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Recent developments and trends in the application of strontium and its isotopes in biological related fields

Publication . Coelho, Inês; Castanheira, Isabel; Bordado, João Moura; Donard, Olivier; Silva, José Armando L.

Strontium is a chemical element without biological functions in humans. In fact, only two biological roles are known, both as a biomineral constituent. However, strontium and calcium (a significant biometal) present chemical similarities; hence, the absorption of the former by living organisms is plausible. Based on the particular properties of isotopes of strontium several applications of this chemical element in biological sciences have been developed. These include its radioactive and non-radioactive isotopes in medical applications or resorting to its stable isotopes as analytical tools in isotope fingerprinting (87Sr/86Sr) to study dietary habits and migration patterns of ancient populations, food authentication and forensic sciences. This article, reviews papers published between 2012 and 2016, highlights the use of strontium isotope ratios for such biological related applications and compiles an analytical database, providing a valuable tool for future studies in the area.

2017-05Journal article

Open access

Magnetite nanoparticles functionalized with propolis against methicillin resistant strains of Staphylococcus aureus

Publication . El-Guendouz, Soukaina; Lyoussi, Badiaa; Lourenço, João P.; Rosa da Costa, Ana M.; Miguel, Maria G.; Barrocas Dias, Cristina; Manhita, Ana; Jordao, Luisa; Nogueira, Isabel; Faleiro, Maria L.

Magnetite nanoparticles (MNPs) have been evaluated for inhibiting microbial growth and biofilm for- mation. In this study the effect of the nanocomposite Moroccan propolis extract / MNPs acting against methicillin resistant strains of Staphylococcus aureus (MRSA) was evaluated. Chemical composition of propolis was established by pyrolysis coupled to gas chromatography and mass spectrometry method (pyrolysis GC/MS). MNPs were obtained through the co-precipitation method. The fabricated nanostruc- ture was characterized by X-ray Diffraction (DRX), Transmission Electron Microscopy (TEM), and Fourier Transform-Infrared Spectroscopy (FTIR). TEM of MNPs provided a particle average size of 15 nm, FTIR spectral analysis enabled a fast way of identification of MNPs, attesting the occurrence of the different combinations. The use of MNPs loaded with propolis and the antibiotic chloramphenicol at Minimum Inhibitory Concentration (MIC) value inhib- ited the bacterial growth of MSSA (methicillin susceptible strain of S. aureus ) and MRSA strains. After the treatment with MNPs-OA-P-CLo nanocomposite (MNPs with oleic acid, propolis and chloramphenicol), the disruption of the bacterial cell was observed by TEM. The combination of propolis and chlorampheni- col in free form at MIC value largely impaired both MSSA and MRSA strains as, after 2 h of treatment, no viable cells of MRSA 2 and MRSA 16 were recovered. Hence, the results elucidated a new antibac- terial nanocomposite synthesis, for possible applications as prospective nanoantibacterial agents or drug carriers.

2019-06Journal article

Restricted access