101 research outputs found
The impact of alkyl chain purity on lipid based nucleic acid delivery systems – is the utilization of lipid components with technical grade justified?
The physicochemical properties and transfection efficacies of two samples of a cationic lipid have been investigated and compared in 2D (monolayers at the air/liquid interface) and 3D (aqueous bulk dispersions) model systems using different techniques. The samples differ only in their chain composition due to the purity of the oleylamine (chain precursor). Lipid 8 (using the oleylamine of technical grade for cost-efficient synthesis) shows lateral phase separation in the Langmuir layers. However, the amount of attached DNA, determined by IRRAS, is for both samples the same. In 3D systems, lipid 8 p forms cubic phases, which disappear after addition of DNA. At physiological temperatures, both lipids (alone and in mixture with cholesterol) assemble to lamellar aggregates and exhibit comparable DNA delivery efficiency. This study demonstrates that non-lamellar structures are not compulsory for high transfection rates. The results legitimate the utilization of oleyl chains of technical grade in the synthesis of cationic transfection lipid
Relationship between structure and molecular interactions in monolayers of specially designed aminolipids
Artificial cationic lipids are already recognized as highly efficient gene therapy tools. Here, we focus on another potential use of aminolipids, in their electrically-uncharged state, for the formation of covalently cross-linked, one-molecule-thin films at interfaces. Such films are envisioned for future (bio-)materials applications. To this end, Langmuir monolayers of structurally different aminolipids are comprehensively characterized with the help of highly sensitive surface characterization techniques. Pressure-area isotherms, Brewster angle microscopy, grazing-incidence x-ray diffraction and infrared reflection–absorption spectrometry experiments provide a detailed, comparative molecular picture of the formed monolayers. This physico-chemical study highlights the relationship between chemical structures and intermolecular interactions, which can serve as a basis for the rational design of cross-linked thin films with precisely controlled properties
Lamellar versus micellar structures-aggregation behavior of a three-chain cationic lipid designed for nonviral polynucleotide transfer
Complete replication of hepatitis C virus in cell culture.
Many aspects of the hepatitis C virus (HCV) life cycle have not been reproduced in cell culture, which has slowed research progress on this important human pathogen. Here, we describe a full-length HCV genome that replicates and produces virus particles that are infectious in cell culture (HCVcc). Replication of HCVcc was robust, producing nearly 10(5) infectious units per milliliter within 48 hours. Virus particles were filterable and neutralized with a monoclonal antibody against the viral glycoprotein E2. Viral entry was dependent on cellular expression of a putative HCV receptor, CD81. HCVcc replication was inhibited by interferon-alpha and by several HCV-specific antiviral compounds, suggesting that this in vitro system will aid in the search for improved antivirals
The directional observation of highly dynamic membrane tubule formation induced by engulfed liposomes
Highly dynamic tubular structures in cells are responsible for exchanges between organelles. Compared with bacterial invasion, the most affordable and least toxic lipids were found in this study to be gentle and safe exogenous stimuli for the triggering of membrane tubules. A specific lipid system was internalized by NIH3T3 cells. Following cellular uptake, the constructed liposomes traveled towards the nucleus in aggregations and were gradually distributed into moving vesicles and tubules in the cytosol. The triggered tubules proceeded, retreated or fluctuated along the cytoskeleton and were highly dynamic, moving quickly (up to several microns per second), and breaking and fusing frequently. These elongated tubules could also fuse with one another, giving rise to polygonal membrane networks. These lipid systems, with the novel property of accelerating intracellular transport, provide a new paradigm for investigating cellular dynamics
A focus on critical aspects of uptake and transport of milk-derived extracellular vesicles across the Caco-2 intestinal barrier model
Bovine milk-derived extracellular vesicles (EVs) hold promises as oral drug delivery systems. Since EV
bioavailability studies are difficult to compare, key factors regarding EV uptake and intestinal
permeability remain little understood. This work aims to critically study uptake and transport
properties of milk-derived EVs across the intestinal barrier in vitro by standardization approaches.
Therefore, uptake properties were directly compared to liposomes in intestinal Caco-2 cells. Reliable
staining results were obtained by the choice of three distinct EV labeling sites, while non-specific dye
transfer and excess dye removal were carefully controlled. A novel fluorescence correction factor was
implemented to account for different labelling efficiencies. Both EV and liposome uptake occurred
mainly energy dependent with the neonatal Fc receptor (FcRn) providing an exclusive active pathway
for EVs. Confocal microscopy revealed higher internalization of EVs whereas liposomes rather
remained attached to the cell surface. Internalization could be improved when changing the liposomal
formulation to resemble the EV lipid composition. In a Caco-2/HT29-MTX co-culture liposomes and EVs
showed partial mucus penetration.
For transport studies across Caco-2 monolayers we further established a standardized protocol
considering the distinct requirements for EVs. Especially insert pore sizes were systematically
compared with 3 µm inserts found obligatory. Obtained apparent permeability coefficients (Papp)
reflecting the transport rate will allow for better comparison of future bioavailability testing
Experimental quantum speed-up in reinforcement learning agents
Increasing demand for algorithms that can learn quickly and efficiently has
led to a surge of development within the field of artificial intelligence (AI).
An important paradigm within AI is reinforcement learning (RL), where agents
interact with environments by exchanging signals via a communication channel.
Agents can learn by updating their behaviour based on obtained feedback. The
crucial question for practical applications is how fast agents can learn to
respond correctly. An essential figure of merit is therefore the learning time.
While various works have made use of quantum mechanics to speed up the agent's
decision-making process, a reduction in learning time has not been demonstrated
yet. Here we present a RL experiment where the learning of an agent is boosted
by utilizing a quantum communication channel with the environment. We further
show that the combination with classical communication enables the evaluation
of such an improvement, and additionally allows for optimal control of the
learning progress. This novel scenario is therefore demonstrated by considering
hybrid agents, that alternate between rounds of quantum and classical
communication. We implement this learning protocol on a compact and fully
tunable integrated nanophotonic processor. The device interfaces with
telecom-wavelength photons and features a fast active feedback mechanism,
allowing us to demonstrate the agent's systematic quantum advantage in a setup
that could be readily integrated within future large-scale quantum
communication networks.Comment: 10 pages, 4 figure
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