The development of rare-earth combined Fe-based magnetic nanocomposites for use in biological theranostics.

Iron (Fe)-based nanoparticles (NPs) represented by FeO exhibit attractive properties, such as high saturation magnetization, low magneto-crystalline anisotropy, and good biocompatibility, and are useful as magnetic resonance imaging (MRI) contrast agents. However, the existence of artifacts makes the single magnetic resonance imaging mode lack accuracy in tumor diagnosis. To overcome this limitation, a strategy where rare-earth elements are combined with Fe-based NPs is applied.

Upgrading the Toolbox: Two-Photon Absorption Induced Cleavage of Coumarin Dimers for Light-Based 4D Printing.

The use of light for shaping and changing matter is of high relevance in polymer and material science. Herein, a photopolymer method is presented, which comprises the combination of 3D photo-printing at 405 nm light and subsequent modification under two-photon absorption (TPA) conditions at 532 nm light, adding the fourth dimension. The TPA-triggered cycloreversion reaction of an intramolecular coumarin dimer (ICD) structure occurs within the absorbing material.

Laser-Induced Au Catalyst Generation for Tailored ZnO Nanostructure Growth.

ZnO nanostructures, semiconductors with attractive optical properties, are typically grown by thermal chemical vapor deposition for optimal growth control. Their growth is well investigated, but commonly results in the entire substrate being covered with identical ZnO nanostructures. At best a limited, binary growth control is achieved with masks or lithographic processes.

Laser-Driven One- and Two-Dimensional Subwavelength Periodic Patterning of Thin Films Made of a Metal-Organic MoS Precursor.

Laser-based surface processing is an established way for the maskless generation of surface structures and functionalities on a large variety of materials. Laser-driven periodic surface texturing and structuring of thin films is reported for metallic-, semiconductive-, and polymeric films. Here, we introduce subwavelength surface patterning of metal-organic thin films of [MoS(SCNBu)], a MoS precursor.

An intelligent tumor microenvironment responsive nanotheranostic agent for 1/2 dual-modal magnetic resonance imaging-guided and self-augmented photothermal therapy.

Photothermal therapy (PTT), as a promising antineoplastic therapeutic strategy, has been harnessed to restrain tumor growth through near-infrared (NIR) irradiation mediated thermal ablation. Nevertheless, its biological applications are hampered by thermal diffusion and up-regulated heat shock proteins (HSPs). Herein, a versatile nanotheranostic agent is developed integrating ZnFeO nanoparticles (NPs), polydopamine (PDA), and MnO NPs for 1/2 dual-modal magnetic resonance (MR) imaging-guided and self-augmented PTT.

Cycloreversion performance of coumarin and hetero-coumarin dimers under aerobic conditions: unexpected behavior triggered by UV-A light.

Photochemical [2+2]-cycloadditions of coumarin-like monomers are the textbook paradigms of photo-formation and photo-cleavage reactions. The electronic conjugation length of monomers and dimers is quite different which results in almost fully separated UV/Vis absorption bands in the UV-A and UV-C. This feature enables the selective light-controlled conversion between monomeric and dimeric forms by the choice of the appropriate wavelengths.

Oxidative formation of bis-N-methylquinolinone from anti-head-to-head N-methylquinolinone cyclodimer.

The light-driven formation and cleavage of cyclobutane structural motifs resulting from [2 + 2]-pericyclic reactions, as found in thymine and coumarin-type systems, is an important and intensively studied photochemical reaction. Various applications are reported utilizing these systems, among others, in cross-linked polymers, light-triggered drug release, or other technical applications. Herein coumarin is most frequently used as the photoactive group.

Fusion of purple membranes triggered by immobilization on carbon nanomembranes.

A freestanding ultrathin hybrid membrane was synthesized comprising two functional layers, that is, first, a carbon nanomembrane (CNM) produced by electron irradiation-induced cross-linking of a self-assembled monolayer (SAM) of 4'-nitro-1,1'-biphenyl-4-thiol (NBPT) and second, purple membrane (PM) containing genetically modified bacteriorhodopsin (BR) carrying a C-terminal His-tag. The NBPT-CNM was further modified to carry nitrilotriacetic acid (NTA) terminal groups for the interaction with the His-tagged PMs forming a quasi-monolayer of His-tagged PM on top of the CNM-NTA. The formation of the Ni-NTA/His-tag complex leads to the unidirectional orientation of PM on the CNM substrate.

Assembling Carbon Nanotube Architectures.

Well-defined multiwalled carbon nanotube structures are generated on stainless steel AISI 304 (EN AW 1.4301) by chemical vapor deposition. Pulsed laser-induced dewetting (PLiD) of the surface, by 532 nm nanosecond laser pulses, is utilized for the preparation of metal oxide nanoparticle fields with a defined particle number per area.

Effect of elasticity on the phagocytosis of micro/nanoparticles.

A broad range of investigation methods and frameworks are currently used to throughly study the elasticity of various types of micro/nanoparticles (MNPs) with different properties and to explore the effect of such properties on their interactions with biological species. Specifically, the elasticity of MNPs serves as a key influencing factor with respect to important aspects of phagocytosis, such as the clathrin-mediated phagocytosis, caveolae-mediated phagocytosis, macropinocytosis, and cell membrane fusion. Achieving a clear understanding of the relationships that exist between the elasticity of MNPs and their phagocytic processes is essential to improve their performance in drug delivery, which is related to aspects such as circulation lifetime in blood, accumulation time in tissues, and resistance to metabolism.

Synthesis of gold-silica core-shell nanoparticles by pulsed laser ablation in liquid and their physico-chemical properties towards photothermal cancer therapy.

Due to the increasing scientific and biomedical interest in various nanoparticles (NPs) with excellent properties and the onset of their commercial use, a convenient and adjustable physical method for improved efficiency needs to be used for enabling their tech-scale production. Recently, great progress has been made in the large-scale production of NPs with a simple structure by pulsed laser ablation in liquid (PLAL). In this work, we synthesized gold-silica core-shell NPs by improved PLAL and provided a guide on how to investigate their physico-chemical properties and association with biological effects towards cancer photothermal therapy (PTT).

The role of phosphopeptides in the mineralisation of silica.

We investigated the silicification activity of hyperphosphorylated peptides in combination with long-chain polyamines (LCPA). The bioinspired in vitro silicification experiments with peptides containing different amounts of phosphorylated serines showed structure-activity dependence by altering the amount and morphology of the silica precipitate. Our study provides an explanation for the considerable metabolic role of diatoms in the synthesis of hyperphosphorylated poly-cationic peptides such as natSil-1A.

Formation of Highly Ordered Platinum Nanowire Arrays on Silicon via Laser-Induced Self-Organization.

Laser-induced periodic surface structures (LIPSS) provide an elegant solution for the generation of highly ordered periodic patterns on the surface of solids. In this study, LIPSS are utilized for the formation of periodic platinum nanowire arrays. In a process based on laser-stimulated self-organization, platinum thin films, sputter-deposited onto silicon, are transformed into nanowire arrays with an average periodicity of 538 nm.

Applications of magnetic materials separation in biological nanomedicine.

As a result of their advantages for superparamagnetic properties, good biocompatibility, and high binding capacity, functionalized magnetic materials became widely popular over the past couple of decades, being applied on large scale in various processes of sample preparation for biomedicine. In this work, we perform an in-depth review on the current progress in the field of magnetic bead separation, discussing in detail the physical basis of this process, various synthesis methods and surface modification strategies. We place special focus of attention as well on the latest applications of magnetic polymer microspheres in cell separation, protein purification, immobilized enzyme, nucleic acid separation, and extraction of bioactive compounds with low molecular weight.

Reactive metal-organic interfaces studied with hard x-ray photoelectron spectroscopy: controlled formation of metalloporphyrin interphase layers during metal vapor deposition onto porphyrin films.

Interfaces between organic semiconductors and metallic layers are ubiquitous in organic (opto-) electronic devices and can significantly influence their functionality. Here, we studied in situ prepared metal-organic interfaces, which were obtained by vapor deposition of metals (Co, Fe) onto organic semiconductor films (2H-tetraphenylporphyrin), with hard x-ray photoelectron spectroscopy. In these systems, the interphase zones, which are formed by diffusion and reaction of the metal in the organic material, can be clearly distinguished spectroscopically from the unreacted organic bulk, since they comprise the corresponding metalloporphyrins, CoTPP and FeTPP.

Substituting Coumarins for Quinolinones: Altering the Cycloreversion Potential Energy Landscape.

The light-activated cleavage of cyclobutane-based systems via [2 + 2] cycloreversions, such as thymine and coumarin dimers, is an important but still poorly understood ultrafast photochemical reaction. Systems displaying reversible cycloreversion have found various uses in cross-linked polymers, enhancing gas adsorption affinities in inorganics, and light-activated medical therapies. We report the identification of a heterogeneous mode of cycloreversion for a rarely examined coumarin analogue system.

Investigations on the elasticity of functional gold nanoparticles using single-molecule force spectroscopy.

A wide range of investigation tools and frameworks aimed at the in depth understanding of the physico-chemical properties of different nanomaterials and at exploring their cellular interactions and effects have been reported in the past couple of decades. Among these, Single-Molecule Force Spectroscopy (SMFS) emerges as a very important tool for characterizing nanoparticles (NPs) and one of its very valuable applications consists in the quantitative analysis of the NPs' elasticity. In SMFS experiments that tackle this subject, a sharp tip present on the apex of a cantilever is indented into a single NP, and then the Young's modulus is determined as a measure of its elasticity, which is one of the fundamental mechanical parameters affecting the structural and functional cellular parameters.

Mechanically metastable structures generated by single pulse laser-induced periodic surface structures (LIPSS) in the photoresist SU8.

Laser-induced periodic surface structures (LIPSS) with a periodicity of 351 nm are generated in the negative photoresist SU8 by single nanosecond laser pulse impact. Friction scans indicate the periodic pattern to comprise alternating regions of crosslinked and non-crosslinked SU8. Intriguingly, even minor mechanical stimuli in the order of nanonewtons cause the unfolding or rather the deletion of the characteristic periodic pattern similarly to the release of a pre-loaded spring.

Colloidal Gold Nanoparticles Induce Changes in Cellular and Subcellular Morphology.

Exposure of cells to colloidal nanoparticles (NPs) can have concentration-dependent harmful effects. Mostly, such effects are monitored with biochemical assays or probes from molecular biology, i.e.

Real-time, label-free monitoring of cell viability based on cell adhesion measurements with an atomic force microscope.

Background: The adhesion of cells to an oscillating cantilever sensitively influences the oscillation amplitude at a given frequency. Even early stages of cytotoxicity cause a change in the viscosity of the cell membrane and morphology, both affecting their adhesion to the cantilever. We present a generally applicable method for real-time, label free monitoring and fast-screening technique to assess early stages of cytotoxicity recorded in terms of loss of cell adhesion.

Diverse Applications of Nanomedicine.

The design and use of materials in the nanoscale size range for addressing medical and health-related issues continues to receive increasing interest. Research in nanomedicine spans a multitude of areas, including drug delivery, vaccine development, antibacterial, diagnosis and imaging tools, wearable devices, implants, high-throughput screening platforms, etc. using biological, nonbiological, biomimetic, or hybrid materials.

Photocleavage of coumarin dimers studied by femtosecond UV transient absorption spectroscopy.

Coumarins are a class of UV absorbing compounds which exhibit fast, photoinduced cyclobutane ring formation and cleavage reactions. The photophysics behind such processes hold significant relevance for biomedical and photoresponsive materials research. In order to further understand the underlying dynamics of the cleavage reaction, and develop strategies for increasing the reaction efficiency, UV transient absorption spectroscopy was applied to three unsubstituted, isomeric coumarin dimers: anti-head-to-head (anti-hh), syn-head-to-head (syn-hh) and syn-head-to-tail (syn-ht).

Basic Physicochemical Properties of Polyethylene Glycol Coated Gold Nanoparticles that Determine Their Interaction with Cells.

A homologous nanoparticle library was synthesized in which gold nanoparticles were coated with polyethylene glycol, whereby the diameter of the gold cores, as well as the thickness of the shell of polyethylene glycol, was varied. Basic physicochemical parameters of this two-dimensional nanoparticle library, such as size, ζ-potential, hydrophilicity, elasticity, and catalytic activity ,were determined. Cell uptake of selected nanoparticles with equal size yet varying thickness of the polymer shell and their effect on basic structural and functional cell parameters was determined.

Directed assembly of gold nanowires on silicon via reorganization and simultaneous fusion of randomly distributed gold nanoparticles.

Laser-induced reorganization and simultaneous fusion of nanoparticles is introduced as a versatile concept for pattern formation on surfaces. The process takes advantage of a phenomenon called laser-induced periodic surface structures (LIPSS) which originates from periodically alternating photonic fringe patterns in the near-field of solids. Associated photonic fringe patterns are shown to reorganize randomly distributed gold nanoparticles on a silicon wafer into periodic gold nanostructures.

Site-selective biomineralization of native biological membranes.

Biomineralization of silica precursors, mediated by self-assembled proteins, is performed by many organisms. The silica cell walls of diatoms are perhaps the most stunning biomineral structures. Although the mechanisms of biomineralization are still not fully understood, template-assisted formation of silica nanostructures has gained much attention in the materials science community.