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61.
Alan Petersen 《Journal of bioethical inquiry》2009,6(1):9-12
Nanotechnologies are expected to have a substantial impact on our lives in the future. However, the nanotechnology field is
characterised by many uncertainties and debates surrounding the characterisation of technologies, the nature of the applications,
the potential benefits and the likely risks. Given the rapid development of nanotechnologies, it is timely to consider what,
if any, novel ethical challenges are posed by developments and how best to address these given the attendant uncertainties.
The three articles which comprise this symposium consider the philosophical, regulatory and risk perception and communication
questions that arise from this arena. 相似文献
62.
《Saudi Journal of Biological Sciences》2017,24(6):1243-1248
This work was conducted to evaluate the ability of grape molding fungus; Penicillium citrinum to synthesize silver nanoparticles (Ag NPs). The potency of biosynthesized Ag NPs was checked against the aflatoxigenic Aspergillus flavus var. columnaris, isolated from sorghum grains. Biosynthesized Ag NPs were characterized and confirmed in different ways. X ray diffraction (XRD), Energy Dispersive Spectroscopy (EDS), Transmission Electron Microscopy (TEM) and optical absorption measurements confirmed the bio-synthesis of Ag NPs. The in vitro antifungal investigation showed that biosynthesized Ag NPs were capable of inhibiting the growth of aflatoxigenic A. flavus var. columnaris. Utilization of plant pathogenic fungi in the Ag NPs biosynthesis as well as the use of bio-Ag NPs to control fungal plant diseases instead of chemicals is promising. Further work is needed to confirm the efficacy of the bio-Ag NPs against different mycotoxigenic fungi and to determine the potent applicable doses. 相似文献
63.
There are numerous techniques such as photolithography, electron-beam lithography and soft-lithography that can be used to precisely pattern two dimensional (2D) structures. These technologies are mature, offer high precision and many of them can be implemented in a high-throughput manner. We leverage the advantages of planar lithography and combine them with self-folding methods1-20 wherein physical forces derived from surface tension or residual stress, are used to curve or fold planar structures into three dimensional (3D) structures. In doing so, we make it possible to mass produce precisely patterned static and reconfigurable particles that are challenging to synthesize.In this paper, we detail visualized experimental protocols to create patterned particles, notably, (a) permanently bonded, hollow, polyhedra that self-assemble and self-seal due to the minimization of surface energy of liquefied hinges21-23 and (b) grippers that self-fold due to residual stress powered hinges24,25. The specific protocol described can be used to create particles with overall sizes ranging from the micrometer to the centimeter length scales. Further, arbitrary patterns can be defined on the surfaces of the particles of importance in colloidal science, electronics, optics and medicine. More generally, the concept of self-assembling mechanically rigid particles with self-sealing hinges is applicable, with some process modifications, to the creation of particles at even smaller, 100 nm length scales22, 26 and with a range of materials including metals21, semiconductors9 and polymers27. With respect to residual stress powered actuation of reconfigurable grasping devices, our specific protocol utilizes chromium hinges of relevance to devices with sizes ranging from 100 μm to 2.5 mm. However, more generally, the concept of such tether-free residual stress powered actuation can be used with alternate high-stress materials such as heteroepitaxially deposited semiconductor films5,7 to possibly create even smaller nanoscale grasping devices. 相似文献
64.
Atomic force microscopy (AFM) was used as a meaningful tool to characterize the nanostructure of gelatin from catfish (Ictalurus punctatus) skin. The gelatins extracted with pretreatments including acid pretreatment, alkaline pretreatment, and alkaline followed
by acid pretreatment (optimized extraction conditions). The resulting gelatins were imaged using AFM and their nanostructure
was studied. The AFM images showed that gelatin extracted with acid pretreatment had a coacervate structure while with alkaline
pretreatment there were separate aggregates. Spherical aggregates and annular pores were observed in AFM images of gelatin
with the optimized extraction conditions. AFM imaging of gelatin with a relative high concentration (0.5%) was successfully
done and the results help researchers to understand gelatin structures at the nanoscale. 相似文献
65.
In the scientific field, nanotechnology has offered multipurpose and designated functional nanoparticles (NPs) for the development of applications in nano-medicine. This present review focuses on cutting edge of nanotechnology in biomedical applications as drug carries in cancer treatment. The nanotechnology overcomes several limitations of drug delivery systems used in distinct therapeutic approaches of cancer treatment. The serious effect of conventional chemotherapeutics by nonspecific targeting, the lack of solubility, and the inability of chemotherapeutics entry to cancer cells which, offers a great opportunity for nanotechnology to play significant roles in cancer biology. The selective delivery of nano-drugs to the targeted cancer cells by the programmed way and avoiding nonspecific interactions to the healthy cells. The present review focuses on the methods of improving the size, shape and characteristics of nanomaterials which can be exploited for cancer therapy. The successful designing of nanocarriers can be tailored for cancer treatment for upcoming future as nano-medicines. 相似文献
66.
《Saudi Journal of Biological Sciences》2021,28(12):7241-7247
Selenium (Se) is a multifunctional trace element required in specific amounts for the optimal growth of aquatic finfish species. For this reason, this study investigated the effect of Se nanoparticles on the growth behavior, antioxidative capacity, and liver wellbeing of Striped catfish (Pangasianodon hypophthalmus). Striped catfish fed varying Se nanoparticles levels (0. 0.5, 1, and 2 mg/kg) in triplicate units and kept for 60 days. Striped catfish delivered dietary Se nanoparticles had markedly increased growth performance, specific growth rate (SGR), consumed feed, and protein efficiency ratio but reduced feed conversion ratio (FCR). The whole body, liver, muscle, and gills have higher Se accumulation levels in fish that received Se nanoparticles than the control with the highest level in fish fed 2 mg/kg. The carcass composition showed higher protein content in fish fed 1 and 2 mg/kg (p = 0.001 and 0.001) and higher ash content (p = 0.001 and 0.002) in fish fed 2 mg/kg than the remaining groups. Superoxide dismutase was meaningfully activated in Striped catfish delivered 1 and 2 mg Se nanoparticles/kg compared with the control (p < 0.05). Also, catalase and glutathione peroxidase activities were higher, and malondialdehyde level was lower in Striped catfish fed Se nanoparticles at 0.5, 1, and 2 mg/kg than the control (p < 0.05). The villi exhibited a visible increase in both height and branching with an increased level of Se nanoparticles in addition to the increased number of goblet cells. The Se nanoparticles-treated fish revealed dose-dependent modifications fluctuated from diffuse fatty vacuolization in hepatocytes with eccentric pyknotic hepatocytes nuclei. In conclusion, Se nanoparticles are required for the optimum growth behavior, antioxidative capacity, and liver wellbeing of Striped catfish. Based on SGR and FCR data's regression analysis, Se nanoparticles are recommended at 1.02–1.11 mg/kg diet. 相似文献
67.
Radwa A Mehanna Marwa M Essawy Mona A Barkat Ashraf K Awaad Eman H Thabet Heba A Hamed Hagar Elkafrawy Nehal A Khalil Abeer Sallam Marwa A Kholief Samar S Ibrahim Ghada M Mourad 《World journal of stem cells》2022,14(1):1-40
Regenerative medicine is the field concerned with the repair and restoration of the integrity of damaged human tissues as well as whole organs.Since the inception of the field several decades ago,regenerative medicine therapies,namely stem cells,have received significant attention in preclinical studies and clinical trials.Apart from their known potential for differentiation into the various body cells,stem cells enhance the organ's intrinsic regenerative capacity by altering its environment,whether by exogenous injection or introducing their products that modulate endogenous stem cell function and fate for the sake of regeneration.Recently,research in cardiology has highlighted the evidence for the existence of cardiac stem and progenitor cells(CSCs/CPCs).The global burden of cardiovascular diseases’morbidity and mortality has demanded an in-depth understanding of the biology of CSCs/CPCs aiming at improving the outcome for an innovative therapeutic strategy.This review will discuss the nature of each of the CSCs/CPCs,their environment,their interplay with other cells,and their metabolism.In addition,important issues are tackled concerning the potency of CSCs/CPCs in relation to their secretome for mediating the ability to influence other cells.Moreover,the review will throw the light on the clinical trials and the preclinical studies using CSCs/CPCs and combined therapy for cardiac regeneration.Finally,the novel role of nanotechnology in cardiac regeneration will be explored. 相似文献
68.
69.
Dan E. McNamara Duilio Cascio Julien Jorda Cheene Bustos Tzu-Chi Wang Madeline E. Rasche Todd O. Yeates Thomas A. Bobik 《The Journal of biological chemistry》2014,289(13):8852-8864
Dihydromethanopterin reductase (Dmr) is a redox enzyme that plays a key role in generating tetrahydromethanopterin (H4MPT) for use in one-carbon metabolism by archaea and some bacteria. DmrB is a bacterial enzyme understood to reduce dihydromethanopterin (H2MPT) to H4MPT using flavins as the source of reducing equivalents, but the mechanistic details have not been elucidated previously. Here we report the crystal structure of DmrB from Burkholderia xenovorans at a resolution of 1.9 Å. Unexpectedly, the biological unit is a 24-mer composed of eight homotrimers located at the corners of a cubic cage-like structure. Within a homotrimer, each monomer-monomer interface exhibits an active site with two adjacently bound flavin mononucleotide (FMN) ligands, one deeply buried and tightly bound and one more peripheral, for a total of 48 ligands in the biological unit. Computational docking suggested that the peripheral site could bind either the observed FMN (the electron donor for the overall reaction) or the pterin, H2MPT (the electron acceptor for the overall reaction), in configurations ideal for electron transfer to and from the tightly bound FMN. On this basis, we propose that DmrB uses a ping-pong mechanism to transfer reducing equivalents from FMN to the pterin substrate. Sequence comparisons suggested that the catalytic mechanism is conserved among the bacterial homologs of DmrB and partially conserved in archaeal homologs, where an alternate electron donor is likely used. In addition to the mechanistic revelations, the structure of DmrB could help guide the development of anti-obesity drugs based on modification of the ecology of the human gut. 相似文献
70.
《Bioorganic & medicinal chemistry letters》2014,24(7):1638-1649
The high versatility of graphene has attracted significant attention in many areas of scientific research from electronics to physics and mechanics. One of the most intriguing utilisation of graphene remains however in nanomedicine and synthetic biology. In particular, the last decade has witnessed an exponential growth in the generation of novel candidate therapeutics of multiple biological activities based on graphene constructs with small molecules, such as anti-cancer drugs. In this Digest, we summarise the different synthetic strategies and routes available to fabricate these promising graphene conjugates and the opportunities for the design of multi-functional tools for synthetic biology that they offer. 相似文献