Responsive biomaterials for 3D bioprinting: A review

Three-dimensional (3D) bioprinting enables a controlled deposition of cells, biomaterials, and biological compounds (i.e., bioinks) to build complex 3D biological models, biological living systems, and therapeutic products. Developing responsive biomaterials as novel bioinks has been a central focus of research in the field of bioprinting because of their controllable material properties in response to printing-induced external or internal stimuli. In this review, we highlight the most recent advances of responsive biomaterials for 3D bioprinting applications. We review commonly used stimuli-responsive biomaterials and strategies for utilizing multifunctional responsiveness to achieve desirable printability, structural formability, cell viability, and construct bioactivity for 3D bioprinting. We also summarize major bioink formulation strategies currently adopted in 3D bioprinting. We subsequently discuss several promising applications of 3D printing involving responsive biomaterials, such as bioprinting in a supporting bath, 4D bioprinting, and bioprinting new controlled drug delivery systems. Future perspectives on the design and development of novel multifunctional bioinks based on responsive biomaterials and technological innovations are also presented.     

Organ regeneration: integration application of cell encapsulation and 3D bioprinting

3D bioprinting has shown great promise in the field of tissue engineering, which offers a vital and significant platform for organ regeneration. Therefore, an increasing focus on 3D bioprinting, coupled with a growing knowledge of cell–cell interaction and cell encapsulation, has driven researchers to discover the preferable biomaterials that enable the greatest possible to reconstruct artificial organs with the different cells and hydrogel. One important challenge is to adapt materials selected to improve the cell survival rate. In this paper, we firstly summarise the fundamentals and the latest application of biomaterials that have significant characteristics such as porous, biodegradability, biological compatibility, and adaptability, and further describe formation mechanisms of droplet under the different cell encapsulation technologies, and finally highlight integration application of cell encapsulation and 3D bioprinting.     

The Next Frontier of 3D Bioprinting: Bioactive Materials Functionalized by Bacteria

3D bioprinting has become a flexible technical means used in many fields. Currently, research on 3D bioprinting is mainly focused on the use of mammalian cells to print organ and tissue models, which has greatly promoted progress in the fields of tissue engineering, regenerative medicine, and pharmaceuticals. In recent years, bacterial bioprinting has gradually become a rapidly developing research fields, with a wide range of potential applications in basic research, biomedicine, bioremediation, and other field. Here, this works reviews new research on bacterial bioprinting, and discuss its future research direction.     

The Rule of Thirds: Controlling Junction Chirality and Polarity in 3D DNA Tiles

The successful self-assembly of tensegrity triangle DNA crystals heralded the ability to programmably construct macroscopic crystalline nanomaterials from rationally-designed, nanoscale components. This 3D DNA tile owes its “tensegrity” nature to its three rotationally stacked double helices locked together by the tensile winding of a center strand segmented into 7 base pair (bp) inter-junction regions, corresponding to two-thirds of a helical turn of DNA. All reported tensegrity triangles to date have employed $\left(Z+2/3\right)$ turn inter-junction segments, yielding right-handed, antiparallel, “J1” junctions. Here a minimal DNA triangle motif consisting of 3-bp inter-junction segments, or one-third of a helical turn is reported. It is found that the minimal motif exhibits a reversed morphology with a left-handed tertiary structure mediated by a locally-parallel Holliday junction—the “L1” junction. This parallel junction yields a predicted helical groove matching pattern that breaks the pseudosymmetry between tile faces, and the junction morphology further suggests a folding mechanism. A Rule of Thirds by which supramolecular chirality can be programmed through inter-junction DNA segment length is identified. These results underscore the role that global topological forces play in determining local DNA architecture and ultimately point to an under-explored class of self-assembling, chiral nanomaterials for topological processes in biological systems.