In order to mimic cell organelles, artificial nanoreactors have been investigated based on polymeric vesicles with reconstituted channel proteins (outer membrane protein F) and coencapsulated enzymes horseradish peroxidase (HRP) along with a crowding agent (Ficoll or polyethylene glycol) inside the cavity. Importantly, the presence of macromolecules has a strong impact on the enzyme kinetics, but no influence on the integrity of vesicles up to certain concentrations. This particular design allows for the first time the determination of HRP kinetics inside nanoreactors with crowded milieu. The values of the Michaelis Menten constant (K-m) measured for HRP in a confined space (encapsulated in nanoreactors) in the absence of macromolecules are approximate to 50% lower than in free conditions, and the presence of a crowding agent results in a further pronounced decrease. These results clearly suggest that activities of enzymes in confined spaces can be tuned by varying the concentrations of crowding compounds. The present investigation represents an advance in nanoreactor design by considering the influence of environmental factors on enzymatic performance, and it demonstrates that both encapsulation and the presence of a crowding environment increase the enzyme-substrate affinity.
Spatial arrangement of 1D nanomcrterials may offer enormous opportunities for advanced electronics and photonics. Moreover, morphological complexity and chemical diversity in the nanoscale components may lead to unique properties that are hardly anticipated in randomly distributed homogeneous nanostructures. Here, controlled chemical segmentation of metal nanowire arrays using block copolymer lithography and subsequent reversible metal ion loading are demonstrated. To impose chemical heterogeneity in the nanowires generated by block copolymer lithography, reversible ion. loading method highly specific for one particular polymer block is introduced. Reversibility of the metal ion loading enables area-selective localized replacement of metal ions in the self-assembled patterns and creates segmented metal nanowire arrays with different metallic components. Further integration of this method with shear aligning process produces high aligned segmented metal nanowire array with desired local chemical compositions.
A novel SMART module, dubbed "DNA-SMART" (DNA substrate modification and replication by thermoforming) is reported, where polymer films are premodified with single-stranded DNA capture strands, microthermo formed into 3L) structures, and postmodified with complementary DNA-protein conjugates to realize complex biologically active surfaces within microfluidic devices. As a proof of feasibility, it is demonstrated that microchannels presenting three different proteins on their inner curvilinear surface can be used for selective capture of cells under flow conditions.
There is an urgent need to develop metal-free, low cost, durable, and highly efficient catalysts for industrially important oxygen evolution reactions. Inspired by natural geodes, unique melamine nanogeodes are successfully synthesized using hydrothermal process. Sulfur-modified graphitic carbon nitride (S-modified g-CA(x)) electrocatalysts are obtained by annealing these melamine nanogeodes in situ with sulfur. The sulfur modification in the g-CNx structure leads to excellent oxygen evolution reaction activity by lowering the overpotential. Compared with the previously reported nonmetallic systems and well-established metallic catalysts, the S-modified g-CNx nanostructures show superior performance, requiring a lower overpotential (290 mV) to achieve a current density of 10 mA cm(-2) and a Tafel slope of 120 mV dec(-1) with long-term durability of 91.2% retention for 18 h. These inexpensive, environmentally friendly, and easy-to-synthesize catalysts with extraordinary performance will have a high impact in the field of oxygen evolution reaction electrocatalysis.
The combination of complementary techniques to characterize materials at the nanoscale is crucial to gain a more complete picture of their structure, a key step to design and fabricate new materials with improved properties and diverse functions. Here it is shown that correlative atomic force microscopy (AFM) and localization based super-resolution microscopy is a useful tool that provides insight into the structure and emissive properties of fluorescent beta-lactoglobulin (beta LG) amyloid-like fibrils. These hybrid materials are made by functionalization of beta LG with organic fluorophores and quantum dots, the latter being relevant for the production of 11) inorganic nanostructures templated by self-assembling peptides. Simultaneous functionalization of beta LG fibers by QD655 and QD525 allows for correlative AFM and two-color super-resolution fluorescence imaging of these hybrid materials. These experiments allow the combination of information about the topography and number of filaments that compose a fibril, as well as the emissive properties and nanoscale spatial distribution of the attached fluorophores. This study represents an important step forward in the characterization of multifunctionalized hybrid materials, a key challenge in nanoscience.
Gene therapies enable therapeutic interventions at gene transcription and translation level, providing enormous potential to improve standards of care for multiple diseases. Nonviral transfection agents and in particular polyplexes based on block ionomers are besides viral vectors and cationic lipid formulations among the most promising systems for this purpose. Block ionomers combine a hydrophilic noncharged block, e.g., polyethylene glycol (PEG), with a hydrophilic cationic block. For efficient transfection, however, endosomolytic moieties, e.g., imidazoles, are additionally required to facilitate endosomal escape, which raises the general question how to distribute these functionalities within the block copolymer. Combining molecular dynamics simulation with physicochemical and biological characterization, this work aims to provide a first rational for the influence of block ionomer microstructure on polyplex properties, e.g., size, shape, and transfection efficiency. Our findings underline that a triblock microstructure is most efficient in compacting pDNA, which reduces polyplex size, enhances stability against degradation by DNase I; and thus provides better transfection performance.
Microstructures with 3D features provide advanced functionalities in many applications. Reaction-diffusion process has been employed in photolithography oduce pseudo-3D microstructures in a reproducible manner. In this work, the influences of various parameters on growth behavior of polymeric structures are investigated and the use of the reaction-diffusion-mediated photolithography (RDP) is expanded to a wide range of structural dimensions. In addition, how a lens effect alters the growth behavior of microstructures in conjunction with reaction-diffusion process is studied. For small separation between reaction sites in the array, ultraviolet (UV) exposure time is optimized along with the separation to avoid film or plateau formation. It is further proved that the RDP process is highly reproducible and applicable to various photocurable resins. In a demonstrative purpose, the use of microdomes created by the RDP process as microlens arrays is shown. The RDP process enables the production of pseudo-3D microstructures even with collimated UV light in the absence of complex optical setups, thereby potentially serving as a useful means to create micropauerns and particles with unique structural features.
Hierarchical C-60 colloidal films are assembled from nanoscale to macroscale. Fullerene molecular crystals are grown via seeded cosolvent precipitation with mixed solvent Petrahydronaphthalene (THN)/trimethylpyridine ( TMP)] and antisolvent 2-propanol. The fullerene solutions are aged under illumination, which due to the presence of TMP reduces the free monomer concentration through fullerene aggregation into nanoparticles. The nanoparticles seed the growth of monodisperse fullerene colloids on injection into the antisolvent. Diverse colloidal morphologies are prepared as a function of injection volume and fullerene solution concentration. The high fullerene solubility of TUN enables C-60 colloids to be prepared in quantities sufficient for assembly (5 x 10(8)). Electric fields are applied to colloidal C-60 platelets confined to two dimensions. The particles assemble under dipolar forces, dielectrophoretic forces, and electrohydrodynamic flows. Frequency-dependent phase transitions occur at the critical Maxwell Wagner crossover frequency, where the effective polarizability of the particles in the medium is substantially reduced. Structures form as a function of field strength, frequency, and confinement including hexagonal, oblique, string fluid, coexistent hexagonal-rhombic, and tetratic.
Novel amorphous vanadium oxide coated copper vanadium, oxide (Cu11V6O26/V2O5) microspheres with 3D hierarchical architecture have been successfully prepared via a microwave-assisted solution method and subsequent annealing induced phase separation process. Pure Cu11V6O26 microspheres without V2O5; coating are also obtained by an H2O2 solution dissolving treatment. When evaluated as an anode material for lithium-ion batteries (LIBs), the as-synthesized hybrid exhibits large reversible capacity, excellent rate capability, and outstanding capacity self recovery. Under the condition of high current density of 1 A g(-1), the 3D hierarchical Cu11V6O26/V2O5 hybrid maintains a reversible capacity of approximate to 1110 mA h g(-1). Combined electrochemical analysis and high-resolution transmission electron microscopy observation during cycling reveals that the amorphous V2O5; coating plays an important role on enhancing the electrochemical performances and capacity self recovery, which provides an active amorphous protective layer and abundant grain inter faces for efficient inserting and extracting of Li-ion. As a result, this new copper vanadium oxide hybrid is proposed as a promising anode material for LIBs.
Imaging-guided therapy systems (IGTSs) are revolutionary techniques used in cancer treatment due to their safety and efficiency. IGTSs should have tunable compositions for bioimaging, a suitable size and shape for biotransfer, sufficient channels and/or pores for drug loading, and intrinsic hiocompatibility. Here, a hiocompatible nanoscale zirconium-porphyrin metal organic framework (NPMOF)-based IGTS that is prepared using a microemulsion strategy and carefully tuned reaction conditions is reported. A high content of porphyrin (59.8%) allows the achievement of efficient fluorescent imaging and photodynamic therapy (PDT). The ID channel of the Kagome topology of NPMOFs provides a 109% doxorubicin loading and pH-response smart release for chemotherapy. The fluorescence guiding of the chemotherapy-and-PDT dual system is confirmed by the concentration of NPMOFs at cancer sites after irradiation with a laser and doxorubicin release, while low toxicity is observed in normal tissues. NPMOFs are established as a promising platform for the early diagnosis of cancer and initial therapy.
Nanohybrids composed of two or more components exhibit many distinct physicochemical properties and hold great promise for applications in optics, electronics, magnetics, new energy, environment protection, and biomedical engineering. Microfluidic systems exhibit many advantages due to their unique characteristics of narrow channels, variable length, controllable number of channels and multiple integrations. Particularly their spatial-temporarily splitting of the formation stages during nanomaterials formation along the microfluidic channels favors the online control of the reaction kinetic parameters and in situ tuning of the product properties. This Review is focused on the features of the current types of microfluidic devices in the synthesis of different types of nanohybrids based on the classification of the four main kinds of materials: metal, nonmetal inorganic, polymer and composites. Their morphologies, compositions and properties can be adjusted conveniently in these synthesis systems. Synthesis advantages of varieties of microfluidic devices for specific nanohybrids of defined surfaces and interfaces are presented according to their process and microstructure features of devices as compared with conventional methods. A summary is presented, and challenges are put forward for the future development of the microfluidic synthesis of nanohybrids for advanced applications.
Atomically thin hexagonal boron nitride (h-BN) is gaining significant attention for many applications such as a dielectric layer or substrate for graphene-based devices. For these applications, synthesis of high-quality and large-area h-BN layers with few defects is strongly desirable. In this work, the aligned growth of millimeter-size single-crystal h-BN domains on epitaxial Ni (111)/sapphire substrates by ion beam sputtering deposition is demonstrated. Under the optimized growth conditions, single-crystal h-BN domains up to 0.6 mm in edge length are obtained, the largest reported to date. The formation of large-size h-BN domains results mainly from the reduced Ni-grain boundaries and the improved crystallinity of Ni film. Furthermore, the h-BN domains show well-aligned orientation and excellent dielectric properties. In addition, the sapphire substrates can be repeatedly used with almost no limit. This work provides an effective approach for synthesizing large-scale high-quality h-BN layers for electronic applications.
A continuing trend of miniaturized and flexible electronics/optoelectronic calls for novel device architectures made by compatible fabrication techniques. However, traditional layer-to-layer structures cannot satisfy such a need. Herein, a novel monolithic optoelectronic device fabricated by a mask-free laser direct writing method is demonstrated in which in situ laser induced graphene-like materials are employed as lateral electrodes for flexible ZnS/SnO2 ultraviolet photodetectors. Specifically, a ZnS/SnO2 thin film comprised of heterogeneous ZnS/SnO2 nanoparticles is first coated on polyimide (PI) sheets by a solution process. Then, CO2 laser irradiation ablates designed areas of the ZnS/SnO2 thin film and converts the underneath PI into highly conductive graphene as the lateral electrodes for the monolithic photodetectors. This in situ growth method provides good interfaces between the graphene electrodes and the semiconducting ZnS/SnO2 resulting in high optoelectronic performance. The lateral electrode structure reduces total thickness of the devices, thus minimizing the strain and improving flexibility of the photodetectors. The demonstrated lithography-free monolithic fabrication is a simple and cost-effective method, showing a great potential for developement into roll-to-roll manufacturing of flexible electronics.
An effective colloidal process involving the hot-injection method is developed to synthesize uniform nanoflowers consisting of 2D gamma-In2Se3 nanosheets. By exploiting the narrow direct bandgap and high absorption coefficient in the visible light range of In2Se3, a high-quality gamma-In2Se3/Si heterojunction photodiode is fabricated. This photodiode shows a high photoresponse under light illumination, short response/ recovery times, and long-term durability. In addition, the gamma-In2Se3/Si heterojunction photodiode is self-powered and displays a broadband spectral response ranging from UV to IR with a high responsivity and detectivity. These excellent performances make the gamma-In2Se3/Si heterojunction very interesting as highly efficient photodetectors.
The nanoplatform GNR-ACPP-PpIX (designated as GNR-ACPI) is designed for dual image guided combined activatable photodynamic therapy (PDT) and photothermal therapy (PTT). In GNR-ACPI, gold nanorods (GNRs) are modified with a protoporphyrin (PpIX, a PDT agent) conjugated activatable cell penetrating peptide (ACPP), which consists of the matrix metalloproteinases-2 (MMP-2) sensitive peptide sequence GPLGLAG. First, the photoactivity of PpIX is effectively quenched by GNRs due to the strong near infrared region light absorption of GNR and the special "U type" structure of ACPP induced close contact between PpIX and GNR. However, once arriving at the tumor site, the GPLGLAG sequence is hydrolyzed by the MMP-2 overexpressed by tumor cells, resulting in the release of the residual cell membrane penetrating peptide (CPP) attached PpIX (CPP-PpIX) with the recovery of photoactivity of PpIX. In addition, with the help of CPP, more efficient cellular uptake of PpIX by tumor cells can be achieved, which will greatly improve the PDT efficacy. Moreover, the GNR can also be utilized for photothermic imaging as well as PTT for tumors. It is found that the combination of PTT and PDT under the guidance of dual-mode imaging greatly enhances the antitumor effects, while possessing negligible systematic toxicity.
Understanding the fundamental biophysics behind protein-nanoparticle (NP) interactions is essential for the design and engineering bio-NP systems. The authors describe the development of a coarse-grained protein-NP model that utilizes a structure centric protein model. A key feature of the protein-NP model is the quantitative inclusion of the hydrophobic character of residues in the protein and their interactions with the NP surface. In addition, the curvature of the NP is taken into account, capturing the protein behavior on NPs of different size. The authors evaluate this model by comparison with experimental results for structure and adsorption of a model protein interacting with an NP. It is demonstrated that the simulation results recapitulate the structure of the small alpha/beta protein GB1 on the NP for data from circular dichroism and fluorescence spectroscopy. In addition, the calculated protein adsorption free energy agrees well with the experimental value. The authors predict the dependence of protein folding on the NP size, surface chemistry, and temperature. The model has the potential to guide NP design efforts by predicting protein behavior on NP surfaces with various chemical properties and curvatures.
Efficient delivery of genes and therapeutic agents to the interior of the cell is critical for modern biotechnology. Herein, a new type of chemical-free cell poration method--hypersonic poration-is developed to improve the cellular uptake, especially the nucleus uptake. The hypersound (approximate to GHz) is generated by a designed piezoelectric nano-electromechanical resonator, which directly induces normal/shear stress and "molecular bombardment" effects on the bilayer membranes, and creates reversible temporal nanopores improving the membrane permeability. Both theory analysis and cellular uptake experiments of exogenous compounds prove the high delivery efficiency of hypersonic poration. Since target molecules in cells are accumulated with the treatment, the delivered amount can be controlled by tuning the treatment time. Furthermore, owing to the intrinsic miniature of the resonator, localized drug delivery at a confined spatial location and tunable arrays of the resonators that are compatible with multiwell plate can be achieved. The hypersonic poration method shows great delivery efficacy combined with advantage of scalability, tunable throughput, and simplification in operation and provides a potentially powerful strategy in the field of molecule delivery, cell transfection, and gene therapy.