Biocompatible Folic-Acid-Strengthened Ag-Ir Quantum Dot Nanozyme for Cell and Plant Root Imaging of Cysteine/Stress and Multichannel Monitoring of Hg2+ and Dopamine.

To boost the enzyme-like activity, biological compatibility, and antiaggregation effect of noble-metal-based nanozymes, folic-acid-strengthened Ag-Ir quantum dots (FA@Ag-Ir QDs) were developed. Not only did FA@Ag-Ir QDs exhibit excellent synergistic-enhancement peroxidase-like activity, high stability, and low toxicity, but they could also promote the lateral root propagation of Arabidopsis thaliana. Especially, ultratrace cysteine or Hg2+ could exclusively strengthen or deteriorate the inherent fluorescence property with an obvious "turn-on" or "turn-off" effect, and dopamine could alter the peroxidase-like activity with a clear hypochromic effect from blue to colorless. Under optimized conditions, FA@Ag-Ir QDs were successfully applied for the turn-on fluorescence imaging of cysteine or the stress response in cells and plant roots, the turn-off fluorescence monitoring of toxic Hg2+, or the visual detection of dopamine in aqueous, beverage, serum, or medical samples with low detection limits and satisfactory recoveries. The selective recognition mechanisms for FA@Ag-Ir QDs toward cysteine, Hg2+, and dopamine were illustrated. This work will offer insights into constructing some efficient nanozyme sensors for multichannel environmental analyses, especially for the prediagnosis of cysteine-related diseases or stress responses in organisms.

Poly-ß-cyclodextrin strengthen Pr6O11 porous oxidase mimic for dual-channel visual recognition of bioactive cysteine and Fe2.

To conveniently monitor bioactive cysteine (Cys) and Fe2+ in practice, a kind of poly-ß-cyclodextrin strengthen praseodymium oxide (Pr6O11) porous oxidase mimic (p-ß-CD@Pr6O11) was constructed by virtue of the strong coordination between nano Pr6O11 and poly-ß-cyclodextrin substrate. After its microstructure and physicochemical property were characterized in detail, it was noted that porous p-ß-CD@Pr6O11 exhibited excellent enzyme-like catalytic activity to accelerate the oxidation of 3,3',5,5,'-tetramethylbanzidine (TMB) and 2,2'-azinobis (3-ethylbenzo-thiazoline-6-sulfonic acid) ammonium salt (ABTS) with significant color-enhancement effect in the air. Based on the signal amplification, trace Cys could exclusively deteriorate the UV-vis absorbance at 653 nm of p-ß-CD@Pr6O11-TMB and Fe2+ alter the one at 729 nm of p-ß-CD@Pr6O11-ABTS with visual color changes. Under the optimized conditions, the proposed p-ß-CD@Pr6O11-TMB and p-ß-CD@Pr6O11-ABTS systems were successfully applied for dual-channel monitoring of Cys in Cys capsules and fetal bovine serum and Fe2+ in agricultural products with quite low detection limits, i.e., 7.8×10-9 mol·L-1 for Cys and 6.93×10-8 mol·L-1 (S/N=3) for Fe2+, respectively. The synergetic-enhancement detection mechanisms to Cys and Fe2+ were also proposed.

Spindle-shaped Cu-Ru mesoporous nanospheres with enhanced enzyme-like activity for visual differentiation of toxic o-/m-aminophenol and recognition mechanisms.

To effectively differentiate toxic aminophenol isomers, a kind of spindle-shaped Cu-Ru bimetal mesoporous nanozyme (Cu-Ru MPNZ) with high specific surface was developed by one-pot homogeneous reduction method, directed by hexadecyl trimethyl ammonium bromide (CTAB) in this work. By virtue of the distinctive microstructure, Cu-Ru MPNZ expressed superior bi-functional oxidase- and peroxidase-mimic activity to catalyze the oxidation of 3,3',5,5,'-tetramethylbenzidine (TMB) and 2,2'-azinobis (3-ethylbenzothiazoline-6- sulfonic acid) ammonium salt (ABTS) with low Michaelis-Menten constants and quick reaction rates. Especially, toxic aminophenol isomers could exclusively react with the oxydates of TMB or ABTS to express differentiable signals in color. Under the optimal conditions, Cu-Ru MPNZ was successfully applied for visual differentiation of toxic aminophenol isomers in real aqueous, juices and medicinal samples with low detection limits (1.60 × 10-8 mol/L for o-aminophenol and 3.25 × 10-8 mol/L for m-aminophenol) and satisfactory recoveries (96.6-103.5%). The different recognition mechanisms of Cu-Ru MPNZ to toxic o- and m-aminophenol isomers were proposed for the first time as far as we known. This work will provide a potential way to monitor different organic isomer pollution in future.

Ag nanozyme strengthened by folic acid: Superior peroxidase-mimicking activity and application for visual monitoring of dopamine.

Dopamine (DA) is an important neurotransmitter; however, any excess or deficiency of DA will cause several diseases in humans. To monitor DA efficiently and conveniently, a Ag nanozyme strengthened by bioactive folic acid (FA@AgNPs) was developed by homogeneous redox assembly. After the microstructure and performance were characterized in detail, it was noted that the proposed FA@AgNPs possessed superior peroxidase-like activity due to the ultra-small Ag nanoparticles and multiple amino, hydroxyl, and aromatic rings in FA. FA@AgNPs accelerated the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) with a low Michaelis constant (Km) and high maximal reaction rate (Vmax). Importantly, the characteristic absorbance intensity of FA@AgNPs-TMB-H2O2 at 652 nm (A652) was exclusively deteriorated in the presence of trace DA, accompanied by a visual color change from blue to colorless. Under the optimized conditions (pH 4.0, 300 µL 1.5 mM TMB, 300 µL 1.0 M H2O2 and incubated for 30 min at room temperature), there expressed an excellent linear relationship between lgA0/A652 and cDA from 1.0 ×10-8 to 6.67×10-6 mol/L with a low limit detection of 7.1×10-10 mol/L (S/N=3). When applied for monitoring of DA in real fruit juice and pharmaceutical samples, the recovery was between 96.6% and 104.9%, with RSD less than 2.2%. The enhanced peroxidase-like activity of the FA@AgNP system and its selective recognition mechanism for DA are also proposed.

2D Co3O4 modified by IrO2 nanozyme for convenient detection of aqueous Fe2+ and intercellular H2O2.

A portable sensor for visual monitoring of Fe2+ and H2O2, two-dimensional Co3O4 modified by nano-IrO2 (IrO2@2D Co3O4) was prepared in this work, for the first time, with the help of microwave radiation at 140 °C, which was further stabilized onto common test strips. The present IrO2@2D Co3O4 possessed superior dual-function enzyme-like activity with low toxicity and excellent biocompatibility. Especially, trace Fe2+ and H2O2 could exclusively alter their enzyme-like catalytic activity with discriminating hyperchromic or hypochromic effect, i.e., from blue to colorless or to dark blue for both IrO2@2D Co3O4 dispersion and its functionalized test strips. The linear regression equations were A652 = 0.5940 - 0.00041 cFe2+ (10-8 M, R2 = 0.9927) for Fe2+ and ∆A652 = 0.0023 cH2O2 + 0.00025 (10-7 M, R2 = 0.9982) for H2O2, respectively. When applied to visual monitoring of aqueous Fe2+ and intercellular H2O2, the recoveries were 101.2 ~ 102.5% and 95.8 ~ 103.7% with detection limits of 1.25 × 10-8 mol/L and 1.02 × 10-7 mol/L, respectively, far below the permitted values in drinking water set by the World Health Organization. The mechanisms for the enhancing enzyme-mimetic activity of IrO2@2D Co3O4 and its selective responses to Fe2+ and H2O2 were investigated in detail.

Convenient colorimetric-fluorescent dual-mode recognition of I- in agricultural products and visual determination of Hg2+ in drinking beverages using Ag-Pt bimetal quantum dot nanozyme.

Conveniently and efficiently monitoring I- and Hg2+ in agricultural products or drinking beverages for the protection of human health is currently a great challenge. With this aim, a Ag-Pt bimetal quantum-dot nanozyme boosted by bioactive folic acid (FA@Ag-Pt QDs) was first developed for multichannel monitoring of I- and Hg2+ in this work using a two-step liquid-phase reduction method. Not only did the present FA@Ag-Pt QDs possess superior peroxidase-like activity with Michaelis constant (Km) and maximal reaction rate (Vmax) of 0.01 mM/2.95 × 10-8 M·s-1 and 1.15 mM/3.88 × 10-8 M·s-1, respectively, trace Hg2+ or I- could exclusively alter their enzyme-mimic performance with obvious color changes from blue to colorless or dark blue. I- could also strengthen the inherent fluorescence property of FA@Ag-Pt QDs. When applied for visual monitoring of I- and Hg2+ in real beverages or iodine-containing agricultural products, the detection recoveries were 93.9 %-105.3 % and 96.8-104.3 % with low detection limits of 6.56 × 10-8 mol/L and 4.00 × 10-10 mol/L (S/N = 3), respectively. The recovery and detection limit for fluorescent detection of I- were 95.8 %-104.1 % and 1.75 × 10-8 mol/L (S/N = 3), respectively. The mechanisms driving the improved peroxidase-like activity of FA@Ag-Pt QDs and their selective monitoring of Hg2+ and I- were illustrated in detail. The proposed FA@Ag-Pt QDs will act as an efficient sensor for the practical multichannel monitoring of Hg2+ and I-, with superior catalytic signal amplification.

Cholesterol paradox in the community-living old adults: is higher better?

OBJECTIVE: To evaluate the associations of lipid indicators and mortality in Beijing Elderly Comprehensive Health Cohort Study. METHODS: A prospective cohort was conducted based on Beijing Elderly Comprehensive Health Cohort Study with 4499 community older adults. After the baseline survey, the last follow-up was March 31, 2021 with an average 8.13 years of follow-up. Cox proportional hazard model was used to estimate the hazard ratios (HR) with 95% CI for cardiovascular disease (CVD) death and all-cause death in associations with baseline lipid indicators. RESULTS: A total of 4499 participants were recruited, and the mean levels of uric acid, body mass index, systolic blood pressure, diastolic blood pressure, fasting plasma glucose, total cholesterol (TC), triglyceride, and low-density lipoprotein cholesterol (LDL-C) showed an upward trend with the increasing remnant cholesterol (RC) quarters (Ptrend < 0.05), while the downward trend was found in high-density lipoprotein cholesterol (HDL-C). During the total 36,596 person-years follow-up, the CVD mortality and all-cause mortality during an average 8.13 years of follow-up was 3.87% (95% CI: 3.30%-4.43%) and 14.83% (95% CI: 13.79%-15.86%) with 174 CVD death participants and 667 all-cause death participants. After adjusting for confounders, the higher level of TC (HR = 0.854, 95% CI: 0.730-0.997), LDL-C (HR = 0.817, 95% CI: 0.680-0.982) and HDL-C (HR = 0.443, 95% CI: 0.271-0.724) were associated with lower risk of CVD death, and the higher level of HDL-C (HR = 0.637, 95% CI: 0.501-0.810) were associated with lower risk of all-cause death. The higher level of RC (HR = 1.276, 95% CI: 1.010-1.613) increase the risk of CVD death. Compared with the normal lipid group, TC ≥ 6.20 mmol/L group and LDL-C ≥ 4.10 mmol/L group were no longer associated with lower risk of CVD death, while RC ≥ 0.80 mmol/L group was still associated with higher risk of CVD death. In normal lipid group, the higher levels of TC, LDL-C and HDL-C were related with lower CVD death. CONCLUSIONS: In community older adults, higher levels of TC and HDL-C were associated with lower CVD mortality in normal lipid reference range. Higher RC was associated with higher CVD mortality, which may be a better lipid indicator for estimating the CVD death risk in older adults.

[Effect of seed soaking with aluminum on seed germination and seedling physiology of Platycodon grandiflorum].

In order to study the effect of seed soaking with different aluminum solution on seed germination and seedling physiological characteristics of Platycondon grandiflorum, two P. grandiflorum varieties'seed (the white flower and the purple flower) were soaked in Al3+ solution with different concentrations (0, 10, 100, 250, 500, 750 and 1000 mg x L) for 24 h, then germinated in illumination incubator. Results showed that the aluminum toxicity on the trends of the germination rate, germination index and vigor index was positive associated with its concentration, and the Al tolerance of the purple was slightly greater than that of the white. There were some relationships between the physiological indices, which were the leakage rate of electrolyte, the malonaldehyde (MDA) content, the activities of peroxidase (POD) and superoxide dismutase (SOD) , the free praline(Pro) and the soluble sugar contents, with the concentrations of Al. It was suggested that there was Al tolerance difference between the two P. grandiflorum varieties: the purple flower was greater than the white.

Combined Single-Cell Profiling of lncRNAs and Functional Screening Reveals that H19 Is Pivotal for Embryonic Hematopoietic Stem Cell Development.

The generation of hematopoietic stem cells (HSCs) from embryonic endothelial precursors and pre-HSCs is precisely regulated by signaling pathways and transcription factors. Nevertheless, regulatory roles of non-coding RNAs remain unknown. Taking advantage of our ability to capture rare pre-HSCs and HSCs in vivo, we generated a single-cell landscape of long non-coding RNAs (lncRNAs) during HSC development. Combining bioinformatics and functional screening, we identified 6 lncRNAs influencing hematopoiesis in vitro. We further revealed that H19 lncRNA is pivotal for in vivo HSC emergence in aorta-gonads-mesonephros region. Early H19 lncRNA deficiency blocked endothelial-to-hematopoietic transition, which was independent of the H19-derived miR, miR-675. Moreover, H19-deficient pre-HSCs displayed promoter hypermethylation and concomitant downregulation of several master hematopoietic transcription factors, including Runx1 and Spi1. H19 deficiency increased the activity of S-adenosylhomocysteine hydrolase, a regulator of DNA methylation, which partially contributed to the observed hematopoietic defect. Our findings provide a resource for further analysis of lncRNAs in embryonic HSC development.