Self-assembled Structures Research Articles

Structure and dynamics of amphiphilic patchy cubes in a nanoslit under shear.

Patchy nanocubes are intriguing materials with simple shapes and space-filling and multidirectional bonding properties. Previous studies have revealed various mesoscopic structures such as colloidal crystals in the solid regime and rod-like or fractal-like aggregates in the liquid regime of the phase diagram. Recent studies have also shown that mesoscopic structural properties, such as an average cluster size M and orientational order, in amphiphilic nanocube suspensions are associated with macroscopic viscosity changes, mainly owing to differences in cluster shape among patch arrangements. Although many studies have been conducted on the self-assembled structures of nanocubes in bulk, little is known about their self-assembly in nanoscale spaces or structural changes under shear. In this study, we investigated mixtures of one- and two-patch amphiphilic nanocubes confined in two flat parallel plates at rest and under shear using molecular dynamics simulations coupled with multiparticle collision dynamics. We considered two different patch arrangements for the two-patch particles and two different slit widths H to determine the degree of confinement in constant volume fractions in the liquid regime of the phase diagram. We revealed two unique cluster morphologies that have not been previously observed under bulk conditions. At rest, the size of the rod-like aggregates increased with decreasing H, whereas that of the fractal-like aggregates remained constant. Under weak shear with strong confinement, the rod-like aggregates maintained a larger M than the fractal-like aggregates, which were more rigid and maintained a larger M than the rod-like aggregates under bulk conditions.

Coarse-grained molecular simulation of the effect of liquid crystal molecular pitch on structure in cylindrical confinement.

Blue phases (BPs) consist of three-dimensional self-assembled structures formed by a double-twisted columnar arrangement of liquid crystal molecules. Although their unique optical and structural properties render BPs particularly useful for applications such as liquid crystal displays, BPs typically appear in a narrow temperature range between the isotropic and nematic phases. This thermodynamic instability impedes their practical applicability. However, the simulations we present here showed that, in a quasi-one-dimensional system confined to nanospace, a phase equivalent to the BP appears and persists between the nematic and smectic phases. Confinement to a nanotube (NT) with a relatively small radius enables the BP to be maintained over a wide temperature range, whereas for an NT with a relatively larger radius, the BP appears only in a very narrow temperature range between the aforementioned phases. We additionally showed that the pitch of the BP is dependent on and can be controlled by adjusting the radius of the NTs. This finding has significant implications for the potential application of these materials in fields such as photonics and chiral separation technologies.

Atomistic Molecular Dynamics Simulations of ABA-Type Polymer Peptide Conjugates: Insights into Supramolecular Structures and their Circular Dichroism Spectra.

A combination of atomistic molecular dynamics (aMD) simulations and circular dichroism (CD) analysis is used to explore supramolecular structures of amphiphilic ABA-type triblock polymer peptide conjugates (PPC). Using the example of a recently introduced PPC with pH- and temperature responsive self-assembling behavior [Otter etal., Macromolecular Rapid Communications 2018, 39, 1800459], this study shows how molecular dynamics simulations of simplified fragment molecules can add crucial information to CD data, which helps to correctly identify the self-assembled structures and monitor the folding/unfolding pathways of the molecules. The findings offer insights into the nature of structural transitions induced by external stimuli, thus contributing to the understanding of the connection of microscopic structures with macroscopicproperties.

Topological hydrogen-bonded organic frameworks (HOFs) and their electronic applications in sensor, memristor, and neuromorphic computing

Recently, an emerging class of hydrogen-bonded organic frameworks (HOFs) has become an appealing member of organic material family, attributed to their layered self-assembly structures, high-crystalline, and environmentally friendly characteristics, which have rapidly propelled their development in the field of electronic devices. In this context, we focus on the latest category of topological HOFs, with particular attention given to cutting-edge experimental demonstrations, exceptional electrical performances, and promising applications. First, a concise concept and fundamental mechanism of HOFs are provided, elucidating the potential correlation between structural designs and material properties. Subsequently, a comprehensive summary is presented on the preparation and synthesis methods, such as hydrothermal techniques, epitaxial growth, electro-deposition, among others. Notably, the latest advancements in HOFs-based electronics are thoroughly introduced and discussed, along with their applications in sensors, memristors, artificial synapses, neuromorphic computing, and human perception systems. Finally, the future challenges and prospects of topological HOFs are elaborated upon with the aim of providing valuable guidance for high-performance HOF-based electronics.

Montmorillonite restricts free fatty acid liberation and alters self-assembled structures formed during in vitro lipid digestion

The global rise in obesity necessitates innovative weight loss strategies. Naturally occurring smectite clays, such as montmorillonite (MMT), offer promise due to their unique properties that interfere with free fatty acid (FFA) liberation, reducing systemic uptake. However, the mechanisms of MMT-FFA interactions and their implications for weight management are undefined. This study investigates these interactions by adding MMT (10 % w/w) to in vitro lipolysis media containing medium chain triglycerides (MCTs), and monitoring FFA liberation using pH-stat titration. Nanoparticle tracking analysis (NTA) and synchrotron-based small-angle X-ray scattering (sSAXS) observed time-dependent structural changes, while electron microscopy examined clay morphology during digestion. A 35 % reduction in FFA liberation occurred after 25 min of digestion with MCT + MMT, with digestion kinetics following a biphasic model driven by calcium soap formation. NTA revealed a 17-fold decrease in vesicular structures with MCT + MMT, and sSAXS highlighted a rapid lamellar phase evolution linked to calcium soap formation. This acceleration is attributed to MMT's adsorption to unionized FFAs via hydrogen bonding, supported by TEM images showing a decrease in d-spacing, indicating FFA intercalation is not the main adsorption mechanism. These findings highlight MMT's potential as a novel intervention for reducing dietary lipid absorption in obesity and metabolic diseases.

Regulated the aggregation of bile salts by β-Cyclodextrin and Tangeretin at the oil-water interface for inhibiting lipid digestion

Our previous research has demonstrated that the changes in oil-water interface properties during dietary digestion have a significant impact on the digestion and absorption of lipids. In this study, these methods of interfacial tension, microscopic examination, isothermal titration calorimetry (ITC), molecular dynamics (MD) simulations, and free fatty acid (FFA) release were used to evaluate the effect and mechanism of assembly behavior of tangeretin (TAN) and β-cyclodextrin (β-CD) at the oil-water interface on the rate of lipid digestion. The results showed that the combination of β-CD and TAN at the oil-water interface made the interfacial tension first increase and then decrease with the increase of TAN: β-CD ratios (M: M, 1:1–20). The self-assembled structure formed by the interaction of TAN and β-CD can produce stronger interaction with bile salts, which makes bile salts flocculate at the oil-water interface. The FFAs release experiment showed that a TAN: β-CD molar ratio of 1:8 exerted the highest inhibitory (34.92%) effect on lipid digestion. Furthermore, the results from ITC and MD simulations confirmed that BS exhibited stronger binding affinity with the TAN/β-CD complex. These results suggested that the TAN/β-CD complex caused the bile salts to prematurely gather at the oil-water interface, thereby thickening the interfacial layer, hindering the displacement of bile salts and lipase between droplets, and ultimately impeding lipid digestion. This study emphasized the promising potential of the synergistic effect between cyclodextrin and flavoring molecules in inhibiting lipid digestion, proposing a novel avenue for the development of reduced-fat foods with enhanced health benefits.

Synthesis of self-assembled spherical ZnFe2O4 nanomaterials by the premixed stagnation flame method for highly sensitive acetone sensor

The efficient and reliable detection of acetone is critical for industrial safety, environmental monitoring, and human health. Separately, ZnFe2O4 particles were synthesized by using the premixed stagnation flame method and the co-precipitation method. The premixed stagnation flame method was used to create self-assembled spherical ZnFe2O4 nanoparticles with uniform morphology, polycrystalline morphology, and excellent phase purity. The effect of the gas-sensitive performance of these sensors for two routes on acetone vapor was compared. The sensor synthesized using the premixed stagnation flame method had a response value of up to 26 at 235°C for 100 ppm acetone vapor. It revealed outstanding reproducibility, stability, and selectivity for acetone vapor, which is attributed to the 10 nm "lychee-like" particle structure uniformly dispersed on the surface of the 400–500 nm spherical particles, forming a unique self-assembled structure. The self-assembled spherical structure has a large specific surface area, abundant oxygen adsorption, and oxygen vacancies, which effectively increases the reaction sites and electron mobility inside and outside the nanoparticles. The premixed stagnation flame method of producing spherical ZnFe2O4 nanoparticles presents a viable method for developing extremely sensitive, fast-responding, and selective acetone vapor sensors.

Modulation of Triton X-100 Aqueous Micelle Interface by Ionic Liquid: A Molecular Level Interaction Studied by Time-resolved Fluorescence Spectroscopy

Background: Self-assembly structure is an important area of research for understanding biological systems, owing to its resemblance to the membrane structure of the phospholipid bilayer. In a self-assembly medium, chemical reactions and chemical or physical processes are dramatically different than the bulk phase. Understanding this process in synthesizing self-assembly structures may allow us to explore various biological processes occurring in cell membranes. Objective: The study aimed to understand water dynamics in the TX-100 micellar interface via steady state and a time-resolved fluorescence spectroscopy study. The objective was also to determine the two different ionic liquids (ILs), namely 1-butyl-3-methyl imidazolium tetrafluoroborate ([bmim][BF4]) and 1-decyl-3-methyl imidazolium tetrafluoroborate ([dmim][BF4]), inducing surfactant aggregation changes at the molecular level. Also, the focus was on determining the hydration and its dynamics at the palisade layer of TX-100 micelle in the presence of two different ionic liquids. Methods: Steady state and time-resolved fluorescence spectroscopy have been used to study TX-100 micellar systems. Employing time-resolved spectroscopy, two chemical dynamic processes, solvation dynamics and rotational relaxation dynamics, have been studied to investigate structural changes in TX100 by adding ILs. Solvation dynamics was studied by measuring the time-dependent Stokes shift of the fluorescent probe. From the Stokes shift, time-resolved emission spectra were constructed to quantify the solvation dynamics. Also, using the polarization properties of light, time-resolved anisotropy was constructed to explore the rotation relaxation of the probe molecule. Results: The absorption and emission spectra of C-153 in TX-100 were red-shifted in the presence of both the ILs. Also, the C-153 experienced faster solvation dynamics and rotational relaxation with the addition of both ILs. In our previous study, we observed a significantly increased rate of solvation dynamics with the addition of [bmim][BF4] (J. Phys. Chem. B, 115, 6957-6963) [38]. However, with the addition of the same amount of [dmim][BF4], the IL rate of solvation enhancement was more pronounced than with [bmim][BF4]. The faster solvation and rotational relaxation have been found to be associated with the penetration of more free water at the TX100 micellar stern layer, leading to increased fluidity of the micellar interface. Conclusion: Upon incorporating ILs in TX100 micelle, substantially faster solvation dynamics of water as well as rotational relaxation dynamics of C-153 have been observed. By decreasing surfactant aggregations, [bmim][BF4] ILs facilitated more water molecules approaching the TX-100 micellar phase. On the other hand, [dmim][BF4] ILs comprising mixed micelles induced even more free water molecules at the palisade layer, yielding faster solvation dynamics in comparison to pure TX-100 micelle or TX100 micelle + [bmim][BF4] ILs systems. Time-resolved anisotropy study has also supported the finding and strengthened the solvation dynamics observation.

Self-assembled oligomeric structures of an asymmetric molecular linker; 4-isocyanophenyl disulfide on Au(111)

Para-substituted benzenes, such as 1,4-benzene dithiol and 1,4-phenyl diisocyanide, have been observed to oligomerize on the Au(111) surface by incorporating gold adatoms extracted from the substrate. This work investigates if oligomerization occurs for an analogous but asymmetric linker, 4-isocyanophenyl disulfide (ICPD) on Au(111). This molecule is comprised of both disulfide and isocyanide terminal groups attached to the phenyl ring. The resulting surface structures formed on Au(111) following exposure to ICPD are studied using scanning tunneling microscopy (STM). 1,4-isocyanophenyl thiolate (ICPT), formed through scission of ICPD’s disulfide bond, was also found to oligomerize on the surface, and potential oligomer structures and binding geometries are proposed with the aid of density functional theory (DFT) calculations, along with simulated STM images of the resulting structures. It is observed in this work that ICPT forms oligomeric structures that cover large sections of the substrate and appear to create etch pits resulting from gold atom extraction. Numerous potential binding geometries are investigated based on the distances between substrate gold atom adsorption sites compared to the monomer length. Selected structural candidates were optimized using DFT and were used to generate simulated STM images using the Tersoff–Hamann method to compare with experiment. It has been shown previously that the isocyanide- and thiol-connected oligomers conduct electrons, suggesting the possibility that the asymmetric oligomers found here might form the basis for fabricating molecular diodes.

Minimum number of oligonucleotide-based stable monomeric branched DNA nanostructure: Biochemical and biophysical study

DNA has been employed as building blocks for the construction of nanomaterials due to their programmability and wide range applications. The functional branched DNA (bDNA) nanostructure is largely dependent on the sequence and structural symmetry. Despite the discovery of different structures, the synthesis of bDNA nanostructures from optimal number of oligonucleotides is yet to be explored. In the current study, for the first time we demonstrate the designing of stable monomeric bDNA structures using two or three oligonucleotides. Furthermore, the stability of bDNA nanostructures was thoroughly investigated in presence of different pH, cations, fetal bovine serum and DNase I. The thermodynamic parameters indicated that hydrogen bonding and van der Waals interactions played a major role during self-assembly of bDNA nanostructures. From the gel retardation assay, we confirmed the binding of complementary oligonucleotides to the bDNA nanostructures, thus can be explored for target specific transcript regulation. In conclusion, the self-assembled DNA nanostructures developed from optimal oligonucleotides are stable in physiological environment and can be used for biomedical applications.

Self-Responsive Fluorescence Aptasensor for Lactoferrin Determination in Dairy Products.

In this study, a self-responsive fluorescence aptasensor was established for the determination of lactoferrin (Lf) in dairy products. Herein, the aptamer itself functions as both a recognition element that specifically binds to Lf and a fluorescent signal reporter in conjunction with fluorescent moiety. In the presence of Lf, the aptamer preferentially binds to Lf due to its specific and high-affinity recognition by folding into a self-assembled and three-dimensional spatial structure. Meanwhile, its reduced spatial distance in the aptamer-Lf complex induces a FRET phenomenon based on the quenching of 6-FAM by amino acids in the Lf protein, resulting in a turn-off of the fluorescence of the system. As a result, the Lf concentration can be determined straightforwardly corresponding to the change in the self-responsive fluorescence signal. Under the optimized conditions, good linearities (R2 > 0.99) were achieved in an Lf concentration range of 2~10 μg/mL for both standard solutions and the spiked matrix, as well as with the desirable detection limits of 0.68 μg/mL and 0.46 μg/mL, respectively. Moreover, the fluorescence aptasensor exhibited reliable recoveries (89.5-104.3%) in terms of detecting Lf in three commercial samples, which is comparable to the accuracy of the HPCE method. The fluorescence aptasensor offers a user-friendly, cost-efficient, and promising sensor platform for point-of-need detection.

Theoretical Analysis of Coordination Geometries in Transition Metal-Histidine Complexes Using Quantum Chemical Calculations.

A theoretical investigation utilizing density functional theory (DFT) calculations was conducted to explore the coordination complexes formed between histidine (His) ligands and various divalent transition metal ions (Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+). Conformational exploration of the His ligand was initially performed to assess its stability upon coordination. Both 1:1 and 1:2 of metal-to-ligand complexes were scrutinized to elucidate their structural features and the relative stability of the complexes. This study examined the ability of His to act as a bidentate or tridentate coordinating ligand, along with the differences in coordination geometry when solvent effects were incorporated. The reduced density gradient (RDG) analysis and local electron attachment energy (LEAE) analysis were employed to elucidate the interaction planes and the nucleophilic and electrophilic properties. The electronic properties were analyzed through electrostatic potential (ESP) maps and natural population analysis (NPA) of atomic charge distributions. This computational study provides valuable insights into the diverse coordination modes of His and its interactions with divalent transition metal ions, contributing to a better understanding of the role of this amino acid ligand in the formation of transition metal complexes. The findings can aid in the design and construction of self-assembled structures involving His-metal coordination.

An Insight into Cubosomal Drug Delivery Approaches: An Explicative Review.

Cubosomes, a novel drug delivery system, have gained significant attention in recent years due to their unique self-assembled structures and enhanced drug encapsulation capabilities. They are administered by oral, ophthalmic, transdermal, and chemotherapeutic routes, to name a few. Due to their many potential benefits-which include high drug dispersal due to the cubic structure, a large surface area, a relatively simple manufacturing process, biodegradability, the capacity to encapsulate hydrophobic, hydrophilic, and amphiphilic compounds, targeted and controlled release of bioactive agents, and the biodegradability of lipids-cubosomes show enormous promise in drug nanoformulations for cancer therapeutics. The most common preparation method involves emulsifying a monoglyceride with a polymer, homogenizing, and then sonicating the mixture. Two distinct approaches to preparing are top-down and bottom-up. This evaluation will examine the materials, methods of preparation, cubosome-related drug encapsulating techniques, drug loading, release mechanism, and their uses. The following databases were used for literature searches: PubMed, Frontiers, Science Direct, Springer, Wiley, and MDPI. For the purpose of finding pertinent articles and contents (2015-2024), the keywords "cubosome; drug delivery systems, nano-carrier, theranostic, drug release mechanism" and others of a similar nature were utilized. This review will conduct a comprehensive analysis of the cubosome-related composition, production methods, drug encapsulating strategies, drug release mechanisms, and applications. Moreover, the difficulties encountered in fine-tuning different parameters to improve loading capabilities and prospects are also discussed. Innovation in pharmaceutical research and development can be stimulated by the knowledge gathered about cubosomal drug delivery methods. Through the clarification of the mechanisms involved in drug release from cubosomes and the investigation of innovative fabrication procedures, scientists can enhance the cubosomal formulation design for targeted therapeutic uses. </p>.

Enhancing Nanobody Immunoassays through Ferritin Fusion: Construction of a Salmonella-Specific Fenobody for Improved Avidity and Sensitivity.

Nanobodies (Nbs) serve as powerful tools in immunoassays. However, their small size and monovalent properties pose challenges for practical application. Multimerization emerges as a significant strategy to address these limitations, enhancing the utilization of nanobodies in immunoassays. Herein, we report the construction of a Salmonella-specific fenobody (Fb) through the fusion of a nanobody to ferritin, resulting in a self-assembled 24-valent nanocage-like structure. The fenobody exhibits a 35-fold increase in avidity compared to the conventional nanobody while retaining good thermostability and specificity. Leveraging this advancement, three ELISA modes were designed using Fb as the capture antibody, along with unmodified Nb422 (FbNb-ELISA), biotinylated Nb422 (FbBio-ELISA), and phage-displayed Nb422 (FbP-ELISA) as the detection antibody, respectively. Notably, the FbNb-ELISA demonstrates a detection limit (LOD) of 3.56 × 104 CFU/mL, which is 16-fold lower than that of FbBio-ELISA and similar to FbP-ELISA. Moreover, a fenobody and nanobody sandwich chemiluminescent enzyme immunoassay (FbNb-CLISA) was developed by replacing the TMB chromogenic substrate with luminal, resulting in a 12-fold reduction in the LOD. Overall, the ferritin-displayed technology represents a promising methodology for enhancing the detection performance of nanobody-based sandwich ELISAs, thereby expanding the applicability of Nbs in food detection and other fields requiring multivalent modification.

Cationic surfactant-assisted foam fractionation enhances the removal of short-chain perfluoroalkyl substances from impacted water

Several studies have demonstrated that air-bubbling and foam fractionation techniques can efficiently remove long-chain PFAS from contaminated water. However, removing short-chain PFAS is challenging due to its lower surface activity and inability to form self-assembly structures at the air-water interface. In this study, we tested various additives, including salts, surfactants, and polymers, to improve short-chain PFAS (e.g., perfluorobutanesulfonic acid (PFBS) and perfluorobutanoic acid (PFBA)) removal in non-foaming solutions using a bench-scale system. We found that in the presence of cetyltrimethylammonium chloride (CTAC) and salt, air-bubbling can significantly remove 0.5 μg L−1 of PFBS and PFBA in deionized water by >99% (15 min) and 81% (60 min), respectively. The decline of surface tension and the formation of thin foam-like layers during bubbling, controlled by the concentration of CTAC, significantly improved the removal of short-chain PFAS. Adding anionic and neutral surfactants showed no removal of short-chain PFAS during bubbling, suggesting the importance of the electrostatic interactions between short-chain PFAS and the cationic CTAC. We observed a 1:1 M ratio between CTAC and PFBS removed from the solution, suggesting the formation of ion pairs in the solution and enhancing the surface activity of the overall neutral (PFAS-CTAC) complex. A mass balance of the system revealed that the primary mechanism by which PFAS was removed from non-foaming waters was through aerosol generation (70−100%). Using the optimized condition, PFAS mixtures (short- and long-chain PFAS, including five recently regulated PFAS by USPEA, 2 nM each) in deionized water and natural groundwater were successfully removed to below detection (>99% removal; <2 ng L−1), except for PFBA (25−73% removal). These results provide an improved understanding of the mechanism by which PFAS is removed during foam fractionation and highlight the need for capturing aerosols enriched with PFAS to prevent secondary contamination.

Switchable Dual Circularly Polarized Luminescence in Through-Space Conjugated Chiral Foldamers.

Organic materials with switchable dual circularly polarized luminescence (CPL) are highly desired because they can not only directly radiate tunable circularly polarized light themselves but also induce CPL for guests by providing a chiral environment in self-assembled structures or serving as the hosts for energy transfer systems. However, most organic molecules only exhibit single CPL and it remains challenging to develop organic molecules with dual CPL. Herein, novel through-space conjugated chiral foldamers are constructed by attaching two biphenyl arms to the 9,10-positions of phenanthrene, and switchable dual CPL with opposite signs at different emission wavelengths are successfully realized in the foldamers containing high-polarizability substitutes (cyano, methylthiol and methylsulfonyl). The combined experimental and computational results demonstrate that the intramolecular through-space conjugation has significant contributions to stabilizing the folded conformations. Upon photoexcitation in high-polar solvents, strong interactions between the biphenyl arms substituted with cyano, methylthio or methylsulfonyl and the polar environment induce conformation transformation for the foldamers, resulting in two transformable secondary structures of opposite chirality, accounting for the dual CPL with opposite signs. These findings highlight the important influence of the secondary structures on the chiroptical property of the foldamers and pave a new avenue towards efficient and tunable dual CPL materials.

Liquid crystal gelators based on tetrathiafulvalene supramolecular assemblies: Synthesis, characterization and potential application

We synthesized a series of novel liquid crystal (LC) gelators by attaching two cholesterol groups through two ω-thioalkanoyloxy spacers of varying length to thia-crown-annulated tetrathiafulvalene (TTF) moieties (1a–e). Among these compounds, 1b and 1d underwent gelation to form stable supramolecular gels in various organic solvents, and their self-assembled morphology and structure indicated that Van der Waals interactions were the driving force of gel formation. In addition, more than half of the gels (1a–d) transformed into nematic LCs in a certain temperature range, while gelators that did not crystallize during cooling from the isotropic melt formed glassy mesogens. Notably, gelators obtained from n-hexane readily adsorbed rhodamine B in solution, which was considered useful for removing toxic dye molecules in wastewater. LC molecules described herein were capable of gelation and have useful oxidation and stimulus-responsive properties. They may therefore be useful for developing sensors and optoelectronic materials.

Rationale Design for Anchoring Pendant Groups of Zwitterionic Polymeric Medical Coatings.

A biocompatible and antifouling polymeric medical coating was developed through rational design for anchoring pendant groups for the modification of stainless steel. Zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) was copolymerized individually with three anchoring monomers of carboxyl acrylamides with different alkyl spacers, including acryloylglycine (2-AE), 6-acrylamidohexanoic acid (6-AH), and 11-acrylamidoundecanoic acid (11-AU). The carboxylic acid groups are responsible for the stable grafting of copolymers onto stainless steel via a coordinative interaction with metal oxides. Due to hydrophobic interaction and hydrogen bonding, the anchoring monomers enable the formation of self-assembling structures in solution and at a metallic interface, which can play an important role in the thin film formation and functionality of the coatings. Therefore, surface characterizations of anchoring monomers on stainless steel were conducted to analyze the packing density and strength of the intermolecular hydrogen bonds. The corresponding copolymers were synthesized, and their aggregate structures were assessed, showing micelle aggregation for copolymers with higher hydrophobic compositions. The synergistic effects of inter/intramolecular interactions and hydrophobicity of the anchoring monomers result in the diversity of the thickness, surface coverage, wettability, and friction of the polymeric coatings on stainless steel. More importantly, the antifouling properties of the coatings against bacteria and proteins were strongly correlated to thin film formation. Ultimately, the key lies in deciphering the molecular structure of the anchoring pendants in thin film formation and assessing the effectiveness of the coatings, which led to the development of medical coatings through the graft-onto approach.

Characterize and Mediate Assembly of Triptycenes on Au(111) Surface.

Herein, we report the assembly behavior of triptycenes with aldehyde (Trip-1) and amino (Trip-2) groups on pristine and iodine-passivated Au(111) surfaces by a combination of scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and density functional theory (DFT) calculation. On Au(111) surface, Trip-1 forms long trimer chains and two-dimensional islands via aldehyde-aldehyde hydrogen bonding in one dimension and π-π stacking of adjacent benzene rings in the other dimension. In contrast, Trip-2 lies as individuals or in disorderly stacked islands. Trip-2 and Trip-1 can be mixed in an arbitrary ratio. And Trip-2 molecules disrupt the ordered self-assembly structure of Trip-1 due to the formation of stronger aldehyde-amino hydrogen bonding. DFT, XPS, and Raman spectra confirm the conformational difference of Trip-1 and -2, as well as the aldehyde-amino hydrogen bonding formation in Trip-1 and Trip-2 mixture. On the iodine-passivated Au(111) surface, Trip-1 forms single-molecule chains and a hexagonal closely packed structure due to iodine interlayer mediation. Trip-2 molecules disrupt the hexagonal closely packed structure of Trip-1.

Regulation effects on naphthalimide self-assembly system by terminal pyridine isomers and the coordination of metal ions

Three novel naphthalimide-based gelators (NAPP, NAMP and NAOP) linked three different amines: 4-(aminomethyl)pyridine, 3-(aminomethyl)pyridine, or 2-(aminomethyl)pyridine were designed and synthesized. NAPP, NAMP and NAOP could self-assemble into fluorescent gels in some solvents and formed a variety of morphologies. The self-assembly behaviors of three gelators in DMSO/H2O (10/1, v/v) were characterized by UV–vis absorption, fluorescence, Fourier transform infrared (FTIR), X-ray diffractions (XRD) and water contact angle experiment, and the effect of different N sites in pyridine in this self-assembly system was investigated. On the base of coordination ability of pyridine groups to metal ions, the self-assembly process could be regulated by the addition of metal ions. NAPP, NAMP and NAOP solutions had highly selective and ultrafast fluorescence detection capabilities for Fe3+ with a low limit of detection. The self-assembly structure and surface wettability of the gel self-assembly system could be adjusted by adding metal ions. The hydrophobic surface of xerogels NAPP and NAMP is transformed into a hydrophilic surface at the present of Fe3+. And the hydrophilic and hydrophobic surfaces of NAPP and NAMP could realize the transformation of hydrophilic and hydrophobic surfaces by the coordination of metal ions. This study provided a way for regulating the self-assembly process by the distance between the N site on pyridine and the amide segment and metal coordination.