Ella Gale

On the subtle tuneability of cellulose hydrogels: implications for binding of biomolecules demonstrated for CBM 1

Cellulose-based hydrogel materials prepared by regeneration from cellulose solutions in ionic liquids, or ionic liquid containing solvent mixtures (organic electrolyte solutions), are becoming widely used in a range of applications from tissue scaffolds to membrane ionic diodes. In all such applications knowledge of the nature of the hydrogel with regards to porosity (pore size and tortuosity) and material structure and surface properties (crystallinity and hydrophobicity) is critical. Here we report significant changes in hydrogel properties, based on the choice of cellulose raw material (α- or bacterial cellulose - with differing degree of polymerization) and regeneration solvent (methanol or water). Focus is on bioaffinity applications, but the findings have wide ramifications, including in biomedical applications and cellulose saccharification. Specifically, we report that the choice of cellulose and regeneration solvent influences the surface area accessible to a family 1 carbohydrate-binding module (CBM), CBM affinity for the cellulose material, and rate of migration through the hydrogel. By regenerating bacterial cellulose in water, a maximum accessible surface area of 33 m2 g-1 was achieved. However, the highest CBM migration rate, 1.76 μm2 min-1, was attained by regenerating α-cellulose in methanol, which also resulted in the maximum affinity of the biomolecule for the material. Thus, it is clear that if regenerated cellulose hydrogels are to be used as support materials in bioaffinity (or other) applications, a balance between accessible surface area and affinity, or migration rate, must be achieved.

On coupled oscillator dynamics and incident behaviour patterns in slime mould Physarum polycephalum: emergence of wave packets, global streaming clock frequencies and anticipation of periodic stimuli

Slime mould Physarum polycephalum is a single cell which physically oscillates via contraction of actomyosin in order to achieve motility. Several of its apparently ‘intelligent’ behaviour patterns such as anticipatory responses to periodic stimuli have recently been attributed as functions of the coupling between the oscillating intracellular reactions which drive its rhythmic muscular contraction, but the mechanisms that underlie these phenomena have not yet been experimentally verified. Through laboratory investigations in which we entrain the P. polycephalum plasmodium via periodic ultraviolet light exposure we find that this phenomenon is likely to result from biasing its various oscillating life processes through altering local concentration profiles of various allosteric molecules and their effectors. This temporarily overwrites the global streaming clock frequency and eradicates the wave packets usually observed in slime mould biomechanical oscillation. This response is likened to an intracellular chemical memory. We proceed to present a multi-agent model in which we demonstrate that travelling waves and oscillatory clock frequencies may emerge in the virtual organism’s biomechanical oscillator, although anticipatory responses cannot be replicated by simple mechanical interactions. We conclude by arguing that these phenomena are best characterised as analogue computation and discuss practical applications therein. Graphical Abstract The Physarum polycephalum actin network in a plasmodial tubule. SiR-actin staining, scale bar 200 μm.

Memristors in Unconventional Computing: How a Biomimetic Circuit Element Can be Used to Do Bioinspired Computation

Memristors differ from resistors by possessing a memory, and both synapses and neurons have been discussed as biological memristors. The short-term memory of the memristor (or spiking profile) is similar in form to neural spikes. Thus, memristors are obvious candidates for building biomimetic circuits and computers. In this chapter, we review some recent experimental results in the area of memritor-based spike computing. We demonstrate how memristor spikes are a real-world memristor model of an inhibitory neuron, then we demonstrate the complex emergent behaviour from networks of memristors which resembles neural dynamics, we then expose these memristor networks to living neural cells, where the memristor state is altered by cellular action. Further investigation of the memristor spiking process allows us to elucidate design rules for spiking logic gates, and we demonstrate a novel full adder instantiated in a single memristor. Spiking memristor computation might be the best route to truly neuromorphic computers.

Regenerated Cellulose Hydrogels as Bioaffinity Attachment Supports for Carbohydrate-Binding Module 1

Modification of cellulose hydrogels by choice of cellulose and regeneration solvent influences the surface area accessible to a family 1 carbohydrate-binding module, its affinity to the cellulose material and rate of migration through the hydrogel. The hydrogels may be used as support materials in bioaffinity applications but a compromise between accessible surface area and affinity, or migration rate, must be made.