Nanostructured 3D Constructs Based on Chitosan and Chondroitin Sulphate Multilayers for Cartilage Tissue Engineering

Nanostructured three-dimensional constructs combining layer-by-layer technology (LbL) and template leaching were processed and evaluated as possible support structures for cartilage tissue engineering. Multilayered constructs were formed by depositing the polyelectrolytes chitosan (CHT) and chondroitin sulphate (CS) on either bidimensional glass surfaces or 3D packet of paraffin spheres. 2D CHT/CS multi-layered constructs proved to support the attachment and proliferation of bovine chondrocytes (BCH). The technology was transposed to 3D level and CHT/CS multi-layered hierarchical scaffolds were retrieved after paraffin leaching. The obtained nanostructured 3D constructs had a high porosity and water uptake capacity of about 300%. Dynamical mechanical analysis (DMA) showed the viscoelastic nature of the scaffolds. Cellular tests were performed with the culture of BCH and multipotent bone marrow derived stromal cells (hMSCs) up to 21 days in chondrogenic differentiation media. Together with scanning electronic microscopy analysis, viability tests and DNA quantification, our results clearly showed that cells attached, proliferated and were metabolically active over the entire scaffold. Cartilaginous extracellular matrix (ECM) formation was further assessed and results showed that GAG secretion occurred indicating the maintenance of the chondrogenic phenotype and the chondrogenic differentiation of hMSCs

Highly porous scaffolds of PEDOT:PSS for bone tissue engineering.

UNLABELLED: Conjugated polymers have been increasingly considered for the design of conductive materials in the field of regenerative medicine. However, optimal scaffold properties addressing the complexity of the desired tissue still need to be developed. The focus of this study lies in the development and evaluation of a conductive scaffold for bone tissue engineering. In this study PEDOT:PSS scaffolds were designed and evaluated in vitro using MC3T3-E1 osteogenic precursor cells, and the cells were assessed for distinct differentiation stages and the expression of an osteogenic phenotype. Ice-templated PEDOT:PSS scaffolds presented high pore interconnectivity with a median pore diameter of 53.6±5.9µm and a total pore surface area of 7.72±1.7m2·g-1. The electrical conductivity, based on I-V curves, was measured to be 140µS·cm-1 with a reduced, but stable conductivity of 6.1µS·cm-1 after 28days in cell culture media. MC3T3-E1 gene expression levels of ALPL, COL1A1 and RUNX2 were significantly enhanced after 4weeks, in line with increased extracellular matrix mineralisation, and osteocalcin deposition. These results demonstrate that a porous material, based purely on PEDOT:PSS, is suitable as a scaffold for bone tissue engineering and thus represents a promising candidate for regenerative medicine. STATEMENT OF SIGNIFICANCE: Tissue engineering approaches have been increasingly considered for the repair of non-union fractions, craniofacial reconstruction or large bone defect replacements. The design of complex biomaterials and successful engineering of 3-dimensional tissue constructs is of paramount importance to meet this clinical need. Conductive scaffolds, based on conjugated polymers, present interesting candidates to address the piezoelectric properties of bone tissue and to induce enhanced osteogenesis upon implantation. However, conductive scaffolds have not been investigated in vitro in great measure. To this end, we have developed a highly porous, electrically conductive scaffold based on PEDOT:PSS, and provide evidence that this purely synthetic material is a promising candidate for bone tissue engineering

Chitosan nanocomposites based on distinct inorganic fillers for biomedical applications

AbstractChitosan (CHI), a biocompatible and biodegradable polysaccharide with the ability to provide a non-protein matrix for tissue growth, is considered to be an ideal material in the biomedical field. However, the lack of good mechanical properties limits its applications. In order to overcome this drawback, CHI has been combined with different polymers and fillers, leading to a variety of chitosan-based nanocomposites. The extensive research on CHI nanocomposites as well as their main biomedical applications are reviewed in this paper. An overview of the different fillers and assembly techniques available to produce CHI nanocomposites is presented. Finally, the properties of such nanocomposites are discussed with particular focus on bone regeneration, drug delivery, wound healing and biosensing applications

Additive Manufacturing of Conducting Polymers: Recent Advances, Challenges and Opportunities

Unformatted postprintConducting polymers (CPs) have been attracting great attention in the development of (bio)electronic devices. Most of current devices are rigid 2D systems and possess uncontrollable geometries and architectures that lead to poor mechanical properties presenting ion/electronic diffusion limitations. The goal of the article is to provide an overview about the additive manufacturing (AM) of conducting polymers, which is of paramount importance for the design of future wearable 3D (bio)electronic devices. Among different 3D printing AM techniques, inkjet, extrusion, electrohydrodynamic and light-based printing have been mainly used. This review article collects examples of 3D printing of conducting polymers such as poly(3,4-ethylene-dioxythiophene) (PEDOT), polypyrrole (PPy) and polyaniline (PANi). It also shows examples of AM of these polymers combined with other polymers and/or conducting fillers such as carbon nanotubes, graphene and silver nanowires. Afterwards, the foremost application of CPs processed by 3D printing techniques in the biomedical and energy fields, i.e., wearable electronics, sensors, soft robotics for human motion, or health monitoring devices, among others, will be discussed.This work was supported by Marie Sklodowska-Curie Research and Innovation Staff Exchanges (RISE) under the grant agreement No 823989 “IONBIKE”. N.A. has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 753293, acronym NanoBEAT

Estruturas tridimensionais eletro-estimuláveis à base de nanoestruturas de carbono/hidrogel para engenharia de tecido neuronal

The main objective of the present work consists of the optimization of the production of three-dimensional electro-responsive carbon-reinforced hydrogels, to study their cytocompatibility with neural stem cells (NSCs) for neural tissue engineering. For that matter, initially vertically aligned carbon nanotubes (VA-CNTs) with two different patterns were prepared by thermal chemical vapor deposition (T-CVD): (1) VA-CNTs dense forest and (1) VA-CNTs micropillars. Furthermore, the substrates previously described were studied after acetone vapor treatment, resulting in a cellular and “flower-like” pattern morphology, respectively. Structural characterization of the respective samples was made using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and the measurement of the water contact angle (WCA). The integration with gelatinmethacryloyl (GelMA) -based hydrogels were explored in the different studied samples. The influence of the different VA-CNTs prepared patterns was studied by the evaluation of the cell behavior with resort to NSCs. By immunocytochemical staining, cell viability assays and SEM, it was observed the cells affinity for the diverse carbon structures, in comparison to the silicon (Si) substrate. Besides, it was also verified the suitability of the VA-CNTs platforms for cell viability and proliferation. The collapsed VA-CNTs substrate made evident the tendency for cell differentiation into neurons, possibly due to their superficial roughness at the nanoscale, which favors this biological mechanism. The results obtained demonstrated that VA-CNTs based structures favors the proliferation and differentiation of NSCs, making them promising as future threedimensional electroresponsive structures with excellent performances for neural tissue engineering.O principal objetivo do presente trabalho constituiu na otimização da produção de estruturas tridimensionais eletro-estimuláveis à base de nanoestruturas de carbono/hidrogel, estudando a sua citocompatibilidade com células estaminais para engenharia de tecido neuronal. Nesse sentido foram primeiramente preparados dois padrões de nanotubos de carbono verticalmente alinhados (VA-CNTs) por deposição química em fase vapor (T-CVD): (1) floresta densa de VA-CNTs e (2) micropilares de VA-CNTs. Além disso, foram também estudados os substratos anteriormente descritos após tratamento por vapor de acetona, resultando na formação de VA-CNTs e micropadrões colapsados, apresentando uma morfologia com um padrão celular e uma semelhante a uma "flor", respetivamente. As respetivas amostras foram caracterizadas por microscopia eletrónica de varrimento (SEM), de transmissão (TEM) e foi medido o ângulo de contacto com a água (WCA). As diferentes amostras estudadas foram exploradas na integração com hidrogéis à base de gelatina metacrilada (GelMA). A influência dos diferentes padrões de VA-CNTs preparados foi estudada através da avaliação do comportamento celular com o recurso a células estaminais neurais (NSCs). Por ensaios de imunocitoquímica, viabilidade celular e SEM, foi observada a afinidade das células para com as diversas estruturas de carbono, em comparação com o substrato de silício (Si). Para além disso foi também verificada a aptidão das diversas estruturas baseadas em VA-CNTs como plataformas para proliferação e diferenciação de NSCs. Os substratos de VA-CNTs colapsados evidenciaram uma propensão para induzir a diferenciação celular em neurónios, possivelmente devido à sua rugosidade superficial à nanoescala favorecer este mecanismo biológico. Os resultados obtidos demonstraram que as estruturas baseadas em VA-CNTs favorecem a proliferação e diferenciação das células estaminais neurais, podendo futuramente ser aplicados como estruturas tridimensionais eletroestimuláveis com elevado desempenho para engenharia de tecido neural.Mestrado em Materiais e Dispositivos Biomédico

Functional applications of electrospun nanofibers

With the rapid development of nanoscience and nanotechnology over the last two decades, great progress has been made not only in preparation and characterization of nanomaterials, but also in their functional applications. As an important one-dimensional nanomaterial, nanofibers have extremely high specific surface area because of their small diameters, and nanofiber membranes are highly porous with excellent pore interconnectivity. These unique characteristics plus the functionalities from the polymers themselves impart nanofibers with many desirable properties for advanced applications

Structural Design, Fabrication and Evaluation of Resorbable Fiber-Based Tissue Engineering Scaffolds

The use of tissue engineering to regenerate viable tissue relies on selecting the appropriate cell line, developing a resorbable scaffold and optimizing the culture conditions including the use of biomolecular cues and sometimes mechanical stimulation. This review of the literature focuses on the required scaffold properties, including the polymer material, the structural design, the total porosity, pore size distribution, mechanical performance, physical integrity in multiphase structures as well as surface morphology, rate of resorption and biocompatibility. The chapter will explain the unique advantages of using textile technologies for tissue engineering scaffold fabrication, and will delineate the differences in design, fabrication and performance of woven, warp and weft knitted, braided, nonwoven and electrospun scaffolds. In addition, it will explain how different types of tissues can be regenerated by each textile technology for a particular clinical application. The use of different synthetic and natural resorbable polymer fibers will be discussed, as well as the need for specialized finishing techniques such as heat setting, cross linking, coating and impregnation, depending on the tissue engineering application