RESUMO
Two major hurdles in NP-based catalysis are the aggregation of the NPs and their recycling. Immobilization of NPs onto a 2D support is the most promising strategy to overcome these difficulties. Herein, amphiphilicity-driven self-assembly of galactose-hexaphenylbenzene-based amphiphiles into galactose-decorated 2D nanosheet is reported. The extremely dense decoration of reducing sugar on the surface of the sheets is used for the inâ situ synthesis and immobilization of ultrafine catalytically active AgNPs by using Tollens' reaction. The potential of the system as a catalyst for the reduction of various nitroaromatics is demonstrated. Enhanced catalytic activity is observed for the immobilized AgNPs when compared to the corresponding discrete AgNPs. Recovery of the catalytic system from the reaction mixture by ultrafiltration and its subsequent recycling for several cycles without dropping its activity is shown. This is the first report demonstrating the inâ situ synthesis and immobilization of ultrafine AgNPs onto a 2D nanosheet that exhibits excellent catalytic performance for the reduction of nitroaromatics.
Assuntos
Galactose , Nanopartículas Metálicas , Catálise , PrataRESUMO
Two-component organogels offer several advantages over one-component gels, but their design is highly challenging. Hence, it is extremely important to design new approaches for the crafting of two-component organogels with interesting optical and mechanical properties. Herein, we report the design of a new class of two-component supergelators obtained from the assembly between acid functionalized tetraphenylethylene (TPE)-based dendrons and alkylated melamine. No gelation behaviour is observed for the individual components, but interestingly, remarkable gelation behaviour is observed for their hydrogen-bonded complex. The primary driving force responsible for the gelation is the strong π-π stacking interaction of TPE units. Because of the strong π-stacking of TPEs in the gel state, the C(sp2)-C(sp2) bond rotation of the TPE segment is completely arrested in the gel state, which results in intense fluorescence emission of the gels. Furthermore, excellent elastic response is observed for the gels as evident from their high storage modulus compared to loss modulus values. Our results clearly demonstrate that by the appropriate selection of the molecular components, this approach can be applied for the creation of functional nanomaterials with emergent properties absent in the individual blocks.
RESUMO
High aspect ratio, sugar-decorated 2D nanosheets are ideal candidates for the capture and agglutination of bacteria. Herein, the design and synthesis of two carbohydrate-based Janus amphiphiles that spontaneously self-assemble into high aspect ratio 2D sheets are reported. The unique structural features of the sheets include the extremely high aspect ratio and dense display of galactose on the surface. These structural characteristics allow the sheet to act as a supramolecular 2D platform for the capture and agglutination of E. coli through specific multivalent noncovalent interactions, which significantly reduces the mobility of the bacteria and leads to the inhibition of their proliferation. Our results suggest that the design strategy demonstrated here can be applied as a general approach for the crafting of biomolecule-decorated 2D nanosheets, which can perform as 2D platforms for their interaction with specific targets.
Assuntos
Dendrímeros/metabolismo , Escherichia coli/metabolismo , Galactose/química , Nanoestruturas/química , Aglutinação/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Dendrímeros/química , Humanos , Nanopartículas Metálicas/química , Microscopia de Força Atômica , Nanoestruturas/toxicidade , Prata/químicaRESUMO
Crafting of chiral plasmonic nanostructures is extremely important and challenging. DNA-directed organization of nanoparticle on a chiral template is the most appealing strategy for this purpose. Herein, we report a supramolecular approach for the design of DNA-decorated, helically twisted nanoribbons through the amphiphilicity-driven self-assembly of a new class of amphiphiles derived from DNA and hexaphenylbenzene (HPB). The ribbons are self-assembled in a lamellar fashion through the hydrophobic interactions of HPB. The transfer of molecular chirality of ssDNA into the HPB core results in the bias of one of the chiral propeller conformations for HPB and induces a helical twist into the lamellar packing, and leads to the formation of DNA-wrapped nanoribbons with M-helicity. The potential of the ribbon to act as a reversible template for the 1D chiral organization of plasmonic nanomaterials through DNA hybridization is demonstrated.
RESUMO
Preventing the aggregation of NPs and their recovery are the two major hurdles in NP based catalysis. Immobilization of NPs on a support has proven to be a promising strategy to overcome these difficulties. Herein we report the design of high aspect ratio two-dimensional (2D) crystalline DNA nanosheets formed from the amphiphilicity-driven self-assembly of DNA-tetraphenylethylene amphiphiles and also demonstrate the potential of DNA nanosheets for the immobilization of catalytically active NPs. The most remarkable feature of this approach is the high loading of NPs in a non-aggregated manner, and hence exhibiting enhanced catalytic activity. Recycling of NP loaded nanosheets for several cycles without reduction in catalytic efficiency by simple ultrafiltration is also demonstrated.
RESUMO
Nanogels made of biomolecules are one of the potential candidates as a nanocarrier for drug delivery applications. The unique structural characteristics and excellent biocompatibility of DNA suggest that DNA nanogels would be an ideal candidate. Herein, a general design strategy for the crafting of DNA nanogels with controllable size using the multivalent host-guest interaction between ß-CD functionalized branched DNA nanostructures as the host and a star-shaped adamantyl-terminated 8-arm poly(ethylene glycol) polymer as the guest is reported. Our results reveal that multivalent host-guest interactions are necessary for the nanogel formation. Nanogels exhibit excellent biocompatibility, good cell permeability and high drug encapsulation ability, which are promising features for their application as a drug carrier. The encapsulation of doxorubicin, an anticancer drug, inside the hydrophobic network of the nanogel and its delivery into cancer cells are also reported. We hope that the general design strategy demonstrated for the creation of DNA nanogels may encourage other researchers to use this approach for the design of DNA nanogels of other DNA nanostructures, and explore the potential of DNA nanogels in drug delivery applications.
Assuntos
DNA/química , Portadores de Fármacos/química , Géis/química , Nanoestruturas/química , Polietilenoglicóis , Doxorrubicina/administração & dosagem , Células HeLa , Humanos , Células MCF-7 , PolietilenoiminaRESUMO
Design and synthesis of high aspect ratio 2D nanosheets with surface having ultradense array of information-rich molecule such as DNA is extremely challenging. Herein, we report a universal strategy based on amphiphilicity-driven self-assembly for the crafting of high aspect ratio, 2D sheets that are densely surface-decorated with DNA. Microscopy and X-ray analyses have shown that the sheets are crystalline. The most unique feature of the sheets is DNA-directed surface addressability, which is demonstrated through the decoration of either faces of the sheet with gold nanoparticles through sequence-specific DNA hybridization. Our results suggest that this design strategy can be applied as a general approach for the synthesis of DNA decorated high aspect ratio sheets, which may find potential applications in materials science, drug delivery, and nanoelectronics.
Assuntos
DNA/química , Ouro/química , Nanopartículas Metálicas/química , Hibridização de Ácido NucleicoRESUMO
A pH-responsive DNAsome derived from the amphiphilicity-driven self-assembly of DNA amphiphile containing C-rich DNA sequence is reported. The acidification of DNAsome induces a structural change of C-rich DNA from random coil to an i-motif structure that triggers the disassembly of DNAsome and its subsequent morphological transformation into an open entangled network. The encapsulation of a hydrophobic guest into the membrane of DNAsome and its pH-triggered release upon acidification of DNAsome is also demonstrated.
RESUMO
DNA nanostructures have found potential applications in various fields including nanotechnology, materials science and nanomedicine, hence the design and synthesis of DNA nanostructures is extremely important. Self-assembly of DNA amphiphiles provides an efficient strategy for the crafting of soft DNA nanostructures. However, the synthesis of DNA amphiphiles is always challenging. Herein, we show a non-covalent approach based on the host-guest interaction between ß-CD and adamantane for the synthesis of DNA amphiphiles, and report their amphiphilicity-driven self-assembly into DNA decorated vesicles. The DNA-directed surface addressability of the vesicles is demonstrated through their surface decoration with Au-NPs through DNA hybridization. Our results suggest that the non-covalent approach represents a simple, efficient and universal method for the synthesis of DNA amphiphiles, and provides an excellent strategy for the creation of smart DNA nanostructures.
Assuntos
DNA/química , Nanoestruturas/química , Química Click , Hibridização de Ácido NucleicoRESUMO
DNA based spherical nanostructures are one of the promising nanostructures for several biomedical and biotechnological applications due to their excellent biocompatibility and DNA-directed surface addressability. Herein, we report the synthesis and amphiphilicity-driven self-assembly of two classes of DNA (hydrophilic)-chromophore (hydrophobic) hybrid amphiphiles into spherical nanostructures. A solid-phase "click" chemistry based modular approach is demonstrated for the synthesis of DNA-chromophore amphiphiles. Various spectroscopic and microscopic analyses reveal the self-assembly of the amphiphiles into vesicular and micellar assemblies with the corona made of hydrophilic DNA and the hydrophobic chromophoric unit as the core of the spherical nanostructures.
Assuntos
Benzopiranos/química , DNA/química , Indóis/química , Nanoestruturas/química , Porfirinas/química , Tensoativos/síntese química , Química Click , Interações Hidrofóbicas e Hidrofílicas , Micelas , Tensoativos/químicaRESUMO
Surface-addressable nanostructures of linearly π-conjugated molecules play a crucial role in the emerging field of nanoelectronics. Herein, by using DNA as the hydrophilic segment, we demonstrate a solid-phase "click" chemistry approach for the synthesis of a series of DNA-chromophore hybrid amphiphiles and report their reversible self-assembly into surface-engineered vesicles with enhanced emission. DNA-directed surface addressability of the vesicles was demonstrated through the integration of gold nanoparticles onto the surface of the vesicles by sequence-specific DNA hybridization. This system could be converted to a supramolecular light-harvesting antenna by integrating suitable FRET acceptors onto the surface of the nanostructures. The general nature of the synthesis, surface addressability, and biocompatibility of the resulting nanostructures offer great promises for nanoelectronics, energy, and biomedical applications.