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The identification of each cell type is essential for understanding multicellular communities. Antibodies set as biomarkers have been the main toolbox for cell-type recognition, and chemical probes are emerging surrogates. Herein we report the first small-molecule probe, CDgB, to discriminate B lymphocytes from T lymphocytes, which was previously impossible without the help of antibodies. Through the study of the origin of cell specificity, we discovered an unexpected novel mechanism of membrane-oriented live-cell distinction. B cells maintain higher flexibility in their cell membrane than T cells and accumulate the lipid-like probe CDgB more preferably. Because B and T cells share common ancestors, we tracked the cell membrane changes of the progenitor cells and disclosed the dynamic reorganization of the membrane properties over the lymphocyte differentiation progress. This study casts an orthogonal strategy for the small-molecule cell identifier and enriches the toolbox for live-cell distinction from complex cell communities.
Assuntos
Linfócitos B/citologia , Membrana Celular/metabolismo , Corantes Fluorescentes/química , Linfócitos T/citologia , Animais , Linfócitos B/química , Linfócitos B/imunologia , Células da Medula Óssea/citologia , Células da Medula Óssea/metabolismo , Diferenciação Celular , Membrana Celular/química , Citometria de Fluxo , Lipidômica , Camundongos , Linfócitos T/química , Linfócitos T/imunologiaRESUMO
Rice husk is one of the most abundant biomass resources in the world, yet it is not effectively used. This study focuses on the sustainably rice-husk-extracted lignin, nano-lignin (n-Lignin), lignin-capped silver nanoparticles (LCSN), n-Lignin-capped silver nanoparticles (n-LCSN), and lignin-capped silica-silver nanoparticles (LCSSN), and using them for antibacterial activities. The final n-Lignin-based products had a sphere-like structure, of which the size varied between 50 and 80 nm. We found that while n-Lignin and lignin were less effective against Escherichia coli than against Staphylococcus aureus, n-Lignin/lignin-based hybrid materials, i.e., n-LCSN, LCSN, and LCSSN, were better against E. coli than against S. aureus. Interestingly, the antimicrobial behaviors of n-LCSNs could be further improved by decreasing the size of n-Lignin. Considering the facile, sustainable, and eco-friendly method that we have developed here, it is promising to use n-Lignin/lignin-based materials as highly efficient antimicrobials without environmental concerns.
Assuntos
Nanopartículas Metálicas , Prata , Antibacterianos/química , Antibacterianos/farmacologia , Escherichia coli , Lignina/química , Lignina/farmacologia , Nanopartículas Metálicas/química , Testes de Sensibilidade Microbiana , Dióxido de Silício , Prata/química , Prata/farmacologia , Staphylococcus aureusRESUMO
Hierarchical self-assembly of building blocks over multiple length scales is ubiquitous in living organisms. Microtubules are one of the principal cellular components formed by hierarchical self-assembly of nanometer-sized tubulin heterodimers into protofilaments, which then associate to form micron-length-scale, multi-stranded tubes. This peculiar biological process is now mimicked with a fully synthetic molecule, which forms a 1:1 host-guest complex with cucurbit[7]uril as a globular building block, and then polymerizes into linear poly-pseudorotaxanes that associate laterally with each other in a self-shape-complementary manner to form a tubular structure with a length over tens of micrometers. Molecular dynamic simulations suggest that the tubular assembly consists of eight poly-pseudorotaxanes that wind together to form a 4.5â nm wide multi-stranded tubule.
Assuntos
Microtúbulos/química , Polímeros/química , Hidrocarbonetos Aromáticos com Pontes/química , Imidazóis/química , Microscopia de Força Atômica , Microscopia Eletrônica de Transmissão , Microtúbulos/metabolismo , Simulação de Dinâmica Molecular , Rotaxanos/químicaRESUMO
Transient self-assembling systems often suffer from accumulation of chemical wastes that interfere with the formation of pristine self-assembled products in subsequent cycles. Herein, we report the transient crystallization of a cucurbit[8]uril-based host-guest complex, preventing the accumulation of chemical wastes. Base-catalyzed thermal decarboxylation of trichloroacetic acid that chemically fuels the crystallization process dissolves the crystals, and produces volatile chemical wastes that are spontaneously removed from the solution. With such self-clearance process, no significant damping in the formation of the crystals was observed. The morphology and structural integrity of the crystals was also maintained in subsequent cycles. The concept may be further extended to obtain other temporally functional materials, quasicrystals, etc., based on stimuli-responsive guest molecules.
RESUMO
Single-molecule surface-enhanced Raman spectroscopy (SERS) offers new opportunities for exploring the complex chemical and biological processes that cannot be easily probed using ensemble techniques. However, the ability to place the single molecule of interest reliably within a hot spot, to enable its analysis at the single-molecule level, remains challenging. Here we describe a novel strategy for locating and securing a single target analyte in a SERS hot spot at a plasmonic nanojunction. The "smart" hot spot was generated by employing a thiol-functionalized cucurbit[6]uril (CB[6]) as a molecular spacer linking a silver nanoparticle to a metal substrate. This approach also permits one to study molecules chemically reluctant to enter the hot spot, by conjugating them to a moiety, such as spermine, that has a high affinity for CB[6]. The hot spot can accommodate at most a few, and often only a single, analyte molecule. Bianalyte experiments revealed that one can reproducibly treat the SERS substrate such that 96% of the hot spots contain a single analyte molecule. Furthermore, by utilizing a series of molecules each consisting of spermine bound to perylene bisimide, a bright SERS molecule, with polymethylene linkers of varying lengths, the SERS intensity as a function of distance from the center of the hot spot could be measured. The SERS enhancement was found to decrease as 1 over the square of the distance from the center of the hot spot, and the single-molecule SERS cross sections were found to increase with AgNP diameter.
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Serendipitously, mono-allyloxylated cucurbit[7]uril (AO1 CB[7]) was discovered to act as an unconventional amphiphile which self-assembles into light-responsive vesicles (AO1 CB[7]VC) in water. Although the mono-allyloxy group, directly tethered on the periphery of CB[7], is much shorter (C4) than the hydrophobic tails of conventional amphiphiles, it played an important role in vesicle formation. Light-activated transformation of the allyloxy group by conjugation with glutathione was exploited as a remote tool to disrupt the vesicle. The vesicle showed on-demand release of cargo upon irradiation by a laser, after they were internalized into cancer cells. This result demonstrated the potential of AO1 CB[7]VC as a new type of light-responsive intracellular delivery vehicle for the release of therapeutic cargo, within cells, on demand.
RESUMO
Over the past decades, numerous efforts have been devoted to synthesizing nanostructured materials with specific morphology because their size and shape play an important role in determining their functions. Self-assembly using weak and reversible interactions or bonds has provided synthetic routes toward various nanostructures because it allows a "self-checking" and "self-error-correcting" process under thermodynamic control. By contrast, the use of irreversible covalent bonds, despite the potential to generate more robust structures, has been disfavored in the synthesis of well-defined nanomaterials largely due to the lack of such self-error-correcting mechanisms. To date, the use of irreversible bonds is largely limited to covalent fixation of preorganized building blocks on a template, which, though capable of producing shape-persistent and robust nanostructured materials, often requires a laborious and time-consuming multistep processes. Constructing well-defined nanostructures by self-assembly using irreversible covalent bonds without help of templates or preorganization of components remains a challenge. This Account describes our recent discoveries and progress in self-assembly of nanostructured materials through strong, practically irreversible covalent bond formation and their applications in various areas including drug delivery, anticancer therapy, and heterogeneous catalysis. The key to the success of this approach is the use of rationally designed building blocks possessing multiple in-plane reactive groups at the periphery. These blocks can then successfully grow into flat oligomeric patches through irreversible covalent bond formation without the aid of preorganization or templates. Further growth of the patches with or without curvature generation drives the system to the formation of polymer nanocapsules, two-dimensional (2D) polymer films, and toroidal nanotubular microrings. Remarkably, the final morphology can be specified by a few simple parameters: the reaction medium, bending rigidity of the system, and orientation of the reactive groups. Theoretical studies support the spontaneous formation of such nanostructured materials in terms of energetics and successfully predict or explain their size distributions. Although the lack of self-error-correcting mechanisms results in defect sites in these nanostructures, the high efficiency and relative simplicity of our novel approach demonstrates the potential power of using irreversible covalent bonds to generate a diverse range of shape-persistent and robust nanostructures that is likely to enrich the repertoire of self-assembled nanomaterials.
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Developing a material that can combat antibiotic-resistant bacteria, a major global health threat, is an urgent requirement. To tackle this challenge, we synthesized a multifunctional subphthalocyanine (SubPc) polymer nanosphere that has the ability to target, label, and photoinactivate antibiotic-resistant bacteria in a single treatment with more than 99 % efficiency, even with a dose as low as 4.2â J cm(-2) and a loading concentration of 10â nM. The positively charged nanosphere shell composed of covalently linked SubPc units can increase the local concentration of photosensitizers at therapeutic sites. The nanosphere shows superior performance compared to corresponding monomers presumably because of their enhanced water dispersibility, higher efficiency of singlet-oxygen generation, and phototoxicity. In addition, this material is useful in fluorescence labeling of living cells and shows promise in photoacoustic imaging of bacteria inâ vivo.
Assuntos
Antibacterianos/farmacologia , Resistência Microbiana a Medicamentos/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Indóis/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Nanosferas/química , Fármacos Fotossensibilizantes/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Relação Dose-Resposta a Droga , Escherichia coli/citologia , Fluorescência , Indóis/síntese química , Indóis/química , Isoindóis , Staphylococcus aureus Resistente à Meticilina/citologia , Testes de Sensibilidade Microbiana , Estrutura Molecular , Tamanho da Partícula , Fármacos Fotossensibilizantes/síntese química , Fármacos Fotossensibilizantes/química , Relação Estrutura-AtividadeRESUMO
A facile method has been developed for synthesizing polymer nanocapsules and thin films using multiple in-plane stitching of monomers by the formation of reversible disulfide linkages. Owing to the reversibility of the disulfide linkages, the nanostructured materials readily transform their structures in response to environmental changes at room temperature. For example, in reducing environments, the polymer nanocapsules release loaded cargo molecules. Moreover, reversible morphological transformations between these structures can be achieved by simple solvent exchanges. This work is a novel approach for the formation of robust nano/microstructured materials that dynamically respond to environmental stimuli.
Assuntos
Dissulfetos/química , Nanocápsulas/química , Polímeros/síntese química , Termodinâmica , Conformação Molecular , Tamanho da Partícula , Polímeros/química , Propriedades de SuperfícieRESUMO
A facile synthesis of highly stable, water-dispersible metal-nanoparticle-decorated polymer nanocapsules (M@CB-PNs: M=Pd, Au, and Pt) was achieved by a simple two-step process employing a polymer nanocapsule (CB-PN) made of cucurbit[6]uril (CB[6]) and metal salts. The CB-PN serves as a versatile platform where various metal nanoparticles with a controlled size can be introduced on the surface and stabilized to prepare new water-dispersible nanostructures useful for many applications. The Pd nanoparticles on CB-PN exhibit high stability and dispersibility in water as well as excellent catalytic activity and recyclability in carbon-carbon and carbon-nitrogen bond-forming reactions in aqueous medium suggesting potential applications as a green catalyst.
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The design and synthesis of two-dimensional (2D) polymers is a challenging task, hitherto achieved in solution only through the aid of a solid surface "template" or preorganization of the building blocks in a 2D confined space. We present a novel approach for synthesizing free-standing, covalently bonded, single-monomer-thick 2D polymers in solution without any preorganization of building blocks on solid surfaces or interfaces by employing shape-directed covalent self-assembly of rigid, disk-shaped building blocks having laterally predisposed reactive groups on their periphery. We demonstrate our strategy through a thiol-ene "click" reaction between (allyloxy)12CB[6], a cucurbit[6]uril (CB[6]) derivative with 12 laterally predisposed reactive alkene groups, and 1,2-ethanedithiol to synthesize a robust and readily transferable 2D polymer. We can take advantage of the high binding affinity of fully protonated spermine (positive charges on both ends) to CB[6] to keep each individual polymer sheet separated from one another by electrostatic repulsion during synthesis, obtaining, for the first-time ever, a single-monomer-thick 2D polymer in solution. The arrangement of CB[6] repeating units in the resulting 2D polymer has been characterized using gold nanoparticle labeling and scanning transmission electron microscopy. Furthermore, we have confirmed the generality of our synthetic approach by applying it to different monomers to generate 2D polymers. Novel 2D polymers, such as our CB[6] derived polymer, may be useful in selective transport, controlled drug delivery, and chemical sensing and may even serve as well-defined 2D scaffolds for ordered functionalization and platforms for bottom-up 3D construction.
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Although metastable crystal structures have received much attention owing to their utilization in various fields, their phase-transition to a thermodynamic structure has attracted comparably little interest. In the case of nanoscale crystals, such an exothermic phase-transition releases high energy within a confined surface area and reconstructs surface atomic arrangement in a short time. Thus, this high-energy nanosurface may create novel crystal structures when some elements are supplied. In this work, the creation of a ruthenium carbide (RuCX , X < 1) phase on the surface of the Ru nanocrystal is discovered during phase-transition from cubic-close-packed to hexagonal-close-packed structure. When the electrocatalytic hydrogen evolution reaction (HER) is tested in alkaline media, the RuCX exhibits a much lower overpotential and good stability relative to the counterpart Ru-based catalysts and the state-of-the-art Pt/C catalyst. Density functional theory calculations predict that the local heterogeneity of the outermost RuCX surface promotes the bifunctional HER mechanism by providing catalytic sites for both H adsorption and facile water dissociation.
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Naturally occurring spatiotemporal patterns typically have a predictable pattern design and are reproducible over several cycles. However, the patterns obtained from artificially designed out-of-equilibrium chemical oscillating networks (such as the Belousov-Zhabotinsky reaction for example) are unpredictable and difficult to control spatiotemporally, albeit reproducible over subsequent cycles. Here, we show that it is possible to generate reproducible spatiotemporal patterns in out-of-equilibrium chemical reactions and self-assembling systems in water in the presence of sound waves, which act as a guiding physical stimulus. Audible sound-induced liquid vibrations control the dissolution of atmospheric gases (such as O2 and CO2) in water to generate spatiotemporal chemical patterns in the bulk of the fluid, segregating the solution into spatiotemporal domains having different redox properties or pH values. It further helps us in the organization of transiently formed supramolecular aggregates in a predictable spatiotemporal manner.
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Cucurbituril-based nanoparticles (CB[6]NPs) serve as new efficient vehicles for delivery of hydrophobic drugs, which have unique features including (1) a high drug loading capacity and efficiency, (2) noncovalently tunable surfaces, (3) efficient delivery of hydrophobic drugs into a cancer cell by receptor-mediated endocytosis, and (4) facile release of drugs into cytoplasm, which enhances the pharmaceutical effects of the drugs.
Assuntos
Sistemas de Liberação de Medicamentos , Nanopartículas/química , Preparações Farmacêuticas/química , Veículos Farmacêuticos/química , Corantes , Citoplasma/efeitos dos fármacos , Citoplasma/metabolismo , Células HeLa , Humanos , Compostos Macrocíclicos/química , Microscopia Confocal , Oxazinas , Tamanho da Partícula , Fotoquímica , Solubilidade , ÁguaRESUMO
Surface-enhanced Raman scattering (SERS) is a powerful technique that enhances Raman signals by adsorbing probe molecules on rough metal surfaces. However, SERS is limited because target molecules must strongly interact with metal to enhance a stable Raman signal. In this study, to improve long-term SERS stability, we use cucurbit[7]urils (CB[7]) as bridge molecules and sample containers to probe Rhodamine 6G (R6G) molecules. We observed interactions between gold nanorods (AuNRs) and CB[7] via aggregate formation, which enhanced the Raman signal and improved long-term R6G probe stability by up to 20 days when encapsulated within CB[7] during SERS analysis.
RESUMO
Novel hybrid nanomaterials comprising metal-organic framework compounds carbonised in the presence of biomass material derived from rice husk have been investigated as a new class of sustainable supercapacitor materials for electrochemical energy storage. Specifically, two synthetic routes were employed to grow Co/Mn metal-organic framework compounds in the channels of rice husks, which had been activated previously by heat treatment in air at 400 °C to produce a highly porous network. Pyrolysis of these hybrid materials under nitrogen at 700 °C for 6 h produced metal-containing phases within the nanocarbon, comprising intimate mixtures of Co, MnO and CoMn2O4. The materials thus produced are characterized in detail using a range of physical methods including XRD, electron microscopy and X-ray photoelectron spectroscopy. The synthetic pathway to the metal-organic framework compound is shown to influence significantly the physical properties of the resulting material. Electrochemical evaluation of the materials fabricated revealed that higher specific capacitances were obtained when smaller crystallite sized bimetallic Co/Mn-MOFs were grown inside the rice husks channels compared to larger crystallite sizes. This was in-part due to increased metal oxide loading into the rice husk owing to the smaller crystallite size as well as the increased pseudocapacitance exhibited by the smaller crystallite sizes and increased porosity.
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We report a new approach for photoinduced reduction of Cu2+ that will enrich the structural diversity of coordination complexes and be a valuable contributor to the development of Cu+/Cu0-based catalysts. To realize controlled Cu2+ reduction, coumarin as a triplet quencher of excited benzophenone was tethered to Cu(ii)-metal-organic polyhedra (MOPs). The photoinduced catalytic activity of the coumarin-MOPs was also examined in a Cu(i)-catalyzed azide-alkyne cycloaddition (CuAAC).
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A permselective membrane with a non-covalently tailorable surface has been fabricated by deposition of a cucurbit[6]uril-based 2D polymer film onto a simple support membrane. Tuneable permselectivity of this membrane has been achieved through non-covalent surface modification using the remarkable host-guest chemistry of the incorporated cucurbit[6]uril units.
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New wedge-shaped thermotropic liquid crystalline materials containing a guanidinium moiety at the apex organize into various supramolecular structures such as hexagonal columnar, rectangular columnar and Pm3n cubic mesophases depending on anions illustrating guest-directed self-organization in mesophases.
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A simple modular aptamer-based sensor (aptasensor) platform was prepared by combining the merits of the rapid and efficient preparation of a self-assembled monolayer of cucurbit[7]uril (CB[7] SAM) and the strong and specific binding affinity of CB[7] to ferrocenemethylammonium (FA), as an ultrastable supramolecular linker, to immobilize aptamers on CB[7] SAM.