Synthesis, cytotoxicity, and biomacromolecule binding: Three isomers of nitrosylruthenium complexes with bidentate bioactive molecules as co-ligands.

Three isomeric nitrosylruthenium complexes [RuNO(Qn)(PZA)Cl] (P1, P2, and P3) with bioactive small molecules 8-hydroxyquinoline (Qn) and pyrazinamide (PZA) as co-ligands were synthesized, and their crystal structures were determined using X-ray diffraction technique. The cellular toxicity of the isomeric complexes was compared to understand the effects of the geometries on the biological activity of the complexes. Both the complexes and the human serum albumin (HSA) complex adducts affected the extent of proliferation of HeLa cells (IC50: 0.77-1.45 µM). P2 showed prominent activity-induced cell apoptosis and arrested cell cycles at the G1 phase. The binding constants (Kb) of the complex with calf thymus DNA (CT-DNA) and HSA were quantitatively evaluated using fluorescence spectroscopy in the range of 0.17-1.56 × 104 M-1 and 0.88-3.21 × 105 M-1, respectively. The average binding site (n) number was close to 1. Moreover, the structure of HSA and the P2 complex adduct solved at the resolution of 2.48 Å revealed that one PZA-coordinated nitrosylruthenium complex bound at the subdomain I of HSA via a noncoordinative bond. HSA could serve as a potential nano-delivery system. This study provides a framework for the rational design of metal-based drugs.

Highly fluorescent carbon dots from coix seed for the determination of furazolidone and temperature.

In this work, blue emission fluorescent carbon dots (CDs) were fabricated by using the hydrothermal strategy from coix seed for the first time. We found that the prepared CDs possessed many excellent characteristics including excitation-dependent properties, good solubility and strong photostability. The optimal excitation and emission wavelength of CDs were 363 and 435 nm, respectively. Unbelievably, the fluorescence of CDs was selectively and effectively quenched with the addition of furazolidone (Fu). The quenching mechanisms might be assumed to the static quenching and inner filter effect (IFE). Based on this principle, a novel fluorescence probe was developed for the determination of Fu. At the same time, the proposed probe showed excellent sensitivity and selectivity towards Fu with a wide linear range from 0.5 to 100 µM, and the corresponding detection limit was 0.096 µM. Moreover, the CDs also could be applied for the sensing of temperature. The practical application of the CDs for Fu detection in real samples was also confirmed with the satisfactory recoveries changing from 96.6% to 108.5%, which provided huge possibility in the field of medical analysis.