Responsive helical self-assembly of AgNO3 and melamine through asymmetric coordination for Ag nanochain synthesis

Melamine-Ag with dual functions of electrochemiluminescence luminophore and coreactant accelerators: Construction of MIP/M-Ag@MoS2-QDs sensing platform for specific detection of thiabendazole

A novel self-enhancement molecularly imprinted electrochemiluminescence (ECL) sensor (MIP/M-Ag@MoS₂-QDs/GCE) was constructed to detect thiabendazole (TBZ) in food. Melamine was used as template to chelate Ag⁺ to prepare composite nanomaterials (M-Ag). M-Ag possesses both ECL properties and coreactant catalytic properties, which can realize the self-enhancement of ECL luminophore. MoS₂-QDs with excellent edge activity and electrochemical reaction catalytic activity were used to accelerate the reaction rate of the microsystem and further enhance the ECL intensity. The specific detection method of TBZ was established by investigating the ECL response mechanism and specific recognition mechanism of MIP/M-Ag@MoS₂-QDs/GCE. The ECL intensity was proportioned to the lg C_(TBZ) in the linear range 5 × 10^-8 mol L^-1-5 × 10^-5 mol L^-1 with a limit detection of 1.42 × 10^-8 mol L^-1. The satisfactory recovery rate (83.57%-101.03%) was obtained in sample analysis, which was in good agreement with the analysis result of HPLC.

A selective colorimetric and efficient removal strategy for mercury (II) using mesoporous silver-melamine nanocomposites synthesized by controlled supramolecular self-assembly

Mesoporous silver-melamine (Ag-MA) nanocomposites were synthesized by controlled supramolecular self-assembly with various structural morphologies. It was discovered that the rod-like Ag-MA nanocomposites could present the larger Hg²⁺-enhanced catalysis by forming Ag-Hg alloys. Also, they could display large surface-to-volume area and high aqueous stability for the selective Hg²⁺ enrichment and absorption of Hg²⁺ ions by yielding the stable coordination complexes. A catalysis-based colorimetric method was thus developed using 96-wells plates to probe Hg²⁺ ions in blood and wastewater with the linear Hg²⁺ concentrations ranging from 1.0 nM to 600 nM and 0.50 nM to 700 nM, respectively. Besides, mesoporous Ag-MA absorbents could facilitate the removal of Hg²⁺ ions in wastewater with the removal efficiency up to 99.76 % and the absorption capacity of 598.99 mg g^-1.

Co0.85Se Nanoparticles Encapsulated by Nitrogen-Enriched Hierarchically Porous Carbon for High-Performance Lithium-Ion Batteries

Coordination compound derivates (CCDs) have been widely applied in lithium-ion batteries (LIBs). However, the functionalization of CCDs with open structure and heteroatomic doping is still challenging. Herein, an effective functionalization strategy is presented to prepare a kind of CCD, where Co_0.85Se nanoparticles are encapsulated by nitrogen-enriched hierarchically porous carbon (CS/NPC) based on the heat treatment of a cobalt-complexed hexamethylolmelamine-polyvinylpyrrolidone resin (Co²⁺/HPR). The abundant free volume and enriched N species of the HPR are responsible for the hierarchically porous configuration and high N-doping of the composites. By controlling the content of cobalt salt and the heating rate, high specific surface area (440.7 m² g^-1), high N-doping (8.54 atom %), and suitable mass loading of Co_0.85Se (55.5%) were simultaneously achieved in CS-2/NPC-5, which delivers high reversible capacity (758.5 mAh g^-1 at 0.1 A g^-1), outstanding rate capability (401.7 mAh g^-1 at 5 A g^-1), and excellent cycling durability (638.4 mAh g^-1 at 1 A g^-1 after 200 cycles), suggesting a promising candidate for LIB anode materials.

A hybrid hydrogel with in situ formed Ag-nanoparticles within 3D networks that exhibits broad antibacterial activities

A new hybrid hydrogel was constructed by in situ forming Ag NPs within the 3D network of a hydrogel that exhibits both excellent injectability and broad antibacterial activities, which makes it a potential candidate for various biomedical applications.

Zigzag-Shaped Silver Nanoplates: Synthesis via Ostwald Ripening and Their Application in Highly Sensitive Strain Sensors

Zigzag-shaped Ag nanoplates display unique anisotropic planar structures with unusual jagged edges and relatively large lateral dimensions. These characteristics make such nanoplates promising candidates for metal inks in printed electronics, which can be used for realizing stretchable electrodes. In the current work, we used a one-pot coordination-based synthetic strategy to synthesize zigzag-shaped Ag nanoplates. In the synthetic procedure, cyanuric acid was used both as a ligand of the Ag⁺ ion, hence producing complex structures and controlling the kinetics of the reduction of the cation, and as a capping agent that promoted the lateral growth of the Ag nanoplates. Hence, cyanuric acid played a crucial role in the formation of zigzag-shaped nanoplates. In contrast to previous studies that reported oriented attachment to be the predominant mechanism responsible for the growth of zigzag-shaped nanoplates, Ostwald ripening was the dominant growth mechanism in the current work. Our findings on the particle morphology and crystalline structure of the Ag nanoplates motivated us to use them as conductive materials for stretchable strain sensors. Strain sensors based on nanocomposites of our zigzag-shaped Ag nanoplate and polydimethylsiloxane in the form of a sandwich structure were successfully produced by following a simple, low-cost, and solution-processable method. The strain sensors exhibited extremely high sensitivity (gauge factor ≈ 2000), high stretchability with a linear response (≈27%), and high reliability, all of which allowed the sensor to monitor diverse human motions, including joint movement and phonation.

Hydrogels Based on Ag+ -Modulated Assembly of 5'-Adenosine Monophosphate for Enriching Biomolecules

Supramolecular hydrogels obtained by combining 5'-adenosine monophosphate (AMP) with Ag⁺ were fabricated in this work. Their gelation capability was enhanced by increasing the concentration of Ag⁺ or decreasing the pH. The gels are very sensitive to light, which endows them with potential applications as visible-light photosensitive materials. Coordination between the nucleobase of AMP and Ag⁺ , as well as π-π stacking of nucleobases, are considered to be the main driving forces for self-assembly. The hydrogels successfully achieved the encapsulation and enrichment of biomolecules. Hydrogen bonding between the amino group of guest molecules and silver nanoparticles along the nanofibers drives the enrichment and is considered to be a crucial interaction.

A high-throughput fluorimetric microarray with enhanced fluorescence and suppressed "coffee-ring" effects for the detection of calcium ions in blood

A rapid, ultrasensitive, and high-throughput fluorimetric microarray method has been developed using hydrophobic pattern as the microarray substrate and 3-aminopropyltriethoxysilane-coupled carboxylic acid calcium (APS-CCA) as the fluorescent probes for sensing Ca2+ ions in blood. The hydrophobic pattern of the developed Ca2+ analysis microarray could largely suppress the "coffee-ring" effects to facilitate the better distribution density of testing microspots toward the high-throughput detections, and especially prevent the cross-contamination of the multiple samples between adjacent microspots. Moreover, the use of APS matrix could endow the CCA probe the enhanced environmental stability and fluorescence intensity, which is about 2.3-fold higher than that of free CCA. The interactions between APS-CCA and Ca2+ ions were systematically characterized by UV-vis and fluorescence measurements including microscopy imaging. It was demonstrated that the fluorimetric microarray could display the strong capacity of specifically sensing Ca2+ ions with the minimal interferences from blood backgrounds. Such an APS-CCA-based fluorimetric microarray can allow for the analysis of Ca2+ ions down to 0.0050 mM in blood, promising a highly sensitive and selective detection candidate for Ca2+ ions to be applied in the clinical laboratory.

Bifunctional Ag/C3N4.5 composite nanobelts for photocatalysis and antibacterium

Multiple functions can be achieved in carbon nitride-based composite nanomaterials by tuning their components and structures. Here, we report on a large-scale synthesis of novel bifunctional Ag/C3N4.5 composite nanobelts (CNBs) with efficient photocatalytic and antibacterial activity. The Ag/C3N4.5 CNBs were synthesized in high yield by a two-step route including a homogeneous precipitation process and a subsequent calcination treatment. The structural, morphological, compositional, and spectroscopic characterizations revealed that the Ag/C3N4.5 CNBs are composed of N-deficient melem ultrathin nanobelts and crystalline Ag nanoparticles attached to the surface of the nanobelts with good contact. The band gap of the Ag/C3N4.5 CNBs is determined to be about 3.04 eV. The efficient photocatalytic and antibacterial activities of the composite nanomaterials are verified by testing the degradation of Rhodamine B (RhB) and the inhibition zone to bacterium E. coli. The work provides a facile route to bifunctional carbon nitride-based composites with potential applications in the fields of the environment and biology.

Ultrafine Au and Ag Nanoparticles Synthesized from Self-Assembled Peptide Fibers and Their Excellent Catalytic Activity

The self-assembly of an amphiphilic peptide molecule to form nanofibers facilitated by Ag(+) ions was investigated. Ultrafine AgNPs (NPs=nanoparticles) with an average size of 1.67 nm were synthesized in situ along the fibers due to the weak reducibility of the -SH group on the peptide molecule. By adding NaBH4 to the peptide solution, ultrafine AgNPs and AuNPs were synthesized with an average size of 1.35 and 1.18 nm, respectively. The AuNPs, AgNPs, and AgNPs/nanofibers all exhibited excellent catalytic activity toward the reduction of 4-nitrophenol, with turnover frequency (TOF) values of 720, 188, and 96 h(-1) , respectively. Three dyes were selected for catalytic degradation by the prepared nanoparticles and the nanoparticles showed selective catalysis activity toward the different dyes. It was a surprising discovery that the ultrafine AuNPs in this work had an extremely high catalytic activity toward methylene blue, with a reaction rate constant of 0.21 s(-1) and a TOF value of 1899 h(-1) .

Nanoarchitectonics for Dynamic Functional Materials from Atomic-/Molecular-Level Manipulation to Macroscopic Action

Objects in all dimensions are subject to translational dynamism and dynamic mutual interactions, and the ability to exert control over these events is one of the keys to the synthesis of functional materials. For the development of materials with truly dynamic functionalities, a paradigm shift from "nanotechnology" to "nanoarchitectonics" is proposed, with the aim of design and preparation of functional materials through dynamic harmonization of atomic-/molecular-level manipulation and control, chemical nanofabrication, self-organization, and field-controlled organization. Here, various examples of dynamic functional materials are presented from the atom/molecular-level to macroscopic dimensions. These systems, including atomic switches, molecular machines, molecular shuttles, motional crystals, metal-organic frameworks, layered assemblies, gels, supramolecular assemblies of biomaterials, DNA origami, hollow silica capsules, and mesoporous materials, are described according to their various dynamic functions, which include short-term plasticity, long-term potentiation, molecular manipulation, switchable catalysis, self-healing properties, supramolecular chirality, morphological control, drug storage and release, light-harvesting, mechanochemical transduction, molecular tuning molecular recognition, hand-operated nanotechnology.

Electrically bistable Ag nanocrystal-embedded metal–organic framework microneedles

Electrically bistable Ag nanocrystal-embedded metal–organic frameworks (MOF) were synthesized using a one-pot synthetic method by introducing melamine into a polyol process for the synthesis of Ag nanocrystals.

Highly dispersed Ag nanoparticles embedded in alumina nanobelts as excellent surface-enhanced Raman scattering substrates

The Ag/Al₂O₃ composite nanobelts with nearly monodispersed Ag nanoparticles embedded in alumina nanobelts show excellent SERS performances for the R6G probe molecule.

Self-Assembled Peptide Nanofibers Encapsulated with Superfine Silver Nanoparticles via Ag⁺ Coordination

We demonstrate that a glutanthione-based oligopeptide, Fmoc-GCE, could self-assemble into nanofibers induced by Ag(+) ions in NaOH solution. During the self-assembly process, the superfine silver nanoparticles were in situ produced on the nanofibers. On the basis of a series of characterizations, we proposed the possible mechanism of the self-assembly, for which the coordination interaction between Fmoc-GCE and Ag(+) ions as well as the π-π stacking of fluorenyl groups were the main driving forces of the self-assembled nanofibers. At appropriate compositions, the 3D networks of Fmoc-GCE/NaOH/Ag(+) nanofibers could further form metallogel, which was responsive to pyridine and melamine, which could coordination with Ag(+) ions. Moreover, the nanofibers encapsulated with superfine silver nanoparticles exhibited catalytic ability in degradation of the azo dye and the antibacterial properties to both Gram negative (E. coli) and Gram positive (S. aureus) bacteria.

Controlled preparation of porous TiO2-Ag nanostructures through supramolecular assembly for plasmon-enhanced photocatalysis

By templating Ag(+)-induced supramolecular assembly at different temperatures, porous TiO2-Ag nanotubes and nanospheres are fabricated in a controlled manner due to the effect of Rayleigh instability. Compared with traditional TiO2 nanoparticles, TiO2-Ag nanostructures above show much more extensive visible light absorption and exhibit the noticeably plasmon-enhanced photocatalysis because of the existence of Ag nanoparticles.

Dual-tuning multidimensional superstructures based on a T-shaped molecule: vesicle, helix, membrane and nanofiber-constructed gel

Dual-tuning self-assembly of Fmoc–Gly (a T-shape molecule) supramolecular self assembly was firstly reported here.

Dynamic self-assembly of coordination polymers in aqueous solution

The construction of supramolecular polymers has been intensively pursued because the nanostructures formed through weak non-covalent interactions can be triggered by external stimuli leading to smart materials and sensors. Self-assemblies of coordination polymers consisting of metal ions and organic ligands in aqueous solution also provide particular contributions in this area. The main motivation for developing those coordination polymers originates from the value-added combination between metal ions and ligands. This review highlights the recent progress of the dynamic self-assembly of coordination polymers that result from the sophisticated molecular design, towards fabricating stimuli-responsive systems and bio-related materials. Dynamic structural changes and switchable physical properties triggered by various stimuli are summarized. Finally, the outlook for aqueous nanostructures originated from the dynamic self-assembly of coordination polymers is also presented.

Visualized detection of melamine in milk by supramolecular hydrogelations

We reported on a simple assay for visualized detection of melamine in milk by supramolecular hydrogelations.