Search results for "fluorescent"
showing 10 items of 863 documents
Naphthalimide imidazolium-based supramolecular hydrogels as bioimaging and theranostic soft materials
2020
1,8-Naphthalimide-based imidazolium salts differing for the alkyl chain length and the nature of the anion were synthesized and characterized to obtain fluorescent probes for bioimaging applications. First, their self-assembly behavior and gelling ability were investigated in water and water/dimethyl sulfoxide binary mixtures. Only salts having longer alkyl chains were able to give supramolecular hydrogels, whose properties were investigated by using a combined approach of fluorescence, resonance light scattering, and rheology measurements. Morphological information was obtained by scanning electron microscopy. In addition, conductive properties of organic salts in solution and gel state we…
Perylenetetracarboxylic anhydride as a precursor of fluorescent carbon nanoonion rings
2015
[EN] Thermal annealing at 400 degrees C of perylenetetracarboxylic anhydride in low molecular mass PEG gives rise to the formation of well defined nanoobjects of 2.5 nm height and size distribution from 10 to 65 nm (average 40 nm) after purification of the raw mixture with silicagel chromatography. TEM reveals that the flat nanoobjects are constituted of concentric graphenic rings (0.34 nm interlayer distance). The morphology of the nanoparticles resembles onion rings of nanometric dimensions (nanoonion rings C-NOR). C-NOR particles have an excitation dependent emission with lambda(em) from 430 to 570 nm and a maximum emission quantum yield of 0.49. C-NOR particles can be internalized into …
Cytotoxicity of Metal and Semiconductor Nanoparticles Indicated by Cellular Micromotility
2009
In the growing field of nanotechnology, there is an urgent need to sensitively determine the toxicity of nanoparticles since many technical and medical applications are based on controlled exposure to particles, that is, as contrast agents or for drug delivery. Before the in vivo implementation, in vitro cell experiments are required to achieve a detailed knowledge of toxicity and biodegradation as a function of the nanoparticles' physical and chemical properties. In this study, we show that the micromotility of animal cells as monitored by electrical cell-substrate impedance analysis (ECIS) is highly suitable to quantify in vitro cytotoxicity of semiconductor quantum dots and gold nanorods…
Expanding Two-Photon Intravital Microscopy to the Infrared by Means of Optical Parametric Oscillator
2010
Chronic inflammation in various organs, such as the brain, implies that different subpopulations of immune cells interact with the cells of the target organ. To monitor this cellular communication both morphologically and functionally, the ability to visualize more than two colors in deep tissue is indispensable. Here, we demonstrate the pronounced power of optical parametric oscillator (OPO)-based two-photon laser scanning microscopy for dynamic intravital imaging in hardly accessible organs of the central nervous and of the immune system, with particular relevance for long-term investigations of pathological mechanisms (e.g., chronic neuroinflammation) necessitating the use of fluorescent…
HPMA-based block copolymers promote differential drug delivery kinetics for hydrophobic and amphiphilic molecules.
2015
Abstract We describe a method how polymeric nanoparticles stabilized with (2-hydroxypropyl)methacrylamide (HPMA)-based block copolymers are used as drug delivery systems for a fast release of hydrophobic and a controlled release of an amphiphilic molecule. The versatile method of the miniemulsion solvent-evaporation technique was used to prepare polystyrene (PS) as well as poly-d/l-lactide (PDLLA) nanoparticles. Covalently bound or physically adsorbed fluorescent dyes labeled the particles’ core and their block copolymer corona. Confocal laser scanning microscopy (CLSM) in combination with flow cytometry measurements were applied to demonstrate the burst release of a fluorescent hydrophobic…
Novel biosensoric devices based on molecular protein hetero-multilayer films
1997
We have developed a novel concept for the modification of technical surfaces with molecularly well-organized layers of bioorganic components. A molecular construction set has been used to implement this concept which is based on molecularly stratified polyelectrolyte films as a structure decoupling protein layers from solid substrates. Utilizing this technology, one can start from a number of different substrates to obtain the same surface structures, on which protein hetero-multilayer films can be prepared to functionalize the interface for (potentially very different) purposes. We have demonstrated the viability of this concept by constructing a biosensor surface that was characterized by…
Endothelialization of chitosan porous conduits via immobilization of a recombinant fibronectin fragment (rhFNIII7–10)
2013
Abstract The present study aimed to develop a pre-endothelialized chitosan (CH) porous hollowed scaffold for application in spinal cord regenerative therapies. CH conduits with different degrees of acetylation (DA; 4% and 15%) were prepared, characterized (microstructure, porosity and water uptake) and functionalized with a recombinant fragment of human fibronectin (rhFNIII 7–10 ). Immobilized rhFNIII 7–10 was characterized in terms of amount ( 125 I-radiolabelling), exposure of cell-binding domains (immunofluorescence) and ability to mediate endothelial cell (EC) adhesion and cytoskeletal rearrangement. Functionalized conduits revealed a linear increase in immobilized rhFNIII 7–10 with rhF…
Biochips for cell biology by combined dip-pen nanolithography and DNA-directed protein immobilization.
2013
A general methodology for patterning of multiple protein ligands with lateral dimensions below those of single cells is described. It employs dip pen nanolithography (DPN) patterning of DNA oligonucleotides which are then used as capture strands for DNA-directed immobilization (DDI) of oligonucleotide-tagged proteins. This study reports the development and optimization of PEG-based liquid ink, used as carrier for the immobilization of alkylamino-labeled DNA oligomers on chemically activated glass surfaces. The resulting DNA arrays have typical spot sizes of 4-5 μm with a pitch of 12 μm micrometer. It is demonstrated that the arrays can be further functionalized with covalent DNA-streptavidi…
β-C3N4 Nanocrystals: Carbon Dots with Extraordinary Morphological, Structural, and Optical Homogeneity
2018
Carbon nanodots are known for their appealing optical properties, especially their intense fluorescence tunable in the visible range. However, they are often affected by considerable issues of optical and structural heterogeneity, which limit their optical performance and limit the practical possibility of applying these nanoparticles in several fields. Here we developed a synthesis method capable of producing a unique variety of carbon nanodots displaying an extremely high visible absorption strength (ε > 3 × 106 M(dot)−1 cm−1) and a high fluorescence quantum yield (73%). The high homogeneity of these dots reflects in many domains: morphological (narrow size distribution), structural (q…
Crossed 2D versus Slipped 1D π-Stacking in Polymorphs of Crystalline Organic Thin Films
2019
Polymorphs of organic semiconductors are of great interest as they shed light to structure-property relationships. The full X-ray thin film structure analysis of two polymorphs (B, G) of an important n-type semiconducting dicyano-distyrylbenzene based small molecule (CN-TFPA) is reported. Drastically different structures of the monotropic phases are revealed, that is an uncommon 2D crossed π-stacked arrangement for the B-phase versus a 1D slipped π-stack for G. Both phases exhibit a layered structure in the (100) plane with high structural integrity, driven by the hydrophobic contacts of the terminal CF3 groups; as (100) coincides with the film surface, this allows for exfoliation by scotch…