Molecular Component Structures MediatedFormation of Self-assemblies

Molecular recognition directed self-assemblies from complementary molecular components, melamine and barbituric acid derivatives were studied by means of NMR, fluorescence, and TEM. It was found that both the process of the self-assembly and the morphologies of the result- ed self-assemblies could be mediated by modifying the structures of the molecular components used. The effect of the structures of the molecular components on the formation of the self-as- semblies was discussed in terms of intermolecular interactions.

A nitric oxide-triggered hydrolysis reaction to construct controlled self-assemblies with complex topologies

Hydrolysis reactions are capable of directing the non-equilibrium assembly of biomolecular scaffolds to realize sophisticated structures and functions in natural systems.However,utilizing the proper hydrolysis reactions to construct controlled assemblies with complex topologies is still an arduous challenge in artificial systems and needs to be addressed.Herein,we report a nitric oxide(NO)-triggered slow hydrolysis strategy for the controlled construction of biomimetic supramolecular toroids(STs),thus realizing their visualization of intermediate structures and regulation of geometry parameters.This presented protocol harnesses hydrolysis reactions to control of non-equilibrium self-assembly processes for the construction of self-assemblies with complex topologies successfully,which sheds light on how the hydrolysis reaction rate can modulate the kinetic pathway of assembly,thus realizing the artificial establishment of bio-inspired hierarchical structures.

Pillar[6]arene-based supramolecular self-assemblies for twopronged GSH-consumption-augmented chemo/photothermal therapy

The abundant intracellular glutathione(GSH)in cancer cells severely undermines the therapeutic efficacy of different treatments due to their role in protecting cancer cells from the associated oxidative stress.Developing a highly integrated system to consume GSH would help to improve the therapeutic outcomes.In this study,supramolecular prodrug self-assemblies(SPSAs)with IR825 loaded inside were developed to consume GSH via two-pronged pathways while augmenting the therapeutic potency of chemo/photothermal treatment.SPSAs were prepared using water-soluble pillar[6]arene(WP[6])as host units and H_(2)O_(2)-responsive nitrogen mustard prodrug,chlorambucil-(phenylboronic acid pinacol ester)conjugates(Cb-BE),as the guests.When SPSAs were internalized by cancer cells,the generation of quinone methide(QM)from Cb-BE and singlet oxygen(^(1)O_(2))from irradiation-activated IR825 could consume GSH in a concerted way.As such,the therapeutic efficacies of the released chlorambucil and the accompanied hyperthermia were augmented toward synergistically inhibiting tumor growth.

Nanostructured self-assemblies of photosensitive dyes: green and efficient theranostic approaches

Recently,nano theranostics,by integrating diagnostic and therapeutic functions into a nano system,have provided increasing opportunities for the design of personalized medicine in cancer.Among the construction method of various theranostic nano systems,the design of single component nanoparticles which are composed of organic photosensitive dyes has become a promising approach to constructing multifunctional nano-theranostic systems,thanks to its unique advantages such as defined structure,100%loading,and high repeatability.Specifically,depending on the inherent photonic imaging and therapeutic properties of the photosensitive dyes,the multifunctional purpose which integrates theranostic effects and targeting abilities can be realized via reasonable molecular modification and supramolecular assembly.In this review,recent advances in the development of nanostructured self-assemblies of porphyrins,phthalocyanines,and boron-dipyrromethanes for theranostics are summarized.Emphasis on their design consideration and theranostic applications are presented.Additionally,prospects for clinical practice and potential challenges of this rapidly growing field are also provided.

Time-resolved luminescent nanoprobes based on lanthanide nucleotide self-assemblies for alkaline phosphatase detection

Currently,enzyme-responsive nanomaterials have shown great promise in prognosis or diagnosis of disease biomarker.However,the great obstacle for conventional enzyme-responsive nanomaterials frequently lies in autofluorescence interference,poor monodispersity,uncontrollable size and morphology,low optical stability,and biotoxicity,which fundamentally impede their practical application in biological systems.To overcome these deficiencies,we proposed a novel strategy for reliable and precise detection of an enzyme disease biomarker,alkaline phosphatase(ALP),through lanthanide(Ln^(3+))nucleotide nanoparticles(LNNPs)with extremely improved monodispersity and uniformity,which were achieved by the coordination self-assembly between ATP and Ln^(3+)inside micellar nanoreactor.Specifically,for ATP-Ce/Tb LNNPs,highly improved photoluminescence(PL)emission of Tb^(3+)can be achieved via efficient Ce^(3+)sensitization.We demonstrated that ALP could specifically cleave the phosphorus–oxygen(P–O)bonds of ATP and result in the collapse of ATP-Ce/Tb scaffold,finally leading to the PL quenching of Tb^(3+).By taking advantage of time-resolved(TR)PL technique,the fabricated ATP-Ce/Tb LNNPs presented superior selectivity and sensitivity for the ALP bioassay in complicated serum samples,thus revealing the great potential of ATP-Ce/Tb LNNPs in the areas of ALP-related disease prognosis and diagnosis.

Alcohol solvent effect on the self-assembly behaviors of lignin oligomers

The interactions between lignin oligomers and solvents determine the behaviors of lignin oligomers self-assembling into uniform lignin nanoparticles(LNPs).Herein,several alcohol solvents,which readily interact with the lignin oligomers,were adopted to study their effects during solvent shifting process for LNPs’production.The lignin oligomers with widely distributed molecular weight and abundant guaiacyl units were extracted from wood waste(mainly consists of pine wood),exerting outstanding self-assembly capability.Uniform and spherical LNPs were generated in H_(2)O-n-propanol cosolvent,whereas irregular LNPs were obtained in H_(2)O-methanol cosolvent.The unsatisfactory self-assembly performance of the lignin oligomers in H_(2)O-methanol cosolvent could be attributed to two aspects.On one hand,for the initial dissolution state,the distinguishing Hansen solubility parameter and polarity between methanol solvent and lignin oligomers resulted in the poor dispersion of the lignin oligomers.On the other hand,strong hydrogen bonds between methanol solvent and lignin oligomers during solvent shifting process,hindered the interactions among the lignin oligomers for self-assembly.

Self-assembly of perovskite nanocrystals:From driving forces to applications

Self-assembly of metal halide perovskite nanocrystals(NCs)into superlattices can exhibit unique collective properties,which have significant application values in the display,detector,and solar cell field.This review discusses the driving forces behind the self-assembly process of perovskite NCs,and the commonly used self-assembly methods and different self-assembly structures are detailed.Subsequently,we summarize the collective optoelectronic properties and application areas of perovskite superlattice structures.Finally,we conclude with an outlook on the potential issues and future challenges in developing perovskite NCs.

Factors resisting protein adsorption on hydrophilic/hydrophobic self-assembled monolayers terminated with hydrophilic hydroxyl groups

The hydroxyl-terminated self-assembled monolayer(OH-SAM),as a surface resistant to protein adsorption,exhibits substantial potential in applications such as ship navigation and medical implants,and the appropriate strategies for designing anti-fouling surfaces are crucial.Here,we employ molecular dynamics simulations and alchemical free energy calculations to systematically analyze the factors influencing resistance to protein adsorption on the SAMs terminated with single or double OH groups at three packing densities(∑=2.0 nm^(-2),4.5 nm^(-2),and 6.5 nm^(-2)),respectively.For the first time,we observed that the compactness and order of interfacial water enhance its physical barrier effect,subsequently enhancing the resistance of SAM to protein adsorption.Notably,the spatial hindrance effect of SAM leads to the embedding of protein into SAM,resulting in a lack of resistance of SAM towards protein.Furthermore,the number of hydroxyl groups per unit area of double OH-terminated SAM at ∑=6.5 nm^(-2) is approximately 2 to 3 times that of single OH-terminated SAM at ∑=6.5 nm^(-2) and 4.5 nm^(-2),consequently yielding a weaker resistance of double OH-terminated SAM towards protein.Meanwhile,due to the structure of SAM itself,i.e.,the formation of a nearly perfect ice-like hydrogen bond structure,the SAM exhibits the weakest resistance towards protein.This study will complement and improve the mechanism of OH-SAM resistance to protein adsorption,especially the traditional barrier effect of interfacial water.

Layer by Layer Self-assembly Fiber-based Flexible Electrochemical Transistor

Poly(3,4-ethylenedioxyethiophene)-polystyrene sulfonic acid(PEDOT:PSS)/polyallyl dimethyl ammonium chloride modified reduced graphene oxide(PDDA-rGO)was layer by layer self-assembled on the cotton fiber.The surface morphology and electric property was investigated.The results confirmed the dense membrane of PEDOT:PSS and the lamellar structure of PDDA-rGO on the fibers.It has excellent electrical conductivity and mechanical properties.The fiber based electrochemical transistor(FECTs)prepared by the composite conductive fiber has a maximum output current of 8.7 mA,a transconductance peak of 10 mS,an on time of 1.37 s,an off time of 1.6 s and excellent switching stability.Most importantly,the devices by layer by layer self-assembly technology opens a path for the true integration of organic electronics with traditional textile technologies and materials,laying the foundation for their later widespread application.

Chitosan/Sodium Alginate Multilayer pH-Sensitive Films Based on Layer-by-Layer Self-Assembly for Intelligent Packaging

The abuse of plastic food packaging has brought about severe white pollution issues around the world.Developing green and sustainable biomass packaging is an effective way to solve this problem.Hence,a chitosan/sodium alginate-based multilayer film is fabricated via a layer-by-layer(LBL)self-assembly method.With the help of superior interaction between the layers,the multilayer film possesses excellent mechanical properties(with a tensile strength of 50 MPa).Besides,the film displays outstanding water retention property(blocking moisture of 97.56%)and ultraviolet blocking property.Anthocyanin is introduced into the film to detect the food quality since it is one natural plant polyphenol that is sensitive to the pH changes ranging from 1 to 13 in food when spoilage occurs.It is noted that the film is also bacteriostatic which is desired for food packaging.This study describes a simple technique for the development of advanced multifunctional and fully biodegradable food packaging film and it is a sustainable alternative to plastic packaging.

Morphological Evolution of Self-Assembled Sodium Dodecyl Sulfate/Dodecyltrimethylammonium Bromide@Epoxy-β-Cyclodextrin Supramolecular Aggregates Induced by Temperature

Bio-based cyclodextrins(CDs)are a common research object in supramolecular chemistry.The special cavity structure of CDs can form supramolecular self-assemblies such as vesicles and microcrystals through weak interaction with guest molecules.The different forms of supramolecular self-assemblies can be transformed into each other under certain conditions.The regulation of supramolecular self-assembly is not only helpful to understand the self-assembly principle,but also beneficial to its application.In the present study,the self-assembly behavior of epoxy-β-cyclodextrin(EP-β-CD)and mixed anionic and cationic surfactant system(sodium dodecyl sulfate/dodecyltrimethylammonium bromide,SDS/DTAB)in aqueous solution was studied.Morphological and particle size characterization found that the SDS/DTAB@EP-β-CD complex,as the basic building unit,self-assembled into worm-like micelles at lower temperatures and vesicles at higher temperatures.Nuclear magnetic resonance(NMR)and Fourier transform infrared spectroscopy(FT-IR)analysis revealed that the driving force for the formation of vesicles and worm-like micelles was the hydrogen bonds between EP-β-CD molecules,while water molecules played an important role in promoting vesicle formation between SDS/DTAB@EP-β-CD units.Herein,the mechanism of the morphologic transformation of SDS/DTAB@EP-β-CD supramolecular aggregates induced by temperature was elucidated by exploring the self-assembly process,which may provide an excellent basis for the development of delivery carriers.

Development of polyvinylpyrrolidone/paclitaxel self-assemblies for breast cancer

The goal of this investigation was to develop and demonstrate a polymer/paclitaxel selfassembly(PTX-SA) formulation. Polymer/PTX-SAs were screened based on smaller size of formulation using dynamic light scattering analysis. Additionally, fluorescence microscopy and flow cytometry studies exhibited that polyvinylpyrrolidone(PVP)-based PTX-SAs(PVP/PTX-SAs) had superior cellular internalization capability in MCF7 and MDA-MB-231 breast cancer cells. The optimized PVP/PTXSAs exhibited less toxicity to human red blood cells indicating a suitable formulation for reducing systemic toxicity. The formation of PVP and PTX self-assemblies was confirmed using fluorescence quenching and transmission electron microscopy which indicated that the PVP/PTX-SAs were spherical in shape with an average size range of 53.81 nm as detected by transmission electron microscopy(TEM).FTIR spectral analysis demonstrates incorporation of polymer and paclitaxel functional groups in PVP/PTX-SAs. Both proliferation(MTS) and clonogenic(colony formation) assays were used to validate superior anticancer activity of PVP/PTX-SAs in breast cancer cells over paclitaxel. Such superior anticancer activity was also demonstrated by downregulation of the expression of pro-survival protein(Bcl-x L), upregulation of apoptosis-associated proteins(Bid, Bax, cleaved caspase 7, and cleaved PARP)and β-tubulin stabilization. These results support the hypothesis that PVP/PTX-SAs improved paclitaxel delivery to cancer cells.

The self-assemblies of a newly designed star-shaped molecule end-capped with bromine atoms studied by scanning tunneling microscopy

A new star-shaped molecule StOF-Br_3 containing oligofluorenes and halogen atoms(Bromine) has been synthesized and studied by Scanning Tunneling Microscopy(STM) at the highly oriented pyrolytic graphite(HOPG) surface.We have obtained the high-resolution self-assembled STM images,from which the highly ordered and closely packed non-porous arrangements of the StOF-Br_3 molecular selfassemblies at the heptanoic acid/HOPG surface could be observed.The molecular models and selfassembled StOF-Br_3 architectures have been given in the following text.Besides,we have also figured out the surface free energy by the density functional theory(DFT) calculation,which proved that the halogen...halogen interaction was strong enough to stabilize the ordered molecular self-assemblies.This work verifies the existence of bromine...bromine interactions,and meanwhile provides a kind of effective approach for quickly building ordered molecular nanoarchitectures with large areas and different geometries.

Modulating the Helicity of Sugar-Substituted Perylene Diimide Self-assemblies by Solvent Polarilities

Modulating the helicity of self-assemblies of conjugated molecules is important for their application in chiral electronics.In this communication,solvent effect has been investigated on how to modulate the helicity of supramolecular assemblies of sugar-substituted perylenediimide(PTCDI-BAG)by using UV-Vis,circular dichroism spectroscopy and transmission electron microscopy.Left-handed helical nanowires are obtained in the mixed solvent system of both N,N-dimethylformamide/ethanol(DMF/ethanol)and N,N-dimethylacetamide/ethanol(DMAC/ethanol).As changing the solvents into dimethyl sulfoxide/ethanol(DMSO/ethanol),ethylene glycol/ethanol(EG/ethanol),or N-methyl-2-pyrrolidone/ethanol(NMP/ethanol),only right-handed heical nanowires are observed.The chirality of supramolecular structures can be tuned by the controlling of the polarity of the solvents.A theoretical calculation is carried out to explain the chiral optical inversion phenomena of PTCDI-BAG aggregates in different solvents,which reveals that reversed CD spectra is due to the difference of clockwise and anticlockwise rotation of the dimer.

Bio-inspired chiral self-assemblies promoted neuronal differentiation of retinal progenitor cells through activation of metabolic pathway

Retinal degeneration is a main class of ocular diseases.So far,retinal progenitor cell(RPC)transplantation has been the most potential therapy for it,in which promoting RPCs neuronal differentiation remains an unmet challenge.To address this issue,innovatively designed L/D-phenylalanine based chiral nanofibers(LPG and DPG)are employed and it finds that chirality of fibers can efficiently regulate RPCs differentiation.qPCR,western blot,and immunofluorescence analysis show that right-handed helical DPG nanofibers significantly promote RPCs neuronal differentiation,whereas left-handed LPG nanofibers decrease this effect.These effects are mainly ascribed to the stereoselective interaction between chiral helical nanofibers and retinol-binding protein 4(RBP4,a key protein in the retinoic acid(RA)metabolic pathway).The findings of chirality-dependent neuronal differentiation provide new strategies for treatment of neurodegenerative diseases via optimizing differentiation of transplanted stem cells on chiral nanofibers.

Combination therapy to overcome ferroptosis resistance by biomimetic self-assembly nano-prodrug

Ferroptosis has emerged as a potent form of no-apoptotic cell death that offers a promising alternative to avoid the chemoresistance of apoptotic pathways and serves as a vulnerability of cancer.Herein,we have constructed a biomimetic self-assembly nano-prodrug system that enables the co-delivery of gefitinib(Gefi),ferrocene(Fc)and dihydroartemisinin(DHA)for the combined therapy of both ferroptosis and apoptosis.In the tumor microenvironment,this nano-prodrug is able to disassemble and trigger drug release under high levels of GSH.Interestingly,the released DHA can downregulate GPX4 level for the enhancement of intracellular ferroptosis from Fc,further executing tumor cell death with concomitant chemotherapy by Gefi.More importantly,this nano-prodrug provides highly homologous targeting ability by coating related cell membranes and exhibits outstanding inhibition of tumor growth and metastasis,as well as no noticeable side-effects during treatments.This simple small molecular self-assembled nano-prodrug provides a new reasonably designed modality for ferroptosis-combined chemotherapy.

Self-assemblies of TTF derivatives with fluorinated phenyls and pyridine group

The self-assembly characteristics of tetrathiafulvalene(TTF) derivatives molecules 1-3 at the 1-phenyloctane/HOPG(HOPG = highly oriented pyrolytic graphite) interface had been carefully studied by scanning tunneling microscopy(STM) method. The number of F atoms on the phenyl group had significantly affected the self-assembly structures. High-resolution STM images make clear the different assembly structures between the molecules 1-3, which attribute to the different F atom numbers and pyridine group in the molecule. Density functional theory(DFT) calculations have been performed to reveal the formation mechanism.

Pinning-down molecules in their self-assemblies with multiple weak hydrogen bonds of C-H···F and C-H···N

Two-dimensional self-assemblies of four partially fluorinated molecules, 1,4-bis（2,6-difluoropyridin-4-yl）benzene, 4,4＇-bis（2,6-difluoropyridin-4-yl）-1,1＇-biphenyl, 4,4＇-bis（2,6-difluoropyridin-4-yl）-1,1＇：4＇,1＇-terphenyl and 4,4＇-bis（2,6-difluoropyridin-3-yl）-1,1＇-biphenyl, involving weak intermolecular C-H···F and C-H···N hydrogen bonds were systematically investigated on Au（111） with low-temperature scanning tunneling microscopy. The inter-molecular connecting modes and binding sites were closely related to the backbones of the building blocks, i.e., the molecule length determines its binding sites with neighboring molecules in the assemblies while the attaching positions of the N and F atoms dictate its approaching and docking angles. The experimental results demonstrate that multiple weak hydrogen bonds such as C-H···F and C-H···N can be efficiently applied to tune the molecular orientations and the self-assembly structures accordingly.

Active straining engineering on self-assembled stacked Ni-based hybrid electrode for ultra-low overpotential

Generating sufficient strains on metal surfaces are highly challenging owing to that most metals can deform plastically to relax the strains on the surfaces.In this work,we developed a facile but highly efficient stacked deposition strategy to in situ activation and reconstruction of NiO/NiOOH on Ni matrix,following with the migration of Fe ions to NiOOH.The Fe sites on the Ni/NiO/NiOOH facilitate the formation of the stable*OH oxygenated intermediates,and the Ni matrix in the catalyst provides the catalyst excellent stability.The oxygen evolution reaction(OER)performance of the stacked NiFe-5 with compressive strain displays the strengthened binding to oxygenated intermediates and superior OER activity,the ultralow overpotentials of 162 versus reversible hydrogen electrode at 10 mA cm^(-2).On the other hand,the Ni-5 without the incorporation of Fe has shown an outstanding hydrogen evolution reaction(HER)activity,affording an overpotential of 47 mV at 10 mA cm^(-2).The NiFe-5‖Ni-5 enables the overall water splitting at a voltage of 1.508 V to achieve 20 mA cm^(-2) with remarkable durability.The stacked deposition strategy improves binding strength of Ni-based catalysts to oxygenated intermediates via generating compressive strain,causing high catalytic activities on OER and HER.

Au@Ag Core-shell Nanorods Self-assembled on Polyelectrolyte Multilayers for Ultra-High Sensitivity SERS Fiber Probes

We demonstrated a chemical process in the fabrication of a SERS fiber probe with an ultrahigh sensitivity.The synthesis was carried out by preparing Au@Ag core-shell nanorods (Au@Ag-NRs) selfassembled on polyelectrolyte (PE) multilayers,for which Au@Ag-NRs were controlled by adjusting the silver layer thickness.The effect of silver layer thickness of Au@Ag-NRs on the SERS performance of the fiber probe was investigated.The SERS fiber probe shows the best performance when the silver layer thickness is controlled at 8.57 nm.Under the condition of optimizing silver layer thickness,the fiber probe exhibits ultra-high sensitivity (i e,10^(-10) M crystalline violet,CV),good reproducibility (i e,RSD of 3.5%) and stability.Besides,electromagnetic field distribution of the SERS fiber probe was also investigated.The strongest enhancement is found within the core of fiber,whereas a weakened electromagnetic field exists in the fiber cladding layer.The SERS fiber probe can be a good candidate in ultra-trace detection for biomedical and environmental areas.