Preparation Of Nanomaterials Research Articles

Integrated Cu–Au stereo microelectrode arrays and microfluidic channels for the electrochemical detection of glucose

Noble and transition metal nanomaterials are widely used in glucose sensing. However, the fabrication of these sensors still suffers from complex nanomaterial synthesis process and unstable nanomaterial loading on sensing surfaces. Herein, a Cu–Au bimetallic microelectrode array was prepared via local electrochemical deposition and electrochemical reduction without the need for templates and additional nanomaterial preparation processes. Based on the COMSOL computational fluid study, the obtained microelectrode arrays combined with microfluidic channels allow the continuous and rapid detection of glucose. Large number of active sites on the surface of 3D nano-arrays contributes to excellent sensing performance for glucose, with good linear detection ranges in 10 µM to 4 × 102 µM and 4 × 102 µM to 4 × 105 µM, and a low detection limit of 284 nM. The feasibility of sensor in real sample was verified by detecting glucose in beverages with good recoveries ranging from 95.50% to 104.31%.

Experimental study on the characteristics of V‐type arc plasma torch with four electrodes

AbstractThe arc plasma is widely used in various fields due to its excellent advantages, such as elevated temperature, high enthalpy, and increased energy density. Under this direction, a four‐electrode V‐shaped arc plasma torch was developed to increase both the arc power and plasma volume. The arc dynamic characteristics, the volt‐ampere characteristics, and the thermal efficiency of the arc plasma torch were systematically studied. From the acquired results, a large‐scale, and low‐frequency re‐strike process between the arc channels was demonstrated. Compared with the common twin‐electrode structure, the stability of the four‐electrode structure during the discharging process was improved, exhibiting a wider frequency distribution of the re‐strike events. The electrode layout may also affect the dynamic evolution process of the arc. However, from a statistical point of view, no significant differences in electrical characteristics were recorded. The four‐electrode V‐shaped arc plasma torch presented a typical descending volt‐ampere characteristic, and the re‐strike frequency increased with an increase in the current. A high thermal efficiency (above 83%) was obtained in the range of arc current of 80–200 A. At a current value of 200 A, the jet enthalpy and the average gas temperature can reach 17.41 MJ/kg and 6590 K, and the corresponding jet length was close to 80 cm because of both the high thermal efficiency and enthalpy. The stable discharge process, high thermal efficiency, high jet enthalpy value, and large volume rendered the proposed four‐electrode V‐shaped arc plasma torch to be suitable for various applications including nanomaterial preparation, metal powder spheroidization, etc.

Multifunctional gold nanorod composite for NIR imaging and photodynamic therapy treatment of tumor

The preparation of an effective functional nanomaterial that combines near-infrared imaging and photodynamic therapy functions remains a highly challenging task. The unique tunable optical properties of gold nanorods in the near-infrared region compensate for the limitations of traditional fluorescent dyes and other metal nanoparticles in biological imaging applications. Gold nanorods play a crucial role in biological tissue imaging, early cancer diagnosis and therapy. In this paper, we got gold nanorods in different aspect ratio by adjusting the content of AgNO3 in the growth solution. Subsequently, we developed a novel multi-functional delivery system (5-ALA-loaded GNRs@SiO2@PHIS) using GNRs as cores. The nanocomposite was loaded with a photosensitizer called 5-Aminolevulinic acid (ALA) and conjugated with a pH-sensitive polymer called poly-histidine (PHIS). The PHIS can induce pH-triggered drug release and facilitate endo/lysosome escape, thereby enhancing drug efficacy. The current study on in vitro experiments indicated that the multifunctional gold nanorod composite exhibit strong light scattering in the near-infrared region and effectively induced cancer cell through photodynamic therapy treatment. Overall, this study presents an innovative strategy for the development of versatile photodynamic therapy for cancer theranostics.

Multimorphological Remoldable Silver Nanomaterials from Multimode and Multianalyte Colorimetric Sensing to Molecular Information Technology.

Inspired by life's interaction networks, ongoing efforts are to increase complexity and responsiveness of multicomponent interactions in the system for sensing, programmable control, or information processing. Although exquisite preparation of single uniform-morphology nanomaterials has been extremely explored, the potential value of facile and one-pot preparation of multimorphology nanomaterials has been seriously ignored. Here, multimorphological silver nanomaterials (M-AgN) prepared by one pot can form interaction networks with various analytes, which can be successfully realized from multimode and multianalyte colorimetric sensing to molecular information technology (logic computing and security). The interaction of M-AgN with multianalytes not only induces multisignal responses (including color, absorbance, and wavelength shift) for sensing metal ions (Cr3+, Hg2+, and Ni2+) but also can controllably reshape its four morphologies (nanodots, nanoparticles, nanorods, and nanotriangles). By abstracting binary relationships between analytes and response signals, multicoding parallel logic operations (including simple logic gates and cascaded circuits) can be performed. In addition, taking advantage of natural concealment and molecular response characteristics of M-AgN nanosystems can also realize molecular information encoding, encryption, and hiding. This research not only promotes the construction and application of multinano interaction systems based on multimorphology and multicomponent nanoset but also provides a new imagination for the integration of sensing, logic, and informatization.

Size dependence of the phase transition temperature of metal nanocrystals

Melting, freezing, and evaporation are common phase transition processes in metallic nanocrystals. Predicting these phase transitions and understanding their underlying mechanisms are crucial for the design, preparation, and application of nanomaterials. In this work, we establish the thermodynamic models to describe the size dependence of cohesive energy Ec, melting temperature Tm, freezing temperature Tf, and evaporation temperature Te. By comparing the predictions with the available experimental results, a good agreement is obtained. In addition, we find that at the same diameter D, the Tm(D)/Tm, Tf(D)/Tf, and Te(D)/Te of nanocrystals increase with the improvement of the ratio of solid-liquid interface energy γsl to interfacial stress f, indicating that γsl/f determines the thermal stability of the surfaces.

Biocompatible protein nanogels as robust signal labels for persistent chemiluminescence immunoassays

Nanostructured materials with elegant properties have promising potentials in chemiluminescence (CL) immunoassay. However, the robust preparation of such nanomaterials is still challenging. In this work, biocompatible and easily prepared gelatin/horseradish peroxidase (Gel/HRP) nanogels were exploited as signal labels for chemiluminescence immunoassays. The catalytic property of HRP was well retained and the stability was improved after the incorporation into nanogels. The prepared protein nanogels show enhanced and glow-type luminescence behaviors in luminol-H2O2 CL system. Persistent and sensitive CL immunoassay for CEA were constructed using Gel/HRP nanogels as signal labels. A wide linear response range from 0.01 to 100 ng/mL was obtained with the limit of detection was 3.39 pg/mL (S/N = 3).

Synthesis of Au-Ag bimetallic nanoparticles using Korean red ginseng (Panax ginseng Meyer) root extract for chemo-photothermal anticancer therapy.

Green synthesis strategies have been widely applied for the preparation of versatile nanomaterials. Gold nanospheres with an average size of 6.95 ± 2.25nm were green synthesized by using a 70% ethanol extract of Korean red ginseng (Panax ginseng Meyer) root as a reducing agent. A seed-mediated synthesis was conducted to prepare Au-Agbimetallic nanoparticles using gold nanospheres as seeds. Remarkably, Au-Ag bimetallic nanoparticles with an average size of 80.4 ± 11.9nm were synthesized. Scanning transmission electron microscopy, energy dispersive X-ray spectroscopy and elemental mappings revealed bimetallic nanoparticles with Au-Ag alloy core and Au-rich shells. A face-centered cubic structure of Au-Ag bimetallic nanoparticles was confirmed by X-ray diffraction analysis. For Au-Ag bimetallic nanoparticles, the ratio of Ag/Au was 0.20 which was detected and analyzed by inductively coupled plasma-mass spectrometry. Gold nanospheres and Au-Ag bimetallic nanoparticles were functionalized by PEGylation, folic acid conjugation and grafting onto graphene oxide. Finally, docetaxel was loaded for evaluating the in vitro cell viability on cancer cells. Successful functionalization was confirmed by Fourier-transform infrared spectra. The anticancer activity of the docetaxel-loaded nanoparticles was higher than that of their non-docetaxel-loaded counterparts. The highest anticancer activity on human gastric adenocarcinoma cells (AGS) was observed in the docetaxel-loaded gold nanospheres that were functionalized by PEGylation, folic acid conjugation and grafting onto graphene oxide. Additionally, grafting onto graphene oxide and docetaxel loading induced high intracellular reactive oxygen species generation. For chemo-photothermal (PTT) anticancer therapy, cell viability was investigated using near-infrared laser irradiation at 808nm. The highest chemo-PTT anticancer activity on AGS cells was observed in the docetaxel-loaded Au-Ag bimetallic nanoparticles. Therefore, the newly prepared docetaxel-loaded Au-Ag bimetallic nanoparticles in the current report have potential applications in chemo-PTT anticancer therapy.

Metal-Organic Frameworks Meet Polymers: From Synthesis Strategies to Healthcare Applications.

Metal-organic frameworks (MOFs) have been at the forefront of nanotechnological research for the past decade owing to their high porosity, high surface area, diverse configurations, and controllable chemical structures. They are a rapidly developing class of nanomaterials that are predominantly applied in batteries, supercapacitors, electrocatalysis, photocatalysis, sensors, drug delivery, gas separation, adsorption, and storage. However, the limited functions and unsatisfactory performance of MOFs resulting from their low chemical and mechanical stability hamper further development. Hybridizing MOFs with polymers is an excellent solution to these problems, because polymers-which are soft, flexible, malleable, and processable-can induce unique properties in the hybrids based on those of the two disparate components while retaining their individuality. This review highlights recent advances in the preparation of MOF-polymer nanomaterials. Furthermore, several applications wherein the incorporation of polymers enhances the MOF performance are discussed, such as anticancer therapy, bacterial elimination, imaging, therapeutics, protection from oxidative stress and inflammation, and environmental remediation. Finally, insights from the focus of existing research and design principles for mitigating future challenges are presented.

Application of self-assembly technology in the field of medicine

In recent years, the preparation of polymer micelles and self-assembled nanomaterials by amphiphilic block copolymers has attracted great interest and has now become a research hotspot in the field of polymer science. Based on the self-assembly technology of block compounds, this paper introduces how self-assembly technology can play a role in the clinical environment, especially for the treatment of tumors and cancer, and controlled drug release. Finally, the related challenges and opportunities for self-assembled nanoparticles are described and prospected. Currently, although block copolymers have great performance in many fields, it is difficult to summarize one or a series of regular methods for the preparation of block copolymers and we also did not find a preparation method suitable for industrial production and wide application.

Anticancer Activity of Au/CNT Nanocomposite Fabricated by Nanosecond Pulsed Laser Ablation Method on Colon and Cervical Cancer.

Gold nanoparticles (AuNPs) and carbon nanotubes (CNTs) are increasingly being investigated for cancer management due to their physicochemical properties, low toxicity, and biocompatibility. This study used an eco-friendly technique (laser synthesis) to fabricate AuNP and Au/CNT nanocomposites. AuNPs, Au/CNTs, and CNTs were tested as potential cancer nanotherapeutics on colorectal carcinoma cells (HCT-116) and cervical cancer cells (HeLa) using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. In addition, the non-cancer embryonic kidney cells HEK-293 were taken as a control in the study. The cell viability assay demonstrated a significant reduction in cancer cell population post 48 h treatments of AuNPs, and Au/CNTs. The average cell viabilities of AuNPs, Au/CNTs, and CNTs for HCT-116 cells were 50.62%, 65.88%, 93.55%, and for HeLa cells, the cell viabilities were 50.88%, 66.51%, 91.73%. The cell viabilities for HEK-293 were 50.44%, 65.80%, 93.20%. Both AuNPs and Au/CNTs showed higher cell toxicity and cell death compared with CNT nanomaterials. The treatment of AuNPs and Au/CNTs showed strong inhibitory action on HCT-116 and HeLa cells. However, the treatment of CNTs did not significantly decrease HCT-116 and HeLa cells, and there was only a minor decrease. The treatment of AuNPs, and Au/CNTs, on normal HEK-293 cells also showed a significant decrease in cell viability, but the treatment of CNTs did not produce a significant decrease in the HEK-293 cells. This study shows that a simplified synthesis technique like laser synthesis for the preparation of high-purity nanomaterials has good efficacy for possible future cancer therapy with minimal toxicity.

Antimicrobial Nanomaterials: A Review

Microbial colonization on various surfaces is a serious problem. Biofilms from these microbes pose serious health and economic threats. In addition, the recent global pandemic has also attracted great interest in the latest techniques and technology for antimicrobial surface coatings. Incorporating antimicrobial nanocompounds into materials to prevent microbial adhesion or kill microorganisms has become an increasingly challenging strategy. Recently, many studies have been conducted on the preparation of nanomaterials with antimicrobial properties against diseases caused by pathogens. Despite tremendous efforts to produce antibacterial materials, there is little systematic research on antimicrobial coatings. In this article, we set out to provide a comprehensive overview of nanomaterials-based antimicrobial coatings that can be used to stop the spread of contamination to surfaces. Typically, surfaces can be simple deposits of nanomaterials, embedded nanomaterials, as well as nanotubes, nanowires, nanocolumns, nanofibers, nanoneedles, and bio-inspired structures.

Sonication-assisted liquid phase exfoliation of two-dimensional CrTe3 under inert conditions

Liquid phase exfoliation (LPE) has been used for the successful fabrication of nanosheets from a large number of van der Waals materials. While this allows to study fundamental changes of material properties’ associated with reduced dimensions, it also changes the chemistry of many materials due to a significant increase of the effective surface area, often accompanied with enhanced reactivity and accelerated oxidation. To prevent material decomposition, LPE and processing in inert atmosphere have been developed, which enables the preparation of pristine nanomaterials, and to systematically study compositional changes over time for different storage conditions. Here, we demonstrate the inert exfoliation of the oxidation-sensitive van der Waals crystal, CrTe3. The pristine nanomaterial was purified and size-selected by centrifugation, nanosheet dimensions in the fractions quantified by atomic force microscopy and studied by Raman, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX) and photo spectroscopic measurements. We find a dependence of the relative intensities of the CrTe3 Raman modes on the propagation direction of the incident light, which prevents a correlation of the Raman spectral profile to the nanosheet dimensions. XPS and EDX reveal that the contribution of surface oxides to the spectra is reduced after exfoliation compared to the bulk material. Further, the decomposition mechanism of the nanosheets was studied by time-dependent extinction measurements after water titration experiments to initially dry solvents, which suggest that water plays a significant role in the material decomposition.

Synthesis of WO3 nanopowder using a green surfactant for efficient gas sensing applications

WO3 has attracted great attention for chemical gas sensing applications. However, the synthesis of WO3 is mainly performed by using hazardous organic solvents and corrosive acidic solutions, which can result in environmental and health issues. The development of safe synthesis procedures using green compounds and solvents is in great demand to overcome the aforementioned drawbacks. Therefore, the effect of different eco-friendly chemical compounds on the growth of WO3 materials has yet to be thoroughly studied. Meanwhile, the fabrication of material at the nanoscale with specific crystalline properties may improve its sensitivity to the target gas. In this work, we report an efficient method for the synthesis of WO3 nanopowder by using water and a green surfactant such as vitamin C. The growth mechanism of the structure is analyzed considering the nature of solutions and surfactants. The studies indicate that the surfactant has a crucial effect on the formation of nanoparticles. Furthermore, the experimental findings show that the fabricated monoclinic WO3 material is highly sensitive and selective to low concentrations of acetone. Moreover, the structure exhibits quite stable functionalities at different levels of environmental humidity. Hence, this work may have a considerable impact on the existing techniques for the preparation of WO3 nanomaterials providing new insights into their green synthesis procedures. In addition, it can significantly affect the development of high-performance gas sensors and other catalytic devices based on WO3 nanostructures.

A new high efficiency catalyst of Co–Ni/CeO2 for hydrogen production by ammonia oxidative decomposition at low temperature

Hydrogen production through ammonia decomposition at high temperatures is a promising approach, but lacks a simple and cost-effective process for efficient and rapid initiation of ammonia decomposition without external energy. To address this, the preparation of nanomaterials is crucial to achieve excellent ammonia oxidative decomposition performance. In this study, CeO2 with an ordered mesoporous structure was synthesized and supported with Co and Ni bimetals using a co-deposition method. Through various experimental characterization methods (XRD, BET, TEM, H2-TPR and XPS), a structure-activity relationship was established and a catalytic reaction mechanism was proposed. The catalyst with the best activity performance was found to be 5 wt % Co-5wt % Ni/CeO2 (CNC-55). With an NH3/O2 ratio of 4:1, the reaction temperature increased rapidly from 130 °C to 570 °C, the NH3 and O2 conversion rate can reach 95% and 100% respectively, and the H2 production rate can reaches 62%. The catalyst also exhibited good stability and reusability. Notably, the process only required ammonia and oxygen at low temperatures to produce hydrogen, nitrogen and water vapor, without the need for external energy or additional procedures.

Constructing atomically dispersed Snδ+ sites in porous carbon nanosheets to boost lithium-/sodium-storage capability

Nanoscale carbon-supported single atomic metal active centers (Mδ+) have recently caught much attention as a high-efficient catalyst in energy-conversion/-storage fields. Further works extended to employ these materials as the lithium-/sodium-storage anode. Inspired by the progresses, porous carbon nanosheets with abundant Snδ+ sites (Sn-PCNS) are prepared by easy-controllable template-directed method and post carbonization process in this work. Here, atomically dispersed Snδ+ is stabilized mainly by O/N moieties in carbon framework, which can enhance the electron transfer and Li+-/Na+-diffusion kinetics, thus benefiting the Li+-/Na+-storage capabilities. As a result, the Sn-PCNS electrode can deliver a high lithium-storage capacity of 428 mA h g−1 at 10 A g−1 and show a long-term cycling performance for sodium storage at high rate (∼ 120 mA h g−1 at 5 A g−1 after 1000 cycles). This work not only provides a strategy for the preparation of new sheet-like carbon-based nanomaterials, but also offer an opportunity to promote the application of carbon-supported single atomic metal active centers in energy conversion and storage.

Preparation and regulation of perovskite hydroxide nanomaterials

Preparation and regulation of perovskite hydroxide nanomaterials

Preparation and usage of nanomaterials in biomedicine.

Nanotechnology is one of the most promising and decisive technologies in the world. Nanomaterials, as the primary research aspect of nanotechnology, are quitedifferent from macroscopic materials because of their unique optical, electrical, magnetic, thermal properties, and more robust mechanical properties, which makethem play an essential role in the field of materials science, biomedical field, aerospace field, and environmental energy. Different preparation methods for nanomaterialshave various physical and chemical properties and are widely used in different areas. In this review, we focused on the preparation methods, including chemical, physical, and biological methods due to the properties of nanomaterials. We mainly clarified the characteristics, advantages, and disadvantages of different preparation methods. Then, we focused on the applications of nanomaterials in biomedicine, including biological detection, tumor diagnosis, and disease treatment, which provide a development trend and promising prospects for nanomaterials.

Recent Progress of Amorphous Nanomaterials.

Amorphous materials are metastable solids with only short-range order at the atomic scale, which results from local intermolecular chemical bonding. The lack of long-range order typical of crystals endows amorphous nanomaterials with unconventional and intriguing structural features, such as isotropic atomic environments, abundant surface dangling bonds, highly unsaturated coordination, etc. Because of these features and the ensuing modulation in electronic properties, amorphous nanomaterials display potential for practical applications in different areas. Motivated by these elements, here we provide an overview of the unique structural features, the general synthetic methods, and the potential for applications covered by contemporary research in amorphous nanomaterials. Furthermore, we discussed the possible theoretical mechanism for amorphous nanomaterials, examining how the unique structural properties and electronic configurations contribute to their exceptional performance. In particular, the structural benefits of amorphous nanomaterials as well as their enhanced electrocatalytic, optical, and mechanical properties, thereby clarifying the structure-function relationships, are highlighted. Finally, a perspective on the preparation and utilization of amorphous nanomaterials to establish mature systems with a superior hierarchy for various applications is introduced, and an outlook for future challenges and opportunities at the frontiers of this rapidly advancing field is proposed.

Nanomaterials Derived from a Template Method for Supercapacitor Applications

AbstractAs one of the effective methods for the preparation of nanomaterials, the main advantage of template synthesis method is that the chemical reactions occurring in the liquid phase or the gas phase are carried out within the scope of effective control. Compared with other ordinary methods, nanomaterials prepared by template method deliver various morphology and structure, which could deliver excellent electrochemical performance. In this review, template method has been divided into soft template and hard template, which the former is flexibility and ease of customization and the latter is accuracy and uniformity. But, the soft template lack precision and consistency, while hard template limits creativity and adaptability. In addition, the progress and prospect of template method have been provided.

Structure control and growth mechanism of beaded SiC nanowires with microwave absorption properties

Large-scale SiC nanowires (SiCnws) were successfully synthesized on graphite substrates by a catalyst-free carbon thermal reduction process using low-cost silicone oil, silica powder, and activated carbon. The control of different nanowire structures was achieved by parameter regulation. An in-depth discussion of their growth mechanisms is provided. Beaded SiCnws consisting of amorphous SiO2 beads and SiC strings were synthesized at 1400 °C. The formation of beads is mainly due to the supersaturation of SiO vapor, which leads to the reaction of excess SiO to form SiO2 at the defects of the SiCnws. The dielectric parameters of beaded SiCnws were analyzed, and it was found that the beaded SiCnws have a maximum effective absorption width of 1.84 GHz and a maximum reflection loss of −16.03 dB. The exploration of the growth mechanism of beaded SiCnws in this study provides a useful reference for the preparation of one-dimensional nanomaterials.