The dawn of a new era in optoelectronic technologies has emerged with the recent development of the organic inorganic hybrid halide perovskite. Its exceptional attributes, including high carrier mobility, an adjustable spectral absorption range, tong diffusion lengths, and the simplicity and affordability of fabrication render it one of the most exceptional and market-competitive optoelectronic materials for applications in photovoltaics, light emitting diodes (LED), photodetectors, lasers, and more. Moreover, its versatility in device architecture and ability to achieve relatively high performance devices via various processing techniques makes perovskites a highly promising material for various practical applications. Here, we review the organic inorganic hybrid halide perovskite and delve into its recent progress and relevant applications. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/
High energy lithium ion batteries are in demand for consumer electronics, electricdrive vehicles and grid-scale stationary energy storage. Si is of great interest since it has 10 times higher specific capacity than traditional carbon anodes. However, the poor cyclability due to the large volume change of Si upon insertion and extraction of lithium has been an impediment to its deployment. This review outlines three fundamental materials challenges associated with large volume change, and then shows how nanostructured materials design can successfully address these challenges. There have been three generations of nanostructure design, encompassing solid nanostructures such as nanowires, hollow nanostructures, and clamped hollow structures. The nanoscale design principles developed for Si can also be extended to other battery materials that undergo large volume changes. (c) 2012 Elsevier Ltd. All rights reserved.
Carbon dots represent an emerging class of fluorescent materials and provide a broad application potential in various fields of biomedicine and optoelectronics. In this review, we introduce various synthetic strategies and basic photoluminescence properties of carbon dots, and then address their advanced in vitro and in vivo bioapplications including cell imaging, photoacoustic imaging, photodynamic therapy and targeted drug delivery. We further consider the applicability of carbon dots as components of light emitting diodes, which include carbon dot based electroluminescence, optical down-conversion, and hybrid plasmonic devices. The review concludes with an outlook towards future developments of these emerging light-emitting materials. (C) 2014 Elsevier Ltd. All rights reserved.
Fluorescent metal nanoclusters (NCs) as a new class of fluorophores have attracted more and more attention due to their unique electronic structures and the subsequent unusual physical and chemical properties. The size of metal NCs approaches the Fermi wavelength of electrons, between metal atoms and nanoparticles, resulting in molecule-like properties including discrete energy levels, size-dependent fluorescence, good photostability and biocompatibility. These excellent properties make them ideal fluorescent probes for biological application. Up to now, significant efforts have been devoted to the synthesis, property and application studies of gold and silver NCs. Recently, a growing number of studies on copper and other metal clusters have also been reported. In this review article, we focus on summarizing recent advances in controllable synthesis strategies, chemical and optical properties, and sensing and imaging applications of metal NCs (mainly including Au, Ag, Cu, etc.). Finally, we conclude with a look at the future challenges and prospects of the future development of metal NCs. (C) 2014 Elsevier Ltd. All rights reserved.
Silver nanoparticles constitute a very promising approach for the development of new antimicrobial systems. Nanoparticulate objects can bring significant improvements in the antibacterial activity of this element, through specific effect such as an adsorption at bacterial surfaces. However, the mechanism of action is essentially driven by the oxidative dissolution of the nanoparticles, as indicated by recent direct observations. The rote of Ag+ release in the action mechanism was also indirectly observed in numerous studies, and explains the sensitivity of the antimicrobial activity to the presence of some chemical species, notably halides and sulfides which form insoluble salts with Ag+. As such, surface properties of Ag nanoparticles have a crucial impact on their potency, as they influence both physical (aggregation, affinity for bacterial membrane, etc.) and chemical (dissolution, passivation, etc.) phenomena. Here, we review the main parameters that will affect the surface state of Ag NPs and their influence on antimicrobial efficacy. We also provide an analysis of several works on Ag NPs activity, observed through the scope of an oxidative Ag+ release. (C) 2015 Elsevier Ltd. All rights reserved.
Recent advances in nanotechnology have given rise to a new class of fluorescent labels, fluorescent metal nanoclusters, e.g., Au and Ag. These nanoclusters are of significant interest because they provide the missing link between atomic and nanoparticle behavior in metals. Composed of a few to a hundred atoms, their sizes are comparable to the Fermi wavelength of electrons, resulting in molecule-like properties including discrete electronic states and size-dependent fluorescence. Fluorescent metal nanoclusters have an attractive set of features, such as ultrasmall size, good biocompatibility and excellent photostability, making them ideal fluorescent labels for biological applications. In this review, we summarize synthesis strategies of water-soluble fluorescent metal nanoclusters and their optical properties, highlight recent advances in their application for ultrasensitive biological detection and fluorescent biological imaging, and finally discuss current challenges for their potential biomedical applications. (C) 2011 Elsevier Ltd. All rights reserved.
In recent years, a large amount of focus has been given to the development of alternative energy sources that are clean and efficient; among these, electrochemical energy holds potential for its compatibility with solar and wind energy, as well as their applications in fuel cells, and metal-air batteries, and water electrolyzers. However, these technologies require the use of highly active and stable catalysts to make these applications feasible. Current catalysts consist of precious metals such as platinum and iridium, which are expensive and block common access to electrochemical energy. Transition metals, and their oxides, serve as a promising alternative to these precious metals. due to their intrinsic activity and sufficient stability in oxidative electrochemical environments. Among wide range of these metals, cobalt, manganese, nickel, and iron, have been extensively explored as bifunctional catalysts, capable of simultaneously catalyzing oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for energy storage and conversion. Not only do they show innate electrochemical capabilities, but their structural diversity, as well as their ability to be mixed, doped, and combined with other materials such as graphene, make transition metal oxides a highly attractive subject in electrochemical and materials research. This review serves to summarize the research currently available concerning transition metal oxides, and their applications as a bifunctional catalyst for the utilized fuel cells and rechargeable metal-air batteris in alkaline media. Particularly, oxide synthesis and their structural properties are related to their electrochemical abilities, along with their behavior when introduced to other catalytic materials and dopants. (C) 2016 Elsevier Ltd. All rights reserved.
In this article we review the development, current status and future prospects of nano- and microscale motors propelled by locally generated fields and chemical gradients. These motors move autonomously in fluids by converting different sources of energy into mechanical work. Most commonly they are particles that are similar in their largest dimensions to bacteria (a few microns) or eukaryotic cells (10-20 mu m). Their shapes and compositions are designed to break symmetry in some way to create a local gradient (chemical, acoustic, thermal, etc.). A few important principles are introduced for readers to understand the physics of powered movement on small length scales. Interesting collective and emergent behaviors, as well as current and developing applications of these motors are also reviewed. Nano- and micromotors that are propelled by other mechanisms such as bubble recoil and magnetic induction are also briefly discussed. (C) 2013 Elsevier Ltd. All rights reserved.
High performance lithium batteries are in great demand for consumer electronics, electric vehicles and grid scale stationary energy storage. Transition metal sulfides based on conversion or alloying reactions have drawn much attention because of their significantly higher specific capacity than traditional insertion electrode materials. However, their poor cyclability caused by the large volume change during the lithium (Li) up-taking and extraction has hindered their further developments and applications in Li rechargeable batteries. This review outlines the fundamental mechanisms and obstacles of the transition metal sulfides associated with Li storage through conversion reaction and also discusses how the nanostructure design can successfully address their challenges. Recent progresses in the nanoparticte synthesis, nanostructure design, composite fabrication, and their effects on the electrochemical performances are summarized and discussed. In addition, remaining challenges and possibilities for further improvements are also prospected. (C) 2014 Elsevier Ltd. All rights reserved.
During recent years there has been much interest in the use of nanoparticles for in vitro studies as well as for delivery of drugs and contrast agents in animals and humans. To this end it is necessary to increase our understanding of how these particles are taken up and transported within the cells, and to which extent they are metabolized and secreted. In this review we discuss the possibilities, challenges and pitfalls of studying endocytic pathways involved in cellular uptake of nanoparticles. Thus, the use of pharmacological inhibitors, expression of mutated proteins, use of siRNAs and colocalization experiments in such studies are critically evaluated. Although the main focus is on cellular uptake, also aspects of intracellular transport, recycling of nanoparticles to the cell exterior, disturbance of cellular functions, and metabolism of nanoparticles are discussed. (C) 2011 Elsevier Ltd. All rights reserved.
Biodegradable polymeric micelles have emerged as one of the most promising platforms for targeted and controlled anticancer drug delivery due to their excellent biocompatibility, prolonged circulation time, enhanced accumulation in tumor, and in vivo degradability. Notably, several micellar anticancer drugs, with clear advantages of decreased side effects and improved drug tolerance, have advanced to different phases of clinical trials. The therapeutic outcomes are, however, far from optimal, due to issues of low in vivo stability, poor tumor penetration, inefficient cellular uptake, slow intracellular drug release, etc. This review high-lights recent developments in functional biodegradable micelles for safe and efficient cancer chemotherapy. (c) 2012 Elsevier Ltd. All rights reserved.
Recent years have seen the rocket rise of graphene as the unique two-dimensional carbon nanosheets and its outstanding promise in materials science. In particular, because of its diverse, tunable structural and electronic properties, graphene has been well recognized to be an ideal co-catalyst to optimize the photocatalytic performance of semiconductors. Given that the conductive, optical, chemical and mechanical performances of graphene are closely linked to its structural diversity, tremendous efforts have been devoted to designing and tailoring the graphene nanosheets to construct the desirable architecture. The tailored graphene materials (GMs), such as zero-dimensional graphene quantum dots, one-dimensional graphene nanoribbons and three-dimensional graphene frameworks show a variety of fascinating features, thereby offering a fertile and flexible ground for the further development of GMs enhanced photocatalysis. This review aims to provide an overview on the structural diversity, tunable properties, and synthetic strategies of these GMs, followed by highlighting their multi-functionality in heterogeneous photocatalysis. Finally, the perspectives on future research trends and challenges in constructing more efficient GMs-enhanced systems for solar energy conversion are presented. The integral comprehension of GMs with all dimensions would further guide the fundamental processing-structure-properties-applications relationships of GMs. (C) 2016 Elsevier Ltd. All rights reserved.
Polymeric micelles (PM) are extensively used to improve the delivery of hydrophobic drugs. Many different PM have been designed and evaluated over the years, and some of them have steadily progressed through clinical trials. Increasing evidence suggests, however, that for prolonged circulation times and for efficient EPR-mediated drug targeting to tumors and to sites of inflammation, PM need to be stabilized, to prevent premature disintegration. Core-crosslinking is among the most popular methods to improve the in vivo stability of PM, and a number of core-crosslinked polymeric micelles (CCPM) have demonstrated promising efficacy in animal models. The latter is particularly true for CCPM in which (pro-) drugs are covalently entrapped. This ensures proper drug retention in the micelles during systemic circulation, efficient drug delivery to pathological sites via EPR, and tailorable drug release kinetics at the target site. We here summarize recent advances in the CCPM field, addressing the chemistry involved in preparing them, their in vitro and in vivo performance, potential biomedical applications, and guidelines for efficient clinical translation.
Phagocytes are key cellular participants determining important aspects of host exposure to nanomaterials, initiating clearance, biodistribution and the tenuous balance between host tolerance and adverse nanotoxicity. Macrophages in particular are believed to be among the first and primary cell types that process nanoparticles, mediating host inflammatory and immunological biological responses. These processes occur ubiquitously throughout tissues where nanomaterials are present, including the host mononuclear phagocytic system (MPS) residents in dedicated host filtration organs (i.e., liver, kidney spleen and lung). Thus, to understand nanomaterials exposure risks it is critical to understand how nanomaterials are recognized, internalized, trafficked and distributed within diverse types of host macrophages and how possible cell-based reactions resulting from nanomaterial exposures further inflammatory host responses in vivo. This review focuses on describing macrophage-based initiation of downstream hallmark immunological and inflammatory processes resulting from phagocyte exposure to and internalization of nanomaterials. (C) 2015 Elsevier Ltd. All rights reserved.
Nobel metal nanomaterials (NMNs) with interesting physical and chemical properties are ideal building blocks for engineering and tailoring nanoscale structures for specific technological applications. Particularly, effectively controlling the size, shape, architecture, composition, hybrid and microstructure of NMNs plays an important role on revealing their new or enhanced functions and application potentials such as fuel cell and analytical sensors. This review article focuses on recent advances on controllable synthesis and fuel cell and sensing applications of NMNs. First, recent contributions on developing a wet-chemical approach for the controllable synthesis of noble metal nanomaterials with a rich variety of shapes, e.g. single-component Pt, Pd, Ag and Au nanomaterials, multi-component core/shell, intermetallic or alloyed nanomaterials, metal fluorescent nanoclusters and metal nanoparticles-based hybrid nanomaterials, are summarized. Then diversified approaches to different types of NMNs-based nanoelectrocatalysts with the aim to enhance their activity and durability for fuel cell reactions are outlined. The review next introduces some exciting push in the use of NMNs as enhanced materials or reporters or labels for developing new analytical sensors including electrochemical, colorimetric and fluorescent sensors. Finally, we conclude with a look at the future challenges and prospects of the development of NMNs. (C) 2011 Elsevier Ltd. All rights reserved.
In recent years, the emerging fluorescent carbon dots have shown enormous potentials for biomedical and optoelectronic applications owing to their outstanding characteristics such as good biocompatibility, low cytotoxicity, photostability and versatility in addition to their unique tunable photoluminescence and other exceptional physicochemical properties. In this review, we will update the latest researches on the synthesis, structure, optical and electronic properties of CDs as well as their advanced applications in biomedicine and optoelectronics. We will mainly discuss the applications of CDs in bioimaging with emphasis on stem cells imaging including normal and cancer stem cells, cell nucleus imaging, two-photon fluorescence imaging, red or near-infrared emission for in vivo imaging, cancer therapy including photodynamic therapy, photothermal therapy and chemotherapy, and optoelectronic applications including light emitting diodes and solar energy conversion. Finally, we will size up current challenges on the research of CDs and project future directions of the field. We hope that this review will provide critical insights to inspire new exciting discoveries on CDs from both fundamental and practical standpoints so that the realization of their potential in the biomedical and optoelectronic areas can be facilitated. (C) 2016 Elsevier Ltd. All rights reserved.
Nanotechnology opens a door to tailing materials and creating various nanostructures for use in dye-sensitized solar cells. This review classifies the nanostructures into (1) nanoparticles, which offer large surface area to photoelectrode film for dye-adsorption, (2) core shell structures, which are derived from the nanoparticles however with a consideration to reduce charge recombination by forming a coating layer, (3) one-dimensional nanostructures such as nanowires and nanotubes, which provide direct pathways for electron transport much faster than in the nanoparticle films, and (4) three-dimensional nanostructures such as nanotetrapods, branched nanowires or nanotubes, and oxide aggregates, which not only emphasize providing large surface area but also aim at attaining more effective light harvesting and charge transport or collection. The review ends with an outlook proposing that the oxide aggregates are a potentially promising structure which may possibly achieve higher efficiency than the record by reason that the bifunction of aggregates in providing large surface area and generating light scattering allows for photoelectrode film thinner than usual and thus decreases the charge recombination of DSCs. (C) 2010 Elsevier Ltd. All rights reserved.
Reliable and cost-effective technologies for electrical energy storage are in great demand in sectors of the global economy ranging from portable devices, transportation, and sustainable production of electricity from intermittent sources. Among the various electrochemical energy storage options under consideration, rechargeable lithium sulfur (Li-S) batteries remain the most promising platform for reversibly storing large amounts of electrical energy at moderate cost set by the inherent cell chemistry. The success of Li-S storage technology in living up to this promise calls for solutions to fundamental problems associated with the inherently low electrical conductivity of sulfur and sulfides, and the complex solution chemistry of lithiated sulfur compounds in commonly used electrolytes. These problems appear well posed for innovative solutions using nanomaterials and for fundamental answers guided by the tools of nanotechnology. Beginning with a review of the current understanding of Li-S battery chemistry and operation, this review discusses how advances in nano-characterization and theoretical studies of the Li-S system are helping advance the understanding of the Li-S battery. Factors that prevent Li-S cells from realizing the theoretical capacity set by their chemistry are discussed both in terms of the impressive advances in cell design enabled by nanomaterials and recent progress aimed at nanoengineering the cathode and other cell components. Perspectives and directions for future development of the Li-S storage platform are discussed based on accumulated knowledge from previous efforts in the field as well as from the accumulated experience of the writers of this review. (C) 2015 Elsevier Ltd. All rights reserved.
Graphene, carbon nanotubes, and fullerene are representative nanocarbons which have zero, one, or two dimensional structures, respectively. These nanocarbons can be used as building blocks for construction of higher dimensional or complex materials by nanoarchitectonics; a technology used to control nanoscale structures and spaces. By combination with other materials and/or devices, nanoarchitectures of nanocarbons can be formed into structures of different dimensions and properties for biological applications. In this review, biological applications, especially cell growth, sensing, and control using nanoarchitectures of nanocarbons are summarized. (C) 2014 Elsevier Ltd. All rights reserved.
Polymeric micelles provide a platform that can be carefully tuned for drug delivery. The nano-scale aggregates form spontaneously in aqueous solution and can be used to overcome drug insolubility and increase circulation half life. Self-assembled polymeric micelles are dynamic in nature; thermodynamics defines how the system acts as micelles approach equilibrium, while kinetics characterizes the system's behavior over time. In this review, we discuss factors that affect the stability of self-assembled polymeric micelle systems for drug delivery and methods used to study stability. Considerations of polymer composition, drug encapsulation, and environmental conditions influence polymeric micelle stability. Ultimately, we emphasize the importance of investigating micelle systems in physiologically relevant media to improve therapeutic efficacy and reduce systemic toxicity in clinical applications. (C) 2012 Elsevier Ltd. All rights reserved.