3374-05-8Relevant academic research and scientific papers
Structural and morphological aspects of (fluoro)quinolone delivery by layered double hydroxide nanoparticles
Salguero, Yadira,García, Mónica Cristina,Mosconi, Giuliana,Rojas, Ricardo
, p. 19144 - 19152 (2018)
Layered double hydroxides (LDHs) have been proposed as delivery systems (DSs) of (fluoro)quinolones (QLNs) to overcome their low bioavailability and to prevent the emergence of resistant bacteria. Both LDH-DS synthesis as nanoparticles (NPs) and QLN interactions with the metal ions that constitute the layers are essential to improve their physicochemical, biopharmaceutical and antimicrobial properties. Here, LDH-DSs containing the basic form of nalidixic acid (Nal), used as a probe, were obtained by coprecipitation at variable and constant pH (LDH-Nal-pHvar and LDH-Nal-pHcte, respectively). For both syntheses, LDH NPs containing Nal anions (LDH-Nal-NPs), with sizes between 30 and 40 nm, were obtained. A coordination compound (Mg(Nal)2·4H2O, Mg(Nal)2) was also concurrent for LDH-Nal-pHcte, which modulated the drug release profile and antimicrobial properties of the LDH-Nal-NPs. Thus, Nal release from LDH-Nal-pHvar was produced mainly by anion exchange. The best fits, obtained for the Higuchi model, showed rate constants dependent on the exchanging anions (kH = 0.88 and 1.53 for NaCl 0.9% and buffer phosphate 0.05 M, pH = 7.4, respectively). The nanometric size of LDH-Nal-pHvar as well as its faster release rate allowed a minimum inhibitory concentration decrease (MIC = 32 μg mL?1) compared to the pure drug (MIC = 128 μg mL?1). Instead, the presence of Mg(Nal)2 in LDH-Nal-pHcte led to a more sustained and media independent Nal release, but a lower MIC (64 μg mL?1) than LDH-Nal-pHvar.
Synthesis, thermal behavior, and spectroscopic study of the solid nalidixate of selected light trivalent lanthanides
Dobies Návia, Marcos Vinícius,Alves Gálico, Diogo,Junior Caires, Flávio,Marques Luiz, José,Spezia Nunes, Ronaldo
, p. 1717 - 1727 (2018)
Solid-state [Ln(nal)3]·nH2O compounds, where Ln represents light trivalent lanthanide (La to Sm, except Pm), nal is nalidixate (C12H11N2O3), and n is the number of water molecules, were synthesized. Characterization and investigation were made by means of complexometry, elemental analysis, powder X-ray diffraction, Fourier transform infrared, near infrared (NIR) and diffuse reflectance spectroscopies, simultaneous thermogravimetry and differential thermal analysis, and differential scanning calorimetry. The dehydration process occurs in a single step up to 453?K. The final temperature of dehydration decreases from Pr(III) to Sm(III), and the thermal stability of anhydrous compounds increases from La(III) to Sm(III) (except Ce), and these behaviors are related to the decrease in the ionic radius of the lanthanide ion. The thermal decomposition of the anhydrous compounds occurs in three, four, or five consecutive steps, with formation of the respective oxides CeO2, Pr6O11, and Ln2O3 (Ln?=?La, Nd, and Sm) as final residues. The results also provide information concerning the composition and thermal behavior of these compounds. Spectroscopic studies in the UV–Vis and NIR regions provide information about the characteristics 4f–4f transitions for the Pr(III), Nd(III), and Sm(III) compounds, as well as the NIR region characteristic overtone and combination bands of the compounds.
