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The advances of iron based magnetic nanoparticles are extensively increasing due to the number of sources related to the synthesis process, the control on the particle dispersion and the interactions of ferrofluids that can be provide with different surface modifications. The wide range of uses granted to them are based on the physical, chemical stability and interaction properties in the different yields of material science. In this work, ferromagnetic iron carbide@iron oxide core@shell nanoparticles were synthesized with hydrophobic nature. Water dispersity was controlled by modifying the surface with a synthesized molecule of oleic acid with ethylenediamine by bioconjugation reaction obtaining a conjugated amide-amine modified oleic acid coating 6 nm magnetic nanoparticles with the capacity of being water dispersable. The synthesized nanoparticles, with modified organic acid and surface modified nanoparticle were characterized by TEM, DLS, zeta potential, mass spectrometry, FTIR and NMR.

Two bis-urea type receptors were synthesized containing a polyether bridge and two 4-nitrophenyl groups as chromogenic units, R1 and R2. Molecular recognition studies of receptors towards different tetraalkylammonium and alkali metal salts were carried out in DMSO by UV-Vis and 1H-NMR spectroscopy. The receptors were found to have high affinity for diverse anions and ion-pairs, showing the highest affinities towards the tetramethylammonium and sodium salts. The cation binding ability of the receptors was evidenced by means 1H NMR, mass spectrometric ESI+ studies and the crystal structures of some precursors. Additionally, the molecular modelling at the DFT level of the tetramethylammonium acetate complexes illustrates the potential ion-pair binding ability of the receptors: the anion is recognized through strong hydrogen bonds from the NH─ groups from the two urea sites, while the cation is bound by a combination of cation─π, C-H···O and C-H···π interactions.

In this work, we report on the synthesis of two new mono-alkylated tetrandrine derivatives with acridine and anthracene units, MAcT and MAnT. The compounds were fully characterized by physicochemical techniques and single-crystal X-ray diffraction analysis. In addition, both derivatives were studied as nucleotide receptors and double-stranded DNA binders in aqueous phosphate buffer at pH = 7.2 using UV–vis and fluorescence spectroscopy. According to the molecular recognition studies, MAcT and MAnT exhibit high affinity (K ∼ 105 M−1) and selectivity for ds-DNA, presumably in an intercalation mode. Finally, the anti-proliferative effects of the tetrandrine derivatives on different cancer cell lines were explored, revealing promising activities. Particularly, the mono-anthracene tetrandrine derivative MAnT showed an IC50 of 2.74 μg/mL on the HeLa cervical cancer cell line, representing a value 3.3 times smaller than that obtained for unsubstituted tetrandrine. Examination of the cytotoxic effects on the HeLa cell line by inverted microscopy suggests that the cell death mechanism consists basically in apoptosis. The molecular modelling of three ds-DNA-MAcT complexes, suggested that the macrocycles may use an intercalation binding mode towards DNA. MAcT is predicted to bind into the major groove of the ds-DNA providing non-covalent interactions such as electrostatic, van der Waals and hydrophobic interactions that lead to selectivity. Overall experimental data supports the mode of action of MAnT and MAcT as cytotoxic compounds against cancer cell lines via a DNA interaction mechanism.

The handling of metallic nanoparticles often requires their dispersion into several polar and nonpolar solvents. Solid-phase stages or polymer-based ligands are commonly required to complete the transfer. The construction of a thiol ligand based in oleic acid, and its ability to efficiently assist in gold and silver nanoparticle aqueous–organic phase transfer is reported. After the transfer, the particles are completely dispersed in an organic solvent, preserving their diameter and morphology, as confirmed by ultraviolet–visible spectroscopy and scanning transmission electron micrographs.