Dynamically Reconfigurable Micro-Patterned Hydrogels Based on Magnetic Pickering Emulsion Droplets.

Reconfigurability within hydrogels has emerged as an attractive functionality that can be used in information encryption, cargo/delivery, environmental remediation, soft robotics, and medicine. Here micro-patterned polymer hydrogels capable of temperature-dependent reconfigurability are fabricated. For this, the hydrogels are provided with micron-sized Pickering emulsion droplets stabilized by magnetic particles, which are capable of harnessing energy from external force fields.

Bottom-Up Preparation of Phase-Separated Polymersomes.

A bottom-up approach to fabricating monodisperse, two-component polymersomes that possess phase-separated ("patchy") chemical topology is presented. This approach is compared with already-existing top-down preparation methods for patchy polymer vesicles, such as film rehydration. These findings demonstrate a bottom-up, solvent-switch self-assembly approach that produces a high yield of nanoparticles of the target size, morphology, and surface topology for drug delivery applications, in this case patchy polymersomes of a diameter of ≈50 nm.

Biocompatible Short-Peptides Fibrin Co-assembled Hydrogels.

Fibrin hydrogels made by self-assembly of fibrinogen obtained from human plasma have shown excellent biocompatible and biodegradable properties and are widely used in regenerative medicine. The fibrinogen self-assembly process can be triggered under physiological conditions by the action of thrombin, allowing the injection of pregel mixtures that have been used as cell carriers, wound-healing systems, and bio-adhesives. However, access to fibrinogen from human plasma is expensive and fibrin gels have limited mechanical properties, which make them unsuitable for certain applications.

One-Pot Synthesis of Oxidation-Sensitive Supramolecular Gels and Vesicles.

Polypeptide-based nanoparticles offer unique advantages from a nanomedicine perspective such as biocompatibility, biodegradability, and stimuli-responsive properties to (patho)physiological conditions. Conventionally, self-assembled polypeptide nanostructures are prepared by first synthesizing their constituent amphiphilic polypeptides followed by postpolymerization self-assembly. Herein, we describe the one-pot synthesis of oxidation-sensitive supramolecular micelles and vesicles.

Combinatorial entropy behaviour leads to range selective binding in ligand-receptor interactions.

From viruses to nanoparticles, constructs functionalized with multiple ligands display peculiar binding properties that only arise from multivalent effects. Using statistical mechanical modelling, we describe here how multivalency can be exploited to achieve what we dub range selectivity, that is, binding only to targets bearing a number of receptors within a specified range. We use our model to characterise the region in parameter space where one can expect range selective targeting to occur, and provide experimental support for this phenomenon.

Modulation of Higher-order Behaviour in Model Protocell Communities by Artificial Phagocytosis.

Collective behaviour in mixed populations of synthetic protocells is an unexplored area of bottom-up synthetic biology. The dynamics of a model protocell community is exploited to modulate the function and higher-order behaviour of mixed populations of bioinorganic protocells in response to a process of artificial phagocytosis. Enzyme-loaded silica colloidosomes are spontaneously engulfed by magnetic Pickering emulsion (MPE) droplets containing complementary enzyme substrates to initiate a range of processes within the host/guest protocells.

Molecular bionics - engineering biomaterials at the molecular level using biological principles.

Life and biological units are the result of the supramolecular arrangement of many different types of molecules, all of them combined with exquisite precision to achieve specific functions. Taking inspiration from the design principles of nature allows engineering more efficient and compatible biomaterials. Indeed, bionic (from bion-, unit of life and -ic, like) materials have gained increasing attention in the last decades due to their ability to mimic some of the characteristics of nature systems, such as dynamism, selectivity, or signalling.

Effect of functionalized PHEMA micro- and nano-particles on the viscoelastic properties of fibrin-agarose biomaterials.

Two types of PHEMA-based particles, exhibiting either carboxyl or tertiary ammine functional groups, were incorporated to fibrin-agarose (FA) hydrogels, and the effect of the addition of these synthetic particles on the viscoelastic and microstructural properties of the biomaterials was evaluated. Experimental results indicated that the incorporation of both types of polymeric particles to FA scaffolds was able to improve the biomechanical properties of the biomaterials under steady state and oscillatory shear stresses, resulting in scaffolds characterized by higher values of the storage, loss, and shear moduli. In addition, the microstructural evaluation of the scaffolds showed that the nanoparticles exhibiting carboxyl functional groups were homogeneously distributed across the fibrous network of the hydrogels.

Phagocytosis-inspired behaviour in synthetic protocell communities of compartmentalized colloidal objects.

The spontaneous assembly of micro-compartmentalized colloidal objects capable of controlled interactions offers a step towards rudimentary forms of collective behaviour in communities of artificial cell-like entities (synthetic protocells). Here we report a primitive form of artificial phagocytosis in a binary community of synthetic protocells in which multiple silica colloidosomes are selectively ingested by self-propelled magnetic Pickering emulsion (MPE) droplets comprising particle-free fatty acid-stabilized apertures. Engulfment of the colloidosomes enables selective delivery and release of water-soluble payloads, and can be coupled to enzyme activity within the MPE droplets.

Biocompatible magnetic core-shell nanocomposites for engineered magnetic tissues.

The inclusion of magnetic nanoparticles into biopolymer matrixes enables the preparation of magnetic field-responsive engineered tissues. Here we describe a synthetic route to prepare biocompatible core-shell nanostructures consisting of a polymeric core and a magnetic shell, which are used for this purpose. We show that using a core-shell architecture is doubly advantageous.

Optimizing the magnetic response of suspensions by tailoring the spatial distribution of the particle magnetic material.

We report an experimental enhancement of the magnetic susceptibility of suspensions of particles that is related to the spatial distribution of the magnetic phase in the particles. At low field, the susceptibility of suspensions of nickel-coated diamagnetic spheres was approximately 75% higher than that of suspensions of solid nickel spheres with the same nickel content. This result was corroborated by magnetostatics theory and simulation.

Colloids on the frontier of ferrofluids. Rheological properties.

This paper is devoted to the steady-state rheological properties of two new kinds of ferrofluids. One of these was constituted by CoNi nanospheres of 24 nm in diameter, whereas the other by CoNi nanofibers of 56 nm in length and 6.6 nm in width.

Stability and magnetorheological behaviour of magnetic fluids based on ionic liquids.

This paper reports the preparation of magnetic fluids consisting of magnetite nanoparticles dispersed in an ionic liquid. Different additives were used in order to stabilize the fluids. Colloidal stability was checked by magnetic sedimentation, centrifugation and direct observation.

Steric repulsion as a way to achieve the required stability for the preparation of ionic liquid-based ferrofluids.

With this work we would like to emphasize the necessity of steric repulsion to stabilize novel ionic liquid-based ferrofluids. For this purpose, we prepared a suspension of magnetite nanoparticles coated with a double layer of oleic acid, dispersed in 1-ethyl-3-methylimidazolium ethylsulphate ([EMIM][EtSO(4)]). For comparison, a suspension of bare magnetite nanoparticles in [EMIM][EtSO(4)] was also prepared.