Surcos : (poemas biselados)

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 201

Amphioxus encodes the largest known family of green fluorescent proteins, which have diversified into distinct functional classes

<p>Abstract</p> <p>Background</p> <p>Green fluorescent protein (GFP) has been found in a wide range of Cnidaria, a basal group of metazoans in which it is associated with pigmentation, fluorescence, and light absorbance. A GFP has been recently discovered in the pigmentless chordate <it>Branchiostoma floridae </it>(amphioxus) that shows intense fluorescence mainly in the head region.</p> <p>Results</p> <p>The amphioxus genome encodes 16 closely-related GFP-like proteins, all of which appear to be under purifying selection. We divide them into 6 clades based on protein sequence identity and show that representatives of each clade have significant differences in fluorescence intensity, extinction coefficients, and absorption profiles. Furthermore, GFPs from two clades exhibit antioxidant capacity. We therefore propose that amphioxus GFPs have diversified their functions into fluorescence, redox, and perhaps just light absorption in relation to pigmentation and/or photoprotection.</p> <p>Conclusion</p> <p>The rapid radiation of amphioxus GFP into clades with distinct functions and spectral properties reveals functional plasticity of the GFP core. The high sequence similarities between different clades provide a model system to map sequence variation to functional changes, to better understand and engineer GFP.</p

Comparison of different methodologies for obtaining nickel nanoferrites

Nickel nanoferrites were obtained by means of four different synthetic wet-routes: co-precipitation (CP), sonochemistry (SC), sonoelectrochemistry (SE) and electrochemistry (E). The influence of the synthesis method on the structural and magnetic properties of nickel ferrite nanoparticles is studied. Although similar experimental conditions such as temperature, pH and time of synthesis were used, a strong dependence of composition and microstructure on the synthesis procedure is found, as electron microscopy, X-ray diffraction and Mössbauer spectroscopy studies reveal. Whereas by means of the CP and SC methods particles of a small size around 5–10 nm, respectively, and composed by different phases are obtained, the electrochemical routes (E and SE) allow obtaining monodisperse nanoparticles, with sizes ranging from 30 to 40 nm, and very close to stoichiometry. Magnetic characterization evidences a superparamagnetic behavior for samples obtained by CP and SC methods, whereas the electrochemical route leads to ferromagnetic ferrite nanoparticles

Femtosecond laser generation of bimetallic oxide nanoparticles with potential X-ray absorbing and magnetic functionalities for medical imaging applications

Bimetallic nanoparticles have gained vivid attention due to their unique and synergistic properties. They can be used in fields such as solar cells, optics, sensing, as well as medicine. The generation of bimetallic nanoparticles, containing oxide phases of both magnetic and X-ray attenuating metals for bioimaging applications has been challenging with traditional chemical synthesis methods. An alternative is the generation of nanoparticles from binary oxide ceramics by laser ablation in liquid. However, the applicability of this technique for production of hybrid nanoparticles consisting of magnetic and X-ray absorbing elements has not been demonstrated yet. In this work, novel ceramics composed of bimetallic oxide phases of iron-tantalum, iron-tungsten, and ironbismuth were produced by a reaction-sintering method. The bulk samples were characterized with scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffractometry. Nanoparticles were produced in aqueous and ethanol solutions by employing a femtosecond laser and characterized with transmission electron microscopy, selected area electron diffraction, and energy dispersive X-ray spectroscopy. The results demonstrated that the production of binary oxide bulk ceramics and their subsequent laser ablation in liquids leads to the successful generation of bimetallic oxide nanoparticles, without a core-shell morphology. In addition, it was found that the ablation threshold fluence of bulk samples as well as the crystallinity of the synthesized nanoparticles is governed by both the nature of the metallic oxide ceramics and the employed liquid. The results pave the way for a single step generation of well-defined bimetallic nanoparticles by laser ablation that could potentially exhibit X-ray and magnetic absorption properties suitable for multimodal imaging applications.This research has been partially funded by the Spanish Ministerio de Ciencia e Innovacion through the research project MAT2015-67354R (MINECO-FEDER). Funding through a Marie Sklodowska-Curie Individual Fellowships (MSCA-IF 2014, 656908-NIMBLIS-ESR) of the Horizon 2020 program, and the Project PI-0030-2017 of the Junta de Andalucia in the framework of the integrated territorial initiative 20142020 for research and innovation in biomedicine and health sciences in the province of Cadiz is also greatly appreciated. The authors acknowledge support for scanning electron microscopy by Dr. Stephan Puchegger and the faculty center for nanostructure research at the University of Vienna

Pursuit of optimal synthetic conditions for obtaining colloidal zero-valent iron nanoparticles by scanning pulsed laser ablation in liquids

Liquid-Assisted Pulsed Laser Ablation (LA-PLA) is a promising top-down method to directly synthesize colloidal dispersions of nanoparticles in a eco-friendly manner. However, the role of LA-PLA synthesis parameters is not yet fully agreed. This work seeks to optimize the production of nanoscale zero-valent iron (nZVI) particles suitable for biomedical or environmental applications using nanosecond LA-PLA on iron targets with different ablation media, laser and target scanning parameters. The use of alcohols as solvents produces iron-iron oxide core-shell nanoparticles with amorphous cores, except for a small crystalline fraction corresponding to the biggest core sizes. Decreasing carbon chain length and complexity leads to a thinning of the carbonaceous material coatings and an increase of the colloidal stability and the nanoparticle productivity. Moreover, a decrease of solvent density and surface tension allows obtaining reduced sizes and polydispersity values. Among, laser and scanning parameters, the pulse accumulation per spot displayed a clear effect in boosting size and productivity. As main outcome, aqueous dispersions with suitable colloidal properties are obtained, either by transferring to water of optimized nZVI particles produced in ethanol, or by direct formation of nZVI particles and in situ coating with hydrophilic molecules in aqueous solutions of these moleculesThis research has been funded by the Spanish Ministry of Economy and Competitiveness (MINECO) and FEDER [research projects MAT2015-67354R, MAT2014-53961-R, and MAT2017- 86826-R] and by the Aragón government (DGA) [grant for consolidated group PLATON E31_17R]. OBM thanks the financial support from the “Ramón y Cajal Program” [research project RYC2010-07332] of the Spanish Ministry of Economy and Competitiveness (MINECO) and the H2020 Action H2020-MSCA-IF-2014_ST [grant 656908-NIMBLIS] of the Executive Agency for Research Manages of EU Commissio

Solvothermal synthesis and characterization of ytterbium/iron mixed oxide nanoparticles with potential functionalities for applications as multiplatform contrast agent in medical image techniques

A solvothermal route to prepare Glutathione capped hybrid ytterbium/iron oxide nanoparticles with potential applications as multiplatform contrast agent in medical image techniques has been developed. The influence of ytterbium/iron molar ratio used as precursor, as well as the degree of the autoclave filling on the structural and morphological characteristics of the obtained nanoparticles has been extensively studied. Although all nanoparticles present similar composition, with YbFeO3 being the majority phase, size and morphology of the as synthetized nanoparticles are highly influenced by the critical temperature and by the over -saturation reached during the solvothermal process. We have demonstrated that glutathione properly functionalizes the hybrid nanoparticles, increasing their colloidal stability and decreasing their cytotoxicity. Additionally, they show good imaging in magnetic resonance and X-ray computerized tomography, thereby indicating promising potential as a dual contrast agent. This work presents, for the first time, glutathione functionalized ytterbium/iron oxide nanoparticles with potential applications in Biomedicine. © 2022 Elsevier Ltd and Techna Group S.r.l

A new ex vivo method to evaluate the performance of candidate MRI contrast agents: a proof-of-concept study

BACKGROUND: Magnetic resonance imaging (MRI) plays an important role in tumor detection/diagnosis. The use of exogenous contrast agents (CAs) helps to improve the discrimination between lesion and neighbouring tissue, but most of the currently available CAs are non-specific. Assessing the performance of new, selective CAs requires exhaustive assays and large amounts of material. Accordingly, in a preliminary screening of new CAs, it is important to choose candidate compounds with good potential for in vivo efficiency. This screening method should reproduce as close as possible the in vivo environment. In this sense, a fast and reliable method to select the best candidate CAs for in vivo studies would minimize time and investment cost, and would benefit the development of better CAs. RESULTS: The post-mortem ex vivo relative contrast enhancement (RCE) was evaluated as a method to screen different types of CAs, including paramagnetic and superparamagnetic agents. In detail, sugar/gadolinium-loaded gold nanoparticles (Gd-GNPs) and iron nanoparticles (SPIONs) were tested. Our results indicate that the post-mortem ex vivo RCE of evaluated CAs, did not correlate well with their respective in vitro relaxivities. The results obtained with different Gd-GNPs suggest that the linker length of the sugar conjugate could modulate the interactions with cellular receptors and therefore the relaxivity value. A paramagnetic CA (GNP (E_2)), which performed best among a series of Gd-GNPs, was evaluated both ex vivo and in vivo. The ex vivo RCE was slightly worst than gadoterate meglumine (201.9 ± 9.3% versus 237 ± 14%, respectively), while the in vivo RCE, measured at the time-to-maximum enhancement for both compounds, pointed to GNP E_2 being a better CA in vivo than gadoterate meglumine. This is suggested to be related to the nanoparticule characteristics of the evaluated GNP. CONCLUSION: We have developed a simple, cost-effective relatively high-throughput method for selecting CAs for in vivo experiments. This method requires approximately 800 times less quantity of material than the amount used for in vivo administrations

Ex situ and in situ functionalized Yb/Fe nanoparticles obtained by scanning pulsed laser ablation in liquids: A route to obtain biofunctionalized multiplatform contrast agents for MRI and CT imaging

Two distinct strategies were used to improve the colloidal properties of hybrid Yb/Fe oxide NPs previously prepared by the pulsed liquid laser ablation process for use as a contrast agent in medical imaging. First, an exhaustive optimization process of the laser ablation synthesis parameters was carried out to reduce the hydrodynamic diameters of the Yb/Fe NPs. The hydrodynamic size was successfully reduced to <200 nm, thereby decreasing the polydispertivity index. Second, ex situ and in situ functionalization processes using glutathione, cysteamine, or polyethylenimine as capping agents have been developed to increase their colloidal stability at physiological pH values. Transmission electron microscopy, dynamic light scattering, Z-potential measurements, and Fourier Transform Infrared spectroscopy were used to examine the structure, morphology, colloidal and surface properties of Yb/Fe NPs. Colloidal stability of the Yb/Fe NPs as well as the linkage mechanism of functionalization have been studied extensively. This last parameter provides a critical information for subsequently bioconjugations in biomedical applications. Additionally, the biocompatibility of the Yb/Fe NPs was evaluated by MTT (3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide) experiments. These results indicate more appropriate colloidal characteristics and higher biocompatibility for ex situ-functionalized Yb/Fe NPs, especially when the capping agent is glutathione. Additionally, these Yb/Fe NPs show good magnetic resonance imaging and X-ray computerized tomography imaging abilities, thereby indicating promising potential as dual contrast agents

Very Bright Green Fluorescent Proteins from the Pontellid Copepod Pontella mimocerami

Marguerite E. Hunt is with UT Austin; Michael P. Scherrer is with UT Austin; Frank D. Ferrari is with the National Museum of Natural History at the Smithsonian Institution; Mikhail V. Matz is with UT Austin.Background -- Fluorescent proteins (FP) homologous to the green fluorescent protein (GFP) from the jellyfish Aequorea victoria have revolutionized biomedical research due to their usefulness as genetically encoded fluorescent labels. Fluorescent proteins from copepods are particularly promising due to their high brightness and rapid fluorescence development. Results -- Here we report two novel FPs from Pontella mimocerami (Copepoda, Calanoida, Pontellidae), which were identified via fluorescence screening of a bacterial cDNA expression library prepared from the whole-body total RNA of the animal. The proteins are very similar in sequence and spectroscopic properties. They possess high molar extinction coefficients (79,000 M−1 cm−) and quantum yields (0.92), which make them more than two-fold brighter than the most common FP marker, EGFP. Both proteins form oligomers, which we were able to counteract to some extent by mutagenesis of the N-terminal region; however, this particular modification resulted in substantial drop in brightness. Conclusions -- The spectroscopic characteristics of the two P. mimocerami proteins place them among the brightest green FPs ever described. These proteins may therefore become valuable additions to the in vivo imaging toolkit.This work was supported by the Ocean Exploration program of the National Oceanic and Atmospheric Administration (“Operation Deep Scope 2007”), and the National Institutes of Health grant R01 GM078247 to M. V. M. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Biological Sciences, School o

Ex situ and in situ functionalized Yb/Fe nanoparticles obtained by scanning pulsed laser ablation in liquids: A route to obtain biofunctionalized multiplatform contrast agents for MRI and CT imaging

Two distinct strategies were used to improve the colloidal properties of hybrid Yb/Fe oxide NPs previously prepared by the pulsed liquid laser ablation process for use as a contrast agent in medical imaging. First, an exhaustive optimization process of the laser ablation synthesis parameters was carried out to reduce the hydrodynamic diameters of the Yb/Fe NPs. The hydrodynamic size was successfully reduced to <200 nm, thereby decreasing the polydispertivity index. Second, ex situ and in situ functionalization processes using glutathione, cysteamine, or polyethylenimine as capping agents have been developed to increase their colloidal stability at physiological pH values. Transmission electron microscopy, dynamic light scattering, Z-potential measurements, and Fourier Transform Infrared spectroscopy were used to examine the structure, morphology, colloidal and surface properties of Yb/Fe NPs. Colloidal stability of the Yb/Fe NPs as well as the linkage mechanism of functionalization have been studied extensively. This last parameter provides a critical information for subsequently bioconjugations in biomedical applications. Additionally, the biocompatibility of the Yb/Fe NPs was evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) experiments. These results indicate more appropriate colloidal characteristics and higher biocompatibility for ex situ-functionalized Yb/Fe NPs, especially when the capping agent is glutathione. Additionally, these Yb/Fe NPs show good magnetic resonance imaging and X-ray computerized tomography imaging abilities, thereby indicating promising potential as dual contrast agents.This research has been funded by the Spanish Ministry of Economy and Competitiveness (MINECO) and FEDER [research projects MAT2015-67354R], the H2020 Action H2020-MSCA-IF-2014_ST [grant 656908-NIMBLIS] of the Executive Agency for Research Manages of EU Commission, the Proyectos Integradores MdM-IMEYMAT 2020 call (research project ULST-NANO), and the projects PECART-0096-2020 (Consejería Salud y Familias. JA Spain) and P20_01293 (Consejería Economía, Conocimiento, Empresas y Universidad. JA Spain). In addition, we acknowledge the received technical assistance from the SC-ICYT of the University of Cádiz. We also acknowledge to the Networking Research Centre on Bioengineering, Biomaterials, and Nanomedicine (CIBERBBN) (which is financed by the Instituto de Salud Carlos III (ISCIII) with assistance from the European Regional Development Fund (ERDF)) and the ICTS “NANBIOSIS”, specifically the FVPR/U20 (http://www.nanbiosis.es/portfolio/u20-in-vivo-experimentalplatform/) for providing access to the micro-CT. M.L. was supported by a post-doctoral grant of the Consejo Nacional de Ciencia y Tecnología from Mexico (CONACYT, no 619639).Peer reviewe