The scarcity of complex intermediates in pharmaceutical research motivates the pursuit of reaction optimization protocols on submilligram scales. We report here the development of an automated ...flow-based synthesis platform, designed from commercially available components, that integrates both rapid nanomole-scale reaction screening and micromole-scale synthesis into a single modular unit. This system was validated by exploring a diverse range of reaction variables in a Suzuki-Miyaura coupling on nanomole scale at elevated temperatures, generating liquid chromatography-mass spectrometry data points for 5760 reactions at a rate of >1500 reactions per 24 hours. Through multiple injections of the same segment, the system directly produced micromole quantities of desired material. The optimal conditions were also replicated in traditional flow and batch mode at 50- to 200-milligram scale to provide good to excellent yields.
The separation of racemic compounds is important in many fields, such as pharmacology and biology. Taking advantage of the intrinsically strong chiral environment and specific interactions featured ...by biomolecules, here we contribute a general strategy is developed to enrich chirality into covalent organic frameworks (COFs) by covalently immobilizing a series of biomolecules (amino acids, peptides, enzymes) into achiral COFs. Inheriting the strong chirality and specific interactions from the immobilized biomolecules, the afforded biomolecules⊂COFs serve as versatile and highly efficient chiral stationary phases towards various racemates in both normal and reverse phase of high‐performance liquid chromatography (HPLC). The different interactions between enzyme secondary structure and racemates were revealed by surface‐enhanced Raman scattering studies, accounting for the observed chiral separation capacity of enzymes⊂COFs.
COF chirality: A general and efficient strategy has been developed to introduce chirality into covalent organic frameworks (COFs) by covalently immobilizing biomolecules into achiral COFs. The biomolecules⊂COFs can serve as chiral stationary phases for efficient chiral separation of a broad range of racemates.
Chlorogenic acid and caffeine are among the important components in coffee beans, determining the taste and aroma. In addition, phenols and antioxidants content possess vital health values. The main ...aim of this study is to determine the levels of caffeine and chlorogenic acid in several coffee samples of different origins and degrees of roasting. The coffee samples were extracted using hot water. The levels of caffeine and chlorogenic acid were quantified using high-performance liquid chromatography (HPLC) equipped with a diode array detector, a reverse phase system, and an ODS column (C18). Total phenol and antioxidant contents were previously determined for the same samples. The results showed that the highest content of caffeine was found in the medium roasted coffee (203.63 mg/L), and the highest content of chlorogenic acid content was found in the green coffee (543.23 mg/L). The results demonstrated a negative correlation between the chlorogenic acid levels with the degree of roasting, while it showed a positive correlation between the caffeine levels with the degree of roasting till a certain point where the levels dropped in the dark roasted coffee. The origin of coffee samples did not show any effect on any of the measured variables. Antioxidant effects of coffee samples were largely determined by chlorogenic acid content.
Untargeted methods are typically used in the detection and discovery of small organic compounds in metabolomics research, and ultra-high-performance liquid chromatography-high-resolution mass ...spectrometry (UHPLC-HRMS) is one of the most commonly used platforms for untargeted metabolomics. Although they are non-biased and have high coverage, untargeted approaches suffer from unsatisfying repeatability and a requirement for complex data processing. Targeted metabolomics based on triple-quadrupole mass spectrometry (TQMS) could be a complementary tool because of its high sensitivity, high specificity and excellent quantification ability. However, it is usually applicable to known compounds: compounds whose identities are known and/or are expected to be present in the analyzed samples. Pseudotargeted metabolomics merges the advantages of untargeted and targeted metabolomics and can act as an alternative to the untargeted method. Here, we describe a detailed protocol of pseudotargeted metabolomics using UHPLC-TQMS. An in-depth, untargeted metabolomics experiment involving multiple UHPLC-HRMS runs with MS at different collision energies (both positive and negative) is performed using a mixture obtained using small amounts of the analyzed samples. XCMS, CAMERA and Multiple Reaction Monitoring (MRM)-Ion Pair Finder are used to find and annotate peaks and choose transitions that will be used to analyze the real samples. A set of internal standards is used to correct for variations in retention time. High coverage and high-performance quantitative analysis can be realized. The entire protocol takes ~5 d to complete and enables the simultaneously semiquantitative analysis of 800-1,300 metabolites.
Diabetes is one of the metabolic diseases marked by hyperglycemia and is often accompanied by the occurrence of some complications. As a biomarker of oxidative stress, hydrogen peroxide (H2O2) has ...close association with the occurrence and development of diabetes and its complications. Unfortunately, there is no fluorescent probe reported for imaging H2O2 in diabetic mice. Here, a novel near-infrared (NIR) fluorescent probe named QX-B was designed and synthesized to detect H2O2. For the probe, the quinolinium-xanthene dye is used as the fluorophore and borate ester is chosen as the response group. After the addition of H2O2, a strong NIR fluorescence signal at 772 nm is observed. The probe not only shows high sensitivity with 10-fold enhancement but also displays excellent selectivity to H2O2 over other possible interfering species. In the meantime, the possible response mechanism of QX-B toward H2O2 was proposed and verified by the high-performance liquid chromatography (HPLC) experiment, mass spectra (MS) experiment, and density functional theory (DFT) calculation. Furthermore, based on the low cell cytotoxicity of QX-B, it has been applied in imaging exogenous and endogenous H2O2 in HeLa cells, HCT116 cells, 4T1 cells, and zebrafish successfully. More importantly, inspired by the performance of NIR fluorescence, QX-B has been used in monitoring H2O2 in diabetic mice for the first time. This provides very important information for the diagnosis and treatment of diabetes and its complications.
Proposed mechanism of the photoproduced charge transfer in 75NBA composite under visible-light irradiation.
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•Novel multifunctional dual Z-scheme NiFe2O4/Bi2WO6/AgI composite is ...constructed.•The heterostructure exhibits enhanced electron-hole separation by dual Z-scheme channel pathway.•NiFe2O4/Bi2WO6/AgI can also highly efficiently degrade CIP.•The in-depth mechanisms insight of charge separation.
Visible-light-driven (VLD) photocatalysis has aroused extensive attention due to their great potential in applications concerning energy crisis and environmental pollution. Hence, for the first time, VLD and magnetic recyclable dual Z-scheme NiFe2O4/Bi2WO6/AgI (NBA) composites were prepared via a hydrothermal method to obtain NiFe2O4/Bi2WO6 (NB) following an in situ deposition of AgI. The as-prepared NBA catalysts exhibit excellent photocatalytic performance for the degradation of ciprofloxacin (CIP) compared to the pristine NiFe2O4, Bi2WO6 or AgI under visible-light (VL) illumination. Among them, the 75%NiFe2O4/Bi2WO6/AgI (75NBA) composite exhibits optimal photocatalytic efficiency, which is 1.67, 1.51, 1.83 times higher than those of the pristine NiFe2O4, Bi2WO6 and AgI within 60 min, respectively. The high catalytic efficiency may be ascribed to the synergistic effect of the increased VL harvesting and dual Z-Scheme transmission paths in 75NBA system. Furthermore, trapping experiments and electrochemical impedance spectroscopy (ESR) analysis verify the co-existing of OH and O2− in the 75NBA photocatalytic system. Additionally, the magnetic 75NBA can be rapidly separated from water by an external magnet. Based on the results from High performance liquid chromatography-mass spectrometry (HPLC-MS) analysis, four path ways towards the degradation of CIP are proposed. The highly efficient photocatalytic activity and magnetically reproducibility suggest that it is expected to be used in antibiotic wastewater treatment.
Ultra-high-performance liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS) variants currently represent the best tools to tackle the challenges of complexity and lack of ...comprehensive coverage of the metabolome. UHPLC offers flexible and efficient separation coupled with high-sensitivity detection via HRMS, allowing for the detection and identification of a broad range of metabolites. Here we discuss current common strategies for UHPLC-HRMS-based metabolomics, with a focus on expanding metabolome coverage.
A novel 3D metal–organic framework (MOF){Tb3(CBA)2(HCOO)(μ3-OH)4(H2O)·2H2O·0.5DMF} n (S-1) was synthesized by the solvothermal method. The crystal structure indicates that Tb4O4 cubane clusters ...self-assemble into an infinite chain by sharing vertex, which is further linked to adjacent chains through 1,1-cyclobutanedicarboxylic acid ligand (H2CBA), resulting in a honeycomb arrayed framework. S-1 possesses excellent water stability and still retains intact structure after exposure to water for 10 weeks or boiling water for 10 weeks. Interestingly, S-1 acts as a luminescence sensor to selectively and sensitively detect quercetin with the limit of detection (LOD) as low as 0.23 ppm (7.6 × 10–7 M). The relationship between relative luminescence intensity and concentration obeys linear in the range of 0–300 ppm (0–993 μM), which allows quantitative detection of quercetin. Importantly, S-1 can be reused at least six times with almost no change in luminescent intensity. Compared with the high performance liquid chromatography–mass spectrometry (HPLC–MS) method, S-1 was used to determine the content of quercetin in onionskin and apple peel samples with satisfactory results. Furthermore, a portable S-1 test paper is also developed and expected to be applied in practice. To our knowledge, S-1 is the first example of MOFs as luminescent sensor for quercetin.
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