Organic–Inorganic Hierarchical Self‐Assembly into Robust Luminescent Supramolecular Hydrogel

Luminescent hydrogels are of great potential for many fields, particularly serving as biomaterials ranging from fluorescent sensors to bioimaging agents. Here, robust luminescent hydrogels are reported using lanthanide complexes as emitting sources via a hierarchical organic–inorganic self‐assembling strategy. A new organic ligand is synthesized, consisting of a terpyridine unit and two flexibly linked methylimidazole moieties to coordinate with europium(III) (Eu³⁺) tri‐thenoyltrifluoroacetone (Eu(TTA)₃), leading to a stable amphiphilic Eu³⁺‐containing monomer. Synergistic coordination of TTA and terpyridine units allows the monomer to self‐assemble into spherical micelles in water, thus maintaining the luminescence of Ln complexes in water. The micelles further coassemble with exfoliated Laponite nanosheets coated with sodium polyacrylate into networks based on the electrostatic interactions, resulting in the supramolecular hydrogel possessing strong luminescence, extraordinary mechanical property, as well as self‐healing ability. The results demonstrate that hierarchical organic–inorganic self‐assembly is a versatile and effective strategy to create luminescent hydrogels containing lanthanide complexes, giving rise to great potential applications as a soft material.     

Temperature‐Switchable Assembly of Supramolecular Virus–Polymer Complexes

Here a method is presented for the temperature‐switchable assembly of viral particles into large hierarchical complexes. Dual‐functional diblock copolymers consisting of poly(diethyleneglycol methyl ether methacry­late) (poly(DEGMA)) and poly((2‐dimethylamino)ethyl methacrylate) (poly(DMAEMA)) blocks self‐assemble electrostatically with cowpea chlorotic mottle virus (CCMV) particles into micrometer‐sized objects as a function of temperature. The poly(DMAEMA) block carries a positive charge, which can interact electrostatically with the negatively charged outer surface of the CCMV capsid. When the solution temperature is increased above 40 °C, to cross the cloud point temperature (T_cp) of the DEGMA block, the polymer chains collapse on the surface of the virus particle, which makes them partially hydrophobic, and consequently causes the formation of large hierarchical assemblies. Disassembly of the virus–polymer complexes can be induced by reducing the solution temperature below the T_cp, which allows the poly(DEGMA) blocks to rehydrate and free virus particles to be released. The assembly process is fully reversible and can sustain several heating–cooling cycles. Importantly, this method relies on reversible supramolecular interactions and therefore avoids the irreversible covalent modification of the particle surface. This study illustrates the potential of temperature‐responsive polymers for controlled binding and releasing of virus particles.     

Hierarchical Self‐Assembly of a Dandelion‐Like Supramolecular Polymer into Nanotubes for use as Highly Efficient Aqueous Light‐Harvesting Systems

A dandelion‐like supramolecular polymer (DSP) with a “sphere‐star‐parachute” topological structure consisting of a spherical hyperbranched core and many parachute‐like arms is constructed by the non‐covalent host–guest coupling between a cyclodextrin‐endcapped hyperbranched multi‐arm copolymer (host) and many functionalized adamantanes with each having three alkyl chain arms (guests). The obtained DSPs can further self‐assemble into nanotubes in water in a hierarchical way from vesicles to nanotubes through sequential vesicle aggregation and fusion steps. The nanotubes have a bilayer structure consisting of multiple “hydrophobic‐hyperbranched‐hydrophilic” layers. Such a structure is very useful for constructing a chlorosome‐like artificial aqueous light‐harvesting system, as demonstrated here, via the incorporation of hydrophobic 4‐(2‐hydroxyethylamino)‐7‐nitro‐2,1,3‐benzoxadiazole as donors inside the hyperbranched cores of the nanotubes and the hydrophilic Rhodamine B as the acceptors immobilized on the nanotube surfaces. This as‐prepared nanotube light harvesting system demonstrates unexpectedly high energy transfer efficiency (above 90%) in water. This extends supramolecular polymers with more complex topological structure, special self‐assembly behavior, and new functionality.     

Electrostatically Directed Self‐Assembly of Ultrathin Supramolecular Polymer Microcapsules

Supramolecular self‐assembly offers routes to challenging architectures on the molecular and macroscopic scale. Coupled with microfluidics it has been used to make microcapsules—where a 2D sheet is shaped in 3D, encapsulating the volume within. In this paper, a versatile methodology to direct the accumulation of capsule‐forming components to the droplet interface using electrostatic interactions is described. In this approach, charged copolymers are selectively partitioned to the microdroplet interface by a complementary charged surfactant for subsequent supramolecular cross‐linking via cucurbit[8]uril. This dynamic assembly process is employed to selectively form both hollow, ultrathin microcapsules and solid microparticles from a single solution. The ability to dictate the distribution of a mixture of charged copolymers within the microdroplet, as demonstrated by the single‐step fabrication of distinct core–shell microcapsules, gives access to a new generation of innovative self‐assembled constructs.     

Nano‐Self‐Assembly of Nucleic Acids Capable of Transfection without a Gene Carrier

Nonviral gene carriers based on electrostatic interaction, encapsulation, or absorption require a large amount of polymer carrier to achieve reasonable transfection efficiencies. With cationic nanoparticles, for example, genes interact only with the surface of the nanoparticles, resulting in a low surface area to volume ratio (SA/V = 3/r). A large volume of carrier, therefore, is required to deliver a small copy number of genes. In this study, it is demonstrated that a nano‐self‐assembly of nucleic acids transfects itself into cells spontaneously, without the need for a gene carrier. The cellular uptake of this nanoassembly occurs through a number of endocytosis mechanisms. Once within the cell, the nanoassembly can escape endolysosomal vesicles and facilitate gene transfection. This nano‐self‐assembly consisting of zinc and plasmid DNA or siRNA, termed the Zn/DNA or Zn/siRNA nanocluster, is formed through the binding of Zn²⁺ ions to the phosphate groups of nucleic acids. The method described in this paper represents a new platform for carrier‐free gene delivery that can be used to deliver any plasmid DNA or siRNA without the requirement for a specific modification in the nucleic acids or complicated steps to prepare dense particles.     

Protection Switching Methods for Point‐to‐Multipoint Connections in Packet Transport Networks

In this paper, we discuss the issues of providing protection for point‐to‐multipoint connections in both Ethernet and MPLS‐TP‐based packet transport networks. We introduce two types of per‐leaf protection–linear and ring. Neither of the two types requires that modifications to existing standards be made. Their performances can be improved by a collective signal fail mechanism proposed in this paper. In addition, two schemes — tree protection and hybrid protection — are newly proposed to reduce the service recovery time when a single failure leads to multiple signal fail events, which in turn places a significant amount of processing burden upon a root node. The behavior of the tree protection protocol is designed with minimal modifications to existing standards. The hybrid protection scheme is devised to maximize the benefits of per‐leaf protection and tree protection. To observe how well each scheme achieves an efficient traffic recovery, we evaluate their performances using a test bed as well as computer simulation based on the formulae found in this paper.     

Supramolecular Self‐Assembly of Nanoconfined Ionic Liquids for Fast Anisotropic Ion Transport

Materials involving nanoconfinement of ionic liquids (ILs) have been pursued for functionalities and ionic devices. However, their complex synthesis, challenges to achieve long‐range order, and laborious tunability limit their practical implementation. Herein, these challenges are addressed by complexing surfactants to ILs, yielding a facile, modular, and scalable approach. Based on structural screening, ionic complexation of di‐n‐nonylamine to the terminal sulfonic acid of 1‐(4‐sulfobutyl)‐3‐methylimidazolium hydrogen sulfate IL is selected as a proof of concept. Spontaneous homeotropic smectic order over micrometers is observed, with alternating ionic and alkyl layers. The 1 nm thick ionic layers involve 2D crystalline internal order up to 150 °C, strongly promoting anisotropic ion transport (σ_||/σ_⊥ > 6500), and curiously, still allowing fluidity. High ionic conductivity of 35 mS cm^?1 and mesoscopic diffusion coefficient of ≈10^?5 cm² s^?1 at 150 °C along the ionic layers are observed. Fast anisotropic ion transport by simply complexing two components open doors to functional materials and applications.     

Analysis of Single‐RF MIMO Receiver with Beam‐Switching Antenna

This paper proposes a single‐RF MIMO receiver that adopts a beam‐switching antenna (BSA) instead of a conventional array antenna. The beauty of the proposed single‐RF MIMO receiver with BSA is that it can be deployed in a very small physical space while achieving a full spatial multiplexing gain. Our analysis has revealed that the use of a BSA inevitably results in the spectrum spreading effect at the RF output, which in turn causes an SNR decrease and adjacent channel interference (ACI). Two novel receiver techniques are proposed to mitigate the issues of redundant sub‐band suppression and ACI avoidance. Numerical analysis results verify the performance improvement from the proposed receiver techniques.     

Fibrillar Constructs from Multilevel Hierarchical Self‐Assembly of Discotic and Calamitic Supramolecular Motifs

We here report on polymeric solid‐state self‐assembly leading to organization over six length scales, ranging from the molecular scale up to the macroscopic length scale. We combine several concepts, i.e., rod‐like helical and disc‐like liquid crystallinity, block copolymer self‐assembly, DNA‐like interactions to form an ionic polypeptide–nucleotide complex and packing frustration to construct mesoscale fibrils. Ionic complexation of anionic deoxyguanosine monophosphate (dGMP) and triblock coil–rod–coil copolypeptides is used with cationic end blocks and a helical rod‐like midblock. The guanines undergo Hoogsteen pairing to form supramolecular discs, they π‐stack into columns that self‐assemble into hexagonal arrays that are controlled by the end blocks. Packing frustration between the helical rods from the block copolymer midblock and the discotic motif limits the lateral growth of the assembly thus affording mesoscale fibrils, which in turn, form an open fibrillar network. The concepts suggest new rational methodologies to construct structures on multiple length scales in order to tune polymer properties.     

From Nanofibers to Nanorods: Nanostructure of Peptide‐Drug Conjugates Regulated by Polypeptide‐PEG Derivative and Enhanced Antitumor Effect

Peptide‐drug conjugates (PDCs) are a type of self‐assembled prodrug with good potential for drug delivery due to their excellent biocompatibility, high drug loading, and permanent controllable release. However, most PDCs tend to self‐assemble into filamentous nanostructures in water and under physiological conditions, making them unsuitable as intravenous formulations due to the entanglement of long fibers and the risk of thrombus. Injected PDCs also face challenges in overcoming the complex physiological environment to reach the target site. To expand their clinical use, it is necessary to control the properties of PDC, including the self‐assembled structure and physiological performance, to avoid the above problems. Based on assembly mechanism studies of PDCs, a new method for regulating PDC morphology is developed by controlling intermolecular interactions in the assembly process. This method can alter the final morphology of PDCs from nanofibers to nanorods, and the introduced macromolecules endow the PDC with new characteristics that facilitate stable and high‐efficiency access to the target site.     

Low‐Dimensional Lead‐Free Inorganic Perovskites for Resistive Switching with Ultralow Bias

3D organic–inorganic and all‐inorganic lead halide perovskites have been intensively pursued for resistive switching memories in recent years. Unfortunately, instability and lead toxicity are two foremost challenges for their large‐scale commercial applications. Dimensional reduction and composition engineering are effective means to overcome these challenges. Herein, low‐dimensional inorganic lead‐free Cs₃Bi₂I₉ and CsBi₃I₁₀ perovskite‐like films are exploited for resistive switching memory applications. Both devices demonstrate stable switching with ultrahigh on/off ratios (≈10⁶), ultralow operation voltages (as low as 0.12 V), and self‐compliance characteristics. 0D Cs₃Bi₂I₉‐based device shows better retention time and larger reset voltage than the 2D CsBi₃I₁₀‐based device. Multilevel resistive switching behavior is also observed by modulating the current compliance, contributing to the device tunability. The resistive switching mechanism is hinged on the formation and rupture of conductive filaments of halide vacancies in the perovskite films, which is correlated with the formation of AgI_x layers at the electrode/perovskite interface. This study enriches the library of switching materials with all‐inorganic lead‐free halide perovskites and offers new insights on tuning the operation of solution‐processed memory devices.     

Highly Efficient Multifunctional Supramolecular Gene Carrier System Self‐Assembled from Redox‐Sensitive and Zwitterionic Polymer Blocks

It has been a challenge to incorporate multiple features into a single gene carrier system to overcome numerous hurdles during the gene delivery. Herein, a supramolecular approach for building a multifunctional gene carrier system is demonstrated with the functions of disulfide bond based reduction‐responsive degradation and zwitterionic phosphorylcholine based extracellular stabilization and favorable cellular uptake. The gene carrier system is self‐assembled from two molecular building blocks: one host polymer, which is a redox‐sensitive β‐cyclodextrin based cationic star polymer, and one guest polymer, which is adamantyl end capped zwitterionic phosphorylcholine based polymer. The host and guest polymers self‐assemble to integrate multiple functions into one system, based on the host‐guest interaction between β‐cyclodextrin and adamantyl moieties. With the rational designs of both building blocks, the supramolecular gene carrier system possesses excellent protein stability, serum tolerance, cellular uptake and intracellular DNA release properties, and also low cytotoxicity. These features work simultaneously to achieve exceptionally high gene transfection efficiency, which is proven in MCF‐7 cell cultures using luciferase and green fluorescence protein reporter genes. Finally, the supramolecular gene carrier is applied to deliver the therapeutic p53 anti‐cancer gene in MCF‐7 cells, showing great potential for cancer gene therapy application.     

Multi‐model Switching for Car Navigation Containing Low‐Grade IMU and GPS Receiver

This letter presents a filter for a car navigation system integrating a low‐grade inertial measurements unit (IMU) and a global positioning system receiver. The filter is designed according to the state variables to be estimated and the usable measurements. The usable measurements change from case to case, and the estimative state variables also change due to the measurements; therefore, multiple models must be used for real environmental maneuvers. In this letter, four models for land navigation are chosen and switched by rearranging the system matrix and resetting the error covariance matrices.     

Direct Observation of Conducting Nanofilaments in Graphene‐Oxide‐Resistive Switching Memory

Determining the presence of conducting filaments in resistive random access memory with nanoscale thin films is vital to unraveling resistive switching mechanisms. Bistable resistive switching within graphene‐oxide (GO)‐based resistive memory devices, recently developed by many research groups, has been generally explained by the formation and rupture of conducting filaments induced by the diffusion of metal or oxygen ions. Using a low‐voltage spherical aberration‐corrected transmission electron microscopy (TEM), we directly observe metallic nanofilaments formed at the amorphous top interface layer with the application of external voltages in an Al/GO/Al memory system. Atomic‐resolution TEM images acquired at an acceleration voltage of 80 kV clearly show that the conducting nanofilaments are composed of nanosized aluminum crystalline within the amorphous top interface layer after applying a negative bias (ON state). Simultaneously, we observe the change in the crystallinity of GO films by the back‐diffusion of oxygen ions. The oxygen‐deficient regions are clearly confirmed by energy‐filtered TEM oxygen elemental mapping. This work could provide strong evidence to confirm the resistive switching mechanism previously suggested by our group.     

Tunable Photodynamic Switching of DArE@PAF‐1 for Carbon Capture

A new type of photodynamic carbon capture material with up to 26 wt% CO₂ desorption capacity is synthesized via incorporation of diarylethene (DArE) as guest molecules in porous aromatic framework‐1 (PAF‐1). In these host–guest complexes, the carboxylic acid groups featured in DArE allow multiple noncovalent interactions to exist. DArE loadings ranging from 1 to 50 wt% are incorporated in PAF‐1 and the complexes characterized by UV–vis spectroscopy, FT‐IR spectroscopy, CO₂, and N₂ adsorption. Successful inclusion of DArE in PAF‐1 is indicated by the reduction of pore size distributions and an optimum loading of 5 wt% is determined by comparing the percentage photo­response and CO₂ uptake capacity at 1 bar. Mechanistic studies suggest that photoswitching modulates the binding affinity between DArE and CO₂ toward the host, triggering carbon capture and release. This is the first known example of photodynamic carbon capture and release in a PAF.     

Templated Assembly of pH‐Labile Polymer‐Drug Particles for Intracellular Drug Delivery

The preparation of pH‐labile polymer‐drug particles via mesoporous silica‐templated assembly for anticancer drug delivery into cancer cells is reported. The polymer‐drug conjugate is synthesized via thiol‐maleimide click chemistry using thiolated poly(methacrylic acid) (PMA_SH) and a pH‐labile doxorubicin (Dox) derivative. Drug‐loaded polymer particles that are stable under physiological conditions are obtained through infiltration of the conjugates into mesoporous silica particles, followed by cross‐linking the PMA_SH chains, and subsequent removal of the porous silica templates. The encapsulated Dox is released from the particles through cleavage of the hydrazone bonds between Dox and PMA_SH at endosomal/lysosomal pH. Cell viability assays show that the assembled PMA_SH particles have negligible cytotoxicity to LIM1899 human colorectal cancer cells. In comparison, Dox‐loaded PMA_SH particles cause significant cell death following internalization. The reported particles represent a novel and versatile class of stimuli‐responsive carriers for controlled drug delivery.     

A Redox‐Triggered Bispecific Supramolecular Nanomedicine Based on Peptide Self‐Assembly for High‐Efficacy and Low‐Toxic Cancer Therapy

Polo‐like kinase 1 (PLK1) and polo‐like kinase 4 (PLK4) are closely associated with the progression of several cancers, and their bispecific inhibitors can kill tumor cells effectively. Herein, a redox‐responsive bispecific supramolecular nanomedicine based on the self‐assembly of a cyclic peptide, termed as C‐1, targeting both PLK1 and PLK4 as a potent anticancer agent is reported. C‐1 is a cyclic peptide in response to reducing agents such as glutathione (GSH), which is constructed by a combined approach of pharmacophore modeling, molecular docking, and reversible cyclization. After entering the cytosol of cancer cell, the disulfide linkage is reduced by intracellular GSH, with the resulting linear conformation self‐assembling into bispecific nanofibers. C‐1 can lead to apoptotic cell death by inducing caspase‐3 activation and PARP cleavage in HeLa cells. Moreover, it suppresses the growth of HeLa cells in cell assays, and inhibits the progression of HeLa cells‐induced xenografts in nude mice without inducing notable side effects. This work provides a successful example of developing the redox‐responsive bispecific nanomedicine for high‐efficacy and low‐toxic cancer therapy.     

Reversible Electroaddressing of Self‐assembling Amino‐Acid Conjugates

The triggered assembly of organic and biological materials in response to imposed electrical signals (i.e., electroaddressing) provides interesting opportunities for applications in molecular electronics, biosensing and nanobiotechnology. Recent studies have shown that the conjugation of aromatic moieties to short peptides often yields hydrogelator compounds that can be triggered to self‐assemble over a hierarchy of length scales in response to a reduction in pH. Here, we examined the capabilities of fluorenyl‐9‐methoxycarbonyl‐phenylalanine (Fmoc‐Phe) to electrodeposit in response to an electrochemically‐induced pH gradient generated at the anode surface. We report that the electrodeposition of Fmoc‐Phe; is rapid (minutes), can be spatially controlled in normal and lateral directions, and can be reversed by applying a brief cathodic current. Further more, we show that Fmoc‐Phe can be simultaneously deposited on one electrode address (anode) while it is being cathodically stripped from a separate electrode address of the same chip. Finally, we demonstrate that these capabilities can be extended for electroaddressing within microfluidic channels. The reversible assembly/disassembly of molecular gelators (Fmoc‐amino acids and Fmoc‐peptides) in response to spatiotemporally imposed electrical signals offers unique opportunities for electroaddressing that should be especially valuable for lab‐on‐a‐chip applications.     

Origin of the Ultra‐nonlinear Switching Kinetics in Oxide‐Based Resistive Switches

Experimental pulse length–pulse voltage studies of SrTiO₃ memristive cells are reported, which reveal nonlinearities in the switching kinetics of more than nine orders of magnitude. The results are interpreted using an electrothermal 2D finite element model. The nonlinearity arises from a temperature increase in a few‐nanometer‐thick disc‐shaped region at the Ti electrode and a corresponding exponential increase in oxygen‐vacancy mobility. The model fully reproduces the experimental data and it provides essential design rules for optimizing the cell concept of nanoionic resistive memories. The model is generic in nature: it is applicable to all those oxides which become n‐conducting upon chemical reduction and which show significant ion conductivity at elevated temperatures.     

Template‐Assisted Self‐Assembly of Spherical Colloids into Complex and Controllable Structures

Colloidal aggregates with well‐controlled sizes, shapes, and structures have been fabricated by dewetting aqueous dispersions of monodispersed spherical colloids across surfaces patterned with two‐dimensional arrays of relief structures (or templates). The capability and feasibility of this approach have been demonstrated with the organization of polymer latex or silica beads into homo‐aggregates, including circular rings; polygonal and polyhedral clusters; and linear, zigzag, and spiral chains. It was also possible to generate hetero‐aggregates in the configuration of HF and H₂O molecules that contained spherical colloids of different sizes, compositions, densities, functions, or a combination of these features. These uniform, well‐defined aggregates of spherical colloids are ideal model systems to investigate the aerodynamic, hydrodynamic, and optical properties of colloidal particles characterized by non‐spherical shapes and/or complex topologies. They can also serve as a new class of building blocks to generate hierarchically self‐assembled structures that are expected to exhibit interesting features valuable to areas ranging from condensed matter physics to photonics.