Hydrophobic and Luminescent Polydimethylsiloxane PDMS-Y2O3:Eu3+ Coating for Power Enhancement and UV Protection of Si Solar Cells.

Solar cells have been developed as a highly efficient source of alternative energy, collecting photons from sunlight and turning them into electricity. On the other hand, ultraviolet (UV) radiation has a substantial impact on solar cells by damaging their active layers and, as a result, lowering their efficiency. Potential solutions include the blocking of UV light (which can reduce the power output of solar cells) or converting UV photons into visible light using down-conversion optical materials. In this work, we propose a novel hydrophobic coating based on a polydimethylsiloxane (PDMS) layer with embedded red emitting Y2O3:Eu3+ (quantum yield = 78.3%) particles for UV radiation screening and conversion purposes. The favorable features of the PDMS-Y2O3:Eu3+ coating were examined using commercially available polycrystalline silicon solar cells, resulting in a notable increase in the power conversion efficiency (PCE) by ~9.23%. The chemical and UV stability of the developed coatings were assessed by exposing them to various chemical conditions and UV irradiation. It was found that the developed coating can endure tough environmental conditions, making it potentially useful as a UV-protective, water-repellent, and efficiency-enhancing coating for solar cells.

Terbium-doped carbon dots (Tb-CDs) as a novel contrast agent for efficient X-ray attenuation.

Metal-doped carbon dots have attracted considerable attention in nanomedicine over the last decade owing to their high biocompatibility and great potential for bioimaging, photothermal therapy, and photodynamic therapy. In this study, we prepared, and for the first time, examined terbium-doped CDs (Tb-CDs) as a novel contrast agent for computed tomography. A detailed physicochemical analysis revealed that the prepared Tb-CDs have small sizes (∼2-3 nm), contain relatively high terbium concentration (∼13.3 wt%), and exhibit excellent aqueous colloidal stability. Furthermore, preliminary cell viability and CT measurements suggested that Tb-CDs exhibit negligible cytotoxicity toward L-929 cells and demonstrate high X-ray absorption performance (∼48.2 ± 3.9 HU L g-1). Based on these findings, the prepared Tb-CDs could serve as a promising contrast agent for efficient X-ray attenuation.

Inhibitory mechanism of O-methylated quercetins, highly potent ß-secretase inhibitors isolated from Caragana balchaschensis (Kom.) Pojark.

ETHNOPHARMACOLOGICAL RELEVANCE: Caragana has a standing history of implementation in Traditional Chinese Medicine (TCM). Most species of this genus have been explored for multi-functional purposes, such as promoting blood circulation and curing neuralgia, fatigue, migraine, arthritis, and vascular hypertension (Meng et al., 2009). Among them, the well-known species C. sinica showed the most promising potential to increase the expression of ADAM10 among 313 tested medicinal plants, which is one of the promising approach for the treatment of Alzheimer's disease (AD). (Schuck et al., 2015). AIM OF THIS STUDY: The aim of this work is to explore ß-secretase inhibitory activity of compounds isolated from the aerial part of endemic Caragana balchaschensis (Kom.) Pojark. We provided a full characterization of their inhibitory mechanisms, binding affinities, and binding modes. MATERIALS AND METHODS: The isolation of quercetin derivatives was accomplished by various chromatographical approaches and their structures were annotated by spectroscopic analysis. The detailed kinetic behavior of ß-secretase inhibitors was determined by estimation of kinetic parameters (Km, Vmax, KI, and KIS). Binding affinities (KSV) and binding modes of inhibitors were elucidated by fluorescence quenching and molecular docking studies, respectively. RESULTS: O-methylated quercetins (2-7) were significantly effective in ß-secretase inhibition with IC50 ranging from 1.2 to 6.5 µM. The most active one (6) was 20-fold effective than the mother skeleton, quercetin. The O-methyl motif was a critical factor in ß-secretase inhibition: tri-O-methylated (1.2 µM) > di-O-methylated (3.5 µM) > mono-O-methylated (6.5 µM) > quercetin (25.2 µM). In the kinetic study, all quercetins (1-7) showed a noncompetitive inhibition, but glucoside ones (8 and 9) were mixed type I inhibitors. The binding affinities (KSV) were agreed with inhibitory potencies. The O-methylated quercetins were annotated as the most natural abundant metabolites in the aerial part by LC-ESI-TOF/MS. Binding modes of inhibitors to enzyme were elucidated by molecular docking experiments. CONCLUSION: This study disclosed that most of the major phenolic metabolites of the aerial part of C. balchaschensis are O-methylated quercetins, which have a significant inhibitory effect on ß-secretase, which is a critical factor for AD.

Effectiveness of cyclohexyl functionality in ugonins from Helminthostachys zeylanica to PTP1B and α-glucosidase inhibitions.

Ugonins are unique flavonoids with cyclohexyl motif from Helminthostachys zeylanica. Ugonins (1-6) from the target plant displayed significant inhibitions against both PTP1B (IC50s = 0.6-7.3 µM) and α-glucosidase (IC50s = 3.9-32.9 µM), which are crucial enzymes associated with diabetes. A cyclohexyl motif was proved to be the key functionality for PTP1B and α-glucosidase. For example, 1 was 26-fold effective to PTP1B and 15-fold to α-glucosidase than its mother compound, luteolin. This tendency was well elucidated with distinctive differences of binding affinities (KSV) between ugonins and mother compounds to PTP1B enzyme. Inhibitory mechanisms to PTP1B and α-glucosidase were fully characterized to be competitive, non-competitive and mixed type I according to the position of cyclohexyl functionality. In particular, the ugonin J (1) has a cyclohexyl on the B ring was estimated as a reversible, competitive and a slow binding inhibitor with parameters: Kiapp = 0.1234 µM, k3 = 0.5713 µM-1 min-1, and k4 = 0.0705 min-1. In-depth molecular docking experiments disclosed the specific binding sites and residues of competitive inhibitor (1) and non-competitive inhibitor (4) to PTP1B enzymes. As well, all six ugonins (1-6) also inhibited α-glucosidase effectively, in which cyclohexyl motif was also the key functionality of inhibitions.

Tyrosinase Inhibition and Kinetic Details of Puerol A Having But-2-Enolide Structure from Amorpha fruticosa.

Puerol A (1) from Amorpha fruticosa showed highly potent inhibition against both monophenolase (IC50 = 2.2 µM) and diphenolase (IC50 = 3.8 µM) of tyrosinase. We tried to obtain a full story of enzyme inhibitory behavior for inhibitor 1 because the butenolide skeleton has never been reported as a tyrosinase inhibitor. Puerol A was proved as a reversible, competitive, simple slow-binding inhibitor, according to the respective parameters; k3 = 0.0279 µM-1 min-1 and k4 = 0.003 min-1. A longer lag-phase and a reduced static-state activity of the enzyme explained that puerol A had a tight formation of the complex with Emet. Dose-dependent inhibition was also confirmed by high-performance liquid chromatography (HPLC) analysis using N-acetyl-l-tyrosine as a substrate, which was completely inhibited at 20 µM. A high binding affinity of 1 to tyrosinase was confirmed by fluorescence quenching analysis. Moreover, puerol A decreased melanin content in the B16 melanoma cell dose-dependently with an IC50 of 11.4 µM.