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Natural polymers have been widely used for biomedical applications in recent decades. They offer the advantages of resembling the extracellular matrix of native tissues and retaining biochemical cues and properties necessary to enhance their biocompatibility, so they usually improve the cellular attachment and behavior and avoid immunological reactions. Moreover, they offer a rapid degradability through natural enzymatic or chemical processes. However, natural polymers present poor mechanical strength, which frequently makes the manipulation processes difficult. Recent advances in biofabrication, 3D printing, microfluidics, and cell-electrospinning allow the manufacturing of complex natural polymer matrixes with biophysical and structural properties similar to those of the extracellular matrix. In addition, these techniques offer the possibility of incorporating different cell lines into the fabrication process, a revolutionary strategy broadly explored in recent years to produce cell-laden scaffolds that can better mimic the properties of functional tissues. In this review, the use of 3D printing, microfluidics, and electrospinning approaches has been extensively investigated for the biofabrication of naturally derived polymer scaffolds with encapsulated cells intended for biomedical applications (e.g., cell therapies, bone and dental grafts, cardiovascular or musculoskeletal tissue regeneration, and wound healing).

In the present study, semi- and interpenetrated polymer network (IPN) systems based on hyaluronic acid (HA) and chitosan using ionic crosslinking of chitosan with a bioactive crosslinker, glycerylphytate (G1Phy), and UV irradiation of methacrylate were developed, characterized and evaluated as potential supports for tissue engineering. Semi- and IPN systems showed significant differences between them regarding composition, morphology, and mechanical properties after physicochemical characterization. Dual crosslinking process of IPN systems enhanced HA retention and mechanical properties, providing also flatter and denser surfaces in comparison to semi-IPN membranes. The biological performance was evaluated on primary human mesenchymal stem cells (hMSCs) and the systems revealed no cytotoxic effect. The excellent biocompatibility of the systems was demonstrated by large spreading areas of hMSCs on hydrogel membrane surfaces. Cell proliferation increased over time for all the systems, being significantly enhanced in the semi-IPN, which suggested that these polymeric membranes could be proposed as an effective promoter system of tissue repair. In this sense, the developed crosslinked biomimetic and biodegradable membranes can provide a stable and amenable environment for hMSCs support and growth with potential applications in the biomedical field.

n the present study, semi- and interpenetrated polymer network (IPN) systems based onhyaluronic acid (HA) and chitosan using ionic crosslinking of chitosan with a bioactive crosslinker,glycerylphytate (G1Phy), and UV irradiation of methacrylate were developed, characterized andevaluated as potential supports for tissue engineering. Semi- and IPN systems showed significantdifferences between them regarding composition, morphology, and mechanical properties afterphysicochemical characterization. Dual crosslinking process of IPN systems enhanced HA retentionand mechanical properties, providing also flatter and denser surfaces in comparison to semi-IPNmembranes. The biological performance was evaluated on primary human mesenchymal stemcells (hMSCs) and the systems revealed no cytotoxic effect. The excellent biocompatibility of thesystems was demonstrated by large spreading areas of hMSCs on hydrogel membrane surfaces.Cell proliferation increased over time for all the systems, being significantly enhanced in the semi-IPN,which suggested that these polymeric membranes could be proposed as an effective promoter systemof tissue repair. In this sense, the developed crosslinked biomimetic and biodegradable membranescan provide a stable and amenable environment for hMSCs support and growth with potentialapplications in the biomedical field.

Chitosan-based membranes are promising systems for guided bone regeneration. In this work, we used glycerylphytate as ionic crosslinker and osteinductor compound for the fabrication of chitosan membranes as supports for human mesenchymal stem cells. Three different glycerylphytate-crosslinked membranes were developed by changing the crosslinker concentration, from 2.5–10 wt-%, respect to chitosan. Physico-chemical characterization in terms of composition, morphology, and thermal behavior was further analyzed. Swelling degree, crosslinking density, and crosslinker release showed a glycerylphytate content-dependent behavior. Glycerylphytate suggested to improve osteointegration ability of chitosan surfaces by the formation of apatite-like aggregates after incubation in body simulated fluid. Stem cells cultured on the membranes increased their viability over time, and the incorporation of glycerylphytate improved osteogenic and osteoinductivity potential of chitosan by increasing calcium deposition and alkaline phosphatase (ALP) activity on cultured stem cells. These results demonstrated a potential application of glycerylphytate-crosslinked chitosan systems for promising bone tissue regeneration.

El campo de la impresión y la bioimpresión 3D ha alcanzado un gran desarrollo en los últimos años. La llegada de estas técnicas de biofabricación a la ingeniería tisular han supuesto una revolución debido a las estructuras biomiméticas tan complejas que permiten sintetizar. El uso del quitosano como componente de tintas basadas en polímeros naturales es muy atractivo debido a las propiedades beneficiosas que presenta (alta biocompatibilidad, biodegradabilidad, bajo coste). Sin embargo, su aplicación se ve limitada por su baja solubilidad en condiciones fisiológicas y sus pobres propiedades mecánicas. En este artículo, revisamos el estado del arte relacionado con las estrategias actuales de impresión 3D que hacen uso de tintas y biotintas basadas en quitosano para el desarrollo de soportes biomiméticos. También analizamos las estrategias de entrecruzamiento que se aplican actualmente para mejorar su printabilidad, resaltando además los derivados de quitosano disponibles que permiten encapsular células para bioimpresión 3D, incluyendo además nuestra contribución al campo. Prevemos que el uso de quitosano en la impresión 3D aumentará significativamente en los próximos años gracias a los esfuerzos que se están desarrollando en términos de mecanismos de gelificación y derivados de quitosano que permiten la encapsulación celular., El campo de la impresión y la bioimpresión 3D ha alcanzado un gran desarrollo en los últimos años. La llegada de estas técnicas de biofabricación a la ingeniería tisular han supuesto una revolución debido a las estructuras biomiméticas tan complejas que permiten sintetizar. El uso del quitosano como componente de tintas basadas en polímeros naturales es muy atractivo debido a las propiedades beneficiosas que presenta (alta biocompatibilidad, biodegradabilidad, bajo coste). Sin embargo, su aplicación se ve limitada por su baja solubilidad en condiciones fisiológicas y sus pobres propiedades mecánicas. En este artículo, revisamos el estado del arte relacionado con las estrategias actuales de impresión 3D que hacen uso de tintas y biotintas basadas en quitosano para el desarrollo de soportes biomiméticos. También analizamos las estrategias de entrecruzamiento que se aplican actualmente para mejorar su printabilidad, resaltando además los derivados de quitosano disponibles que permiten encapsular células para bioimpresión 3D, incluyendo además nuestra contribución al campo. Prevemos que el uso de quitosano en la impresión 3D aumentará significativamente en los próximos años gracias a los esfuerzos que se están desarrollando en términos de mecanismos de gelificación y derivados de quitosano que permiten la encapsulación celular.

Phytic acid (PA) is a natural-occurring antioxidant, which plays an important role in many biological processes. PA is recognized as a potent inhibitor of lipid peroxidation because of its high affinity to multivalent cations, and it can play a role in osteogenic processes. However, its powerful chelating capacity is controversial because it can lead to a severe reduction of mineral availability in the organism. For this reason, compounds with beneficial biological properties of PA, but a modular ion binding capacity, are of high interest. In this work, we report the synthesis and physicochemical characterization of two hydroxylic derivatives of PA, named glycerylphytates (GPhy), through a condensation reaction of PA with glycerol (G). Both derivatives present antioxidant properties, measured by ferrozine/FeCl method and chelating activity with calcium ions depending on the content of glyceryl groups incorporated. Besides, the hydroxylic modification not only modulates the ion binding affinity of derivatives but also improves their cytocompatibility in human bone marrow mesenchymal cells (MSCs). Furthermore, GPhy derivatives display osteogenic properties, confirmed by COL1A and ALPL expression depending on composition. These positive features convert GPhy compounds into potent alternatives for those skeletal diseases treatments where PA is tentatively applied.

This chapter summarizes the properties and most representative applications of pH-responsive polymers in the biomedical field. The most common methodologies to synthesize pH-responsive polymers such as emulsion polymerization, group transfer polymerization, atom transfer radical polymerization and reversible addition-fragmentation chain transfer polymerization are described. This chapter also discusses the most important applications of pH-responsive polymers in drug and gene delivery and the use of these systems as biosensors, taking into account the chemical and physical properties of these smart polymer systems.

Premio Congreso SIBB 2018, El campo de la impresión y la bioimpresión 3D ha alcanzado un gran desarrollo en los últimos años. La llegada de estas técnicas de biofabricación a la ingeniería tisular han supuesto una revolución debido a las estructuras biomiméticas tan complejas que permiten sintetizar. El uso del quitosano como componente de tintas basadas en polímeros naturales es muy atractivo debido a las propiedades beneficiosas que presenta (alta biocompatibilidad, biodegradabilidad, bajo coste). Sin embargo, su aplicación se ve limitada por su baja solubilidad en condiciones fisiológicas y sus pobres propiedades mecánicas. En este artículo, revisamos el estado del arte relacionado con las estrategias actuales de impresión 3D que hacen uso de tintas y biotintas basadas en quitosano para el desarrollo de soportes biomiméticos. También analizamos las estrategias de entrecruzamiento que se aplican actualmente para mejorar su printabilidad, resaltando además los derivados de quitosano disponibles que permiten encapsular células para bioimpresión 3D, incluyendo además nuestra contribución al campo. Prevemos que el uso de quitosano en la impresión 3D aumentará significativamente en los próximos años gracias a los esfuerzos que se están desarrollando en términos de mecanismos de gelificación y derivados de quitosano que permiten la encapsulación celular., Premio Congreso SIBB 2018, Award-winning, Peer Reviewed

Novedosos agentes reticulantes de ácido fítico. La presente invención describe membranas novedosas, estables y biodegradables de proteínas y/o polisacáridos, particularmente de quitosano y quitosano/ácido hialurónico, útiles como armazones para la ingeniería de tejido óseo. Estas membranas fueron fabricadas por mezclas de polisacáridos y proteínas de interés y novedosos agentes de reticulación que consisten en derivados de ácido fítico (PA) obtenidos por una reacción de condensación entre ácido fítico (PA) con un compuesto hidroxílico.

An overview of the most relevant crosslinking processes and agents that are being developed for regenerative medicine, including different hydrogel modifications as well as several interesting and advanced applications. The functionality and reactivity of polysaccharides and in particular hyaluronic acid in combination with proteins like gelatin, collagen and many others offer very interesting opportunities for the new trends in regenerative medicine. The biomimetic approaches for the application in regenerative processes and tissue engineering have enormous possibilities because of the excellent response of these biomimetic materials and their bioactive and biodegradable character in the human body. These characteristics together with the possibility of application by minimally invasive surgery offer very interesting applications in regeneration of tissues and organs, as well as in targeting and releasing of bioactive compounds applications as drug delivery systems. In addition, the growing of clinical applications of these macromolecular components as assemblies opens new and advanced opportunities in regenerative medicine and drug delivery fields.

This study shows the fabrication by a dry approach at mild temperature (<150 °C) of a photoluminescence white light emitting hybrid layer. The white light emitter is obtained by evaporation of two photoluminescent small molecules, a blue (1,3,5-triphenyl-2-pyrazoline (TPP)) and an orange (Rubrene) dye within the porous of an SiO host film fabricated by glancing angle deposition. Fluorescence (Föster) resonant energy transfer between the two organic dyes allows the emission of the combined system upon excitation of the TPP molecule at wavelength of 365 nm. The distribution of the organic molecule within the host layer is analyzed as a function of the substrate temperature and vacuum conditions and the required conditions for the white emission determined by finely controlling the TPP:Rubrene ratio. The full vacuum processing of the hybrid layers provides a straightforward route for the incorporation of the white light emitters as optical defect within 1D Bragg microcavities. As a consequence, directional emission of the system is achieved which allows the development of wide-range in situ tunable photoluminescent devices.