A highly oriented cubic phase formed by lipids under shear

We demonstrate the formation of a macroscopically oriented inverse bicontinuous cubic (QII) lipid phase from a sponge (L3) phase by controlled hydration during shear flow. The L3 phase was the monoolein/ butanediol/water system; the addition of water reduces the butanediol concentration, inducing the formation of a diamond (QIID) cubic phase, which is oriented by the shear flow. The phenomenon was reproduced in both capillary and Couette geometries, indicating that this represents a robust general route for the production of highly aligned bulkQII samples, with applications in nanomaterial templating and protein research

Controlling And Understanding Single And Multicomponent Supramolecular Gels

Supramolecular gels can be prepared by the self-assembly of small molecules into fibrous structures. The properties of the resulting gels depend on how the gels are formed, such that gels with very different properties can be prepared from a single gelator if different gelation methods are used. We have been working to understand this, and for example can prepare gels that can or cannot be 3D-printed from the same gelator by varying gelation method. Here, we will focus on explaining the design rules. As specific examples, we will discuss how varying the chirality of our dipeptide-based gelators can be used to control the self-assembled aggregates, leading to differences in the final gels. We will also show how our understanding can be expanded to multicomponent systems, where each component gelator can form gels alone. In these mixed systems, we can control assembly such that self-sorted multicomponent gels are formed. We will show how such systems can be characterised to prove this assembly and how this approach can be used to prepare gels with controlled and specific properties

Simple Host-Guest Chemistry To Modulate the Process of Concentration and Crystallization of Membrane Proteins by Detergent Capture in a Microfluidic Device

This paper utilizes cyclodextrin-based host-guest chemistry in a microfluidic device to modulate the crystallization of membrane proteins and the process of concentration of membrane protein samples. Methyl-beta-cyclodextrin (MBCD) can efficiently capture a wide variety of detergents commonly used for the stabilization of membrane proteins by sequestering detergent monomers. Reaction Center (RC) from Blastochloris viridis was used here as a model system. In the process of concentrating membrane protein samples, MBCD was shown to break up free detergent micelles and prevent them from being concentrated. The addition of an optimal amount of MBCD to the RC sample captured loosely bound detergent from the protein-detergent complex and improved sample homogeneity, as characterized by dynamic light scattering. Using plug-based microfluidics, RC crystals were grown in the presence of MBCD, giving a different morphology and space group than crystals grown without MBCD. The crystal structure of RC crystallized in the presence of MBCD was consistent with the changes in packing and crystal contacts hypothesized for removal of loosely bound detergent. The incorporation of MBCD into a plug-based microfluidic crystallization method allows efficient use of limited membrane protein sample by reducing the amount of protein required and combining sparse matrix screening and optimization in one experiment. The use of MBCD for detergent capture can be expanded to develop cyclodextrin-derived molecules for fine-tuned detergent capture and thus modulate membrane protein crystallization in an even more controllable way

Control of nanomaterial self-assembly in ultrasonically levitated droplets

We demonstrate that acoustic trapping can be used to levitate and manipulate droplets of soft matter, in particular, lyotropic mesophases formed from selfassembly of different surfactants and lipids, which can be analyzed in a contact-less manner by X-ray scattering in a controlled gas-phase environment. On the macroscopic length scale, the dimensions and the orientation of the particle are shaped by the ultrasonic field, while on the microscopic length scale the nanostructure can be controlled by varying the humidity of the atmosphere around the droplet. We demonstrate levitation and in situ phase transitions of micellar, hexagonal, bicontinuous cubic, and lamellar phases. The technique opens up a wide range of new experimental approaches of fundamental importance for environmental, biological, and chemical research

Investigating the self-assembly of 2NapFF and ureido-pyrimidinone multicomponent systems for cell culture

Low molecular weight gels are formed via the self-assembly of small molecules into fibrous structures. In the case of hydrogels, these networks entrap large volumes of water, yielding soft materials. Such gels tend to have weak mechanical properties and a high permeability for cells, making them particularly appealing for regenerative medicine applications. Ureido-pyrimidinone (UPy) supramolecular gelators are self-assembling systems that have demonstrated excellent capabilities as biomaterials. Here, we combine UPy-gelators with another low molecular weight gelator, the functionalized dipeptide 2NapFF. We have successfully characterized these multicomponent systems on a molecular and bulk scale. The addition of 2NapFF to a crosslinked UPy hydrogel significantly increased hydrogel stiffness from 30 Pa to 1300 Pa. Small-angle X-ray scattering was used to probe the underlying structures of the systems and showed that the mixed UPy and 2NapFF systems resemble the scattering data produced by the pristine UPy systems. However, when a bifunctional UPy-crosslinker was added, the scattering was close to that of the 2NapFF only samples. The results suggest that the crosslinker significantly influences the assembly of the low molecular weight gelators. Finally, we analysed the biocompatibility of the systems using fibroblast cells and found that the cells tended to spread more effectively when the crosslinking species was incorporated. Our results emphasise the need for thorough characterisation at multiple length scales to finely control material properties, which is particularly important for developing novel biomaterials.</p

Isotopic control over self-assembly in supramolecular gels

It is common to switch between H2O and D2O 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 H2O to D2O in a number of low molecular weight dipeptide-based gels. Gels are formed by decreasing the pH. In most cases, there is little dif-ference in the structures formed at high pH, but this is not universally true. On lowering the pH, the ki-netics of gelation are affected and, in some cases, the structures underpinning the gel network are dif-ferent. Where there are differences in the self-assembled structures, the resulting gel properties are different. We therefore show isotopic control over gel properties is possible