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1.
Dermatology ; 240(3): 414-424, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38493762

RESUMO

INTRODUCTION: Generalized pustular psoriasis (GPP) is a rare and chronic, debilitating skin condition characterized, in its acute flare phase, by clinically severe and potentially life-threatening systemic manifestations. Data on GPP are still scanty, particularly in Europe and at a national level. The aim of this study was to provide expert indications on several disease-related and patient-related aspects of GPP, with specific focus to the Italian context. METHODS: We conducted an iterative eDelphi study following the recommended criteria for reporting methods and results. After a thorough bibliographic review aimed to identify unknown or controversial issues in GPP, the following areas were investigated through a few specific questions/statements for each area: (1) disease epidemiology; (2) disease characteristics, with specific interest toward GPP flares; (3) diagnosis and diagnostic delay; (4) GPP treatment; (5) GPP patient journey and use of healthcare resources in Italy; (6) unmet needs and quality of life. An Executive Board of 9 principal investigators revised and approved the topics to be examined and overviewed the whole project. A total of 35 experts from different Italian areas, including 34 board-certified Italian dermatologists and 1 representative of patients' associations, took part in the study. RESULTS: A high agreement in responses from Italian experts emerged during two eDelphi iterations on - among several other aspects - GPP prevalence and incidence in Italy, use of European Rare and Severe Psoriasis Expert Network diagnostic criteria, flare frequency and duration, best diagnostic and care pathway, and main unmet needs of Italian patients. On the other hand, a broad spectrum of treatments (of different drug classes) was reported both in the acute and chronic phases of GPP, and no consensus on the issue was thus achieved. CONCLUSIONS: Consensus findings from this Delphi study of GPP experts may be useful to fill gaps of knowledge and improve awareness of this rare disease, as well as to help clinical and public health management of GPP in Italy.


Assuntos
Consenso , Técnica Delphi , Psoríase , Psoríase/epidemiologia , Psoríase/terapia , Humanos , Itália/epidemiologia , Qualidade de Vida , Necessidades e Demandas de Serviços de Saúde , Diagnóstico Tardio/estatística & dados numéricos
2.
Analyst ; 148(18): 4365-4372, 2023 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-37548234

RESUMO

Raman MicroSpectroscopy (RMS) is a powerful label-free tool to probe the effects of drugs at a cellular/subcellular level. It is important, however, to be able to extract relevant biochemical and kinetic spectroscopic signatures of the specific cellular responses. In the present study, a combination of Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) and Principal Component Analysis (PCA) is used to analyse the RMS data for the example of exposure of primary Oral Squamous Carcinoma Cells (OSCC) to the chemotherapeutic agent cisplatin. Dosing regimens were established by cytotoxicity assays, and the effects of the drug on cellular spectral profiles were monitored from 16 to 72 hours post-exposure using an apoptosis assay, to establish the relative populations of viable (V), early (EA) and late apoptotic/dead (LA/D) cells after the drug treatment. Based on a kinetic model of the progression from V > EA > D, MCR-ALS regression analysis of the RMS responses was able to extract spectral profiles associated with each stage of the cellular responses, enabling a quantitative comparison of the response rates for the respective drug treatments. Moreover, PCA was used to compare the spectral profiles of the viable cells exposed to the drug. Spectral differences were highlighted in the early stages (16 hours exposure), indicative of the initial cellular response to the drug treatment, and also in the late stages (48-72 hours exposure), representing the cell death pathway. The study demonstrates that RMS coupled with multivariate analysis can be used to quantitatively monitor the progression of cellular responses to different drugs, towards future applications for label-free, in vitro, pre-clinical screening.


Assuntos
Carcinoma de Células Escamosas , Cisplatino , Humanos , Cisplatino/farmacologia , Análise dos Mínimos Quadrados , Análise Espectral Raman/métodos , Carcinoma de Células Escamosas/tratamento farmacológico , Análise Multivariada
3.
Int J Mol Sci ; 24(7)2023 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-37047038

RESUMO

The main protease (Mpro or 3CLpro) is an enzyme that is evolutionarily conserved among different genera of coronaviruses. As it is essential for processing and maturing viral polyproteins, Mpro has been identified as a promising target for the development of broad-spectrum drugs against coronaviruses. Like SARS-CoV and MERS-CoV, the mature and active form of SARS-CoV-2 Mpro is a dimer composed of identical subunits, each with a single active site. Individual monomers, however, have very low or no catalytic activity. As such, inhibition of Mpro can be achieved by molecules that target the substrate binding pocket to block catalytic activity or target the dimerization process. In this study, we investigated GC376, a transition-state analog inhibitor of the main protease of feline infectious peritonitis coronavirus, and Nirmatrelvir (NMV), an oral, bioavailable SARS-CoV-2 Mpro inhibitor with pan-human coronavirus antiviral activity. Our results show that both GC376 and NMV are capable of strongly binding to SARS-CoV-2 Mpro and altering the monomer-dimer equilibrium by stabilizing the dimeric state. This behavior is proposed to be related to a structured hydrogen-bond network established at the Mpro active site, where hydrogen bonds between Ser1' and Glu166/Phe140 are formed in addition to those achieved by the latter residues with GC376 or NMV.


Assuntos
COVID-19 , SARS-CoV-2 , Humanos , SARS-CoV-2/metabolismo , Cisteína Endopeptidases/metabolismo , Inibidores de Proteases/farmacologia , Inibidores de Proteases/química , Antivirais/farmacologia , Antivirais/química , Simulação de Acoplamento Molecular
4.
Int J Mol Sci ; 23(23)2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36499432

RESUMO

In this study, the transdermal fate of vesicular nanosystems was investigated. Particularly, ethosomes based on phosphatidylcholine 0.9% w/w and transethosomes based on phosphatidylcholine 0.9 or 2.7% w/w plus polysorbate 80 0.3% w/w as an edge activator were prepared and characterized. The vesicle mean size, morphology and deformability were influenced by both phosphatidylcholine and polysorbate 80. Indeed, the mean diameters of ethosome were around 200 nm, while transethosome's mean diameters were 146 or 350 nm in the case of phosphatidylcholine 0.9 or 2.7%, w/w, respectively. The highest deformability was achieved by transethosomes based on phosphatidylcholine 0.9%, w/w. The three types of vesicular nanosystems were applied on explanted human skin maintained in a bioreactor. Transmission electron microscopy demonstrated that all vesicles were able to enter the skin, keeping their structural integrity. Notably, the vesicle penetration capability was influenced by their physical-chemical features. Indeed, ethosomes reached keratinocytes and even the dermis, phosphatidylcholine 0.9% transethosomes were found in keratinocytes and phosphatidylcholine 2.7% transethosomes were found only in corneocytes of the outer layer. These findings open interesting perspectives for a differentiated application of these vesicles for transdermal drug delivery as a function of the cutaneous pathology to be addressed.


Assuntos
Portadores de Fármacos , Absorção Cutânea , Humanos , Portadores de Fármacos/química , Pele/metabolismo , Administração Cutânea , Fosfatidilcolinas/metabolismo , Lipossomos/química
5.
Langmuir ; 36(35): 10387-10396, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32787014

RESUMO

We evaluate, by means of synchrotron small-angle X-ray scattering, the shape and mutual interactions of DNA tetravalent nanostars as a function of temperature in both the gas-like state and across the gel transition. To this end, we calculate the form factor from coarse-grained molecular dynamics simulations with a novel method that includes hydration effects; we approximate the radial interaction of DNA nanostars as a hard-sphere potential complemented by a repulsive and an attractive Yukawa term; and we predict the structure factors by exploiting the perturbative random phase approximation of the Percus-Yevick equation. Our approach enables us to fit all the data by selecting the particle radius and the width and amplitude of the attractive potential as free parameters. We determine the evolution of the structure factor across gelation and detect subtle changes of the effective interparticle interactions, that we associate to the temperature and concentration dependence of the particle size. Despite the approximations, the approach here adopted offers new detailed insights into the structure and interparticle interactions of this fascinating system.


Assuntos
Coloides , DNA , Géis , Espalhamento a Baixo Ângulo , Difração de Raios X
6.
J Chem Inf Model ; 60(10): 5265-5281, 2020 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-32866007

RESUMO

The in solution synchrotron small-angle X-ray scattering SAXS technique has been used to investigate an intrinsically disordered protein (IDP) related to Parkinson's disease, the α-synuclein (α-syn), in prefibrillar diluted conditions. SAXS experiments have been performed as a function of temperature and concentration on the wild type (WT) and on the three pathogenic mutants G51D, E46K, and A53T. To identify the conformers that populate WT α-syn and the pathogenic mutants in prefibrillar conditions, scattering data have been analyzed by a new variational bayesian weighting method (VBWSAS) based on an ensemble of conformers, which includes unfolded monomers, trimers, and tetramers, both in helical-rich and strand-rich forms. The developed VBWSAS method uses a thermodynamic scheme to account for temperature and concentration effects and considers long-range protein-protein interactions in the framework of the random phase approximation. The global analysis of the whole set of data indicates that WT α-syn is mostly present as unfolded monomers and trimers (helical-rich trimers at low T and strand-rich trimers at high T), but not tetramers, as previously derived by several studies. On the contrary, different conformer combinations characterize mutants. In the α-syn G51D mutant, the most abundant aggregates at all the temperatures are strand-rich tetramers. Strand-rich tetramers are also the predominant forms in the A53T mutant, but their weight decreases with temperature. Only monomeric conformers, with a preference for the ones with the smallest sizes, are present in the E46K mutant. The derived conformational behavior then suggests a different availability of species prone to aggregate, depending on mutation, temperature, and concentration and accounting for the different neurotoxicity of α-syn variants. Indeed, this approach may be of pivotal importance to describe conformational and aggregational properties of other IDPs.


Assuntos
alfa-Sinucleína , Teorema de Bayes , Mutação , Espalhamento a Baixo Ângulo , Termodinâmica , Difração de Raios X , Raios X , alfa-Sinucleína/genética
7.
Molecules ; 25(23)2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-33266241

RESUMO

Biofilm production is regulated by the Quorum Sensing system. Nowadays, Quorum Sensing represents an appealing target to design new compounds to increase antibiotics effects and avoid development of antibiotics multiresistance. In this research the use of liposomes to target two novel synthetic biofilm inhibitors is presented, focusing on a preformulation study to select a liposome composition for in vitro test. Five different liposome (LP) formulations, composed of phosphatidyl choline, cholesterol and charged surfactant (2:1:1, molar ratio) have been prepared by direct hydration and extrusion. As charged surfactants dicetyl phosphate didecyldimethylammonium chloride, di isobutyl phenoxy ethyl dimethyl benzyl ammonium chloride and stearylamine (SA) and have been used. Liposome charge, size and morphology were investigated by zeta potential, photon correlation spectroscopy, small angle x-ray spectroscopy and electron microscopy. LP-SA was selected for the loading of biofilm inhibitors and subjected to high performance liquid chromatography for entrapment capacity evaluation. LP-SA loaded inhibitors showed a higher diameter (223.6 nm) as compared to unloaded ones (205.7 nm) and a dose-dependent anti-biofilm effect mainly after 48 h of treatment, while free biofilm inhibitors loose activity. In conclusion, our data supported the use of liposomes as a strategy to enhance biofilm inhibitors effect.


Assuntos
Antibacterianos/administração & dosagem , Bactérias/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Sistemas de Liberação de Medicamentos , Desenho de Fármacos , Lipossomos/administração & dosagem , Nanopartículas/administração & dosagem , Percepção de Quorum , Antibacterianos/química , Lipossomos/química , Nanopartículas/química
8.
Molecules ; 25(6)2020 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-32210106

RESUMO

Ellagic acid (EA) is a potent antioxidant substance of natural origin characterized by poor biopharmaceutical properties and low solubility in water that limit its use. The aim of the present study was to develop lipid-based nanoparticle formulations able to encapsulate EA for dermal delivery. The EA-loaded nanoparticles were prepared using two different lipid compositions, namely tristearin/tricaprylin (NLC-EA1) and tristearin/labrasol (NLC-EA2). The influence of formulations on size, entrapment efficiency, and stability of EA-loaded nanoparticles was investigated. Cryo-TEM and small-angle X-ray scattering (SAXS) analyses showed that no morphological differences are evident among all the types of loaded and unloaded nanostructured lipid carriers (NLCs). The macroscopic aspect of both NLC-EA1 and NLC-EA2 did not change with time. No difference in size was appreciable between empty and drug-containing NLC, thus the nanoparticle diameter was not affected by the presence of EA and in general no variations of the diameters occurred during this time. The entrapment efficiency of both EA-loaded nanoparticles was almost quantitative. In addition, NLC-EA1 maintained EA stability for almost two months, while NLC-EA2 up to 40 days. FRAP (Ferric reducing ability of plasma) assay showed an antioxidant activity around 60% for both the loaded NLC, as compared to the solution. Although both types of NLC are characterized by some toxicity on HaCaT cells, NLC-EA1 are less cytotoxic than NLC-EA2. Taken together these results demonstrated that the inclusion of EA within NLC could improve the water solubility, allowing for a reduction of the dosage. Moreover, both types of NLC-EA maintained a high antioxidant effect and low toxicity.


Assuntos
Antioxidantes , Portadores de Fármacos , Ácido Elágico , Nanopartículas/química , Antioxidantes/química , Antioxidantes/farmacocinética , Antioxidantes/farmacologia , Caprilatos/química , Caprilatos/farmacocinética , Caprilatos/farmacologia , Linhagem Celular , Preparações de Ação Retardada/química , Preparações de Ação Retardada/farmacocinética , Preparações de Ação Retardada/farmacologia , Portadores de Fármacos/química , Portadores de Fármacos/farmacocinética , Portadores de Fármacos/farmacologia , Ácido Elágico/química , Ácido Elágico/farmacocinética , Ácido Elágico/farmacologia , Glicerídeos/química , Glicerídeos/farmacocinética , Glicerídeos/farmacologia , Humanos , Triglicerídeos/química , Triglicerídeos/farmacocinética , Triglicerídeos/farmacologia
9.
Soft Matter ; 15(11): 2315-2318, 2019 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-30806419

RESUMO

Aqueous solutions of guanosine-5'-monophosphates (GMP) - known to form G-quadruplexes and liquid crystal phases - can be induced to turn into high water content gels by the addition of guanosine (Gua). By a combination of Light Scattering (LS) and AFM we show that Gua/GMP hydrogels are microscopically heterogeneous, formed by Gua-rich disordered microcoils of intertwined filaments ("knots") connected by GMP-rich long linear threads. The different thermal stability of knots and threads controls the gel transition.

10.
Org Biomol Chem ; 17(10): 2759-2769, 2019 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-30785179

RESUMO

Addition of azobenzene-derivative 1 in its E configuration to an aqueous solution containing various guanosine borate esters induces a helical G-quartet based self-organization, stabilized by intercalation of the dye. The process is driven, in a domino fashion, by the initial host-guest interaction between the dye and a specific guanosine borate diester, whose structure can be thus assigned. This inclusion complex templates the formation of G-quartets. The quartets, in turn, pile up to form a supramolecular G-quadruplex structure, in which other G species present in solution are progressively included. The G-quadruplex can be reversibly broken and reformed by photoisomerization of the dye. This hierarchical and photosensitive self-assembly is unprecedented for simple guanosine derivatives.


Assuntos
Compostos Azo/química , Ácidos Bóricos/química , Quadruplex G , Guanosina/química , Processos Fotoquímicos , Modelos Moleculares
11.
Soft Matter ; 14(15): 2938-2948, 2018 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-29611597

RESUMO

Supramolecular hydrogels formed from the self-assembly of low molecular weight derivatives are very attractive systems, because of their potential applications in nano- and bio-technology. In this paper, the stable and transparent hydrogels observed in binary mixtures of guanosine derivatives (G), namely guanosine 5'-monophosphate (GMP) and guanosine (Gua), dissolved in water (at volume fractions larger than 0.95), were investigated by microscopy techniques and Small Angle X-ray Scattering (SAXS). The results confirm the presence of G-quadruplexes, chiral cylindrical rods obtained by the regular stacking of self-assembled planar cyclic guanosine quartets. However, the addition of Gua determines the formation of very stable hydrogels able to trap large amounts of water (up to a volume fraction of 0.99) and characterised by an unusual anisotropic order. A modified lateral helix-to-helix interaction pattern, tuned by Gua, is suggested to be responsible for the supramolecular gelation and the stability of the hydrogels during swelling.

12.
Biophys J ; 113(8): 1685-1696, 2017 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-29045863

RESUMO

The analysis of the α-synuclein (aS) aggregation process, which is involved in Parkinson's disease etiopathogenesis, and of the structural feature of the resulting amyloid fibrils may shed light on the relationship between the structure of aS aggregates and their toxicity. This may be considered a paradigm of the ground work needed to tackle the molecular basis of all the protein-aggregation-related diseases. With this aim, we used chemical and physical dissociation methods to explore the structural organization of wild-type aS fibrils. High pressure (in the kbar range) and alkaline pH were used to disassemble fibrils to collect information on the hierarchic pathway by which distinct ß-sheets sequentially unfold using the unique possibility offered by high-pressure Fourier transform infrared spectroscopy. The results point toward the formation of kinetic traps in the energy landscape of aS fibril disassembly and the presence of transient partially folded species during the process. Since we found that the dissociation of wild-type aS fibrils by high pressure is reversible upon pressure release, the disassembled molecules likely retain structural information that favors fibril reformation. To deconstruct the role of the different regions of aS sequence in this process, we measured the high-pressure dissociation of amyloids formed by covalent chimeric dimers of aS (syn-syn) and by the aS deletion mutant that lacks the C-terminus, i.e., aS (1-99). The results allowed us to single out the role of dimerization and that of the C-terminus in the complete maturation of fibrillar aS.


Assuntos
Amiloide/metabolismo , alfa-Sinucleína/metabolismo , Amiloide/química , Dicroísmo Circular , Escherichia coli , Concentração de Íons de Hidrogênio , Microscopia de Força Atômica , Microscopia Eletrônica de Transmissão , Modelos Moleculares , Mutação , Pressão , Conformação Proteica em Folha beta , Domínios Proteicos , Dobramento de Proteína , Multimerização Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , alfa-Sinucleína/química
13.
Arch Biochem Biophys ; 627: 46-55, 2017 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-28624352

RESUMO

α-synuclein amyloid fibrils are found in surviving neurons of Parkinson's disease affected patients, but the role they play in the disease development is still under debate. A growing number of evidences points to soluble oligomers as the major cytotoxic species, while insoluble fibrillar aggregates could even play a protection role. In this work, we investigate α-synuclein fibrils dissociation induced at high pressure by means of Small Angle X-ray Scattering and Fourier Transform Infrared Spectroscopy. Fibrils were produced from wild type α-synuclein and two familial mutants, A30P and A53T. Our results enlighten the different reversible nature of α-synuclein fibrils fragmentation at high pressure and suggest water excluded volumes presence in the fibrils core. Wild type and A30P species stabilized at high pressure are highly amyloidogenic and quickly re-associate into fibrils upon decompression, while A53T species shows a partial reversibility of the process likely due to the presence of an intermediate oligomeric state stabilized at high pressure. The amyloid fibrils dissociation process is here suggested to be associated to a negative activation volume, supporting the notion that α-synuclein fibrils are in a high-volume and high-compressibility state and hinting at the presence of a hydration-mediated activated state from which dissociation occurs.


Assuntos
Amiloide/metabolismo , Doença de Parkinson/metabolismo , alfa-Sinucleína/metabolismo , Amiloide/química , Amiloide/genética , Humanos , Doença de Parkinson/genética , Mutação Puntual , Pressão , Espalhamento a Baixo Ângulo , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X , alfa-Sinucleína/química , alfa-Sinucleína/genética
14.
Biomed Microdevices ; 19(2): 41, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28484916

RESUMO

This study describes the preparation, characterization and in vitro release of monoolein aqueous dispersions (MAD) encapsulating quercetin (QT). As emulsifier, sodium cholate was employed at two different concentrations, namely 0.15% and 0.25% with respect to the total weight of the formulation. Cryogenic Transmission electron microscopy and X-ray analysis indicated that MAD015 are a mixture of vesicles and cubic structures, whilst MAD025 are mainly characterized by unilamellar vesicular structures. Photon correlation spectroscopy (PCS) and Sedimentation Field Flow Fractionation (SdFFF) showed a MAD size higher than 300 nm that over 100 days from analysis reduces up to 200 nm. In vitro Franz cell experiments showed that the two systems had a similar behaviour in the release of QT. Experiments on antioxidant activity of MAD containing QT demonstrated that their activity parallel with the content of encapsulated QT within the MAD formulations produced. Taken together these results allow us to conclude that MAD can be potentially proposed for the delivery of QT.


Assuntos
Antioxidantes/química , Portadores de Fármacos/química , Glicerídeos/química , Quercetina/química , Água/química , Antioxidantes/toxicidade , Linhagem Celular , Humanos , Cinética , Quercetina/toxicidade
15.
Biomed Microdevices ; 19(3): 44, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28526975

RESUMO

This study describes the potential of solid lipid nanoparticles and nanostructured lipid carriers as nano-formulations to administer to the central nervous system poorly water soluble drugs. Different neuroactive drugs, i.e. dimethylfumarate, retinyl palmitate, progesterone and the endocannabinoid hydrolysis inhibitor URB597 have been studied. Lipid nanoparticles constituted of tristearin or tristearin in association with gliceryl monoolein were produced. The nanoencapsulation strategy allowed to obtain biocompatible and non-toxic vehicles, able to increase the solubility of the considered neuroactive drugs. To improve URB597 targeting to the brain, stealth nanoparticles were produced modifying the SLN surface with polysorbate 80. A behavioural study was conducted in rats to test the ability of SLN containing URB597 given by intranasal administration to alter behaviours relevant to psychiatric disorders. URB597 maintained its activity after nanoencapsulation, suggesting the possibility to propose this kind of vehicle as alternative to unphysiological mixtures usually employed for animal and clinical studies.


Assuntos
Benzamidas/química , Carbamatos/química , Portadores de Fármacos/química , Lipídeos/química , Nanopartículas/química , Água/química , Animais , Benzamidas/metabolismo , Encéfalo/metabolismo , Carbamatos/metabolismo , Portadores de Fármacos/farmacocinética , Liberação Controlada de Fármacos , Glicerídeos/química , Cinética , Masculino , Tamanho da Partícula , Polissorbatos/química , Ratos , Ratos Wistar , Solubilidade , Distribuição Tecidual , Triglicerídeos/química
16.
Langmuir ; 32(3): 873-81, 2016 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-26710233

RESUMO

Structural properties and polymorphism of monoolein (MO) in aqueous solutions have been studied for a long time, and the final picture can be considered definite. The presence of bicontinuous phases and the ability to encapsulate hydrophilic, hydrophobic, and amphiphilic compounds, together with the capability to protect and slowly release the entrapped molecules, designated MO phases as good matrices for the sustained release of drugs. Because phase stability, loading efficiency, and bioavailability are strongly correlated, the interplay between MO phases and entrapped compounds is worthy of investigation. In this paper, low angle X-ray diffraction has been used to describe the effects of a model protein (the cytochrome-c) on the monoolein cubic phases as a function of both incubation time and protein concentration in the soaking solutions. Results show that the MO polymorphism is strongly modified by the protein, underlying the very large affinity of the cytochrome-c toward monoolein. However, the different phases have a different sensibility to cytochrome-c, as phase transitions occur when the protein amount exceeds some different critical values, probably related to the structure characteristics (2 cytochrome-c per unit cell at the Pn3m to Im3m cubic phase transition and 10-20 cytochrome-c per unit cell at the Im3m to P4332 cubic phase transition). Moreover, although equilibration times resulted to be quite long (more than 10 days), the fraction of cytochrome-c incorporated into the MO phases is very high (up to 20% v/v inside the P4332 cubic phase). Such results are intriguing: even if they may be specific to the cytochrome-c/MO case, the need of assessing the structural characteristics of lipid matrices before their use as drug delivery systems is evident.


Assuntos
Citocromos c/química , Sistemas de Liberação de Medicamentos , Glicerídeos/química , Cristalização , Cristalografia por Raios X , Composição de Medicamentos , Modelos Moleculares , Transição de Fase , Soluções , Temperatura , Água/química
17.
Biophys J ; 108(12): 2896-902, 2015 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-26083929

RESUMO

Septins comprise a family of proteins involved in a variety of cellular processes and related to several human pathologies. They are constituted by three structural domains: the N- and C-terminal domains, highly variable in length and composition, and the central domain, involved in the guanine nucleotide (GTP) binding. Thirteen different human septins are known to form heterogeneous complexes or homofilaments, which are stabilized by specific interactions between the different interfaces present in the domains. In this work, we have investigated by in-solution small-angle x-ray scattering the structural and thermodynamic properties of a human septin 3 construct, SEPT3-GC, which contains both of both interfaces (G and NC) responsible for septin-septin interactions. In order to shed light on the role of these interactions, small-angle x-ray scattering measurements were performed in a wide range of temperatures, from 2 up to 56°C, both with and without a nonhydrolysable form of GTP (GTPγS). The acquired data show a temperature-dependent coexistence of monomers, dimers, and higher-order aggregates that were analyzed using a global fitting approach, taking into account the crystallographic structure of the recently reported SEPT3 dimer, PDB:3SOP. As a result, the enthalpy, entropy, and heat capacity variations that control the dimer-monomer dissociation equilibrium in solution were derived and GTPγS was detected to increase the enthalpic stability of the dimeric species. Moreover, a temperature increase was observed to induce dissociation of SEPT3-GC dimers into monomers just preceding their reassembling into amyloid aggregates, as revealed by the Thioflavin-T fluorescence assays.


Assuntos
Simulação de Dinâmica Molecular , Septinas/química , Sequência de Aminoácidos , Guanosina Trifosfato/química , Guanosina Trifosfato/metabolismo , Humanos , Dados de Sequência Molecular , Ligação Proteica , Multimerização Proteica , Estrutura Terciária de Proteína , Espalhamento a Baixo Ângulo , Septinas/metabolismo , Difração de Raios X
18.
Biochim Biophys Acta ; 1830(10): 4974-80, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23850562

RESUMO

METHODS: Combining small-angle X-ray and neutron scattering measurements with inelastic neutron scattering experiments, we investigated the impact of high hydrostatic pressure on the structure and dynamics of ß-lactoglobulin (ßLG) in aqueous solution. BACKGROUND: ßLG is a relatively small protein, which is predominantly dimeric in physiological conditions, but dissociates to monomer below about pH3. RESULTS: High-pressure structural results show that the dimer-monomer equilibrium, as well as the protein-protein interactions, are only slightly perturbed by pressure, and ßLG unfolding is observed above a threshold value of 3000bar. In the same range of pressure, dynamical results put in evidence a slowing down of the protein dynamics in the picosecond timescale and a loss of rigidity of the ßLG structure. This dynamical behavior can be related to the onset of unfolding processes, probably promoted from water penetration in the hydrophobic cavity. GENERAL SIGNIFICANCE: Results suggest that density and compressibility of water molecules in contact with the protein are key parameters to regulate the protein flexibility.


Assuntos
Pressão Hidrostática , Lactoglobulinas/química , Conformação Proteica
19.
Colloids Surf B Biointerfaces ; 241: 114038, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38905813

RESUMO

Rhamnolipids are glycolipid surfactants composed by a hydrophilic head of either one (mono-RL) or two (di-RL) rhamnose moieties coupled to hydroxyaliphatic chains that can be of different lengths. In spite of their importance in different fields of applications, as bioremediation processes for instance, self-aggregation physico-chemical properties of RLs are not unique. This because a variety of aggregates morphologies (shape and size) can either exist or coexist in aqueous dispersion due to mono-RL:di-RL molar ratio, hydrophobic tails length, pH and the presence of co-surfactants and additives. Recently, a theorethical approach reported the self-assembling morphologies of either pure mono or di-RL in aqueous environment, predicting the formation of spherical to ellipsoidal micelles to worm-like and disk-like aggregates depending on RL concentration and fatty acid chain length. In order to add new information to those previously available, the present work investigated the self-assembling properties of mono-RL-C10-C10 and di-RL-C10-C10 separately in aqueous dispersion by small angle X-Ray scattering (SAXS). A novel approach was applied to the data analysis coupling the scattering length density profiles of the RLs chemical groups and Monte Carlo simulations. Such an approach allowed us to infer about the preferred mono-RL and di-RL conformations that fit better in the self-assembling morphologies. In this way, we show that mono-RL-C10-C10 self-assembles into lamella-like aggregates coexisting with 30 % of multi-lamella aggregates (circa of 5 closed stacked lamella) from a concentration ranging from 10 to 50 mM, with hydrophobic thickness of about 12 Å, a hydrated polar head thickness of 10 Å, and an area per glycolipid of 76 Å2. On the other hand, di-RL prefers to self-associate into flexible cylinder-like aggregates, from 70 mM to 110 mM concentration, with hydrophobic radius on the order of 7.5 Å, a hydrated polar shell of 21.5 Å, with hydropobic/polar interface of 110 Å2 per glycolipid. Interestingly, the parameters obtained from the best fitting to the experimental data associated to the volume fraction distribution of the chemical groups within the aggregates revealed that the hydrophobic chains are more disordered in mono-RL planar aggregates than in di-RL worm-like aggregates, as well as the hydration properties. Further, the addition of 100 mM NaCl in di-RL aqueous dispersion leads to the formation of longer worm-like aggregates. Taking together, this work opens a new avenue regarding characterization of biosurfactants self-assembling properties by using SAXS, also contributing to prepare more efficient biosurfactant dispersions depending on the desired applications in industrial sectors and bioremediation.

20.
Nat Commun ; 15(1): 4552, 2024 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-38811579

RESUMO

Perovskite solar cells promise to be part of the future portfolio of photovoltaic technologies, but their instability is slow down their commercialization. Major stability assessments have been recently achieved but reliable accelerated ageing tests on beyond small-area cells are still poor. Here, we report an industrial encapsulation process based on the lamination of highly viscoelastic semi-solid/highly viscous liquid adhesive atop the perovskite solar cells and modules. Our encapsulant reduces the thermomechanical stresses at the encapsulant/rear electrode interface. The addition of thermally conductive two-dimensional hexagonal boron nitride into the polymeric matrix improves the barrier and thermal management properties of the encapsulant. Without any edge sealant, encapsulated devices withstood multifaceted accelerated ageing tests, retaining >80% of their initial efficiency. Our encapsulation is applicable to the most established cell configurations (direct/inverted, mesoscopic/planar), even with temperature-sensitive materials, and extended to semi-transparent cells for building-integrated photovoltaics and Internet of Things systems.

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