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1.
Int J Mol Sci ; 22(10)2021 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-34068879

RESUMO

The redox chemistry of copper(II) is strongly modulated by the coordination to amyloid-ß peptides and by the stability of the resulting complexes. Amino-terminal copper and nickel binding motifs (ATCUN) identified in truncated Aß sequences starting with Phe4 show very high affinity for copper(II) ions. Herein, we study the oxidase activity of [Cu-Aß4-x] and [Cu-Aß1-x] complexes toward dopamine and other catechols. The results show that the CuII-ATCUN site is not redox-inert; the reduction of the metal is induced by coordination of catechol to the metal and occurs through an inner sphere reaction. The generation of a ternary [CuII-Aß-catechol] species determines the efficiency of the oxidation, although the reaction rate is ruled by reoxidation of the CuI complex. In addition to the N-terminal coordination site, the two vicinal histidines, His13 and His14, provide a second Cu-binding motif. Catechol oxidation studies together with structural insight from the mixed dinuclear complexes Ni/Cu-Aß4-x reveal that the His-tandem is able to bind CuII ions independently of the ATCUN site, but the N-terminal metal complexation reduces the conformational mobility of the peptide chain, preventing the binding and oxidative reactivity toward catechol of CuII bound to the secondary site.


Assuntos
Peptídeos beta-Amiloides/metabolismo , Complexos de Coordenação/metabolismo , Cobre/metabolismo , Dopamina/metabolismo , Oxirredutases/metabolismo , Peptídeos beta-Amiloides/química , Complexos de Coordenação/química , Cobre/química , Dopamina/química , Histidina/química , Histidina/metabolismo , Modelos Moleculares , Conformação Molecular , Oxirredução , Oxirredutases/química
2.
Molecules ; 26(5)2021 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-33806346

RESUMO

Dopamine is a small versatile molecule used for various biotechnological and biomedical applications. This neurotransmitter, in addition to its biological role, can undergo oxidative self-polymerization to yield polydopamine, a robust universal coating material. Herein, we harness dopamine self-polymerization to modulate the viscoelastic mechanical properties of peptide-based gels, expanding their ever-growing application potential. By combining rapid peptide assembly with slower dopamine auto-polymerization, a double network gel is formed, where the fibrillar peptide gel network serves as a scaffold for polydopamine deposition, allowing polydopamine to interpenetrate the gel network as well as establishing crosslinks within the matrix. We have shown that triggering the assembly of a lysine-rich peptide gelator in the presence of dopamine can increase the mechanical rigidity of the resultant gel by a factor of 90 in some cases, while retaining the gel's shear thin-recovery behavior. We further investigate how factors such as polymerization time, dopamine concentration and peptide concentration alter the mechanical properties of the resultant gel. The hybrid peptide-dopamine gel systems were characterized using rheological measurements, circular dichroism spectroscopy and transmission electron microscopy. Overall, triggering peptide gelation in the presence of dopamine represents a simple yet powerful approach to modulate the viscoelastic mechanical properties of peptide-based gels.


Assuntos
Dopamina/química , Géis/química , Fragmentos de Peptídeos/química , Polímeros/química , Substâncias Viscoelásticas/química , Fenômenos Mecânicos , Polimerização , Reologia
3.
Food Chem ; 353: 129464, 2021 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-33740511

RESUMO

The magnetic molecular imprinting polymers nanoparticles (MMIPs NPs) for the extraction of norfloxacin (NOR) were prepared by self-polymerization of dopamine onto the surface of (3-Aminopropyl)triethoxysilane (APTES)-modified Fe3O4 NPs. The MMIPs NPs were characterized by FT-IR spectroscopy, XRD, VSM and TEM. The characterization results show that the MMIPs NPs possess superparamagnetic characteristic with the saturated magnetization value of 38.6 emu/g, and the average particle size of about 14.3 nm. Furthermore, the adsorption performance of the MMIPs NPs was evaluated by the static, dynamic, selective adsorption and reusability experiments. The adsorption capacity of MMINs NPs for NOR is 14.2 mg/g with an imprinted factor of 2.1. About 82.4-102.4% of the added NOR (20, 40, 60 µg/mL) were recovered from fortified milk samples with MMIPs NPs as sorbent. Moreover, the MMIPs NPs can be reused for at least six times.


Assuntos
Leite/química , Impressão Molecular/métodos , Nanopartículas/química , Norfloxacino/isolamento & purificação , Adsorção , Animais , Dopamina/química , Contaminação de Alimentos , Nanopartículas Magnéticas de Óxido de Ferro/química , Fenômenos Magnéticos , Microscopia Eletrônica de Transmissão , Polimerização , Polímeros/química , Espectroscopia de Infravermelho com Transformada de Fourier
4.
Artigo em Inglês | MEDLINE | ID: mdl-33621797

RESUMO

In this work, cellulose filter paper (CFP), which is inexpensive and commercially available, was used as the carrier, and the immobilized α-glucosidase was obtained by two steps: firstly, the surface of CFP was modified by polydopamine/polyethyleneimine (PDA/PEI) co-deposition method to obtain CFP-PDA/PEI with a uniform coating of rich positive charge; subsequently, α-glucosidase was immobilized on the CFP-PDA/PEI by electrostatic adsorption. The free enzyme and immobilized enzyme have the same optimal temperature (70℃) and pH (8.0), and their Km is similar, which is 2.2 and 2.8, respectively. These results show that the immobilization process does not change the properties of the enzyme greatly. The immobilized enzyme still maintains 75.6% of its initial activity after 10 repeated uses, showing good reusability. The excellent repeatability (RSD = 2.2%, n = 5) and the verification of competitive inhibitor (acarbose) illustrates the reliability of the immobilized enzymes for enzyme inhibitor screening. Finally, combined with CE, a screening method based immobilized α-glucosidase was proposed and applied to screen the α-glucosidase inhibitory from 10 kinds of Traditional Chinese medicines (TCMs) in vitro. The results indicated that the method was a very effective tool for screening potential α-glucosidase inhibitors from TCMs.


Assuntos
Celulose/análogos & derivados , Dopamina/química , Enzimas Imobilizadas/metabolismo , Inibidores de Glicosídeo Hidrolases , Polietilenoimina/análogos & derivados , alfa-Glucosidases/metabolismo , Celulose/química , Medicamentos de Ervas Chinesas/análise , Medicamentos de Ervas Chinesas/metabolismo , Eletroforese Capilar , Enzimas Imobilizadas/química , Inibidores de Glicosídeo Hidrolases/análise , Inibidores de Glicosídeo Hidrolases/metabolismo , Concentração de Íons de Hidrogênio , Papel , Polietilenoimina/química , Temperatura , alfa-Glucosidases/química
5.
Nat Commun ; 12(1): 926, 2021 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-33568652

RESUMO

The endocannabinoid system is a promising target to mitigate pain as the endocannabinoids are endogenous ligands of the pain-mediating receptors-cannabinoid receptors 1 and 2 (CB1 and CB2) and TRPV1. Herein, we report on a class of lipids formed by the epoxidation of N-arachidonoyl-dopamine (NADA) and N-arachidonoyl-serotonin (NA5HT) by epoxygenases. EpoNADA and epoNA5HT are dual-functional rheostat modulators of the endocannabinoid-TRPV1 axis. EpoNADA and epoNA5HT are stronger modulators of TRPV1 than either NADA or NA5HT, and epoNA5HT displays a significantly stronger inhibition on TRPV1-mediated responses in primary afferent neurons. Moreover, epoNA5HT is a full CB1 agonist. These epoxides reduce the pro-inflammatory biomarkers IL-6, IL-1ß, TNF-α and nitrous oxide and raise anti-inflammatory IL-10 cytokine in activated microglial cells. The epoxides are spontaneously generated by activated microglia cells and their formation is potentiated in the presence of anandamide. Detailed kinetics and molecular dynamics simulation studies provide evidence for this potentiation using the epoxygenase human CYP2J2. Taken together, inflammation leads to an increase in the metabolism of NADA, NA5HT and other eCBs by epoxygenases to form the corresponding epoxides. The epoxide metabolites are bioactive lipids that are potent, multi-faceted molecules, capable of influencing the activity of CB1, CB2 and TRPV1 receptors.


Assuntos
Anti-Inflamatórios/administração & dosagem , Dopamina/administração & dosagem , Dor/tratamento farmacológico , Receptor CB1 de Canabinoide/imunologia , Receptor CB2 de Canabinoide/imunologia , Serotonina/administração & dosagem , Animais , Anti-Inflamatórios/química , Dopamina/química , Endocanabinoides/administração & dosagem , Endocanabinoides/química , Compostos de Epóxi/química , Feminino , Humanos , Interleucina-10/genética , Interleucina-10/imunologia , Interleucina-1beta/genética , Interleucina-1beta/imunologia , Interleucina-6/genética , Interleucina-6/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Óxido Nitroso/imunologia , Dor/genética , Dor/imunologia , Receptor CB1 de Canabinoide/genética , Receptor CB2 de Canabinoide/genética , Serotonina/química , Canais de Cátion TRPV/genética , Canais de Cátion TRPV/imunologia
6.
Carbohydr Polym ; 255: 117479, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33436241

RESUMO

The research in eco-friendly and sustainable materials for packaging applications with enhanced barrier, thermo-mechanical, rheological and anti-bacterial properties has accelerated in the last decade. Last decade has witnessed immense interest in employing nanocellulose (NC) as a sustainable and biodegradable alternative to the current synthetic packaging barrier films. This review article gathers the research information on NC as a choice for food packaging material. It reviews on the employment of NC and its various forms including its chemico-physical treatments into bio/polymers and its impact on the performance of nanocomposites for food packaging application. The review reveals the fact that the research trends towards NC based materials are quite promising for Active Packaging (AP) applications, including the Controlled Release Packaging (CRP) and Responsive Packaging (RP). Finally, it summarizes with the challenges of sustainable packaging, gray areas that need an improvement/focus in order to commercially exploit this wonderful material for packaging application.


Assuntos
Antibacterianos/química , Celulose/química , Preparações de Ação Retardada/química , Embalagem de Alimentos/métodos , Nanocompostos/química , Resinas Acrílicas/química , Antibacterianos/farmacologia , Biodegradação Ambiental , Celulose/ultraestrutura , Quitosana/química , Preparações de Ação Retardada/farmacologia , Dopamina/química , Humanos , Membranas Artificiais , Poliésteres/química , Vapor/análise , Taninos/química
7.
Carbohydr Polym ; 256: 117511, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33483032

RESUMO

A combined enzymatic treatment/acid hydrolysis technique was utilized to synthesize cellulose nanocrystals (CNCs) from sugar beet pulp. CNCs were functionalized with magnetite nanoparticles and dopamine making a versatile nano-carrier (DA/Fe3O4NPs@CNCs) for covalent enzyme immobilization. Oxygene/amine functionalities, high magnetization value, and specific surface area of DA/Fe3O4NPs@CNCs made it a reusable and green candidate for conjugation to hydrolytic enzyme cocktails (three cellulases, two hemicellulases, and their combinations) to prepare an innovative and practical nano-biocatalyst for biomass conversion. The conjugated enzymes showed an enhanced optimum temperature (∼ 10 °C), improved thermal stability, and shifted optimum pH toward alkaline pHs. Covalent attachment could successfully suppress the enzyme leaching and provide easy recovery/reuse of the nano-biocatalyst up to 10 cycles, with > 50% of initial activity. Application of the nano-biocatalyst in hydrolysis of rice straw and sugar beet pulp showed an increase (20-76%) in the yield of fermentable sugars compared to the free enzyme cocktails.


Assuntos
Celulose/química , Dopamina/química , Enzimas Imobilizadas/química , Nanopartículas de Magnetita/química , Nanotecnologia/métodos , Açúcares/química , Beta vulgaris/química , Biomassa , Estabilidade Enzimática , Fermentação , Humanos , Concentração de Íons de Hidrogênio , Cinética , Nanopartículas de Magnetita/ultraestrutura , Nanopartículas/química , Nanopartículas/ultraestrutura , Raízes de Plantas/química , Temperatura
8.
ACS Appl Mater Interfaces ; 13(3): 3591-3604, 2021 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-33438397

RESUMO

A reversible switchable on-demand UV-triggered drug delivery system (DDS) based on interpenetrating polymer networks (IPNs) with silicone as the host polymer and spiropyran (SP)-functionalized guest polymer is designed and demonstrated. The photo-responsive IPNs provide a new triggered drug delivery concept as they exploit the change in intermolecular interactions (work of adhesion) among the drug, matrix, and solvent when the incorporated hydrophobic SP moieties transform into the hydrophilic merocyanine form upon light irradiation without degradation and disruption of the DDS. The change in how the copolymer composition (hydrophilicity and content) and the lipophilicity of the drug (log P) affect the release profile was investigated. A thermodynamic model, based on Hansen solubility parameters, was developed to design and optimize the polymer composition of the IPNs to obtain the most efficient light-triggered drug release and suppression of the premature release. The developed IPNs showed excellent result for dopamine, l-dopa, and prednisone with around 90-95% light-triggered release. The model was applied to study the release behavior of drugs with different log P and to estimate if the light-induced hydrophobic-to-hydrophilic switch can overcome the work of adhesion between polymers and drugs and hence the desorption and release of the drugs. To the best of our knowledge, this is the first time that work of adhesion is used for this aim. Comparing the result obtained from the model and experiment shows that the model is useful for evaluating and estimating the release behavior of specific drugs merocyanine, IPN, DDS, and spiropyran.


Assuntos
Benzopiranos/química , Preparações de Ação Retardada/química , Indóis/química , Nitrocompostos/química , Polímeros/química , Anti-Inflamatórios/administração & dosagem , Anti-Inflamatórios/química , Dopamina/administração & dosagem , Dopamina/química , Dopaminérgicos/administração & dosagem , Dopaminérgicos/química , Sistemas de Liberação de Medicamentos/métodos , Liberação Controlada de Fármacos/efeitos da radiação , Interações Hidrofóbicas e Hidrofílicas , Levodopa/administração & dosagem , Levodopa/química , Prednisona/administração & dosagem , Prednisona/química , Raios Ultravioleta
9.
Biochimie ; 183: 126-132, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33309753

RESUMO

Tyrosine hydroxylase (TH) catalyses the (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH4)-dependent conversion of L-tyrosine to L-3,4-dihydroxyphenylalanine (L-Dopa), which is the rate-limiting step in the synthesis of dopamine and other catecholamine neurotransmitters and hormones. Dysfunctional mutant TH causes tyrosine hydroxylase deficiency (THD), characterized by symptoms ranging from mild l-Dopa responsive dystonia to severe neuropathy. THD-associated mutations often present misfolding and a propensity to aggregate, characteristics that can also be manifested by dysregulated wild-type TH. TH - and subsequently dopamine - is also reduced in Parkinson's disease (PD) due to the selective death of dopaminergic neurons. Thus, TH is a target for stabilizing small molecular weight compounds that can function as pharmacological chaperones, restoring enzyme folding and function. In this work we carried out a screening of a compound library with 1280 approved drugs and we identified levalbuterol, a beta2-adrenergic agonist that is broadly used in asthma treatment, as an interesting validated binder of human TH. Levalbuterol stabilized TH with reduced affinity compared to dopamine, the end-product and regulatory feedback inhibitor of TH, but without compromising enzymatic activity. Moreover, levalbuterol also delays the formation of TH aggregates and makes the enzyme less sensitive to dopamine, effects that could contribute to ameliorate disorders related to TH, such as THD and PD.


Assuntos
Dopamina/química , Levalbuterol/química , Agregados Proteicos , Dobramento de Proteína , Tirosina 3-Mono-Oxigenase/química , Distúrbios Distônicos/congênito , Distúrbios Distônicos/enzimologia , Distúrbios Distônicos/genética , Humanos , Tirosina 3-Mono-Oxigenase/genética
10.
Carbohydr Polym ; 254: 117316, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33357879

RESUMO

For conductive hydrogels applied in biosensors, wearable devices and so forth, multifunctionality is an inevitable trend of development to meet various practical requirements and enhance human experience. Herein, inspired by nanocomposite, double-network (DN) and mussel chemistry, a new Graphene oxide@Dopamine/Alginate/Poly(acrylic acid-co-acrylamide) [GO@DA/Alginate/P(AAc-co-AAm)] hydrogel was fabricated through one-pot in-situ radical copolymerization. GO@DA nanofillers, prepared via GO confined DA polymerization, imparted the hydrogel with remarkable adhesiveness. Alginate/P(AAc-co-AAm) DN matrix, physically and chemically crosslinked by Fe3+ and N,N'-Methylenebisacrylamide, made hydrogels ultrastretchable, self-healing and biocompatible. With contents of DA and alginate accurately regulated, the tensile strength, elongation, adhesion strength and conductivity of the optimal hydrogel could reach 320.2 kPa, 1198 %, 36.9 kPa and 3.24 ± 0.12 S/m, respectively. What's more notable was that the synergistic integration of repeatable adhesiveness, strain sensitivity, use stability, self-healing ability and biocompatibility provided such hydrogels with tremendous possibility of practical application for strain sensors.


Assuntos
Acrilamidas/química , Adesivos/química , Alginatos/química , Bivalves/química , Dopamina/química , Grafite/química , Hidrogéis/química , Nanogéis/química , Adesividade , Animais , Materiais Biocompatíveis/química , Técnicas Biossensoriais , Sobrevivência Celular/efeitos dos fármacos , Condutividade Elétrica , Humanos , Camundongos , Células NIH 3T3 , Testes do Emplastro , Polimerização , Resistência à Tração
11.
ACS Appl Mater Interfaces ; 12(52): 57782-57797, 2020 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-33336572

RESUMO

The development of natural polymer-based hydrogels, combining outstanding injectability, self-healing, and tissue adhesion, with mechanical performance, able to facilitate full-thickness skin wound healing, remains challenging. We have developed an injectable micellar hydrogel (AF127/HA-ADH/OHA-Dop) with outstanding adhesive and self-healing properties able to accelerate full-thickness skin wound healing. Dopamine-functionalized oxidized hyaluronic acid (OHA-Dop), adipic acid dihydrazide-modified HA (HA-ADH), and aldehyde-terminated Pluronic F127 (AF127) were employed as polymer backbones. They were cross-linked in situ using Schiff base dynamic covalent bonds (AF127 micelle/HA-ADH network and HA-ADH/OHA-Dop network), hydrogen bonding, and π-π stacking interactions. The resulting multicross-linked double-network design forms a micellar hydrogel. The unique multicross-linked double-network structure endows the hydrogel with both improved injection abilities and mechanical performance while self-healing faster than single-network hydrogels. Inspired by mussel foot adhesive protein, OHA-Dop mimics the catechol groups seen in mussel proteins, endowing hydrogels with robust adhesion properties. We also demonstrate the potential of our hydrogels to accelerate full-thickness cutaneous wound closure and improve skin regeneration with reduced scarring. We anticipate that our hydrogel platform based on a novel multicross-linked double-network design will transform the future development of multifunctional wound dressings.


Assuntos
Hidrogéis/química , Hidrogéis/farmacologia , Fenômenos Fisiológicos da Pele/efeitos dos fármacos , Cicatrização/efeitos dos fármacos , Adesividade , Linhagem Celular , Dopamina/química , Ácido Hialurônico/química , Ligação de Hidrogênio , Injeções , Cinética , Micelas , Modelos Moleculares , Conformação Molecular , Oxirredução
12.
PLoS One ; 15(7): e0235407, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32649670

RESUMO

Fast scan cyclic voltammetry (FSCV) allows for real -time analysis of phasic neurotransmitter levels. Tryptophan (TRP) is an aromatic amino acid responsible for facilitating electron transfer kinetics in oxidoreductase enzymes. Previous work with TRP-modified electrodes showed increased sensitivity for cyclic voltammetry detection of dopamine (DA) when used with slower scan rates (0.05 V/s). Here, we outline an in vitro proof of concept for TRP-modified electrodes in FSCV detection of DA, and decreased sensitivity for ascorbic acid (AA). TRP-modified electrodes had a limit of detection (LOD) for DA of 2.480 ± 0.343 nM compared to 8.348 ± 0.405 nM for an uncoated electrode. Selectivity for DA/ascorbic acid (AA) was 1.107 ± 0.3643 for uncoated and 15.57 ± 4.184 for TRP-modified electrodes. Additionally, these TRP-modified electrodes demonstrated reproducibility when exposed to extended cycling. TRP-modified electrodes will provide an effective modification to increase sensitivity for DA.


Assuntos
Técnicas Biossensoriais , Dopamina/isolamento & purificação , Técnicas Eletroquímicas , Ácido Ascórbico/química , Carbono/química , Dopamina/química , Eletrodos , Cinética , Triptofano/química , Ácido Úrico/química
13.
Nature ; 584(7819): 125-129, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32528175

RESUMO

The D2 dopamine receptor (DRD2) is a therapeutic target for Parkinson's disease1 and antipsychotic drugs2. DRD2 is activated by the endogenous neurotransmitter dopamine and synthetic agonist drugs such as bromocriptine3, leading to stimulation of Gi and inhibition of adenylyl cyclase. Here we used cryo-electron microscopy to elucidate the structure of an agonist-bound activated DRD2-Gi complex reconstituted into a phospholipid membrane. The extracellular ligand-binding site of DRD2 is remodelled in response to agonist binding, with conformational changes in extracellular loop 2, transmembrane domain 5 (TM5), TM6 and TM7, propagating to opening of the intracellular Gi-binding site. The DRD2-Gi structure represents, to our knowledge, the first experimental model of a G-protein-coupled receptor-G-protein complex embedded in a phospholipid bilayer, which serves as a benchmark to validate the interactions seen in previous detergent-bound structures. The structure also reveals interactions that are unique to the membrane-embedded complex, including helix 8 burial in the inner leaflet, ordered lysine and arginine side chains in the membrane interfacial regions, and lipid anchoring of the G protein in the membrane. Our model of the activated DRD2 will help to inform the design of subtype-selective DRD2 ligands for multiple human central nervous system disorders.


Assuntos
Microscopia Crioeletrônica , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/química , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/ultraestrutura , Lipídeos de Membrana/metabolismo , Membranas Artificiais , Receptores de Dopamina D2/química , Receptores de Dopamina D2/ultraestrutura , Bromocriptina/química , Bromocriptina/metabolismo , Dopamina/química , Dopamina/metabolismo , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/metabolismo , Humanos , Lipídeos de Membrana/química , Modelos Moleculares , Conformação Proteica , Receptores de Dopamina D2/agonistas , Receptores de Dopamina D2/metabolismo , Transdução de Sinais
14.
J Surg Res ; 251: 262-274, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32197182

RESUMO

BACKGROUND: Myelomeningocele (MMC) is an open neural tube defect of the spinal column. Our laboratory previously introduced a reverse thermal gel (RTG) as the first in situ forming patch for in utero MMC application. To overcome the challenges of anchoring the RTG in the wet amniotic environment to improve MMC coverage, we modified the RTG to mimic the underwater adhesive properties of mussels. We have separated this study into three separate hypotheses-based components: CONCLUSIONS: The DRTG demonstrates increased elasticity, cellular scaffolding properties, and improved MMC coverage in the Grhl3 mouse model. Future studies will be translated to the preclinical ovine model to evaluate this novel gel.


Assuntos
Dopamina/química , Meningomielocele/terapia , Adesivos Teciduais/uso terapêutico , Ureia/uso terapêutico , Animais , Animais Recém-Nascidos , Bivalves/química , Proteínas de Ligação a DNA/genética , Modelos Animais de Doenças , Feminino , Géis , Masculino , Camundongos , Gravidez , Adesivos Teciduais/química , Fatores de Transcrição/genética , Ureia/análogos & derivados , Ureia/síntese química
15.
Anal Chim Acta ; 1102: 46-52, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-32043995

RESUMO

The electrochemical flow cell containing track-etched microporous membrane electrodes was applied to a dual-electrode coulometric detector for microbore/capillary HPLC with a small injection volume and low eluent flow rate. The proposed flow cell with a 0.1-mm diameter inlet channel gave a detection volume of 0.08 nL per electrode, which was determined by the eluent flow through the electrode. For the dual-electrode detector, the calculated volume was 0.24 nL. The efficiency of electrooxidation of l-ascorbic acid increased as the flow rate decreased and was close to 100% when the flow rate was below 50 µL min-1, which is a common flow rate in microbore or capillary liquid chromatography. Catecholamines, such as noradrenaline, adrenaline, and dopamine, were detected by total conversion with two-electron oxidation in the potential range from 0.8 to 1.0 V vs. Ag/AgCl after separation with a microbore column. These peaks were accompanied by corresponding cathodic peaks derived from quasi-stable electrooxidation products of the catecholamines. The detection limits of noradrenaline, adrenaline, and dopamine were 0.1, 0.1, and 0.2 µM, respectively. The RSD values for five replicate measurements of 5.0 µM of these compounds were 0.9%, 0.7%, and 1.5%, respectively. Coulometric detection was also demonstrated by determination of catecholamines in pharmaceuticals.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Técnicas Eletroquímicas/métodos , Eletrodos , Membranas Artificiais , Ácido Ascórbico/química , Cromatografia Líquida de Alta Pressão/instrumentação , Dopamina/análise , Dopamina/química , Técnicas Eletroquímicas/instrumentação , Epinefrina/análise , Epinefrina/química , Limite de Detecção , Norepinefrina/análise , Norepinefrina/química , Oxirredução
16.
Chem Commun (Camb) ; 56(20): 3065-3068, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-32049076

RESUMO

Herein, a novel stacked hexagonal prism, Ag@Ni-MOF-1, was designed and developed as an integrated SERS platform not only for successfully catalyzing the in situ synthesis of DA-quinone under physiological pH, but also for establishing an approach for specific determination of Cys, an important species in the brain related to Alzheimer's disease (AD).


Assuntos
Benzoquinonas/síntese química , Materiais Biomiméticos/química , Dopamina/síntese química , Níquel/química , Compostos Organometálicos/química , Prata/química , Benzoquinonas/química , Catálise , Cisteína/análise , Dopamina/química , Humanos , Concentração de Íons de Hidrogênio , Compostos Organometálicos/síntese química , Análise Espectral Raman
17.
Nanotechnology ; 31(17): 175501, 2020 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-31914433

RESUMO

A gold nanoparticle-based localized surface plasmon resonance substrate has been developed as nano-sensors for various bio-applications. However, reproducible and robust sensing substrates anchored gold nanoparticles has not yet been explored. In this study, dopamine-coated gold nanorods (DGNRs) were prepared and immobilized onto the micro-grooving PDMS substrates (mgPDMS). Subsequently, HER2-specific aptamers were conjugated with DGNR/mgPDMS for ECD-HER2 detection. By screening of the optimal concentration of DGNR and aptamers, the effective HER2-specific aptasensor was built up. In particular, the real-time binding assay for the evaluation of limit-of-detection (<5 ng ml-1) was conducted. Furthermore, the binding kinetics for ECD-HER2 was investigated under the biological fluid using a rat serum. Our HER2-specific aptasensor demonstrated the effective sensitivity and selectivity for ECD-HER2.


Assuntos
Aptâmeros de Nucleotídeos/química , Dopamina/química , Receptor ErbB-2/análise , Animais , Técnicas Biossensoriais , Ouro , Limite de Detecção , Masculino , Nanopartículas Metálicas , Ratos , Receptor ErbB-2/sangue , Ressonância de Plasmônio de Superfície
18.
ACS Appl Mater Interfaces ; 12(5): 5658-5670, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31986005

RESUMO

Alzheimer's disease (AD) is one of the common causes of dementia and mild cognitive impairments, which is progressively expanding among the elderly population worldwide. A short Amyloid-ß (Aß) peptide generated after amyloidogenic processing of amyloid precursor protein exist as intermolecular ß-sheet rich oligomeric, protofibriler, and fibrillar structures and believe to be toxic species which instigate neuronal pathobiology in the brain and deposits as senile plaque. Enormous efforts are being made to develop an effective anti-AD therapy that can target Aß processing, aggregation, and propagation and provide a synergistic neuroprotective effect. However, a nanodrug prepared from natural origin can confer a multimodal synergistic chemo/photothermal inhibition of Aß pathobiology is not yet demonstrated. In the present work, we report a dopamine-melatonin nanocomposite (DM-NC), which possesses a synergistic near-infrared (NIR) responsive photothermal and pharmacological modality. The noncovalent interaction-mediated self-assembly of melatonin and dopamine oxidative intermediates leads to the evolution of DM-NCs that can withstand variable pH and peroxide environment. NIR-activated melatonin release and photothermal effect collectively inhibit Aß nucleation, self-seeding, and propagation and can also disrupt the preformed Aß fibers examined using in vitro Aß aggregation and Aß-misfolding cyclic amplification assays. The DM-NCs display a higher biocompatibility to neuroblastoma cells, suppress the AD-associated generation of intracellular reactive oxygen species, and are devoid of any negative impact on the axonal growth process. In okadaic acid-induced neuroblastoma and ex vivo midbrain slice culture-based AD model, DM-NCs exposure suppresses the intracellular Aß production, aggregation, and accumulation. Therefore, this nature-derived nanocomposite demonstrates a multimodal NIR-responsive synergistic photothermal and pharmacological modality for effective AD therapy.


Assuntos
Peptídeos beta-Amiloides/química , Dopamina/química , Melatonina/química , Nanocompostos/efeitos da radiação , Neurônios/efeitos dos fármacos , Doença de Alzheimer/metabolismo , Amiloide/efeitos dos fármacos , Amiloide/metabolismo , Peptídeos beta-Amiloides/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Química Encefálica , Linhagem Celular Tumoral , Dopamina/farmacologia , Feminino , Humanos , Raios Infravermelhos , Melatonina/farmacologia , Camundongos , Camundongos Endogâmicos BALB C , Nanocompostos/química , Neuroblastoma , Neurônios/metabolismo , Espécies Reativas de Oxigênio/metabolismo
19.
Biosens Bioelectron ; 151: 111977, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31999583

RESUMO

In this study, titania-ceria-graphene quantum dot (TC-GQD) nanocomposite was synthesized by hydrothermal method for the first time. The prepared nanomaterials were characterized by XRD, FTIR dynamic light scattering (DLS), FESEM, HRTEM, and EDX spectroscopy along with elemental mapping. The synergistic effect of the nanocomposite components was studied by diffuse reflectance spectroscopy (DRS) and electrical conductivity meter. The results showed that band gap of TC-GQD nanocomposite was shifted to visible lights relative to its components (1.3 eV), and electrical conductivity of the sample was significant increased to 89.5 µS cm-1. After chemical and physical characterization, prepared new nanocomposites were used to design a new electrochemical (EC) and photoelectrochemical (PEC) dopamine (DA) sensors. In both EC and PEC methods effecting experimental parameters were optimized. Due to the synergic effect of the nanocomposite components, an outstanding photocurrent response was observed for DA based on PEC sensor. A linear calibration curve with a lower detection limit of 22 nM DA, and sensitivity of 13.8 mA/mM(DA), in a wider range of 0.3-750 µM DA, was obtained for TC-GQD/GCE electrode in PEC. While, the TC-GQD/GCE electrode detected DA in the range of 1-500 µM DA, with two linear calibration curve, detection limit of 0.22 µM DA, and sensitivity of 4.9 mA/mM(DA), in the EC. Observed results from EC and PEC sensors are presented and compared.


Assuntos
Técnicas Biossensoriais , Dopamina/isolamento & purificação , Técnicas Eletroquímicas , Nanocompostos/química , Cério/química , Dopamina/química , Grafite/química , Humanos , Limite de Detecção , Nanopartículas Metálicas/química , Pontos Quânticos/química , Titânio/química
20.
J Chromatogr A ; 1618: 460893, 2020 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-31980263

RESUMO

Seven retention models have been selected to describe a dual-retention behavior of ten dopamine-related compounds on polymer-based monolithic stationary phase with zwitterion sulfobetaine functionality. Regression quality, as well as a statistical significance of individual regression parameters, have been evaluated. Better regression performance showed two four-parameter models when compared to three-parameter models. On the other hand, limited number of experimental points disqualified statistical robustness of four-parameter models. Among three-parameter models, retention description introduced by Horváth and Liang provided comparable quality of regression at significantly improved robustness. Multivariate analysis of the best three-parameter models provided the description of physicochemical properties of dopamine precursors and metabolites. Principal component analysis and logistic regression allowed structural characterization of dopamine-related compounds based solely on regression parameters extracted from an isocratic elution data. Both polarity and type of functional groups has been correctly assigned for 3-methoxytyramine that has not been part of an evaluation study. Among applied dual-retention models, Horváth´s model, initially developed to describe a retention of ionic compounds on nonpolar stationary phases, provided robust regression of experimental data and allowed an extraction of structural characteristics of dopamine-related compounds.


Assuntos
Dopamina/química , Modelos Químicos , Betaína/análogos & derivados , Betaína/química , Dopamina/análogos & derivados , Estrutura Molecular , Polímeros/química
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