The search for materials with improved mechanical and biological properties is a major challenge in tissue engineering. This paper investigates, for the first time, the use of Polyethylene Terephthalate Glycol (PETG), a glycol-modified class of Polyethylene Terephthalate (PET), as a potential material for the fabrication of bone scaffolds. PETG scaffolds with a 0/90 lay-dawn pattern and different pore sizes (300, 350 and 450 µm) were produced using a filament-based extrusion additive manufacturing system and mechanically and biologically characterized. The performance of PETG scaffolds with 300 µm of pore size was compared with polycaprolactone (PCL). Results show that PETG scaffolds present significantly higher mechanical properties than PCL scaffolds, providing a biomechanical environment that promotes high cell attachment and proliferation.
The use of electrically conductive materials to impart electrical properties to substrates for cell attachment proliferation and differentiation represents an important strategy in the field of tissue engineering. This paper discusses the concept of electro-active structures and their roles in tissue engineering, accelerating cell proliferation and differentiation, consequently leading to tissue regeneration. The most relevant carbon-based materials used to produce electro-active structures are presented, and their main advantages and limitations are discussed in detail. Particular emphasis is put on the electrically conductive property, material synthesis and their applications on tissue engineering. Different technologies, allowing the fabrication of two-dimensional and three-dimensional structures in a controlled way, are also presented. Finally, challenges for future research are highlighted. This review shows that electrical stimulation plays an important role in modulating the growth of different types of cells. As highlighted, carbon nanomaterials, especially graphene and carbon nanotubes, have great potential for fabricating electro-active structures due to their exceptional electrical and surface properties, opening new routes for more efficient tissue engineering approaches.
Scaffolds play a key role in tissue engineering applications. In the case of bone tissue engineering, scaffolds are expected to provide both sufficient mechanical properties to withstand the physiological loads, and appropriate bioactivity to stimulate cell growth. In order to further enhance cell–cell signaling and cell–material interaction, electro-active scaffolds have been developed based on the use of electrically conductive biomaterials or blending electrically conductive fillers to non-conductive biomaterials. Graphene has been widely used as functioning filler for the fabrication of electro-active bone tissue engineering scaffolds, due to its high electrical conductivity and potential to enhance both mechanical and biological properties. Nitrogen-doped graphene, a unique form of graphene-derived nanomaterials, presents significantly higher electrical conductivity than pristine graphene, and better surface hydrophilicity while maintaining a similar mechanical property. This paper investigates the synthesis and use of high-performance nitrogen-doped graphene as a functional filler of poly(ɛ-caprolactone) (PCL) scaffolds enabling to develop the next generation of electro-active scaffolds. Compared to PCL scaffolds and PCL/graphene scaffolds, these novel scaffolds present improved in vitro biological performance.
Topology optimization (TO) of microstructures plays a critical role in optimizing functional performance across diverse engineering applications. While metamaterials with enhanced mechanical properties—such as hyperelasticity, energy absorption, and thermal efficiency—are commonly designed using complex microstructural geometries and multi‐physics simulations, achieving the simultaneous optimization of mechanical performance and non‐differentiable objectives remains a significant challenge. In this work, a novel framework is proposed for simultaneous TO of differentiable and non‐differentiable objectives via a data‐driven morphology learning approach. The framework extracts shape patterns from a curated dataset of microstructures recognized for their superior performance in specific functional applications. To showcase the versatility of the approach, it is applied to the optimization of scaffolds for bone tissue engineering, with cell growth as a representative functional objective. By integrating learned morphology patterns into a TO process, the method generates microstructures that effectively balance mechanical stiffness and biological performance, such as enhanced cell proliferation. As a case study, a scaffold design that improves mechanical stiffness by 29.69% and cell growth by 37.05% on day 7 and 33.30% on day 14 is demonstrated. This approach highlights the general applicability of the proposed framework for optimizing a broad range of engineering challenges, beyond the specific case of cell growth.
19 October 2023 in Macromolecular Materials and Engineering
Electrospinning has emerged as one of the major technologies for designing and fabricating tissue engineering membranes. The resemblance of the electrospun fiber structure to blood capillaries endowed them with unique capabilities to mimic the native tissue biological characteristics, while the high surface‐to‐volume ratio enables them to exert a controlled release of drug directly to the exposed interstitial tissue. This research attempts to compare the characteristics of different electrospun polyvinyl alcohol/hyaluronic acid (PVA/HA) composite material nanofibrous membranes in order to identify the optimal material‐fabrication combination for wound dressing and skin tissue engineering applications. Far‐field electrospinning equipped with both rotatory and wire collectors is considered for membrane fabrication. PVA with different concentrations and molecular weights of HA are electrospun as nanofibrous membranes considering a voltage of 30 kV on both types of collectors. Comprehensive characterization is conducted including morphological, chemical, thermal, mechanical, and in vitro mucoadhesion analysis. In vitro cell viability/proliferation studies are also carried out and pointed out that the designed membranes are cytocompatible, and able to support keratinocytes proliferation. All these results proved that the fabricated PVA/HA nanofibrous membranes are suitable for wound dressing and skin tissue engineering applications, the optimal material‐fabrication combination is also determined.