Quantum dots‐based chemiluminescence probes: an overview

This mini‐review describes the recent developments in quantum dots‐based nanoprobes in liquid‐phase chemiluminescence (CL) analysis. In the referenced reports, multiple quantum dots (QDs) were adopted as final emission species either after direct oxidation reactions (direct CL) or after chemiluminescence resonance energy transfer (indirect CL). This review does not include papers in which QDs have been used as enhancers, catalysts, carriers or quenchers in chemiluminescence systems. A brief overview on the CL mechanisms of various QDs‐based nanoprobes and their analytical applications over the last decade is given, followed by comments on the future challenges and prospects in this field.     

High‐Temperature Shock Enabled Nanomanufacturing for Energy‐Related Applications

Functional nanomaterials are playing a crucial role in the emerging field of energy‐related devices. Recently, as a novel synthesis method, high‐temperature shock (HTS), which is rapid, low cost, eco‐friendly, universal, scalable, and controllable, has provided a promising option for the rational design and synthesis of various high‐quality nanomaterials. In this report, the HTS technique, including the equipment setup and operating principle, is systematically introduced, and recent progress in the synthesis of nanomaterials for energy storage and conversion applications using this HTS method is summarized. The growth mechanisms of nanoparticles and carbonaceous nanomaterials are thoroughly discussed, followed by the summary of the characteristic advantages of the HTS strategy. A series of nanomaterials prepared by the HTS method, including carbon‐based films, metal nanoparticles and compound nanoparticles, show high performance in the diverse applications of storage energy batteries, highly active catalysts, and smart energy devices. Finally, the future perspectives and directions of HTS in nanomanufacturing for broader applications are presented.     

Structure Design and Composition Engineering of Carbon‐Based Nanomaterials for Lithium Energy Storage

Carbon‐based nanomaterials have significantly pushed the boundary of electrochemical performance of lithium‐based batteries (LBs) thanks to their excellent conductivity, high specific surface area, controllable morphology, and intrinsic stability. Complementary to these inherent properties, various synthetic techniques have been adopted to prepare carbon‐based nanomaterials with diverse structures and different dimensionalities including 1D nanotubes and nanorods, 2D nanosheets and films, and 3D hierarchical architectures, which have been extensively applied as high‐performance electrode materials for energy storage and conversion. The present review aims to outline the structural design and composition engineering of carbon‐based nanomaterials as high‐performance electrodes of LBs including lithium‐ion batteries, lithium–sulfur batteries, and lithium–oxygen batteries. This review mainly focuses on the boosting of electrochemical performance of LBs by rational dimensional design and porous tailoring of advanced carbon‐based nanomaterials. Particular attention is also paid to integrating active materials into the carbon‐based nanomaterials, and the structure–performance relationship is also systematically discussed. The developmental trends and critical challenges in related fields are summarized, which may inspire more ideas for the design of advanced carbon‐based nanostructures with superior properties.     

Graphene Quantum Dots‐Based Advanced Electrode Materials: Design,Synthesis and Their Applications in Electrochemical Energy Storage and Electrocatalysis

Graphene quantum dots (GQDs) have aroused great interest in the scientific community in recent years due to their unique physicochemical properties and potential applications in different fields. To date, much research has been conducted on the ingenious design and rational construction of GQDs‐based nanomaterials used as electrode materials and/or electrocatalysts. Despite these efforts, research on the efficient synthesis and application of GQDs‐based nanomaterials is still in the early stages of development and timely updates of recent research progress on new design concepts, synthetic strategies, and significant breakthroughs in GQDs‐based nanomaterials are highly desired. In light of the above, the effect of synthetic methods on the final product of the GQDs, the GQDs synthesis mechanism, and specific perspectives regarding the effect of the unique surface and structural properties of GQDs (e.g., defects, heteroatom doping, surface/edge state, size, conductivity) on the electrochemical energy‐related systems are discussed in‐depth in this review. Additionally, this review also focuses on the design of GQDs‐based composites and their applications in the fields of electrochemical energy storage (e.g., supercapacitors and batteries) and electrocatalysis (e.g., fuel cell, water splitting, CO₂ reduction), along with constructive suggestions for addressing the remaining challenges in the field.     

One‐pot synthesis of fluorescent nitrogen‐doped carbon dots with good biocompatibility for cell labeling

Here we report an easy and economical hydrothermal carbonization approach to synthesize the fluorescent nitrogen‐doped carbon dots (N‐CDs) that was developed using citric acid and triethanolamine as the precursors. The synthesis conditions were optimized to obtain the N‐CDs with superior fluorescence performances. The as‐prepared N‐CDs are monodispersed sphere nanoparticles with good water solubility, and exhibited strong fluorescence, favourable photostability and excitation wavelength‐dependent behavior. Furthermore, the in vitro cytotoxicity and cellular labeling of N‐CDs were investigated using the rat glomerular mesangial cells. The results showed the N‐CDs have more inconspicuous cytotoxicity and better biosafety in comparison with ZnSe quantum dots, although both targeted the cells successfully. Considering their admirable photostability, low toxicity and good compatibility, the as‐obtained N‐CDs could have potential applications in biosensors, cellular imaging, and other fields.     

Life Cycle Energy and Climate Change Implications of Nanotechnologies

The potential environmental and health impacts of nanotechnologies triggered a recent surge of life cycle assessment (LCA) studies on nanotechnologies. Focusing on the energy use and greenhouse gas emissions impacts, we reviewed 22 LCA‐based studies on nanomaterials, coatings, photovoltaic devices, and fabrication technologies that were published until 2011. The reviewed LCA studies indicate that nanomaterials have higher cradle‐to‐gate energy demand per functional unit, and thus higher global warming impact, than their conventional counterparts. Depending on the synthesis method, carbon‐based nanoparticles (i.e., carbon nanofibers, carbon nanotubes, and fullerenes) require 1 to 900 gigajoules per kilogram (GJ/kg) of primary energy to produce, compared with ～200 megajoules per kilogram (MJ/kg) for aluminum. This is mainly attributed to the fact that nanomaterials involve an energy‐intensive synthesis process or an additional mechanical process to reduce particle size. Most reviewed studies ascertain, however, that the cradle‐to‐grave energy demand and global warming impact from nanotechnologies at a device level are lower than from conventional technologies because nanomaterials are typically used in a small amount to improve functionality and the upgraded functionality offers more energy‐efficient operation of the device. Because of the immature status of most nanotechnologies, the studies reviewed here often rely on inventory data estimated from literature values and parametric analyses based on laboratory or prototype production, warranting future analyses to confirm the current findings.     

Carbon Nanomaterials for Dye‐Sensitized Solar Cell Applications: A Bright Future

There is an urgent need for alternative energy resources due to the rapid rise in the price of fossil fuels and the great danger of the increasing greenhouse effect caused by carbon dioxide emission. Sunlight provides by far the largest of all carbon‐neutral energy sources. Therefore, the current solar‐ or photovoltaic‐cell‐based technologies, which can utilize solar energy, are of extreme importance. Dye‐sensitized solar cells (DSSCs) are of particular interest because they can offer a number of advantages when compared to existing photovoltaic technologies. In this review, recent advances in carbon‐related nanomaterials and their application as materials for DSSCs are discussed. Carbon nanomaterials such as carbon nanotubes and graphene display remarkable electrical, thermal, and mechanical properties that enable several exciting applications in DSSCs. The progress on the utilisation of carbon nanotubes, graphene, and their nanocomposites is reviewed as highly prospective materials to replace transparent conductive oxide (TCO) layers and counter electrodes in DSSCs. Moreover, carbon nanomaterials enable improvement of the performance of absorbing layers in working photoanodes by enhancing the light absorption and electron transport across the semiconducting nanostructured film. The application of carbon nanotubes, graphite particles, and graphene as additives towards the improved efficiency of the electrolyte in these solar cells is also discussed. Finally, a brief outlook is provided on the future development of carbon nanomaterial composites as prospective materials for DSSCs, particularly as components for printable solar cells, which are expected to play an important role in the future solar‐cell market.     

Tailored carbon nanotubes for tissue engineering applications

A decade of aggressive researches on carbon nanotubes (CNTs) has paved way for extending these unique nanomaterials into a wide range of applications. In the relatively new arena of nanobiotechnology, a vast majority of applications are based on CNTs, ranging from miniaturized biosensors to organ regeneration. Nevertheless, the complexity of biological systems poses a significant challenge in developing CNT‐based tissue engineering applications. This review focuses on the recent developments of CNT‐based tissue engineering, where the interaction between living cells/tissues and the nanotubes have been transformed into a variety of novel techniques. This integration has already resulted in a revaluation of tissue engineering and organ regeneration techniques. Some of the new treatments that were not possible previously become reachable now. Because of the advent of surface chemistry, the CNT's biocompatibility has been significantly improved, making it possible to serve as tissue scaffolding materials to enhance the organ regeneration. The superior mechanic strength and chemical inert also makes it ideal for blood compatible applications, especially for cardiopulmonary bypass surgery. The applications of CNTs in these cardiovascular surgeries led to a remarkable improvement in mechanical strength of implanted catheters and reduced thrombogenecity after surgery. Moreover, the functionalized CNTs have been extensively explored for in vivo targeted drug or gene delivery, which could potentially improve the efficiency of many cancer treatments. However, just like other nanomaterials, the cytotoxicity of CNTs has not been well established. Hence, more extensive cytotoxic studies are warranted while converting the hydrophobic CNTs into biocompatible nanomaterials. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

Graphene‐Based Nanocomposites for Energy Storage

Since the first report of using micromechanical cleavage method to produce graphene sheets in 2004, graphene/graphene‐based nanocomposites have attracted wide attention both for fundamental aspects as well as applications in advanced energy storage and conversion systems. In comparison to other materials, graphene‐based nanostructured materials have unique 2D structure, high electronic mobility, exceptional electronic and thermal conductivities, excellent optical transmittance, good mechanical strength, and ultrahigh surface area. Therefore, they are considered as attractive materials for hydrogen (H₂) storage and high‐performance electrochemical energy storage devices, such as supercapacitors, rechargeable lithium (Li)‐ion batteries, Li–sulfur batteries, Li–air batteries, sodium (Na)‐ion batteries, Na–air batteries, zinc (Zn)–air batteries, and vanadium redox flow batteries (VRFB), etc., as they can improve the efficiency, capacity, gravimetric energy/power densities, and cycle life of these energy storage devices. In this article, recent progress reported on the synthesis and fabrication of graphene nanocomposite materials for applications in these aforementioned various energy storage systems is reviewed. Importantly, the prospects and future challenges in both scalable manufacturing and more energy storage‐related applications are discussed.     

Emergent Pseudocapacitance of 2D Nanomaterials

Two dimensional (2D) nanomaterials are very attractive due to their unique structural and surface features for energy storage applications. Motivated by the recent pioneering works demonstrating “the emergent pseudocapacitance of 2D nanomaterials,” the energy storage and nanoscience communities could revisit bulk layered materials though state‐of‐the‐art nanotechnology such as nanostructuring, nanoarchitecturing, and compositional control. However, no review has focused on the fundamentals, recent progress, and outlook on this new mechanism of 2D nanomaterials yet. In this study, the key aspects of emergent pseudocapacitors based on 2D nanomaterials are comprehensively reviewed, which covers the history, classification, thermodynamic and kinetic aspects, electrochemical characteristics, and design guidelines of materials for extrinsically surface redox and intercalation pseudocapacitors. The structural and compositional controls of graphene and other carbon nanosheets, transition metal oxides and hydroxides, transition metal dichalcogenides, and metal carbide/nitride on both microscopic and macroscopic levels will be particularly addressed, emphasizing the important results published since 2010. Finally, perspectives on the current impediments and future directions of this field are offered. Unlimited combinations and modifications of 2D nanomaterials can provide a rational strategy to overcome intrinsic limitations of existing materials, offering a new‐generation energy storage materials toward a high and new position in the Ragone plot.     

Progress on carbon dots and hydroxyapatite based biocompatible luminescent nanomaterials for cancer theranostics

Despite the significant advancement in cancer diagnosis and therapy, a huge burden remains. Consequently, much research has been diverted on the development of multifunctional nanomaterials for improvement in conventional diagnosis and therapy. Luminescent nanomaterials offer a versatile platform for the development of such materials as their intrinsic photoluminescence (PL) property offers convergence of diagnosis as well as therapy at the same time. However, the clinical translation of nanomaterials faces various challenges, including biocompatibility and cost-effective scale up production. Thus, luminescent materials with facile synthesis approach along with intrinsic biocompatibility and anticancerous activity hold significant importance. As a result, carbon dots (CDs) and nanohydroxyapatite (nHA) have attracted much attention for the development of optical imaging probes. CDs are the newest members of the carbonaceous nanomaterials family that possess intrinsic luminescent and therapeutic properties, making them a promising candidate for cancer theranostic. Additionally, nHA is an excellent bioactive material due to its compositional similarity to the human bone matrix. The nHA crystal can efficiently host rare-earth elements to attain luminescent property, which can further be implemented for cancer theranostic applications. Herein, the development of CDs and nHA based nanomaterials as multifunctional agents for cancer has been briefly discussed. The emphasis has been given to different synthesis strategies leading to different morphologies and tunable PL spectra, followed by their diverse applications as biocompatible theranostic agents. Finally, the review has been summarized with the current challenges and future perspectives.     

Hollow Carbon Spheres and Their Hybrid Nanomaterials in Electrochemical Energy Storage

Electrochemical energy storage is of extraordinary importance for fulfilling the utilization of renewable and sustainable energy sources. There is an increasing demand for energy storage devices with high energy and power densities, prolonged stability, safety, and low cost. In the past decade, numerous research efforts have been devoted to achieving these requirements, especially in the design of advanced electrode materials. Hollow carbon spheres (HCS) derived nanomaterials combining the advantages of 3D HCS and porous structures have been considered as alternative electrode materials for advanced energy storage applications, due to their unique features such as high surface‐to‐volume ratios, encapsulation capability, together with outstanding chemical and thermal stability. In this review, the authors first present a comprehensive overview of the synthetic strategies of HCS, and elucidate the design and synthesis of HCS‐derived nanomaterials including various types of HCS and their nanohybrids. Additionally, their significant roles as electrode materials for supercapacitors, lithium‐ion or sodium‐ion batteries, and sulfur hosts for lithium sulfur batteries are highlighted. Finally, current challenges in the synthesis of HCS and future directions in HCS‐derived nanomaterials for energy storage applications are proposed.     

Liquid–Solid Interfacial Assemblies of Soft Materials for Functional Freestanding Layered Membrane–Based Devices toward Electrochemical Energy Systems

Freestanding layered membrane–based devices have broad applications in highly efficient energy‐storage/conversion systems. The liquid–solid interface is considered as a unique yet versatile interface for constructing such layered membrane–based devices. In this review, the authors outline recent developments in the fabrication of soft materials to functionalize layered devices from the aspect of liquid–solid interfacial assembly and engineering arts. Seven liquid–solid interfacial assembly strategies, including flow‐directed, superlattice, solvent‐casting, evaporation‐induced, dip‐coating, spinning, and electrospinning assemblies, are comprehensively highlighted with a focus on their synthetic pathways, formation mechanisms, and interface engineering strategies. Meanwhile, recent representative works on layered membrane–based devices for electrochemical energy applications are presented. Finally, challenges and opportunities of this research area are highlighted in order to stimulate future developments. This review not only offers comprehensive and practical approaches to assemble liquid–solid interfaces with soft materials for various important layered electrochemical energy devices but also sheds lights on fundamental insights by thoughtful discussions on performance enhancement mechanisms of these electrochemical energy systems.     

纳米水解酶的研究进展

水解酶由至少200种单独的蛋白质组成,可催化一系列独特化学键的水解.但是天然酶的固有缺点,如易变性、成本高、制备费力和回收困难,极大地限制了它们的实际应用.为了克服这些缺点,研究人员长期以来致力于探索人工水解酶模拟物.自从2007年发现Fe₃O₄纳米颗粒可以作为过氧化物酶模拟物,关于纳米酶的研究不断涌现.与天然酶相比,纳米酶具有制备简单、可大规模生产、环境耐受性强、制备及储存成本低廉、可重复使用等优势.纳米水解酶是指具有水解酶活性的纳米材料,金属有机框架材料、碳基纳米材料和金纳米粒子等的水解酶活性均已被报道.近年来,纳米水解酶研究领域进入蓬勃发展期,然而至今尚未见关于纳米水解酶的综述.本文首先根据水解底物的不同对纳米水解酶进行分类并分别讨论其催化机理,之后对影响纳米水解酶活性的因素及纳米水解酶的应用进行总结,最后概述和讨论纳米水解酶的当前挑战和未来前景.     

ZnO nanomaterials target mitochondrial apoptosis and mitochondrial autophagy pathways in cancer cells

In recent years, the application of engineering nanomaterials has significantly contributed to the development of various biomedical fields. Zinc oxide nanomaterials (ZnO NMts) have gained wide popularity due to their biocompatibility, unique physical and chemical properties, stability, and cost-effectiveness for large-scale production. They have emerged as potential materials for anticancer applications. This article provides a comprehensive review of the synthesis methods of ZnO NMts and highlights the advantages of combining ZnO NMts with anticancer drugs as a nano platform for cancer treatment. Additionally, the article briefly explains the mechanism of action of ZnO NMts in tumor cells, focusing on the mitochondrial pathways that target cell apoptosis and autophagy. It is observed that these pathways are primarily influenced by reactive oxygen species generated through oxidative stress. The article discusses the promising prospects of ZnO NMts combined with anticancer drugs in the field of cancer medicine and emphasizes the need for further in-depth research on the mitochondrial apoptosis and mitochondrial autophagy pathways.     

Nitrogen and sulfur co‐doped carbon nanodots toward bovine hemoglobin: A fluorescence quenching mechanism investigation

A deep understanding of the molecular interactions of carbon nanodots with biomacromolecules is essential for wider applications of carbon nanodots both in vitro and in vivo. Herein, nitrogen and sulfur co‐doped carbon dots (N,S‐CDs) with a quantum yield of 16% were synthesized by a 1‐step hydrothermal method. The N,S‐CDs exhibited a good dispersion, with a graphite‐like structure, along with the fluorescence lifetime of approximately 7.50 ns. Findings showed that the fluorescence of the N,S‐CDs was effectively quenched by bovine hemoglobin as a result of the static fluorescence quenching. The mentioned quenching mechanism was investigated by the Stern‐Volmer equation, temperature‐dependent quenching, and fluorescence lifetime measurements. The binding constants, number of binding sites, and the binding average distance between the energy donor N,S‐CDs and acceptor bovine hemoglobin were calculated as well. These findings will provide for valuable insights on the future bioapplications of N,S‐CDs.     

Recent Progress in Flexible Electrochemical Capacitors: Electrode Materials,Device Configuration,and Functions

With increasing demand for portable, flexible, and even wearable electronic devices, flexible energy storage systems have received increasing attention as a key component in this emerging field. Among the options, supercapacitors, commonly referred to as ultracapacitors or electrochemical capacitors, are widely recognized as a potential energy storage system due to their high power, fast charge/discharge rate, long cycling life‐time, and low cost. To date, considerable effort has been dedicated to developing high‐performance flexible supercapacitors based on various electrode materials; including carbon nanomaterials (e.g., carbon nanotubes, graphene, porous carbon materials, carbon paper, and textile), conducting polymers (e.g., polyaniline, polypyrrole, polythiophene), and hybrid materials. A brief introduction to the field is provided and the state‐of‐the‐art is reviewed with special emphasis on electrode materials and device configurations.     

Recent progress on performances and mechanisms of carbon dots for gas sensing

Carbon dots (CDs), as an attractive zero-dimensional carbon nanomaterial with unique photoluminescent merits, have recently exhibited significant application potential in gas sensing as a result of their excellent optical/electronic characteristics, high chemical/thermal stability, and tunable surface states. CDs exhibit strong light absorption in the ultraviolet range and tunable photoluminescence characteristics in the visible range, which makes CDs an effective tool for optical sensing applications. Optical gas sensor based on CDs have been investigated, which generally responds to the target gas by corresponding changes in optical absorption or fluorescence. Moreover, electrical gas sensor and quartz crystal microbalance sensor whose sensing layer involves CDs have also been designed. Electrical gas sensor exhibits an increase or a decrease in electrical current, capacitance, or conductance once exposed to the target gas. Quartz crystal microbalance sensor responds to the target gas with a frequency shift. CDs greatly promote the absorption of the target gas and improve the sensitivity of both sensors. In this review, we aim to summarize different types of gas sensors involving CDs, and sensing performances of these sensors for monitoring diverse gases or vapors, as well as the mechanisms of CDs in different types of sensors. Moreover, this review provides the prospect of the potential development of CDs based gas sensors.     

A Comprehensive Review on Controlling Surface Composition of Pt‐Based Bimetallic Electrocatalysts

With increasing energy demands worldwide, significant efforts have been made to develop superior electrocatalysts for efficient energy conversion systems. Among all the electrocatalysts exploited, Pt‐based bimetallic nanomaterials stand out by virtue of their high catalytic activity and relatively low cost due to the introduction of a nonprecious metal component. It should be noted that electrocatalytic reactions only take place on the surface of catalysts, so investigations of the surface composition of Pt‐based bimetallic nanomaterials are necessary for practical electrocatalysts. In this review, recent studies on controlling the surface composition of Pt‐based bimetallic catalysts for the oxygen reduction reaction, formic acid electrooxidation, and ethanol electrooxidation are summarized. The controlling strategies, including the chemical method and the electrochemical method, are discussed. The impacts of surface composition compositions on the electrocatalytic performance are also discussed. Finally, the challenges and future directions for controlling the surface composition of Pt‐based bimetallic nanomaterials are addressed.     

Hierarchical Structures Based on Two‐Dimensional Nanomaterials for Rechargeable Lithium Batteries

Two‐dimensional (2D) nanomaterials (i.e., graphene and its derivatives, transition metal oxides and transition metal dichalcogenides) are receiving a lot attention in energy storage application because of their unprecedented properties and great diversities. However, their re‐stacking or aggregation during the electrode fabrication process has greatly hindered their further developments and applications in rechargeable lithium batteries. Recently, rationally designed hierarchical structures based on 2D nanomaterials have emerged as promising candidates in rechargeable lithium battery applications. Numerous synthetic strategies have been developed to obtain hierarchical structures and high‐performance energy storage devices based on these hierarchical structure have been realized. This review summarizes the synthesis and characteristics of three styles of hierarchical architecture, namely three‐dimensional (3D) porous network nanostructures, hollow nanostructures and self‐supported nanoarrays, presents the representative applications of hierarchical structured nanomaterials as functional materials for lithium ion batteries, lithium‐sulfur batteries and lithium‐oxygen batteries, meanwhile sheds light particularly on the relationship between structure engineering and improved electrochemical performance; and provides the existing challenges and the perspectives for this fast emerging field.