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1.
J Control Release ; 318: 145-157, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31830540

RESUMO

Quantum dots offer superior optical features and hold a great potential as an imaging tool in comparison to 'conventional' fluorescent dyes. However, in vivo application in inflammatory-associated disorders is limited due to potential toxicity following systemic administration. Vascular inflammation contributes to cardiovascular diseases such as restenosis (re-narrowing of the artery following angioplasty), and poor prognosis is associated with the increased number of monocytes-derived macrophages (MDMs) in the arterial wall. Local administration of a suitable delivery system targeting MDMs could provide effective fluorescent imaging while minimizing systemic exposure and toxicity. We report here on the physicochemical characteristics and the structural stability of MDMs-targeted liposomal QDs (LipQDs), cellular uptake and cytotoxicity, the systemic biodistribution of LipQDs following local intra-luminal administration of LipQDs in carotid-injured rats vs. systemic administration, and imaging of QDs in the arterial tissue. The local treatment with LipQDs was found to be a suitable approach for targeting QDs to MDMs in the injured artery. In contrast to free QDs, the LipQDs formulation exhibited unique properties including structural and fluorescent stability, increased accumulation and retention for up to 24 h, and targeting properties enabling imaging of MDMs. MDMs imaging by targeted nanoparticles (NPs) could potentially serve for the detection of MDMs density in the injured artery for diagnostic purposes.

2.
Nat Commun ; 10(1): 5401, 2019 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-31844043

RESUMO

Coupling of atoms is the basis of chemistry, yielding the beauty and richness of molecules. We utilize semiconductor nanocrystals as artificial atoms to form nanocrystal molecules that are structurally and electronically coupled. CdSe/CdS core/shell nanocrystals are linked to form dimers which are then fused via constrained oriented attachment. The possible nanocrystal facets in which such fusion takes place are analyzed with atomic resolution revealing the distribution of possible crystal fusion scenarios. Coherent coupling and wave-function hybridization are manifested by a redshift of the band gap, in agreement with quantum mechanical simulations. Single nanoparticle spectroscopy unravels the attributes of coupled nanocrystal dimers related to the unique combination of quantum mechanical tunneling and energy transfer mechanisms. This sets the stage for nanocrystal chemistry to yield a diverse selection of coupled nanocrystal molecules constructed from controlled core/shell nanocrystal building blocks. These are of direct relevance for numerous applications in displays, sensing, biological tagging and emerging quantum technologies.

3.
Nano Lett ; 19(9): 5844-5852, 2019 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-31424944

RESUMO

The majority of developed and approved anticancer nanomedicines have been designed to exploit the dogma of the enhanced permeability and retention (EPR) effect, which is based on the leakiness of the tumor's blood vessels accompanied by impeded lymphatic drainage. However, the EPR effect has been under scrutiny recently because of its variable manifestation across tumor types and animal species and its poor translation to human cancer therapy. To facilitate the EPR effect, systemically injected NPs should overcome the obstacle of rapid recognition and elimination by the mononuclear phagocyte system (MPS). We hypothesized that circulating monocytes, major cells of the MPS that infiltrate the tumor, may serve as an alternative method for achieving increased tumor accumulation of NPs, independent of the EPR effect. We describe here the accumulation of liposomal quantum dots (LipQDs) designed for active delivery via monocytes, in comparison to LipQDs designed for passive delivery (via the EPR effect), following IV administration in a mammary carcinoma model. Hydrophilic QDs were synthesized and entrapped in functionalized liposomes, conferring passive ("stealth" NPs; PEGylated, neutral charge) and active (monocyte-mediated delivery; positively charged) properties by differing in their lipid composition, membrane PEGylation, and charge (positively, negatively, and neutrally charged). The various physicochemical parameters affecting the entrapment yield and optical stability were examined in vitro and in vivo. Biodistribution in the blood, various organs, and in the tumor was determined by the fluorescence intensity and Cd analyses. Following the treatment of animals (intact and mammary-carcinoma-bearing mice) with disparate formulations of LipQDs (differing by their lipid composition, neutrally and positively charged surfaces, and hydrophilic membrane), we demonstrate comparable tumor uptake of QDs delivered by the passive and the active routes (mainly by Ly-6Chi monocytes). Our findings suggest that entrapping QDs in nanosized liposomal formulations, prepared by a new facile method, imparts superior structural and optical stability and a suitable biodistribution profile leading to increased tumor uptake of fluorescently stable QDs.


Assuntos
Lipossomos/farmacologia , Neoplasias Mamárias Animais/tratamento farmacológico , Sistema Fagocitário Mononuclear/química , Pontos Quânticos/química , Animais , Vasos Sanguíneos/efeitos dos fármacos , Linhagem Celular Tumoral , Sistemas de Liberação de Medicamentos , Feminino , Humanos , Interações Hidrofóbicas e Hidrofílicas/efeitos dos fármacos , Lipídeos/química , Lipídeos/farmacologia , Lipossomos/química , Neoplasias Mamárias Animais/patologia , Camundongos , Nanomedicina , Células Neoplásicas Circulantes , Permeabilidade/efeitos dos fármacos
4.
Nanoscale ; 11(23): 11209-11216, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31157812

RESUMO

Semiconductor nanocrystals have been shown to have unique advantages over traditional organic photoinitiators for polymerization in solution. However, efficient photoinitiation with such nanoparticles in solvent-free and additive-free formulations so far has not been achieved. Herein, the ability to use semiconductor nanocrystals for efficient bulk polymerization as sole initiators is reported, operating under modern UV-blue-LED light sources found in 3D printers and other photocuring applications. Hybrid semiconductor-metal nanorods exhibit superior photoinitiation capability to their pristine semiconductor counterparts, attributed to the enhanced charge separation and oxygen consumption in such systems. Moreover, photoinitiation by semiconductor nanocrystals overcoated by inorganic ligands is reported, thus increasing the scope of possible applications and shedding light on the photoinitiation mechanism; in light of the results, two possible pathways are discussed - ligand-mediated and cation-coordinated oxidation. A demonstration of the unique attributes of the quantum photoinitiators is reported in their use for high-resolution two-photon printing of optically fluorescing microstructures, demonstrating a multi-functionality capability. The bulk polymerization demonstrated here can be advantageous over solvent based methods as it alleviates the need of post-polymerization drying and reduces waste and exposure to toxic solvents, as well as broadens the possible use of quantum photoinitiators for industrial and research uses.

5.
Nat Commun ; 10(1): 2, 2019 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-30602734

RESUMO

Semiconductor heterostructure nanocrystals, especially with core/shell architectures, are important for numerous applications. Here we show that by decreasing the shell growth rate the morphology of ZnS shells on ZnSe quantum rods can be tuned from flat to islands-like, which decreases the interfacial strain energy. Further reduced growth speed, approaching the thermodynamic limit, leads to coherent shell growth forming unique helical-shell morphology. This reveals a template-free mechanism for induced chirality at the nanoscale. The helical morphology minimizes the sum of the strain and surface energy and maintains band gap emission due to its coherent core/shell interface without traps, unlike the other morphologies. Reaching the thermodynamic controlled growth regime for colloidal semiconductor core/shell nanocrystals thus offers morphologies with clear impact on their applicative potential.

6.
Adv Mater ; 30(41): e1706697, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29656489

RESUMO

Hybrid semiconductor-metal nanoparticles (HNPs) manifest unique combined and often synergetic properties stemming from the materials combination. These structures exhibit spatial charge separation across the semiconductor-metal junction upon light absorption, enabling their use as photocatalysts. So far, the main impetus of photocatalysis research in HNPs addresses their functionality in solar fuel generation. Recently, it was discovered that HNPs are functional in efficient photocatalytic generation of reactive oxygen species (ROS). This has opened the path for their implementation in diverse biomedical and industrial applications where high spatially temporally resolved ROS formation is essential. Here, the latest studies on the synergistic characteristics of HNPs are summarized, including their optical, electrical, and chemical properties and their photocatalytic function in the field of solar fuel generation is briefly discussed. Recent studies are then focused concerning photocatalytic ROS formation with HNPs under aerobic conditions. The emergent applications of this capacity are then highlighted, including light-induced modulation of enzymatic activity, photodynamic therapy, antifouling, wound healing, and as novel photoinitiators for 3D-printing. The superb photophysical and photocatalytic properties of HNPs offer already clear advantages for their utility in scenarios requiring on-demand light-induced radical formation and the full potential of HNPs in this context is yet to be revealed.


Assuntos
Pontos Quânticos , Animais , Catálise , Humanos , Processos Fotoquímicos , Pontos Quânticos/química
7.
Nano Lett ; 17(7): 4497-4501, 2017 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-28617606

RESUMO

Additive manufacturing processes enable fabrication of complex and functional three-dimensional (3D) objects ranging from engine parts to artificial organs. Photopolymerization, which is the most versatile technology enabling such processes through 3D printing, utilizes photoinitiators that break into radicals upon light absorption. We report on a new family of photoinitiators for 3D printing based on hybrid semiconductor-metal nanoparticles. Unlike conventional photoinitiators that are consumed upon irradiation, these particles form radicals through a photocatalytic process. Light absorption by the semiconductor nanorod is followed by charge separation and electron transfer to the metal tip, enabling redox reactions to form radicals in aerobic conditions. In particular, we demonstrate their use in 3D printing in water, where they simultaneously form hydroxyl radicals for the polymerization and consume dissolved oxygen that is a known inhibitor. We also demonstrate their potential for two-photon polymerization due to their giant two-photon absorption cross section.

8.
Langmuir ; 33(22): 5519-5526, 2017 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-28497974

RESUMO

Carbon nanotubes (CNTs) and semiconductor nanocrystals (SCNCs) are known to be interesting donor-acceptor partners due to their unique optical and electronic properties. These exciting features have led to the development of novel composites based on these two nanomaterials and to their characterization for use in various applications, such as components in sensors, transistors, solar cells and biomedical devices. Two approaches based on covalent and noncovalent methods have been suggested for coupling the SCNCs to CNTs. Most covalent conjugation methods used so far were found to disrupt the electronic structure of the CNTs or interfere with charge transfer in the CNT-SCNC interface. Moreover, it offers random and poorly organized nanoparticle coatings. Therefore, noncovalent methods are considered to be ideal for better electronic coupling. However, a key common drawback of noncovalent methods is the lack of stability which hampers their applicability. In this article, a method has been developed to couple semiconductor seeded nanorods onto CNTs through π-π interactions. The CNTs and pyrene conjugated SCNC hybrid materials were characterized by both microscopic and spectroscopic techniques. Fluorescence and photocurrent measurements suggest the proposed pi-stacking approach results in a strong electronic coupling between the CNTs and the SCNCs leading to better photocurrent efficiency than that of a covalent conjugation method reported using similar SCNC material. Overall, the CNT-SCNC films reported in the present study open the scope for the fabrication of optoelectronic devices for various applications.

9.
ACS Nano ; 11(3): 3038-3051, 2017 03 28.
Artigo em Inglês | MEDLINE | ID: mdl-28196324

RESUMO

Quantum dots (QDs), semiconductor nanocrystals, are fluorescent nanoparticles of growing interest as an imaging tool of a diseased tissue. However, a major concern is their biocompatibility, cytotoxicity, and fluorescence instability in biological milieu, impeding their use in biomedical applications, in general, and for inflammation imaging, in particular. In addition, for an efficient fluorescent signal at the desired tissue, and avoiding systemic biodistribution and possible toxicity, targeting is desired. We hypothesized that phagocytic cells of the innate immunity system (mainly circulating monocytes) can be exploited as transporters of specially designed liposomes containing QDs to the inflamed tissue. We developed a liposomal delivery system of QDs (LipQDs) characterized with high encapsulation yield, enhanced optical properties including far-red emission wavelength and fluorescent stability, high quantum yield, and protracted fluorescent decay lifetime. Treatment with LipQDs, rather than free QDs, exhibited high accumulation and retention following intravenous administration in carotid-injured rats (an inflammatory model). QD-monocyte colocalization was detected in the inflamed arterial segment only following treatment with LipQDs. No cytotoxicity was observed following LipQD treatment in cell cultures, and changes in liver enzymes and gross histopathological changes were not detected in mice and rats, respectively. Our results suggest that the LipQD formulation could be a promising strategy for imaging inflammation.


Assuntos
Sistemas de Liberação de Medicamentos , Inflamação/diagnóstico por imagem , Monócitos/química , Monócitos/metabolismo , Imagem Óptica , Pontos Quânticos/química , Animais , Compostos de Cádmio/química , Células Cultivadas , Lipossomos/química , Lipossomos/farmacocinética , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Células RAW 264.7 , Ratos , Ratos Endogâmicos , Compostos de Selênio/química , Sulfetos/química , Distribuição Tecidual , Compostos de Zinco/química
10.
Nano Lett ; 16(7): 4266-73, 2016 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-27224678

RESUMO

Semiconductor-metal hybrid nanoparticles manifest efficient light-induced spatial charge separation at the semiconductor-metal interface, as demonstrated by their use for hydrogen generation via water splitting. Here, we pioneer a study of their functionality as efficient photocatalysts for the formation of reactive oxygen species. We observed enhanced photocatalytic activity forming hydrogen peroxide, superoxide, and hydroxyl radicals upon light excitation, which was significantly larger than that of the semiconductor nanocrystals, attributed to the charge separation and the catalytic function of the metal tip. We used this photocatalytic functionality for modulating the enzymatic activity of horseradish peroxidase as a model system, demonstrating the potential use of hybrid nanoparticles as active agents for controlling biological processes through illumination. The capability to produce reactive oxygen species by illumination on-demand enhances the available peroxidase-based tools for research and opens the path for studying biological processes at high spatiotemporal resolution, laying the foundation for developing novel therapeutic approaches.


Assuntos
Luz , Nanopartículas Metálicas , Espécies Reativas de Oxigênio/química , Semicondutores , Fenômenos Biológicos , Peroxidase do Rábano Silvestre/química
11.
Nanoscale ; 7(45): 19193-200, 2015 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-26526222

RESUMO

Semiconductor nanocrystals exhibit unique fluorescence properties which are tunable in size, shape and composition. The high quantum yield and enhanced stability have led to their use in biomedical imaging and flat panel displays. Here, semiconductor nanorod based inkjet inks are presented, overcoming limitations of the commonly reported quantum dots in printing applications. Fluorescent seeded nanorods were found to be outstanding candidates for fluorescent inks, due to their low particle-particle interactions and negligible self-absorption. This is manifested by insignificant emission shifts upon printing, even in highly concentrated printed layers and by maintenance of a high fluorescence quantum yield, unlike quantum dots which exhibit fluorescence wavelength shifts and quenching effects. This behavior results from the reduced absorption/emission overlap, accompanied by low energy transfer efficiencies between the nanorods as supported by steady state and time resolved fluorescence measurements. The new seeded nanorod inks enable patterning of thin fluorescent layers, for demanding light emission applications such as signage and displays.

12.
ACS Appl Mater Interfaces ; 7(38): 21107-14, 2015 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-26334672

RESUMO

Singlet oxygen ((1)O2) generated upon photostimulation of photosensitizer molecules is a highly reactive specie which is utilized in photodynamic therapy. Recent studies have shown that semiconductor nanoparticles can be used as donors in fluorescence resonance energy transfer (FRET) process to excite attached photosensitizer molecules. In these studies, their unique properties, such as low nanoscale size, long-term photostability, wide broad absorbance band, large absorption cross section, and narrow and tunable emission bands were used to provide advantages over the traditional methods to produce singlet oxygen. Previous studies that achieved this goal, however, showed some limitations, such as low FRET efficiency, poor colloidal stability, nonspecific interactions, and/or complex preparation procedure. In this work, we developed and characterized a novel system of semiconductor quantum rods (QRs) and the photosensitizer meso-tetra(hydroxyphenyl) chlorin (mTHPC), as a model system that produces singlet oxygen without these limitations. A simple two-step preparation method is shown; Hydrophobic CdSe/CdS QRs are solubilized in aqueous solutions by encapsulation with lecithin and PEGylated phospholipid (PEG-PL) of two lipid lengths: PEG350 or PEG2000. Then, the hydrophobic photosensitizer mTHPC, was intercalated into the new amphiphilic PEG-PL coating of the QR, providing a strong attachment to the nanoparticle without covalent linkage. These PEGylated QR (eQR)-mTHPC nanocomposites show efficient FRET processes upon light stimulation of the QR component which results in efficient production of singlet oxygen. The results demonstrate the potential for future use of this concept in photodynamic therapy schemes.


Assuntos
Transferência Ressonante de Energia de Fluorescência , Fosfolipídeos/química , Fármacos Fotossensibilizantes/química , Polietilenoglicóis/química , Pontos Quânticos/química , Fluorescência , Cinética , Mesoporfirinas/química , Nanocompostos/química , Pontos Quânticos/ultraestrutura , Oxigênio Singlete/química
13.
Small ; 11(4): 462-71, 2015 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-25207751

RESUMO

Hybrid semiconductor-metal nanoparticles are interesting materials for use as photocatalysts due to their tunable properties and chemical processibility. Their function in the evolution of hydrogen in photocatalytic water splitting is the subject of intense current investigation. Here, the effects of the surface coatings on the photocatalytic function are studied, with Au-tipped CdS nanorods as a model hybrid nanoparticle system. Kinetic measurements of the hydrogen evolution rate following photocatalytic water reduction are performed on similar nanoparticles but with different surface coatings, including various types of thiolated alkyl ligands and different polymer coatings. The apparent hydrogen evolution quantum yields are found to strongly depend on the surface coating. The lowest yields are observed for thiolated alkyl ligands. Intermediate values are obtained with L-glutathione and poly(styrene-co-maleic anhydride) polymer coatings. The highest efficiency is obtained for polyethylenimine (PEI) polymer coating. These pronounced differences in the photocatalytic efficiencies are correlated with ultrafast transient absorption spectroscopy measurements, which show a faster bleach recovery for the PEI-coated hybrid nanoparticles, consistent with faster and more efficient charge separation. These differences are primarily attributed to the effects of surface passivation by the different coatings affecting the surface trapping of charge carriers that compete with effective charge separation required for the photocatalysis. Further support of this assignment is provided from steady-state emission and time-resolved spectral measurements, performed on related strongly fluorescing CdSe/CdS nanorods. The control and understanding of the effect of the surface coating of the hybrid nanosystems on the photocatalytic processes is of importance for the potential application of hybrid nanoparticles as photocatalysts.

14.
Proc Natl Acad Sci U S A ; 112(5): E467-71, 2015 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-25535364

RESUMO

Recent international terror outbreaks notably involve long-term mental health risks to the exposed population, but whether physical health risks are also anticipated has remained unknown. Here, we report fear of terror-induced annual increases in resting heart rate (pulse), a notable risk factor of all-cause mortality. Partial least squares analysis based on 325 measured parameters successfully predicted annual pulse increases, inverse to the expected age-related pulse decline, in approximately 4.1% of a cohort of 17,380 apparently healthy active Israeli adults. Nonbiased hierarchical regression analysis among 27 of those parameters identified pertinent fear of terror combined with the inflammatory biomarker C-reactive protein as prominent coregulators of the observed annual pulse increases. In comparison, basal pulse primarily depended on general physiological parameters and reduced cholinergic control over anxiety and inflammation, together indicating that consistent exposure to terror threats ignites fear-induced exacerbation of preexisting neuro-immune risks of all-cause mortality.


Assuntos
Proteína C-Reativa/fisiologia , Medo , Frequência Cardíaca/fisiologia , Adulto , Humanos , Inflamação/fisiopatologia
15.
Nano Lett ; 14(11): 6685-92, 2014 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-25350365

RESUMO

We report the development of a semiconductor nanorod-carbon nanotube based platform for wire-free, light induced retina stimulation. A plasma polymerized acrylic acid midlayer was used to achieve covalent conjugation of semiconductor nanorods directly onto neuro-adhesive, three-dimensional carbon nanotube surfaces. Photocurrent, photovoltage, and fluorescence lifetime measurements validate efficient charge transfer between the nanorods and the carbon nanotube films. Successful stimulation of a light-insensitive chick retina suggests the potential use of this novel platform in future artificial retina applications.


Assuntos
Materiais Biomiméticos/química , Nanotubos de Carbono/química , Nanotubos/química , Próteses Neurais , Retina/fisiologia , Semicondutores , Acrilatos/química , Animais , Biomimética , Embrião de Galinha , Luz , Nanotubos/ultraestrutura , Nanotubos de Carbono/ultraestrutura , Polimerização
16.
Mol Med ; 20: 38-45, 2014 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-24395570

RESUMO

Parasympathetic activity influences long-term outcome in patients with cardiovascular disease, but the underlying mechanism(s) linking parasympathetic activity and the occurrence of major adverse cardiovascular events (MACEs) are incompletely understood. The aim of this pilot study was to evaluate the association between serum cholinesterase activities as parasympathetic biomarkers and the risk for the occurrence of MACEs. Cholinergic status was determined by measuring the cumulative capacity of serum acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) to hydrolyze the AChE substrate acetylthiocholine. Cholinergic status was evaluated in randomly selected patients undergoing cardiac catheterization. The patients were divided into two groups of 100 patients in each group, with or without occurrence of MACEs during a follow-up period of 40 months. Cox regression models adjusted for potential clinical, metabolic and inflammatory confounders served to evaluate association with clinical outcome. We found that patients with MACE presented lower cholinergic status and AChE values at catheterization (1,127 ± 422 and 359 ± 153 nmol substrate hydrolyzed per minute per milliliter, respectively) than no-MACE patients (1,760 ± 546 and 508 ± 183 nmol substrate hydrolyzed per minute per milliliter, p < 0.001 and p < 0.001, respectively), whose levels were comparable to those of matched healthy controls (1,622 ± 303 and 504 ± 126 nmol substrate hydrolyzed per minute per milliliter, respectively). In a multivariate analysis, patients with AChE or total cholinergic status values below median showed conspicuously elevated risk for MACE (hazard ratio 1.85 [95% confidence interval [CI] 1.09-3.15, p = 0.02] and 2.21 [95% CI 1.22-4.00, p = 0.009]) compared with those above median, even after adjusting for potential confounders. We conclude that parasympathetic dysfunction expressed as reduced serum AChE and AChE activities in patients compared to healthy controls can together reflect impaired parasympathetic activity. This impairment predicts the risk of MACE up to 40 months in such patients. Monitoring these parasympathetic parameters might help in the risk stratification of patients with cardiovascular disease.


Assuntos
Acetilcolinesterase/sangue , Butirilcolinesterase/sangue , Cateterismo Cardíaco/efeitos adversos , Doenças Cardiovasculares/sangue , Acetilcolina/sangue , Acetilcolinesterase/metabolismo , Biomarcadores/sangue , Butirilcolinesterase/metabolismo , Doenças Cardiovasculares/patologia , Doenças Cardiovasculares/prevenção & controle , Estudos de Casos e Controles , Humanos , Modelos Moleculares , Análise Multivariada , Conformação Proteica , Estrutura Secundária de Proteína , Análise de Regressão
17.
J Mol Neurosci ; 53(3): 306-15, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24258317

RESUMO

Selective serotonin reuptake inhibitors (SSRIs) show anti-inflammatory effects, suggesting a possible interaction with both Toll-like-receptor 4 (TLR4) responses and cholinergic signaling through as yet unclear molecular mechanism(s). Our results of structural modeling support the concept that the antidepressant fluoxetine physically interacts with the TLR4-myeloid differentiation factor-2 complex at the same site as bacterial lipopolysaccharide (LPS). We also demonstrate reduced LPS-induced pro-inflammatory interleukin-6 and tumor necrosis factor alpha in human peripheral blood mononuclear cells preincubated with fluoxetine. Furthermore, we show that fluoxetine intercepts the LPS-induced decreases in intracellular acetylcholinesterase (AChE-S) and that AChE-S interacts with the nuclear factor kappa B (NFκB)-activating intracellular receptor for activated C kinase 1 (RACK1). This interaction may prevent NFκB activation by residual RACK1 and its interacting protein kinase PKCßII. Our findings attribute the anti-inflammatory properties of SSRI to surface membrane interference with leukocyte TLR4 activation accompanied by intracellular limitation of pathogen-inducible changes in AChE-S, RACK1, and PKCßII.


Assuntos
Acetilcolinesterase/metabolismo , Anti-Inflamatórios/farmacologia , Fluoxetina/farmacologia , Proteínas de Ligação ao GTP/metabolismo , Proteínas de Neoplasias/metabolismo , Receptores de Superfície Celular/metabolismo , Inibidores de Captação de Serotonina/farmacologia , Acetilcolinesterase/química , Sequência de Aminoácidos , Sítios de Ligação , Proteínas Ligadas por GPI/química , Proteínas Ligadas por GPI/metabolismo , Proteínas de Ligação ao GTP/química , Humanos , Interleucina-6/genética , Interleucina-6/metabolismo , Lipopolissacarídeos/farmacologia , Simulação de Acoplamento Molecular , Dados de Sequência Molecular , Monócitos/efeitos dos fármacos , Monócitos/metabolismo , Proteínas de Neoplasias/química , Ligação Proteica , Proteína Quinase C beta/metabolismo , Receptores de Quinase C Ativada , Receptores de Superfície Celular/química , Receptor 4 Toll-Like/química , Receptor 4 Toll-Like/metabolismo
18.
J Cell Mol Med ; 15(8): 1747-56, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20807286

RESUMO

The metabolic syndrome (MetS) is a risk factor for type 2 diabetes mellitus (T2DM). However, the mechanisms underlying the transition from MetS to T2DM are unknown. Our goal was to study the potential contribution of butyrylcholinesterase (BChE) to this process. We first determined the hydrolytic activity of BChE in serum from MetS, T2DM and healthy individuals. The 'Kalow' variant of BChE (BChE-K), which has been proposed to be a risk factor for T2DM, was genotyped in the last two groups. Our results show that in MetS patients serum BChE activity is elevated compared to T2DM patients and healthy controls (P < 0.001). The BChE-K genotype showed similar prevalence in T2DM and healthy individuals, excluding this genotype as a risk factor for T2DM. However, the activity differences remained unexplained. Previous results from our laboratory have shown BChE to attenuate the formation of ß-amyloid fibrils, and protect cultured neurons from their cytotoxicity. Therefore, we next studied the in vitro interactions between recombinant human butyrylcholinesterase and amylin by surface plasmon resonance, Thioflavine T fluorescence assay and cross-linking, and used cultured pancreatic ß cells to test protection by BChE from amylin cytotoxicity. We demonstrate that BChE interacts with amylin through its core domain and efficiently attenuates both amylin fibril and oligomer formation. Furthermore, application of BChE to cultured ß cells protects them from amylin cytotoxicity. Taken together, our results suggest that MetS-associated BChE increases could protect pancreatic ß-cells in vivo by decreasing the formation of toxic amylin oligomers.


Assuntos
Butirilcolinesterase/metabolismo , Células Secretoras de Insulina/metabolismo , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Síndrome Metabólica/metabolismo , Adulto , Idoso , Sequência de Aminoácidos , Butirilcolinesterase/química , Butirilcolinesterase/genética , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Feminino , Genótipo , Humanos , Immunoblotting , Polipeptídeo Amiloide das Ilhotas Pancreáticas/química , Polipeptídeo Amiloide das Ilhotas Pancreáticas/farmacologia , Masculino , Síndrome Metabólica/sangue , Síndrome Metabólica/genética , Pessoa de Meia-Idade , Modelos Moleculares , Dados de Sequência Molecular , Multimerização Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/farmacologia , Ressonância de Plasmônio de Superfície
19.
ACS Chem Neurosci ; 2(3): 141-50, 2011 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-22778863

RESUMO

Butyrylcholinesterase (BChE) is the major acetylcholine hydrolyzing enzyme in peripheral mammalian systems. It can either reside in the circulation or adhere to cells and tissues and protect them from anticholinesterases, including insecticides and poisonous nerve gases. In humans, impaired cholinesterase functioning is causally involved in many pathologies, including Alzheimer's and Parkinson's diseases, trait anxiety, and post stroke conditions. Recombinant cholinesterases have been developed for therapeutic use; therefore, it is important to follow their in vivo path, location, and interactions. Traditional labeling methods, such as fluorescent dyes and proteins, generally suffer from sensitivity to environmental conditions, from proximity to different molecules or special enzymes which can alter them, and from relatively fast photobleaching. In contrast, emerging development in synthesis and surface engineering of semiconductor nanocrystals enable their use to detect and follow molecules in biological milieus at high sensitivity and in real time. Therefore, we developed a platform for conjugating highly purified recombinant human BChE dimers (rhBChE) to CdSe/CdZnS quantum dots (QDs). We report the development and characterization of highly fluorescent aqueous soluble QD-rhBChE conjugates, present maintenance of hydrolytic activity, inhibitor sensitivity, and adherence to the membrane of cultured live cells of these conjugates, and outline their advantageous features for diverse biological applications.


Assuntos
Butirilcolinesterase/química , Butirilcolinesterase/metabolismo , Pontos Quânticos , Animais , Adesão Celular/fisiologia , Células Cultivadas , Humanos , Camundongos , Ligação Proteica/fisiologia , Coloração e Rotulagem/métodos , Especificidade por Substrato/fisiologia
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