Synthesis and Characterization of Fluorescent Silica Nanoparticles with Large Stokes Shifts for Multiplexed Assays and Imaging

Modern approaches to biological and biomedical analysis demand ever-increasing levels of sensitivity, selectivity, and throughput. This challenge has been addressed in the work described herein via the synthesis, characterization, and proofs of concept of a series of single and multidye copolymerized fluorescent silica nanoparticles with large Stokes shifts and near infrared fluorescence. The prepared fluorescent probes exhibit substantially enhanced fluorescence signals relative to their constituent dyes, good indicators of biocompatibility, and readily distinguishable fluorescence signals, promoting the simultaneous detection of multiple targets and reducing both the cost and time per assay. A novel NIR-fluorescent aminocyanine dye was designed for incorporation into silica nanoparticles, then synthesized and characterized as detailed in the second chapter. Spectroscopic characterization confirmed the intended dye structure and revealed a large Stokes shift, near infrared fluorescence, and a relatively high quantum yield, indicating the suitability of this compound for bioanalytical applications and incorporation into silica nanoparticles as either a standalone fluorophore or as a resonance energy transfer acceptor for other UV-visible dyes. In the third chapter, the incorporation of the novel dye and other commercial dyes into silica nanoparticles is discussed, along with characterization and proofs of concept for in vivo and in vitro applications of the resultant fluorescent labels. Nanoparticle synthetic approaches, dye concentrations, and surface coating densities were optimized for fluorescence intensities and biocompatibility. Nanoparticles containing single and multiple dye species were synthesized per the optimal parameters, producing a series of fluorescent tags with distinct fluorescence signatures and large Stokes shifts. Synthesized nanoparticles were characterized in terms of sizes, synthetic yields, quantum yields, limits of detection, stability, and synthetic reproducibility. The suitability of surface modified nanoparticles to in vitro and in vivo applications was demonstrated via biotin linkage to streptavidin microbeads and fluorescence microscopy imaging, hemocompatibility studies, and protein binding studies. Finally, in the fourth chapter, resonance energy transfer characteristics of multidye copolymerized nanoparticles were characterized. Energy transfer efficiencies between donor-acceptor pairs, numbers of dye molecules per nanoparticle, and average distances between dye molecules were calculated, then Förster radii for different donor-acceptor pairs were estimated using two approaches and compared

Spectroscopic Studies of Carbocyanine and 2,4,6- Trisubstituted Pyridine Dyes for Bioanalytical and pH Indicating Applications

In part A, the effect of varying short-chain alkyl substitution on the spectroscopic properties of cyanine dyes was examined. Molar absorptivities and quantum yields were determined for groups of pentamethine and heptamethine dyes for which the substitution of the indole nitrogen was varied. For both sets of dyes, increasing alkyl chain length did not significantly change quantum yield or molar absorptivity. These results may be useful in designing new cyanine dyes. In part B, the effect of structure on the suitability of 2,4,6-trisubstituted pyridines as color pH indicators was studied by determining spectral effects of protonation, molar absorptivities, pKa values, and the structural origin of the spectral behavior. Good color indicating properties result from aniline substitution at the 4 position of pyridine and electron donating substitution at the 2 and 6 positions of pyridine, which provide a strong red shift in the spectra and greater red shifted peak absorptivity, respectively

Debate e interacción doctrinal en las artes epistolares castellanas de mediados del XVI

Gaspar de Texeda’s Primero Libro de cartas mensageras en estilo cortesano (1547-1553) is usually taken as a “not too serious” manual, and thus, it has a low place in the history of epistolography. This assessment does not come from a rigorous study of the work, but from the consolidation of prejudices defended by secretaries professionally and personally hostile to the author and to his writing style. The invectives exchanged between Texeda, Torquemada and Yciar in their respective manuals, illustrate well the different styles each one defended, as well as the debate taking place around the vernacular episolography.El Primero Libro de cartas mensageras en estilo cortesano (1547-1553) de Gaspar de Texeda es habitualmente considerado un manual ‘poco serio’, por lo que se le reserva un exiguo lugar en la historia de la epistolografía. Esta valoración no procede de un estudio riguroso de la obra sino de la consolidación de prejuicios extemporáneos defendidos por secretarios contrarios estilísticamente al autor y hostiles a éste profesional y personalmente. Las invectivas y réplicas contenidas en los tratados de Texeda, de Toquemada y de Yciar ilustran magníficamente las distintas corrientes epistolográficas de la época, así como el virulento debate que en esos momentos se estaba dirimiendo en torno a la práctica epistolar vernácula

Evaluating Biophysical Attributes of Environmentally Degraded Landscapes in Northern Ethiopia using LANDSAT ETM data and GIS

Biophysical attributes of environmentally degraded landscapes in Adwa district, northern Ethiopia, were evaluated using LANDSAT ETM data and GIS. Satellite remote sensing (RS) has captured the spatial distribution and variability of Adwa land covers (75% classification accuracy, 73% Kappa statistic). GIS-based analysis of degraded land’s biophysical attributes has revealed associations between land-cover types, landform elements and major soils groups in the district. Agricultural farms were located closer to human settlements, while woodlands furthest away from settlements. Moreover, wooded croplands were found between arable and woodlands, indicating encroaching human activities through agricultural expansion. Forests and woodlands were dominant on high mountains, steep slopes and depressions, while degraded shrublands and scrublands were prominent on Leptosols and on dissected uplands and hills. On the other hand, agriculture was prominent on rolling hills and uplands, concave-shaped foot-slopes, and on the soils of the district characterized as Fluvisols and Vertisols. This study provides base-line information and add to land cover knowledge for this and similar regions. Additionally, it has identified associations among biophysical attributes in degraded Ethiopian highlands have important management implications for both under-developed and over-utilized areas.Keywords: Land cover, land degradation, soil erosion, land rehabilitation, deforestation, Ethiopian highland

A regularity criterion in multiplier spaces to Navier-Stokes equations via the gradient of one velocity component

In this paper, we study regularity of weak solutions to the incompressible Navier-Stokes equations in $\mathbb{R}^{3}\times (0,T)$. The main goal is to establish the regularity criterion via the gradient of one velocity component in multiplier spaces.Comment: 9 pages. arXiv admin note: text overlap with arXiv:2005.1401