Developing novel lanthanide metal-organic frameworks (Ln-MOFs) to rapidly and reliably differentiate both metal ions in solution and volatile organic compounds (VOCs) in vapor is highly challenging. Here, we describe versatile Eu 3+ /Tb 3+ -MOFs based on a flexible ligand. It is noteworthy that the film fabricated using bimetallic Eu 0.47 Tb 0.63 -MOF and polyvinyl alcohol could serve as an easy and convenient luminescent platform for distinguishing different metal ions and VOCs. The luminescent film exhibits notable fingerprint correlation between the metal ions/VOCs and the emission intensity ratio of Eu 3+ /Tb 3+ ions in Ln-MOFs. As a result, the bimetallic Ln-MOFs show fast recognition of Fe 3+ ion with a response time of <10 s, and can effectively probe styrene vapor within 4 min. Since the developed Ln-MOF film is stable and reliable, this work presents a promising strategy to explore luminescent platforms capable of effectively sensing different metal ions and VOCs.

Poly(ether sulfone) (PES) nanofibers were prepared by the gas-jet/electrospinning of its solutions in N,N-dimethylformamide (DMF). The gas used in this gasjet/electrospinning process was nitrogen. The morphology of the PES nanofibers was investigated with scanning electron microscopy. The process parameters studied in this work included the concentration of the polymer solution, the applied voltage, the tip-collector distance (TCD), the inner diameter of the needle, and the gas flow rate. It was found from experimental results that the average diameter of the electrospun PES fibers depended strongly on these process parameters. A decrease in the polymer concentration in the spinning solutions resulted in the formation of nanofibers with a smaller diameter. The use of an 18 wt % polymer solution yielded PES nanofibers with an average diameter of about 80 nm. However, a morphology of mixed bead fibers was formed when the concentration of PES in DMF was below 20 wt % during gas-jet/electrospinning. Uniform PES nanofibers with an average diameter of about 200 nm were prepared by this electrospinning with the following optimal process parameters: the concentration of PES in DMF was 25 wt %, the applied voltage was 28.8 kV, the gas flow was 10.0 L/min, the inner diameter of the needle was 0.24 mm, the TCD was 20 cm, and the flow rate was 6.0 mL/h.

No abstract

In order to understand the interaction between quercetin and collagen clearly, the UV-vis, FTIR-HATR, and fluorescence spectroscopy were used, and the data obtained by these experiments suggested that quercetin could bind to collagen. Results of FTIR-HATR and UV-vis absorption spectra suggested that the interaction of quercetin and collagen did not alter the conformation of collagen. The fluorescence spectra revealed that collagen could cause the quenching of quercetin fluorescence through a dynamic quenching procedure. The calculated quenching constant K(SV) and bimolecular quenching rate constant k(q) suggested that diffusion played a major role in quenching. In addition, the interaction of quercetin and collagen was evaluated by calculating (determining) the number of binding sites (n) and apparent binding constant K(A).

No abstract