Search results for "Biophysic"
showing 10 items of 3565 documents
Switchable Bactericidal Effects from Novel Silica-Coated Silver Nanoparticles Mediated by Light Irradiation
2011
Here we report on the triggering of antibacterial activity by a new type of silver nanoparticle coated with porous silica, Ag@silica, irradiated at their surface plasmon resonant frequency. The nanoparticles are able to bind readily to the surface of bacterial cells, although this does not affect bacterial growth since the silica shell largely attenuates the intrinsic toxicity of silver. However, upon simultaneous exposure to light corresponding to the absorption band of the nanoparticles, bacterial death is enhanced selectively on the irradiated zone. Because of the low power density used for the treatments, we discard thermal effects as the cause of cell killing. Instead, we propose that …
Nuclear Magnetic Resonance for Cultural Heritage
2007
Abstract Nuclear magnetic resonance (NMR) portable devices are now being used for nondestructive in situ analysis of water content, pore space structure and protective treatment performance in porous media in the field of cultural heritage. It is a standard procedure to invert T 1 and T 2 relaxation data of fully water-saturated samples to get “pore size” distributions, but the use of T 2 requires great caution. It is well known that dephasing effects due to water molecule diffusion in a magnetic field gradient can affect transverse relaxation data, even if the smallest experimentally available half echo time τ is used in Carr–Purcell–Meiboom–Gill experiments. When a portable single-sided N…
Triple-target stimuli-responsive anti-COVID-19 face mask with physiological virus-inactivating agents
2021
Conventional face masks to prevent SARS-CoV-2 transmission are mostly based on a passive filtration principle. Ideally, anti-COVID-19 masks should protect the carrier not only by size exclusion of virus aerosol particles, but also be able to capture and destroy or inactivate the virus. Here we present the proof-of-concept of a filter mat for such a mask, which actively attracts aerosol droplets and kills the virus. The electrospun mats are made of polycaprolactone (PCL) a hydrophilic, functionalizable and biodegradable polyester, into which inorganic polyphosphate (polyP) a physiological biocompatible, biodegradable and antivirally active polymer (chain length, ∼40 Pi units) has been integr…
Biological tolerance of different materials in bulk and nanoparticulate form in a rat model: sarcoma development by nanoparticles
2006
In order to study the pathobiological impact of the nanometre-scale of materials, we evaluated the effects of five different materials as nanoparticulate biomaterials in comparison with bulk samples in contact with living tissues. Five groups out of 10 rats were implanted bilaterally for up to 12 months with materials of the same type, namely TiO 2 , SiO 2 , Ni, Co and polyvinyl chloride (PVC), subcutaneously with bulk material on one side of the vertebral column and intramuscularly with nanoparticulate material on the contralateral side. At the end of each implantation time, the site was macroscopically examined, followed by histological processing according to standard techniques. Malign…
Multifunctional Cationic PeptoStars as siRNA Carrier: Influence of Architecture and Histidine Modification on Knockdown Potential.
2019
RNA interference provides enormous potential for the treatment of several diseases, including cancer. Nevertheless, successful therapies based on siRNA require overcoming various challenges, such as poor pharmacokinetic characteristics of the small RNA molecule and inefficient cytosolic accumulation. In this respect, the development of functional siRNA carrier systems is a major task in biomedical research. To provide such a desired system, the synthesis of 3-arm and 6-arm PeptoStars is aimed for. The different branched polypept(o)idic architectures share a stealth-like polysarcosine corona for efficient shielding and a multifunctional polylysine core, which can be independently varied in s…
The crystal structure of bacteriophage Qβ at 3.5 å resolution
1996
Abstract Background: The capsid protein subunits of small RNA bacteriophages form a T=3 particle upon assembly and RNA encapsidation. Dimers of the capsid protein repress translation of the replicase gene product by binding to the ribosome binding site and this interaction is believed to initiate RNA encapsidation. We have determined the crystal structure of phage Qβ with the aim of clarifying which factors are the most important for particle assembly and RNA interaction in the small phages. Results The crystal structure of bacteriophage Qβ determined at 3.5 a resolution shows that the capsid is stabilized by disulfide bonds on each side of the flexible loops that are situated around the fi…
Dye selection for live cell imaging of intact siRNA
2011
Abstract Investigations into the fate of small interfering RNA (siRNA) after transfection may unravel new ways to improve RNA interference (RNAi) efficiency. Because intracellular degradation of RNA may prevent reliable observation of fluorescence-labeled siRNA, new tools for fluorescence microscopy are warranted to cover the considerable duration of the RNAi effect. Here, the characterization and application of new fluorescence resonance energy transfer (FRET) dye pairs for sensing the integrity of duplex siRNA is reported, which allows an assessment of the degradation status of an siRNA cell population by live cell imaging. A panel of high-yield fluorescent dyes has been investigated for …
Overcoming the barrier of CD8+ T cells: Two types of nano-sized carriers for siRNA transport
2019
Abstract Bioengineering immune cells via gene therapy offers treatment opportunities for currently fatal viral infections. Also cell therapeutics offer most recently a breakthrough technology to combat cancer. These primary human cells, however, are sensitive to toxic influences, which make the utilization of optimized physical transfection techniques necessary. The otherwise commonly applied delivery agents such as LipofectamineⓇ or strongly cationic polymer structures are not only unsuitable for in vivo experiments, but are also highly toxic to immune cells. This study aimed to improve the design of polymeric carrier systems for small interfering RNA, which would allow efficient internali…
Enhancing Gene Knockdown Efficiencies by Comparing siRNA-Loaded Cationic Nanogel Particles of Different Sizes
2015
lt;pgt;In order to silence the expression levels of pathogenic genes, small interfering RNA (siRNA) requires a nano-sized carrier for its safe and stable delivery into cells. In this research highlight, we focus on well-defined cationic nanohydrogel particles developed in our group for such purposes. To investigate the nanogels’ mechanism for enhanced knockdown efficiencies, we recently synthesized two sets of particles with similar material composition and siRNA-loading characteristics, but – according to the manufacturing process – of different sizes. Within this study, 100-nm-sized nanogel particles loaded with siRNA accumulated inside the lysosomes already after 4 h and could not induce…
SNAT2 silencing prevents the osmotic induction of transport system A and hinders cell recovery from hypertonic stress.
2005
AbstractUnder hypertonic conditions the induction of SLC38A2/SNAT2 leads to the stimulation of transport system A and to the increase in the cell content of amino acids. In hypertonically stressed human fibroblasts transfection with two siRNAs for SNAT2 suppressed the increase in SNAT2 mRNA and the stimulation of system A transport activity. Under the same condition, the expansion of the intracellular amino acid pool was significantly lowered and cell volume recovery markedly delayed. It is concluded that the up-regulation of SNAT2 is essential for the rapid restoration of cell volume after hypertonic stress.