Tunable Nanoparticles Research Articles

Large, Mesoporous Carbon Nanoparticles with Tunable Architectures for Energy Storage

We report the synthesis of giant carbon particles with spherical and interconnected porous morphologies. Direct organic–organic self-assembly between phenolic resin and polystyrene-block-poly(ethylene oxide) (PS-b-PEO) was employed to prepare these highly ordered carbon particles. Mesoporous carbon nanoparticles with tunable textural characteristics such as large surface area, uniform pore structure, and high thermal properties were achieved by simply adjusting the ratio between the block copolymer to phenol without using acid, base, or activating agents. The synthesized nanoparticles possess a very high surface area of up to 832 m2 g–1, and ultrasmall pore size, as small as 3 nm, and exhibited excellent electrochemical performance when used as active electrodes for lithium-ion batteries. Making use of the secondary interactions between the functional groups of the block copolymer and phenol, this study created tunable nanoparticles with excellent surface area and uniform morphologies that can be used in ...

Surface Chemistry Enhancements for the Tunable Super-Liquid Repellency of Low-Surface-Tension Liquids.

Super-hydrophobic, super-oleo(amphi)phobic, and super-omniphobic materials are universally important in the fields of science and engineering. Despite rapid advancements, gaps of understanding still exist between each distinctive wetting state. The transition of super-hydrophobicity to super-(oleo-, amphi-, and omni-)phobicity typically requires the use of re-entrant features. Today, re-entrant geometry induced super-(amphi- and omni-)phobicity is well-supported by both experiments and theory. However, owing to geometrical complexities, the concept of re-entrant geometry forms a dogma that limits the industrial progress of these unique states of wettability. Moreover, a key fundamental question remains unanswered: are extreme surface chemistry enhancements able to influence super-liquid repellency? Here, this was rigorously tested via an alternative pathway that does not require explicit designer re-entrant features. Highly controllable and tunable vertical network polymerization and functionalization were used to achieve fluoroalkyl densification on nanoparticles. For the first time, relative fluoro-functionalization densities are quantitatively tuned and correlated to super-liquid repellency performance. Step-wise tunable super-amphiphobic nanoparticle films with a Cassie–Baxter state (contact angle of >150° and sliding angle of <10°) against various liquids is demonstrated. This was tested down to very low surface tension liquids to a minimum of ca. 23.8 mN/m. Such findings could eventually lead to the future development of super-(amphi)omniphobic materials that transcend the sole use of re-entrant geometry.

Catalytic evaluation of tunable Ni nanoparticles embedded in organic functionalized 2D and 3D ordered mesoporous silicas from the hydrogenation of nitroarenes

The current drive to explore non-noble metal nanoparticles (NPs) utilized for the hydrogenation of nitroarenes encourages an extensive study of Ni NPs for their affordable price and magnetic properties. However, fabrication of stable and highly dispersed metal NPs against aggregation remains a great challenge. In this study, carboxylic acid modified siliceous supports with two distinctive pore architectures, so called 2D hexagonal channel SBA-15 and 3D cage-type SBA-16 are utilized for the controllable confinement growth of ultra-small Ni NPs. The catalytic activity of Ni-x/SBA-16C is found to be higher than that of Ni-x/SBA-15C and Ni-x/SiO2 in the hydrogenation of nitroarenes to aminoarenes and greatly influenced by the Ni particle size, pore architectures, textural properties and Ni amounts. In addition, the magnetic properties allow facile and rapid recovery of the catalysts for reuse. This approach offers an affordable and easily separable catalyst for industrial applications.

An invisible private 2D barcode design and implementation with tunable fluorescent nanoparticles.

The popularity of 2D barcodes is playing a key role in simplifying people's daily life activities, such as identification, quick payment, checking in and checking out, etc. However, relevant issues have emerged as their popularity has soared. The most urgent and representative problem is decryption, which may lead to serious information leakage and substantial damage to organizations, such as governments and international enterprises. This issue is mainly due to the visibility of 2D barcodes. In order to prevent potential privacy violation and sensitive information leakage through easy access of those visible 2D barcodes, we have designed and fabricated invisible 2D barcodes that will only be visible under UV illumination. This approach provides a promising solution to address the previous problem by transferring 2D barcodes into an invisible state. We have employed a typical micro-emulsion method to fabricate polystyrene (PS) fluorescent nanoparticles due to its simplicity. The invisible patterns can and will only be accessed and recognized under UV light illumination to protect personal private information. These invisible 2D barcodes provide a feasible solution for personal information protection and fit with a patient's privacy protection scenario very well, as we have demonstrated.

Selective hydrogenation of nitroarenes to amines by ligand-assisted Pd nanoparticles: influence of donor ligands on catalytic activity

A simple and facile approach for the synthesis of tunable ligand-assisted Pd nanoparticles for selective hydrogenation of nitroarenes.

Tunable porous silica nanoparticles as a universal dye adsorbent.

Here, we report selective adsorption of cationic dyes methylene blue (MB) and rhodamine B (RB) and anionic dyes methyl orange (MO) and bromo cresol green (BCG) by modifying the surface of cetyl trimethyl ammonium bromide (CTAB) coated porous silica nanoparticles (PSN). We used a top down approach to synthesize PSN (porous silica nanoparticles) without high temperature calcination. X-ray diffraction study confirms the formation of pure phase silica nanoparticles. SEM analysis reveals that the particle morphology is spherical and the size range lies in-between 150–200 nm. We have studied the dye adsorption properties for three cases of PSN at varying calcination temperatures of 100 °C, 250 °C and 500 °C, respectively. Thermal study has been performed in the temperature range of 50–800 °C to check the calcination temperature. In this report, we have tuned the surface properties for selective adsorption of cationic and anionic dyes in water. In the first case, 100 °C calcined PSN selectively adsorb only anionic dyes, whereas in the second case, 500 °C calcined PSN adsorb only cationic dyes and finally, an optimized calcination temperature ≈250 °C could be used for all types of dye to be adsorbed irrespective of charges on the dyes. The mode of interaction of dyes with PSN has been explained with a proper mechanism in all three cases. The adsorptions of dyes are confirmed by UV-Vis spectroscopy. Adsorption capacity and regenerable performance of adsorbents have also been studied.

Shape tunable gallium nanorods mediated tumor enhanced ablation through near-infrared photothermal therapy.

To date, photothermal sensitizers include organic and inorganic nanomaterials for biomedical applications. However, the impediments of low biodegradability and potential toxicity hinder their further applications in clinics. Liquid metal nanospheres show superior photothermal effects under near-infrared laser irradiation, in addition, a transformation in shape can be triggered, which also promotes biodegradability that helps to avoid potential systemic toxicity. Here, we fabricated tunable liquid metal nanoparticles having sphere-shaped to rod-shaped characteristics, resulting in good biocompatibility, favorable photothermal conversion efficiency, and targeting capability to tumors. The synthesis strategy is easy to achieve through one-step sonication. We systematically evaluated the photothermal properties of these liquid metal nanoparticles as well as their destructive effects on tumors in a quantitative way both in vitro and in vivo under laser exposure. Results have shown for the first time in mice that gallium nanorods, regulated and controlled through the production of GaO(OH), displayed outstanding photothermal conversion efficiency and exhibited distinct temperature elevation compared to gallium nanospheres and gallium-indium alloy nanorods. These shape transformable and biocompatible gallium nanorods establish the basis for the future laser ablation of tumors to achieve enhanced therapeutic outcomes. This shape tunability of a smart nano-liquid metal directly contributes to enhanced photothermal therapy in mice and opens new opportunities for potential applications with tumor therapy and imaging.

Metal-Assisted Transfer Strategy for Construction of 2D and 3D Nanostructures on an Elastic Substrate.

Compared with conventional rigid devices, the elastic substrates integrated with functional components offer various advantages, such as flexibility, dynamic tunability, and biocompatibility. However, the reliable formations of 2D nanoparticles, nanogaps, and 3D nanostructures on elastic substrates are still challenging. The conventional transfer method plays an important role in the fabrication of microstructures on elastic substrates; however, it could not fabricate structures with feature size less than a few micrometers. In this article, we have developed a flexible technique based on the "metal-assisted transfer" strategy. The key concept is to introduce a metal film as an assistant layer between nanostructures and silicon substrates to help the fabrication of nanostructures which cannot be successfully transferred in the conventional transfer method. Various 2D nanostructures, which are difficult to achieve on elastic substrates, could be reliably defined using this approach. The desired gap distances and even sub-10 nm metal gaps between adjacent nanoparticles can be controllably achieved. Moreover, 3D nanostructures can be directly assembled from the prestrained 2D precursors based on the developed technique. Comparing with the previous reports, our fabrication method contains only a one-step transfer process without selective bonding or a second transfer process. Significantly, the 3D nanostructures presented here are 2 orders of magnitude smaller than the state-of-the-art mechanically assembled 3D structures in unit cell size. The proposed method may become a mainstream technology for the nano-optics and ultracompact optoelectronic devices due to its multifunctionalities and superior advantages in achieving tunable nanoparticles as well as 3D nanostructures.

Optically induced rotation of Rayleigh particles by arbitrary photonic spin

Optical trapping techniques hold great interest for their advantages that enable direct handling of nanoparticles. In this work, we study the optical trapping effects of a diffraction-limited focal field possessing an arbitrary photonic spin and propose a convenient method to manipulate the movement behavior of the trapped nanoparticles. In order to achieve controllable spin axis orientation and ellipticity of the tightly focused beam in three dimensions, an efficient method to analytically calculate and experimentally generate complex optical fields at the pupil plane of a high numerical aperture lens is developed. By numerically calculating the optical forces and torques of Rayleigh particles with spherical/ellipsoidal shape, we demonstrate that the interactions between the tunable photonic spin and nanoparticles lead to not only 3D trapping but also precise control of the nanoparticles’ movements in terms of stable orientation, rotational orientation, and rotation frequency. This versatile trapping method may open up new avenues for optical trapping and their applications in various scientific fields.

Tunable thermal and electricity generation enabled by spectrally selective absorption nanoparticles for photovoltaic/thermal applications

High-efficiency photovoltaic/thermal systems are being put forward to develop a low-carbon economy. Moreover, nanofluid-based beam splitters with excellent property of selective spectrum absorption have shown great potential to enable effective running of the solar cells and thermal collectors without any interference. In this work, a mathematic model to evaluate the performance of the nanofluid-based beam splitter was established. Ag@TiO2 nanoparticles with selective absorption capability were suspended in water to generate high-efficiency beam splitters for photovoltaic/thermal applications. The nanoparticles exhibited high absorptivity in the visible light wavelengths and good transmittance in the spectral response range of silicon photovoltaic cell. Under the assumption that the relative worth factor was equal to 3, the 200 ppm nanofluid produced ~1.4 times of the overall efficiency compared to water. Furthermore, the merit function reached 2.16 when 100 ppm nanoparticles were suspended owing to high photothermal conversion efficiency of the Ag@TiO2 nanofluid. Moreover, tunable nanoparticle concentrations were adopted to obtain high-efficiency solar energy utilization. Such being the case, differential distributions between electric and thermal energy demands can be realized to match the variable requirements of electricity and heat across geographical differences.

Targeted Photothermal Therapy of Melanoma in C57BL/6 Mice using Fe3O4@Au Core-shell Nanoparticles and Near-infrared Laser.

Background: Gold nanoshells can be tuned to absorb a particular wavelength of light. As a result, these tunable nanoparticles (NPs) can efficiently absorb light and convert it to heat. This phenomenon can be used for cancer treatment known as photothermal therapy. In this study, we synthesized Fe3O4@Au core-shell NPs, magnetically targeted them towards tumor, and used them for photothermal therapy of cancer.Objective: The main purpose of this research was to synthesize Fe3O4@Au core-shell NPs, magnetically target them towards tumor, and use them for photothermal therapy of cancer. Material and Methods: In this experimental study, twenty mice received 2 × 106 B16-F10 melanoma cells subcutaneously. After tumors volume reached 100 mm3, the mice were divided into five groups including a control group, NPs group, laser irradiation group, NPs + laser group and NPs + magnet + laser group. NPs were injected intravenously. After 6 hours, the tumor region was irradiated by laser (808 nm, 2.5 W/cm2, 6 minutes). The tumor volumes were measured every other day. Results: The effective diameter of Fe3O4@Au NPs was approximately 37.8 nm. The average tumor volume in control group, NPs group, laser irradiation group, NPs + laser irradiation group and NPs + magnet + laser irradiation group increased to 47.3, 45.3, 32.8, 19.9 and 7.7 times, respectively in 2 weeks. No obvious change in the average body weight for different groups occurred. Conclusion: Results demonstrated that magnetically targeted nano-photothermal therapy of cancer described in this paper holds great promise for the selective destruction of tumors.

Emulsion Stabilization with Functionalized Cellulose Nanoparticles Fabricated Using Deep Eutectic Solvents.

In this experiment, the influence of the morphology and surface characteristics of cellulosic nanoparticles (i.e., cellulose nanocrystals [CNCs] and cellulose nanofibers [CNFs]) on oil-in-water (o/w) emulsion stabilization was studied using non-modified or functionalized nanoparticles obtained following deep eutectic solvent (DES) pre-treatments. The effect of the oil-to-water ratio (5, 10, and 20 wt.-% (weight percent) of oil), the type of nanoparticle, and the concentration of the particles (0.05–0.2 wt.-%) on the oil-droplet size (using laser diffractometry), o/w emulsion stability (via analytical centrifugation), and stabilization mechanisms (using field emission scanning electron microscopy with the model compound—i.e., polymerized styrene in water emulsions) were examined. All the cellulosic nanoparticles studied decreased the oil droplet size in emulsion (sizes varied from 22.5 µm to 8.9 µm, depending on the nanoparticle used). Efficient o/w emulsion stabilization against coalescence and an oil droplet-stabilizing web-like structure were obtained only, however, with surface-functionalized CNFs, which had a moderate hydrophilicity level. CNFs without surface functionalization did not prevent either the coalescence or the creaming of emulsions, probably due to the natural hydrophobicity of the nanoparticles and their instability in water. Moderately hydrophilic CNCs, on the other hand, distributed evenly and displayed good interaction with both dispersion phases. The rigid structure of CNCs meant, however, that voluminous web structures were not formed on the surface of oil droplets; they formed in flat, uniform layers instead. Consequently, emulsion stability was lower with CNCs, when compared with surface-functionalized CNFs. Tunable cellulose nanoparticles can be used in several applications such as in enhanced marine oil response.

Facile Synthesis of Cellulose/ZnO Aerogel with Uniform and Tunable Nanoparticles Based on Ionic Liquid and Polyhydric Alcohol

Cellulose/zinc oxide (ZnO) aerogels are traditionally produced using methods harmful to the environment because of the acids and alkalis that are involved in the production process. This study repo...

Significant enhancement of direct electric communication across enzyme-electrode interface via nano-patterning of synthetic glucose dehydrogenase on spatially tunable gold nanoparticle (AuNP)-modified electrode

In this study, the effect of inter-enzyme steric hindrance that occurs during enzyme immobilization on the electrode, on direct electrical communications of enzyme with electrode was investigated via nano-patterning of enzymes on the electrode. Here, the nano-patterning of enzymes was achieved through the combination of DET-capable enzyme that was produced via fusion of site-specific gold binding peptide (GBP) to catalytic subunit of enzyme and gold nanoparticle (AuNP) array with highly tunable dimensions of AuNPs, resulting in spatially controllable enzyme-electrode. The nano-scale spatial control between immobilized enzymes on the highly tuned AuNPs shows different DET efficiency across the enzyme-electrode interface, showing 18.47% of maximum electron recovery which is 3.2-fold enhanced electron recovery efficiency compared to spatially non-controlled enzymes on the electrode where showed 5.7% of electron recovery. The result affirms that inter-enzyme interaction is a significant parameter that decides the enzyme-electrode performance.

Tunable Aggregation-Induced Emission Nanoparticles by Varying Isolation Groups in Perylene Diimide Derivatives and Application in Three-Photon Fluorescence Bioimaging.

The development of fluorogens with deep-red emission is one of the hottest topics of investigation in the field of bio/chemosensors and bioimaging. Herein, the tunable fluorescence of perylene diimide (PDI) derivatives was achieved by the incorporation of varied isolation groups linked on the PDI core. With the enlarged sizes of isolation groups, the conversion from aggregation caused quenching to aggregation-induced emission was obtained in their fluorescence variations from solutions to nanoparticles, as the result of the efficient inhibition of π-π stacking by the larger isolation groups. Accordingly, DCzPDI bearing 1,3-di(9H-carbazol-9-yl)benzene as the biggest isolation group exhibited the bright deep-red emission in the aggregated state with a quantum yield of 12.3%. Combined with the three-photon excited fluorescence microscopy (3PFM) technology, through-skull 3PFM imaging of mouse cerebral vasculature can be realized by DCzPDI nanoparticles with good biocompatibility, and the penetration depth can be as deep as 450 μm.

A green synthetic approach for size tunable nanoporous gold nanoparticles and its glucose sensing application

A novel approach for environmentally benign green synthesis of zero-dimensional monodispersed nanoporous gold nanoparticles (npGNPs) with tunable size has been developed. It involves the use of Oryza sativa seeds (Asian rice) extract as a reducing agent for the simultaneous bio-reduction of gold (Au3+) and silver (Ag+) ions to form alloys nanoprecursor that led to the formation of npGNPs using Au (I) as an oxidative etchant in galvanic replacement reaction. In comparison to conventional methods, no harsh reaction conditions were used during the synthesis to comply with the green chemistry. The synthesized npGNPs were characterized using transmission electron microscopy (TEM), field emission-scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV–visible spectroscopy. Monodispersed nanoporous gold nanoparticles in the size range of 80–150 nm were obtained as confirmed by electron microscopy. The size can easily be tuned by varying the concentration of silver precursor. The synthesized nanoporous gold nanoparticles were then evaluated for their electrocatalytic activity toward non-enzymatic glucose sensing by cyclic voltammetry (CV) and linear scan voltammetry (LSV). In a comparative study with bare Au electrode and Au-Ag nanoparticles modified electrode, the resulting npGNPs modified sensor exhibited a better response toward glucose in the linear range from 1 to 50 μM with a sensitivity of 6.67 µA µM−1 cm2.

Understanding the Interplay between Self-Assembling Peptides and Solution Ions for Tunable Protein Nanoparticle Formation.

Protein-based nanomaterials are gaining importance in biomedical and biosensor applications where tunability of the protein particle size is highly desirable. Rationally designed proteins and peptides offer control over molecular interactions between monomeric protein units to modulate their self-assembly and thus particle formation. Here, using an example enzyme-peptide system produced as a single construct by bacterial expression, we explore how solution conditions affect the formation and size of protein nanoparticles. We found two independent routes to particle formation, one facilitated by charge interactions between protein-peptide and peptide-peptide exemplified by pH change or the presence of NO3- or NH4+ and the second route via metal-ion coordination ( e.g., Mg2+) within peptides. We further demonstrate that the two independent factors of pH and Mg2+ ions can be combined to regulate nanoparticle size. Charge interactions between protein-peptide monomers play a key role in either promoting or suppressing protein assembly; the intermolecular contact points within protein-peptide monomers involved in nanoparticle formation were identified by chemical cross-linking mass spectrometry. Importantly, the protein nanoparticles retain their catalytic activities, suggesting that their native structures are unaffected. Once formed, protein nanoparticles remain stable over long periods of storage or with changed solution conditions. Nevertheless, formation of nanoparticles is also reversible-they can be disassembled by desalting the buffer to remove complexing agents ( e.g., Mg2+). This study defines the factors controlling formation of protein nanoparticles driven by self-assembly peptides and an understanding of complex ion-peptide interactions involved within, offering a convenient approach to tailor protein nanoparticles without changing amino acid sequence.

An Efficient Co/C Microwave Absorber with Tunable Co Nanoparticles Derived from a ZnCo Bimetallic Zeolitic Imidazolate Framework

AbstractA facile strategy is developed to modulate the content, particle size, and dispersity of magnetic metal nanoparticles (NPs) in porous carbon composite derived from Co/Zn bimetallic zeolitic imidazolate framework (ZIF). By adjusting the Co/Zn mole ratio in ZIF structure, porous carbon embedded with controllable Co NPs is synthesized through pyrolysis of CoZn‐based ZIF during which Zn is selectively evaporated away at 900 °C. The Co/C composite derived from ZIF with Co/Zn ratio of 1/1 (Co50/C composite) displays well‐dispersed Co NPs uniformly embedded in porous carbon. Meanwhile, the impedance matching of the composite is significantly improved due to the appropriate amount of Co NPs. Benefiting from the synergistic effect between Co NPs with magnetic loss and carbon with dielectric loss, the Co50/C composite exhibits excellent microwave absorbing properties with strong absorption, thin thickness, and lightweight, which is superior to previous metal–organic framework‐derived absorbers. When the filler loading of Co50/C composite in paraffin matrix is only 20 wt%, a minimum reflection loss of −51.6 dB is achieved at a very thin layer thickness of 1.6 mm.

Engineering Tunable Dual Functional Protein Cage Nanoparticles Using Bacterial Superglue.

The selective detection of specific cells of interest and their effective visualization is important but challenging, and fluorescent cell imaging with target-specific probes is commonly used to visualize cell morphology and components and to track cellular processes. Multiple displays of two or more targeting ligands on a polyvalent single template would make it possible to construct versatile multiplex fluorescent cell imaging probes that can visualize two or more target cells individually without the need for a set of individual probes. To achieve this goal, we used encapsulin, a new class of protein cage nanoparticles, as a template and implanted dual targeting capability by presenting two different affibody molecules on a single encapsulin protein cage nanoparticle post-translationally. Encapsulin was self-assembled from 60 identical subunits to form a hollow and symmetric spherical structure with a uniform size. We genetically inserted SpyTag peptides onto the encapsulin surface and prepared various SpyCatcher-fused proteins, such as fluorescent proteins and targeting affibody molecules. We successfully displayed fluorescent proteins and affibody molecules together on a single encapsulin in a mix-and-match manner post-translationally using bacterial superglue, the SpyTag/SpyCatcher ligation system, and demonstrated that these dual functional encapsulins can be used as target-specific fluorescent cell imaging probes. Dual targeting protein cage nanoparticles were further constructed by ligating two different affibody molecules onto the encapsulin surface with fluorescent dyes, and they effectively recognized and bound to two individual targeting cells independently, which could be visualized by selective colors on demand.

Fabrication of Ag@TiO2 electrospinning nanofibrous felts as SERS substrate for direct and sensitive bacterial detection

In order to develop a novel method for bacteria detection, Ag@TiO2 electrospinning Nanofibrous felts have been fabricated by in situ decoration of size tunable Ag nanoparticles on anatase TiO2 nanofibers. The morphologies and structures of the as-prepared Ag@TiO2 electrospinning nanofibrous felts were characterized by techniques of scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction. The result show that Ag NPs were uniformly deposited on the surfaces of TiO2 nanofibers, especially when the deposition time in Tollens’ reagent was 10 min. The free-standing composite nanofibrous felts processes superb performance of surface enhanced Raman scattering, which was demonstrated by small probe mecules of 4-mercaptobenzoic acid and 4-mercaptophenol, and the lowest detection limit was near to10−9 mol/L. More importantly, the as-fabricated Ag@TiO2 nanofibrous felts as SERS substrate can detect biomacromolecules such as bacteria of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) directly without previous bacteria-aptamer conjugation as the traditonal process. In addition, the composite nanofibrous felts also show outstanding antimicrobial activities against both Gram-negative of E. coli and Gram-positive of S. aureus, evaluated by method of absorption and microscopic observation. The results show that the bacteriostasis rate is reached to 99%, especially significant for E. coli. The free-standing, high porous, and flexible substrate of Ag@TiO2 electrospun nanofibrous membranes have potential application in versatile fields such as microorganism sensors and water purifier.