Biofabrication最新文献

Recombinant collagen holds immense potential in the development of medical functional materials, yet its widespread application remains hindered by the absence of a suitable self-assembly strategy. In this article, we report the discovery that the bacterial-derived collagen-like (CL) protein Scl2 can rapidly self-gelation (∼1 min at pH ∼7) due to properties enabled by metal coordination crosslinking. This was achieved by fusing metal ion chelating peptides to both termini of the protein. Our research further reveals the critical role of electrostatic interaction between globular domains (V domains) of recombinant collagen in the self-assembly process. We show that modifying the negative charge load of the N-terminalα-helix of the V domain enables control over the self-assembly time (from 1 min to 30 min) and strength (from 8 kPa to 26 kPa) of the Scl2 hydrogel. By adjusting the molecular weight of the core CL domain, we have remarkably further enhanced the strength of the Scl2 hydrogel to 78 kPa. Moreover, we innovatively employed electro-oxidized tea polyphenols to enhance the stability of the Scl2 hydrogel, resulting in the formation of a reliable self-assembled metal coordination hydrogel at physiological temperature. This approach not only eliminates the need for toxic chemical crosslinking agents but also confers the material with multiple functionalities, such as adhesion, antibacterial, and antioxidant properties. The novel recombinant Scl2 hydrogel exhibited exceptionalin situself-gelation and injectable properties. This innovative hydrogel not only demonstrates remarkable biological activity but also exhibits remarkable tissue repair-promoting capabilities in full-thickness skin injury models (shorten healing cycle by more than 30%). The convenient and versatile nature of this recombinant collagen hydrogel makes it promising for clinical applications in injury treatment, demonstrating broad applications in the future.

In modern agriculture, nanotechnology was recognized as a potentially transformative innovation. Nanopolymers as coating matrix in nano-biofertilizer has a massive impact on agricultural productivity. The integration of nanotechnology with biofertilizers has led to the creation of nano-biofertilizer formulations that enhance nutrient delivery, improve plant growth, and increase resistance to environmental stress. Nanopolymers, both synthetic and biogenic, including chitosan, cellulose, gelatin, sodium alginate, starch, and polyvinyl alcohol, are utilized as encapsulating materials. They are effective in ensuring controlled nutrient release and shielding beneficial microorganisms from external environmental conditions. Studies indicate that nano-biofertilizers improve soil quality, raise crop yields, and reduce the usage of chemical fertilizers to enhance sustainable agricultural practices. The review also addresses the microbial encapsulation methodology, release kinetics, phytotoxicity, challenges and future prospects of nano-biofertilizer technology, including nanoparticle-bacteria interaction, scalability, and regulatory considerations. This paper elaborates the potential and limitations of nano-biofertilizers, providing insights for future advancements in the agriculture field.

Kidney diseases are among the leading causes of death globally. With the increasing rates of acute kidney injury (AKI) requiring hospitalisation, a better understanding of pathophysiological mechanisms is needed to treat the patients more efficiently. Nephrotoxicity is one of the most common causes of AKI, mainly due to the high availability of over-the-counter drugs and natural supplements, which may interact with prescribed drugs at the level of pharmacokinetics, among other factors. The latter can lead to clinically relevant complications (including AKI), which is even more pronounced given the increasingly ageing population in the Western world and the associated increase in polypharmacy. Drug testing starts at the preclinical level, where a reliable model is needed to predict human response to a tested drug with sufficient accuracy. Recently,in-vitrokidney models of different complexities have been created to study various aspects of kidney diseases. Because the proximal tubule plays a vital role in several mechanisms, many models include proximal tubular epithelial cells (PTECs). Monocultures of PTECs do not representin-vivotissue accurately enough. Therefore, more complex models with more cell types are being built. To our knowledge, this is the first review focusing on co-culture models and cell types used alongside PTECs for studying the nephrotoxicity of drugs and other mechanisms of AKI and chronic kidney disease.

The recent occurrence of the Covid-19 pandemic and frequent wildfires have worsened pulmonary diseases and raised the urgent need for investigating host-pathogen interactions and advancing drug and vaccine therapies. Historically, research and experimental studies have relied on two-dimensional cell culture dishes and/or animal models, which suffer from physiological differences from the human lung. More recently, there has been investigation into the use of lung-on-a-chip models and organoids, while the use of bioprinting technologies has also emerged to fabricate three-dimensional constructs or lung models with enhanced physiological relevance. Concurrently, achievements have also been made to develop biomimetic strategies for simulating thein vivobiomechanical conditions induced by lung breathing, though challenges remain with incorporating these strategies with bioprinted models. Bioprinted models combined with advanced biomimetic strategies would represent a promising approach to advance disease discovery and therapeutic development. As inspired, this article briefly reviews the recent progress of both bioprintedin vitrolung models and biomechanical strategies, with a focus on native lung tissue microstructure and biomechanical properties, bioprinted constructs, and biomimetic strategies to mimic the native environment. This article also urges that the integration of bioprinting advances and biomimetic strategies would be essential to achieve synergistic effects forin vitrolung modelling. Key issues and challenges are also identified and discussed along with recommendations for future research.

Artificial bone graft stands out for avoiding limited source of autograft as well as susceptibility to infection of allograft, which makes it a current research hotspot in the field of bone defect repair. However, traditional design and manufacturing method cannot fabricate bone scaffold that well mimics complicated bone-like shape with interconnected porous structure and multiple properties akin to human natural bone. Additive manufacturing, which can achieve implant's tailored external contour and controllable fabrication of internal microporous structure, is able to form almost any shape of designed bone scaffold via layer-by-layer process. As additive manufacturing is promising in building artificial bone scaffold, only combining excellent structural design with appropriate additive manufacturing process can produce bone scaffold with ideal biological and mechanical properties. In this article, we sum up and analyze state of art design and additive manufacturing methods for bone scaffold to realize shape/properties collaborative intelligent manufacturing. Scaffold design can be mainly classified into design based on unit cells and whole structure, while basic additive manufacturing and 3D bioprinting are the recommended suitable additive manufacturing methods for bone scaffold fabrication. The challenges and future perspectives in additive manufactured bone scaffold are also discussed.

In this present study, we introduce an innovative hybrid 3D bioprinting methodology that integrates fused deposition modeling (FDM) with top-down digital light processing (DLP) for the fabrication of an artificial trachea. Initially, polycaprolactone (PCL) was incorporated using an FDM 3D printer to provide essential mechanical support, replicating the structure of tracheal cartilage. Subsequently, a chondrocyte-laden glycidyl methacrylated silk fibroin hydrogel was introduced via top-down DLP into the PCL scaffold (PCL-Sil scaffold). The mechanical evaluation of PCL-Sil scaffolds showed that they have greater flexibility than PCL scaffolds, with a higher deformation rate (PCL-Sil scaffolds: 140.9% ± 5.37% vs. PCL scaffolds: 124.3% ± 6.25%) and ability to withstand more force before fracturing (3.860 ± 0.140 N for PCL-Sil scaffolds vs. 2.502 ± 0.126 N for PCL scaffolds, ***P< 0.001). Both types of scaffolds showed similar axial compressive strengths (PCL-Sil scaffolds: 4.276 ± 0.127 MPa vs. PCL scaffolds: 4.291 ± 0.135 MPa). Additionally, PCL-Sil scaffolds supported fibroblast proliferation, indicating good biocompatibility.In vivotesting of PCL-Sil scaffolds in a partial tracheal defect rabbit model demonstrated effective tissue regeneration. The scaffolds were pre-cultured in the omentum for two weeks to promote vascularization before transplantation. Eight weeks after transplantation into the animal, bronchoscopy and histological analysis confirmed that the omentum-cultured PCL-Sil scaffolds facilitated rapid tissue regeneration and maintained the luminal diameter at the anastomosis site without signs of stenosis or inflammation. Validation study to assess the feasibility of our hybrid 3D bioprinting technique showed that structures, not only the trachea but also the vertebral bone-disc and trachea-lung complex, were successfully printed.

In this research, carboxymethyl cellulose (CMC)/gelatin (Gel)/graphene oxide (GO)-based scaffolds were produced by using extrusion-based 3D printing for cardiac tissue regeneration. Rheological studies were conducted to evaluate the printability of CMC/Gel/GO inks, which revealed that CMC increased viscosity and enhanced printability. The 3D-printed cardiac patches were crosslinked with N-(3-dimethylaminopropyl)-n'-ethylcarbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) (100:20 mM, 50:10 mM, 25:5 mM) and then characterized by mechanical analysis, electrical conductivity testing, contact angle measurements and degradation studies. Subsequently, cell culture studies were conducted to evaluate the viability of H9C2 cardiomyoblast cells by using the Alamar Blue assay and fluorescence imaging. A high concentration of EDC/NHS (100:20 mM) led to the stability of the patches; however, it drastically reduced the flexibility of the scaffolds. Conversely, a concentration of 25:5 mM resulted in flexible but unstable scaffolds in phosphate buffer saline solution. The suitable EDC/NHS concentration was found to be 50:10 mM, as it produced flexible, stable, and stiff cardiac scaffolds with high ultimate tensile strength. Mechanical characterization revealed that % strain at break of C15/G7.5/GO1 exhibited a remarkable increase of 61.03% compared to C15/G7.5 samples. The improvement of flexibility was attributed to the hydrogen bonding between CMC, Gel and GO. The electrical conductivity of 3D printed CMC/Gel/GO cardiac patches was 7.0 × 10^-3S cm^-1, demonstrating suitability for mimicking the desired electrical conductivity of human myocardium. The incorporation of 1 wt% of GO and addition of CMC concentration from 7.5 wt% to 15 wt% significantly enhanced relative % cell viability. Overall, although this research is at its infancy, CMC/Gel/GO cardiac patches have potential to improve the physiological function of cardiac tissue.

Engineered neural tissue (EngNT) is a stabilised aligned cellular hydrogel that offers a potential alternative to the nerve autograft for the treatment of severe peripheral nerve injury. This work aimed to automate the production of EngNT, to improve the feasibility of scalable manufacture for clinical translation. Endothelial cells were used as the cellular component of the EngNT, with the formation of endothelial cell tube-like structures mimicking the polarised vascular structures formed early on in the natural regenerative process. Gel aspiration-ejection for the production of EngNT was automated by integrating a syringe pump with a robotic positioning system, using software coded in Python to control both devices. Having established the production method and tested mechanical properties, the EngNT containing human umbilical vein endothelial cells (EngNT-HUVEC) was characterised in terms of viability and alignment, compatibility with neurite outgrowth from rat dorsal root ganglion neurons and formation of endothelial cell networksin vitro. EngNT-HUVEC manufactured using the automated system contained viable and aligned endothelial cells, which developed into a network of multinucleated endothelial cell tube-like structures inside the constructs and an outer layer of endothelialisation. The EngNT-HUVEC constructs were made in various sizes within minutes. Constructs provided support and guidance to regenerating neuritesin vitro. This work automated the formation of EngNT, facilitating high throughput manufacture at scale. The formation of endothelial cell tube-like structures within stabilised hydrogels provides an engineered tissue with potential for use in nerve repair.

In the body, capillary beds fulfill the metabolic needs of cells by acting as the sites of diffusive transport for vital gasses and nutrients. In artificial tissues, replicating the scale and complexity of capillaries has proved challenging, especially in a three-dimensional context. In order to better develop thick artificial tissues, it will be necessary to recreate both the form and function of capillaries. Here we demonstrate a top-down method of patterning hydrogels using sacrificial templates formed from thermoresponsive microfibers whose size and architecture approach those of natural capillaries. Within the resulting microchannels, we cultured endothelial monolayers that remain viable for over three weeks and exhibited functional barrier properties. Additionally, we cultured endothelialized microchannels within hydrogels containing fibroblasts and characterized the viability of the co-cultures to demonstrate this approach's potential when applied to cell-laden hydrogels. This method represents a step forward in the evolution of artificial tissues and a path towards producing viable capillary-scale microvasculature for engineered organs.

In embedded 3D printing (EMB3D), a nozzle extrudes continuous filaments inside of a viscoelastic support bath. Compared to other extrusion processes, EMB3D enables softer structures and print paths that conform better to the shape of the part, allowing for complex structures such as tissues and organs. However, strategies for high-quality dimensional accuracy and mechanical properties remain undocumented in EMB3D. This work uses computational fluid dynamics simulations in OpenFOAM to probe the underlying physics behind two processes: deformation of the printed part due to nearby nozzle motion and fusion between neighboring filaments during printing. Through simulations, we disentangle yielding from viscous dissipation, and we isolate interfacial tension effects from rheology effects, which are difficult to separate in experiments. Critically, these simulations find that disturbance and fusion are controlled by the flow of support fluid around the nozzle. To avoid part deformation, the nozzle must remain far from existing parts during non-printing moves, moreso when traveling next to the part than above the part and especially when the interfacial tension between the ink and support is non-zero. Additionally, because support can become trapped between filaments at zero interfacial tension, the spacing between filaments must be tight enough to produce over-printing, or printing too much material for the designed space. In non-Newtonian fluids, spacings for vertical walls must be even tighter than spacings for horizontal planes. At these spacings, printing a new filament sometimes creates and sometimes mitigates shape defects in the old filament. While non-zero ink-support interfacial tensions produce better inter-filament fusion than zero interfacial tension, interfacial tension also produces shape defects. Slicing algorithms that consider these unique EMB3D defects are needed to improve mechanical properties and dimensional accuracy of bioprinted constructs.