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Supramolecular hydrogels based on peptide amphiphiles (PAs) are promising materials for tissue engineering and model extracellular matrixes for biological studies. While PA hydrogels are conventionally formed via electrostatic screening, new hydrogelation mechanisms might help to improve the design and functionality of these materials. Here, we present a host-guest-mediated PA hydrogelation method that relies on the formation of a host-guest homoternary complex with cucurbit[8]uril (

Aqueous systems composed of low molecular-weight species (LMWS) and water-soluble polymers (WSP) present important technological applications. Therefore, continuous advances on characterization techniques are crucial to gain a better understanding on how these systems interact and subsequently further modulate their properties by tuning their preparation process. For that matter, this work aims at comparing a developing characterization tool, diafiltration (DF), with a well-established method for studying LMWS/macromolecule interactions, isothermal titration calorimetry (ITC). Chlorpheniramine maleate (CPM) and poly(sodium 4-styrenesulfonate) (PSS) are used as a model aqueous LMWS/WSP system. The comparison is based on the CPM fraction bound to PSS measured by both methods. The values obtained are (0.89 ± 0.00) and (0.88 ± 0.05) for DF and ITC, respectively. The similarity between these values is noteworthy considering the dissimilarity of the process on which both techniques are based (filtration and heat exchange). This work constitutes a first step on setting DF and ITC as complementary and supporting techniques. Additional implications from these results are further discussed Los sistemas acuosos compuestos por especies de bajo peso molecular (LMWS) y polímeros solubles en agua (WSP) presentan importantes aplicaciones tecnológicas. Por lo tanto, los avances continuos en las técnicas de caracterización son cruciales para comprender mejor cómo interactúan estos sistemas y, posteriormente, modular aún más sus propiedades ajustando su proceso de preparación. De hecho, este trabajo tiene como objetivo comparar una herramienta de caracterización en desarrollo, la diafiltración (DF), con un método bien establecido para estudiar las interacciones LMWS / macromoléculas, la calorimetría de titulación isotérmica (ITC). El maleato de clorfeniramina (CPM) y el poli (4-estirenosulfonato de sodio) (PSS) se utilizan como un sistema acuoso modelo LMWS / WSP. La comparación se basa en la fracción de CPM unida a PSS medida por ambos métodos. Los valores obtenidos son (0,89 ± 0,00) y (0,88 ± 0,05) para DF e ITC, respectivamente. La similitud entre estos valores es destacable considerando la disimilitud del proceso en el que se basan ambas técnicas (filtración e intercambio de calor). Este trabajo constituye un primer paso para establecer el DF y las TIC como técnicas complementarias y de apoyo. Se discuten más a fondo las implicaciones adicionales de estos resultados. Universidad Nacional, Costa Rica Centro Nacional de Alta Tecnología, Costa Rica University of Groningen, Netherlands Queen Mary University of London, United Kingdom Universidad Austral de Chile, Chile Escuela de Química

Supramolecular polymer-based biomaterials play a significant role in current biomedical research. In particular, peptide amphiphiles (PAs) represent a promising material platform for biomedical applications given their modular assembly, tunability, and capacity to render materials with structural and molecular precision. However, the possibility to provide dynamic cues within PA-based materials would increase the capacity to modulate their mechanical and physical properties and, consequently, enhance their functionality and broader use. In this study, we report on the synthesis of a cationic PA pair bearing complementary adamantane and β-cyclodextrin host-guest cues and their capacity to be further incorporated into self-assembled nanostructures. We demonstrate the possibility of these recognition motifs to selectively bind, enabling noncovalent cross-linking between PA nanofibers and endowing the resulting supramolecular hydrogels with enhanced mechanical properties, including stiffness and resistance to degradation, while retaining in vitro biocompatibility. The incorporation of the host-guest PA pairs in the resulting hydrogels allowed not only for macroscopic mechanical control from the molecular scale, but also for the possibility to engineer further spatiotemporal dynamic properties, opening opportunities for broader potential applications of PA-based materials.

In this work, we describe the physicochemical characterization of amphiphilic glycopolymers synthesized via copper(0)-mediated reversible-deactivation radical polymerization (Cu-RDRP). Depending on the chemical composition of the polymer, these glycopolymers are able to form multi-chain or single-chain polymeric nanoparticles. The folding of these polymers is first of all driven by the amphiphilicity of the glycopolymers and furthermore by the supramolecular formation of helical supramolecular stacks of benzene-1,3,5-tricarboxamides (BTAs) stabilized by threefold hydrogen bonding. The obtained polymeric nanoparticles were subsequently evaluated for their lectin-binding affinity toward a series of mannose- and galactose-binding lectins via surface plasmon resonance. We found that addition of 2-ethylhexyl acrylate to the polymer composition results in compact particles, which translates to a reduction in binding affinity, whereas with the addition of BTAs, the relation between the nature of the particle and the binding ability system becomes more unpredictable.

A key feature in biomaterial design is the incorporation of bioactive signals into artificial constructs to stimulate tissue regeneration. Most currently used hydrogel cell culture systems depend on the covalent attachment of extracellular matrix (ECM)-derived peptides to either macromolecular units or smaller self-assembling building blocks, thereby restricting biosignal presentation and adaptability. However, new ways to rationally incorporate adhesion epitopes through noncovalent interactions would offer opportunities to better recreate the dynamic and reversible nature of the native ECM. Here, we report on a noncovalent epitope presentation approach mediated by host-guest interactions. Using peptide amphiphile hydrogels, we demonstrate that the adamantane/β-cyclodextrin pair can be used to anchor RGDS cell adhesion signals onto self-assembled hydrogels via host-guest interactions. We evaluate hydrogel morphological and rheological properties as well as fibroblast attachment, organization, and spreading when cultured atop these scaffolds. This host-guest-mediated epitope display might lead to new self-assembling hydrogels for improved cell culture applications in fields such as tissue engineering and regenerative medicine.

Se seleccionó la licencia Creative Commons para este envío. El documento trae lo siguiente: © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. (En caso de duda consultar a Meilyn Garro). Background: Collagen, the most abundant protein in the animal kingdom, represents a promising biomaterial for regenerative medicine applications due to its structural diversity and self-assembling complexity. Despite collagen’s widely known structural and functional features, the thermodynamics behind its fibrillogenic self-assembling process is still to be fully understood. In this work we report on a series of spectroscopic, mechanical, morphological and thermodynamic characterizations of high purity type I collagen (with a D-pattern of 65 nm) extracted from Wistar Hannover rat tail. Our herein reported results can be of help to elucidate differences in selfassembly states of proteins using ITC to improve the design of energy responsive and dynamic materials for applications in tissue engineering and regenerative medicine. Methods: Herein we report the systematic study on the self-assembling fibrillogenesis mechanism of type I collagen, we provide morphological and thermodynamic evidence associated to different self-assembly events using ITC titrations. We provide thorough characterization of the effect of pH, effect of salts and protein conformation on self-assembled collagen samples via several complementary biophysical techniques, including circular dichroism (CD), Fourier Transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), atomic force microscopy (AFM), scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). Results: Emphasis was made on the use of isothermal titration calorimetry (ITC) for the thermodynamic monitoring of fibrillogenesis stages of the protein. An overall self-assembly enthalpy value of 3.27 ± 0.85 J/mol was found. Different stages of the self-assembly mechanism were identified, initial stages take place at pH values lower than the protein isoelectric point (pI), however, higher energy release events were recorded at collagen’s pI. Denatured collagen employed as a control exhibited higher energy absorption at its pI, suggesting different energy exchange mechanisms as a consequence of different aggregation routes Antecedentes: el colágeno, la proteína más abundante en el reino animal, representa un biomaterial prometedor para aplicaciones de medicina regenerativa debido a su diversidad estructural y complejidad de autoensamblaje. A pesar de las características estructurales y funcionales ampliamente conocidas del colágeno, la termodinámica detrás de su proceso de autoensamblaje fibrilogénico aún debe entenderse completamente. En este trabajo informamos sobre una serie de caracterizaciones espectroscópicas, mecánicas, morfológicas y termodinámicas de colágeno tipo I de alta pureza (con un patrón D de 65 nm) extraído de la cola de rata Wistar Hannover. Nuestros resultados aquí reportados pueden ayudar a dilucidar las diferencias en los estados de autoensamblaje de proteínas usando ITC para mejorar el diseño de materiales dinámicos y sensibles a la energía para aplicaciones en ingeniería de tejidos y medicina regenerativa. Métodos: A continuación presentamos el estudio sistemático sobre el mecanismo de fibrilogénesis autoensamblante del colágeno tipo I, aportamos evidencia morfológica y termodinámica asociada a diferentes eventos de autoensamblaje mediante titulaciones ITC. Proporcionamos una caracterización completa del efecto del pH, el efecto de las sales y la conformación de proteínas en muestras de colágeno autoensambladas a través de varias técnicas biofísicas complementarias, que incluyen dicroísmo circular (CD), espectroscopía infrarroja por transformada de Fourier (FTIR), calorimetría diferencial de barrido (DSC), microscopía de fuerza atómica (AFM), microscopía electrónica de barrido (SEM), análisis térmico mecánico dinámico (DMTA) y análisis termogravimétrico (TGA). Resultados: Se hizo énfasis en el uso de calorimetría de titulación isotérmica (ITC) para el monitoreo termodinámico de las etapas de fibrilogénesis de la proteína. Se encontró un valor de entalpía de autoensamblaje general de 3,27 ± 0,85 J / mol. Se identificaron diferentes etapas del mecanismo de autoensamblaje, las etapas iniciales tienen lugar a valores de pH más bajos que el punto isoeléctrico de la proteína (pI), sin embargo, se registraron eventos de liberación de energía más altos en el pI del colágeno. El colágeno desnaturalizado empleado como control exhibió una mayor absorción de energía en su pI, lo que sugiere diferentes mecanismos de intercambio de energía como consecuencia de diferentes rutas de agregación. Instituto Tecnológico de Costa Rica, Costa Rica Universidad SEK Chile, Chile Universidad de Costa Rica, Costa Rica Centro Nacional de Alta Tecnología, Costa Rica Universidad Nacional, Costa Rica Escuela de Química

Bioengineered matrices from self-assembling peptides and extracellular matrix proteins can model the tumor microenvironment., Bioengineered three-dimensional (3D) matrices expand our experimental repertoire to study tumor growth and progression in a biologically relevant, yet controlled, manner. Here, we used peptide amphiphiles (PAs) to coassemble with and organize extracellular matrix (ECM) proteins producing tunable 3D models of the tumor microenvironment. The matrix was designed to mimic physical and biomolecular features of tumors present in patients. We included specific epitopes, PA nanofibers, and ECM macromolecules for the 3D culture of human ovarian cancer, endothelial, and mesenchymal stem cells. The multicellular constructs supported the formation of tumor spheroids with extensive F-actin networks surrounding the spheroids, enabling cell-cell communication, and comparative cell-matrix interactions and encapsulation response to those observed in Matrigel. We conducted a proof-of-concept study with clinically used chemotherapeutics to validate the functionality of the multicellular constructs. Our study demonstrates that peptide-protein coassembling matrices serve as a defined model of the multicellular tumor microenvironment of primary ovarian tumors.

Biomolecule derivatives are transversally used in nanotechnology. Deciphering their aggregation behavior is a crucial issue for the rational design of functional materials. To this end, it is necessary to build libraries of selectively functionalized analogues and infer general rules. In this work we enrich the highly applicative oriented collection of steroid derivatives, by reporting a rare example of C-12 selectively modified bile salt. While nature often exploits such position to encode functions, it is unusual and not trivial to prepare similar analogues in the laboratory. The introduction of a tert-butyl phenyl residue at C-12 provided a molecule with a self-assembly that remarkably switched from rigid pole-like structures to twisted ribbons at a biologically relevant critical temperature (∼25 °C). The system was characterized by microscopy and spectroscopy techniques and compared with the C-3 functionalized analogue. The twisted ribbons generate samples with a gel texture and a viscoelastic response. The parallel analysis of the two systems suggested that the observed thermoresponsive self-assemblies occur at similar critical temperatures and are probably dictated by the nature of the substituent, but involve aggregates with different structures depending on position and orientation of the substituent. This study highlights the self-assembly properties of two appealing thermoresponsive systems. Moreover, it adds fundamental insights hereto missing in the investigations of the relation between self-assembly and structure of synthetic steroids, which are valuable for the rational design of steroidal amphiphiles.

Self-assembled structures formed by mixtures of cationic and anionic surfactants are interesting tools for applications requiring interactions with charged particles and molecules. Nevertheless, they present instability close to the equimolar composition and poor morphological versatility, which is generally restricted to vesicles and micelles. Against this general trend, we report on bile salt derivative based catanionic mixtures assembling in tubules and lamellae depending on the mixture composition. Electrophoretic mobility measurements prove that the composition also dictates their superficial charge, which can be tuned from negative to positive by increasing the positively charged surfactant fraction in the mixtures. The study of the catanionic aggregates was conducted by means of microscopy and spectroscopy techniques and compared to the self-assembly behaviors of the individual building blocks. This study broadens the so far small array of bile salt derivative catanionic systems, confirming their distinctive behavior in the spectrum of catanionic mixtures.

Despite the vast volume of literature regarding the interaction between carbon nanotubes and surfactants, the effect of the covalent attachment of an amphiphilic surfactant based on a biomimetic approach to multiwalled carbon nanotubes (MWCNT) has not been explored. In this report, the functionalization of the MWCNT surface with cholic acid by a chemical route is described. A three-step MWCNT chemical modification route was carried out and the properties of the intermediate and final materials were evaluated employing X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and zeta potential measurements. After functionalization, the MWCNT showed a facial bio-amphiphilic behavior; improving the dispersion stability as compared to commercial and oxidized MWCNT. The resulting material preserved the pristine multi-walled structure and originated surprisingly stable dispersions in aqueous and organic polar and low-polarity solvents.

Nanomedicine has allowed for emerging advances in imaging, diagnostics and therapeutics. Regenerative Medicine has taken advantage of a number of nanomaterials for reparation of diseased or damaged tissues in the nervous system involved in memory, cognition and movement. Electrical, thermal, mechanical and biocompatibility aspects of carbon-based nanomaterials (nanotubes, graphene, fullerenes and their derivatives) make them suitable candidates to drive nerve tissue repair and stimulation. This review article focuses on recent advances on the use of carbon nanotube (CNT)-based technologies on nerve tissue engineering; outlining how neurons interact with the nanomaterials interface for promoting neuronal differentiation, growth and network reconstruction for their possible use in therapies of neurodegenerative pathologies and spinal cord injuries.

Human body is an archetypal of multicomponent hydrogels, precisely fabricated by nature’s intelligent use of supramolecular self-assembly of various building blocks. Therefore, in order to regenerate impaired tissues, the use of multicomponent self-assembly is fast becoming an attractive strategy for developing bio-relevant hydrogels that recapitulate the complexity and multifunctionality of native tissues. As such, in this chapter we focus on the concept of multicomponent self-assembly as a biomimetic approach for developing hydrogel biomaterials for biomedical applications using various mixtures of building blocks of different molecular sizes (small-small molecules, small molecules-macromolecule, and macromolecules) and sources (amino acids, peptides, saccharides, and nucleobases).

Vesículas a base de L-α-fosfatidilcolina (PC) y mezclas de PC/fosfogliceroles fueron caracterizadas por medio de dispersión de luz dinámica (DLS), microscopía electrónica de barrido-criogénico (Cryo-SEM) y calorimetría de titulación isotérmica (ITC). La incorporación de fosfogliceroles en la formulación de vesículas a base PC disminuyó el tamaño y la polidispersidad de las partículas, debido a un mayor empaquetamiento de las cadenas alifáticas por medio de interacciones de van der Waals. Además, resultó en una disminución significativa de la carga superficial de -75 mV comparada con el potencial Z (ξ) de las vesículas a base de PC. Ambos sistemas fueron modificados usando un polielectrolito catiónico (quitosano) de un peso molecular de 865 kDa y con un grado de desacetilación de 77 %. La naturaleza aniónica de la vesícula fosfolipídica resultó en una efectiva interacción con el polielectrolito catiónico mediante fuerzas del tipo electrostática, la cual fue determinada por medio de ITC. Los resultados fueron complementados mediante la determinación de potencial Z de los sistemas modificados, lo cual demostró que no es necesaria una inversión completa de la carga inicial de la superficie de la vesícula para asegurar el recubrimiento de esta. La adición de concentraciones de quitosano mayores a 0,1 mg/mL condujo a la agregación de las vesículas, lo cual fue demostrado mediante Cryo-SEM y DLS. Este efecto fue más significativo para el sistema basado en dimiristoilfosfoglicerol sal de sodio y quitosano, debido a la fuerte atracción electrostática. L-α-phosphatidylcholine (PC) and PC/phosphoglycerol based-vesicles were characterized by Dynamic Light Scattering (DLS), Cryo-Scanning Electron Microscopy (Cryo-SEM), and Isotermal Titration Calorimetry (ITC). The incorporation of phosphoglycerol into the PC vesicles decreased the size and the polydispersity of the particles, due to an increase of the packing of the aliphatic chains in the layer. This phenomenon has been interpreted in terms of strong van der Waals interactions. The addition of phosphoglycerols resulted in a reduction in zeta potential (ξ) to values of -75 mV, compared to PC based-vesicles. Both systems were modified by using a high molecular weight chitosan (865 kDa) with a degree of deacetylation of 77%. Strong electrostatic interactions between the cationic polyelectrolyte and the vesicles were determined by ITC experiments. The results were reinforced by means of Z potential analysis. It has been demonstrated that a complete inverse of the vesicle surface charge is not required to perform a complete coating of the phospholipid particles. The addition of concentration of chitosan above 0,1 mg/mL induced vesicles aggregation. Aggregated vesicle-polymer structures were visualized by Cryo-SEM and measured by DLS. This behavior was more significant for the PC/DMPG-Na-/chitosan system. Vesículas a base de L-α-fosfatidilcolina (PC) e mesclas de PC/fosfogliceróis foram caracterizadas por meio de dispersão de luz dinâmica (DLS), microscopia eletrônica de varredura-criogênico (Cryo-SEM) e calorimetria de titulação isotérmica (ITC). A incorporação de fosfogliceróis na formulação de vesículas a base de PC diminuiu o tamanho e a polidispersão das partículas, devido a um maior empacotamento das cadeias alifáticas por meio de interações de van der Waals. Além disso, resultou em uma diminuição significativa da carga superficial de -75 mV comparada com o potencial Z (ξ) das vesículas a base de PC. Ambos os sistemas foram modificados usando um polieletrólito catiônico (quitosana) de um peso molecular de 865 kDa e com um grau de desacetilação de 77 %. A natureza aniônica da vesícula fosfolipídica resultou em uma interação efetiva com o polieletrólito catiônico através de forças do tipo eletrostática, que foi determinada por meio de ITC. Os resultados foram complementados por meio da determinação de potencial Z dos sistemas modificados, o qual demostrou não ser necessária uma inversão completa da carga inicial da superfície da vesícula para assegurar o recobrimento desta. A adição de concentrações de quitosana maiores a 0,1 mg/mL conduziu à agregação das vesículas, o qual foi demostrado mediante Cryo-SEM e DLS. Este efeito foi mais significativo para o sistema baseado em dimiristoil fosfoglicerol sal de sódio e quitosana, devido à forte atração eletrostática. Ministerio de Ciencia y Tecnología/[Materiales inteligentes 023930]/MICIT/Costa Rica Consejo Nacional para Investigaciones Científicas y Tecnológicas/[Materiales inteligentes 023930]/CONICIT/Costa Rica UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Química

Effective integration of molecular self-assembly and additive manufacturing would provide a technological leap in bioprinting. This article reports on a biofabrication system based on the hydrodynamically guided co-assembly of peptide amphiphiles (PAs) with naturally occurring biomolecules and proteins to generate hierarchical constructs with tuneable molecular composition and structural control. The system takes advantage of droplet-on-demand (DoD) inkjet printing to exploit interfacial fluid forces and guide molecular self-assembly into aligned or disordered nanofibers, hydrogel structures of different geometries and sizes, surface topographies and higherordered constructs bound by molecular diffusion. PAs were designed to co-assemble during printing in cell diluent conditions with a range of extracellular matrix (ECM) proteins and biomolecules including fibronectin, collagen, keratin, elastin-like proteins (ELPs) and hyaluronic acid. Using combinations of these molecules, NIH-3T3 and adipose derived stem cells were bioprinted within complex structures while exhibiting high cell viability (> 88 %). By integrating self-assembly with 3D-bioprinting, the study introduces a novel biofabrication platform capable of encapsulating and spatially distributing multiple cell types within tuneable pericellular environments. In this way, the work demonstrates the potential of the approach to generate complex bioactive scaffolds for applications such as tissue engineering, in vitro models, and drug screening.