Dual-emission CdTe quantum dot@ZIF-365 ratiometric fluorescent sensor and application for highly sensitive detection of l-histidine and Cu2

Xylenol orange-modified CdTe quantum dots as a fluorescent/colorimetric dual-modal probe for anthrax biomarker based on competitive coordination

Bacillus anthracis spores can make humans infected with vicious anthrax, so it is significant to detect their biomarker 2,6-pyridinedicarboxylic acid (DPA). The development of dual-modal methods for DPA detection that are more flexible in practical applications remains a challenge. Herein, colorimetric xylenol orange (XO) was modified on fluorescent CdTe quantum dots (QDs) for dual-modal detection of DPA through competitive coordination. After the binding of XO on CdTe QDs via coordination with Cd²⁺, CdTe QDs displayed quenched red fluorescence and the bound XO was presented as red color. The competitive coordination of DPA with Cd²⁺ made XO released from CdTe QDs, causing the enhanced red fluorescence of CdTe QDs and the yellow color of free XO. On this basis, DPA was rapidly (1 min) quantified through fluorescent and colorimetric modes within the ranges of 0.1-5 μM and 0.5-40 μM, respectively. The detection limits for DPA were calculated as low as 42 nM and 240 nM, respectively assigned to fluorescent and colorimetric modes. The level of urinary DPA was further measured. Satisfactory relative standard deviations (fluorescent mode: 0.1%-10.2%, colorimetric mode: 0.8%-1.8%) and spiked recoveries (fluorescent mode: 100.0%-115.0%, colorimetric mode: 86.0%-96.6%) were obtained.

Highly Boosting Circularly Polarized Luminescence of Chiral Metal-Imidazolate Frameworks

To develop a simple and general method for improving the circularly polarized luminescence (CPL) performances of materials is of great significance. In this work, two pairs of CPL-active homochiral metal-organic frameworks (MOFs) P/M-Et and P/M-Et(Cd) with eta topology are reported. In comparison to the reported isomorphic Zn-imidazolate MOFs P-Me and M-Me, both luminescence dissymmetry factor (g_lum ) and photoluminescence quantum yields (Φ_PL ) of P-Et and M-Et are largely improved by simply changing the methyl group to an ethyl group of ligands in P-Et and M-Et. Furthermore, the |g_lum | values are significantly amplified up to 0.015 from 0.0057 by introducing the non-luminescent halogenated aromatics, while an enhanced fluorescence efficiency is observed simultaneously (from 27.2% to 47.3%). The figure of merit value is about 40 times larger than that of P-Me and M-Me. Similarly, the CPL performances of P/M-Et(Cd) are improved by about five times after encapsulating fluorobenzene molecules. This work represents a new and simple method for developing CPL-active MOF materials.

Zeolitic imidazolate framework-8 encapsulating gold nanoclusters and carbon dots for ratiometric fluorescent detection of adenosine triphosphate and cellular imaging

A novel nanoprobe was prepared by encapsulating carbon dots (CDs) and gold nanoclusters (AuNCs) into zeolitic imidazolate framework-8 (ZIF-8) for sensitive detecting adenosine triphosphate (ATP). Under excitation at 360 nm, the obtained CDs/AuNCs@ZIF-8 nanoprobe exhibits dual-emissions at 469 nm and 660 nm, respectively, corresponding to the fluorescence emission of CDs and the aggregation-induced emission enhancement (AIEE) of AuNCs. The framework of ZIF-8 in this probe can be degraded by ATP due to the coordination competition of ATP and 2-Methylimidazole towards zinc ion (Zn²⁺), resulting in the release of CDs and AuNCs. The following dispersion of CDs would improve efficiencies of the fluorescence excitation and the consequent emission of CDs. On the contrary, the AIEE of AuNCs would be decreased spontaneously after the AuNCs originally restricted in ZIF-8 were allowed to escape. The intensity ratio of fluorescence at 469 nm to that at 660 nm (I₄₆₉/I₆₆₀) was conveniently employed as the response signal for representing the amount of ATP. This nanoprobe exhibits excellent sensitivity and selectivity toward ATP, with a limit of detection (LOD) of 0.061 μM. Besides, low cytotoxicity of this nanoprobe facilitates its application as a fluorescent indicator in fluorescence imaging of living cells. Encapsulating two types of fluorescent nanomaterials by a degradable ZIF-8 structure makes the ratiometric fluorescence response of the nanocomposite probe towards the target analyte that destroys the ZIF-8 structure possible, and simplifies the application of the probe.

Abnormal histidine metabolism promotes macrophage lipid accumulation under Ox-LDL condition

Distinct macrophage populations exert highly heterogeneity and perform various functions, among which, a crucial function of lipid metabolism is highlighted. However, the role of histidine metabolism disorder in macrophage lipid metabolism remains elusive. Addressed this question, we sorted and cultured the bone marrow-derived macrophages (BMDMs) of histidine decarboxylase (Hdc) knockout (Hdc-/-) mice with an in vitro oxidized low-density lipoprotein (ox-LDL) model, and detected the intracellular lipids by Oil Red O staining as well as lipid probe staining. Astemizole, a canonical and long-acting histamine H1 receptor (H1R) antagonist, was applied to elucidate the impact of antagonizing the H1R-dependent signaling pathway on macrophage lipid metabolism. Subsequently, the differential expressed genes were screened and analyzed in the bone marrow-derived CD11b+ immature myeloid cells of Hdc-/- and Hdc+/+ mice with a high fat diet by the microarray study. The expression levels of cholesterol metabolism-related genes were examined by qRT-PCR to explore underlying mechanisms. Lastly, we used a high-sensitivity histidine probe to detect the intracellular histidine in the BMDMs after oxidative stress. The results revealed that histidine metabolism disorder and histamine deficiency aggravated lipid accumulation in the ox-LDL-treated BMDMs. The expression level of H1R gene in the BMDMs was down-regulated after ox-LDL stimulation. The disruption of the H1R-dependent signaling pathway by astemizole further exacerbated ox-LDL-induced lipid deposition in the BMDMs partly by up-regulating scavenger receptor class A (SR-A) for lipid intake, down-regulating neutral cholesteryl ester hydrolase (nCEH) for cholesterol esterification and down-regulating ATP-binding cassette transporters A1 (ABCA1) and ABCG1 for reverse cholesterol transport. The intracellular histidine increased under ox-LDL condition, which was further increased by Hdc knockout. Collectively, these results partially reveal the relationship between histidine metabolism and lipid metabolism in the BMDMs and offer a novel strategy for lipid metabolism disorder-associated diseases.

Predicting Metabolite-Disease Associations Based on LightGBM Model

Metabolites have been shown to be closely related to the occurrence and development of many complex human diseases by a large number of biological experiments; investigating their correlation mechanisms is thus an important topic, which attracts many researchers. In this work, we propose a computational method named LGBMMDA, which is based on the Light Gradient Boosting Machine (LightGBM) to predict potential metabolite–disease associations. This method extracts the features from statistical measures, graph theoretical measures, and matrix factorization results, utilizing the principal component analysis (PCA) process to remove noise or redundancy. We evaluated our method compared with other used methods and demonstrated the better areas under the curve (AUCs) of LGBMMDA. Additionally, three case studies deeply confirmed that LGBMMDA has obvious superiority in predicting metabolite–disease pairs and represents a powerful bioinformatics tool.