Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 53
Filtrar
Más filtros

Bases de datos
Tipo del documento
País de afiliación
Intervalo de año de publicación
1.
Biomacromolecules ; 24(8): 3794-3805, 2023 08 14.
Artículo en Inglés | MEDLINE | ID: mdl-37535455

RESUMEN

Composite hydrogels composed of low-molecular-weight peptide self-assemblies and polysaccharides are gaining great interest as new types of biomaterials. Interactions between polysaccharides and peptide self-assemblies are well reported, but a molecular picture of their impact on the resulting material is still missing. Using the phosphorylated tripeptide precursor Fmoc-FFpY (Fmoc, fluorenylmethyloxycarbonyl; F, phenylalanine; Y, tyrosine; p, phosphate group), we investigated how hyaluronic acid (HA) influences the enzyme-assisted self-assembly of Fmoc-FFY generated in situ in the presence of alkaline phosphatase (AP). In the absence of HA, Fmoc-FFY peptides are known to self-assemble in nanometer thick and micrometer long fibers. The presence of HA leads to the spontaneous formation of bundles of several micrometers thickness. Using fluorescence recovery after photobleaching (FRAP), we find that in the bundles both (i) HA colocalizes with the peptide self-assemblies and (ii) its presence in the bundles is highly dynamic. The attractive interaction between negatively charged peptide fibers and negatively charged HA chains is explained through molecular dynamic simulations that show the existence of hydrogen bonds. Whereas the Fmoc-FFY peptide self-assembly itself is not affected by the presence of HA, this polysaccharide organizes the peptide nanofibers in a nematic phase visible by small-angle X-ray scattering (SAXS). The mean distance d between the nanofibers decreases by increasing the HA concentration c, but remains always larger than the diameter of the peptide nanofibers, indicating that they do not interact directly with each other. At a high enough HA concentration, the nematic organization transforms into an ordered 2D hexagonal columnar phase with a nanofiber distance d of 117 Å. Depletion interaction generated by the polysaccharides can explain the experimental power law variation d∼c-1/4 and is responsible for the bundle formation and organization. Such behavior is thus suggested for the first time on nano-objects using polymers partially adsorbing on self-assembled peptide nanofibers.


Asunto(s)
Hidrogeles , Nanofibras , Hidrogeles/química , Nanofibras/química , Ácido Hialurónico/química , Dispersión del Ángulo Pequeño , Difracción de Rayos X , Péptidos/química
2.
J Esthet Restor Dent ; 35(3): 517-524, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36453835

RESUMEN

OBJECTIVE: There is a growing interest in using pre-heated composites instead of dual-cured cements when luting indirect restorations. This study evaluated the film thickness obtained from two pre-heated composites and two resin cements, by two different operators. The influence of the materials and the level of expertise of the operator were analyzed. MATERIALS AND METHODS: Forty specimens of human dentin and composite discs were prepared and divided into four groups depending on the luting process. Each group was randomly equally divided to be handled by two operators with different levels of experience. Two of the initial four groups were luted using dual-cured cements and the two remaining groups using light-cured pre-heated composites. Specimen discs were cut after luting, and film thickness was measured using a Digital microscope. Data were analyzed using a 2-way ANOVA with the Holm-Sidak pairwise multiple comparison procedure (p < 0.05). RESULTS: Mean film thickness ranged from 156.16 ± 4.7 to 33.82 ± 0.7 µm. Significant differences (p < 0.001) were noticed between expert and novice results with pre-heated composites. CONCLUSION: Within the limits of this study, using pre-heated composites as a luting cement requires a better level of expertise to achieve a clinically acceptable film thickness. CLINICAL SIGNIFICANCE: Using pre-heated composites as luting agent for indirect restorations requires an experimented skill level to achieve a clinically recommended film thickness.


Asunto(s)
Resinas Compuestas , Cementos de Resina , Humanos , Cementos de Ionómero Vítreo
3.
Int J Comput Dent ; 23(4): 317-323, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33491927

RESUMEN

AIM: The aim of the present study was to compare six different methods of in vivo color matching: visual shade matching (3D-Master Linearguide shade guide) performed by 1) a novice practitioner, 2) an expert practitioner, 3) the new Rayplicker spectrometer, 4) the Trios III intraoral scanner, and 5) the Omnicam intraoral scanner compared with 6) the Easyshade V spectrophotometer, which was considered as the reference. MATERIALS AND METHODS: Color matching was performed using the 3D-Master references on the sound maxillary right central incisors of 40 subjects. The study first compared the number of colors found using each of the six methods. The references were then converted to the Commission Internationale de l'Eclairage (CIE) L*a*b* values, from which the difference ?E between either two methods ?was derived. Finally, the L* value was used to compare the luminosity measured by each of the six methods. RESULTS: The Rayplicker showed the smallest ?E compared with the Easyshade V. The expert found a closer color to the Easyshade V than did the novice, and both were closer to the Easyshade V than the two intraoral scanners. The intraoral scanners showed notable differences compared with the Easyshade V. The intraoral scanners also offered a reduced choice of colors and recorded the highest luminosities compared with the other methods. CONCLUSION: Within the limitations of this study, the color matching by the Rayplicker was closest to that of the Easyshade V. The good performance of this new device means that it is a challenging competitor for the Easyshade V. Finally, the new methods based on intraoral scanners were less reliable than the spectrophotometers and the visual shade matching.


Asunto(s)
Percepción de Color , Coloración de Prótesis , Color , Humanos , Incisivo , Espectrofotometría
4.
Langmuir ; 35(35): 11397-11405, 2019 09 03.
Artículo en Inglés | MEDLINE | ID: mdl-31387357

RESUMEN

Alginate/Fe3+ hydrogels were fabricated on hyaluronic acid (HA) and poly(allylamine hydrochloride) (PAH) multilayers to yield photoresponsive nanometer-scale hydrogels. Light irradiation of the resulting hydrogels induced the photoreduction of "hard" Fe3+ to "soft" Fe2+ cations, leading to changes in the mechanical properties of the hydrogels related to their cross-linking behavior. The buildup and the phototriggered response of the supported alginate hydrogels were followed in situ with a quartz crystal microbalance (QCM) using an open cell allowing light irradiation from an LED source on top of the hydrogel. The results were correlated to the release profiles of folic acid, employed herein as a drug model, obtained from light-irradiated supported iron alginate hydrogels.

5.
Langmuir ; 33(33): 8267-8276, 2017 08 22.
Artículo en Inglés | MEDLINE | ID: mdl-28749683

RESUMEN

Localized self-assembly allowing both spatial and temporal control over the assembly process is essential in many biological systems. This can be achieved through localized enzyme-assisted self-assembly (LEASA), also called enzyme-instructed self-assembly, where enzymes present on a substrate catalyze a reaction that transforms noninteracting species into self-assembling ones. Very few LEASA systems have been reported so far, and the control of the self-assembly process through the surface properties represents one essential step toward their use, for example, in artificial cell mimicry. Here, we describe a new type of LEASA system based on α-chymotrypsin adsorbed on a surface, which catalyzes the production of (KL)nOEt oligopeptides from a KLOEt (K: lysine; L: leucine; OEt ethyl ester) solution. When a critical concentration of the formed oligopeptides is reached near the surface, they self-assemble into ß-sheets resulting in a fibrillar network localized at the interface that can extend over several micrometers. One significant feature of this process is the existence of a lag time before the self-assembly process starts. We investigate, in particular, the effect of the α-chymotrypsin surface density and KLOEt concentration on the self-assembly kinetics. We find that the lag time can be finely tuned through the surface density in α-chymotrypsin and KLOEt concentration. For a given surface enzyme concentration, a critical KLOEt concentration exists below which no self-assembly takes place. This concentration increases when the surface density in enzyme decreases.


Asunto(s)
Péptidos/química , Cinética , Oligopéptidos , Propiedades de Superficie
6.
Langmuir ; 31(37): 10208-14, 2015 Sep 22.
Artículo en Inglés | MEDLINE | ID: mdl-26322650

RESUMEN

The development of new surface functionalization methods that are easy to use, versatile, and allow local deposition represents a real scientific challenge. Overcoming this challenge, we present here a one-pot process that consists in self-assembling, by electrochemistry on an electrode, films made of oppositely charged macromolecules. This method relies on a charge-shifting polyanion, dimethylmaleic-modified poly(allylamine) (PAHd), that undergoes hydrolysis at acidic pH, leading to an overall switching of its charge. When a mixture of the two polyanions, PAHd and poly(styrenesulfonate) (PSS), is placed in contact with an electrode, where the pH is decreased locally by electrochemistry, the transformation of PAHd into a polycation (PAH) leads to the continuous self-assembly of a nanometric PAH/PSS film by electrostatic interactions. The pH decrease is obtained by the electrochemical oxidation of hydroquinone, which produces protons locally over nanometric distances. Using a negatively charged enzyme, alkaline phosphatase (AP), instead of PSS, this one-pot process allows the creation of enzymatically active films. Under mild conditions, self-assembled PAH/AP films have an enzymatic activity which is adjustable simply by controlling the self-assembly time. The selective functionalization of microelectrode arrays by PAH/AP was achieved, opening the route toward miniaturized biosensors.


Asunto(s)
Electroquímica/métodos , Alilamina/química , Técnicas Biosensibles/métodos , Catálisis , Electrodos , Poliaminas/química , Polielectrolitos , Polímeros/química , Poliestirenos/química
7.
Angew Chem Int Ed Engl ; 54(35): 10198-201, 2015 Aug 24.
Artículo en Inglés | MEDLINE | ID: mdl-26179465

RESUMEN

The design and control of molecular systems that self-assemble spontaneously and exclusively at or near an interface represents a real scientific challenge. We present here a new concept, an active seed layer that allows to overcome this challenge. It is based on enzyme-assisted self-assembly. An enzyme, alkaline phosphatase, which transforms an original peptide, Fmoc-FFY(PO4 (2-) ), into an efficient gelation agent by dephosphorylation, is embedded in a polyelectrolyte multilayer and constitutes the "reaction motor". A seed layer composed of a polyelectrolyte covalently modified by anchoring hydrogelator peptides constitutes the top of the multilayer. This layer is the nucleation site for the Fmoc-FFY peptide self-assembly. When such a film is brought in contact with a Fmoc-FFY(PO4 (2-) ) solution, a nanofiber network starts to form almost instantaneously which extents up to several micrometers into the solution after several hours. We demonstrate that the active seed layer allows convenient control over the self-assembly kinetics and the geometric features of the fiber network simply by changing its peptide density.


Asunto(s)
Fosfatasa Alcalina/química , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Fragmentos de Péptidos/química , Tensoactivos/química , Fosfatasa Alcalina/metabolismo , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Microscopía Confocal , Simulación de Dinámica Molecular , Fragmentos de Péptidos/metabolismo , Espectroscopía Infrarroja por Transformada de Fourier , Tensoactivos/metabolismo
8.
Langmuir ; 30(22): 6479-88, 2014 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-24821198

RESUMEN

Step-by-step polymer film buildup processes lead to polymer coatings, e.g., polyelectrolyte multilayers, of various structures ranging from continuous smooth films to droplet like discontinuous coatings. Yet, the origin of these different behaviors depending upon the system is not yet known. This study is a first attempt to rationalize the evolution of the coating structure as a function of the strength of the interactions between the polymers constituting the film. We investigated the influence of the strength of noncovalent host-guest interactions between cyclodextrin (CD) and pyrene (Py), ferrocene (Fc) or adamantane (Ad) on the structure of neutral poly(N-hydroxypropylmethacrylamide) (PHPMA) multilayers films formed in a step-by-step manner. In solution, the strength of the inclusion complex (measured by log K where K is the complex association constant) is increasing in the order Py/ß-CD < Fc/ß-CD < Ad/ß-CD and can be further varied in the presence of different sodium salts at different ionic strengths. Depending upon this strength, the buildup process is limited to the formation of isolated aggregates for PHPMA-CD/PHPMA-Py, leading to smooth continuous films for PHPMA-CD/PHPMA-Fc and to droplet-like films, not entirely covering the substrate, for PHPMA-CD/PHPMA-Ad. To study the influence of the strength of the host-guest interactions on the film topography, PHPMA-CD/PHPMA-Fc films were built in the presence of different sodium salts at different ionic strengths. For low host-guest interactions, only isolated aggregates are formed on the substrate. As the strength of the host-guest interactions increases (increase of log K), the formed films go through a droplet-like structure, before becoming continuous but rough for stronger interactions. When the interaction strength is further increased, the roughness of the films decreases, leading to a smooth continuous film before becoming rough again at still higher interaction strength. Smooth continuous multilayers seem thus to be obtained for an optimal range of the interaction strength.


Asunto(s)
Membranas Artificiales , Polímeros/química , Adamantano/química , Ciclodextrinas/química , Compuestos Ferrosos/química , Metalocenos , Ácidos Polimetacrílicos/química , Pirenos/química
9.
Eur J Med Chem ; 268: 116224, 2024 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-38387338

RESUMEN

The emergence of bacterial strains resistant to antibiotics is a major issue in the medical field. Antimicrobial peptides are widely studied as they do not generate as much resistant bacterial strains as conventional antibiotics and present a broad range of activity. Among them, the homopolypeptide poly(l-arginine) presents promising antibacterial properties, especially in the perspective of its use in biomaterials. Linear poly(l-arginine) has been extensively studied but the impact of its 3D structure remains unknown. In this study, the antibacterial properties of newly synthesized branched poly(l-arginine) peptides, belonging to the family of multiple antigenic peptides, are evaluated. First, in vitro activities of the peptides shows that branched poly(l-arginine) is more efficient than linear poly(l-arginine) containing the same number of arginine residues. Surprisingly, peptides with more arms and more residues are not the most effective. To better understand these unexpected results, interactions between these peptides and the membranes of Gram positive and Gram negative bacteria are simulated thanks to molecular dynamic. It is observed that the bacterial membrane is more distorted by the branched structure than by the linear one and by peptides containing smaller arms. This mechanism of action is in full agreement with in vitro results and suggest that our simulations form a robust model to evaluate peptide efficiency towards pathogenic bacteria.


Asunto(s)
Antibacterianos , Simulación de Dinámica Molecular , Péptidos , Antibacterianos/farmacología , Antibacterianos/química , Péptidos Catiónicos Antimicrobianos/farmacología , Péptidos Catiónicos Antimicrobianos/química , Bacterias Gramnegativas , Bacterias Grampositivas , Arginina/farmacología , Bacterias , Pruebas de Sensibilidad Microbiana
10.
Langmuir ; 29(24): 7488-98, 2013 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-23346932

RESUMEN

The identification and quantification of biomarkers or proteins is a real challenge in allowing the early detection of diseases. The functionalization of the biosensor surface has to be properly designed to prevent nonspecific interactions and to detect the biomolecule of interest specifically. A multilayered nanoarchitecture, based on polyelectrolyte multilayers (PEM) and the sequential immobilization of streptavidin and a biotinylated antibody, was elaborated as a promising platform for the label-free sensing of targeted proteins. We choose ovalbumin as an example. Thanks to the versatility of PEM films, the platform was built on two types of sensor surface and was evaluated using both optical- and viscoelastic-based techniques, namely, optical waveguide lightmode spectroscopy and the quartz crystal microbalance, respectively. A library of biotinylated poly(acrylic acids) (PAAs) was synthesized by grafting biotin moieties at different grafting ratios (GR). The biotin moieties were linked to the PAA chains through ethylene oxide (EO) spacers of different lengths. The adsorption of the PAA-EOn-biotin (GR) layer on a PEM precursor film allows tuning the surface density in biotin and thus the streptavidin adsorption mainly through the grafting ratio. The nonspecific adsorption of serum was reduced and even suppressed depending on the length of the EO arms. We showed that to obtain an antifouling polyelectrolyte the grafting of EO9 or EO19 chains at 25% in GR is sufficient. Thus, the spacer has a dual role: ensuring the antifouling property and allowing the accessibility of biotin moieties. Finally, an optimized platform based on the PAA-EO9-biotin (25%)/streptavidin/biotinylated-antibody architecture was built and demonstrated promising performance as interface architecture for bioaffinity sensing of a targeted protein, in our case, ovalbumin.


Asunto(s)
Técnicas Biosensibles , Óxido de Etileno/química , Nanoestructuras , Proteínas/química , Adsorción
11.
Langmuir ; 29(34): 10776-84, 2013 Aug 27.
Artículo en Inglés | MEDLINE | ID: mdl-23895332

RESUMEN

The design of films using a one-pot process has recently attracted increasing interest in the field of polymer thin film formation. Herein we describe the preparation of one-pot supramolecular polyrotaxane (PRX) films using the morphogen-driven self-construction process. This one-pot buildup strategy where the film growth is triggered by the electrochemical formation and diffusion of a catalyst in close vicinity of the substrate has recently been introduced by our group. A one-pot mixture was used that contained (i) poly(acrylic acid) (PAA) functionalized by azide groups grafted on the polymer chain through oligo(ethylene glycol) (EG) arms, leading to PAA-EG13-N3, (ii) cyclodextrins (α and ß CD), as macrocycles that can be threaded along EG arms, (iii) alkyne-functionalized stoppers (ferrocene or adamantane), to cap the PRX assembly by click chemistry, and (iv) copper sulfate. The one-pot mixture solution was brought into contact with a gold electrode. Cu(I), the morphogen, was generated electrochemically from Cu(II) at the electrode/one-pot solution interface. This electrotriggered click reaction leads to the capping of polypseudorotaxane yielding to PRXs. The PRXs can self-assemble through lateral supramolecular interactions to form aggregates and ensure the cohesion of the film. The film buildup was investigated using different types of CD and alkyne functionalized stoppers. Supramolecular PRX aggregates were characterized by X-ray diffraction measurements. The film topographies were imaged by atomic force microscopy. The influence of the concentration in CD and the presence of a competitor were studied as well. The stability of the resulting film was tested in contact with 8 M urea and during the electrochemical oxidation of ferrocene.


Asunto(s)
Ciclodextrinas/química , Electroquímica/métodos , Poloxámero/química , Rotaxanos/química , Química Clic , Electrodos , Microscopía de Fuerza Atómica , Estructura Molecular
12.
Langmuir ; 29(47): 14536-44, 2013 Nov 26.
Artículo en Inglés | MEDLINE | ID: mdl-24171660

RESUMEN

Simultaneous spraying of polyelectrolytes and small multicharged molecules of opposite charges onto a vertical substrate leads to continuous buildups of organic films. Here, we investigate the rules governing the buildup of two such systems: poly(allylamine hydrochloride)/sodium citrate (PAH/citrate) and PAH/sulfated α-cyclodextrin (PAH/CD-S). Special attention is paid to the film growth rate as a function of the spraying rate ratio of the two constituents. This parameter was varied by increasing the spraying rate of one of the constituents while maintaining constant that of the other. For PAH/CD-S systems, whatever the constituent (PAH or CD-S) whose spraying rate was kept fixed, the film growth rate first increases and passes through a maximum before decreasing when the spraying rate of the other constituent is increased. For PAH/citrate, the film growth rate reaches a plateau value when the spraying rate of citrate is increased while that of PAH is maintained constant, whereas when the spraying rate of citrate is maintained constant and that of PAH is increased, a behavior similar to that of PAH/CD-S is observed. The composition of PAH/CD-S sprayed films determined by X-ray photoelectron spectroscopy is independent of the spraying rate ratio of the two constituents and corresponds to one allylamine for one sulfate group. For PAH/citrate, by increasing the PAH/citrate spraying rate ratio, the carboxylic/nitrogen ratio in the film increases and tends to 1. There is thus always a deficit of carboxylic groups (COO(-) + COOH) with respect to amines (NH2 + NH3(+)). Yet, the ratio (COO(-)/NH3(+)) is always close to 1, ensuring exact charge compensation. The film morphology determined by atomic force microscopy is granular for PAH/CD-S and is smooth and liquid-like for PAH/citrate. A model based on strong (respectively weak) interactions between PAH and CD-S (respectively citrate) is proposed to explain these features.

13.
J Colloid Interface Sci ; 633: 876-885, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36495809

RESUMEN

Enzyme-assisted self-assembly confined within host materials leads to Liesegang-like spatial structuration when precursor peptides are diffusing through an enzyme-functionalized hydrogel. It is shown here that playing on peptide and enzyme concentrations results in a transition from continuous self-assembled peptide areas to individual microglobules. Their morphology, location, size and buildup mechanism are described. Additionally, it is also found that the enzymes adsorb onto the peptide self-assemblies leading to co-localization of peptide self-assembled microglobules and enzymes. Finally, we find that large microglobules grow at the expense of smaller ones present in their vicinity in a kind of Ostwald ripening process, illustrating the dynamic nature of the peptide self-assembly process within host hydrogels.


Asunto(s)
Hidrogeles , Péptidos , Difusión
14.
J Am Chem Soc ; 134(1): 83-6, 2012 Jan 11.
Artículo en Inglés | MEDLINE | ID: mdl-22188330

RESUMEN

Cell adhesion processes take place through mechanotransduction mechanisms where stretching of proteins results in biological responses. In this work, we present the first cyto-mechanoresponsive surface that mimics such behavior by becoming cell-adhesive through exhibition of arginine-glycine-aspartic acid (RGD) adhesion peptides under stretching. This mechanoresponsive surface is based on polyelectrolyte multilayer films built on a silicone sheet and where RGD-grafted polyelectrolytes are embedded under antifouling phosphorylcholine-grafted polyelectrolytes. The stretching of this film induces an increase in fibroblast cell viability and adhesion.


Asunto(s)
Mecanotransducción Celular , Polímeros/química , Biomimética , Adhesión Celular , Electrólitos/química , Fibroblastos/citología , Oligopéptidos/química , Propiedades de Superficie
15.
J Cell Sci ; 123(Pt 1): 29-39, 2010 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-20016064

RESUMEN

Actin cytoskeleton forms a physical connection between the extracellular matrix, adhesion complexes and nuclear architecture. Because tissue stiffness plays key roles in adhesion and cytoskeletal organization, an important open question concerns the influence of substrate elasticity on replication and transcription. To answer this major question, polyelectrolyte multilayer films were used as substrate models with apparent elastic moduli ranging from 0 to 500 kPa. The sequential relationship between Rac1, vinculin adhesion assembly, and replication becomes efficient at above 200 kPa because activation of Rac1 leads to vinculin assembly, actin fiber formation and, subsequently, to initiation of replication. An optimal window of elasticity (200 kPa) is required for activation of focal adhesion kinase through auto-phosphorylation of tyrosine 397. Transcription, including nuclear recruitment of heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1), occurred above 50 kPa. Actin fiber and focal adhesion signaling are not required for transcription. Above 50 kPa, transcription was correlated with alphav-integrin engagement together with histone H3 hyperacetylation and chromatin decondensation, allowing little cell spreading. By contrast, soft substrate (below 50 kPa) promoted morphological changes characteristic of apoptosis, including cell rounding, nucleus condensation, loss of focal adhesions and exposure of phosphatidylserine at the outer cell surface. On the basis of our data, we propose a selective and uncoupled contribution from the substrate elasticity to the regulation of replication and transcription activities for an epithelial cell model.


Asunto(s)
Células Epiteliales/fisiología , Adhesiones Focales/metabolismo , Proteína de Unión al GTP rac1/metabolismo , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Animales , Apoptosis , Adhesión Celular/fisiología , Línea Celular , Proliferación Celular , Ensamble y Desensamble de Cromatina , Elasticidad , Células Epiteliales/patología , Adhesiones Focales/química , Histonas/metabolismo , Cadenas alfa de Integrinas/metabolismo , Películas Cinematográficas/estadística & datos numéricos , Ratas , Activación Transcripcional , Vinculina/metabolismo
16.
Langmuir ; 28(38): 13550-4, 2012 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-22957730

RESUMEN

The design of stimuli-responsive polymer assemblies for the controlled release of bioactive molecules has raised considerable interest these two last decades. Herein, we report the design of mechanically responsive drug-releasing films made of polyelectrolyte multilayers. A layer-by-layer (LbL) reservoir containing biodegradable polyelectrolytes is capped with a mechanosensitive LbL barrier and responds to stretching by a total enzymatic degradation of the film. This strategy is successfully applied for the release in solution of an anticancer drug initially loaded within the architecture.


Asunto(s)
Antineoplásicos Fitogénicos/metabolismo , Membranas Artificiales , Paclitaxel/metabolismo , Polímeros/metabolismo , Antineoplásicos Fitogénicos/química , Electrólitos/química , Electrólitos/metabolismo , Conformación Molecular , Paclitaxel/química , Polímeros/química , Estrés Mecánico
17.
Biomacromolecules ; 13(7): 2128-35, 2012 Jul 09.
Artículo en Inglés | MEDLINE | ID: mdl-22662909

RESUMEN

Surface functionalization plays an important role in the design of biomedical implants, especially when layer forming cells, such as endothelial or epithelial cells, are needed. In this study, we define a novel nanoscale surface coating composed of collagen/alginate polyelectrolyte multilayers and cross-linked for stability with genipin. This buildup follows an exponential growth regime versus the number of deposition cycles with a distinct nanofibrillar structure that is not damaged by the cross-linking step. Stability and cell compatibility of the cross-linked coatings were studied with human umbilical vein endothelial cells. The surface coating can be covered by a monolayer of vascular endothelial cells within 5 days. Genipin cross-linking renders the surface more suitable for cell attachment and proliferation compared to glutaraldehyde (more conventional cross-linker) cross-linked surfaces, where cell clumps in dispersed areas were observed. In summary, it is possible with the defined system to build fibrillar structures with a nanoscale control of film thickness, which would be useful for in vivo applications such as inner lining of lumens for vascular and tracheal implants.


Asunto(s)
Materiales Biocompatibles/síntesis química , Reactivos de Enlaces Cruzados/química , Colágenos Fibrilares/química , Iridoides/química , Alginatos/química , Materiales Biocompatibles/química , Adhesión Celular , Proliferación Celular , Forma de la Célula , Células Cultivadas , Ácido Glucurónico/química , Glutaral/química , Ácidos Hexurónicos/química , Células Endoteliales de la Vena Umbilical Humana/fisiología , Humanos , Concentración de Iones de Hidrógeno , Microscopía de Fuerza Atómica , Nanofibras/química , Espectroscopía Infrarroja por Transformada de Fourier , Propiedades de Superficie , Andamios del Tejido/química
18.
J Colloid Interface Sci ; 620: 234-241, 2022 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-35428005

RESUMEN

Reaction-diffusion (RD) processes are responsible for surface and in-depth micropatterning in inanimate and living matter. Here we show that enzyme-assisted self-assembly (EASA) of peptides is a valuable tool to functionnalize host gels. By using a phosphatase distributed in a host hydrogel, the diffusion of phosphorylated peptides from a liquid/host gel interface leads to the spontaneous formation of a pattern of dephosphorylated peptide self-assembly presenting at least two self-assembly maxima. Variation of enzyme and peptide concentrations change the pattern characteristics. When a peptide drop is deposited on a phosphatase functionalized gel, a self-assembly pattern is also formed both along the gel-solution interface and perpendicular to the interface. This self-assembly pattern induces a local change of the gel mechanical properties measured by nanoindentation. Its appearance relies on the formation of self-assembled structures by nucleation and growth processes which are static in the hydrogel. This process presents great similarities with the Liesegang pattern formation and must be taken into account for the functionalization of hydrogels by EASA. A mechanism based on RD is proposed leading to an effective mathematical model accounting for the pattern formation. This work highlights EASA as a tool to design organic Liesegang-like microstructured materials with potential applications in biomaterials and artificial living systems design.


Asunto(s)
Hidrogeles , Péptidos , Materiales Biocompatibles , Difusión , Hidrogeles/química , Péptidos/química , Monoéster Fosfórico Hidrolasas
19.
J Funct Biomater ; 13(4)2022 Nov 11.
Artículo en Inglés | MEDLINE | ID: mdl-36412878

RESUMEN

The surface stiffness of the microenvironment is a mechanical signal regulating biofilm growth without the risks associated with the use of bioactive agents. However, the mechanisms determining the expansion or prevention of biofilm growth on soft and stiff substrates are largely unknown. To answer this question, we used PDMS (polydimethylsiloxane, 9-574 kPa) and HA (hyaluronic acid gels, 44 Pa-2 kPa) differing in their hydration. We showed that the softest HA inhibited Escherichia coli biofilm growth, while the stiffest PDMS activated it. The bacterial mechanical environment significantly regulated the MscS mechanosensitive channel in higher abundance on the least colonized HA-44Pa, while Type-1 pili (FimA) showed regulation in higher abundance on the most colonized PDMS-9kPa. Type-1 pili regulated the free motion (the capacity of bacteria to move far from their initial position) necessary for biofilm growth independent of the substrate surface stiffness. In contrast, the total length travelled by the bacteria (diffusion coefficient) varied positively with the surface stiffness but not with the biofilm growth. The softest, hydrated HA, the least colonized surface, revealed the least diffusive and the least free-moving bacteria. Finally, this shows that customizing the surface elasticity and hydration, together, is an efficient means of affecting the bacteria's mobility and attachment to the surface and thus designing biomedical surfaces to prevent biofilm growth.

20.
Sci Rep ; 11(1): 18702, 2021 09 21.
Artículo en Inglés | MEDLINE | ID: mdl-34548560

RESUMEN

Layer-by-layer (LbL) deposition method of polyelectrolytes is a versatile way of developing functional nanoscale coatings. Even though the mechanisms of LbL film development are well-established, currently there are no predictive models that can link film components with their final properties. The current health crisis has shown the importance of accelerated development of biomedical solutions such as antiviral coatings, and the implementation of machine learning methodologies for coating development can enable achieving this. In this work, using literature data and newly generated experimental results, we first analyzed the relative impact of 23 coating parameters on the coating thickness. Next, a predictive model has been developed using aforementioned parameters and molecular descriptors of polymers from the DeepChem library. Model performance was limited because of insufficient number of data points in the training set, due to the scarce availability of data in the literature. Despite this limitation, we demonstrate, for the first time, utilization of machine learning for prediction of LbL coating properties. It can decrease the time necessary to obtain functional coating with desired properties, as well as decrease experimental costs and enable the fast first response to crisis situations (such as pandemics) where coatings can positively contribute. Besides coating thickness, which was selected as an output value in this study, machine learning approach can be potentially used to predict functional properties of multilayer coatings, e.g. biocompatibility, cell adhesive, antibacterial, antiviral or anti-inflammatory properties.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA