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1.
Anal Chem ; 94(3): 1742-1751, 2022 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-35026109

RESUMO

Here, a label-free perovskite-based photoelectrochemical (PEC) aptasensor was rationally designed for the displacement assay of dibutyl phthalate (DBP), a well-known endocrine disruptor, with the aid of cetyltrimethylammonium bromide (CTAB). In this method, CTAB significantly enhanced the PEC response and humidity resistance of the CH3NH3PbI3 perovskite by forming a protecting layer and passivating the X- and A-sites vacancies of CH3NH3PbI3. In addition, CTAB facilitated the immobilization of an aptamer through van der Waals and hydrophobicity forces, as well as the electrostatic interactions between the phosphate group of the aptamer and the cationic group of CTAB. When exposed to DBP in the affinity solution, the DBP aptamer was released from the electrode because the affinity between DBP and its aptamer competes with the interaction of the aptamer and CTAB. The displacement of the aptamer from the perovskite surface relieves the block effect and thus enhances the photoelectric signal of perovskite. By virtue of the good photoelectrochemical characters of CH3NH3PbI3 and the specific recognition ability of aptamer, the linear range of the PEC sensor was 1.0 × 10-13 to 1.0 × 10-8 M and the detection and quantification limits were down to 2.5 × 10-14 and 8.2 × 10-14 M (S/N = 3), respectively. This work offers a novel strategy for designing aptasensors for the detection of various targets and exhibits the marvelous potential of organic-inorganic perovskite in the field of PEC analysis.

2.
Analyst ; 146(20): 6178-6186, 2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34553726

RESUMO

This work designed a novel dioctyl phthalate (DOP) photoelectrochemical (PEC) sensor based on a molecularly imprinted polymer (MIP) modified Cu3(BTC)2@Cu2O heterostructure. In this work, a metal organic framework (MOF), Cu3(BTC)2, was coated on Cu2O through a simple immersion method to form a Cu3(BTC)2@Cu2O heterostructure. The heterostructure exhibited strong light adsorption ability, good stability and enhanced photocurrent under visible light irradiation. Using the Cu3(BTC)2@Cu2O heterostructure as the photoelectric converter, a PEC sensor was constructed by imprinting DOP on the heterostructure. Under the optimal experimental conditions, the PEC sensor showed a wide linear range from 25.0 pM-0.1 µM and a low detection limit of 9.15 pM. This method with good sensitivity, stability, selectivity and reproducibility in actual sample analyses showed promising applications of the MOF-based heterostructure in photoelectrochemical analysis fields.

3.
Talanta ; 225: 122050, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33592772

RESUMO

Herein, we reported the introduction of carbon nanodots (CNDs) and polyvinylidene fluoride (PVDF) as additives into perovskite CH3NH3PbI3 through in situ synthesis to prepare PVDF-CH3NH3PbI3@CNDs composite, which demonstrated improved water tolerance and mechanical stability. The application of PVDF-CH3NH3PbI3@CNDs for photoelectrochemical sensing was then explored. A molecularly imprinted polymer (MIP) that could specifically recognize cholesterol (CHO) was anchored to PVDF-CH3NH3PbI3@CNDs via a simple thermal polymerization process, followed by elution with hexane. A label-free and sensitive photoelectrochemical method for CHO detection was achieved by using the MIPs@PVDF-CH3NH3PbI3@CNDs platform. The detection limit for CHO was 2.1 × 10-14 mol/L, lower than most of the existing CHO detection methods. In our perception, this platform can be extended to numerous other analytes. This research result may provide a new understanding to improve the performance and broaden the application range of organic-inorganic perovskites.


Assuntos
Carbono , Polímeros , Compostos de Cálcio , Colesterol , Óxidos , Titânio
4.
Sleep Breath ; 25(4): 1875-1884, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33486668

RESUMO

PURPOSE: REM-related obstructive sleep apnea (REM-OSA), as defined using revised apnea-hypopnea index (AHI) criteria, might represent a specific OSA phenotype. However, there is a lack of data on outcomes of treatment in this population. This study evaluated the effects of CPAP treatment over 12 months on clinical outcomes for patients with the polysomnography phenotype of REM-OSA. METHODS: We conducted a prospective observational study with the following inclusion criteria: subjective sleepiness and diagnostic polysomnography demonstrating AHIREM≥15 events/h, AHINREM<5 events/h, and ≥ 30 min of REM sleep. Clinical outcomes assessed included Epworth Sleepiness Scale (ESS), psychomotor vigilanc test reaction time (PVT-RT), and CPAP adherence at baseline, 1, 3, 6, and 12 months; Functional Outcomes of Sleep Questionnaire (FOSQ) and Depression Anxiety Stress Scales (DASS-21) at baseline, 1, 3 and 12 months. The reason is the first 3 outcomes (ESS, PVT, adherence) were assessed at baseline, 1, 3, 6, and 12 months, while the next 2 outcomes (FOSQ, DASS) were assessed at baseline, 1, 3, and 12 months. The edited version is not as clear in separating these outcomes into 2 groups; Functional Outcomes of Sleep Questionnaire (FOSQ); and Depression Anxiety Stress Scales (DASS-21) at baseline, 1, 3, and 12 months. Linear mixed effects models were used to investigate the joint effects of time and average CPAP adherence on our outcomes of interest. RESULTS: Twenty participants completed a minimum of 1 month of CPAP treatment and were included for analysis. During the trial, 8 participants discontinued CPAP (4 before 3 months, 1 before 6 months, 3 before 12 months), and 19 participants completed 12 months of treatment. Baseline ESS was elevated at 12.6 units. Average CPAP usage for all 27 participants over 12 months was 2.9 ± 2.4 h. There was a significant decrease in ESS and increase in FOSQ at all time points, and the decrease in ESS was only seen in the CPAP-adherent subgroup. Decreases in DASS-21 and PVT-RT were not sustained. CONCLUSIONS: CPAP treatment in sleepy patients with moderate to severe REM-OSA is associated with reduced sleepiness and improved quality of life. TRIAL REGISTRATION: The trial was registered in the Australian New Zealand Clinical Trials Registry: ACTRN12620000576921, 18/05/2020 (retrospectively registered).

5.
Anal Methods ; 12(31): 3892-3900, 2020 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-32716416

RESUMO

Flexible sensors are of considerable interest for the development of wearable smart miniature devices. This work reported a flexible electrochemical platform based on reduced graphene oxide (rGO) for the detection of salicylic acid (SA). The free-standing and flexible rGO electrode was prepared via a simple extruded process. Dynamic mechanical deformation and bending studies illustrated the resilience and compliance of the flexible electrode against extreme mechanical deformations. Quantitative analysis of SA was performed by using differential pulse voltammetry (DPV) with this flexible rGO electrode. Linearity ranges for SA were obtained from 1.0 × 10-10 M to 1.0 × 10-5 M with the detection limit of 2.3 × 10-11 M (S/N = 3). This strategy provided a new insight into the design and application of flexible electrodes. It will extend the applications of rGO in sensing, bio-electronics and lab-on-chip devices.

6.
Mol Med Rep ; 20(3): 2954-2962, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31322231

RESUMO

A number of studies have linked abnormalities in the function of the serotonergic and noradrenergic systems to the pathophysiology of depression. It has been reported that selective serotonin reuptake inhibitors promote the expression of tryptophan hydroxylase (TPH), which is involved in the synthesis of serotonin. However, limited evidence of TPH alteration has been found in selective serotonin and noradrenaline reuptake inhibitors (SNRIs), and more key enzymes need to be investigated. The aim of the present study was to determine whether venlafaxine (VLX; a classical SNRI) regulates TPH and other key enzymes responsible for the synthesis and metabolism of monoaminergic transmitters in rats with chronic unpredictable stress (CUS). The present results suggested that CUS­exposed rats exhibited decreased locomotor activity in the open­field test and increased immobility time in the forced swim test, as compared with the controls. Pretreatment with VLX (20 mg/kg) significantly increased locomotor activity and reduced immobility time in the CUS­exposed rats. In addition, VLX (20 mg/kg) treatment prevented the CUS­induced reduction in tyrosine hydroxylase and TPH expression in the cortex and hippocampus. Furthermore, VLX alleviated the CUS­induced oxidative stress in the serum, cortex and hippocampus. However, VLX administration did not have an effect on indoleamine­2,3­dioxygenase overexpression in the hippocampus. It was therefore concluded that the regulation of abnormalities in the synthesis and metabolism of monoaminergic transmitters may be associated with the antidepressant effects of VLX, suggesting that multimodal pharmacological treatments can efficiently treat depression.


Assuntos
Antidepressivos de Segunda Geração/uso terapêutico , Monoaminas Biogênicas/metabolismo , Depressão/tratamento farmacológico , Triptofano Hidroxilase/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo , Cloridrato de Venlafaxina/uso terapêutico , Animais , Antidepressivos de Segunda Geração/farmacologia , Comportamento Animal/efeitos dos fármacos , Depressão/etiologia , Depressão/fisiopatologia , Hipocampo/efeitos dos fármacos , Hipocampo/fisiopatologia , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Masculino , Monoaminoxidase/metabolismo , Ratos Sprague-Dawley , Estresse Fisiológico/efeitos dos fármacos , Cloridrato de Venlafaxina/farmacologia
7.
Neuroreport ; 30(4): 255-261, 2019 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-30640193

RESUMO

Venlafaxine (VEN) is a widely used antidepressant as a serotonin-reuptake and norepinephrine-reuptake inhibitor. It is used primarily in depression, especially with generalized anxiety disorder or chronic pain. This medicine is of interest because its mechanisms involved multiple aspects. In the current study, the antidepressant action of VEN was investigated by studying the histone acetylation and expression of tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH) in rats exposed to chronic unpredicted stress (CUS) for 28 days. Male Sprague-Dawley rats were divided into a control group, VEN-treated control group, CUS group, and VEN-treated CUS group. VEN (23.4 mg/kg once daily) was administered to rats by intragastric gavage, whereas the same volume of vehicle was given to rats in the control and model groups. Rat behaviors, acetylated H3 at lysine 9 (acH3K9), acetylated H3 at lysine 14 (acH3K14), acetylated H4 at lysine 12 (acH4K12), histone deacetylase 5, and TH and TPH expression in the hippocampus were determined. Chronic VEN treatment significantly relieved the anxiety- and depression-like behaviors, prevented the increase of histone deacetylase 5 expression and decrease of acH3K9 level, and promoted TH and TPH protein expression in the hippocampus of CUS rats. The results suggest that the preventive antidepressant mechanism of VEN is partly involved in the blocking effects on histone de-acetylated modification and then increasing TH, TPH expression.


Assuntos
Antidepressivos/farmacologia , Hipocampo/efeitos dos fármacos , Triptofano Hidroxilase/efeitos dos fármacos , Tirosina 3-Mono-Oxigenase/efeitos dos fármacos , Cloridrato de Venlafaxina/farmacologia , Acetilação/efeitos dos fármacos , Animais , Depressão/metabolismo , Hipocampo/metabolismo , Histonas/efeitos dos fármacos , Histonas/metabolismo , Masculino , Ratos , Ratos Sprague-Dawley , Triptofano Hidroxilase/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo
8.
Neuroreport ; 26(18): 1145-50, 2015 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-26512932

RESUMO

Depression is a common worldwide mental disorder whose etiology remains unclear; there is also a lack of effective therapeutic agents. Sodium valproate (VPA) is a traditional antiepileptic drug with mood-stabilization effect and is increasingly being used to treat bipolar disorders and depression, but its antidepressant mechanism remains unknown. The aim of the present study was to investigate the possible mechanisms of antidepressant action by studying malondialdehyde level, catalase, and superoxide dismutase activities in the serum and the mRNA and protein expression of tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH) in the prefrontal cortex of rats exposed to chronic unpredicted stress (CUS). Male Sprague-Dawley rats were used to establish a depression model by CUS. VPA (300 mg/kg once daily) and an equivalent volume of vehicle were administered to rats by an intragastric gavage. Rat behaviors, serum malondialdehyde level, serum catalase and superoxide dismutase activities, and the mRNA and protein expressions of TH and TPH in the prefrontal cortex were determined. The results showed that VPA treatment led to a significant decrease in depression-like behaviors, improvement in oxidative stress imbalance, and enhancement of TH, TPH mRNA, and protein expression in stressed rats, but failed to show any significant changes in control rats. This could indicate that the antidepressant mechanism of VPA is perhaps linked to upregulation of TH and TPH expression and inhibition of oxidative damage in CUS rats.


Assuntos
Antidepressivos/administração & dosagem , Comportamento Animal/efeitos dos fármacos , Depressão/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Estresse Psicológico/metabolismo , Triptofano Hidroxilase/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo , Ácido Valproico/administração & dosagem , Animais , Catalase/sangue , Depressão/prevenção & controle , Masculino , Malondialdeído/sangue , Córtex Pré-Frontal/efeitos dos fármacos , Córtex Pré-Frontal/metabolismo , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Superóxido Dismutase/sangue
9.
Asian Pac J Cancer Prev ; 16(4): 1343-8, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25743796

RESUMO

Human UHRF1 (ubiquitin-like PHD and RING finger domain-containing 1) has been reported to be over-expressed in many cancers, but its role in ovarian cancer remains elusive. Here, we determined whether knockdown of UHRF1 by lentivirus-mediated shRNA could inhibit ovarian cancer cell growth. Lentivirus- mediated short hairpin RNAs (lv-shRNAs-UHRF1) were designed to trigger the gene silencing RNA interference (RNAi) pathway. The efficiency of lentivirus-mediated shRNA infection into HO-8910 and HO-8910 PM cells was determined using fluorescence microscopy to observe lentivirus-mediated GFP expressionand was confirmed to be over 80 percent. UHRF1 expression in infected HO-8910 and HO-8910 PM was evaluated by real-time PCR and Western blot analysis. The Cell Counting Kit-8 (CCK-8) assay was used to measure cell viability; flow cytometry and Hoechst 33342 assay was applied to measure cell cycle arrest and apoptosis. Cell invasion was assessed using transwell chambers. Our results demonstrated that the loss of UHRF1 promoted HO-8910 and HO-8910 PM cell apoptosis, while inhibiting cell proliferation. In addition, UHRF1 knockdown significantly inhibited the invasion of human ovarian cancer cells. In the present study, we also showed that depleting HO-8910 cells of UHRF1 caused activation of the DNA damage response pathway, with the cell cycle arrested in G2/M-phase. The DNA damage response in cells depleted of UHRF1 was illustrated by phosphorylation of CHK (checkpoint kinase) 2 on Thr68, phosphorylation of CDC25 (cell division control 25) on Ser 216 and phosphorylation of CDK1 (cyclin-dependent kinase 1) on Tyr 15.


Assuntos
Biomarcadores Tumorais/genética , Proteínas Estimuladoras de Ligação a CCAAT/antagonistas & inibidores , Movimento Celular , Proliferação de Células , Lentivirus/genética , Neoplasias Ovarianas/prevenção & controle , RNA Interferente Pequeno/genética , Apoptose , Western Blotting , Proteínas Estimuladoras de Ligação a CCAAT/genética , Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Ciclo Celular , Feminino , Citometria de Fluxo , Humanos , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/patologia , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células Tumorais Cultivadas , Ubiquitina-Proteína Ligases
10.
Neuroreport ; 25(17): 1338-43, 2014 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-25304496

RESUMO

Sodium valproate (VPA) is widely used as an antiepileptic agent and mood stabilizer. In recent years, VPA has been increasingly used as a psychotherapeutic drug to treat depression. In this article, a possible antidepressant mechanism of VPA was investigated by studying the expression and therefore the involvement of tryptophan hydroxylase, serotonin transporter (5-HTT), monoamine oxidase-A (MAO-A), and indoleamine 2, 3-dioxygenase (IDO) in rats exposed to chronic unpredicted stress. Male Sprague-Dawley rats were divided into four groups: the vehicle-treated control group (CG), the VPA-treated control group (VPAC), the vehicle-treated model group (MG), and the VPA-treated model group (VPAM). VPA (300 mg/kg once daily) was administered to VPAC and VPAM rats by means of intragastric gavage while an equivalent volume of vehicle was given to vehicle-treated CG and MG rats. Rat behavior and expression of tryptophan hydroxylase, 5-HTT, MAO-A, and IDO in the hippocampus were determined. A significant reduction in depression-like behaviors was observed with an upregulation of 5-HTT expression and a downregulation of MAO-A and IDO expression in VPAM rats, compared with MG rats. The results may suggest that the antidepressant mechanism of VPA is partly related to elevated serotonin level and its reuse in the vesicles of presynaptic nerve endings.


Assuntos
Antidepressivos/farmacologia , Transtorno Depressivo/tratamento farmacológico , Transtorno Depressivo/fisiopatologia , Animais , Doença Crônica , Modelos Animais de Doenças , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Masculino , Monoaminoxidase , RNA Mensageiro/metabolismo , Distribuição Aleatória , Ratos Sprague-Dawley , Proteínas da Membrana Plasmática de Transporte de Serotonina/metabolismo , Estresse Psicológico , Triptofano Hidroxilase/metabolismo , Ácido Valproico/farmacologia
11.
Exp Biol Med (Maywood) ; 239(3): 330-6, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24495952

RESUMO

Histone acetylation has been linked to depression, the etiology of which involves many factors such as genetics, environments, and epigenetics. The aim of the present study was to investigate whether it was associated with epigenetic histone modification and gene expression of enzymes responsible for the biosynthesis of norepinephrine and serotonin in rat depression model induced by chronic unpredictable stress (CUS). Eight-week-old male Sprague-Dawley rats were exposed to CUS over 28 days. It was shown that the CUS-induced rats displayed remarked anxiety- and depression-like behavior with weakened locomotor activity in open field test and prolonged immobility in forced swimming test. Western blot revealed that CUS led to significant decrease in acetylation of H3 at Lysine 9 (K9) and H4 at Lysine 12 (K12) with obviously increasing histone deacetylases 5 (HDAC5) expression in hippocampus of CUS-induced rats. Meanwhile, there was an obviously decreased expression of tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH) both at protein and mRNA levels. Administration of sodium valproate (VPA), a histone deacetylase 5 (HDAC5) inhibitor, not only significantly relieved the anxiety- and depression-like behaviors of CUS-induced rats but also clearly blunted decrease of H3(K9) and H4(K12) acetylation and expression of TH and TPH, and prevented increase of HDAC5 expression. The results indicate that there exists possible interrelation between TH and TPH gene expression and epigenetic histone acetylation in CUS-induced depressive rats, which at least partly contributes to the etiology of depression.


Assuntos
Depressão/enzimologia , Epigênese Genética , Estresse Psicológico/complicações , Triptofano Hidroxilase/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo , Acetilação/efeitos dos fármacos , Animais , Ansiedade/enzimologia , Ansiedade/etiologia , Ansiedade/genética , Depressão/etiologia , Depressão/genética , Modelos Animais de Doenças , Expressão Gênica , Hipocampo/metabolismo , Inibidores de Histona Desacetilases/farmacologia , Histona Desacetilases/biossíntese , Histona Desacetilases/metabolismo , Histonas/metabolismo , Masculino , Norepinefrina/biossíntese , Norepinefrina/genética , RNA Mensageiro/biossíntese , Ratos , Ratos Sprague-Dawley , Serotonina/genética , Triptofano Hidroxilase/biossíntese , Triptofano Hidroxilase/genética , Tirosina 3-Mono-Oxigenase/biossíntese , Tirosina 3-Mono-Oxigenase/genética , Ácido Valproico/farmacologia
12.
Neuroreport ; 25(4): 205-10, 2014 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-24128869

RESUMO

Sodium valproate (VPA) is an antiepileptic drug and mood stabilizer used to treat bipolar disorders. Recently, other psychiatric uses for VPA have been based on its antidepressive and neuroprotective effects. In the current work, the antidepressive mechanism of VPA was investigated by studying the expression of brain-derived neurotrophic factor (BDNF) and hypothalamic-pituitary-adrenal axis function in rats exposed to a protocol of chronic unpredicted stress (CUS). Male Sprague-Dawley rats were divided into a vehicle-treated control group (no CUS+vehicle), a VPA-treated control group (no CUS+VPA), a vehicle-treated model group (CUS+vehicle), and a VPA-treated model group (CUS+VPA). VPA (300 mg/kg once daily) was administered to rats (no CUS+VPA and CUS+VPA) by an intragastric gavage, whereas the same volume of vehicle was administered to rats in the no CUS+vehicle and CUS+vehicle groups. Rat behavior, serum corticosterone level, and expression of BDNF in the hippocampus and corticotrophin-releasing factor in the hypothalamus were determined. Compared with the CUS+vehicle rats, the CUS+VPA rats showed a significant relief in depression-like behaviors and a decrease in the corticosterone level and corticotropin-releasing factor expression with increasing expression of BDNF. The results suggest that the antidepressive effect of VPA is at least partly related to improving hypothalamic-pituitary-adrenal axis function and elevating the expression of BDNF.


Assuntos
Antidepressivos/farmacologia , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Hormônio Liberador da Corticotropina/metabolismo , Transtorno Depressivo/tratamento farmacológico , Transtorno Depressivo/metabolismo , Ácido Valproico/farmacologia , Animais , Corticosterona/sangue , Expressão Gênica/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Hipotálamo/efeitos dos fármacos , Hipotálamo/metabolismo , Masculino , Testes Neuropsicológicos , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Estresse Psicológico/tratamento farmacológico , Estresse Psicológico/metabolismo , Análise e Desempenho de Tarefas
13.
J Agric Food Chem ; 61(8): 1810-7, 2013 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-23373873

RESUMO

Based on the synergetic effect of the electrochemical accumulation process and the signal amplification of enzymes, a new sensitive method has been developed for the detection of subnanomolar melamine. There are two steps involved in the sensor construction process: (1) accumulation of melamine on an electrode by cyclic voltammetric method and (2) chemical coupling of horseradish peroxidase (HRP) with the accumulated melamine through the linkage of glutaraldehyde. The coupled HRP catalyzes the oxidation of guaiacol to generate an amber-colored product. Quantitative analysis of melamine is performed by measuring the absorption intensities of the colored product. Under the optimal conditions, the method showed a wide linearity in the concentration range from 1.0 × 10(-11) to 1.0 × 10(-8) M for melamine detection. Moreover, it has been successfully applied to detect melamine in different infant formula powders and fish feed samples.


Assuntos
Ração Animal/análise , Colorimetria/métodos , Técnicas Eletroquímicas/métodos , Contaminação de Alimentos/análise , Fórmulas Infantis/química , Triazinas/análise , Técnicas Eletroquímicas/instrumentação , Peroxidase do Rábano Silvestre/química , Sensibilidade e Especificidade
14.
J Agric Food Chem ; 59(23): 12629-34, 2011 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-22077283

RESUMO

A rapid synchronous spectrofluorimetric method was first developed for the simultaneous determination of folic acid and riboflavin in nutrimental beverages. Folic acid could be detected by using H(2)O(2) plus Cu(II) as oxidation system to produce pterine-6-carboxylic acid, which had strong fluorescence in aqueous solution, and riboflavin itself was obviously fluorescent. Various operational parameters were thoroughly discussed in terms of their effects on the fluorescence signals, including instrumental parameters, concentration of the oxidation system, and pH. Under optimum conditions, the calibration curves were linear in the ranges of 100-250 µg/L for folic acid and 1-250 µg/L for riboflavin, and the detection limits were 2.0 and 0.014 µg/L, respectively. In addition, this method was applied to the determination of folic acid and riboflavin in nutrimental beverages with satisfactory results.


Assuntos
Bebidas/análise , Ácido Fólico/análise , Riboflavina/análise , Espectrometria de Fluorescência/métodos , Peróxido de Hidrogênio , Concentração de Íons de Hidrogênio , Valor Nutritivo , Oxirredução , Controle de Qualidade
15.
Talanta ; 86: 227-32, 2011 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-22063535

RESUMO

An electrochemical method has been successfully demonstrated for sensitive determination of azithromycin (Azi) with room temperature ionic liquid (IL) of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF(6)) - graphene (Gr) composite modified glassy carbon electrode (GCE). The cyclic voltammetric results indicate that Gr/IL/GCE can remarkably enhance electrocatalytic activity towards the oxidation of Azi in neutral solutions. Azi produce an anodic peak at about 0.82 V at this electrode. The electrocatalytic behavior was further exploited as a sensitive detection scheme for the Azi determination by differential-pulse voltammetry (DPV). Under optimized conditions, the concentration range and detection limit were 0.49-28.57 µg ml(-1) and 0.19 µg ml(-1) (S/N=3) respectively for Azi. The method was successfully applied assay of the drug in the pharmaceutical dosage forms.


Assuntos
Azitromicina/química , Técnicas Eletroquímicas/métodos , Grafite/química , Eletrodos Íon-Seletivos , Líquidos Iônicos/química
16.
Zhongguo Dang Dai Er Ke Za Zhi ; 12(12): 936-9, 2010 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-21172126

RESUMO

OBJECTIVE: To study the risk factors for neonatal ventilator-associated pneumonia (VAP) and the changes of isolated pathogens in the last eight years. METHODS: The clinical data of 230 neonates who were admitted into the neonatal intensive care unit (NICU) and received mechanical ventilation for equal to or longer than 48 hrs in 2008 were retrospectively reviewed. The isolated pathogens were compared with those of eight years ago. RESULTS: The incidence of VAP (25.2%) in the year 2008 was lower than that of eight years ago (36.1%; P<0.05). The development of VAP was negatively correlated with the gestational age and the birth weight, but positively correlated with the duration of mechanical ventilation, intubation times, duration of hospitalization, presence of gastrointestinal bleeding and need for blood products transfusion. The main isolated pathogens were opportunistic antibiotics resistant bacteria, and the majority was gram negative bacilli (77%). The most frequently detected gram negative bacilli were Klebsiella (20%), Stenotrophomonas maltophilia (18%) and Acinetobacter (13%). Streptococcus mitis was the most frequently detected gram positive bacilli (14%). The distribution pattern of pathogens isolated in the same NICU eight years ago was somewhat different: Klebsiella (23%), Pseudomonas aeruginosa (17%), Acinetobacter (16%), Streptococcus mitis (11%), Fungi (1%) and Candida albicans (1%). CONCLUSIONS: The incidence of VAP is correlated with gestational age, birth weight, duration of mechanical ventilation and hospitalization, intubation times, presence of gastrointestinal bleeding and need for blood products transfusion. The main isolated pathogens are usually antibiotic resistant opportunistic bacteria. The detection rate of Stenotrophomonas maltophilia increased and that of Pseudomonas aeruginosa decreased when compared with eight years ago.


Assuntos
Bactérias Gram-Negativas , Pneumonia Associada à Ventilação Mecânica , Antibacterianos/uso terapêutico , Bactérias Gram-Negativas/isolamento & purificação , Humanos , Incidência , Recém-Nascido , Fatores de Risco
17.
Front Biosci (Elite Ed) ; 2: 339-50, 2010 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-20036882

RESUMO

Multilayer copper hexacyanoferrate (CuHCF) films bridged by cysteine monolayer protected copper clusters (CuMPCs) were prepared by the sequential electrochemical cyclcing and dipping process. Cyclic voltammetry, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the formation of the multilayer films. Cyclic voltammetric measurements indicated that the films grew exponentially with the increase of the layer numbers. AFM and SEM images revealed that the obtained films were thin and exhibited a three-dimensional structure. The nanostructured thin-film assemblies exhibited interesting catalytic properties that could be applied in important sensing and catalysis. Good catalytic activity and stability of the film modified electrode for hydrogen peroxide detection was studied.


Assuntos
Cobre/química , Eletroquímica/métodos , Ferrocianetos/química , Peróxido de Hidrogênio/isolamento & purificação , Nanoestruturas/química , Catálise , Química Analítica , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Nanoestruturas/ultraestrutura
18.
Electrophoresis ; 30(6): 1071-6, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19309008

RESUMO

Monolithic capillary columns were prepared by the reaction of a mixture of potassium silicate solution and formamide. The surface of the monolith was coated with a thin film formed by a sol-gel method to increase the surface area of the monolith and simultaneously covered with C8 as stationary phase for reversed-phase separation. The morphology of the monolithic column was investigated by SEM. Monolithic columns prepared in this manner showed high permeability and can be operated in capillary LC (CLC) mode at a pressure of 20 psi. PAHs were used to evaluate the separation performance of the stationary phase using CLC and pressurized CEC (pCEC). Efficiencies of 20 000 and 28 000 plates per meter for naphthalene were obtained in CLC and pCEC modes, respectively. Improvement in column efficiency and reduction in analysis time over CLC and improvement in operation facility and separation selectivity over CLC were found using pCEC mode.


Assuntos
Eletrocromatografia Capilar/métodos , Cromatografia Líquida/métodos , Dióxido de Silício/química , Géis/química , Microscopia Eletrônica de Varredura , Permeabilidade , Hidrocarbonetos Policíclicos Aromáticos/química , Reprodutibilidade dos Testes
19.
J Chromatogr A ; 1198-1199: 95-100, 2008 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-18538779

RESUMO

Monodispersed spherical gold particles synthesized and modified with n-octadecanethiol (C18-Au) were packed into a 100 microm I.D. capillary column and tested in capillary high-performance liquid chromatography (microHPLC). To the best of our knowledge, this represents the first report on the actual use of micron gold particles as stationary phase in a packed column microHPLC. As measured by scanning electron microscopy, the average diameter of these gold microspheres was 3.5 microm and the surface area, average pore diameter, and average pore volume were 49.4m(2)/g, 4.8 nm, and 0.12 cm(3)/g, respectively. The retention behavior of neutral compounds on the n-octadecanethiol-modified gold microspheres was investigated by separating a mixture of small organic compounds using microHPLC. The results from the experiments show that C18-Au behaves basically as a reversed phase. The test of chemical stability of the C18-Au stationary phase under alkaline condition demonstrates that it is stable with the flushing of a mobile phase at pH 12 for at least 140 h. The C18-Au particles are also mechanically strong enough to withstand pressure up to 52 MPa. The preliminary results in this work prove the feasibility of the fabrication of C18-Au micron particles as a novel stationary phase for packed column microHPLC.


Assuntos
Eletrocromatografia Capilar/métodos , Ouro/química , Microesferas , Compostos de Sulfidrila/química , Eletrocromatografia Capilar/instrumentação , Concentração de Íons de Hidrogênio
20.
Anal Chim Acta ; 609(1): 76-81, 2008 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-18243876

RESUMO

The octadecylamine-capped gold nanoparticles (ODA-Au-NPs) were prepared and directly used to coat the capillary wall. The hydrophobic coating acted as the stationary phase for open-tubular gas chromatography (OTGC). The ODA-Au-NPs can be adsorbed tightly onto the inner surface of fused silica capillary column via electrostatic interaction and enhanced interaction of van der Waals between gold nanoparticles and the capillary wall. Thus, the modification of the inner surface of capillary column by ODA-Au-NPs can be achieved simply by flushing the capillary with a solution of ODA-Au-NPs and the resulted ODA-Au-NPs coating is very stable. No perceptible degradation in the ODA-Au-NPs-based separation was observed after approximately 1900 sample runs. This type of columns also provided excellent chromatographic performances: high number of theoretical plates, outstanding run-to-run and column-to-column reproducibility, and high selectivity for a wide range of test mixtures. An efficiency of 2474 theoretical plates per meter for chlorobenzene was obtained on an ODA-Au-NPs-modified 1.6 m x 100 microm i.d. fused silica capillary column.


Assuntos
Aminas/química , Cromatografia Gasosa/métodos , Ouro/química , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Microscopia Eletrônica de Varredura , Temperatura
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