Highly Integrated Supercapacitor-Sensor Systems via Material and Geometry Design.

An ultimate integration strategy making use of material and geometry is applied in a proof-of-concept study. Integrated supercapacitor-sensor systems with the capability of photodetecting and strain sensing are fabricated based on multifunctional conducting polypyrrole and piezoresistive textile geometry, respectively. This integration strategy enables promising applications for self-powered smart sensory, wearable and healthcare electronics.

Polyvinylpyrrolidone-assisted ultrasonic synthesis of SnO nanosheets and their use as conformal templates for tin dioxide nanostructures.

Single crystalline SnO nanosheets with exposed {001} facets have been prepared by an ultrasonic aqueous synthesis in the presence of polyvinylpyrrolidone, which hinders the spontaneous formation of the truncated bipyramidal SnO microcrystals and exfoliate them into layer-by-layer hierarchical structures and further into separate SnO nanosheets. The SnO nanosheets have been used as conformal sacrificial templates converted into polycrystalline SnO(2), as well as layered SnO/SnO(2) nanostructures, by calcination in air. The concept of fabrication of two-dimensional tin oxide nanostructures demonstrated here may be relevant for the crystal design of layered materials, in general.

Surface-biofunctionalized multicore/shell CdTe@SiO(2) composite particles for immunofluorescence assay.

Strongly fluorescent multicore/shell structured CdTe@SiO(2) composite particles of ∼ 50 nm were synthesized via the reverse microemulsion method by using CdTe quantum dots co-stabilized by thioglycolic acid and thioglycerol. The optical stability of the CdTe@SiO(2) composite particles in a wide pH range, under prolonged UV irradiation in pure water, or in different types of physiological buffers was systematically investigated. Towards immunofluorescence assay, both poly(ethylene glycol) (PEG) and carboxyl residues were simultaneously grafted on the surface of the silanol-terminated CdTe@SiO(2) composite particles upon further reactions with silane reagents bearing a PEG segment and carboxyl group, respectively, in order to suppress the nonspecific interactions of the silica particles with proteins and meanwhile introduce reactive moieties to the fluorescent particles. Agarose gel electrophoresis, dynamic light scattering and conventional optical spectroscopy were combined to investigate the effectiveness of the surface modifications. Via the surface carboxyl residue, various antibodies were covalently conjugated to the fluorescent particles and the resultant fluorescent probes were used in detecting cancer cells through both direct fluorescent antibody and indirect fluorescent antibody assays, respectively.

Drug nanocarriers labeled with near-infrared-emitting quantum dots (quantoplexes): imaging fast dynamics of distribution in living animals.

The knowledge of the biodistribution of macromolecular drug formulations is a key to their successful development for specific tissue- and tumor-targeting after systemic application. Based on the polyplex formulations, we introduce novel drug nanocarriers, which we denote as "quantoplexes" incorporating near-infrared (IR)-emitting cadmium telluride (CdTe) quantum dots (QDs), polyethylenimine (PEI), and a macromolecular model drug [plasmid DNA (pDNA)], and demonstrate the ability of tracking these bioactive compounds in living animals. Intravenous application of bare QD into nude mice leads to rapid accumulation in the liver and peripheral regions resembling lymph nodes, followed by clearance via the liver within hours to days. Quantoplexes rapidly accumulate in the lung, liver, and spleen and the fluorescent signal is detectable for at least a week. Tracking quantoplexes immediately after intravenous injection shows rapid redistribution from the lung to the liver within 5 minutes, depending on the PEI topology and quantoplex formulation used. With polyethyleneglycol (PEG)-modified quantoplexes, blood circulation and passive tumor accumulation was measured in real time. The use of quantoplexes will strongly accelerate the development of tissue and tumor-targeted macromolecular drug carriers.

Molecular Design of Layer-by-Layer Functionalized Liposomes for Oral Drug Delivery.

Liposomes are small spherical vesicles composed mainly of phospholipids and cholesterol. Over the years, a number of liposomal formulations have shown clinical promise, but the use of liposomes in oral drug delivery is limited. This is partly due to the vulnerability of conventional liposomes to the detrimental effect of gastrointestinal destabilizing factors and also to the poor efficiency in intestinal absorption of liposomes. Some of these issues can be ameliorated using the layer-by-layer (LbL) assembly technology, which has been widely applied to modify the surface of various nanoparticulate systems. Discussions about LbL functionalization of liposomes as oral drug carriers, however, are scant in the literature. To fill this gap, this review presents an overview of the roles of LbL functionalization in the development of liposomes, followed by a discussion about major principles of molecular design and engineering of LbL-functionalized liposomes for oral drug delivery. Regarding the versatility offered by LbL assembly, it is anticipated that LbL-functionalized liposomes may emerge as one of the important carriers for oral drug administration in the future.

Development of Copper Nanoclusters for In Vitro and In Vivo Theranostic Applications.

Theranostics refers to the incorporation of therapeutic and diagnostic functions into one material system. An important class of nanomaterials exploited for theranostics is metal nanoclusters (NCs). In contrast to gold and silver NCs, copper is an essential trace element for humans. It can be more easily removed from the body. This, along with the low cost of copper that offers potential large-scale nanotechnology applications, means that copper NCs have attracted great interest in recent years. The latest advances in the design, synthesis, surface engineering, and applications of copper NCs in disease diagnosis, monitoring, and treatment are reviewed. Strategies to control and enhance the emission of copper NCs are considered. With this synopsis of the up-to-date development of copper NCs as theranostic agents, it is hoped that insights and directions for translating current advances from the laboratory to the clinic can be further advanced and accelerated.

Biocompatible off-stoichiometric copper indium sulfide quantum dots with tunable near-infrared emission via aqueous based synthesis.

The present study reports an aqueous synthesis approach towards off-stoichiometric copper indium sulfide quantum dots with emissions in the near-infrared spectral range. The photoluminescence properties of the dots, and in particular the appearance of dual emission at high Cu deficiency, were studied with temperature-dependent steady-state and transient photoluminescence spectroscopy.

Infrared-emitting colloidal nanocrystals: synthesis, assembly, spectroscopy, and applications.

Semiconductor nanocrystals produced by means of colloidal chemistry in a solvent medium are an attractive class of nanometer-sized building blocks from which to create complex materials with unique properties for a variety of applications. Their optical and electronic properties can be tailored easily, both by their chemical composition and particle size. While colloidal nanocrystals emitting in the infrared region have seen a burst of attention during the last decade there is clearly a paucity of review articles covering their synthesis, assembly, spectroscopic characterization, and applications. This Review comprehensively addresses these topics for II-VI, III-V, and IV-VI nanocrystals, examples being HgTe and Cd(x)Hg(1-) (x)Te, InP and InAs, and PbS, PbSe, and PbTe, respectively. Among the applications discussed here are optical amplifier media for telecommunications systems, electroluminescence devices, and noninvasive optical imaging in biology.

Multifunctionalized polymer microcapsules: novel tools for biological and pharmacological applications.

We describe recent developments with multifunctional nanoengineered polymer capsules. In addition to their obvious use as a delivery system, multifunctional nanocontainers find wide application in enzymatic catalysis, controlled release, and directed drug delivery in medicine. The multifunctionality is provided by the following components: 1) Luminescent semiconductor nanocrystals (quantum dots) that facilitate imaging and identification of different capsules, 2) superparamagnetic nanoparticles that allow manipulation of the capsules in a magnetic field, 3) surface coatings, which target the capsules to desired cells, 4) metallic nanoparticles in the capsule wall that act as an absorbing antenna for electromagnetic fields and provide heat for controlled release, and 5) enzymes and pharmaceutical agents that allow specific reactions. The unique advantage of multifunctional microcapsules in comparison to other systems is that they can be simultaneously loaded/functionalized with the above components, allowing for the combination of their properties in a single object.

Hydrogel-Based Materials for Delivery of Herbal Medicines.

Herbal medicine, as an integral component of oriental medicine, has assimilated into the lives of Asian people for millennia. The therapeutic efficiency of herbal extracts and ingredients has, however, been limited by various factors, including the lack of targeting capacity and poor bioavailability. Hydrogels are hydrophilic polymer networks that can imbibe a substantial amount of fluids. They are biocompatible, and may enable sustained drug release. Hydrogels, therefore, have attracted widespread studies in pharmaceutical formulation. This article first reviews the latest progress in the development of hydrogel-based materials as carriers of herbal medicines, followed by a discussion of the relationships between hydrogel properties and carrier performance. Finally, the promising potential of using hydrogels to combine medicinal herbs with synthetic drugs in one single treatment will be highlighted as an avenue for future research.

Combined atomic force microscopy and optical microscopy measurements as a method to investigate particle uptake by cells.

We propose a combination of atomic force microscopy (AFM) and optical microscopy for the investigation of particle uptake by cells. Positively and negatively charged polymer microcapsules were chosen as model particles, because their interaction with cells had already been investigated in detail. AFM measurements allowed the recording of adhesion forces on a single-molecule level. Due to the micrometer size of the capsules, the number of ingested capsules could be counted by optical microscopy. The combination of both methods allowed combined measurement of the adhesion forces and the uptake rate for the same model particle. As a demonstration of this system, the correlation between the adhesion of positively or negatively charged polymer microcapsules onto cell surfaces and the uptake of these microcapsules by cells has been investigated for several cell lines. As is to be expected, we find a correlation between both processes, which is in agreement with adsorption-dependent uptake of the polymer microcapsules by cells.

Nanoengineered polymer capsules: tools for detection, controlled delivery, and site-specific manipulation.

We present the concept of multifunctional nanoengineered polymer capsules and outline their applications as new drug delivery systems or supramolecular toolboxes containing, for example, enzymes capable of converting nontoxic prodrugs into toxic drugs at a designated location. Such functionalized nanocontainers offer a wide range of applications including enzymatic catalysis, controlled release, and directed drug delivery in medicine due to their multifunctionality. The unique advantage of capsules in comparison to other systems is that they can be functionalized or loaded simultaneously with the above-mentioned components, thus permitting multifunctional processes in single cells.

Carbon dot hybrids with oligomeric silsesquioxane: solid-state luminophores with high photoluminescence quantum yield and applicability in white light emitting devices.

We present a simple approach towards highly efficient solid-state luminophores with strong deep blue emission and a record high photoluminescence quantum yield of 60% by embedding water-soluble N,S-co-doped carbon dots into a polyhedral oligomeric silsesquioxane (POSS) matrix.

Near-infrared-emitting semiconductor quantum dots for tumor imaging and targeting.

Visualizing tumors with the help of near-infrared-emitting probes allows not only in vivo imaging, but also online analysis during surgical resection. Near-infrared-emitting semiconductor quantum dots (QDs) are highly fluorescent nanocrystals that can be modified to meet the needs of tumor-selective probes by variations in size, composition and internal structure (core-only, type I and type II core-shell QDs). The passive accumulation of probes in tumors, as a result of leaky vasculature, can be achieved with systemically injected QDs designed to circulate in the bloodstream and avoid clearance via the kidneys or the reticuloendothelial system. With the help of chemical strategies, QDs are decorated with surface ligands, including antibodies or peptides that bind antigens on tumor cells or tumor endothelium, which further improves the specificity of accumulation within tumors. Encapsulation of QDs into macromolecular structures allows the in vivo tracking of gene and drug carriers in real time. Considerable research has been undertaken to avoid acute and chronic toxicities of QDs by reducing the dose or replacing toxic elements with more biocompatible materials. This review discusses the benefits and potential disadvantages of QDs, and highlights recent advances in the application of these probes for tumor imaging and targeting.

Magnetic targeting and cellular uptake of polymer microcapsules simultaneously functionalized with magnetic and luminescent nanocrystals.

By using a flow channel system for modeling the bloodstream in the circulatory system and by locally creating a magnetic field gradient caused by a permanent magnet, we demonstrate specific trapping of polymer capsules simultaneously functionalized with two types of nanoparticles--magnetic and luminescent nanocrystals. In the regions where the capsules were trapped by the magnetic field, drastically increased uptake of capsules by cells has been observed. The uptake of capsules by cells could be conveniently monitored with a fluorescence microscope by the luminescence of CdTe nanocrystals that had been embedded into the shells of the capsules. Our experiments envisage the feasibility of magnetic targeting of polymer capsules loaded by pharmaceutical agents to pathogenic parts of a tissue.

The role of metal nanoparticles in remote release of encapsulated materials.

Laser mediated remote release of encapsulated fluorescently labeled polymers from nanoengineered polyelectrolyte multilayer capsules containing gold sulfide core/gold shell nanoparticles in their walls is observed in real time on a single capsule level. We have developed a method for measuring the temperature increase and have quantitatively investigated the influence of absorption, size, and surface density of metal nanoparticles using an analytical model. Experimental measurements and numerical simulations agree with the model. The treatment presented in this work is of general nature, and it is applicable to any system where nanoparticles are used as absorbing centers. Potential biomedical applications are highlighted.