3 research outputs found
Nonswelling ThiolâYne Cross-Linked Hydrogel Materials as Cytocompatible Soft Tissue Scaffolds
A key drawback of hydrogel materials for tissue engineering applications
is their characteristic swelling response, which leads to a diminished
mechanical performance. However, if a solution can be found to overcome
such limitations, there is a wider application for these materials.
Herein, we describe a simple and effective way to control the swelling
and degradation rate of nucleophilic thiolâyne polyÂ(ethylene
glycol) (PEG) hydrogel networks using two straightforward routes:
(1) using multiarm alkyne and thiol terminated PEG precursors or (2)
introducing a thermoresponsive unit into the PEG network while maintaining
their robust mechanical properties. In situ hydrogel materials were
formed in under 10 min in PBS solution at pH 7.4 without the need
for an external catalyst by using easily accessible precursors. Both
pathways resulted in strong tunable hydrogel materials (compressive
strength values up to 2.4 MPa) which could effectively encapsulate
cells, thus highlighting their potential as soft tissue scaffolds
Controlling the Size of Two-Dimensional Polymer Platelets for Water-in-Water Emulsifiers
A wide range of biorelevant
applications, particularly in pharmaceutical
formulations and the food and cosmetic industries, require the stabilization
of two water-soluble blended components which would otherwise form
incompatible biphasic mixtures. Such water-in-water emulsions can
be achieved using Pickering stabilization, where two-dimensional (2D)
nanomaterials are particularly effective due to their high surface
area. However, control over the shape and size of the 2D nanomaterials
is challenging, where it has not yet been possible to examine chemically
identical nanostructures with the same thickness but different surface
areas to probe the size-effect on emulsion stabilization ability.
Hence, the rationale design and realization of the full potential
of Pickering water-in-water emulsion stabilization have not yet been
achieved. Herein, we report for the first time 2D polyÂ(lactide) platelets
with tunable sizes (with varying coronal chemistry) and of uniform
shape using a crystallization-driven self-assembly methodology. We
have used this series of nanostructures to explore the effect of 2D
platelet size and chemistry on the stabilization of a water-in-water
emulsion of a polyÂ(ethylene glycol) (PEG)/dextran mixture. We have
demonstrated that cationic, zwitterionic, and neutral large platelets
(ca. 3.7 Ă 10<sup>6</sup> nm<sup>2</sup>) all attain smaller
droplet sizes and more stable emulsions than their respective smaller
platelets (ca. 1.2 Ă 10<sup>5</sup> nm<sup>2</sup>). This series
of 2D platelets of controlled dimensions provides an excellent exemplar
system for the investigation of the effect of just the surface area
on the potential effectiveness in a particular application
Thermoplastic Polyurethane:Polythiophene Nanomembranes for Biomedical and Biotechnological Applications
Nanomembranes
have been prepared by spin-coating mixtures of a polythiophene (P3TMA)
derivative and thermoplastic polyurethane (TPU) using 20:80, 40:60,
and 60:40 TPU:P3TMA weight ratios. After structural, topographical,
electrochemical, and thermal characterization, properties typically
related with biomedical applications have been investigated: swelling,
resistance to both hydrolytic and enzymatic degradation, biocompatibility,
and adsorption of type I collagen, which is an extra cellular matrix
protein that binds fibronectin favoring cell adhesion processes. The
swelling ability and the hydrolytic and enzymatic degradability of
TPU:P3TMA membranes increases with the concentration of P3TMA. Moreover,
the degradation of the blends is considerably promoted by the presence
of enzymes in the hydrolytic medium, TPU:P3TMA blends behaving as
biodegradable materials. On the other hand, TPU:P3TMA nanomembranes
behave as bioactive platforms stimulating cell adhesion and, especially,
cell viability. Type I collagen adsorption largely depends on the
substrate employed to support the nanomembrane, whereas it is practically
independent of the chemical nature of the polymeric material used
to fabricate the nanomembrane. However, detailed microscopy study
of the morphology and topography of adsorbed collagen evidence the
formation of different organizations, which range from fibrils to
pseudoregular honeycomb networks depending on the composition of the
nanomembrane that is in contact with the protein. Scaffolds made of
electroactive TPU:P3TMA nanomembranes are potential candidates for
tissue engineering biomedical applications