One significant drawback of existing bioprinted tissues is their lack of shelf-availability caused by complications in both fabrication and storage. Here, we report a unique cryobioprinting strategy for simultaneously fabricating and storing cell-laden volumetric tissue constructs through seamlessly combining extrusion bioprinting and cryopreservation. The cryobioprinting performance was investigated by designing, fabricating, and storing cell-laden constructs made of cryoprotective bioinks using a freezing plate with precisely controllable temperature. The in situ freezing process further promoted the printability of cell-laden hydrogel bioinks to achieve freeform structures otherwise inconvenient with direct extrusion bioprinting. The effects of bioink composition on printability and cell viability were evaluated. The functionality of the method was finally investigated using cell differentiation and chick ex ovo assays. The results confirmed the feasibility and efficacy of cryobioprinting as a single-step method for concurrent tissue biofabrication and storage.

Here is the link to our publication in Matter.

Bioprinting, within the emerging field of biofabrication, aims at the fabrication of functional biomimetic constructs. Different 3D bioprinting techniques have been adapted to bioprint cell-laden bioinks. However, single-material bioprinting techniques oftentimes fail to reproduce the complex compositions and diversity of native tissues. Multi-material bioprinting as an emerging approach enables the fabrication of heterogeneous multi-cellular constructs that replicate their host microenvironments better than single-material approaches. Here, bioprinting modalities are reviewed, their being adapted to multi-material bioprinting is discussed, and their advantages and challenges, encompassing both custom-designed and commercially available technologies are analyzed. A perspective of how multi-material bioprinting opens up new opportunities for tissue engineering, tissue model engineering, therapeutics development, and personalized medicine is offered.

Here is the link to our publication in Advanced Materials.

Extrusion-based three-dimensional (3D) printing is an emerging technology for the fabrication of complex structures with various biological and biomedical applications. The method is based on the layer-by-layer construction of the product using a printable ink. The material used as the ink should possess proper rheological properties and desirable performances. Composite materials, which are extensively used in 3D printing applications, can improve printability and offer superior performances for printed constructs. Herein, we review composite inks with a focus on composite hydrogels. The properties of different additives including fibers and nanoparticles are discussed. The performances of various composite inks in biological and biomedical systems are delineated through analyzing the synergistic effects between the composite ink components. Different applications, including tissue engineering, tissue model engineering, soft robotics, and four-dimensional printing, are selected to demonstrate how 3D-printable composite inks are exploited to achieve various desired functionality. This review finally presents an outlook of future perspectives on the design of composite inks.

Here is the link to our publication in ACS Biomaterials Science & Engineering.

Injectable hydrogels are increasingly used for in situ tissue regeneration and wound healing. Ideally, an injectable implant should promote the recruitment of cells from the surrounding native tissue and allow cells to migrate freely as they generate a new extracellular matrix network. Nanocomposite hydrogels such as carbon nanotube (CNT)-loaded hydrogels have been hypothesized to promote cell recruitment and cell migration relative to unloaded ones. To investigate this, CNT-glycol chitosan hydrogels were synthesized and studied. Chemoattractant-induced cell migration was studied using a modified Boyden Chamber experiment. Migrated cells were counted using flow cytometry. Cell adhesion was inferred from the morphology of the cells via an image segmentation method. Cell migration and recruitment results confirmed that small concentrations of CNT significantly increase cell migration in hydrogels, thereby accelerating tissue regeneration and wound healing in situations where there is insufficient migration in the unloaded matrix.

Here is the link to our publication in Scientific Reports.

Porous composite hydrogels were prepared using glycol chitosan as the matrix, glyoxal as the chemical crosslinker, and carbon nanotubes (CNTs) as the fibers. Both carboxylic and hydroxylic functionalized CNTs were used. The homogeneity of CNTs dispersion was evaluated using scanning electron microscopy. Human vocal fold fibroblasts were cultured and encapsulated in the composite hydrogels with different CNT concentrations to quantify cell viability. Rheological tests were performed to determine the gelation time and the storage modulus as a function of CNT concentration. The gelation time tended to decrease for low concentrations and increase at higher concentrations, reaching a local minimum value. The storage modulus obeyed different trends depending on the functional group. The porosity of the hydrogels was found to increase by 120% when higher concentrations of carboxylic CNTs were used. A high porosity may promote cell adhesion, migration, and recruitment from the surrounding native tissue, which will be investigated in a future work aiming at applying this injectable biomaterial for vocal fold tissue regeneration.

Here is the link to our publication in Materials Science and Engineering: C.