Regulating the Porosity of Uranyl Phosphonate Frameworks with Quaternary Ammonium: Structure, Characterization, and Fluorescent Temperature Sensors.

Regulating the porosity of metal phosphonate frameworks is still challenging, even though this is not an issue for carboxylate-based metal-organic frameworks (MOFs). Quaternary ammonium cations are common template reagents widely used for structure control. However, it is not successful for uranyl phosphonate frameworks (UPFs) because the large volume sizes of templates make it challenging to enter the channels constructed by phosphonate ligands with small pore sizes and low dimensions. In this work, three new porous three-dimensional UPFs were synthesized using the phosphonate ligand and template reagents with the same geometry, namely, (TEA)2(UO2)3(TppmH4)2·2H2O (UPF-106), (TPA)2(UO2)3(TppmH4)2 (UPF-107), and (TBA)2(UO2)5(TppmH2)2(H2O)2·4H2O (UPF-108). The porosity of the UPFs in this work showed a positive relation with the sizes of the template ammonium cations. Thermogravimetric analysis and infrared and ultraviolet spectroscopy were performed. The variable-temperature fluorescence spectra of the three compounds showed that the fluorescence intensity has an excellent relation to temperature with a potential application as fluorescence temperature sensors.

A Multifunctional Porous Uranyl Phosphonate Framework for Cyclic Utilization: Salvages, Uranyl Leaking Prevention, and Fluorescent Sensing.

The material for managing and monitoring waste made from the waste itself is an excellent example of cyclic utilization, which could reduce issues and be more sustainable. A three-dimensional porous uranyl phosphonate MOF (UPF-105) was synthesized via a hydrothermal method. UPF-105 is stable in aqueous solution with pH in the range of 1-11 and maintains crystallinity below 215 °C. The uncoordinated phosphonate groups in the channels act as functional anchors to selectively capture uranyl ions, with a maximum uranium adsorption capacity of 170.23 mg g-1. The fluorescence of UPF-105 makes it a good candidate for a uranyl ion sensor in uranium-contaminated solutions with concentrations in the range of 5-90 ppm.

An ultra-stable hafnium phosphonate MOF platform for comparing the proton conductivity of various guest molecules/ions.

A porous hafnium-phosphonate MOF was synthesized using imidazole ionic liquids (ILs), namely PHOS-100(Hf), which has exceptional chemical stability in aqueous environments, even fuming acids. Its rigid framework with permanent porosity makes PHOS-100 an ideal candidate as a platform to fill with different functional guests such as acidic HCl, H2SO4, or H3PO4. The as-synthesized ILs@PHOS-100 exhibits significant humidity-dependent proton conductivities, increasing by four orders of magnitude from 45% RH to 95% RH at 25 °C. After post-treatment with strong acids, the acids@PHOS-100 show enhanced proton conduction at low relative humidities.

Pyrroloquinoline quinone-conferred neuroprotection in rotenone models of Parkinson's disease.

Pyrroloquinoline quinone (PQQ), a redox cofactor in the mitochondrial respiratory chain, has proven to protect neurons against glutamate-induced damage both in vitro and in vivo. This study was aimed to investigate the possible neuroprotective effects of PQQ in rotenone-induced Parkinson's disease (PD) model. Pre-treatment with PQQ prevented cultured SH-SY5Y cells from rotenone-induced apoptosis, accompanied by modulation of apoptosis-related proteins (Bcl-2, Bax and Smac), restoration of the mitochondrial membrane potential, inhibition of intracellular reactive oxygen species (ROS) production, suppression of tyrosine residues nitration, and dopamine redistribution. PQQ also exerted protective effects in an in vivo PD model, which was created by rotenone injection into the medial forebrain bundle of rats. Co-injection with PQQ and rotenone improved the apomorphine-evoked rotation, decreased neuronal loss, increased the ROS-scavenging ability, regulated intracellular expressions of mitochondrial complex subunits (Ndufs1-4), tyrosine hydroxylase, and vesicular monoamine transporter 2. Taken together, our results collectively suggest that PQQ confers neuroprotection in rotenone-induced PD model probably through complex and multifaceted mechanisms, at least involving oxidative stress, mitochondrial integrity, and dopamine functions.

Direct in Vivo Functionalizing Silkworm Fibroin via Molecular Recognition.

Recent works by Tansil et al. suggested a promising way to introduce functionalities into silk fibroin by simply feeding, which was expected to allow silk-based functional biomaterials to have scalable production and direct application. In this research, we aimed to obtain deeper understanding on such a smart strategy of selectively absorbing additives via molecular recognition and the impact of additives on the secondary structures of fibroin. We suggested that the partition ratio of the additive in fibroin and sericin was a critical parameter to evaluate the ability of the additive to enter fibroin, which showed a strong correlation with the isoelectric point (pI) of the additive. On the basis of the classical micelle model, we suggested that silk in vivo recognized additives with low pI and amphiphile chemical structure from other chemical similar additives and assembled them into fibroin. Fibroin-additive assemblies were rather stable that hindered the formation of ß-sheet and also crystallites, as indicated by FTIR and WAXD.