Self-assembled peptide habitats to model tumor metastasis

Metastatic tumours are complex ecosystems; a community of multiple cell types, including cancerous cells, fibroblasts, and immune cells that exist within a supportive and specific microenvironment. The interplay of these cells, together with tissue specific chemical, structural and temporal signals within a three-dimensional (3D) habitat, direct tumour cell behavior, a subtlety that can be easily lost in 2D tissue culture. Here, we investigate a significantly improved tool, consisting of a novel matrix of functionally programmed peptide sequences, self-assembled into a scaffold to enable the growth and the migration of multicellular lung tumour spheroids, as proof-of-concept. This 3D functional model aims to mimic the biological, chemical, and contextual cues of an in vivo tumor more closely than a typically used, unstructured hydrogel, allowing spatial and temporal activity modelling. This approach shows promise as a cancer model, enhancing current understandings of how tumours progress and spread over time within their microenvironment. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Hybrid self‐assembling peptide/gelatin methacrylate (gelma) bioink blend for improved bioprintability and primary myoblast response

Organ fabrication as the solution to renewable donor demands requires the ability to spatially deposit viable cells into biologically relevant constructs necessitating reliable and effective cell deposition through bioprinting and the subsequent ability to mature. However, effective bioink development demands advances in both printability and control of cellular response. Effective bioinks are designed to retain shape fidelity, influence cellular behavior, having bioactive morphologies stiffness and highly hydrated environment. Hybrid hydrogels are promising candidates as they reduce the need to re‐engineer materials for tissue‐specific properties, with each component offering beneficial properties. Herein, a multicomponent bioink is developed whereby gelatin methacrylate (GelMA) and fluorenylmethoxycarbonyprotected self‐assembling peptides (Fmoc‐SAPs) undergo coassembly to yield a tuneable bioink. This study shows that the reported fibronectin‐inspired fmoc‐SAPs present cell attachment epitopes RGD and PHSRN in the form of bioactive nanofibers and that the GelMA enables superior printability, stability in media, and controlled mechanical properties. Importantly, when in the hybrid format, no disruption to either the methacrylate crosslinking of GelMA, or self‐assembled peptide fibril formation is observed. Finally, studies with primary myoblasts show over 98% viability at 72 h and differentiation into fused myotubes at one and two weeks demonstrate the utility of the material as a functional bioink for muscle engineering. In this work, muscle tissue is 3D‐bioprinted with a novel bioink formulation. The bioink presents fibrous bioactive properties of the body's native scaffold, while also improving biofabrication outcomes. Self‐assembling peptides are combined with GelMA creating a hybrid bioink. This work sets the stage for future hybrid bioinks for muscle biofabrication

Shining a light on the hidden structure of gelatin methacryloyl bioinks using small-angle x-ray scattering (SAXS)

The challenge with engineering soft materials is to find a chemically functionalized material that can be easily fabricated into complex structures while providing a supportive cellular milieu. The current gold standard is gelatin methacryloyl (GelMA), a semi-synthetic collagen-derived biomaterial that has found widespread utility as a bioink for 3D bioprinting. Although a fundamental understanding of controlling the mechanical properties of GelMA exists, the nano- and cell-scale network topology needs to be investigated to produce controlled structures. Here, for the first time, small-angle X-ray scattering (SAXS) is used to elucidate how structural changes on the network level dictate the final properties within a GelMA hydrogel. Scaffold nanostructure was observed pre- and post-crosslinking, with emphasis on assessing structural changes in response to changes in Degree of Functionalization (DoF) and polymer concentration. Samples were modelled regarding local-polymer conformation (mass fractal dimension), distance between entanglements (correlation length), and mesh size. Importantly, DoF is observed to alter crosslinked polymer conformation and nanoscale mesh size. These results inform future design of GelMA-based bioinks, allowing researchers to further leverage the young and evolving bioprinting technology for broad-spectrum applications such as cell/stem cell printing, organoid-based tissue structure, building cell/organ-on-a-chip, through to the hierarchical engineering of multicellular living systems. © 2021 the Partner Organisations. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliate “Benjamin Long" is provided in this record*

Rational design of additively manufactured Ti6Al4V implants to control Staphylococcus aureus biofilm formation

Bacterial attachment and subsequent biofilm formation on medical implants presents a serious infection risk. The precision, personalisation and superior functionality of additive manufacturing techniques, such as selective laser melting (SLM), enables the fabrication of metallic implants with patient specific customisation. An unexpected outcome of this process, however, is a hitherto unachievable fine control over the bio-interface in a single manufacturing step. Here, for the first time, we report on how the SLM build inclination angle can be utilised to modify the surface topography of metallic implants for directed Staphylococcus aureus biofilm restriction. From an initial build inclination angle of 90°, lowering the angle gave metallic surfaces with lower roughness, lower hydrophobicity, higher surface energy, and fewer partially melted metal particles without altering the bulk surface chemistry. This directly correlated with significantly lower biofilm coverage and an associated reduction in biomass without compromising mammalian cell viability and attachment. This work provides facile single step method at the manufacturing stage for the development of additively manufactured metallic implants with superior, inherent protection against implant associated infection.</p

Multifunctional Sutures with Temperature Sensing and Infection Control

The next-generation sutures should provide in situ monitoring of wound condition such as temperature while reducing surgical site infection during wound closure. In this study, functionalized nanodiamond (FND) and reduced graphene oxide (rGO) into biodegradable polycaprolactone (PCL) are incorporated to develop a new multifunctional suture with such capabilities. Incorporation of FND and rGO into PCL enhances its tensile strength by about 43% and toughness by 35%. The sutures show temperature sensing capability in the range of 25–40 °C based on the shift in zero-splitting frequency of the nitrogen-vacancy (NV–) centers in FND via optically detected magnetic resonance, paving the way for potential detection of infection or excessive inflammation in healing wounds. The suture surface readily coats with antibiotics to reduce bacterial infection risk to the wounds. The new suture thus is promising in monitoring and supporting wound closure.</p

Shining a light on the hidden structure of gelatin methacryloyl bioinks using small-angle X-ray scattering (SAXS)

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.</jats:p

3D-printed diamond-titanium composite: A hybrid material for implant engineering

Diamond-based implant materials make up an emerging research area where the materials could be prepared to promote cellular functions, decrease bacteria attachment, and be suitable for potential in situ imaging. Up until now, diamond implants have been fabricated using coating technologies or embedding diamond nanoparticles in polymer matrices. Here we demonstrated a method of manufacturing diamond implants using laser cladding technology to 3D print a composite of diamond and fused titanium material. Using this method, we could prepare composite scaffolds of up to 50% diamond, which has never been achieved before. We next investigated the interfacial properties of these scaffolds for potential applications in implants. The addition of diamond to the biomaterial results in a 30% decrease in the water contact angle, making the scaffolds more hydrophilic and improving cellular adhesion and proliferation.</p

Hybrid Self-Assembling Peptide/Gelatin Methacrylate (GelMA) Bioink Blend for Improved BioPrintability and Primary Myoblast Response

Organ fabrication as the solution to renewable donor demands requires the ability to spatially deposit viable cells into biologically relevant constructs necessitating reliable and effective cell deposition through bioprinting and the subsequent ability to mature. However, effective bioink development demands advances in both printability and control of cellular response. Effective bioinks are designed to retain shape fidelity, influence cellular behavior, having bioactive morphologies stiffness and highly hydrated environment. Hybrid hydrogels are promising candidates as they reduce the need to re‐engineer materials for tissue‐specific properties, with each component offering beneficial properties. Herein, a multicomponent bioink is developed whereby gelatin methacrylate (GelMA) and fluorenylmethoxycarbonyprotected self‐assembling peptides (Fmoc‐SAPs) undergo coassembly to yield a tuneable bioink. This study shows that the reported fibronectin‐inspired fmoc‐SAPs present cell attachment epitopes RGD and PHSRN in the form of bioactive nanofibers and that the GelMA enables superior printability, stability in media, and controlled mechanical properties. Importantly, when in the hybrid format, no disruption to either the methacrylate crosslinking of GelMA, or self‐assembled peptide fibril formation is observed. Finally, studies with primary myoblasts show over 98% viability at 72 h and differentiation into fused myotubes at one and two weeks demonstrate the utility of the material as a functional bioink for muscle engineering. In this work, muscle tissue is 3D‐bioprinted with a novel bioink formulation. The bioink presents fibrous bioactive properties of the body's native scaffold, while also improving biofabrication outcomes. Self‐assembling peptides are combined with GelMA creating a hybrid bioink. This work sets the stage for future hybrid bioinks for muscle biofabrication