A sol-gel methodology has been duly developed in order to perform a controlled covalent coupling of tetrapyrrole macrocycles (e.g., porphyrins, phthalocyanines, naphthalocyanines, chlorophyll, etc.) ...to the pores of metal oxide networks. The resulting absorption and emission spectra intensities in the UV-VIS-NIR range have been found to depend on the polarity existing inside the pores of the network; in turn, this polarization can be tuned through the attachment of organic substituents to the tetrapyrrrole macrocycles before bonding them to the pore network. The paper shows clear evidence of the real possibility of maximizing fluorescence emissions from metal-free bases of substituted tetraphenylporphyrins, especially when these molecules are bonded to the walls of functionalized silica surfaces via the attachment of alkyl or aryl groups arising from the addition of organo-modified alkoxides.
Photoluminescence of gamma-irradiated Beryllium oxide Martínez-Baltezar, Rodrigo; Azorín-Nieto, Juan; Sosa-Fonseca, Rebeca
Applied radiation and isotopes,
October 2021, 2021-10-00, 20211001, Letnik:
176
Journal Article
Recenzirano
This study analyses the emission and excitation spectra of Beryllium Oxide (BeO) unirradiated and irradiated with 60Co gamma radiation because of its potential use in radiation dosimetry. ...Deconvolution of the spectra showed that using an excitation wavelength λexc = 330 nm, four emission bands centered at 404, 430, 468 and 545 nm are obtained; These emission bands appear in both irradiated and non-irradiated BeO; however, the irradiated samples exhibited an extra emission band centered at 416 nm. The excitation spectrum was obtained by setting the emission monochromator at a wavelength λ0 = 400 nm. By means of deconvolution, it was obtained that the emission spectrum of the non-irradiated samples is constituted by two bands centered at 307 and 331 nm, while for the irradiated samples the spectrum has three components centered at 297, 334 and 317 nm. In addition, it was found that the area under the curve of all emission bands decreases after irradiation, this may be due to the formation of electron-hole pairs after irradiation, which have the effect of reducing radiative phenomena, which it could be favorable for the applications of BeO in ionizing radiation dosimetry.
•Photoluminescence of unirradiated and gamma irradiated BeO was compared.•Deconvolution of PL spectra showed that for irradiated samples appears an extra peak in both emission and excitation spectra.•The PL intensity of BeO decreases with increasing radiation dose.
This work aimed at determining conditions that would allow us to control the size of the NPs and create a system with characteristics apt for biomedical applications. We describe a comprehensive ...study on the synthesis and physical characterization of two highly sensitive sets of triethylene glycol (TREG) and polyethylene glycol (PEG)-coated superparamagnetic iron oxide nanoparticles (SPIONs) to be evaluated for use as magnetic resonance (MR) contrast agents. The ferrofluids demonstrated excellent colloidal stability in deionized water at pH 7.0 as indicated by dynamic light scattering (DLS) data. The magnetic relaxivities,
r
2
, were measured on a 1.5 T clinical MRI instrument. Values in the range from 205 to 257 mM
−1
s
−1
were obtained, varying proportionally to the SPIONs’ sizes and coating nature. Further in vitro cell viability tests and in vivo biodistribution analyses of the intravenously administered nanoparticles showed that the prepared systems have good biocompatibility and migrate to several organs, mainly the meninges, spleen, and liver. Based on these results, our findings demonstrated the potential utility of these nanosystems as clinical contrast agents for MR imaging.
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