Chemokinetic Scattering, Trapping, and Avoidance of Active Brownian Particles.

We present a theory of chemokinetic search agents that regulate directional fluctuations according to distance from a target. A dynamic scattering effect reduces the probability to penetrate regions with high fluctuations and thus reduces search success for agents that respond instantaneously to positional cues. In contrast, agents with internal states that initially suppress chemokinesis can exploit scattering to increase their probability to find the target. Using matched asymptotics between the case of diffusive and ballistic search, we obtain analytic results beyond Fox colored noise approximation.

Influence of the reducing-end anomeric configuration of the Man9 epitope on DC-SIGN recognition.

High-mannose (Man9GlcNAc2) is the main carbohydrate unit present in viral envelope glycoproteins such as gp120 of HIV and the GP1 of Ebola virus. This oligosaccharide comprises the Man9 epitope conjugated to two terminal N-acetylglucosamines by otherwise rarely-encountered ß-mannose glycosidic bond. Formation of this challenging linkage is the bottleneck of the few synthetic approaches described to prepare high mannose. Herein, we report the synthesis of the Man9 epitope with both alpha and beta configurations at the reducing end, and subsequent evaluation of the impact of this configuration on binding to natural receptor of high-mannose, DC-SIGN. Using fluorescence polarization assays, we demonstrate that both anomers bind to DC-SIGN with comparable affinity. These relevant results therefore indicate that the more synthetically-accesible Man9 alpha epitope may be deployed as ligand for DC-SIGN in both in vitro and in vivo biological assays.

Synthesis of Highly Efficient Multivalent Disaccharide/[60]Fullerene Nanoballs for Emergent Viruses.

After the last epidemic of the Zika virus (ZIKV) in Brazil that peaked in 2016, growing evidence has been demonstrated of the link between this teratogenic flavivirus and microcephaly cases. However, no vaccine or antiviral drug has been approved yet. ZIKV and Dengue viruses (DENV) entry to the host cell takes place through several receptors, including dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN), so that the blockade of this receptor through multivalent glycoconjugates supposes a promising biological target to inhibit the infection process. In order to get enhanced multivalency in biocompatible systems, tridecafullerenes appended with up to 360 1,2-mannobiosides have been synthesized using a strain-promoted cycloaddition of azides to alkynes (SPAAC) strategy. These systems have been tested against ZIKV and DENV infection, showing an outstanding activity in the picomolar range.

Straightforward synthesis of Man9, the relevant epitope of the high-mannose oligosaccharide.

The high-mannose oligosaccharide (or its corresponding Man9 epitope) is the most abundant structure present in pathogen envelope glycoproteins. These glycans play a key role in the pathogenesis of several pathogens and also in the communication with the immune system. Understanding the mechanism of action of these glycans requires the access to pure and chemically well-defined structures in reasonable amounts. The synthesis of these complex branched oligosaccharides is not trivial and few syntheses are reported in the literature with several synthetic and purification steps and low overall yields. In this work, we described a very efficient synthetic alternative to access this relevant Man9 epitope in a very straightforward manner.

Host-derived mannose glycans trigger a pathogenic γδ T cell/IL-17a axis in autoimmunity.

Autoimmune diseases are life-threatening disorders that cause increasing disability over time. Systemic lupus erythematosus (SLE) and other autoimmune diseases arise when immune stimuli override mechanisms of self-tolerance. Accumulating evidence has demonstrated that protein glycosylation is substantially altered in autoimmune disease development, but the mechanisms by which glycans trigger these autoreactive immune responses are still largely unclear. In this study, we found that presence of microbial-associated mannose structures at the surface of the kidney triggers the recognition of DC-SIGN-expressing γδ T cells, inducing a pathogenic interleukin-17a (IL-17a)-mediated autoimmune response. Mice lacking Mgat5, which have a higher abundance of mannose structures in the kidney, displayed increased γδ T cell infiltration into the kidney that was associated with spontaneous development of lupus in older mice. N-acetylglucosamine supplementation, which promoted biosynthesis of tolerogenic branched N-glycans in the kidney, was found to inhibit γδ T cell infiltration and control disease development. Together, this work reveals a mannose-γδ T cell-IL-17a axis in SLE immunopathogenesis and highlights glycometabolic reprogramming as a therapeutic strategy for autoimmune disease treatment.

Measuring the refractive index and sub-nanometre surface functionalisation of nanoparticles in suspension.

Direct measurements to determine the degree of surface coverage of nanoparticles by functional moieties are rare, with current strategies requiring a high level of expertise and expensive equipment. Here, a practical method to determine the ratio of the volume of the functionalisation layer to the particle volume based on measuring the refractive index of nanoparticles in suspension is proposed. As a proof of concept, this technique is applied to poly(methyl methacrylate) (PMMA) nanoparticles and semicrystalline carbon dots functionalised with different surface moieties, yielding refractive indices that are commensurate to those from previous literature and Mie theory. In doing so, it is demonstrated that this technique is able to optically detect differences in surface functionalisation or composition of nanometre-sized particles. This non-destructive and rapid method is well-suited for in situ industrial particle characterisation and biological applications.

Bottom-Up Synthesis of Supported Thioureas and Their Use in Enantioselective Solvent-Free Aza-Henry and Michael Additions.

Two sets of supported chiral thioureas, which differ in the length of the tether that connects the chiral appendage to the polymer structure and the effective functionalization, have been prepared by copolymerization of styrene, novel styryl thioureas derived from l-valine, and divinylbenzene. The efficiency of these polymeric thioureas has been tested in two different enantioselective transformations, namely, aza-Henry and nitro-Michael reactions, in neat reaction conditions. The obtained results show that it is possible to recycle the thiourea, and they are able to promote the reactions with good enantioselectivity at a low catalyst loading.