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Abstract Most synthetic self-assemblies grow indefinitely into size-unlimited structures, whereas some biological self-assemblies autonomously regulate their size and shape. One mechanism of such self-regulation arises from the chirality of building blocks, inducing their mutual twisting that is incompatible with their long-range ordered packing and thus halts the assembly’s growth at a certain stage. This self-regulation occurs robustly in thermodynamic equilibrium rather than kinetic trapping, and therefore is attractive yet elusive. Until now, studies of self-regulating assemblies have focused on non-responsive systems, whose equilibrium point and corresponding size and shape are hardly changeable. Here, we demonstrate a stimuli-responsive, self-regulating assembly. This assembly consists of chiral and magnetically orientable nanorods, where the effective chirality can be changed by balancing chirality-induced twisting and magnet-induced flattening between nanorods. Consequently, the strength of self-regulation in the assembly is modulable by magnetic field intensity, allowing robust, tunable, and reversible control of its size and shape. Our strategy would provide more biomimetic materials with precision and responsiveness.

Summary: Syntaxin-1A (stx1a) repression causes a neurodevelopmental disorder phenotype, low latent inhibition (LI) behavior, by disrupting 5-hydroxytryptaminergic (5-HTergic) systems. Herein, we discovered that lysine acetyltransferase (KAT) 3B increases stx1a neuronal transcription and TTK21, a KAT3 activator, induces stx1a transcription and 5-HT release in vitro. Furthermore, glucose-derived CSP-TTK21 could restore decreased stx1a expression, 5-HTergic systems in the brain, and low LI in stx1a (+/−) mice by crossing the blood-brain barrier, whereas the KAT3 inhibitor suppresses stx1a expression, 5-HTergic systems, and LI behaviors in wild-type mice. Finally, in wild-type and stx1a (−/−) mice treated with IKK inhibitors and CSP-TTK21, respectively, we show that KAT3 activator-induced LI improvement is a direct consequence of KAT3B-stx1a pathway, not a side effect. In conclusion, KAT3B can positively regulate stx1a transcription in neurons, and increasing neuronal stx1a expression and 5-HTergic systems by a KAT3 activator consequently improves the low LI behavior in the stx1a ablation mouse model.

GTP-triggered release from drug carriers has huge potential in cancer therapy but current carriers suffers from off target release due to ATP also acting as a trigger. Here, the authors report on the development of a microtubule capsule which is engineered to be responsive to only GTP not ATP and demonstrate targeted drug delivery.

The extracellular matrix contributes to tissue regeneration by binding and releasing growth factors. Here the authors present the jigsaw-shaped self-assembling peptide JigSAP as an artificial ECM and show that VEGF-JigSAP has therapeutic effects on the subacute-chronic phase of brain stroke.

The resistive switching of an Ovonic threshold switch (OTS) material is characterized by Poole-Frenkel (PF) conduction and atomic rearrangement originating from chalcogen defects; thus, most OTS materials contain Se and/or Te. In addition to these chalcogen elements, As is included to form rigid amorphous networks. However, since As and Se are toxic, the development of As- and Se-free OTS materials is strongly desired. To realize As-free OTS materials that exhibit a comparable or even superior performance, a new strategy for material development should be established. In this study, we aimed to add Te to a HfO2 insulator to convert the electric conduction mechanism to PF conduction for realizing a selector function. The optical and electrical characteristics of Hf–O–Te ternary amorphous films with various Te contents were investigated. By changing the Te content, the optical bandgap was found to be tuned in the range of 0.46–5 eV, concomitantly with the modification of electrical properties. The electrical characteristics of the films demonstrated a strong compositional dependence, and Hf0.24O0.55Te0.21 was found to exhibit PF conduction, resulting in a selector function with a selectivity of approximately two orders of magnitude. These results indicate that the inclusion of a heavy chalcogen, such as Te, is effective in altering the conduction mechanism of transition-metal oxides and realizing a selector function.

Lateral variations of the surface electric potential and the elastic properties of ultrathin HfxZr1−xO2 films have strong impact on the performance of lead-free ferroelectric devices. Here, we compared lateral uniformity of electric and elastic properties of polycrystalline thin Hf0.55Zr0.45O2 films (10 nm–50 nm) prepared by sputtering on Si. Crystallization of 10-nm-thick films at 600° C and 700 °C resulted in predominantly crystal grains with the orthorhombic and tetragonal phases. Scanning probe microscopy methods including the Kelvin potential microscopy and the force modulation microscopy were employed to investigate the material properties at the nanoscale. Lateral variation of the elastic stiffness and the surface electric potential corresponded to the lateral dimension of grains in pristine films. Point sub-100-nm capacitors formed with a Pt-coated cantilever as a moving electrode showed the ferroelectric behavior. The position-dependent polarization switching and a relative stability of the crystal phases at 1 MV/cm–2 MV/cm were observed in the annealed films. The absence of the monoclinic phase, minimal surface roughness, uniformity of the electric potential, and high elastic modulus made 10-nm Hf0.55Zr0.45O2 films annealed at 600 °C–700 °C in nitrogen as the appealing material for applications in scaled ferroelectric devices.

Ab initio molecular orbital calculations are performed for B13−, Al13−, B12H122−, Al12H122−, Si10, and Si10H16 clusters. The highest occupied molecular orbital (HOMO) of stable and unstable clusters is bonding and antibonding orbitals, respectively. The cluster size dependences of the orbital energies are almost the same for B13− and Al13− icosahedral clusters, when the size and the energy are properly normalized. The normalized factors for size and energy are almost coincident with the ratios of those of the atomic outer s orbitals. On the other hand, the most stable size of B13− is smaller than that of Al13−, and this ratio of the stable size seems to be affected by the ratio of the sizes of the atomic outer p orbitals. As a result, B13− and Al13− icosahedral clusters have antibonding and bonding orbitals for HOMOs and so are unstable and stable, respectively. The situation for B13− and Al13− planar clusters is opposite to that discussed above for the icosahedral clusters. The orbital energies for the metallic bonding Al13− icosahedral and Si10 clusters can be reproduced by the Woods–Saxon model; however, those for the unstable B13− icosahedral and covalent bonding B12H122−, Al12H122−, and Si10H16 clusters cannot be reproduced by the Woods–Saxon model. After optimization of the parameters of the Woods–Saxon model for the Al13− icosahedral and Si10 clusters, the orbital energies are reproduced very well and the sizes and shapes of the potential are reasonable.

A transdermal drug delivery system (TDDS) is a method that provides drug adsorption via the skin. TDDS could replace conventional oral administration and blood administration because it is easily accessible. However, it is still difficult to design efficient TDDS due to the high barrier property of skin covered with stratum corneum, which inhibits the permeation of drug molecules. Thus far, TDDS methods by applying physical stimuli such as microneedles and chemical stimuli such as surfactants have been actively developed. However, it has been hard to avoid inflammation at the administration site because these methods partially destroy the skin tissue. On the other hand, TDDS with nanocarriers minimizing damage to the skin tissues has emerged together with the development of nanotechnology in recent years. This review focuses on current trends in TDDS.