Physical Gelation of Polypeptide–Polyelectrolyte–Polypeptide (ABA) Copolymer in Solution

Chiral gold nanoparticles enantioselectively rescue memory deficits in a mouse model of Alzheimer's disease

Preventing aggregation of amyloid beta (Aβ) peptides is a promising strategy for the treatment of Alzheimer’s disease (AD), and gold nanoparticles have previously been explored as a potential anti-Aβ therapeutics. Here we design and prepare 3.3 nm L- and D-glutathione stabilized gold nanoparticles (denoted as L3.3 and D3.3, respectively). Both chiral nanoparticles are able to inhibit aggregation of Aβ42 and cross the blood-brain barrier (BBB) following intravenous administration without noticeable toxicity. D3.3 possesses a larger binding affinity to Aβ42 and higher brain biodistribution compared with its enantiomer L3.3, giving rise to stronger inhibition of Aβ42 fibrillation and better rescue of behavioral impairments in AD model mice. This conjugation of a small nanoparticle with chiral recognition moiety provides a potential therapeutic approach for AD.

Nanoparticles are being explored as a potential method to target Aβ aggregation in Alzheimer’s disease. Here, the authors develop gold nanoparticles that were capped with chiral L or D-glutathione which has been shown to improve BBB permeability and demonstrate their ability to improve cognitive function in a mouse model of AD.

Aggregation of amyloid peptides into fibrils driven by nanoparticles and their curvature effect

Fibrillation of amyloid peptides induces human diseases such as Alzheimer's disease, which has become a huge challenge. Some nanoparticles (NPs) could enhance peptide fibrillation by decreasing the lag time, yet how the size and shape of NPs affect amyloid fibrillation as well as the underlying mechanism remains unclear. Here, we investigated amyloid fibrillation on the surface of spherical NPs and cylindrical nanorods (NRs) of different sizes using coarse-grained Monte Carlo simulations. We focused on the curvature effect of NPs/NRs on the adsorption and fibrillation of peptide chains due to the size/shape difference. As the size of the NPs/NRs increases, the number of assembled peptide chains shows a non-monotonic tendency, and there is an optimal size for the highest adsorption. In most cases, the NRs could adsorb more peptides than the NPs of the same diameter due to the lower curvature. The mechanism beneath these observations was elucidated from a thermodynamic point of view. Our findings could provide a physical basis for the adsorption and fibrillation of amyloid peptides on NPs, and guide the design of future curvature-dependent NP-based amyloid treatment.

Stearoyl-appended pendant amino acid-based hyperbranched polymers for selective gelation of oil from oil/water mixtures

Stearic acid-appended pendant amino acid-based poly(methacrylate) hyperbranched polymers were developed for the phase-selective organogelation of crude oil from a binary mixture of oil/water.

Spatial Rearrangement and Mobility Heterogeneity of an Anionic Lipid Monolayer Induced by the Anchoring of Cationic Semiflexible Polymer Chains

We use Monte Carlo simulations to investigate the interactions between cationic semiflexible polymer chains and a model fluid lipid monolayer composed of charge-neutral phosphatidyl-choline (PC), tetravalent anionic phosphatidylinositol 4,5-bisphosphate (PIP₂), and univalent anionic phosphatidylserine (PS) lipids. In particular, we explore how chain rigidity and polymer concentration influence the spatial rearrangement and mobility heterogeneity of the monolayer under the conditions where the cationic polymers anchor on the monolayer. We find that the anchored cationic polymers only sequester the tetravalent PIP₂ lipids at low polymer concentrations, where the interaction strength between the polymers and the monolayer exhibits a non-monotonic dependence on the degree of chain rigidity. Specifically, maximal anchoring occurs at low polymer concentrations, when the polymer chains have an intermediate degree of rigidity, for which the PIP₂ clustering becomes most enhanced and the mobility of the polymer/PIP₂ complexes becomes most reduced. On the other hand, at sufficiently high polymer concentrations, the anchoring strength decreases monotonically as the chains stiffen-a result that arises from the pronounced competitions among polymer chains. In this case, the flexible polymers can confine all PIP₂ lipids and further sequester the univalent PS lipids, whereas the stiffer polymers tend to partially dissociate from the monolayer and only sequester smaller PIP₂ clusters with greater mobilities. We further illustrate that the mobility gradient of the single PIP₂ lipids in the sequestered clusters is sensitively modulated by the cooperative effects between anchored segments of the polymers with different rigidities. Our work thus demonstrates that the rigidity and concentration of anchored polymers are both important parameters for tuning the regulation of anionic lipids.