Effect of Imposing Spatial Constraints on Low Molecular Weight Gels.

We outline the effect of imposing spatial constraints during gelation on hydrogels formed by dipeptide-based low molecular weight gelators. The gels were formed via either a solvent switch or a change in pH and formed in different sized vessels to produce gels of different thickness while maintaining the same volume. The different methods of gelation led to gels with different underlying microstructure.

Investigating Aggregation Using In Situ Electrochemistry and Small-Angle Neutron Scattering.

Using small-angle neutron scattering to investigate the aggregation of self-assembling molecules is well established. Some of these molecules are electrochemically useful, for example, in electrochromic devices. Electrochemistry can also be used in some cases to induce aggregation.

Mechanical Characterization of Multilayered Hydrogels: A Rheological Study for 3D-Printed Systems.

We describe rheological protocols to study layered and three-dimensional (3D)-printed gels. Our methods allow us to measure the properties at different depths and determine the contribution of each layer to the resulting combined properties of the gels. We show that there are differences when using different measuring systems for rheological measurement, which directly affects the resulting properties being measured.

Tuning the antimicrobial activity of low molecular weight hydrogels using dopamine autoxidation.

We present a method to trigger the formation of dipeptide-based hydrogels by the simple addition of dopamine. Dopamine undergoes oxidation in air, reducing the pH to induce gelation. The production of polydopamine and release of reactive oxygen species such as hydrogen peroxide confers antimicrobial activity.

Isotopic Control over Self-Assembly in Supramolecular Gels.

It is common to switch between HO and DO when examining peptide-based systems, with the assumption being that there are no effects from this change. Here, we describe the effect of changing from HO to DO in a number of low-molecular-weight dipeptide-based gels. Gels are formed by decreasing the pH.

Annealing Supramolecular Gels by a Reaction Relay.

Supramolecular gels have potential in many areas. In many cases, a major drawback is that the gels are formed at a high rate. As a result, nonoptimal, kinetically trapped self-assembled structures are often formed, leading to gels that can be hard to reproduce and control.

PAINT-ing Fluorenylmethoxycarbonyl (Fmoc)-Diphenylalanine Hydrogels.

Self-assembly of fluorenylmethoxycarbonyl-protected diphenylalanine (FmocFF) in water is widely known to produce hydrogels. Typically, confocal microscopy is used to visualize such hydrogels under wet conditions, that is, without freezing or drying. However, key aspects of hydrogels like fiber diameter, network morphology and mesh size are sub-diffraction limited features and cannot be visualized effectively using this approach.

Controlling the properties of the micellar and gel phase by varying the counterion in functionalised-dipeptide systems.

The micellar aggregates formed at high pH for dipeptide-based gelators can be varied by using different alkali metal salts to prepare the solutions. The nature of the micellar aggregates directly affects the properties of the resulting gels.

On the Mechanical Properties of -Functionalised Dipeptide Gels.

The properties of a hydrogel are controlled by the underlying network that immobilizes the solvent. For gels formed by the self-assembly of a small molecule, it is common to show the primary fibres that entangle to form the network by microscopy, but it is difficult to access information about the network. One approach to understand the network is to examine the effect of the concentration on the rheological properties, such that G'∝ c, where G' is the storage modulus and c is the concentration.

Using cavitation rheology to understand dipeptide-based low molecular weight gels.

The study of dipeptide-based hydrogels has been the focus of significant effort recently due to their potential for use in a variety of biomedical and biotechnological applications. It is essential to study the mechanical properties in order to fully characterise and understand this type of soft materials. In terms of mechanical properties, the linear elastic modulus is normally measured using traditional shear rheometry.

Annealing multicomponent supramolecular gels.

Annealing is widely used as a means of changing the physical properties of a material. The rate of heating and cooling used in the annealing process controls the final properties. Annealing can be used as a means of driving towards the, or at least a, thermodynamic minimum.

SPIONs for cell labelling and tracking using MRI: magnetite or maghemite?

Although there is extensive literature covering the biomedical applications of superparamagnetic iron oxide nanoparticles (SPIONs), the phase of the iron oxide core used is not often taken into account when cell labelling and tracking studies for regenerative medicine are considered. Here, we use a co-precipitation reaction to synthesise particles of both magnetite- (FeO) and maghemite- (γ-FeO) based cores and consider whether the extra synthesis step to make maghemite based particles is advantageous for cell tracking.

Optimising low molecular weight hydrogels for automated 3D printing.

Hydrogels prepared from low molecular weight gelators (LMWGs) are formed as a result of hierarchical intermolecular interactions between gelators to form fibres, and then further interactions between the self-assembled fibres via physical entanglements, as well as potential branching points. These interactions can allow hydrogels to recover quickly after a high shear rate has been applied. There are currently limited design rules describing which types of morphology or rheological properties are required for a LMWG hydrogel to be used as an effective, printable gel.