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1.
Mikrochim Acta ; 191(6): 316, 2024 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-38724679

RESUMO

An ultra-sensitive photoelectrochemical (PEC) sensor based on perovskite composite was developed for the determination of alkaline phosphatase (ALP) in human serum. In contrast to CsPbBr3 or Y6 that generated anodic current, the heterojunction of CsPbBr3/Y6 promoted photocarriers to separate and generated cathodic photocurrent. Ascorbic acid (AA) was produced by ALP hydrolyzing L-ascorbic acid 2-phosphate trisodium salt (AAP), which can combine with the holes on the photoelectrode surface, accelerating the transmission of photogenerated carriers, leading to enhanced photocurrent intensity. Thus, the enhancement of PEC current was linked to ALP activity. The PEC sensor exhibits good sensitivity for detection of ALP owing to the unique photoelectric properties of the CsPbBr3/Y6 heterojunction. The detection limit of the sensor was 0.012 U·L-1 with a linear dynamic range of 0.02-2000 U·L-1. Therefore, this PEC sensing platform shows great potential for the development of different PEC sensors.


Assuntos
Fosfatase Alcalina , Ácido Ascórbico , Técnicas Eletroquímicas , Eletrodos , Limite de Detecção , Óxidos , Processos Fotoquímicos , Titânio , Fosfatase Alcalina/química , Fosfatase Alcalina/sangue , Fosfatase Alcalina/metabolismo , Humanos , Técnicas Eletroquímicas/métodos , Técnicas Eletroquímicas/instrumentação , Ácido Ascórbico/química , Ácido Ascórbico/sangue , Ácido Ascórbico/análogos & derivados , Titânio/química , Óxidos/química , Compostos de Cálcio/química , Técnicas Biossensoriais/métodos
2.
Mikrochim Acta ; 191(6): 341, 2024 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-38795199

RESUMO

The construction of gating system in artificial channels is a cutting-edge research direction in understanding biological process and application sensing. Here, by mimicking the gating system, we report a device that easily synthesized single-glass micropipettes functionalized by three-dimensional (3D) DNA network, which triggers the gating mechanism for the detection of biomolecules. Based on this strategy, the gating mechanism shows that single-glass micropipette assembled 3D DNA network is in the "OFF" state, and after collapsing in the presence of ATP, they are in the "ON" state, at which point they exhibit asymmetric response times. In the "ON" process of the gating mechanism, the ascorbic acid phosphate (AAP) can be encapsulated by a 3D DNA network and released in the presence of adenosine triphosphate (ATP), which initiates a catalyzed cascade reaction under the influence of alkaline phosphatase (ALP). Ultimately, the detection of ALP can be responded to form the fluorescence signal generated by terephthalic acid that has captured hydroxyl radicals, which has a detection range of 0-250 mU/mL and a limit of detection of 50 mU/mL. This work provides a brand-new way and application direction for research of gating mechanism.


Assuntos
Trifosfato de Adenosina , Fosfatase Alcalina , DNA , Trifosfato de Adenosina/análise , Trifosfato de Adenosina/química , Trifosfato de Adenosina/metabolismo , Fosfatase Alcalina/metabolismo , Fosfatase Alcalina/química , DNA/química , Vidro/química , Técnicas Biossensoriais/métodos , Limite de Detecção , Ácido Ascórbico/química , Ácido Ascórbico/análogos & derivados
3.
J Agric Food Chem ; 72(20): 11629-11639, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38739462

RESUMO

Blueberries (Vaccinium section Cyanococcus) have a wealth of bioactive compounds, including anthocyanins and other antioxidants, that offer significant health benefits. Preserving these compounds and maintaining the sensory and nutritional qualities of blueberry products such as juice during cold market storage is critical to meet consumer expectations for nutritious, safe, and minimally processed food. In this study, we compared the effects of two preservation processing techniques, high-temperature short-time (HTST) and continuous flow high-pressure homogenization (CFHPH), on blueberry juice quality during storage at 4 °C. Our findings revealed that inlet temperature (Tin) of CFHPH processing at 4 °C favored anthocyanin retention, whereas Tin at 22 °C favored ascorbic acid retention. After 45 days of storage, CFHPH (300 MPa, 1.5 L/min, 4 °C) juice retained up to 54% more anthocyanins compared to control at 0 day. In contrast, HTST treatment (95 °C, 15 s) initially increased anthocyanin concentrations but led to their subsequent degradation over time, while also significantly degrading ascorbic acid. Furthermore, CFHPH (300 MPa, 4 °C) juice had significantly lower polyphenol oxidase activity (>80% less than control), contributing to the overall quality of the juice. This innovative processing technique has the potential to improve commercial blueberry juice, and help meet the rising demand for healthy and appealing food choices.


Assuntos
Antocianinas , Ácido Ascórbico , Mirtilos Azuis (Planta) , Temperatura Baixa , Armazenamento de Alimentos , Sucos de Frutas e Vegetais , Frutas , Antocianinas/química , Antocianinas/análise , Mirtilos Azuis (Planta)/química , Ácido Ascórbico/análise , Ácido Ascórbico/química , Sucos de Frutas e Vegetais/análise , Frutas/química , Pressão , Conservação de Alimentos/métodos , Conservação de Alimentos/instrumentação , Manipulação de Alimentos/métodos , Manipulação de Alimentos/instrumentação , Antioxidantes/química , Antioxidantes/análise
4.
Int J Biol Macromol ; 269(Pt 2): 132263, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38734332

RESUMO

Two low-molecular-weight polysaccharides (DPSP50 and DPSP70) were obtained using hydrogen peroxide-vitamin C (H2O2-Vc) treatment at 50 °C and 70 °C, respectively. Both DPSP50 and DPSP70 comprised the same six monosaccharides in different ratios, and their molecular weights (Mws) were 640 kDa and 346 kDa, respectively. Functional properties analyses demonstrated that DPSP50 and DPSP70 each had an excellent water holding capacity, oil absorption capacity, and emulsion properties, as well as shear-thinning characteristics and viscoelastic properties. Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopic assays confirmed the existence of α-, ß-pyranose rings and the same six sugar residues in DPSP50 and DPSP70. The results of Congo red test, scanning electron microscopy (SEM), and X-ray diffraction (XRD) demonstrated that DPSP50 and DPSP70 did not contain triple-helix conformations, but were amorphous aggregates with flake-like shape and rough surface. Additionally, both DPSP50 and DPSP70 showed strong anti-complementary activities through the classical pathway and the alternative pathway. The results support the potential utility of these degraded polysaccharides from strawberry fruits in functional foods and medicines.


Assuntos
Fragaria , Frutas , Polissacarídeos , Fragaria/química , Polissacarídeos/química , Polissacarídeos/farmacologia , Frutas/química , Peso Molecular , Monossacarídeos/análise , Monossacarídeos/química , Antioxidantes/química , Antioxidantes/farmacologia , Espectroscopia de Infravermelho com Transformada de Fourier , Emulsões/química , Viscosidade , Água/química , Ácido Ascórbico/química , Ácido Ascórbico/farmacologia
5.
Bioorg Chem ; 147: 107402, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38688199

RESUMO

A series of novel l-ascorbic acid derivatives bearing aryl and alkyl sulfonate substituents were synthesized and characterized. In vitro anticancer evaluation against MCF-7 (breast) and A-549 (lung) cancer cell lines revealed potent activity for most of the compounds, with 2b being equipotent to the standard drug colchicine against MCF-7 (IC50 = 0.04 µM). Notably, compound 2b displayed 89-fold selectivity for MCF-7 breast cancer over MCF-10A normal breast cells. Derivatives with two sulfonate groups (2a-g, 3a-g) exhibited superior potency over those with one sulfonate (4a-c,5g, 6b). Compounds 2b and 2c potently inhibited tubulin polymerization in A-549 cancer cells (73.12 % and 62.09 % inhibition, respectively), substantiating their anticancer potential through microtubule disruption. Molecular docking studies showed higher binding scores and affinities for these compounds at the colchicine-binding site of α, ß-tubulin compared to colchicine itself. In-silico ADMET predictions indicated favourable drug-like properties, with 2b exhibiting the highest binding affinity. These sulfonate derivatives of l-ascorbic acid represents promising lead scaffolds for anticancer drug development.


Assuntos
Antineoplásicos , Ácido Ascórbico , Proliferação de Células , Desenho de Fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Simulação de Acoplamento Molecular , Moduladores de Tubulina , Tubulina (Proteína) , Humanos , Antineoplásicos/farmacologia , Antineoplásicos/química , Antineoplásicos/síntese química , Ácido Ascórbico/química , Ácido Ascórbico/farmacologia , Tubulina (Proteína)/metabolismo , Relação Estrutura-Atividade , Moduladores de Tubulina/farmacologia , Moduladores de Tubulina/síntese química , Moduladores de Tubulina/química , Estrutura Molecular , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Polimerização/efeitos dos fármacos , Ácidos Sulfônicos/química , Ácidos Sulfônicos/antagonistas & inibidores , Ácidos Sulfônicos/farmacologia , Linhagem Celular Tumoral
6.
Molecules ; 29(8)2024 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-38675551

RESUMO

This study aimed to determine the effect of the drying method (freeze-drying, air-drying), storage period (12 months), and storage conditions (2-4 °C, 18-22 °C) applied to two legume species: green beans and green peas. The raw and dried materials were determined for selected physical parameters typical of dried vegetables, contents of bioactive components (vitamin C and E, total chlorophyll, total carotenoids, ß-carotene, and total polyphenols), antioxidative activity against the DPPH radical, and sensory attributes (overall quality and profiles of color, texture, and palatability). Green beans had a significantly higher content of bioactive components compared to peas. Freeze-drying and cold storage conditions facilitated better retention of these compounds, i.e., by 9-39% and 3-11%, respectively. After 12 months of storage, higher retention of bioactive components, except for total chlorophyll, was determined in peas regardless of the drying method, i.e., by 38-75% in the freeze-dried product and 30-77% in the air-dried product, compared to the raw material.


Assuntos
Antioxidantes , Clorofila , Fabaceae , Liofilização , Verduras , Antioxidantes/análise , Antioxidantes/química , Verduras/química , Clorofila/análise , Clorofila/química , Fabaceae/química , Carotenoides/análise , Carotenoides/química , Armazenamento de Alimentos/métodos , Polifenóis/análise , Polifenóis/química , Ácido Ascórbico/análise , Ácido Ascórbico/química , Dessecação/métodos , beta Caroteno/análise , beta Caroteno/química , Pisum sativum/química , Compostos Fitoquímicos/análise , Compostos Fitoquímicos/química , Vitamina E/análise , Vitamina E/química
7.
Metallomics ; 16(5)2024 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-38614957

RESUMO

Metal ion-catalyzed overproduction of reactive oxygen species (ROS) is believed to contribute significantly to oxidative stress and be involved in several biological processes, from immune defense to development of diseases. Among the essential metal ions, copper is one of the most efficient catalysts in ROS production in the presence of O2 and a physiological reducing agent such as ascorbate. To control this chemistry, Cu ions are tightly coordinated to biomolecules. Free or loosely bound Cu ions are generally avoided to prevent their toxicity. In the present report, we aim to find stable Cu-ligand complexes (Cu-L) that can efficiently catalyze the production of ROS in the presence of ascorbate under aerobic conditions. Thermodynamic stability would be needed to avoid dissociation in the biological environment, and high ROS catalysis is of interest for applications as antimicrobial or anticancer agents. A series of Cu complexes with the well-known tripodal and tetradentate ligands containing a central amine linked to three pyridyl-alkyl arms of different lengths were investigated. Two of them with mixed arm length showed a higher catalytic activity in the oxidation of ascorbate and subsequent ROS production than Cu salts in buffer, which is an unprecedented result. Despite these high catalytic activities, no increased antimicrobial activity toward Escherichia coli or cytotoxicity against eukaryotic AGS cells in culture related to Cu-L-based ROS production could be observed. The potential reasons for discrepancy between in vitro and in cell data are discussed.


Assuntos
Cobre , Espécies Reativas de Oxigênio , Cobre/metabolismo , Cobre/química , Espécies Reativas de Oxigênio/metabolismo , Ligantes , Catálise , Humanos , Escherichia coli/metabolismo , Escherichia coli/efeitos dos fármacos , Complexos de Coordenação/química , Complexos de Coordenação/metabolismo , Complexos de Coordenação/farmacologia , Ácido Ascórbico/metabolismo , Ácido Ascórbico/química , Oxirredução
8.
Biosens Bioelectron ; 257: 116296, 2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-38643550

RESUMO

Breathing is an important physiological activity of human body, which not only reflects the state of human movement, but also is one of the important health indicators. Breathing can change the concentration of water molecules, so monitoring humidity has gradually become a hot topic in modern research. In this study, a humidity sensing composite film with high sensitivity and short response time was made by using the mixture of graphene oxide (GO) and bacterial cellulose (BC) with simple dry film-forming method. L-ascorbic acid was used as reducing agent to reduce GO and improve the conductivity of GO/BC composite film (BG). The influence of different BC contents and the different reduction degree on the resistance change rate of composite film was investigated in details. The maximum resistance change rate of partially reduced BG humidity sensitive composite film reached up to 94%, and the response and recovery time were 13 s and 47 s respectively. Furthermore, the sensor shows obvious resistance change in noncontact sensing test and different breathing states. This kind of humidity sensitive film with fast response and high sensitivity has great potential in human health monitoring and noncontact sensing, and is of great significance in promoting health detection and intelligent life.


Assuntos
Técnicas Biossensoriais , Celulose , Grafite , Umidade , Grafite/química , Celulose/química , Humanos , Técnicas Biossensoriais/instrumentação , Bactérias/isolamento & purificação , Ácido Ascórbico/química , Ácido Ascórbico/análise
9.
Food Chem ; 448: 139073, 2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-38574713

RESUMO

This study reported for the first time that Ascorbic acid (AA) could appreciably boost the efficiency of Octyl gallate (OG)-mediated photodynamic inactivation (PDI) on Escherichia coli and Staphylococcus aureus in planktonic and biofilm states. The combination of OG (0.075 mM) and AA (200 mM) with 420 nm blue light (212 mW/cm2) led to a >6 Log killing within only 5 min for E. coli and S. aureus and rapid eradication of biofilms. The mechanism of action appears to be the generation of highly toxic hydroxyl radicals (•OH) via photochemical pathways. OG was exposed to BL irradiation to generate various reactive oxygen radicals (ROS) and the addition of AA could transform singlet oxygen (1O2) into hydrogen peroxide (H2O2), which could further react with AA to generate enormous •OH. These ROS jeopardized bacteria and biofilms by nonspecifically attacking various biomacromolecules. Overall, this PDI strategy provides a powerful microbiological decontamination modality to guarantee safe food products.


Assuntos
Ácido Ascórbico , Biofilmes , Escherichia coli , Ácido Gálico , Ácido Gálico/análogos & derivados , Luz , Staphylococcus aureus , Biofilmes/efeitos dos fármacos , Ácido Ascórbico/farmacologia , Ácido Ascórbico/química , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/fisiologia , Ácido Gálico/farmacologia , Ácido Gálico/química , Escherichia coli/efeitos dos fármacos , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/química , Antibacterianos/farmacologia , Antibacterianos/química , Viabilidade Microbiana/efeitos dos fármacos , Viabilidade Microbiana/efeitos da radiação , Espécies Reativas de Oxigênio/metabolismo , Plâncton/efeitos dos fármacos , Plâncton/efeitos da radiação , Luz Azul
10.
Ultrason Sonochem ; 105: 106868, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38581798

RESUMO

The use of extracts rich in bioactive compounds is becoming increasingly common in the food, cosmetics, and pharmaceutical industries for the production of functional products. Araticum is a potential fruit to be analyzed due to its content of phenolic compounds, carotenoids and vitamins, with antioxidant properties. Therefore, this study aimed to investigate the effect of ultrasound on total phenolic compounds, total carotenoids, ascorbic acid, color, turbidity and rheology in araticum juice. Response surface methodology based on a central composite design was applied. Araticum juice was subjected to sonication at amplitude levels ranging from 20 to 100 % of the total power (400 W) at a constant frequency of 20 kHz for different durations (2 to 10 min). Morphological analysis was conducted to observe microscopic particles, and viscosity and suitability to rheological models (Newtonian, Power Law, and Herschel-Bulkley) were assessed. The ultrasonic probe extraction method was compared to the control juice. According to the responses, using the desirability function, the optimal conditions for extraction were determined to be low power (low amplitude) applied in a short period of time or low power applied in a prolonged time. These conditions allowed an ultrasonic probe to act on releasing bioactive compounds without degrading them. All three rheological models were suitable, with the Power Law model being the most appropriate, exhibiting non-Newtonian pseudoplastic behavior.


Assuntos
Reologia , Annona/química , Sucos de Frutas e Vegetais/análise , Carotenoides/química , Viscosidade , Ondas Ultrassônicas , Sonicação , Fenóis/química , Ácido Ascórbico/química
11.
Appl Spectrosc ; 78(6): 633-643, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38529537

RESUMO

The precise regulation of nanoenzyme activity is of great significance for application to biosensing analysis. Herein, the peroxidase-like activity of carbon dots was effectively modulated by doping phosphorus, which was successfully employed for sensitive, selective detection of acid phosphatase (ACP). Phosphorus-doped carbon dots (P-CDs) with excellent peroxidase-like activity were synthesized by a one-pot hydrothermal method, and the catalytic activity could be easily modulated by controlling the additional amount of precursor phytic acid. P-CDs could effectively catalyze the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue TMB oxidation products in the presence of hydrogen peroxide. While ACP was able to catalyze the hydrolysis of L-ascorbyl-2-phosphate trisodium salt (AAP) to produce ascorbic acid (AA), which inhibited the peroxidase-like activity of P-CDs, by combining P-CDs nanoenzymes and ACP-catalyzed hydrolysis the colorimetric method was established for ACP detection. The absorbance variation showed a good linear relationship with ACP concentration in the range of 0.4-4.0 mU/mL with a limit of detection at 0.12 mU/mL. In addition, the method was successfully applied to detect ACP in human serum samples with recoveries in the range of 98.7-101.6%. The work provides an effective strategy for regulating nanoenzymes activity and a low-cost detection technique for ACP.


Assuntos
Fosfatase Ácida , Carbono , Colorimetria , Limite de Detecção , Fósforo , Pontos Quânticos , Colorimetria/métodos , Carbono/química , Pontos Quânticos/química , Humanos , Fosfatase Ácida/análise , Fosfatase Ácida/sangue , Fosfatase Ácida/química , Fósforo/química , Benzidinas/química , Peroxidase/química , Peroxidase/metabolismo , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/análise , Oxirredução , Ácido Ascórbico/análise , Ácido Ascórbico/química , Ácido Ascórbico/sangue , Ácido Ascórbico/análogos & derivados
12.
Chem Biodivers ; 21(5): e202400315, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38484117

RESUMO

Pineapple (Ananas comosus), the succulent and vibrant tropical fruit, is a symbol of exoticism and sweetness that captures the hearts and palates of people around the world. The pineapple peel, often considered as waste, has garnered attention for its potential applications. The pineapple peel is rich in essential nutrients, including calcium, potassium, vitamin C, carbohydrates, dietary fiber, and water, making it beneficial for the digestive system, weight management, and overall balanced nutrition. It contains significant amounts of sugars such as sucrose, glucose, and fructose, along with citric acid as the predominant organic acid. The peel also contains bromelain, a proteolytic enzyme known for its digestive properties. Studies have highlighted the pharmacological properties of pineapple peel, such as its potential anti-parasitic effects, alleviation of constipation, and benefits for individuals with irritable bowel syndrome (IBS). Efforts are being made to promote the utilization of pineapple peel as a valuable resource rather than mere waste. Its applications range from the production of vinegar, alcohol, and citric acid to the development of various food products, including squash, syrup, jelly, and pickles. Further research and innovation are required to fully explore the potential of pineapple peel and establish sustainable practices for its utilization, contributing to waste reduction and the development of value-added products.


Assuntos
Ananas , Humanos , Ananas/química , Frutas/química , Valor Nutritivo , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Ácido Ascórbico/química , Potássio/química , Carboidratos/química
13.
Int J Biol Macromol ; 266(Pt 1): 131021, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38522689

RESUMO

κ-Carrageenan (KC) is a polysaccharide widely used in food industry. It has been widely studied for its excellent physicochemical and beneficial properties. However, the high molecular weight and high viscosity of KC make it difficult to be absorbed and to exert its' biological activities, thus limit its extensive industrial application. In order to solve this problem, five low molecular weight κ-carrageenans (DCPs) were prepared by the degradation of KC using hydrogen peroxide (H2O2) and ascorbic acid (AH2). The chemical compositions and structure characteristics of the DCPs were then determined. The results showed that H2O2 and AH2 could effectively degrade KC to DCPs, and DCPs remained the basic skeletal structure of KC. DCPs showed good antibacterial activities against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis. The Minimum Inhibitory Concentration (MIC) of DCPs with the highest antibacterial effects were 5.25, 4.5, 5.25, and 4.5 mg/mL, respectively. This is due to the underlying mechanism of DCPs that bind to the bacterial membrane proteins and change the membrane permeability, thus exerting antibacterial activity. In addition, Spearman's rank correlation and Ridge regression analysis revealed that the molecular weight and the contents of 3,6-anhydro-D-galactose, aldehyde group, carboxyl, and sulfate were the main structural characteristics affecting the antibacterial activity. Our findings reveal that the H2O2-AH2 degradation treatment could significantly improve the antibacterial activity of KC and provide insights into the quantitative structure-activity relationships of the antibacterial activity of DCPs.


Assuntos
Antibacterianos , Carragenina , Peso Molecular , Antibacterianos/farmacologia , Antibacterianos/química , Carragenina/química , Carragenina/farmacologia , Relação Estrutura-Atividade , Testes de Sensibilidade Microbiana , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/farmacologia , Escherichia coli/efeitos dos fármacos , Ácido Ascórbico/química , Ácido Ascórbico/farmacologia , Staphylococcus aureus/efeitos dos fármacos
14.
Dalton Trans ; 53(14): 6275-6281, 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38506644

RESUMO

The detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA) is not only of great significance in the areas of biomedicine and neurochemistry but also helpful in disease diagnosis and pathology research. Due to their diverse structures, designability, and large specific surface areas, metal-organic frameworks (MOFs) have recently caught considerable attention in the electrochemical field. Herein, a family of heterometallic MOFs with amino modification, MIL-125(Ti-Al)-xNH2 (x = 0%, 25%, 50%, 75%, and 100%), were synthesized and employed as electrochemical sensors for the detection of AA, DA, and UA. Among them, MIL-125(Ti-Al)-75%NH2 exhibited the most promising electrochemical behavior with 40% doping of carbon black in 0.1 M PBS (pH = 7.10), which displayed individual detection performance with wide linear detection ranges (1.0-6.5 mM for AA, 5-100 µM for DA and 5-120 µM for UA) and low limits of detection (0.215 mM for AA, 0.086 µM for DA, and 0.876 µM for UA, S/N = 3). Furthermore, the as-prepared MIL-125(Ti-Al)-75%NH2/GCE provided a promising platform for future application in real sample analysis, owing to its excellent anti-interference performance and good stability.


Assuntos
Dopamina , Estruturas Metalorgânicas , Dopamina/análise , Ácido Úrico/análise , Ácido Ascórbico/química , Eletrodos , Titânio , Técnicas Eletroquímicas
15.
J Colloid Interface Sci ; 661: 1060-1069, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38335790

RESUMO

Herein, a novel dual-mode probe for organophosphorus pesticides (OPs) colorimetric and photothermal detection was developed based on manganese modified porphyrin metal-organic framework (PCN-224-Mn). PCN-224-Mn had excellent oxidase-like activity and oxidized colorless 3,3,5,5-tetramethylbenzidine (TMB) to blue-green oxidation state TMB (oxTMB), which exhibited high temperature under near-infrared irradiation. l-ascorbate-2-phosphate was hydrolyzed by acid phosphatase to produce ascorbic acid, which weakened colorimetric and photothermal signals by impacting oxTMB generation. The presence of OPs blocked the production of ascorbic acid by irreversibly inhibiting the activity of acid phosphatase, causing the restoration of chromogenic reaction and the increase of temperature. Under the optimal conditions, the probe showed a good linear response to OPs in the concentration range of 5 âˆ¼ 10000 ng/mL, using glyphosate as the analog. The detection limits of glyphosate in colorimetric mode and photothermal mode were 1.47 ng/mL and 2.00 ng/mL, respectively. The probe was successfully used for sensitive identification of OPs residues in tea, brown rice, and wheat flour. This work proposes a simple and reliable colorimetric/photothermal platform for OPs identification, which overcomes the problem that single-mode detection probes are susceptible to external factors, and has broad application potential in the field of food safety.


Assuntos
Benzidinas , Estruturas Metalorgânicas , Praguicidas , Compostos Organofosforados , Colorimetria , Farinha , Triticum , Ácido Ascórbico/química , Fosfatase Ácida
16.
Spectrochim Acta A Mol Biomol Spectrosc ; 309: 123813, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38198998

RESUMO

Ascorbic acid (AH2) photoxidation sensitized by riboflavin (RF) has been studied between pH 2.0 and 12.0 in ambient air and anaerobic environment using UV and visible irradiation sources. The kinetics of AH2 degradation in aqueous medium along with RF is found to be first-order for its photodegradation. AH2 photolysis rate constants in aerobic and anaerobic conditions with RF (1.0-5.0 × 10-5 M) are 0.14-3.89 × 10-2 and 0.026-0.740 × 10-2 min-1, respectively. The rate constants (k2) of second-order kinetics for AH2 and RF photochemical interaction in aerobic and anaerobic conditions are in the range of 0.24-3.70 to 0.05-0.70 × 10-3 M-1 min-1, respectively, which manifests that increasing the RF concentration also increases the rate of photodegradation (photooxidation) of AH2. The k2 versus pH graph is bell-shaped which indicates that increasing the pH increases photolytic degradation rate of AH2 with RF. Increasing the pH results in the increased ionization of AH2 (ascorbyl anion, AH-) and redox potential which leads to the higher rates of photodegradation of AH2. Two-component spectrophotometric (243 and 266 nm, AH2 and RF, respectively) and high-performance liquid chromatography (HPLC) methods have been used to determine the concentration of AH2 and RF in pure and degraded solutions. The results obtained from these two methods are compared using a student t-test which showed no noteworthy difference between them.


Assuntos
Ácido Ascórbico , Riboflavina , Riboflavina/química , Ácido Ascórbico/química , Vitaminas , Fotólise , Luz , Cinética
17.
Electrophoresis ; 45(7-8): 639-650, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38227365

RESUMO

In this work, we proposed a double moving redox boundary (MROB) model to realize the colorless analyte electrophoresis titration (ET) by the two steps of the redox reaction. Single MROB has been proposed for the development of ET sensing (Analyst, 2013, 138, 1137. ACS Sensor, 2019, 4, 126.), and faces great challenges in detecting the analyte without color change during redox reaction. Herein, a novel model of double-MROB electrophoresis, including its mechanisms, equations, and procedures, was developed for titration by using ascorbic acid as a model analyte. The first MROB was created with ferric iron (Fe3+) and iodide ion (I-) in which Fe3+ was reduced as Fe2+ and I- was oxidized as molecular iodine (I2) used as an indicator of visible MROB due to blue starch-iodine complex. The second boundary was then formed between the molecular iodine and model analyte of ascorbic acid. Under given conditions, there was a quantitative relationship between velocity of MROB (VMROB(ii)) and ascorbic acid concentration (CVit C) in the double-MROB system (1/VMROB(ii) = 0.6502CVit C + 4.5165, and R = 0.9939). The relevant relative standard deviation values of intraday and inter-day were less than ∼5.55% and ∼6.64%, respectively. Finally, the titration of ascorbic acid in chewable vitamin C tablets was performed by the developed method, the titration results agreed with those via the classic iodometric titration. All the results briefly demonstrated the validity of the double MROB model, in which Vit C was used as a model analyte. The developed method had potential use in quantitative analysis of redox-active species in biomedical samples.


Assuntos
Ácido Ascórbico , Oxirredução , Ácido Ascórbico/análise , Ácido Ascórbico/química , Limite de Detecção , Reprodutibilidade dos Testes , Modelos Químicos , Iodo/química , Iodo/análise , Modelos Lineares , Eletroforese/métodos
18.
Eur J Prosthodont Restor Dent ; 32(1): 28-44, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-37463022

RESUMO

INTRODUCTION: This systematic review examined the effect of neutralizing agents on bond strength after irrigation with sodium hypochlorite and their existing protocols in literature. METHODS: This present study adhered to the PRISMA guidelines and was registered at PROSPERO. Five electronic databases were searched (sept-2020/jan-2021) in English, Spanish, and Portuguese, without any restrictions on publication date. Cases reports, editorials and literature reviews were not included. The risk of bias was assessed using the Cochrane Collaboration tool. From the initial 7,147 studies, 2,745 were removed as duplicates and 4,382 were excluded after a title/abstract screen. RESULTS: Seventeen in vitro studies were included. The results showed that the higher the concentration of sodium hypochlorite, the lower the bond strength at dentine/restoration interface (p⟨0.01). Among the studies, sodium ascorbate was the most widely used neutralizer and showed the most significant results in increasing bond strength (p⟨0.01). The bond strength values were found to increase with longer application time of the neutralizing substances (p⟨0.01). CONCLUSIONS: The use of sodium ascorbate as a neutralizing agent can reverse the negative effects of the sodium hypochlorite and improve the bond strength between dentine and resin cement, however, it isn't possible to determine the best protocol for use.


Assuntos
Colagem Dentária , Hipoclorito de Sódio/química , Hipoclorito de Sódio/farmacologia , Cimentos de Resina/química , Ácido Ascórbico/química , Ácido Ascórbico/farmacologia , Dentina , Teste de Materiais
19.
Anal Sci ; 40(2): 301-308, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37971693

RESUMO

Here, screen-printed carbon electrodes (SPCEs) were modified with ultrafine and mainly mono-disperse sea urchin-like tungsten oxide (SUWO3) nanostructures synthesized by a simple one-pot hydrothermal method for non-enzymatic detection of dopamine (DA) and uric acid (UA) in synthetic urine. Sea urchin-like nanostructures were clearly observed in scanning electron microscope images and WO3 composition was confirmed with XRD, Raman, FTIR and UV-Vis spectrophotometer. Modification of SPCEs with SUWO3 nanostructures via the drop-casting method clearly reduced the Rct value of the electrodes, lowered the ∆Ep and enhanced the DA oxidation current due to high electrocatalytic activity. As a result, SUWO3/SPCEs enabled highly sensitive non-enzymatic detection of DA (LOD: 51.4 nM and sensitivity: 127 µA mM-1 cm-2) and UA (LOD: 253 nM and sensitivity: 55.9 µA mM-1 cm-2) at low concentration. Lastly, SUWO3/SPCEs were tested with synthetic urine, in which acceptable recoveries for both molecules (94.02-105.8%) were obtained. Given the high selectivity, the sensor has the potential to be used for highly sensitive simultaneous detection of DA and UA in real biological samples.


Assuntos
Dopamina , Nanoestruturas , Óxidos , Tungstênio , Dopamina/química , Ácido Úrico , Nanoestruturas/química , Eletrodos , Carbono/química , Técnicas Eletroquímicas/métodos , Ácido Ascórbico/química
20.
Ultrason Sonochem ; 102: 106743, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38150956

RESUMO

The impact of intermediate frequency ultrasound (IFUS, 582, 864 and 1144 kHz), mode of operation (continue and pulsed) and ascorbic acid (Aa) addition on the structural, chemical and technofunctional properties of commercial citrus high methoxyl-grade pectin (HMP) was investigated. The chemical dosimetry of IFUS, monitored by the triiodide formation rate (I3-), demonstrated that the pulsed ratio (1900 ms on/100 ms off) at the three frequencies was similar to that of continue mode but IFUS1144 kHz produced more acoustic streaming demonstrated by the height liquid measured using image analysis. In presence of Aa, HMP presented higher fragmentation than in its absence. IFUS did not give rise any changes in the main functional groups of the HMP. In general, a reduction in molecular weight was observed, being the presence of Aa the most influencing factor. Regarding monosaccharides, IFUS modified the structure of homogalacturonan and rhamnogalacturonan-I and increased of GalA contents of the HMP in presence of Aa at the above three frequencies. A reducing of the consistency index (k) and increasing of the flow index (n) of HMP were showed by IFUS frequency and Aa addition. The emulsifying activity and stability index were increased for HMP treated by IFUS in continue mode at all frequencies and in presence of Aa. The results presented in this research shown the effectiveness of IFUS as tool to modify pectin into different structures with different functionalities.


Assuntos
Ácido Ascórbico , Pectinas , Pectinas/química , Peso Molecular , Ácido Ascórbico/química , Monossacarídeos
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