Direct-Writing Electrospun Functionalized Scaffolds for Periodontal Regeneration: In Vitro Studies.

Multiphasic scaffolds that combine different architectural, physical, and biological properties are the best option for the regeneration of complex tissues such as the periodontium. Current developed scaffolds generally lack architectural accuracy and rely on multistep manufacturing, which is difficult to implement for clinical applications. In this context, direct-writing electrospinning (DWE) represents a promising and rapid technique for developing thin 3D scaffolds with controlled architecture. The current study aimed to elaborate a biphasic scaffold using DWE based on two polycaprolactone solutions with interesting properties for bone and cement regeneration. One of the two scaffold parts contained hydroxyapatite nanoparticles (HAP) and the other contained the cementum protein 1 (CEMP1). After morphological characterizations, the elaborated scaffolds were assessed regarding periodontal ligament (PDL) cells in terms of cell proliferation, colonization, and mineralization ability. The results demonstrated that both HAP- and CEMP1-functionalized scaffolds were colonized by PDL cells and enhanced mineralization ability compared to unfunctionalized scaffolds, as revealed by alizarin red staining and OPN protein fluorescent expression. Taken together, the current data highlighted the potential of functional and organized scaffolds to stimulate bone and cementum regeneration. Moreover, DWE could be used to develop smart scaffolds with the ability to spatially control cellular orientation with suitable cellular activity at the micrometer scale, thereby enhancing periodontal and other complex tissue regeneration.

Isothermal self-assembly of multicomponent and evolutive DNA nanostructures.

Thermal annealing is usually needed to direct the assembly of multiple complementary DNA strands into desired entities. We show that, with a magnesium-free buffer containing NaCl, complex cocktails of DNA strands and proteins can self-assemble isothermally, at room or physiological temperature, into user-defined nanostructures, such as DNA origamis, single-stranded tile assemblies and nanogrids. In situ, time-resolved observation reveals that this self-assembly is thermodynamically controlled, proceeds through multiple folding pathways and leads to highly reconfigurable nanostructures. It allows a given system to self-select its most stable shape in a large pool of competitive DNA strands. Strikingly, upon the appearance of a new energy minimum, DNA origamis isothermally shift from one initially stable shape to a radically different one, by massive exchange of their constitutive staple strands. This method expands the repertoire of shapes and functions attainable by isothermal self-assembly and creates a basis for adaptive nanomachines and nanostructure discovery by evolution.

Innovative particle standards and long-lived imaging for 2D and 3D dSTORM.

Direct stochastic optical reconstruction microscopy (dSTORM), developed in the last decade, has revolutionised optical microscopy by enabling scientists to visualise objects beyond the resolution provided by conventional microscopy (200 nm). We developed an innovative method based on blinking particle standards and conditions for long-lived imaging over several weeks. Stable localisation precisions within the 10 nm-range were achieved for single virions and in cellulo 2D imaging of centrosomes, as well as their reliable reconstruction in 3D dSTORM.

Improvements in Resolution of Additive Manufacturing: Advances in Two-Photon Polymerization and Direct-Writing Electrospinning Techniques.

In recent years, additive manufacturing (AM) technologies have attracted significant interest in many industrial and research fields, particularly in tissue engineering. Printed structures used as physical and bioactive supports for tissue regeneration are becoming increasingly complex so as to mimic natural tissues in order to answer future medical needs. Reproducing the biological environment of a native tissue from the microscopic to the macroscopic scale appears to be the best strategy for effective regeneration. Recent advances in AM have led to the production of scaffolds designed with a high precision. This Review presents results concerning two AM technologies which enable the highest accuracy of scaffold design to be obtained, with a precision down to the nanoscale. The first technique is based on a two-photon polymerization (TPP) process, while the other is based on a direct-writing electrospinning (DWES) system. Here, we present an overview of the fabrication mechanisms, the final scaffold properties, and their applications in tissue engineering. The production of highly resolved structures offers new possibilities for studying cell behavior in a controlled environment and also for adjusting the desired scaffold properties to address current and future needs in tissue engineering. The current technical limitations and future challenges are thus also discussed in this Review.