Functionally Graded Biomaterials for Use as Model Systems and Replacement Tissues

Abstract

The heterogeneity of native tissues requires complex materials to provide suitable substitutes for model systems and replacement tissues. Functionally graded materials have the potential to address this challenge by mimicking the gradients in heterogeneous tissues such as porosity, mineralization, and fiber alignment to influence strength, ductility, and cell signaling. Advancements in microfluidics, electrospinning, and 3D printing enable the creation of increasingly complex gradient materials that further the understanding of physiological gradients. The combination of these methods enables rapid prototyping of constructs with high spatial resolution. However, successful translation of these gradients requires both spatial and temporal presentation of cues to model the complexity of native tissues that few materials have demonstrated. This Review highlights recent strategies to engineer functionally graded materials for the modeling and repair of heterogeneous tissues, together with a description of how cells interact with various gradients.

3D Printing of Strong and Tough Double Network Granular Hydrogels

“…Hydrogels are often used for moisturizing purposes, for example in wound healing, [1] drug delivery, [2] or food [3] owing to their ability to retain large amounts of water, intrinsic biocompatibility, and the possibility to be functionalized with various moieties. In addition, hydrogels possess the ability to retain a 3D structure and to support cell growth rendering them well-suited replacements for soft biological tissues, [4][5][6] and for soft robotics. [7][8][9] Most hydrogels that must retain their 3D structure and bear some load are covalently cross-linked and hence, if swollen, they are inherently brittle.…”

Morphology, Thermal and Mechanical Properties of Co-Continuous Porous Structure of PLA/PVA Blends by Phase Separation

“…Poly(lactic acid) (PLA) has attracted considerable attention as an alternative material for biomedical applications (e.g., surgical sutures, artificial skin, drug delivery materials, scaffolds, packaging, and tissue engineering) because PLA is renewable, processable, energy-saving, biodegradable, and biocompatible [ 1 , 2 , 3 , 4 , 5 , 6 ]. Tissue engineering relies on material properties and cell transportation to repair and regenerate bond defects [ 7 , 8 ].…”

Articular cartilage and osteochondral tissue engineering techniques: Recent advances and challenges

“…To imitate this natural paradigm and translate such design motif into bioinspired applications in osteochondral tissue engineering, multiphasic discrete gradient (more than three layers in this section) and continuous gradient scaffolds in a stepwise mode and a gradual manner respectively have been exploited to achieve gradients in a broad scale throughout the entire construct or within a limited interface region. Gradient scaffolds consistently perform superior to monophasic and biphasic ones in regenerating osteochondral defects [ 256 , 257 ]. The gradients can be described in terms of the variations of the basic units in chemical compositions and structural characteristics which further include several basic forms in arrangement, distribution, dimension and orientation [ 258 ].…”

“…( Fig. 8 C) Gradients created by photolithography can be realized through the manipulation of cross-linker concentration, applied wavelength and duration of irradiation [ 256 ]. By moving the opaque sliding mask below the UV light across the exposed hydrogel at a constant rate, continuous peptide gradients were achieved through the thiol-norbornene chemistry in the photocrosslinked HA-based hydrogel.…”

“…The importance of the interface has been taken into account in the triphasic scaffold that can better resembling the osteochondral stratification [ 112 , 251 ]. More recently, efforts have been paid to construct gradient scaffolds with gradient chemical compositions and structural characteristics, whether in multiphasic or continuous mode, which showed promising to imitate the native osteochondral tissues in a more superior way [ 256 , 280 ]. But the research concerning the development of gradient tissue engineering scaffolds is still in its early stage.…”