This study reports on the production of high-resolution 3D structures of polylactide-based materials via multi-photon polymerization and explores their use as neural tissue engineering scaffolds. To achieve this, a liquid polylactide resin was synthesized in house and rendered photocurable via attaching methacrylate groups to the hydroxyl end groups of the small molecular weight prepolymer. This resin cures easily under UV irradiation, using a mercury lamp, and under femtosecond IR irradiation. The results showed that the photocurable polylactide (PLA) resin can be readily structured via direct laser write (DLW) with a femtosecond Ti:sapphire laser and submicrometer structures can be produced. The maximum resolution achieved is 800 nm. Neuroblastoma cells were grown on thin films of the cured PLA material, and cell viability and proliferation assays revealed good biocompatibility of the material. Additionally, PC12 and NG108-15 neuroblastoma growth on bespoke scaffolds was studied in more detail to assess potential applications for neuronal implants of this material.

No abstract

In this study, we explore the production of well-defined macroscopic scaffolds with two-photon polymerization (2PP) and their use as neural tissue engineering scaffolds. We also demonstrate that these 3D scaffolds can be replicated via soft lithography, which increases production efficiency. Photopolymerizable polylactic acid (PLA) was used to produce scaffolds by 2PP and soft lithography. We assessed the biocompatibility of these scaffolds using an SH-SY5Y human neuronal cell line and primary cultured rat Schwann cells (of direct relevance to the repair of nerve injuries). A Comet assay with SH-SY5Y human neuronal cells revealed minimal DNA damage after washing the photocured material for 7 days in ethanol. Additionally, thin films and 3D scaffolds of the photocured PLA sustained a high degree of Schwann cell purity (99%), enabled proliferation over 7 days and provided a suitable substrate for supporting Schwann cell adhesion such that bi-polar and tri-polar morphologies were observed. Evidence of orthogonally aligned and organized actin thin filaments and the formation of focal contacts were observed for the majority of Schwann cells. In summary, this work supports the use of PLA as a suitable material for supporting Schwann cell growth and in turn use of 3D soft lithography for the synthesis of neural scaffolds in nerve repair.

Catch and release: Bridged silsesquioxanes act as organic–inorganic precursors for nanospheres to encapsulate bioactive molecules for drug‐delivery applications. The nanosystems (see picture) are constructed from an liposomal core containing bioactive molecules and an network shell formed by silica and organic ester fragments that can act as responsive molecular gates.

Cryo-etch scanning electron microscopy (cryo-etch SEM) of aqueous gels composed of colloidal silica nanoparticles in the 1-40 nm range and liposomes of ∼200 nm gave unique morphologies. The aqueous gels are frozen at subcooled liquid nitrogen and fractured to obtain a fresh surface. High-vacuum sublimation of ice from the freshly exposed surface (etching) results in the formation of a hierarchy assembly, characterized by granular fences composed of colloidal silica and liposomes surrounded by empty areas in which amorphous ice originally resided. The biocompatible character of this ice segregation induced self-assembly (ISISA) process that allows for the preservation of the structural integrity of liposomes within the assembly is demonstrated by fluorescence anisotropy performed at the binary colloidal aqueous gels and differential scanning calorimetry and electron microscopy at the hierarchy assembly. The resulting assembly shows an interesting dual character, with one colloidal entity supporting the structure (e.g., silica) and the other providing functionality (e.g., liposomes).