Mobility and fate of ligand stabilized semiconductor nanoparticles in landfill leachates.

Semiconductor quantum dots (QDs) are nanocrystals used in diverse optoelectronics. At the end of their useful life they are likely to end up in landfills, where they could be mobilzed by infiltrating rain water. In this work, spectroscopic and light scattering techniques were employed to investigate the environmental fate of QDs exposed to leachates from Austrian landfill sites containing municipal solid and bulky wastes.

Fluorescent Magnetopolymersomes: A Theranostic Platform to Track Intracellular Delivery.

We present a potential theranostic delivery platform based on the amphiphilic diblock copolymer polybutadiene--poly (ethylene oxide) combining covalent fluorescent labeling and membrane incorporation of superparamagnetic iron oxide nanoparticles for multimodal imaging. A simple self-assembly and labeling approach to create the fluorescent and magnetic vesicles is described. Cell uptake of the densely PEGylated polymer vesicles could be altered by surface modifications that vary surface charge and accessibility of the membrane active species.

Traceability of fluorescent engineered nanomaterials and their fate in complex liquid waste matrices.

The number of products containing engineered nanomaterials (ENMs) has increased due to their high industrial relevance as well as their use in diverse consumer products. At the end of their life cycle ENMs might be released to the environment and therefore concerns arise regarding their environmental impact. In order to track their fate upon disposal, it is crucial to establish methods to trace ENMs in complex environmental samples and to differentiate them from naturally-occurring nanoparticles.

Evaluation of High-Yield Purification Methods on Monodisperse PEG-Grafted Iron Oxide Nanoparticles.

Fundamental research on nanoparticle (NP) interactions and development of next-generation biomedical NP applications relies on synthesis of monodisperse, functional, core-shell nanoparticles free of residual dispersants with truly homogeneous and controlled physical properties. Still, synthesis and purification of e.g.

Triggered Release from Thermoresponsive Polymersomes with Superparamagnetic Membranes.

Magnetic polymersomes were prepared by self-assembly of the amphiphilic block copolymer poly(isoprene---isopropylacrylamide) with monodisperse hydrophobic superparamagnetic iron oxide nanoparticles (SPION). The specifically designed thermoresponsive block copolymer allowed for efficient incorporation of the hydrophobic nanoparticles in the membrane core and encapsulation of the water soluble dye calcein in the lumen of the vesicles. Magnetic heating of the embedded SPIONs led to increased bilayer permeability through dehydration of the thermoresponsive PNIPAM block.

Controlled magnetosomes: Embedding of magnetic nanoparticles into membranes of monodisperse lipid vesicles.

Magnetic nanoparticle-containing capsules have been proposed for many uses, including triggered drug delivery and imaging. Combining superparamagnetic iron oxide nanoparticles (SPIONs) with existing liposome drug delivery technology is an enticing near-future prospect, but it requires efficient methods of synthesis and formulation compatible with pharmaceutical applications. We report a facile way of producing large, unilamellar, and homogeneously sized magnetoliposomes with high content of monodisperse, hydrophobic SPIONs integrated in the lipid membrane by use of a solvent inversion technique.

Complete Exchange of the Hydrophobic Dispersant Shell on Monodisperse Superparamagnetic Iron Oxide Nanoparticles.

High-temperature synthesized monodisperse superparamagnetic iron oxide nanoparticles are obtained with a strongly bound ligand shell of oleic acid and its decomposition products. Most applications require a stable presentation of a defined surface chemistry; therefore, the native shell has to be completely exchanged for dispersants with irreversible affinity to the nanoparticle surface. We evaluate by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) the limitations of commonly used approaches.

Vibronic and vibrational coherences in two-dimensional electronic spectra of supramolecular J-aggregates.

In J-aggregates of cyanine dyes, closely packed molecules form mesoscopic tubes with nanometer-diameter and micrometer-length. Their efficient energy transfer pathways make them suitable candidates for artificial light harvesting systems. This great potential calls for an in-depth spectroscopic analysis of the underlying energy deactivation network and coherence dynamics.

System-Dependent Signatures of Electronic and Vibrational Coherences in Electronic Two-Dimensional Spectra.

In this work, we examine vibrational coherence in a molecular monomer, where time evolution of a nuclear wavepacket gives rise to oscillating diagonal- and off-diagonal peaks in two-dimensional electronic spectra. We find that the peaks oscillate out-of-phase, resulting in a cancellation in the corresponding pump-probe spectra. Our results confirm the unique disposition of two-dimensional electronic spectroscopy (2D-ES) for the study of coherences.

Ultrafast photo-induced charge transfer unveiled by two-dimensional electronic spectroscopy.

The interaction of exciton and charge transfer (CT) states plays a central role in photo-induced CT processes in chemistry, biology, and physics. In this work, we use a combination of two-dimensional electronic spectroscopy (2D-ES), pump-probe measurements, and quantum chemistry to investigate the ultrafast CT dynamics in a lutetium bisphthalocyanine dimer in different oxidation states. It is found that in the anionic form, the combination of strong CT-exciton interaction and electronic asymmetry induced by a counter-ion enables CT between the two macrocycles of the complex on a 30 fs timescale.