摘要:

Introducing the inaugural Editorial BoardOne of the key support structures ofNanoscaleis the Editorial Board. We have brought together a vibrant group of high-calibre scientists from a range of scientific backgrounds and geographical regions to join the three Editors-in-chief, Professors Chunli Bai, Markus Niederberger and Francesco StellacciChunli Bai,Editor-in-Chief, Asia-PacificMarkus Niederberger,Editor-in-Chief, EuropeFrancesco Stellacci,Editor-in-Chief, North America• Professor Lennart Bergström, Stockholm University, Sweden, who works on synthesizing and assembling inorganic materials into challenging and useful structures and compositions.• Professor Claus Feldmann, Karlsruhe University, Germany, whose research focuses on the synthesis, analytical characterization and investigation of functional nanomaterials.• Professor Sharon Glotzer, University of Michigan, USA, who uses computer simulation to understand the fundamental principles of how a wide range of nanoscale systems self-assemble.• Professor Xingyu Jiang, National Center for Nanoscience and Technology, Beijing, China, who works on nanosystems for biomedical applications.• Professor Molly Stevens, Imperial College London, UK, who works on exploiting specific biomolecular recognition and self-assembly mechanisms to create new dynamic nanomaterials, biosensors and drug delivery systems.• Professor Dmitri Talapin, University of Chicago, USA, who uses colloidal synthesis, self-assembly and characterization of nanomaterial properties to create novel materials for electronic, photovoltaic, thermoelectric and catalytic applications.• Professor G. Julius Vancso, University of Twente, The Netherlands, whose research focuses on the molecular-level understanding, manipulation and control of polymeric materials.In addition, we are delighted to introduce Professor Jianfang Wang from the Department of Physics at The Chinese University of Hong Kong as Associate Editor ofNanoscale. Prof. Wang graduated from the University of Science and Technology of China in 1993 and received his MSc and PhD degrees from Peking University (1996) and Harvard University (2002), respectively.Jianfang Wang,Associate Editor

ISSN:2040-3364    

DOI:10.1039/b925449h

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

1.IntroductionHydrogen energy is showing promise as clean energy for future applications. However, since hydrogen gas is odorless, colorless and highly inflammable, safety becomes a primary concern. Hydrogen concentration in excess of 4 vol% in ambient air is potentially explosive.1,2Thus, the necessity of hydrogen sensors for leak detection as well as H2line feed monitoring arises. Measurable response to hydrogen and room temperature operating conditions are some of the prerequisites for good hydrogen sensing materials. Noble metal and metal oxide based sensors are already in the market.3,4While the metal oxide sensors have the drawback of elevated operating temperatures, the bulk Pd and Pt based sensors, though very efficient, are expensive. This problem is circumvented by using nano sized powders, films or by depositing these particles on other nanostructures with larger surface area. In this context, carbon based nanostructured materials can be highly useful due to their large surface area and high electrical conductivity.Carbon based nanostructured materials, especially the one dimensional carbon nanotubes5and of late even the two dimensional graphene6have been of tremendous scientific and technological interest due to their unique physical and chemical properties.7,8The electronic properties of the multi walled carbon nanotubes (MWNT) are governed mainly by the outermost layer which is also chemically very active. In addition, their 1D nature gives them a large surface area. Graphene, on the other hand is a planar sheet of graphitic carbon wherein the carbon atoms are tightly arranged in a 2D honeycomb like lattice. Graphene sheets have extremely large surface areas, approximately 2 times that of MWNT. Moreover, exceptionally high electron mobilities at room temperatures have been reported for multi layer graphene, with values in excess of 10 000 cm2V−1s−1. More importantly, both these carbon nanostructures can be engineered to detect suitable gases by the introduction of defects and functional groups, thus making them suitable candidates for gas sensing applications. It is known that Pt is a very good material for H2sensing because Pt dissociates H2molecules in to H atoms. Due to their large surface area, the carbon nanostructures are used as support materials for dispersing of Pt nanoparticles uniformly on surfaces mainly to reduce the Pt content. In addition, carbon nanotubes and graphene are highly conducting materials which will enhance the detection of the change in the electrical properties due to adsorption of hydrogen.With these things in view, the current work focuses on developing room temperature hydrogen gas sensors based on Pt decorated functionalized graphene sheets (Pt/f-G) and Pt decorated functionalized multi walled carbon nanotubes (Pt/f-MWNT). Keeping large scale applications in view, we have employed a simple drop casting technique for the fabrication of these sensors. The Pt/f-MWNT sensor prepared this way shows a performance comparable to a spin coated Pt/f-MWNT sensor reported by us in an earlier work,9thus justifying the procedure. Additionally, for flow monitoring of hydrogen gas as in hydrogen fuel stations, hydrogen pipelinesetc.detection of large volumes of gas becomes necessary. Hence the detection levels were maintained in terms of volume %.

ISSN:2040-3364    

DOI:10.1039/b9nr00015a

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

1.IntroductionThe application of nanotechnology to the treatment of degenerative diseases – their diagnosis, their monitoring, and their control – has garnered attention in recent years. More specifically, research into the targeting and delivery of diagnostic, therapeutic, and pharmaceutical agents is right at the forefront of nanomedicine as scientists and engineers strive, along with physicians, to meet a long list of requirements from the laboratory to the pharmacy. Presently, drug delivery systems are being designed to alter the pharmacokinetics and pharmacodynamics of the drugs they deliver, as well as to function as reservoirs for the drugs themselves. The majority of drug delivery systems currently approved by the Food and Drug Administration (FDA), fall either into the category of liposomal, lipid-based formulations or into the collection of therapeutic compounds that are linked in some way to polyethyleneglycol (PEG). The mechanised silica nanoparticles (MSNPs), which will be brought into the spotlight in this review, offer a fresh approach to drug delivery, which combines the robustness of the drug delivery vehicle with the preciseness of molecular machinery.Some of the nanotechnologies that can be accessed with MSNPs, which range in diameter from approximately 50 to 200 nm, are illustrated inFig. 1. The molecular machinery on the surfaces of the silica nanoparticles (SNPs) falls broadly into two categories – that is, molecular on the right-hand side, and supramolecular on the left-hand side. While the latter are much easier to come by synthetically than the former, their operation is irreversible. On the other hand, the molecular nanovalves lend themselves to robustness in addition to being much more amenable to precise control than the supramolecular ones. The difference is that, while the former behave like [2]rotaxanes – where one of the stoppers on the dumbbell component is the SNP itself – the latter are more akin to semirotaxanes – that is, they are pseudorotaxanes with one stopper which is once again the SNP. Two different types of molecular nanovalves have been identified and investigated: in one type, the covalent rupture of the terminal stoppers allows the rings to forsake their recognition sites and depart from the stalks. This process can be likened to a beverage can with a snap-top,i.e., break it once, for example, by the enzymatic cleavage of a particular covalent bond and then the ring will depart from the stalk, followed immediately thereafter by the spilling out of the cargo. The other molecular type is based on switchable bistable [2]rotaxane molecules where, under redox or pH control, for example, the ring can be switched from one recognition site to the other andvice versa. By contrast, in the supramolecular varieties of nanovalves, there are no stoppers and so the rings owe their association with the stalks to a single strong binding site which can be modified, such as to kill the binding interactions, thus permitting the rings to depart from the stalks. In addition to enzyme activation of the molecular machinery, situations involving light-activation, or changes in pH, to bring about the activation of acid- and base-responsive nanovalves have all been harnessed. It should be stressed that these are only some of the possible nanotechnologies that can be assessed: there are more!Top: A graphical representation of the mechanised silica nanoparticle-based technologies highlighted in this review. Mesoporous SNPs, in particular MCM-41, provide an outstanding platform on which molecular machinery, be it supramolecular or molecular in nature, can be attached to the surfaces of the SNPs. Bottom: The range of containers and machines that compete today in the arena of drug delivery systems.In this review, we will highlight the molecular machinery, which can be incorporated onto the surfaces of silica mesostructures to make MSNPs, and the different release mechanisms employed to unload the cargo on demand. We begin by discussing how silica thin films and nanoparticles are synthesised, functionalised with organic and metallic substrates, as well as how to assess the SNPs' cellular uptake and cytotoxicity as a result of investigations conducted on mammalian cell lines. Following these discussions, the incorporation of supramolecular and molecular machinery – such as [2]pseudorotaxanes and [2]rotaxanes nanovalves – into MSNPs, will be reviewed. This exploration is followed by the introduction of various snap-top MSNP systems which are activated by chemical or light stimulus. We conclude by reviewing the progress being made in making MSNPs more biocompatible as a result of introducing semirotaxanes as the nanovalves which incorporate water-soluble cyclodextrin and cucurbit[n]uril rings.

ISSN:2040-3364    

DOI:10.1039/b9nr00162j

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

Dr Jing ZhangDr Jing Zhang was born in 1979. He received his PhD in Physical Chemistry in 2007 under the supervision of Prof. Zhang Lin with a thesis on "Nanocrystal Growth Kinetics Controlled by the Surface Adsorption Effect". Currently, he works as a post-doctoral researcher in the Soft Matter Group of the Solid State Research Institute in the Forschungszentrum Juelich, Germany, where he investigates nonionic water-in-oil microemulsions and their effects on the nucleation and growth of nanocrystals.

ISSN:2040-3364    

DOI:10.1039/b9nr00047j

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

1.IntroductionPeripheral nerve injuries often result from acute trauma and may lead to chronic sensorimotor defects due to the lack of a successful and robust reparative technique.1Clinically, the typical procedures for repairing injured peripheral nerves are based upon either direct coaptation of the transected nerve stumps (in the case of small nerve defects) or the use of nerve grafts (in the case of large nerve defects).2For autografting that involves the harvest of a donor nerve from the patient and transplantation into the defect site, it can often yield superior functional recovery. The procedure, however, tends to be impaired by a number of drawbacks such as loss of function at the donor site, limited availability of donor nerves, size mismatch between the donor and recipient nerves, and the need for multiple surgeries.3As an alternative, allografts (i.e., nerves harvested from other human being or animal) can be employed, but patients are at a risk of immuno- and disease-related complications. As a result, there exists an imperative need for the development of artificial nerve guidance conduits (NGCs), which can potentially overcome the limitations associated with nerve autografts and allografts.Many types of NGCs have been developed to facilitate axonal guidance and thus to enhance nerve regeneration; good examples include arrays of microchannels and microfilaments, fiber bundles, hollow fiber membranes, and multi-layered tubes.4These synthetic NGCs offer a range of advantages over nerve autografts and allografts, including improved availability, a wider range of size selection, no extra surgery to harvest the donor nerve, reduced axonal escape at the suture site, and the ability to stimulate and guide regenerating axons.5While most of these synthetic conduits have shown great promisein vitro, they are still challenged or limited by the inability to direct and enhance axonal regenerationin vivo.6In addition, synthetic NGCs are currently limited in supporting functional nerve regeneration across nerve defects beyond a critical length.6aIn general, NGCs are incapable of selectively guiding motor and sensory axons toward the appropriate end organs. Thus, only a limited percentage of the regenerated fibers is able to re-innervate the desired motor or sensory targets. Most of the fabricated conduits to date are also troubled by a rigid structure with limited flexibility, which may impair intraoperative handling and make it very difficult to implant the devices.7To this end, a new class of NGCs based upon electrospun nanofibers may have the potential to overcome some of the limitations associated with traditional NGCs.Owing to the small feature size, a nonwoven mat derived from electrospun nanofibers typically exhibits a high porosity and large surface area. These features enable a nanofiber-based scaffold to closely mimic the hierarchical structure of the extracellular matrix (ECM), an environment critical for cell attachment/migration, signal transduction, and nutrient transport.8aNanofibers can also be functionalizedviaencapsulation or attachment of bioactive molecules such as native ECM proteins and nucleic acids to potentially guide both the differentiation and proliferation of cells seeded on the scaffold. In addition, electrospun nanofibers can be readily aligned into uniaxial arrays. The resulting anisotropic material properties have been shown to be an effective cue to direct and enhance neurite outgrowth, providing a major advantage over other isotropic materials such as hydrogels or nonwoven fibrous structures. By manipulating their morphology, alignment, stacking, and/or folding, the electrospun nanofibers can be assembled into a large number of hierarchically structured scaffolds or conduits. All these attributes make electrospun nanofibers an intriguing class of materials for neural tissue engineering.8This feature article reviews the recent progress on the application of electrospun nanofibers to neural tissue engineering. We illustrate how to control the alignment and morphology of electrospun nanofibers and to fabricate novel NGCs from nanofibers. A major emphasis is placed on highlighting the potential of electrospun nanofibers for manipulating stem cell differentiation, guiding and promoting neurite outgrowth, and ultimately serving as NGCs for peripheral nerve injury repair.

ISSN:2040-3364    

DOI:10.1039/b9nr00243j

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

AFM: blindly probing surfaces may not be enoughDeprived of our eyesight, we humans sense the objects around us with the aid of our hands or sticks. In this way we get an idea about objects' size, their shape, their texture and their hardness. As we step forward, weintuitivelyprobe our immediate environment by systematically moving our hands or swinging a stick to the left and right, and up and down. We register thepositionof an obstacle and we follow its contours by just sliding or tapping our fingertips over its surface.The atomic force microscope certainly resembles the human analog as a blind microscope that can sense micro-and nano-objects (Fig. 1). Indeed, the instrument provides the probingstick, a microsized cantilever with a tip at its free end; a piezodriven device to move the probe over the sample (orvice versa) in three dimensions with nanometre precision; a means to get the tip position during its movement and a feedback mechanism to control how strongly the tipslidesortapsover the sample surface. In this way, atomic force microscopy (AFM) has become an invaluable technique to explore the morphology of the nanoworld. Moreover, since the cantilever is a force transducer, it has been extensively used to study surface and molecular interactions.AFM imaging basics as a blind microscope analog. By blindly inspecting an object just underneath we systematically move our body and stick right and left, and up and down. We can either slide or tap our stick over the surface. Our brain controls the movement and the force we exert on the surface through our hand and stick. AFM resembles the analog with a cantilever as anelastic stick, a piezoscanner that moves it along three dimensions, a laser, and a position detector that registers its position. The ways the tip can scan the surface are more numerous than we humans have, however, on most occasions the tip is either made to slide over the surface, impinging a defined force (contact mode imaging) or to tap the sample more or less gently (intermittent contact imaging). The operation is electronically controlled to ensure the scanning is being executed under the desired scan conditions. Finally, a computer processor presents the result as an image. (Fromref. 31).In spite of its many advantages, the atomic force microscope as a stand-alone tool retains some limitations. Spectroscopic identification is beyond its reach, as are determination of contact areas or absolute distances between probe and sample. Combining the atomic force microscope with complementary techniques to build hybrid instrumentation promises more than one way to overcome these limitations. Synergy may result from such combinations. Optical microscopy bestows on AFM theeyesfor precise tip positioning in microstructured materials or cells; interferometry confers the capability of measuring absolute distances, and Raman spectroscopy, the label-free chemical identification of species. Reciprocally, AFM coupled with model-based techniques such as ellipsometry, surface plasmon resonance or even quartz crystal microgravimetry is of invaluable assistance in model validation, the calculation of adsorbed mass, the estimation of trapped solvent or assessing the effect of sample heterogeneity. We will briefly summarize the state-of-the-art developments of such combined techniques.

ISSN:2040-3364    

DOI:10.1039/b9nr00156e

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

Poulomi RoyPoulomi Roy received her MSc degree in Inorganic Chemistry from Vidyasagar University, India and obtained her PhD degree in Inorganic Nanomaterials from the Indian Institute of Technology, Kharagpur, in 2007. She joined the group of Prof. Patrik Schmuki at the University of Erlangen–Nürnberg, Germany in 2008 as a post-doctoral fellow, where currently she is continuing her research. Her research interests include the synthesis of semiconductor nanomaterials and their application in various energy fields, especially in solar cells.

ISSN:2040-3364    

DOI:10.1039/b9nr00131j

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

Ms Xiaowaei XieMs Xiaowei Xie is a PhD candidate at Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Her research topic is fabrication and characterization of morphology-controlled Co3O4nanocrystals and their applications in CO oxidation at low temperatures dating from 2004. Her experience includes design and synthesis of metal oxide nanomaterials, structure analysis and catalytic reaction chemistry.

ISSN:2040-3364    

DOI:10.1039/b9nr00155g

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

Malti BansalMalti Bansal received her BSc (Honours) Electronics Degree and MSc (Electronics) Degree from the University of Delhi, India in 2003 and 2005 respectively. Subsequently she was awarded a research fellowship from the Netaji Subhas Institute of Technology, India. She worked on the synthesis and characterization of silicon carbide nanomaterials and their applications in the field of nanocomposites. In May 2007, she started her Doctoral work in the field of carbon nanotubes and is currently pursuing the same at the National Physical Laboratory, India and the Netaji Subhas Institute of Technology, India. Her current research interests include synthesis of carbon nanotubes, their characterization and applications in the field of macroelectronics and nanoelectronics.

ISSN:2040-3364    

DOI:10.1039/b9nr00179d

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

IntroductionEmergence of novel nanoparticles, namely colloidal particles of 5–50 nm in diameter, such as semiconductor nanocrystal and metallic nanoparticles, has fundamentally changed the bioanalytical measurement landscape.1–4Luminescent semiconductor nanocrystals, colloquially known as quantum dots (QDs), stand among the research tools in chemistry, physics, and biology as one of the most exciting developments. These inorganic fluorescent nanocrystals typically comprise periodic groups ofii–vi(e.g.CdSe and CdTe) oriii–v(e.g.InP and InAs) semiconductor materials. As a photon of proper energy impinges a semiconductor, exciting an electron from the valence band into the conduction band, it generates an electron–hole pair (or exciton) that is weakly bound by Coulomb forces. For semiconductor nanocrystals with all three dimensions less than the Bohr exciton radius (typically a few nanometres), their energy levels are quantized (due to quantum-confinement effect, henceforth named quantum dots), and the spacing of which can be controlled by the crystal sizes.5,6This effect leads to the superior optical properties of QDs, such as narrow, symmetric and size-tunable emission spectra, and broad excitation spectra, rendering them particularly valuable for multicolor fluorescent applications. Other commonly discussed benefits of QDs over organic fluorophores or fluorescent proteins include stronger fluorescence (∼10–100 times brighter) and higher fluorescence stability against photobleaching (∼100–1000 times more stable),7,8which facilitate the long-term monitoring of intermolecular and intramolecular interactions in live cells and organisms. Consequently, since the first demonstration of colloidal quantum dots for biological labeling in 1998,9,10subsequent innovations have centered on the exploration of QDs for biomedical applications.Synthesis and surface modification of quantum dotsAmong the array of synthetic routes devised for the preparation of quantum dots (reviewed inrefs. 8,11–16), the predominant approach is to coat a CdSe core with a ZnS layer to obtain the best crystalline quality and monodispersity. Passivation by the ZnS layer protects the core from oxidation, reduces toxicity by preventing the CdSe from leaching out to the surrounding solutions, and also enhances the photoluminescence yield. However, the ZnS-coated QDs are only soluble in nonpolar organic solvents. Due to the aqueous nature of the biological environment, altering the QD surface properties from hydrophobic to hydrophilic becomes an essential step for QDs to be useful in biological applications. Although the synthesis of QDs has been performed directly in aqueous solution, the products of the aqueous schemes are largely polydispersed and rarely match the quality of those synthesized through high-temperature routes with hydrophobic organic solvent/ligand mixtures.7,17,18Furthermore, inorganic materials such as QDs have little to no innate biological specificity. They must rely on conjugation with biological molecules such as aptamers,19antibodies,20oligonucleotides,21peptides,22–25folates,26and small molecule ligands to gain biological affinity.27After much effort to alter the properties of QDs, such as stability, monodispersity, crystallinity, solubility, and biocompatibility,9,20,28–30QDs have evolved from an interesting curiosity to a widely used research tool for diagnostics, cell and molecular biology studies, andin vivobioimaging.11,12,31QD-based multiplexed biosensing and FRETQuantum dots have become popular fluorescent cellular probes for light microscopy (LM), again because of their unique optical and physical properties. Notably, their electron-dense semiconductor cores can be directly imaged by electron microscopy (EM) even without any contrasting treatment.32Collectively, their distinct size, shape and elemental fingerprint facilitate multilabeling for correlative microscopy with LM and EM.33A widely adopted mechanism of QD-based fluorescence biosensing is through QD-mediated Förster Resonance Energy Transfer (FRET). Since the first theoretical predication and experimental demonstration,34,35respectable progress has been made in the past few years on the use of QD-FRET based biosensors,36,37particularly on bioanalysis (nucleic acids, proteins, and immunoassays) and intracellular sensing. QDs possess several unique optical properties over organic fluorophores that can benefit FRET configurations, including broad absorption, size-dependent narrow emission and strong resistance to photobleaching. Their emission spectra are usually fairly symmetric and narrow (typically 10–20 FWHM), tunable across a wide range by changing the size and composition of the QD core, once again due to the quantum confinement effect. When paired with an organic fluorophore, crosstalk, the spectrum overlap between the donor and acceptor emissions, can be effectively minimized. Meanwhile, the QD absorption has an increased probability at higher energies, resulting in a broader absorption over the entire spectral range extending from the characteristic emission band to the UV band. This feature enables the use of UV-range excitation, lessening the possibility of direct-acceptor excitation. Perhaps more importantly, excitation at a single wavelength can excite multiple QDs to emit in non-overlapping, narrow spectral ranges that can still be discriminated. This renders QDs well suited towards multicolor applications38,39and even mulitiplexed FRET, which would be particularly valuable for cellular interactions involving multiple entities or events.Nanoparticle-mediated cellular responsesDespite the tremendous therapeutic potential of nanoparticles in medicine, the fundamental information regarding the physicochemical interaction between nanoparticles and cells (i.e.membrane surfaces, endosomal compartments, cytoplasm, and other organelles) is relatively limited (recently reviewed inref. 40). Cellular uptake of nanoparticles is modulated by size,41shape and angle of curvature,42–44effective surface charge (zeta-potential) and surface functionalization.45For example, gold nanoparticles45and QD conjugates46exhibit different cell-membrane penetration and cytotoxicity characteristics depending on the types of ligand on their surfaces. It would be valuable to investigate whether there exists an intrinsic generalized correlation between the physicochemical properties of nanoparticles and cellular responses. Otherwise, findings for a particular nanomaterial, such as gold nanoparticles (currently the most studied because of their ease of synthesis and characterization), may be irrelevant for other types of nanomaterials (such as QDs), or even invalid for the same nanomaterial that is produced through a different synthetic route. For instance, why does the cytotoxicity of gold nanoparticles differ with size and surface decoration?42,47A better understanding of nanoparticle-mediated cellular responses, therefore, would assist nanoparticle design by providing insights on the uptake kinetics and intracellular behavior to complement the readout of therapeutic efficacy or marker gene expression levels.Scope of this mini reviewTheranostics, a term coined for combining diagnostics and therapeutics, integrates real-time evaluation with delivery of a medication. QDs excel in imaging applications; they may also serve as particulate delivery vehicles if the biocompatibility issue can be managed. Such multifunctional nanoparticles offer synergistic advantages over any single-modal nanoparticle alone.48–51Through surface immobilization of ligands and conjugation of “drugs” on QD one can construct an “all-in-one” multifunctional nanoplatform that features targeting, therapeuctic and imaging modalities. Multifunctional QDs therefore may have the potential to meet the requirements of a theranostic system, which ideally, should possess a number of the following characteristics (Fig. 1): (a) accumulate in the pathological zone, targeting specific cell types, (b) penetrate the cells efficiently, with minimal cytotoxicity, (c) overcome the intracellular delivery barriers, allowing efficient intracellular trafficking, (d) respond to local stimuli, releasing the therapeutic agents, and (e) bear a diagnostic agent (optical or magnetic), allowing for real-time monitoring of the treatment. Current success of QD-based theranostics remains at the stage ofex vivo, due to the challenges of navigating the biological barriersin vivoand imaging deep tissues. With respect to multifunctional nanoparticles constructed on metallic and magnetic nanoplatforms constructed from various types of nanoparticles, the readers are referred to two recent reviews.52,53In this mini review, we explore specifically whether multifunctional QDs would be able to tackle the challenges in theranostics. We will begin with coverage of QDs carrying single-function modalities, paying special attention to the emerging application of QDs for drug and gene delivery. We will then describe the integration of multiple-function modalities in highlighted examples to illustrate the potential and challenges of QD-based theranostics for future nanomedicine.(a) Schematic representation of a multimodal QD, where the QD serves as both a diagnostic agent (imaging) and a nanoscaffold to incorporate multiple functional modalities, such as a targeting ligand (peptide, antibody, or protein) and a therapeutic agent. Upon interacting with the target cell, the cell-penetrating ligand can then be exposed, allowing the multifunctional QD to enter the cell. Stimuli-sensitive antennae may be triggered by local stimuli (pH, temperature, or enzyme), allowing subsequent intracellular release of the drug from the drug-loaded vesicle. (b) Requirements of an ideal theranostic process in the human body may include: (1) escape from the clearance of reticuloendothelial system (RES, mainly liver, spleen, and bone marrow), allowing longer blood circulation time, (2) accumulate in the pathological zone, targeting specific cell types, (3) penetrate the cell efficiently, leaving minimum damage to the cell, (4) overcome the delivery barriers, leading to efficient intracellular release, and (5) bear a diagnostic agent (imaging, optical or magnetic), allowing for real-time monitoring of the treatment, while maintaining minimum toxicity to the healthy cells.

ISSN:2040-3364    

DOI:10.1039/b9nr00178f

出版商:RSC    

年代:2009

数据来源: RSC