Recent advances in self-assembled nanoplatforms for central nervous system disorders therapy: Design principles, multifunctional strategies, and therapeutic applications.

Highly ordered pore channels can effectively improve mass transport in porous electrodes. However, due to the inherent trade-off between high porosity and structural regularity, achieving an ordered pore channel in practical highly porous electrode materials remains a challenge. To address this issue, we present a simple but highly efficient colloidal self-assembly (SA) route that is capable of constructing various ordered structures. By sedimentation-driven SA, we demonstrate that nematic liquid crystal (LC) carbon ring electrodes can be achieved. The electrodes are self-standing and binder-free. In particular, they have directional macropore channels aligned along the electrode direction and exhibit a high discharge specific capacity of up to 32785 mAh g-1 in Li-O2 batteries. This represents a 60% improvement compared to the disordered counterpart under the same conditions. As we demonstrated, the discharge specific capacities have a strong positive correlation with the degree of orientational order of carbon rings in the electrodes. The superior electrochemical performance can be attributed to the synergistic effect of directional Li-ion transport, more uniform junction distribution, and more uniform electric field distribution, which are brought about by the nematic LC structure. We expect to provide a new guideline for electrode structure design by using colloidal SA to regulate electrode structures.

Supraparticles (SPs) are assemblies of smaller particles, and they form an interesting material class. One way through which these structures can be formed is self-assembly (SA) in spherical confinement, and what makes them unique is that they combine the properties of the smaller particles with collective properties arising from the length scale on which these smaller particles are ordered. Additionally, the limited number of particles in an SP enables them to form structures that are not found in bulk systems. An example of this is icosahedral symmetry, which is the equilibrium structure for SPs up to several hundreds of thousands of particles. Although these icosahedral structures have been investigated through computer simulations and several experimental techniques have been used to analyze them in 3D, the number of experimental datasets published is so limited that no statistically relevant conclusions have been drawn so far. The experimental technique most commonly applied to study them is scanning electron microscopy (SEM), but with this, only quantitative information about the surface of the SPs can be obtained. By using a combination of 3D confocal and stimulated emission depletion (STED) microscopy on extremely well-index-matched (within 0.002) fluorescent core-shell, colloidal silica spheres (of 442-478 nm in diameter with polydispersities below 1%), we obtained full 3D real-space datasets of tens of SPs within several hours. The structures were classified based on bond order parameters and deviations from local centrosymmetry, using an unsupervised machine learning model. From this, we are able to correctly classify structures that are commonly misidentified using SEM. Additionally, the quantitative real-space analysis gave experimental insights into the SA pathway and defect formation mechanisms of mostly icosahedral SPs.

This review surveys SERS and SEF spectroscopies, with a spotlight on the correlation between nanogap fabrication techniques and subsequent applications of those nanogaps in biosensing. In the last several decades, the development of new nanofabrication techniques and novel applications substantially increased the importance of these spectroscopic techniques for biosensing. The cornerstone of this development is the application and control of nanogaps between nanoparticles and nanostructures. Nanogaps are important since they may be responsible for the biggest portion of signal enhancement in SERS and SEF. This review summarizes and provides insights into the theory behind nanogap enhancement, nanogap fabrication, and its applications in direct and indirect biosensing. The theoretical part includes studies on the origin of nanogap enhancement and its dependence on gap distance and agglomeration. Next, the review presents and compares structured and unstructured fabrication techniques with a few dozen examples tabulated with their figures of merit, like the enhancement factor (EF) and limit of detection (LOD). In total, 50 SERS-based and 26 SEF-based articles were tabulated, whereas 38 papers were classified based on the synthesis method and based on the EF and median LOD values calculated for Electron Beam Lithography (EBL) and Template-Assisted (TA) prepared substrates that were no more than one order of magnitude better or about the same as those for other fabrication methods (median 1 × 10-10 and 8 × 10-10 M for EBL and TA, respectively, vs. median 4 × 10-8 and 1 × 10-9 M for nanosphere lithography (NSL) and Self-Assembly (SA), respectively). The median EF for substrates fabricated with EBL, NSL, and TA methods (4.6 × 108, 1.0 × 108, and 1.4 × 108) demonstrates only a moderate advantage over the SA technique, with a median EF of 0.3 × 108. However, unstructured nanofabrication techniques like self-assembly have a more affordable price, lower complexity, and better scalability. Therefore, SA can easily compete with ordered nanofabrication techniques. In addition, this review also highlights the applications of nanogaps in label-free detection and biomarker detection. Finally, this review highlights applications of nanogap enhancement in SEF and draws conclusions on the current state of nanogap research and its future.

Solution-based soft matter self-assembly (SA) promises unique material structures and properties from approaches including additive manufacturing/three-dimensional (3D) printing. The 3D printing of periodically ordered porous functional inorganic materials through SA unfolding during printing remains a major challenge, however, due to the often vastly different ordering kinetics of separate processes at different length scales. Here, we report a “one-pot” direct ink writing process to produce hierarchically porous transition metal nitrides and precursor oxides from block copolymer (BCP) SA. Heat treatment protocols identified in various environments enable mesostructure retention in the final crystalline materials with periodic lattices on three distinct length scales. Moreover, embedded printing enables the first BCP directed mesoporous non-self-supporting helical oxides and nitrides. Resulting nitrides are superconducting, with record nanoconfinement-induced upper critical fields correlated with BCP molar mass and record surface areas for compound superconductors. Results suggest scalable porous functional inorganic material formation approaches for applications including catalysis, sensing, and microelectronics.

Self-assembly (SA) plays a pivotal role in nanotechnology, offering cost-effective methods for bottom-up fabrication and providing versatile model systems for investigating fundamental interactions in various bioinspired systems. However, current methods for investigating and quantifying the dynamics of SA systems are limited in their applicability to planar interfaces, particularly in liquid environments. These methods typically rely on analyzing the collective behavior of particle suspensions rather than directly probing the specific interactions between individual particles. Here, we introduce Casimir self-assembly (CaSA) as a platform, integrating colloidal science, nanophotonics, and fluctuational electrodynamics to study long-range interactions and stability in planar SA systems. Using thermal fluctuations as a probe and visible-range Fabry-Pérot resonances as an optical readout, we demonstrate that CaSA enables a direct in situ study of the Casimir-Lifshitz electrostatic interaction. This approach allows us to map stability regimes of colloidal materials by varying ionic strength and identifying conditions for stable assembly and aggregation limits, and moreover is used to measure the surface charge density of an individual colloidal object down to fractions of an electron charge per square nanometer. Our platform overcomes the limitations of current methods, providing an experimental tool for exploring SA dynamics in situ and expanding the understanding of suspension stability in liquids at the single-particle level. With potential for future applications, CaSA is scalable for studying interfacial forces and is adaptable to multivalent electrolytes and biosensing.

Interface in the metal (Me)-C60 multilayer (ML) appears to be a unique means of controlling local electronic and magnetic properties of hybrid materials. The remarkable ability of the interface is discussed by Al Ma’Mari et al. (Nature 524:69, 2015), where a ferromagnetic (FM) state of the Cu-C60 ML hybrid was found. In this work, we report the discovery of stable FM effects in the self-assembled (SA) CuxC60 hybrid system possessing a large and controllable fraction of self-organized interface formed between single-crystal Cu nanoparticles and the C60 medium. Using SQUID magnetometry, we were able to confidently establish the magnetization hysteresis loops, which reflect the FM state of the SA CuxC60 hybrids even at room temperature. By applying the SA hybrid model, we performed the relevant normalizations of the magnetic curves, which allowed us to prove the decisive role of the interface Cu atoms in the FM magnetism of the SA hybrids. Field cooling (FC) of the SA sample to 2 K in the field of 1 T revealed a specific shift in the hysteresis loop, reflecting the exchange bias effect in the SA hybrid system. The anomalous increase in saturation magnetization in the SA hybrid after FC treatment indicates the magnetic effect of the C60 monolayer pinned to the interfacial FM Cu layer by the exchange bias field. The obtained results designate the SA CuxC60 hybrids as multifunctional materials with tunable magnetism, promising for use in effective sensors and memory devices.

Abstract Covalent organic frameworks (COFs), a class of porous polymers with tunable 2D or 3D structures, have drawn significant attention for their exceptional versatility across various applications. Recently, the integration of COFs into perovskite solar cells (PSCs) has emerged as a promising strategy to address critical challenges, such as instability, interfacial recombination losses, and lead‐associated environmental risks. Enhanced charge transport channels, passivation of defects, and customizable molecule architectures are some of the special benefits that COFs offer. In this study, we used Schiff base reactions to create two donor–acceptor (D‐A) type COFs with an 8+2 connection motif, which were integrated into PSC self‐assembled (SAM) layers. According to characterizations and theoretical calculations, COFs not only effectively optimize the energy level of the ITO/SAM substrate but also passivate perovskite defects and suppress defect‐assisted recombination in PSC devices. These modifications significantly enhanced carrier transport and extraction, resulting in an increase in power conversion efficiency (PCE) from 22.57% to 25.20% (DP‐BE) and 24.21% (DP‐DBE). This work highlights the potential of COFs as multifunctional modifiers for interfacial engineering in PSCs, offering a promising route to improve device performance and stability.

Covalent organic frameworks (COFs), a class of porous polymers with tunable 2D or 3D structures, have drawn significant attention for their exceptional versatility across various applications. Recently, the integration of COFs into perovskite solar cells (PSCs) has emerged as a promising strategy to address critical challenges, such as instability, interfacial recombination losses, and lead-associated environmental risks. Enhanced charge transport channels, passivation of defects, and customizable molecule architectures are some of the special benefits that COFs offer. In this study, we used Schiff base reactions to create two donor-acceptor (D-A) type COFs with an 8+2 connection motif, which were integrated into PSC self-assembled (SAM) layers. According to characterizations and theoretical calculations, COFs not only effectively optimize the energy level of the ITO/SAM substrate but also passivate perovskite defects and suppress defect-assisted recombination in PSC devices. These modifications significantly enhanced carrier transport and extraction, resulting in an increase in power conversion efficiency (PCE) from 22.57% to 25.20% (DP-BE) and 24.21% (DP-DBE). This work highlights the potential of COFs as multifunctional modifiers for interfacial engineering in PSCs, offering a promising route to improve device performance and stability.

The self-assembly (SA) of colloidal nanoparticles (NPs) into superstructures provides a versatile and promising method for manipulating the nanometer-sized particles and exploiting their unique features. In pursuit of this objective, researchers have conceived, created, examined, and constructed microscopic entities of diverse intricacy with the intention of facilitating the assembly of desired phases. In this work, a simple method for fabricating a self-supported superstructure of bismuth nanoparticles (Bi NPs) is presented, in which nanoparticles are thermally reshaped into self-assembly from pre-synthesized bismuth nanoparticles. Observations with scanning and transmission electron microscopy revealed that smaller nanoparticles self-assembled anisotropically, followed by nanosheets and nanorods. Further, the anisotropic growth of bismuth nanoparticles increases as the temperature rises due to ligand rearrangement.

Abstract The creation of anisotropic nanoparticles (NPs) by polymerization and/or self‐assembly (SA) has significantly promoted the applications of polymer nanomaterials in many fields. However, polymer nanorods are not easily accessible via conventional polymerization or SA. Here we report a one‐step route to synthesize single‐domain smectic liquid crystalline (LC) nanorods utilizing oriented attachment (OA) that was usually found in the synthesis of inorganic NPs, synchronized with polymerization and SA. The synchronization was achieved by developing a novel stabilizer derived from a thermo‐responsive polyelectrolyte system. Mechanistic studies reveal that controlling the thermo‐responsive behavior and the distribution of stabilizers on NPs enabled OA. The LC nanorods can further form hierarchical colloidal LCs, which show much larger light transmittance than that of non‐LC nanorods. Moreover, we demonstrate that this LC system can be manipulated by an external magnetic field, thus providing a candidate material for magnetic‐responsive display.

The creation of anisotropic nanoparticles (NPs) by polymerization and/or self-assembly (SA) has significantly promoted the applications of polymer nanomaterials in many fields. However, polymer nanorods are not easily accessible via conventional polymerization or SA. Here we report a one-step route to synthesize single-domain smectic liquid crystalline (LC) nanorods utilizing oriented attachment (OA) that was usually found in the synthesis of inorganic NPs, synchronized with polymerization and SA. The synchronization was achieved by developing a novel stabilizer derived from a thermo-responsive polyelectrolyte system. Mechanistic studies reveal that controlling the thermo-responsive behavior and the distribution of stabilizers on NPs enabled OA. The LC nanorods can further form hierarchical colloidal LCs, which show much larger light transmittance than that of non-LC nanorods. Moreover, we demonstrate that this LC system can be manipulated by an external magnetic field, thus providing a candidate material for magnetic-responsive display.

Creating hierarchical crystalline materials using simple colloids or nanoparticles is very challenging, as it is usually impossible to achieve hierarchical structures without nonhierarchical colloidal interactions. Here, we present a hierarchical self-assembly (SA) route that employs colloidal rings and anisotropic colloidal particles to form complex colloids and uses them as building blocks to form unusual colloidal columnar liquid crystals or crystals. This route is realized by designing hierarchical SA driving forces that is controlled by the colloidal shape and shape-dependent depletion attraction. Depletion-induced lock-and-key interaction is the first driving force, which ensures a high efficiency (>90%) to load colloidal particles of other shapes such as spheres, spherocylinders, and oblate ellipsoids into rings, providing high-quality building blocks. Their SA into ordered superstructures has to require a second driving force such as higher volume fraction and/or stronger depletion attraction. As a result, unusual hierarchical colloidal (liquid) crystals, which have previously been difficult to fabricate by simple binary assembly, can be achieved. This work presents a significant advancement in the field of hierarchical SA, demonstrating a promising strategy for constructing many unprecedented crystalline materials by the SA route.

Although bioactive compounds (BCs) have many important functions, their applications are greatly limited due to their own defects. The development of nanocarriers (NCs) technology has gradually overcome the defects of BCs. NCs are equally important as BCs to some extent. Self-assembly (SA) methods to build NCs have many advantages than chemical methods, and SA has significant impact on the structure and function of NCs. However, the relationship among SA mechanism, structure, and function has not been given enough attention. Therefore, from the perspective of bottom-up building mechanism, the concept of SA-structure-function of NCs is emphasized to promote the development of SA-based NCs. First, the conditions and forces for occurring SA are introduced, and then the SA basis and molecular mechanism of protein, polysaccharide, and lipid are summarized. Then, varieties of the structures formed based on SA are introduced in detail. Finally, facing the defects of BCs and how to be well solved by NCs are also elaborated. This review attempts to describe the great significance of constructing artificial NCs to deliver BCs from the aspects of SA-structure-function, so as to promote the development of SA-based NCs and the wide application of BCs.

Carbohydrate-based self-assembling systems are essential for the formation of advanced biocompatible materials via a bottom-up approach. The self-assembling of sugar-based small molecules has applications encompassing many research fields and has been studied extensively. In this focused review, we will discuss the synthetic approaches for carbohydrate-based self-assembling (SA) systems, the mechanisms of the assembly, as well as the main properties and applications. This review will mainly cover recent publications in the last four years from January 2020 to December 2023. We will essentially focus on small molecule self-assembly, excluding polymer-based systems, which include various derivatives of monosaccharides, disaccharides, and oligosaccharides. Glycolipids, glycopeptides, and some glycoconjugate-based systems are discussed. Typically, in each category of systems, the system that can function as low molecular weight gelators (LMWGs) will be discussed first, followed by self-assembling systems that produce micelles and aggregates. The last section of the review discusses stimulus-responsive self-assembling systems, especially those forming gels, including dynamic covalent assemblies, chemical-triggered systems, and photoresponsive systems. The review will be organized based on the sugar structures, and in each category, the synthesis of representative molecular systems will be discussed next, followed by the properties of the resulting molecular assemblies.

Traditional carbon capture and storage technologies for large point sources can at best slow the rate of increase in atmospheric CO2 concentrations. In contrast, direct capture of CO2 from ambient air, or "direct air capture" (DAC), offers the potential to become a truly carbon-negative technology. Composite solid adsorbents fabricated by impregnating a porous matrix with K2CO3 are promising adsorbents for the adsorption capture of CO2 from ambient air. Nevertheless, the adsorbent can be rapidly deactivated during continuous adsorption/desorption cycles. In this study, MgO-supported, TiO2-stabilized MgO@TiO2 core-shell structures were prepared as supports using a novel self-assembled (SA) method and then impregnated with 50 wt % K2CO3 (K2CO3/MgO@TiO2, denoted as SA-KM@T). The adsorbent exhibits a high CO2 capture capacity of ∼126.6 mg CO2/g sorbent in direct air adsorption and maintained a performance of 20 adsorption/desorption cycles at 300 °C mid-temperature, which was much better than that of K2CO3/MgO. Analysis proved that the core-shell structure of the support effectively inhibited the reaction between the active component (K2CO3) and the main support (MgO) by the addition of TiO2, resulting in higher reactivity, thermal stability, and antiagglomeration properties. This work provides an alternative strategy for DAC applications using adsorbents.

Self-assembly (SA) structures are formed by self-organizing processes in which discrete elements interact spontaneously with one another to produce larger and more complex structures. Compared to disorganized systems, self-assembled nanoparticles with specific functionalities can exhibit enhanced or even novel properties. Among the various nanoparticles capable of forming SAs, we can highlight carbon quantum dots (Cdots). Cdots are photoluminescent core/shell semiconductor nanoparticles with excellent optical properties, such as photo-stability, size-dependent emission energy, and intensity sensitivity to particle aggregation. Thus, the organization of individual Cdots in ordered structures on solid substrates has the potential for possible nanodevices in the area of sensors, catalysis, optoelectronics, and data storage. This study aimed to produce Cdots-based SAs and subsequently study their morphological and optical properties. Cdots were obtained by electrochemical exfoliation of the graphite electrode, and SA structures were obtained by the induced evaporation method under controlled temperature. The effects of the temperature and volume of the deposited Cdots solution in the substrate on the formation of SA were investigated. Optical and fluorescence microscopy images showed the formation of photoluminescent SA structures up to 1 mm in size with different aggregation patterns, such as aggregation by limited diffusion, river-type fractal, fern-leaf-type fractal, films, and bifurcated patterns. The variation of the parameters caused significant changes in some characteristics of the SAs structures, such as an increase in the intensity of the photoluminescence (PL) or its annihilation and change in the self-organization pattern. The results obtained in this work provide a preliminary overview of the different patterns of SA structures that can be obtained using photoluminescent Cdots as building blocks.

The manipulation of single molecules has attracted extensive attention because of their promising applications in chemical, biological, medical, and materials sciences. Optical trapping of single molecules at room temperature, a critical approach to manipulating the single molecule, still faces great challenges due to the Brownian motions of molecules, weak optical gradient forces of laser, and limited characterization approaches. Here, we put forward localized surface plasmon (LSP)-assisted trapping of single molecules by utilizing scanning tunneling microscope break junction (STM-BJ) techniques, which could provide adjustable plasmonic nanogap and characterize the formation of molecular junction due to plasmonic trapping. We find that the plasmon-assisted trapping of single molecules in the nanogap, revealed by the conductance measurement, strongly depends on the molecular length and the experimental environments, i.e., plasmon could obviously promote the trapping of longer alkane-based molecules but is almost incapable of acting on shorter molecules in solutions. In contrast, the plasmon-assisted trapping of molecules can be ignored when the molecules are self-assembled (SAM) on a substrate independent of the molecular length.

The present article demonstrates the fabrication of various β-Gallium Oxide (Ga2O3) nanostructures (NSs) by low-cost and scalable electrospraying (ES) methods via self-assembly (SA). The effect of the annealing sequences on the self-assembled β-Ga2O3 NSs has been detailed. The comparative studies of NSs and nanoflakes (NFs) growth with annealing effect at different stages of self-assembly time (SAT) have been explored further. The fabricated NSs and NFs have been investigated using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The comparative study of categorized growth samples shows better crystalline quality when moving from the category 1 (C1) sample to the category 3 (C3) sample. The annealing sequences with SAT play a significant role in crystal formation and its quality, optical properties, and morphology of the Ga2O3 NSs. The optical properties of NSs have been derived from the normal incidence of absorbance measurements. The maximum observed energy band gap is ~ 5.40 eV. Traps and impurities play a critical role in the formation and deformation of energy bands in crystals. The photoluminescence spectra further reveal the variation in the intensity of luminescence of different emission bands due to the variation in the number of defect states and impurities in the NSs.

A multistep assembly of gold nanoparticle self-assembled monolayers (SAMs) on glass surfaces is proposed, as a third-year undergraduate experiment. The process includes self-assembly (SA) and electrostatic self-assembly (ESA) methods, which are central approaches in modern surface and materials engineering. The products are analyzed using spectrophotometry and contact angle measurements. The experiment can be completed in a standard 4 h teaching laboratory session.