidos Graxos Insaturados , Feminino , Oxirredutases , Filogenia , RNA Mensageiro/genética , NataçãoRESUMO
The insulin-like growth factor/insulin-like polypeptide (IGF/ILP) signaling is vital for growth, physiological metabolism, development, and reproduction. Insulin-like growth factor-binding protein (IGFBP) is involved in the insulin signaling pathway in both vertebrates and invertebrates and is critical for various physiology functions. Herein, we cloned and characterized the full-length cDNA of IGFBP-rp in the swimming crab, Portunus trituberculatus (PtIGFBP-rp). The deduced amino acid sequence of PtIGFBP-rp was found to contain three key domains (insulin-like binding (IB) domain, the kazale-type serine protease inhibitor (KAZAL) domain, and the immunoglobulin-like C2 (IGc2) domain). Results showed that PtIGFBP-rp shared the same expression pattern as P. trituberculatus insulin androgenic gland hormone (PtIAG) transcripts during the embryonic larval, juvenile crab stage and the androgenic gland (AG) developmental cycle. Moreover, PtIGFBP-rp transcripts were also present in high abundance in hepatopancreas, muscle, and androgenic glands. The regulatory relationship between PtIGFBP-rp and PtIAG was investigated by RNA interference and co-localization assays, which showed a co-localization relationship and feedback regulation between them. Bilateral eye stalk ablation (ESA) increased the expression of PtIGFBP-rp in the AG at 7 d after surgery. These results demonstrate the involvement of PtIGFBP-rp in the signaling regulatory network of IAG in P. trituberculatus.
Assuntos
Braquiúros , Somatomedinas , Androgênios/metabolismo , Animais , Braquiúros/genética , Braquiúros/metabolismo , Insulina/metabolismo , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/genética , Peptídeos e Proteínas de Sinalização Intercelular/genética , Filogenia , Somatomedinas/genética , Somatomedinas/metabolismo , NataçãoRESUMO
Confined nanosized spaces at the interface between a metal and a seemingly inert material, such as a silicate, have recently been shown to influence the chemistry at the metal surface. In prior work, we observed that a bilayer (BL) silica on Ru(0001) can change the reaction pathway of the water formation reaction (WFR) near room temperature when compared to the bare metal. In this work, we looked at the effect of doping the silicate with Al, resulting in a stoichiometry of Al0.25Si0.75O2. We investigated the kinetics of WFR at elevated H2 pressures and various temperatures under interfacial confinement using ambient pressure X-ray photoelectron spectroscopy. The apparent activation energy was lower than that on bare Ru(0001) but higher than that on the BL-silica/Ru(0001). The apparent reaction order with respect to H2 was also determined. The increased residence time of water at the surface, resulting from the presence of the BL-aluminosilicate (and its subsequent electrostatic stabilization), favors the so-called disproportionation reaction pathway (*H2O + *O â 2 *OH), but with a higher energy barrier than for pure BL-silica.
RESUMO
The growth of the silica (SiO2) bilayer (BL) films on transition metal (TM) surfaces creates a new class of two-dimensional (2D) crystalline, self-contained materials that interact weakly with the TM substrate. The BL-silica/TM heterojunction has shown unique physical and chemical properties that can lead to new chemical reaction mechanisms under the sub-nm confinement and broad potential applications ranging from surface protection, nano transistors, molecular sieves to nuclear waste removal. Novel applications of BL-silica can be further explored as a constituent of van der Waals assembly of 2D materials. Key to these applications is an unmet technical challenge to exfoliate and transfer BL-silica films in a large area from one substrate to another without material damage. In this study, we propose a new exfoliation mechanism based on gas molecule intercalation from density functional theory studies of the BL-silica/TM heterojunction. We found that the intercalation of O atoms and CO molecules at the BL-silica/TM interface weakens the BL-silica-TM hybridization, which results in an exponential decrease of the exfoliation energy against the interface distance as the coverage of interfacial species increases. This new intercalation mechanism opens up the opportunity for non-damaging exfoliation and transfer of large area silica bilayers.
RESUMO
OBJECTIVE: Based on the unclear safety and effectiveness of direct balloon angioplasty as a first-line treatment for patients with acute ischemic stroke caused by large artery atherosclerosis (LAA), our paper would center on investigating the safety and effectiveness of this novel strategy. PATIENTS AND METHODS: A consecutive series of acute ischemic stroke patients due to intracranial atherosclerosis and short thrombus who underwent thorough direct balloon angioplasty from October 2019 to March 2021 were enrolled. The primary end point included arterial recanalization (modified Thrombolysis in Cerebral Infarction [mTICI]: 2b-3), and 90-day functional independence (modified Rankin Scale[mRS]: 0-2). The secondary end point was symptomatic intracerebral hemorrhage (sICH) and perioperative restenosis and re-occlusion of offending vessel. RESULTS: 68 patients were included. Mean time from onset to groin puncture was 342.5 min and 50 min for groin puncture to successful recanalization. 61 (89.7%) patients achieved successful recanalization and 41 (60.3%) acquired functional independence. 11 (16.0%) patients experienced ICH and only 3 (4.4%) for sICH. 8 (11.8%) patients developed symptomatic restenosis or re-occlusion within seven days after the operation. In addition, 16 (23.5%) patients received rescue stenting and 3 (18.8%) of this subgroup appeared immediate intra-stent thrombosis. CONCLUSION: Direct balloon angioplasty may be a safe and effective method for the treatment of stroke caused by intracranial large arteriosclerosis occlusion.
Assuntos
Angioplastia com Balão/efeitos adversos , Arteriosclerose Intracraniana/cirurgia , AVC Isquêmico/cirurgia , Complicações Pós-Operatórias/epidemiologia , Trombectomia/efeitos adversos , Idoso , Feminino , Humanos , Arteriosclerose Intracraniana/complicações , Arteriosclerose Intracraniana/diagnóstico por imagem , AVC Isquêmico/etiologia , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Stents , Resultado do TratamentoRESUMO
Neuropeptides and their G protein-coupled receptors (GPCRs) regulate multiple physiological processes. Currently, little is known about the identity of native neuropeptides and their receptors in Portunus trituberculatus. This study employed RNA-sequencing and reverse transcription-polymerase chain reaction (RT-PCR) techniques to identify neuropeptides and their receptors that might be involved in regulation of reproductive processes of P. trituberculatus. In the central nervous system transcriptome data, 47 neuropeptide transcripts were identified. In further analyses, the tissue expression profile of 32 putative neuropeptide-encoding transcripts was estimated. Results showed that the 32 transcripts were expressed in the central nervous system and 23 of them were expressed in the ovary. A total of 47 GPCR-encoding transcripts belonging to two classes were identified, including 39 encoding GPCR-A family and eight encoding GPCR-B family. In addition, we assessed the tissue expression profile of 33 GPCRs (27 GPCR-As and six GPCR-Bs) transcripts. These GPCRs were found to be widely expressed in different tissues. Similar to the expression profiles of neuropeptides, 20 of these putative GPCR-encoding transcripts were also detected in the ovary. This is the first study to establish the identify of neuropeptides and their GPCRs in P. trituberculatus, and provide information for further investigations into the effect of neuropeptides on the physiology and behavior of decapod crustaceans.
RESUMO
Vascular calcification was an independent risk of cardiovascular and cerebrovascular diseases (CCDs). Studies reported that conditioned media of choroid plexus epithelium cells (CPECs-CM) showed potential neuroprotective effects. However, the protective effect of CPECs-CM against vascular calcification (VC) has not been reported yet. Herein, high phosphate (HPi)-induced calcification model in mouse aortic vascular smooth muscle cells (MOVAS) was established, and the protective effects and underlying mechanism of CPECs-CM against HPi-induced calcification were explored. The results indicated that CPEC cells were successfully isolated and cultured, and CPECs-CM co-treatment significantly inhibited HPi-induced calcification of MOVAS cells through blocking alkaline phosphatase activity and expression. CPECs-CM co-treatment also suppressed reactive oxide species-mediated DNA damage in HPi-treated MOVAS cells. Moreover, dysfunction of MAPKs and PI3K/AKT pathways both contributed to HPi-induced calcification of MOVAS cells, and CPECs-CM co-treatment attenuated HPi-induced calcification by normalizing MAPKs and PI3K/AKT expression. Taken together, our findings provide evidence that CPECs-CM had the potential to inhibit vascular calcification with potent application in chemoprevention and chemotherapy of human CCD.
RESUMO
Epitaxial growth of aluminum gallium oxide is important for forming heterojunctions on Ga2O3 for high power electronics applications. We use density functional theory to explore the co-adsorption of Al, Ga, and O adatoms on the Ga2O3(010) surface and the surface reconstructions during the growth of the alloy. We find that Al can adsorb in tetrahedral sites in many of the reconstructions. The migration barrier escaping from a tetrahedral site to an octahedral site is 1.72 eV for an Al adatom and 0.56 eV for a Ga adatom, indicating that Al diffusion is much more restricted than Ga diffusion on the surface. Our findings indicate that kinetic limitations are responsible for Al occupying both octahedral and tetrahedral sites in (AlxGa1-x)2O3, in spite of the fact that thermodynamically the octahedral site is preferred.
RESUMO
The insulin-like androgenic gland hormone (IAG) is mainly produced in the androgenic gland (AG) of the male crustaceans and is a crucial regulator in male sexual differentiation. In the current study, the full-length cDNA of IAG in the swimming crab, Portunus trituberculatus (Pt-IAG), was cloned and characterized. Similar to other reported IAGs, the deduced amino acid sequence of Pt-IAG consists of signal peptide, B chain, C peptide, and A chain, containing six conserved cysteines that form two interchain disulfide bonds and one intra-B chain disulfide bond. Tissue distribution analysis suggested that the Pt-IAG cDNA was highly expressed in the AG and was slightly expressed in several other tissues. A short-term silencing of PtIAG with double-stranded RNA was found to reduce the transcript levels of insulin receptor (Pt-IR) and insulin-like growth factor-binding protein (Pt-IGFBP), suggesting the Pt-IAG might perform its biological function through the insulin family-based signaling system. Bilateral eyestalk ablation (ESA) induced the expression of Pt-IAG in the AG at 4 and 7 days after surgery, while the transcript levels of Pt-IR in the AG and testis and Pt-IGFBP in the muscle, testis, and thoracalia ganglia were significantly decreased from 1 day after surgery. The results suggested that the Pt-IR and Pt-IGFBP might also be the targets of eyestalk neuropeptides and responded to the ESA independent of IAG regulation.
Assuntos
Braquiúros/metabolismo , Insulina/metabolismo , Diferenciação Sexual/genética , Transdução de Sinais/fisiologia , Testículo/metabolismo , Animais , Braquiúros/genética , MasculinoRESUMO
The unique two-dimensional structure and chemical properties of graphene oxide (GO) provide a convenient method for preparing novel membranes. In this study, GO membranes were prepared through filtration by a pressure-assisted self-assembly method involving the cross-linking of three diamine monomers on a polyethersulfone (PES) support. The different small molecular diamines, ethylenediamine, butanediamine, and p-phenylenediamine, were introduced as cross-linking agents to investigate the effect of diamine on the properties of GO membranes. The hydrophobic substances ibuprofen, gemfibrozil, and triclosan were selected as target pharmaceuticals and personal care products (PPCPs). The adsorption and molecular sieving activities of PPCPs by cross-linked GO membranes at a pH of 3 were investigated. The permeate water was analyzed for dissolved organic carbon, ultraviolet absorption at 254 nm, molecular weight distribution, and fluorescence excitation-emission matrices. The results showed that the removal of hydrophobic PPCPs by GO membranes was mainly due to their adsorption and molecular sieving activities. Adsorption was mainly determined by the hydrophilic and hydrophobic properties of the membranes and PPCPs. The interception effect was mainly determined by the interlayer spacing between the GO membranes and the molecular weight and steric hindrance of the PPCPs. A smaller spacing of the GO membrane layers resulted in greater steric hindrance and a higher removal rate.
RESUMO
Sex-lethal (Sxl) gene operates as a master switch of sexual differentiation in Drosophila melanogaster. In this study, we cloned and characterized the full-length cDNA of Sxl in mud crab (Scylla paramamosain) (SpSxl). The deduced amino acid sequence of SpSxl contained two RNA-binding motifs (RRM), namely RRM1 and RRM2. The SpSxl mRNA levels were abundant in the androgenic glands of the male crab, implying its potential role in male sexual development. This hypothesis was supported by the RNAi experiment, revealing that the injection of SpSxl dsRNA in vivo caused an increase in the expression of SpIAG, which is a key gene of male sexual differentiation in crustaceans. The interference result of SpTra-2 suggested that SpSxl and SpTra-2 may be involved in sex-differentiation by direct or indirect regulation of SpIAG gene. The eye stalk ablation (ESA) experiments further confirmed that SpSxl could not regulate SpIAG through eyestalk neuropeptide, implying other regulation pathways. In addition, treatment with SpSxl dsRNA had no effects on SpDmrt expression, suggesting that sex determination in S. paramamosain is different from that in D. melanogaster.
Assuntos
Braquiúros/crescimento & desenvolvimento , Braquiúros/genética , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Desenvolvimento Sexual/genética , Animais , Ontologias Biológicas , Regulação da Expressão Gênica no Desenvolvimento , RNA Mensageiro/genética , Diferenciação Sexual/genéticaRESUMO
The valence-to-core (V2C) portion of x-ray emission spectroscopy (XES) measures the electron states close to the Fermi level. These states are involved in bonding, thus providing a measure of the chemistry of the material. In this article, we show the V2C XES spectra for several niobium compounds. The Kßâ³ peak in the V2C XES results from the transition of a ligand 2s electron into the 1s core-hole of the niobium, a transition allowed by hybridization with the niobium 4p. This location in energy of this weak peak shows a strong ligand dependence, thus providing a sensitive probe of the ligand environment about the niobium.
RESUMO
The confinement of noble gases on nanostructured surfaces, in contrast to bulk materials, at non-cryogenic temperatures represents a formidable challenge. In this work, individual Ar atoms are trapped at 300 K in nano-cages consisting of (alumino)silicate hexagonal prisms forming a two-dimensional array on a planar surface. The trapping of Ar atoms is detected in situ using synchrotron-based ambient pressure X-ray photoelectron spectroscopy. The atoms remain in the cages upon heating to 400 K. The trapping and release of Ar is studied combining surface science methods and density functional theory calculations. While the frameworks stay intact with the inclusion of Ar atoms, the permeability of gasses (for example, CO) through them is significantly affected, making these structures also interesting candidates for tunable atomic and molecular sieves. These findings enable the study of individually confined noble gas atoms using surface science methods, opening up new opportunities for fundamental research.
RESUMO
A kind of dealloyed nanoporous gold (NPG)/ultrathin CuO film nanohybrid for non-enzymatic glucose sensing has been prepared by a simple, in-situ, time-saving and controllable two-step electrodeposition. The three-dimensional and bicontinuous nanoporous structure of the nanocomposites have been characterized by scanning electron microscope (SEM) and transmission electron microscopy (TEM), and the electrochemical tests have been estimated by cyclic voltammetry and single potential step chronoamperometry (SPSC). The optimal NPG/CuO electrode exhibits great electrocatalytic activity towards glucose oxidation and also shows obvious linear response to glucose up to 12 mM with a high sensitivity of 374.0 µA cm(-2)mM(-1) and a good detection limit of 2.8 µM (S/N=3), as well as strong tolerance against chloride poisoning and interference of ascorbic acid and uric acid.
Assuntos
Técnicas Biossensoriais , Cobre/química , Glucose/análise , Glucose/química , Ouro/química , Nanoestruturas/química , Ácido Ascórbico/química , Técnicas Eletroquímicas , Eletroquímica , Galvanoplastia , Humanos , Limite de Detecção , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Nanocompostos , Nanotecnologia , Nanotubos de Carbono/química , Porosidade , Ácido Úrico/químicaRESUMO
Nanoporous gold (NPG) based biosensors have been constructed by covalently immobilizing glucose oxidase (GOx) onto self-assembled monolayers (SAMs). With p-benzoquinone (BQ) as a mediator, diffusion behavior and amperometric biosensor performance are evaluated by electrochemical characterization. The enzyme modified electrodes are demonstrated to show a thickness-sensitive behavior. Compared with planar polycrystalline gold, the unique porous structure of NPG has also been characterized via an electrochemical surface reconstruction process. Single-crystal gold-like electrochemical behavior on NPG and a comprehensive understanding of its impacts on sensor performance have been proposed.
Assuntos
Técnicas Biossensoriais/métodos , Glucose/análise , Ouro/química , Nanoporos , Aspergillus niger/enzimologia , Benzoquinonas/química , Técnicas Biossensoriais/instrumentação , Difusão , Eletroquímica , Eletrodos , Glucose Oxidase/metabolismo , HumanosRESUMO
We report a simple, one-step synthesis of hybrid film by electropolymerizing 3,4-ethylenedioxythiophene (EDOT) on nanoporous gold (NPG) for applications in amperometric glucose biosensors. The enzyme, glucose oxidase (GOx), is entrapped into poly(3,4-ethylenedioxythiophene) (PEDOT) matrix, simultaneously. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) studies show the NPG preserve its original bicontinuous nanoporous structure and the PEDOT film grows uniformly with a thickness of ~10 nm. The modified electrodes have been investigated by cyclic voltammetry (CV) and single potential step chronoamperometry (SPSC). The influence of PEDOT film's thickness has been explored to optimize sensor behaviors. Mediated by p-benzoquinone (BQ), the calibration curves have been obtained by applying relatively low constant potential of 200 mV (vs. SCE). The NPG/PEDOT/GOx (2CVs) biosensor exhibits high sensitivity of 7.3 µA mM(-1) cm(-2) and a wide linear range of 0.1-15 mM, making it suitable for reliable analytic applications.