Solid-phase catalytic reactions of tritium with carbohydrates: 4. Mechanism of isomerization of <Emphasis Type="Italic">D</Emphasis>-glucose in the course of solid-phase catalytic hydrogenation with tritium

The influence exerted on solid-phase catalytic hydrogenation (SCH) of D-glucose with tritium by the temperature varied in the range 90–140°C, platinum group catalysts, solid phase composition, reaction time, and surface area of the support was examined. Fructose and mannose were identified in the reaction products along with labeled glucose. The mechanism of the isomerization of glucose into fructose and mannose in the solid phase under the action of hydrogen spillover was suggested. The glucose isomerization occurs by a complex mechanism analogous to acid-catalyzed keto-enol tautomerization of epimeric sugars in solution, and the active species in SCH of D-glucose with tritium is spillover hydrogen in the form of proton.     

Engineering Biomimetic Nanofiber Microspheres with Tailored Size,Predesigned Structure,and Desired Composition via Gas Bubble–Mediated Coaxial Electrospray

Minimally invasive therapies avoiding surgical complexities evoke great interest in developing injectable biomedical devices. Herein, a versatile approach is reported for engineering injectable and biomimetic nanofiber microspheres (NMs) with tunable sizes, predesigned structures, and desired compositions via gas bubble–mediated coaxial electrospraying. The sizes and structures of NMs are controlled by adjusting processing parameters including air flow rate, applied voltage, distance, and spinneret configuration in the coaxial setup. Importantly, unlike the self‐assembly method, this technique can be used to fabricate NMs from any material feasible for electrospinning or other nanofiber fabrication techniques. To demonstrate the versatility, open porous NMs are successfully fabricated that consist of various short nanofibers made of poly(ε‐caprolactone), poly(lactic‐co‐glycolic acid), gelatin, methacrylated gelatin, bioglass, and magneto‐responsive polymer composites. Open porous NMs support human neural progenitor cell growth in 3D with a larger number and more neurites than nonporous NMs. Additionally, highly open porous NMs show faster cell infiltration and host tissue integration than nonporous NMs after subcutaneous injection to rats. Such a novel class of NMs holds great potential for many biomedical applications such as tissue filling, cell and drug delivery, and minimally invasive tissue regeneration.     

Pathways of nanotoxicity: Modes of detection,impact, and challenges

Nanotoxicology has become the subject of intense research for more than two decades. Thousands of articles have been published but the space in understanding the nanotoxicity mechanism and the assessment is still unclear. Recent researches clearly show potential benefits of nanomaterials (NMs) in diagnostics and treatment, targeted drug delivery, and tissue engineering owing to their excellent physicochemical properties. However, these NMs display hazardous health effect then to the greater part of the materials because of small size, large surface area-to-volume ratio, quantum size effects, and environmental factors. Nowadays, a large number of NMs are used in industrial products including several medical applications, consumer, and healthcare products. However, they came into the environment without any safety test. The measurement of toxicity level has become important because of increasing toxic effects on living organisms. New realistic mechanism-based strategies are still needed to determine the toxic effects of NMs. For the assessment of NMs toxicity, reliable and standardized procedures are necessary. This review article provides systematic studies on toxicity of NMs involving manufacturing, environmental factors, eco-toxic and genotoxic effects, some parameters which have been ignored of NMs versus their biological counterparts, cell heterogeneity, and their current challenges and future perspectives.     

Advanced Nanotechnology Leading the Way to Multimodal Imaging‐Guided Precision Surgical Therapy

Surgical resection is the primary and most effective treatment for most patients with solid tumors. However, patients suffer from postoperative recurrence and metastasis. In the past years, emerging nanotechnology has led the way to minimally invasive, precision and intelligent oncological surgery after the rapid development of minimally invasive surgical technology. Advanced nanotechnology in the construction of nanomaterials (NMs) for precision imaging‐guided surgery (IGS) as well as surgery‐assisted synergistic therapy is summarized, thereby unlocking the advantages of nanotechnology in multimodal IGS‐assisted precision synergistic cancer therapy. First, mechanisms and principles of NMs to surgical targets are briefly introduced. Multimodal imaging based on molecular imaging technologies provides a practical method to achieve intraoperative visualization with high resolution and deep tissue penetration. Moreover, multifunctional NMs synergize surgery with adjuvant therapy (e.g., chemotherapy, immunotherapy, phototherapy) to eliminate residual lesions. Finally, key issues in the development of ideal theranostic NMs associated with surgical applications and challenges of clinical transformation are discussed to push forward further development of NMs for multimodal IGS‐assisted precision synergistic cancer therapy.     

Microfluidic Generation of Nanomaterials for Biomedical Applications

As nanomaterials (NMs) possess attractive physicochemical properties that are strongly related to their specific sizes and morphologies, they are becoming one of the most desirable components in the fields of drug delivery, biosensing, bioimaging, and tissue engineering. By choosing an appropriate methodology that allows for accurate control over the reaction conditions, not only can NMs with high quality and rapid production rate be generated, but also designing composite and efficient products for therapy and diagnosis in nanomedicine can be realized. Recent evidence implies that microfluidic technology offers a promising platform for the synthesis of NMs by easy manipulation of fluids in microscale channels. In this Review, a comprehensive set of developments in the field of microfluidics for generating two main classes of NMs, including nanoparticles and nanofibers, and their various potentials in biomedical applications are summarized. Furthermore, the major challenges in this area and opinions on its future developments are proposed.     

Nanomaterials and the environment: a review for the biennium 2008-2010

Applications of nanotechnology are touching almost every aspect of modern life. The increased use of engineered nanomaterials (ENMs) in consumer products, chemical and medical equipment, information technology, and energy, among others, has increased the number of publications (informative and scientific) on ENMs. By the 1950s, very few papers were committed to nanomaterials (NMs), but in 2009, more than 80,000 journal articles included the concept nanotechnology. The objective of this review is to compile and analyze publications on NMs in the biennium 2008-2010. This review includes the most recent publications in risk assessment/toxicity, characterization and stability, toxicity, fate and transport of NMs in terrestrial ecosystems, and new ENMs. Carbon nanotubes, metallic, metal oxides and hydroxides nanoparticles, quantum dots, and polystyrene NPs are included.     

Optical and electrochemical properties of multilayer polyelectrolyte thin films incorporating spherical, gold colloid nanomaterials

Polyelectrolyte multilayer (PEM) films incorporating various types of spherical, gold nanomaterials (NMs) were investigated to assess the existence of electrochemical and/or optical signal enhancement effects directly attributable to embedded NMs and the relationship of these effects to film structure and composition. Specifically, electrostatically assembled films of cationic poly-l-lysine (PLL) and anionic poly(4-styrene sulfonate) (PSS) incorporating one of four types of spherical, gold colloid NMs were constructed on 3-(aminopropyl)trimethoxysilane (3-APTMS)-modified glass substrates for optical studies or 11-mercaptoundecanoic (MUA)-modified gold electrodes for electrochemical studies. The NMs inserted into the PEM films include citrate-stabilized gold nanoparticles, thioctic acid-stabilized gold nanoparticles (TAS-NPs), MUA-modified monolayer protected gold clusters, and hollow gold nanoshells (Au-NSs). Optical sensitivity of the NM-embedded films, in terms of absorbance, surface plasmon band shifts, and the dependence of these optical responses on film thickness, varied depending on the type of NM within the film (e.g., TAS-NPs versus Au-NSs) but exhibited no corresponding electrochemical effects in the diffusional voltammetry of a ferricyanide redox probe. While not correlated to optical responses, the increased Faradaic current achieved during voltammetry at NM-embedded PEM films suggested that electrochemical effects of NMs were less dependent on the type of NMs and were, instead, more related to their location within the film and the electrostatic interactions built into the interfacial chemistry of the films. These results should prove useful for developing strategies constructing thin films with NMs that are specifically designed for optical or electrochemical sensing, taking full advantage of the signal enhancements provided by individual types of NMs.     

Nanomaterial Transformations in the Environment: Effects of Changing Exposure Forms on Bioaccumulation and Toxicity

In the environment, nanomaterials (NMs) are subject to chemical transformations, such as redox reactions, dissolution, coating degradation, and organic matter, protein, and macromolecule binding, and physical transformations including homo or heteroagglomeration. The combination of these reactions can result in NMs with differing characteristics progressing through a functional fate pathway that leads to the formation of transformed NM functional fate groups with shared properties. To establish the nature of such effects of transformation on NMs, four main types of studies are conducted: 1) chemical aging for transformation of pristine NMs; 2) manipulation of test media to change NM surface properties; 3) aging of pristine NMs water, sediment, or soil; 4) NM aging in waste streams and natural environments. From these studies a paradigm of aging effects on NM uptake and toxicity can be developed. Transformation, especially speciation changes, largely results in reduced potency. Further reactions at the surface resulting in processes, such as ecocorona formation and heteroagglomeration may additionally reduce NM potency. When NMs of differing potency transform and enter environments, common transformation reaction occurring in receiving system may act to reduce the variation in hazard between different initial NMs leading to similar actual hazard under realistic exposure conditions.     

Metal oxide nanomaterials in seawater: linking physicochemical characteristics with biological response in sea urchin development

The fate and behavior of nanomaterials (NMs) in environmental media has important consequences for toxicity. The majority of aquatic research to date has focused on NM behavior in freshwater systems. However, pH and salinity differences of seawater affect dissolution and aggregation of NMs. In this study, physical characteristics of metal oxide NMs in seawater were linked with their toxicity to developing sea urchins. The metal oxide NMs TiO₂ and CeO₂ up to 10 mg/L were not toxic to the embryos of the white sea urchin (Lytechinus pictus). In contrast, ZnO NM was highly toxic to these embryos (EC₅₀ = 99.5 μg/L). The toxicity of ZnO NM was not significantly different from bulk ZnO or soluble Zn²⁺ (from ZnSO₄·7H₂O), suggesting that the toxicity of ZnO NM can be attributed to soluble Zn²⁺. Furthermore, solubility data indicate that at the concentrations used in our sea urchin embryo experiments, ZnO NM was rapidly and completely solubilized in seawater. The present study also demonstrated that Fe-doped NMs were less soluble in seawater compared to pure ZnO NMs, but there was no concomitant reduction in toxicity.     

Nano or Not Nano? A Structured Approach for Identifying Nanomaterials According to the European Commission’s Definition

Identifying nanomaterials (NMs) according to European Union legislation is challenging, as there is an enormous variety of materials, with different physico‐chemical properties. The NanoDefiner Framework and its Decision Support Flow Scheme (DSFS) allow choosing the optimal method to measure the particle size distribution by matching the material properties and the performance of the particular measurement techniques. The DSFS leads to a reliable and economic decision whether a material is an NM or not based on scientific criteria and respecting regulatory requirements. The DSFS starts beyond regulatory requirements by identifying non‐NMs by a proxy approach based on their volume‐specific surface area. In a second step, it identifies NMs. The DSFS is tested on real‐world materials and is implemented in an e‐tool. The DSFS is compared with a decision flowchart of the European Commission’s (EC) Joint Research Centre (JRC), which rigorously follows the explicit criteria of the EC NM definition with the focus on identifying NMs, and non‐NMs are identified by exclusion. The two approaches build on the same scientific basis and measurement methods, but start from opposite ends: the JRC Flowchart starts by identifying NMs, whereas the NanoDefiner Framework first identifies non‐NMs.     

Multiwalled carbon nanotube-poly(vinyl alcohol)-glucose oxidase nanobiocomposites for amperometric sensing

Novel nanobiocomposites multiwalled carbon nanotube-poly(vinyl alcohol)-glucose oxidase have been successfully prepared by a simple solution-evaporation method. The morphology and performance of the multiwalled carbon nanotube-poly(vinyl alcohol)-glucose oxidase film have been characterized by atomic force microscopy, cyclic voltammetry, and amperometry. The multiwalled carbon nanotube and glucose oxidase were observed to be homogeneously dispersed throughout the poly(vinyl alcohol) matrix. When compared with bare glassy carbon electrode, the sensitivity to hydrogen peroxide is greatly improved by about 115 times at multiwalled carbon nanotubepoly(vinyl alcohol) modified glassy carbon electrode. The glucose biosensor sensitivity was strongly influenced by the glucose oxidase concentration within the multiwalled carbon nanotube-poly(vinyl alcohol)-glucose oxidase composite.     

Air-Stable Radical Organic Cages as Cascade Nanozymes for Enhanced Catalysis

The pursuit of single-assembled molecular cage reactors for complex tandem reactions is a long-standing target in biomimetic catalysis but still a grand challenge. Herein, nanozyme-like organic cages are reported by engineering air-stable radicals into the skeleton upon photoinduced electron transfer. The generation of radicals is accompanied by single-crystal structural transformation and exhibits superior stability over six months in air. Impressively, the radicals throughout the cage skeleton can mimic the peroxidase of natural enzymes to decompose H₂O₂ into OH · and facilitate oxidation reactions. Furthermore, an integrated catalyst by encapsulating Au clusters (glucose oxidase mimics) into the cage has been developed, in which the dual active sites (Au cluster and radical) are spatially isolated and can work as cascade nanozymes to prominently promote the enzyme-like tandem reaction via a substrate channeling effect.     

Nano–bio surface interactions,cellular internalisation in cancer cells and e‐data portals of nanomaterials: A review

Nanomaterials (NMs) have abundant applications in areas such as electronics, energy, environment industries, biosensors, nano devices, theranostic platforms, etc. Nanoparticles can increase the solubility and stability of drug‐loaded materials, enhance their internalisation, protect them from initial destruction in the biological system, and lengthen their circulation time. The biological interaction of proteins present in the body fluid with NMs can change the activity and natural surface properties of NMs. The size and charge of NMs, properties of the coated and uncoated NMs, nature of proteins, cellular interactions direct their internalisation pathway in the cellular system. Thus, the present review emphasises the impact of coated, uncoated NMs, size and charge, nature of proteins on nano–bio surface interactions and on internalisation with specific focus on cancer cells. The increased activity of NPs may also result in toxicity on health and environment, thus emphasis should be given to assess the toxicity of NMs in the medical field. The e‐data sharing portals of NMs have also been discussed in this review that will be helpful in providing the information about the chemical, physical, biological properties and toxicity of NMs.     

Metal-Based Nanozymes with Multienzyme-Like Activities as Therapeutic Candidates: Applications,Mechanisms, and Optimization Strategy

Most nanozymes in development for medical applications only exhibit single-enzyme-like activity, and are thus limited by insufficient catalytic activity and dysfunctionality in complex pathological microenvironments. To overcome the impediments of limited substrate availabilities and concentrations, some metal-based nanozymes may mimic two or more activities of natural enzymes to catalyze cascade reactions or to catalyze multiple substrates simultaneously, thereby amplifying catalysis. Metal-based nanozymes with multienzyme-like activities (MNMs) may adapt to dissimilar catalytic conditions to exert different enzyme-like effects. These multienzyme-like activities can synergize to realize “self-provision of the substrate,” in which upstream catalysts produce substrates for downstream catalytic reactions to overcome the limitation of insufficient substrates in the microenvironment. Consequently, MNMs exert more potent antitumor, antibacterial, and anti-inflammatory effects in preclinical models. This review summarizes the cellular effects and underlying mechanisms of MNMs. Their potential medical utility and optimization strategy from the perspective of clinical requirements are also discussed, with the aim to provide a theoretical reference for the design, development, and therapeutic application of their catalytic effects.     

原位相转化反应制备的金属/金属氧化物用于析氧反应

金属/金属氧化物复合材料凭借其独特的界面和电子结构已被广泛设计合成,并应用于碱性溶液中电催化析氧反应的电催化剂.然而,如何设计并获得丰富的金属/金属氧化物界面和均匀分散的金属相仍是一个挑战.此外,金属和金属氧化物在增强电催化活性方面的协同机理依然不清晰.本文以金属氧化物为基体,通过锂诱导的转化反应,制备了具有丰富界面和...     

Modulating the growth of cysteine-capped cadmium sulfide quantum dots with enzymatically produced hydrogen peroxide

Cysteine (CSH) readily stabilizes cadmium sulfide quantum dots (CdS QDs) that grow in aqueous buffered solutions.The oxidation of CSH by hydrogen peroxide (H2O2) at room temperature yields cystine (CSSC),which is less efficient in stabilizing CdS QDs compared to CSH.Herein,we demonstrate that such oxidation causes a decrease in the formation rate of CSH-capped CdS QDs from Cd2+ and S2-ions.For the first time,we combined the oxidation of CSH with the glucose oxidase (GOx)-assisted biocatalytic oxidation of D-glucose,which leads to a buildup of H2O2 in the reaction mixture.The enzymatically modulated in situ growth of CdS QDs was monitored using two techniques:fluorescence spectroscopy and photoelectrochemical (PEC) analysis.This system enables quantification of GOx and glucose in human serum.     

RhRu Alloy-Anchored MXene Nanozyme for Synergistic Osteosarcoma Therapy

Noble metal nanozymes hold promise in cancer therapy due to adjustable enzyme-like activities, unique physicochemical properties, etc. But catalytic activities of monometallic nanozyme are confined. In this study, 2D titanium carbide (Ti₃C₂T_x)-supported RhRu alloy nanoclusters (RhRu/Ti₃C₂T_x) are prepared by a hydrothermal method and utilized for synergistic therapy of chemodynamic therapy (CDT), photodynamic therapy (PDT), and photothermal therapy (PTT) on osteosarcoma. The nanoclusters are small in size (3.6 nm), uniform in distribution, and have excellent catalase (CAT) and peroxidase (POD)-like activities. Density functional theory calculations show that there is a significant electron transfer interaction between RhRu and Ti₃C₂T_x, which has strong adsorption to H₂O₂ and is beneficial to enhance the enzyme-like activity. Furthermore, RhRu/Ti₃C₂T_x nanozyme acts as both PTT agent for converting light into heat, and photosensitizer for catalyzing O₂ to ¹O₂. With the NIR-reinforced POD- and CAT-like activity, excellent photothermal and photodynamic performance, the synergistic CDT/PDT/PTT effect of RhRu/Ti₃C₂T_x on osteosarcoma is verified by in vitro and in vivo experiments. This study is expected to provide a new research direction for the treatment of osteosarcoma and other tumors.     

Review: nanoparticles and nanostructured materials in papermaking

The introduction of nanoparticles (NPs) and nanostructured materials (NSMs) in papermaking originally emerged from the perspective of improving processing operations and reducing material consumption. However, a very broad range of nanomaterials (NMs) can be incorporated into the paper structure and allows creating paper products with novel properties. This review is of interdisciplinary nature, addressing the emerging area of nanotechnology in papermaking focusing on resources, chemical synthesis and processing, colloidal properties, and deposition methods. An overview of different NMs used in papermaking together with their intrinsic properties and a link to possible applications is presented from a chemical point of view. After a brief introduction on NMs classification and papermaking, their role as additives or pigments in the paper structure is described. The different compositions and morphologies of NMs and NSMs are included, based on wood components, inorganic, organic, carbon-based, and composite NPs. In a first approach, nanopaper substrates are made from fibrillary NPs, including cellulose-based or carbon-based NMs. In a second approach, the NPs can be added to a regular wood pulp as nanofillers or used in coating compositions as nanopigments. The most important processing steps for NMs in papermaking are illustrated including the internal filling of fiber lumen, LbL deposition or fiber wall modification, with important advances in the field on the in situ deposition of NPs on the paper fibers. Usually, the manufacture of products with advanced functionality is associated with complex processes and hazardous materials. A key to success is in understanding how the NMs, cellulose matrix, functional additives, and processes all interact to provide the intended paper functionality while reducing materials waste and keeping the processes simple and energy efficient.     

Defect-Rich Adhesive Molybdenum Disulfide/rGO Vertical Heterostructures with Enhanced Nanozyme Activity for Smart Bacterial Killing Application

Nanomaterials with intrinsic enzyme-like activities, namely “nanozymes,” are showing increasing potential as a new type of broad-spectrum antibiotics. However, their feasibility is still far from satisfactory, due to their low catalytic activity, poor bacterial capturing capacity, and complicated material design. Herein, a facile synthesis of a defect-rich adhesive molybdenum disulfide (MoS₂)/rGO vertical heterostructure (VHS) through a one-step microwave-assisted hydrothermal method is reported. This simple, convenient but effective method for rapid material synthesis enables extremely uniform and well-dispersed MoS₂/rGO VHS with abundant S and Mo vacancies and rough surface, for a performance approaching the requirements of practical application. It is demonstrated experimentally and theoretically that the as-prepared MoS₂/rGO VHS possesses defect and irradiation dual-enhanced triple enzyme-like activities (oxidase, peroxidase, and catalase) for promoting free-radical generation, owing to much more active edge sites exposure. Meanwhile, the VHS-achieved rough surface exhibits excellent capacity for bacterial capture, with elevated reactive oxygen species (ROS) destruction through local topological interactions. As a result, optimized efficacy against drug-resistant Gram-negative and Gram-positive bacteria can be explored by such defect-rich adhesive nanozymes, demonstrating a simple but powerful way to engineered nanozymes for alternative antibiotics.     

Photothermal-Switched Single-Atom Nanozyme Specificity for Pretreatment and Sensing

Various applications lead to the requirement of nanozymes with either specific activity or multiple enzyme-like activities. To this end, intelligent nanozymes with freely switching specificity abilities hold great promise to adapt to complicated and changeable practical conditions. Herein, a nitrogen-doped carbon-supported copper single-atom nanozyme (named Cu SA/NC) with switchable specificity is reported. Atomically dispersed active sites endow Cu SA/NC with specific peroxidase-like activity at room temperature. Furthermore, the intrinsic photothermal conversion ability of Cu SA/NC enables the specificity switch by additional laser irradiation, where photothermal-induced temperature elevation triggers the expression of oxidase-like and catalase-like activity of Cu SA/NC. For further applications in practice, a pretreatment-and-sensing integration kit (PSIK) is constructed, where Cu SA/NC can successively achieve sample pretreatment and sensitive detection by switching from multi-activity mode to specific-activity mode. This study sets the foundation for nanozymes with switchable specificity and broadens the application scope in point-of-care testing.