Charge injection engineering at organic/inorganic heterointerfaces for high-efficiency and fast-response perovskite light-emitting diodes.

The development of advanced perovskite emitters has considerably improved the performance of perovskite light-emitting diodes (LEDs). However, the further development of perovskite LEDs requires ideal device electrical properties, which strongly depend on its interfaces. In perovskite LEDs with conventional p-i-n structures, hole injection is generally less efficient than electron injection, causing charge imbalance. Furthermore, the popular hole injection structure of NiOx/poly(9-vinylcarbazole) suffers from several issues, such as weak interfacial adhesion, high interfacial trap density and mismatched energy levels. In this work, we insert a self-assembled monolayer of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid between the NiOx and poly(9-vinylcarbazole) layers to overcome these challenges at the organic/inorganic heterointerfaces by establishing a robust interface, passivating interfacial trap states and aligning the energy levels. We successfully demonstrate blue (emission at 493 nm) and green (emission at 515 nm) devices with external quantum efficiencies of 14.5% and 26.0%, respectively. More importantly, the self-assembled monolayer also gives rise to devices with much faster response speeds by reducing interfacial capacitance and resistance. Our results pave the way for developing more efficient and brighter perovskite LEDs with quick response, widening their potential application scope.

Comparative Metabolomics Combined with Physiological Analysis Revealed Cadmium Tolerance Mechanism in Indica Rice (Oryza sativa L.).

Cadmium (Cd) pollution reduces rice production and quality, putting food security and human health at risk. We conducted comparative physiology and metabolomic analyses in two indica rice ('NH199' and 'NH224') to elucidate the Cd-tolerance mechanism. Cd hampered rice growth, induced oxidative stress, and changed the metabolomics profiling of the root. The biochemical and physiological analysis demonstrated that NH224 exhibited a more potent Cd-tolerance ability than NH199. Cd was primarily distributed in root, and NH224 had a lower Cd translocation factor than NH199 by about 24%. The metabolomic analysis revealed 180 and 177 differentially accumulated metabolites between Cd-stressed seedlings and the controls in NH224 and NH199, respectively. In NH224, amino acids biosynthesis, hormone metabolism, lipids-related metabolism, phenylalanine metabolism, and phenylpropanoid biosynthesis pathways were more active and highly associated with antioxidant defense system, biosynthesis of the cell wall and phytochelatins, and maintenance of plasma membrane stability. These findings provide insights into the metabolic profiles of rice following Cd stress and the screening and breeding of Cd-tolerant rice varieties.

Spatially revealed perfluorooctane sulfonate-induced nephrotoxicity in mouse kidney using atmospheric pressure MALDI mass spectrometry imaging.

Perfluorooctane sulfonate (PFOS), an emerging environmental persistent pollutant, has attracted extensive attention due to its potential nephrotoxicity. However, little is known about the spatial variations of lipid metabolism associated with PFOS exposure. In this study, atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-MALDI MSI) was used to reveal the spatial distributions of PFOS and its adverse effect on lipid metabolism directly in mouse kidney sections. We have observed that PFOS accumulated in the renal pelvis and outer cortex regions, with some found in the medulla and inner cortex regions. Hematoxylin and eosin (H&E) staining results also demonstrated that the accumulation of PFOS caused damage to the mouse kidney, which was consistent with AP-MALDI MSI results. Furthermore, a total of 42 lipids were shown to be significantly different in the spatial distribution patterns and variations between control and PFOS exposure mice groups, including the significant down-regulation of lyso-glycerophospholipids (Lyso-GPs), phosphatidic acids (PA), phosphatidylcholines (PC), phosphatidylethanolamines (PE), phosphatidylserines (PS) sphingomyelins (SM) and sulfatides (ST) in renal medulla or cortex region of mouse kidney sections, and remarkable up-regulation of cholesterol and phosphatidylinositols (PI) in the cortex regions of mouse kidney sections. The AP-MALDI MSI provides a new tool to explore spatial distributions and variations of the endogenous metabolites for the risk assessment of environmental pollutants.

Metabolic study of aristolochic acid I-exposed mice liver by atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry imaging and machine learning.

Aristolochic acid I (AAI) as one of the major aristolochic acids (AAs) can cause progressive aristolochic acid nephropathy (AAN), which has been widely investigated since the early 1990s. Besides renal diseases, it has been recently revealed that AAI can induce liver damage. In this study, we report the molecular mapping of liver tissue sections from AAI-exposed mice using atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry (AP-MALDI MS) and show the distinct metabolic alterations when compared to the control group. We first used renal tissue sections to evaluate the performance of AP-MALDI MSI in spatial discrimination of different morphological regions. Then, the hepatic tissues from the AAI-induced and the control mice were analyzed, displaying rich metabolic profiles from both groups. Orthogonal partial least squares-discriminant analysis (OPLS-DA) is used to show complete separation of the two groups. A machine learning algorithm--least absolute shrinkage and selection operator (lasso) is used for statistical analysis of a total of 11,726 pixels of imaging data extracted from 3 normal liver and 3 AAI-exposed liver tissue sections, generating a classifier with high accuracy (99.81%). In total, 16 m/z values, including small metabolites and lipid species, are selected to discriminate AAI-exposed liver tissues. Finally, we explore the potentially impacted pathways using metabolomics pathway analysis (MetPA), indicating multiple metabolic pathway alterations including taurine and hypotaurine metabolism, glycerophospholipid metabolism, d-Glutamine and d-glutamate metabolism, and arachidonic acid metabolism, which provides new insights in AAI-induced hepatotoxicity.

Analysis of aristolochic acid I in mouse serum and tissues by using magnetic solid-phase extraction and UHPLC-MS/MS.

A method combining magnetic solid-phase extraction (MSPE) and ultra-high-pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for the analysis of aristolochic acids I (AAI) in mouse serum and tissues. The magnetic covalent organic frameworks (MNP@COF)-based MSPE exhibited high adsorption capacity towards AAI (93.1 mg/g) in optimal conditions. After MSPE extraction, AAI was separated with C18 column using gradient elution and quantified (m/z 342.21 â†’ 298.13) by UHPLC-MS/MS with monitor reaction monitoring (MRM) mode. This MSPE-based UHPLC-MS/MS method was validated with respected to lower limit of quantification (LLOQ), linearity, recovery, precision and accuracy of intra- and inter-day, and matrix effect. Good calibration linearities at the range of 1-500 ng/L for AAI in biological matrices (serum, kidney, and liver) with high correlation coefficient (R2) > 0.9970, and high enrichment factors (mean values from 1038 to 1045) were obtained. This method was highly sensitive to determine AAI with LLOQ within the range of 4.62-5.24 ng/L in extracted serum, kidney, and liver samples. Recoveries at 5, 50, 100 and 300 ng/L in biological samples ranged from 93.2 to 104.0%, and intra- and inter day accuracy and precision (defined as bias and coefficient of variation, respectively) were below ± 15%. The method was successfully applied in the analysis of biological samples collected from mice exposed with AAI with concentrations range of 0.007-0.041 µg/L for consecutive four days. The established method might be applied for the investigation of risk assessment and toxicity induced by long-time use of AAI-containing herbs or dietary supplements.

Integration of omics analysis and atmospheric pressure MALDI mass spectrometry imaging reveals the cadmium toxicity on female ICR mouse.

Acute cadmium toxicity induces multi-system organ failure. Mass spectrometry (MS)-based omics analyses and atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-MALDI MSI) are powerful tools for characterizing the biomarkers. Many studies on cadmium toxicity by metabolomics have been investigated, whereas the applications of lipidomics and MSI studies are still inadequate. In this study, the systematic metabolomics study on female ICR mice tissues including liver, kidney, heart, stomach, brain as well as spleen under cadmium exposure was firstly conducted and lipidomic characterizations on female ICR mice liver, kidney and heart were further constructed step by step. To deeply understand its toxicological mechanisms, several representative lipids on the mouse liver were visualized by AP-MALDI MSI. The results demonstrated that exposure to cadmium caused significant metabolic alterations in the liver, kidney and heart among all the tissues. Additionally, the toxicological mechanisms of cadmium in the mouse models are closely associated with the inflammation response, energy expenditure, oxidative stress, DNA and mitochondria damage, and lipid homeostasis. These insights could enhance knowledge in acute cadmium toxicity of public health and guide risk assessment in the future.