Biofabrication using well-matched cell/materials systems provides unprecedented opportunities for dealing with human health issues where disease or injury overtake the body’s native regenerative abilities. Such opportunities can be enhanced through the development of biomaterials with cues that appropriately influence embedded cells into forming functional tissues and organs. In this context, biomaterials’ reliance on rigid biofabrication techniques needs to support the incorporation of a hierarchical mimicry of local and bulk biological cues that mimic the key functional components of native extracellular matrix. Advances in synthetic self-assembling peptide biomaterials promise to produce reproducible mimics of tissue-specific structures and may go some way in overcoming batch inconsistency issues of naturally sourced materials. Recent work in this area has demonstrated biofabrication with self-assembling peptide biomaterials with unique biofabrication technologies to support structural fidelity upon 3D patterning. The use of synthetic self-assembling peptide biomaterials is a growing field that has demonstrated applicability in dermal, intestinal, muscle, cancer and stem cell tissue engineering.

A significant challenge to current cancer drug treatment is mode of delivery, both in terms of efficacy and off-target toxicity to healthy tissues. To overcome this, drug localisation using a range of biocompatible carriers is currently in use or under investigation. One class of these biomaterial carriers that offers a unique prospect for use as drug delivery vectors to tumour sites is hydrogels formed by small molecules. In particular, tissue mimetic self-assembling molecular hydrogels can function either as injectable precursors that gelate in response to tumour-specific markers, or as implants in conjunction with surgical resection or tumour debulking. Their inherent biocompatibility, tuneable properties, and capacity to flow and gelate in situ allow them to effectively transport, hold and release therapeutic molecules in a spatially and temporally controlled manner. This has been shown in a number of in vitro and in vivo studies, where they improve anti-cancer efficacy while reducing non-specific toxicity. However, further investigation is required to optimise these systems toward both the drug and the target tissue, to provide sophisticated temporal control over the drug presentation, and to determine the most effective drug–material combinations for specific cancer types and locations.

The debilitating effects of muscle damage, either through ischemic injury or volumetric muscle loss (VML), can have significant impacts on patients, and yet there are few effective treatments. This challenge arises when function is degraded due to significant amounts of skeletal muscle loss, beyond the regenerative ability of endogenous repair mechanisms. Currently available surgical interventions for VML are quite invasive and cannot typically restore function adequately. In response to this, many new bioengineering studies implicate 3D bioprinting as a viable option. Bioprinting for VML repair includes three distinct phases: printing and seeding, growth and maturation, and implantation and application. Although this 3D bioprinting technology has existed for several decades, the advent of more advanced and novel printing techniques has brought us closer to clinical applications. Recent studies have overcome previous limitations in diffusion distance with novel microchannel construct architectures and improved myotubule alignment with highly biomimetic nanostructures. These structures may also enhance angiogenic and nervous ingrowth post-implantation, though further research to improve these parameters has been limited. Inclusion of neural cells has also shown to improve myoblast maturation and development of neuromuscular junctions, bringing us one step closer to functional, implantable skeletal muscle constructs. Given the current state of skeletal muscle 3D bioprinting, the most pressing future avenues of research include furthering our understanding of the physical and biochemical mechanisms of myotube development and expanding our control over macroscopic and microscopic construct structures. Further to this, current investigation needs to be expanded from immunocompromised rodent and murine myoblast models to more clinically applicable human cell lines as we move closer to viable therapeutic implementation.

Small-angle X-ray scattering is used to unpack the hidden structure of a gelatin methacryloyl (GelMA) biogel. We present insights regarding how the degree of functionalisation, crosslinked polymer conformation, nanoscale mesh size and macroscale mechanical properties are interlinked.