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The main objective of the preparation of the Fe 3- x Ga x O 4 (0.14 ≤ x ≤ 1.35) system was to further the knowledge of the magnetic response of Ga 3+ -doped magnetite for application as MRI contrast agents. With this purpose, monodisperse nanoparticles between 7 and 10 nm with different amounts of gallium were prepared from an optimized protocol based on thermal decomposition of metallo-organic precursors. Thorough characterization of the sample was conducted in order to understand the influence of gallium doping on the structural, morphological and magnetic properties of the Fe 3- x Ga x O 4 system. X-ray diffraction and X-ray absorption near-edge structure measurements have proved the progressive incorporation of Ga in the spinel structure, with different occupations in both tetrahedral and octahedral sites. Magnetization measurements as a function of field temperature have shown a clear dependence of magnetic saturation on the gallium content, reaching an M s value of 110 Am 2 kg -1 at 5 K for x = 0.14 (significantly higher than bulk magnetite) and considerably decreasing for amounts above x = 0.57 of gallium. For this reason, nanoparticles with moderate Ga quantities were water-transferred by coating them with the amphiphilic polymer PMAO to further analyse their biomedical potential. Cytotoxicity assays have demonstrated that Fe 3- x Ga x O 4 @PMAO formulations with x ≤ 0.57, which are the ones with better magnetic response, are not toxic for cells. Finally, the effect of gallium doping on relaxivities has been analysed by measuring longitudinal (T 1 -1 ) and transverse (T 1 -1 ) proton relaxation rates at 1.4 T revealing that nanoparticles with x = 0.14 Ga 3+ content present remarkable T 2 contrast and the nanoparticles with x = 0.26 have great potential to act as dual T 1 -T 2 contrast agents.

The analysis of the permeation kinetics of new UV filter formulations is of great importance since the kinetic parameters are related to the effectiveness of the product over time. The dynamics of this process can be evaluated by means of the calculation of the permeation kinetic constants, which can be obtained from the respective permeation profiles. This paper is aimed at improving the analytical performance of permeation assays using an on-line automatic system with spectrometric detection avoiding the chromatographic procedure and the usually manual sampling steps required using the traditional Franz diffusion cell. Then, the kinetics of permeation of octyl p -methoxycinnamate loaded in different microemulsions through a synthetic membrane (polyamide) was analysed at real time by UV-Vis and fluorescence spectroscopies. The spectral data were obtained at regular intervals of time (5 min) during 60 min, and the concentration of the permeated UV-filter was at each time calculated using univariate linear calibration. The interference caused by the presence of basil essential oil (oily phase) in some microemulsion samples was overcome using synchronous fluorescence spectroscopy (Δ λ = 60 nm) and partial least squares. In all cases, the permeation profiles were obtained (first-order kinetics) and the respective permeation kinetic constants were calculated. The validation of the proposed method was assessed by gas chromatographic-mass spectroscopy and non-significant differences for the obtained permeation kinetic constants were found between methods ( p = 0.05). Additionally, a commercial sample was analysed with the proposed methods and the results were validated by high performance liquid chromatography technique., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We present results concerning the fabrication of a new magnetorheological fluid with FeCo magnetic nanoparticles (NPs) as magnetic fillers. These NPs have been fabricated by using the chemical reduction technique and show a pure crystalline phase with size ranging among 30-50 nm and high magnetization, 212 ± 2 A m 2 kg -1 . They agglomerate due to the strong magnetic dipolar interaction among them. These FeCo nanoparticles were used to synthesize a magnetorheological fluid by using oleic acid as surfactant, mineral oil as carrier liquid and Aerosil 300 as additive to control the viscosity of the fluid. The synthesized fluid showed a strong magnetorheological response with increasing shear stress values as the magnetic field intensity increases. Thus, we have measured a superior performance up to 616.7 kA m -1 , with a yield stress value of 2729 Pa, and good reversibility after demagnetization process. This value competes with the best ones reported in the most recent literature. We have compared the obtained results with our previous reported ones by using high magnetization Fe NPs fabricated by the electrical explosion of wire method (Fe-EEW).

Manganese/iron ferrite nanoparticles with different Mn 2+/3+ doping grades have been prepared by a thermal decomposition optimized approach so as to ascertain the doping effect on magnetic properties and, especially, on the magnetic hyperthermia response. The oxidation state and interstitial position of Mn in the spinel structure is found to be critical. The particle size effect has also been studied by growing one of the prepared samples (from 10 to 15 nm in diameter) by a seed mediated growth mechanism. After analyzing the main structural and chemical parameters such as the Mn/Fe rate, crystalline structure, particle diameter, shape and organic coating, some Mn doping induced changes have been observed, such as the insertion of Mn 2+ cations yielded more anisotropic shapes. Magnetic characterization, carried out by DC magnetometry (M(H), M(T)) and electron magnetic resonance (EMR) techniques, has shown interesting differences between samples with varying compositions. Lower Mn doping levels lead to larger saturation magnetization values, while an increase of the Mn content causes the decrease of the effective magnetic anisotropy constant at low T. The homogeneous magnetic response under applied magnetic fields, together with the great effect of nanoparticle size and shape in such a response, has been confirmed by the EMR analysis. Finally, a detailed magnetic hyperthermia analysis has demonstrated the large influence of NP size and shape on the magnetic hyperthermia response. The optimized Mn 0.13 Fe 2.87 O 4 _G sample with a diameter of 15 nm and slightly truncated octahedral shape is presented as an interesting candidate for future magnetic hyperthermia mediated biomedical treatments.

A new green method was developed for the quantification of paraquat (PQ) in water samples based on the fluorescence emission enhancement of the herbicide signal after adsorption on sodium montmorillonite clay (MMT). Radiant emission processes are favored by increasing the molecular rigidity of the PQ since it adopts a planar position between the nano-sheets of the MMT. The advantages of the use of this clay are nontoxic, low cost and found in abundance in natural reserves. The proposed method was successfully used in determining PQ in natural water samples with recoveries of 73% to 95%. The fluorescence emission showed a good linear relationship with PQ concentrations from 2.0 to 8.0 μmol L-1 with a detection limit of 0.37 μmol L-1. The method is simple, inexpensive and does not require the use of reagents or organic solvents; which makes it very promising to achieve the goals of green chemistry. The proposed methodology could be the beginning of the development of future green sensors.

Thiosemicarbazones and their metal derivatives have long been screened as antitumor agents, and their interactions with DNA have been analysed. Herein, we describe the synthesis and characterization of compounds containing [CuL] + entities (HL = pyridine-2-carbaldehyde thiosemicarbazone) and adenine, cytosine or 9-methylguanine, and some of their corresponding nucleotides. For the first time, crystal structures of adenine- and 9-methylguanine-containing thiosemicarbazone complexes are reported. To the best of our knowledge, the first study on the affinity thiosemicarbazone-RNA is also provided here. Experimental and computational studies have shown that [CuL(OH 2 )] + entities at low concentration intercalate into dsRNA poly(rA)·poly(rU) through strong hydrogen bonds involving uracil residues and π-π stacking interactions. In fact, noncovalent interactions are present both in the solid state and in solution. This behaviour diverges from that observed with DNA duplexes and creates an optimistic outlook in achieving selective binding to RNA for subsequent possible medical applications.

The crystal structures of [(ppy)Pd(mu-pz)](2) (ppy = 2-(2-pyridyl)phenyl, pz = pyrazol-1-yl) (1) and two different solvatomorphs of it, [(ppy)Pd(mu-pz)](2) x 1/2 CH(2)Cl(2) (2) and [(ppy)Pd(mu-pz)](2) x 1/2 CHCl(3) (3) have been elucidated by powder (1 and 2) and single crystal (3) X-ray diffraction. In all of them two molecules fit together following a very similar pattern forming a "dimer". All neutral dinuclear square-planar complexes having mu-pz or related bridges and planar aromatic ligands completing the coordination spheres found in the CSD show a similar arrangement to those observed in compounds 1-3, consisting of "interlocked dimers" following a herringbone-like pattern. A DFT study reveals the simultaneous action of pi,pi- and T-stacking interactions occurring as two sets of orthogonally oriented binding forces, as well as anagostic bonds overlapped with the latter.