Efficient Self-assembly Research Articles

Tailoring the Tag/Catcher System by Integrating Covalent Bonds and Noncovalent Interactions for Highly Efficient Protein Self-Assembly

Covalent bonds and noncovalent interactions play crucial roles in enzyme self-assembly. Here, we designed a Tag/Catcher system named NGTag/NGCatcher in which the Catcher is a highly charged protein that can bind proteins with positively charged tails and rapidly form a stable isopeptide bond with NGTag. In this study, we present a multienzyme strategy based on covalent bonds and noncovalent interactions. In vitro, mCherry, YFP, and GFP can form protein-rich three-dimensional networks based on NGCatcher, NGTag, and RK (Arginine/Lysine) tails, respectively. Furthermore, this technology was applied to improve lycopene production in Escherichia coli. Three key enzymes were involved in lycopene production variants from Deinococcus wulumuqiensis R12 of NGCatcher_CrtE, NGTag_Idi, and RKIspARK, where the multienzyme complexes were clearly observed in vivo and in vitro, and the lycopene production in vivo was 17.8-fold higher than that in the control group. The NGTag/NGCatcher system will provide new opportunities for in vivo and in vitro multienzyme catalysis.

Efficient formation of ZIF-8 promoted by DBU for the preparation of ZnO and Ce/ZnO nanomaterials

In this work, the efficient preparation of zeolitic imidazolate framework-8 (ZIF-8) from Zn2+ and 2-methylimidazole (2-MI) promoted by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was presented. The mechanism obtained from NMR, MS, DFT calculations, and conductivity shows that [DBUH][2-MI] ionic liquid formed in-situ from proton transfer between DBU and 2-MI can ionize 2-MI to [2-MI]- and form electrostatic interaction between Zn2+ and [2-MI]-, resulting in the efficient self-assembly of Zn2+ and 2-MI to form ZIF-8. Moreover, the effect of the amount of DBU on ZIF-8 indicates that too much DBU will cause excessive deprotonation of 2-MI, leading to agglomerate of ZIF-8. Accordingly, the optimal ratio to form ZIF-8 is n(DBU): n(2-MI): n(Zn2+) = 2: 25: 1.25, which is also employed to prepare cerium-containing ZIF-8. Moreover, ZnO and Ce/ZnO nanomaterials are prepared by using ZIF-8 and cerium-containing ZIF-8 as precursors respectively, and their structure and morphology are characterized by XRD, FT-IR, SEM, and TEM. Interestingly, Ce content in Ce/ZnO obtained by EDS spectrum is basically consistent with the actual doping amount, indicating that DBU can effectively control the doping of Ce in ZIF-8. Finally, the photocatalytic degradation ability of ZnO and Ce/ZnO for Rhodamine B under visible light and sunlight is investigated in detail.

Efficient Synthesis and Self-Assembly of Segmented Hyperbranched Block Copolymers via RAFT-Mediated Dispersion Polymerization Using Segmented Hyperbranched Macro-RAFT Agents

Efficient Synthesis and Self-Assembly of Segmented Hyperbranched Block Copolymers via RAFT-Mediated Dispersion Polymerization Using Segmented Hyperbranched Macro-RAFT Agents

A novel pH-responsive charge reversal nanospheres based on acetylated histidine-modified lignin for drug delivery

In this work, we developed a novel technique to prepare pH-responsive charge reversal nanospheres based on softwood kraft lignin (SKL) through two steps modification and high efficient self-assembly. SKL was first grafted with imidazole groups by Mannich reaction and further fabricated into acetylated histidine-modified lignin (Ace-SKL-HIS) via acetylation reaction. Ace-SKL-HIS nanospheres (Ace-SKL-HIS NPs) were prepared by fast vacuum evaporation method, their effective diameters (ED) were around 100 nm, exhibited low Polydispersity Index(PDI, <0.2) and good shape. Ace-SKL-HIS NPs demostrated excellent pH response performance with charge reversal under acidic environment. Then, curcumin was applied as a model drug to prepare drug-loaded nanospheres (Ace-SKL-HIS@CUR). The drug loading degree (DL%) and encapsulation efficiency (EE%) were 22.34 % and 70.76 %, respectively. The in vitro release behavior of curcumin exhibited excellent pH dependent release property, 76.82 % release at pH 5.7 while only 12.92 % at pH 7.4 in 120 h. Furthermore, in vitro cytotoxicity studies showed that Ace-SKL-HIS@CUR had potent anti-tumor effect, with IC50 of 28.16 μg/ mL. This study constructed a promising nanocarrier platform for cancer drug delivery, which paved a new way to the high value-added application of lignin.

Polypyrrole/SnCl2 modified bacterial cellulose electrodes with high areal capacitance for flexible supercapacitors

Polypyrrole (PPy)/bacterial cellulose (BC) composite membranes are a promising kind of lightweight and flexible electrodes for supercapacitors. Herein, we explored a facile and efficient electrostatic self-assembly approach to uniformly depositing anion-doped PPy onto positively charged SnCl2-modifed BC (SBC). The obtained PPy@SBC electrode exhibited a high areal capacitance of 5718 mF cm−2 at a current density of 0.5 mA cm−2, a desirable capacitance retention of 83.1% at 5.0 mA cm−2 and excellent cycling stability (a capacitance retention of 86.8% after 10,000 cycles at 10 mA cm−2). A symmetric flexible supercapacitor was further assembled with the PPy@SBC electrodes, which delivered outstanding mechanical flexibility with negligible capacitance decay under different bent states. This study shows impressive potential in fabricating high-performance electrodes for flexible supercapacitors.

Photoluminescent polymer cubosomes prepared by RAFT-mediated polymerization-induced self-assembly

The preparation of photoluminescent polymer assemblies with a wide range of morphologies, including spongosomes and cubosomes, via an efficient RAFT-mediated polymerization-induced self-assembly (RAFT-PISA) process, was demonstrated.

Flexible and durable poly para-phenylene terephthalamide fabric constructed by polydopamine and corrugated Co-Ni-P alloy with reflection characteristic for electromagnetic interference shielding

Aerospace, military and precision electronic equipment urgently need efficient, lightweight and durable flexible electromagnetic interference (EMI) shielding fabrics to shield electromagnetic radiation. Inspired by mussels, the corrugated PPTA@PDA@CoNiP composite material with multi-reflection interfaces was designed on the surface of poly para-phenylene terephthalamide (PPTA) fabric through efficient self-assembly of polydopamine (PDA) and electroless deposition Co-Ni-P. The ferromagnetic Co-Ni-P formed a strong interface adhesion with the fabric, and constructed a closed magnetic conductive network (saturation magnetization of 50.8 emu/g and resistance value around 150 mΩ), which enabled electromagnetic radiation to be reflected and absorbed. Hence, PPTA@PDA@CoNiP fabric sample exhibited excellent electromagnetic interference shielding effectiveness (EMI SE, 76.9 dB), absorption loss (SEA, 58.7 dB) and reflection loss (SER, 18.2 dB) through the synergistic effect of electrical loss and magnetic loss in X-band. PPTA@PDA@CoNiP fabric retained good electrical conductivity even after repeated bending for 1000 cycles. In addition, the fabric still had certain air permeability after deposition of Co-Ni-P, and the Co-Ni-P layer showed excellent corrosion resistance. Meanwhile, this work provided an efficient and green approach for constructing an electromagnetic shielding layer on the surface of an inert fabric.

Precise Synthesis of π-Conjugated Block Copolymers and Polymerization-Induced Chiral Self-Assembly toward Helical Nanofibers with Circularly Polarized Luminescence.

Precise synthesis and efficient self-assembly of semiconducting polymers are of great interest. Herein, we report the controlled synthesis of π-conjugated poly(phenyl isocyanide)-b-poly(phenyleneethylene) (PPI-b-PPE) copolymers via chain extension of ethynyl 4-iodobenzene initiated by Pd(II)-terminated helical poly(phenyl isocyanide) (PPI). The in-situ-generated block copolymers self-assembled into various supramolecular architectures depending on the PPE length. The helical PPI segment induced the block copolymers with an appropriate PPE length self-assemble into helical nanofibers with a controlled size and defined helicity. Interestingly, the chiral assemblies of the block copolymers exhibit intense optical activity and emit clear circularly polarized luminescence.

Anti-oxidized electrostatic self-assembly of 3D high-density Polyimide@MXene composite for superior aqueous Mg2+ storage

As a conjugated carbonyl polymer, polyimide (PI) with redox-active sites has attracted increasing research attention owing to its efficient multivalent-ion storage behaviors in low-cost and risk-free neutral aqueous electrolytes. However, the practical applications of PI remain restricted because of its low tapped density, sluggish electron transfer and structural instability. Herein, we developed a novel three-dimensional (3D) high-density PI@MXene composite through efficient electrostatic self-assembly, wherein MXene oxidation could be prevented during composite preparation. Synergistically coupling the conductive layered MXene with electro-active PI provides a 3D architecture with high tapped density (~1.12 g cm−3), enhanced electrochemical kinetics and rapid redox reaction in MgCl2 neutral aqueous electrolytes. These features can be further confirmed via Fourier transform infrared spectroscopy upon charging/discharging and density functional theory (DFT) calculations along with the highest occupied molecular orbital-lowest unoccupied molecular orbital energy gap. As an electrode, the 3D high-density PI@MXene composite exhibits remarkable aqueous Mg2+ storage (~502.2 F g−1) and superior rate and cycling performances than those of most reported polymer-based electrodes in aqueous electrolytes. As proof of concept, we fabricated a flexible Mg-ion storage device with reliable electrochemical performance and ultra-long cycling life over 20 000 cycles, stimulating its application in high-safety portable/wearable electronics.

In situ oxidation-regulated self-assembly of peptides into transformable scaffolds for cascade therapy

Reactive oxygen species (ROS) are one of important biomarkers for pathological lesions and inspire development of ROS-responsive biomaterials for disease treatment. Here we report oxidation-regulated self-assembly of peptides into transformable scaffolds by in situ ROS generation for cascade cancer therapy. While the peptide is designed by rational incorporation of methionine residues and underwent efficient oxidation-controlled self-assembly, co-assembling the peptide with its derivatives functionalized with photosensitizer or chemodrug results in the scaffolds with combinatorial therapeutic effect. Photo-induced in situ ROS generation by the photosensitizer simultaneously endows the photodynamic therapy and promotes the morphological transition due to the methionine oxidation. In vivo studies confirm the significance of in situ ROS generation for the methionine oxidation and the morphological transition of the scaffolds, which further enhance tumor accumulation and penetration of therapeutics and thereby eradicating tumor arising from a cascade therapy process. Our findings demonstrate a new and versatile strategy for ROS-associated disease treatment in the future.

Self-assembly of and optimal encoding within thin rectangles at temperature-1 in 3D

In this paper, we study the self-assembly of rectangles in a non-cooperative, 3D version of Winfree's abstract Tile Assembly Model. We prove two results. First, we give the full details for the proof of a general construction for the efficient self-assembly of thin rectangles that was first reported by Furcy, Summers and Wendlandt (2019). This construction is non-cooperative and “just-barely” 3D in the sense that it places tiles at most one step into the third dimension. Second, we give a non-cooperative, just-barely 3D optimal encoding construction that self-assembles the bits of a given binary string along the perimeter of a thin rectangle of constant height.

Hydrophobic fluorinated colloidal photonic crystals for heterogeneous aggregated cluster encoding and energy-saving applications

The construction of high-quality colloidal photonic crystals (CPCs) for optoelectronics, energy and biological applications, featuring the viable and effective self-driven assembly route, still remains a challenge. Herein, we demonstrate the efficient self-assembly of hydrophobic fluorine-containing poly(trifluoroethyl methacrylate) (PTFEMA) CPCs via hydrophobic force for heterogeneous aggregated cluster encoding and photoluminescence enhancement of liquid crystal display (LCD). The CPC films with periodic arranged structure self-assembled through the hydrophobic terminals (-CF3) display tunable brilliant structural color and large-area crack-free morphology. Moreover, taking advantage of PTFEMA emulsion and superparamagnetic Fe3O4 nanoparticle suspension as two discontinuous phases, Janus microbeads are fabricated by the triphase microfluidic technology, which are subsequently constructed into heterogeneous aggregated clusters that perform multiple structural color signals for the optical encoding. Eventually, the PTFEMA CPC film serves as the photoluminescence enhanced film to significantly elevate the photoluminescence (PL) intensity of CdSe@ZnS quantum dots by ca. 11 folds in an LCD device. The novel PTFEMA CPCs may offer the alternative opportunities for optical encoding towards sensing, anticounterfeiting and information storage, as well as the energy-saving optoelectronic devices.

An efficient electrostatic self-assembly of reduced graphene oxide-BiOI/Bi2O2CO3 p–n junction nanocomposites for enhanced visible-light photocatalytic activity

An efficient electrostatic self-assembly of reduced graphene oxide-BiOI/Bi2O2CO3 p–n junction nanocomposites for enhanced visible-light photocatalytic activity

Orthogonal Self-Assembly of a Two-Step Fluorescence-Resonance Energy Transfer System with Improved Photosensitization Efficiency and Photooxidation Activity.

During the past few decades, fabrication of multistep fluorescence-resonance energy transfer (FRET) systems has become one of the most attractive topics within supramolecular chemistry, chemical biology, and materials science. However, it is challenging to efficiently prepare multistep FRET systems with precise control of the distances between locations and the numbers of fluorophores. Herein we present the successful fabrication of a two-step FRET system bearing specific numbers of anthracene, coumarin, and BODIPY moieties at precise distances and locations through an efficient and controllable orthogonal self-assembly approach based on metal-ligand coordination and host-guest interactions. Notably, the photosensitization efficiency and photooxidation activity of the two-step FRET system gradually increased with the number of energy transfer steps. For example, the two-step FRET system exhibited 1.5-fold higher 1O2 generation efficiency and 1.2-fold higher photooxidation activity than that of its corresponding one-step FRET system. This research not only provides the first successful example of the efficient preparation of multistep FRET systems through orthogonal self-assembly involving coordination and host-guest interactions but also pushes multistep FRET systems toward the application of photosensitized oxidation of a sulfur mustard simulant.

Biodeposited Nano-CdS Drives the In Situ Growth of Highly Dispersed Sulfide Nanoparticles during Pyrolysis for Enhanced Oxygen Evolution Reaction.

A novel, efficient, and stable graphene-based composite oxygen evolution reaction (OER) catalyst, BG@Ni/Ni3S2, was designed via high-specificity, low-cost biosynthesis and efficient electrostatic self-assembly. In the synthetic process, bacterial cells containing biodeposited CdS nanocrystals, graphene oxide (GO), and Ni2+ ions are assembled into a sandwich-type hybrid precursor. The nanosized sulfur source drives in situ sulfidation during pyrolysis, which induces the uniform formation and growth of Ni/Ni3S2 composite nanoparticles (NPs) on the graphene substrate. Benefiting from the high specific surface area and uniform distribution of NPs, the catalyst has a large number of exposed active sites and exhibits rapid mass transfer. In addition, the skeleton composed of a conductive carbon matrix and metallic Ni-Ni network ensures the excellent electron transfer during the OER, and the synergistic effect of Ni0 and Ni3S2 further optimizes the electronic structure and accelerates the OER kinetics. The dominant catalytic sites at the nanointerface between Ni0 and Ni3S2 provide favorable thermodynamic conditions for the adsorption of OER intermediates. As a result, BG@Ni/Ni3S2 exhibits efficient catalytic performance for the OER: the overpotential and Tafel slope are only 320 mV at 100 mA cm-2 and 41 mV dec-1, respectively. This work provides a novel understanding of the intrinsic activity of transition metal sulfide composites and a biological-based design for OER catalysts.

Scalable and integrated flow synthesis of triple-responsive nano-motors via microfluidic Pickering emulsification

Artificial micro-/nano-motors are tiny machines as newly emerging tools capable of achieving numerous tasks. In principle, the self-phoretic motions require asymmetric structures in geometry and chemistry. However, conventional production techniques suffered from complex and time consuming multi-step process in low uniformity, and difficult to endow multi-functions into motors. This work disclosed a continuous-flow synthesis of triple-responsive (thermophoretic, chemical and magnetic movement) nano-motors (m-SiO2/Fe3O4-Pdop/Pt) via microfluidic Pickering emulsification in a process of integrated and scalable manner. The droplet microfluidic process allows efficient self-assembly of the silica nanoparticles surrounding the spherical interface of resin droplet, rendering excellent Pickering efficiency and reproducibility, and followed by anisotropic decoration of polydopamine (Pdop) and Pt catalyst in a serial flow process. The obtained Janus nanoparticles reveal double- or triple-responsive self-propulsions with synergic mobility by combining thermophoresis powered by light, catalytic driven motion in H2O2 or magnetic movement by magnet. Further, a non-metallic polydopamine based thermophoretic motion as well as an automated nano-cleaner for rapid water purification by dye removal are convincingly functioned. Finally, this novel integrated flow strategy proves a scalable manufacturing production (> 0.7 g hr−1) of the nano-motors using inexpensive single microreactor, fulfilling quantitative and qualitative needs for versatile applications.

Self-Assembly of Molecular Figure-Eight Knots Induced by Quadruple Stacking Interactions.

Molecular figure-eight knot (notation: 41) is extremely rare and presents great synthetic challenge due to its essentially complicated entanglement. To solve this synthetic problem, a quadruple stacking strategy was developed. Herein, we report the efficient self-assembly of figure-eight knots induced by quadruple stacking interactions, through the combination of four carefully selected naphthalenediimide (NDI)-based pyridyl ligands and Cp*Rh building blocks bearing large conjugated planes in a single-step strategy. Notably, slight size adjustment of the Cp*Rh units was found to affect the stability of the figure-eight knots in methanol. Additionally, reversible structural transformations between these figure-eight knots and corresponding metallorectangles could be achieved by concentration changes and solvent- and guest-induced effects. X-ray crystallographic data and NMR spectroscopy provide full confirmation of these phenomena.

Hydrophobicity-induced electrostatic interfacial self-assembly for porous silica nanospheres with tunable pore sizes and pore hierarchies

Porous materials have distinct advantages in catalysis, adsorption, and biomedicine due to their excellent loading spaces and high stability. However, the precise control on the sizes and hierarchies/distributions of pore channels in a nanoscale matrix is still challenging. Herein, a simple but efficient hydrophobicity-induced electrostatic interfacial self-assembly (HEISA) strategy is developed to synthesize porous silica nanospheres (PSNs) with large tunable pore sizes (10–30 nm) and pore hierarchies (dual-pores and tri-modal pores). In the synthesis processes, hydrophobic homopolymers polystyrene (PS) can not only act as pore-swelling agents for the enlargement of pore channels up to ∼30 nm, but also induce the evolution of pore hierarchies from dual-modal PSNs to tri-modal PSNs. By employing hydrophobic homopolymers as hydrophobicity-induced agents, a “homopolymer-mediated enlarging mesopore and creating macropore” mechanism is proposed. The degradation behaviors of PSNs in phosphate buffer saline (PBS) exhibited a pore size- and concentration-dependent manners. Furthermore, the maximum loading amount of PSNs reached 143 ± 46 mg/g of bovine serum albumin (BSA) and 258 ± 30 mg/g of catalase (CAT). More interestingly, a magnetic functionalized tri-modal PSNs with unique “vesicular” morphology was obtained by employing hydrophobic magnetite nanocrystals as hydrophobicity-induced agents via this HEISA approach, which showed an ultra-high transverse relaxivity up to 670.5 mMFe−1·S−1 in the T2-weighted magnetic resonance imaging. We therefore conceive that this proposed HEISA methodology provides a general pathway for developing ultra-large-pore mesoporous silica nanoparticles and hierarchical pore structures with various compositions and functions, further allowing the improvement of properties in biomedicine, catalysis, energy conversion and storage and adsorption or separation.

Self-assembled AIEgen nanoparticles for multiscale NIR-II vascular imaging

In the recent decades, fluorogens with aggregation-induced emission (AIEgens) have been intensively explored in biomedical applications. One main strategy to bring these hydrophobic AIEgens into the aqueous biological environment is to encapsulate them in nanoparticles with functionalized polymeric matrices. However, exploration of reliable strategies that can afford AIE nanoparticles with uniform size and stable loading efficiency with minimized variation still remains a challenge. Here, we rationally designed amphiphilic AIEgens, constructed by a hydrophobic donor-acceptor-donor (D-A-D) core and hydrophilic polyethylene glycol (PEG) chain. The afforded amphiphilic AIEgens can self-assemble into uniform nanoparticles with average sizes of ~35 nm, showing an emission maximum beyond 1000 nm and quantum yields (QYs) above 10%. We then used the bright AIE nanoparticles for multiscale intravital vascular fluorescence imaging in the second near-infrared window (NIR-II, 1000–1700 nm) in mouse and rabbit models with a high-resolution of ~38 μm and a penetration depth of ~1 cm. As such, our results demonstrate an efficient self-assembly strategy to construct advanced AIE nanoparticles for angiography.

DsDNA/ssDNA-switchable isothermal colorimetric biosensor based on a universal primer and λ exonuclease

Herein, a dsDNA/ssDNA-switchable isothermal colorimetric biosensor was established. In our design, a versatile linker domain invades into recombinase polymerase amplification (RPA) amplicons via a reverse primer with an additional linker. To activate effective amplification, a universal primer (U-P) is introduced to address the impaired efficiency in the invasion process. After billions of dsDNA amplicons with the universal linker accumulate, λ exonuclease acts as a converter and mediates the transformation from dsDNA to ssDNA for launching efficient DNA self-assembly without signal leak. The newly formed G-rich sequences in the ladder-like assembly fold into G-quadruplex DNAzyme for visual signal. A model pathogen (Salmonella spp.) and a model plant (MON810 maize) were detected by our sensor with excellent sensitivity and selectivity, demonstrating the universality. The linearity of Salmonella spp. was y (A450) = 0.1571x (the logarithm of concentrations) + 0.4452 (R2 = 0.9903) from 101 cfu/mL to108 cfu/mL with the detection limit of 3 cfu/mL; and the visible semi-quantified detection limit of MON810 maize was 0.1 %. Meanwhile, a recovery and a selective experiment were performed in yogurt starter with Salmonella spp.. Generally, this study provides a dsDNA/ssDNA-switchable colorimetric strategy based on a universal primer and λ exonuclease. A project of compositive suitcase, constituted by a DNA crude extract kit, an isothermal colorimetric kit and a portable spectrophotometer, was developed for versatile detection of different targets for a mobile laboratory. This shows great promise for on-site bioassays in food safety, environmental monitoring and clinical diagnosis.