Search results for "bioengineering"
showing 10 items of 1963 documents
RCS1, a gene involved in controlling cell size inSaccharomyces cerevisiae
1991
Cloning and sequencing of RCS1, Saccharomyces cerevisiae gene whose product seems to be involved in timing the budding event of the cell cycle, is described. A haploid strain in which the 3'-terminal region of the chromosomal copy of the gene has been disrupted produces cells that are, on average, twice the size of cells of the parental strain. The critical size for budding in the mutant is similarly increased, and the disruption mutation is dominant in a diploid heterozygous for the RCS1 gene. Spores from this diploid have a reduced ability to germinate, the effect being more pronounced in the spores carrying the disrupted copy of RCS1. However, disrupted cells recover from alpha-factor tr…
Absolute Chiral Sensing in Dielectric Metasurfaces Using Signal Reversals.
2020
Sensing molecular chirality at the nanoscale has been a long-standing challenge due to the inherently weak nature of chiroptical signals, and nanophotonic approaches have proven fruitful in accessing these signals. However, in most cases, absolute chiral sensing of the total chiral refractive index has not been possible, while the strong inherent signals from the nanostructures themselves obscure the weak chiroptical signals. Here, we propose a dielectric metamaterial system that overcomes these limitations and allows for absolute measurements of the total chirality, and the possibility for a crucial signal reversal that enables chirality measurements without the need for sample removal. As…
Mechanical properties of carbon nanotube fibres: St Venant’s principle at the limit and the role of imperfections
2015
Abstract Carbon nanotube (CNT) fibres, especially if perfect in terms of their purity and alignment, are extremely anisotropic. With their high axial strength but ready slippage between the CNTs, there is utmost difficulty in transferring uniformly any applied force. Finite element analysis is used to predict the stress distribution in CNT fibres loaded by grips attached to their surface, along with the resulting tensile stress–strain curves. This study demonstrates that, in accordance with St Venant’s principle, very considerable length-to-diameter ratios (∼103) are required before the stress becomes uniform across the fibre, even at low strains. It is proposed that lack of perfect orienta…
Injectable Hydrogel for Synergetic Low Dose Radiotherapy, Chemodynamic Therapy and Photothermal Therapy
2021
Higher doses of radiotherapy (RT) are associated with resistance induction, therefore highly selective and controllable radiosensitizers are urgently needed. To address this issue, we developed a FeGA-based injectable hydrogel system (FH) that can be used in combination with low-dose radiation. Our FH can deliver FeGA directly to the tumor site via intratumoral injection, where it is a reservoir-based system to conserve FeGA. The photothermal properties of FeGA steadily dissolve FH under laser irradiation, and, simultaneously, FeGA reacts with a large amount of H2O2 in the cell to produce OH (Fenton reaction) which is highly toxic to mitochondria, rendering the cell inactive and reducing ra…
Smart materials meet multifunctional biomedical devices:Current and prospective implications for nanomedicine
2017
With the increasing advances in the fabrication and in monitoring approaches of nanotechnology devices, novel materials are being synthesized and tested for the interaction with biological environments. Among them, smart materials in particular provide versatile and dynamically tunable platforms for the investigation and manipulation of several biological activities with very low invasiveness in hardly accessible anatomical districts. In the following, we will briefly recall recent examples of nanotechnology-based materials that can be remotely activated and controlled through different sources of energy, such as electromagnetic fields or ultrasounds, for their relevance to both basic scien…
Effects of caspase inhibitors (z-VAD-fmk, z-VDVAD-fmk) on Nile Red fluorescence pattern in 7-ketocholesterol-treated cells: Investigation by flow cyt…
2007
Background: The 7-ketocholesterol (7KC)-induced cell death has some characteristics of apoptosis and is associated with polar lipid accumulation. So, we investigated the effects of the broad-spectrum caspase inhibitor z-VAD-fmk and of the caspase-2 inhibitor z-VDVAD-fmk on lipid profile evaluated by staining with Nile Red (NR). Methods: The 7KC-treated human monocytic U937 cells were cultured in the absence or in the presence of the caspase inhibitors z-VAD-fmk or z-VDVAD-fmk. When staining with NR is performed, neutral and polar lipids have yellow and orange/red emission, respectively, and fluorescence was then analyzed by flow cytometry (FCM) and by confocal laser scanning microscopy (CLS…
What Symbionts Teach us about Modularity
2013
The main goal of Synthetic Biology is to apply engineering principles to biotechnology in order to make life easier to engineer. These engineering principles include modularity: decoupling of complex systems into smaller, orthogonal subsystems that can be used in a range of different applications. The successful use of modules in engineering is expected to be reproduced in synthetic biological systems. But the difficulties experienced up to date with synthetic biology approaches question the short-term feasibility of designing life. Considering the “engineerable” nature of life, here we discuss the existence of modularity in natural living systems, particularly in symbiotic interactions, an…
Obsolescence and intervention: on synthetic-biological entities.
2014
Oftentimes, topics that might fall outside of science’s remit seem to end up becoming a part of it, sooner or later. This appears to be the case of synthetic biology, a new biological science (although some maintain that it is a form of engineering, or treat it as such; Endy, 2005), which seems to have become essential to the understanding of living beings and their extreme manipulation. I believe it to be a new form of biology. In truth, synthetic biology has a long history and, conceptually speaking, may well have formed part of the interests and research efforts of our illustrious predecessors throughout the first half of the twentieth century and even earlier. In any event, and broadly …
Activation of Human Osteoblasts via Different Bovine Bone Substitute Materials With and Without Injectable Platelet Rich Fibrin in vitro
2021
IntroductionThe aim of the in vitro study was to compare the effect of four bovine bone substitute materials (XBSM) with and without injectable platelet-reach fibrin for viability and metabolic activity of human osteoblasts (HOB) as well as expression of alkaline phosphatase (ALP), bone morphogenetic protein 2 (BMP-2), and osteonectin (OCN).Materials and MethodsCerabone® (CB), Bio-Oss® (BO), Creos Xenogain® (CX) and MinerOss® X (MO) ± i-PRF were incubated with HOB. At day 3, 7, and 10, cell viability and metabolic activity as well as expression of ALP, OCN, and BMP-2, was examined.ResultsFor non-i-PRF groups, the highest values concerning viability were seen for CB at all time points. Pre-t…
Sub-critical filtration conditions of commercial hollow-fibre membranes in a submerged anaerobic MBR (HF-SAnMBR) system: The effect of gas sparging i…
2012
A submerged anaerobic MBR demonstration plant with two commercial hollow-fibre ultrafiltration systems (PURON®, Koch Membrane Systems, PUR-PSH31) was operated using municipal wastewater at high levels of mixed liquor total solids (MLTS) (above 22gL -1). A modified flux-step method was applied to assess the critical flux (J C) at different gas sparging intensities. The results showed a linear dependency between J C and the specific gas demand per unit of membrane area (SGD m). J C ranged from 12 to 19LMH at SGD m values of between 0.17 and 0.5Nm 3h -1m -2, which are quite low in comparison to aerobic MBR. Long-term trials showed that the membranes operated steadily at fluxes close to the est…