Tumors, trauma, and congenital defects require volume restoration of soft tissues. Tissue engineering provides an alternative source for substituting these defects. Cell encapsulation into hydrogels provides a three-dimensional microenvironment. Spheroids of cells provide close packing and increase cell-to-cell contacts resulting in differentiation. Gelatin is a natural polymer with low immunogenicity and preserved amino acid motifs for cell adhesion and proliferation. In the present study, a soft photo-crosslinked gelatin methacrylate (GelMA) hydrogel with long in vitro lifetime was synthesized. Stem cells (dental pulp derived, DPSC) and endothelial cells (umbilical cord derived, HUVEC) were formed into spheroids to induce prevascular network formation and encapsulated into GelMA (10% weight/volume). Results showed high cell viability, better gel mechanical properties, and longer HUVEC sprouting with spheroids compared to the same combination of cells. Altogether, the photo-crosslinked GelMA hydrogels with DPSC and HUVEC spheroids provided a promising tissue engineering and vascularization strategy in vitro.

The cellular accumulation of drug delivery systems (DDSs) is a critical parameter to determine the final outcome of cancer chemotherapy. Herein, we designed a red blood cells membrane-based vehicle (RV) and employed it to load both doxorubicin (Dox) and IR 780 (RV/I-D). The photothermal-assisted chemotherapy efficacy of RV/I-D on the treatment of cancer was tested on a prostate cancer model. Excitingly, the results showed that RV/I-D was stable and safe nanoparticles with size at about 100 nm. Moreover, upon the increase of system temperature using photothermal effects of IR780, the drug release of the DDS was accelerated. Above all, the DDS also increased the accumulation of drugs into the Dox-resistant prostate cancer cells (PC-3/Dox) both in vitro and in vivo and showed enhanced anticancer performance.

The materials chosen to make thermal engines, spacecrafts, or human implants cannot fail in an unpredictable way to guarantee the users' well-being. These applications can benefit from the use of ceramics because of their temperature resistance, corrosion resistance, or hardness. Although parts based on ceramic matrix composites and zirconia are already in use, a more recent ceramic with a structure inspired from seashells provides an attractive combination of ease of processing, high strength, and high toughness. These nacre-like aluminas are made of aligned micron-sized monocrystalline platelets joined together by a mix of mineral secondary phase and nanoparticles. The review's first objective is to provide a picture of what these newly developed bioinspired ceramics are capable of within today's ceramic and nacre-inspired composites landscape. I will also extract from the results the links between process/microstructure/performance to better understand the potential of these materials in terms of toughness and strength increase. Finally, I will present the challenges that are ahead to eventually reproduce the exceptional fracture behavior observed in nacre.

Articular cartilage plays an important role in synovial joint function, but this function is diminished when cartilage tissue breaks down in osteoarthritis. Tissue engineering is a promising approach for replacing failed cartilage, as cartilage is a relatively simple tissue with no blood supply and very few biological cells. To imitate the structure of natural cartilage extracellular matrix material, three components must be included: the hydrated ground substance, the charges that contribute to compressive stiffness via electrostatic repulsion, and the nanofibrous collagen network that resists tensile deformation and failure. Here, the nanofiber network is considered, with examination of its fracture behavior in an as-electrospun state and following a mild chemical crosslinking process. Mode III fracture testing was used to quantify the tear toughness of the fibrous mats, and failure behavior was qualitatively examined with scanning electron microscopy. In ongoing work, this nanofibrous structure will be combined with a charged polyelectrolyte hydrogel gel to create a biomimetic cartilage-like material. By using biomimicry to replicate what is present in native cartilage tissue, a superior material can be designed and fabricated for use in tissue repair and replacement.

Nature is ripe with biological organisms that can interact with its surroundings to continuously morph their surface texture. Many attempts have been made to optimize artificial surfaces depending on operational needs; however, most of these architected materials only focus on enhancing a specific material property or functionality. This study introduces a new class of instability-induced morphable structures, herein referred to as “Active Skins”, which enables on-demand, reversible, surface morphing through buckling-induced feature deployment. By taking advantage of a preconceived auxetic unit cell geometrical design, mechanical instabilities were introduced to facilitate rapid out-of-plane deformations when in-plane strains are applied. Here, these notches were introduced at judiciously chosen locations in an array of unit cells to elicit unique patterns of out-of-plane deformations to pave way for controlling bulk Active Skin behavior. These purposefully designed imperfections were employed for selectively actuating them for applications ranging from camouflage to surface morphing to soft robotic grippers.

The deficient disposition of the pruning waste, from grass (Poaceae), has been converted into a considerable environmental problem since it is discarded in common garbage dumps. As a result, gases and lixiviates are generated producing a negative impact on the environment. This project takes advantage of these residues to isolate their chloroplasts, with the aim of subsequently developing bioreactors that absorb CO2. The encapsulation of grass chloroplasts into silica monolith with a hierarchical texture, using high internal phase emulsion (HIPE) method was carried out. The isolated chloroplasts were analysed by UV-Vis spectroscopy to estimate the amount of chlorophylls a and b present in the grass. Moreover, the synthesized samples were characterized by fluorescence spectroscopy for monitoring their photosynthetic activity, having an activity up to at least 90 days.

Small angle neutron scattering (SANS) and dynamic light scattering (DLS) measurements were made on near physiological solutions of a bottlebrush shape polyelectrolyte, aggrecan. Aggrecan is a biologically important molecule whose complexes with hyaluronic acid (HA) provide the osmotic resistance of cartilage. We have investigated the effect of complexation of aggrecan with HA on the structure and dynamic properties of aggrecan solutions. SANS reveals that the supramolecular structure of aggrecan assemblies is only marginally affected by the HA. DLS indicates that the dynamic response of the aggrecan-HA complex is slower than that of the corresponding aggrecan solution. However, addition of calcium ions slightly increases the relaxation rate of the autocorrelation function of the aggrecan solution.

Bioelectronics requires versatile, efficient, and low-cost interfaces between the biological entities and the conductive unit. Conductive polymers represent a valid choice to assemble such interfaces able to extract or impinge charges between the biological units and the conductive electronic systems. A drawback in the use of such systems is that the polymerization reaction often takes place in environments whose chemical and physical characteristics clash with the mild conditions required for living biological systems. In the present work, we successfully prove that the conductive polymer poly(gallic acid) can be synthesized in medium designed for bacterial growth, characterised by the presence of several adverse conditions including numerous chemicals, high ionic strength, and almost neutral pH. The gallic acid successfully polymerizes within few hours and with a 40% yield, by exploiting the catalytic activity of the enzyme laccase from the polypore mushroom Trametes versicolor. The resulting polymer is characterised by absorption and Nuclear Magnetic Resonance spectroscopies. The viability of Rhodobacter sphaeroides culture, assessed via the coffee-ring technique, shows an important, but not complete detrimental effect of the gallic acid on the bacterial growth.

Multifunctional biopolymer-based materials are promising candidates for next generation regenerative biomaterials. Understanding the degradation behavior of biomaterials is vital for ensuring biological safety, as well as for better control of degradation properties based on rational design of a material’s physical and chemical characteristics. In this study, we decipher the degradation of a hydrogel prepared from gelatin and lysine diisocyanate ethyl ester (LDI) using in vitro models, which simulate hydrolytic, oxidative and enzymatic degradation (collagenase). Gravimetrical, morphological, mechanical and chemical properties were evaluated. Notably, the hydrogels were relatively resistant to hydrolytic degradation, but degraded rapidly within 21 days (>95% mass loss) under oxidative and collagenase degradation. Oxidative and collagenase degradation rapidly decreased the storage and loss modulus of the hydrogels, and slightly increased their viscous component (tan δ). For each degradation condition, the results suggest different possible degradation pathways associated to the gelatin polypeptide backbone, urea linkages and ester groups. The primary degradation mechanisms for the investigated gelatin based hydrogels are oxidative and enzymatic in nature. The relative hydrolytic stability of the hydrogels should ensure minimal degradation during storage and handling prior to application in surgical theatres.

Energy-efficient condensation of steam contained in atmospheric air has emerged as a solution to the water scarcity. Academic and industrial research works that seeks to develop water collection devices with high efficiency has great relevance for the scientific community. In this work, we aim to show that modified carbon nanotubes forest can remove the condensed drops easier than a hydrophobic and a super-hydrophilic surface. In addition, this result was reached at high super saturation level which is an innovative aspect of this work. The Vertically Aligned Carbon Nanotubes (VACNTs) were grown on steel pipes. We used a CO2 laser and an O2 plasma to perform the post treatments that changed the CNTs to super-hydrophobic and super-hydrophilic, respectively. In addition, the CO2 laser treatment added a second level of roughness in the surface by etching the nanotubes walls. A polyethylene coating attached the carbon nanotubes to the substrate. We experimentally demonstrated a 24% higher vapor condensation rate at high supersaturations levels.

There is widespread research and popular interest in developing micro-invasive neural interfacing modalities. An increasing variety of probes have been developed and reported in the literature. Newer, smaller probes show significant benefit over larger ones in reducing tissue damage and scarring. A different set of obstacles arise, however, as probes become smaller. These include reliable insertion and robustness. This review articulates the impact of various design parameters (material, geometry, size) on probe insertion mechanisms, chronic viability, and glial scarring. We highlight various emerging technologies utilizing novel form factors including micron-scale interfaces and bio-inspired designs for probe insertion and steering.

Nanocomposites comprising of biopolymers and calcium phosphate cements (CaP) are promising due to their biocompatibility, non-toxicity, biodegradability and suitable mechanical properties for biomedical applications. In here, a new composite material was synthesized with carboxymethylcellulose (CMC) and gelatin (GEL) as the liquid phase and CaP based powder as the solid phase. In this study, the effect of addition of different wt% of GEL including 0, 5, 10, 20 in the liquid phase was investigated on the physical properties of the nanocomposites. Physico-chemical characteristics of materials were determined by using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and mechanical tests. Swelling analysis was performed after 1, 8, 16, 24 and 48 hours and degradation of samples was studied after 7 and 14 days. FTIR results showed that there was physical interaction between CMC and GEL with H bonding which was evident from the peak at 3288cm-1. Disruption in GEL structure was observed from the band at 1600-1400 cm-1 Disruption of GEL structure may increase the interaction between CMC and GEL molecules. After mixing of solid and liquid phases, negative charged COO- groups on CMC and Ca2+ molecules from CaP start to interact with each other. This produces attraction sites for PO43- molecules. This lead to accumulation of hydroxyapatite-like structures. A homogenous and porous microstructure was observed by using SEM in all samples. Mechanical tests showed that GEL improved the strength of the samples up to 20 wt% of GEL. The addition of 20 wt% of GEL decreased the mechanical properties. The compressive strength values were found up to approximately 6 MPa. Swelling results revealed that increasing in GEL concentration cause decrease in swelling until the 16th hour, after that 10wt% GEL samples had the lowest swelling which was approximately 28%. Finally, degradation studies indicated that the highest degradation rate was for 10% GEL incorporated samples. Addition of further GEL also reduced the degradation rate. Overall, the addition of GEL improved physical properties of the samples for potential biomedical applications.

Prostate cancer has a strong preference for metastasizing to bone which is the primary cause of prostate cancer-related morbidity and mortality. The complex nature of cancer metastasis requires the development of translational models that recapitulate a specific metastatic stage. Herein, we report the mimicking of mesenchymal to epithelial transition (MET) of prostate cancer cells using highly metastatic and a non-metastatic prostate cancer cell lines. A unique cell culture technique that we termed as ‘sequential culture’ was used to create a biomimetic bone microenvironment for metastasized prostate cancer cells by introducing bioactive factors from osteogenic induction of human mesenchymal stem cells (MSCs) within the porous 3D scaffolds. The in vitro 3D tumor model can be used as a testbed to study the interaction between prostate cancer and bone microenvironment and for the design of novel therapeutic studies.

In recent decades, increasing research interest has shifted from traditional rigid skeleton robotics to flexible, shape-programmable, environmentally adaptive and stimuli-responsive “soft robotics”. Within this discipline, soft-robots capable of untethered and/or remote-controlled operation are of particular interest given their utility for actuation in complex situations with larger range of mobility and higher degrees of freedom. The use of new materials and the development of advanced fabrication techniques enable better performance and expand the utility of such soft actuators, moving them towards real-world applications. This review outlines some recent advances in untethered soft robotics and actuators to illustrate the promise of these applications at the interface of material science and device engineering.

We present a new class of bioinspired nanomaterials that are stabilized by a combination of covalent and hydrogen bonds. Prior work by others has shown that cyclic peptides can self-assemble to form supramolecular assemblies through backbone-backbone hydrogen bonding. To improve upon this molecular architecture, we develop a synthesis route to polymerize cyclic peptides and form a linear polymer chain that can transition between a rigid nanorod and an unfolded conformation. For a cyclic peptide polymer containing amine-terminated side chains on each ring, we demonstrate self-assembly can be triggered in aqueous solutions by varying the pH. We measure the elastic modulus of the rigid nanorods to be ca. 50 GPa, which is comparable to our molecular dynamics (MD) prediction (ca. 64 GPa). Our results highlight the uniqueness of our molecular architecture, namely their exemplary toughness (up to 3 GJ m-3), in comparison to other cyclic peptide-based assemblies. Finally, we demonstrate amphiphilic cyclic β-peptides are capable of inhibiting the growth of gram-negative and gram-positive bacteria.

We synthesized precision oligomers of thiophene with cationic and hydrophobic side chains to mimic the charge, hydrophobicity, and molecular size of antibacterial host defense peptides (HDPs). In this study, the source of cationic charge was a guanidinium salt moiety intended to reflect the structure of arginine-rich HDPs. Due to the pi-conjugated oligo(thiophene) backbone structure, these compounds absorb visible light in aqueous solution and react with dissolved oxygen to produce highly biocidal reactive oxygen species (ROS). Thus, the compounds exert bactericidal activity in the dark with dramatically enhanced potency upon visible light illumination. We find that guanylation of primary amine groups enhanced the activity of the oligomers in the dark but also mitigated their light-induced activity enhancement. In addition, we also quantified their toxicity to mammalian cell membranes using a hemolysis assay with red blood cells, in the light and dark conditions.

Sunlight is the most environmental friendly energy source available on Earth; many efforts devoted to design artificial photoconversion systems are ongoing, nevertheless they are still expensive and poorly efficient. Photoconversion devices made with organic-biological hybrids, or biohybrids, based on the photosynthetic reaction center (RC) have been introduced. In these systems, the photoenzyme is garnished with artificial antennas to enhance the photoactivity of the RC. Here we present a newly synthesized heptamethine cyanine dye that fulfills requisites to act as efficient RC light harvesting antenna.

This work aims at providing guidance through systematic experimental characterization for the design of 3D-printed scaffolds for potential orthopedic applications, focusing on fused deposition modeling with a composite of clinically available polycaprolactone (PCL) and β-tricalcium phosphate (β-TCP). First, we studied the effect of the chemical composition (0–60% β-TCP/PCL) on the scaffold’s properties. We showed that surface roughness and contact angle were, respectively, proportional and inversely proportional to the amount of β-TCP and that degradation rate increased with the amount of ceramic. Biologically, the addition of β-TCP enhanced proliferation and osteogenic differentiation of C3H10. Second, we systematically investigated the effect of the composition and the porosity on the 3D-printed scaffold mechanical properties. Both an increasing amount of β-TCP and a decreasing porosity augmented the apparent Young’s modulus of the 3D-printed scaffolds. Third, as a proof of concept, a novel multimaterial biomimetic implant was designed and fabricated for potential disc replacement.

The holy grail of regenerative technologies is to regrow a limb. This grand challenge requires us to develop truly innovative strategies and toolboxes across advanced materials science, stem cell science, physics, and developmental biology, and converge these advancements to address the limitations of wound healing and harness the regenerative capacity in humans. We discuss the convergence approach put forward by the field of regenerative engineering to develop translational strategies involving electrically conductive and novel polymers, stem cells, high-throughput technologies, and nanotechnology to regenerate the limb.

The increasing demands on renewable energy nowadays caused the development of marine current turbine industry. In order to improve the current design of marine current turbines, studies were conducted to analyse their hydrodynamic performances during operation. Since most of the time marine current turbines operate in arrays, it is important to understand the interactions between the turbines in order to design the optimum turbine farm. OpenFOAM® was used to simulate the turbine interactions of conventional and biomimetic marine current turbines in tandem configuration. The conventional marine current turbines were referred to Pinon et al. (2012) and Mycek et al. (2013) while the biomimetic marine current turbine was adopted from Chu (2016). The numerical simulations were conducted with turbines in different inter-device distances, A/D. The percentage differences of ‘‘efficiency’’, η between the IFREMER-LOMC and the biomimetic turbine case of inter-device distances, A/D = 4, 6, 8 and 10 are 14.3%, 6.4%, 3% and 1.92% respectively. The results show that the power produced by the biomimetic turbines in tandem is comparable with the IFREMER-LOMC turbines when A/D > 4. The biomimetic marine current turbines can be a fair choice due to their potential to have alternative fabrication method of their sheet-like turbine blades.