Fluorescence determination of quercetin in food samples using polyhedron-shaped MOF@MOF(NUZ-8) based on NH2-UiO-66 and ZIF-8.

A new metal-organic framework compound (MOF@MOF, NUZ-8) comprised of NH2-UiO-66 and ZIF-8 under the polyvinylpyrrolidone (PVP) as the structure modifier was synthesized through an internal extended growth method (IEGM). The resulting NUZ-8 emerged the unreported unique polyhedron shape and showed considerable specific surface area (1466.1862 m2/g), excellent adsorption capacity, and fluorescence. NUZ-8 was used as a probe for the rapid optical detection of natural antioxidant quercetin (QCT). Its outstanding selectivity and sensitivity to QCT are derived from the fact that NH2-UiO-66 acted as an optical tentacle to perceive QCT in virtue of its luminescence advantages, and ZIF-8 realized the selective enrichment of the QCT through its electron-rich framework structure. The experiments were carried out at an excitation wavelength of 335 nm and an emission wavelength range of 370-530 nm. Under conditions of the investigation, this probe realized the rapid detection of QCT and considerable adsorption capacity with wide linearity (0.3-80 µM), a low detection limit (0.14 µM), and acceptable recoveries (84.0-97.0%) in red wine samples, properties which were superior to many other detection platforms. The synthesis and the use of the above polyhedral composite provide guidance for the application of the IEGM in enhancing chemical sensing and instant determination of drugs.Graphical abstract Flow chart of this paper.

Enantioseparation of the Six Important Intermediates of Homoharringtonine With Immobilized Cellulose Chiral Stationary Phase.

A new liquid chromatographic method has been developed for the chiral separation of the enantiomers of intermediates in the preparation of the ester side-chain of homoharringtonine. The enantiomers were separated by a Chiralpak IC (250 × 4.6 mm, 5 µm) in normal phase high-performance liquid chromatography (HPLC). Four compounds were baseline resolved. By comparing the chromatographs of racemates and single enantiomers of the six intermediates, the enantiomeric excess values of the single enantiomers were evaluated, and the elution orders of the enantiomers were established.

Surface molecularly imprinted polymers fabricated by differential UV-vis spectra and reverse prediction method for the enrichment and determination of sterigmatocystin.

A novel magnetic molecularly imprinted polymers (MMIPs) with a new functional monomer Triallyl isocyanurate was synthesized successfully to enrich and detect sterigmatocystin (STG) in wheat samples. The differential UV-vis spectra and the reverse prediction method were selected to achieve the optimal synthesis conditions of the MMIPs, which were characterized well. The adsorption experiment showed that MMIPs have high selectivity and sensitivity. A magnetic solid phase extraction combined with high performance liquid chromatography (MSPE-HPLC) method based on the MMIPs was successfully established with the optimal extraction condition. The linear range and RSD were 1.8-25 ng·g-1 and 2.6-4.1%, respectively. The recovery of this method was 87.6-96.9% and the limit of detection (LOD) was 0.63 ng·g-1. The excellent sensitivity and selectivity of this method were confirmed by experiment of the extraction and detection of STG in wheat extracts. This work extends the use of molecular imprinting in mycotoxins applications.

Human Saliva Metabolome for Oral Lichen Planus Biomarker Identification.

BACKGROUND: Oral Lichen Planus (OLP) is one of the most common oral mucosal diseases. However, the current diagnostic method for OLP has limitations, and sometimes it is easy to be misdiagnosed. Salivary metabolomics may provide new ideas for the diagnosis of OLP. OBJECTIVE: To identify the biomarkers for the early detection of OLP. METHODS: A non-targeted metabolomic analysis method was established based on UHPLC-Q-Orbitrap HRMS (Ultra-performance liquid chromatography-quadrupole/orbitrap high resolution mass spectrometry) to analyze the differential metabolites in saliva samples of patients with OLP and healthy subjects. Saliva samples were collected from 120 OLP patients and 125 healthy subjects. RESULTS: A total of 19 differential metabolites were identified, including 6 amino acid metabolites, 2 carnitines, 2 lipid metabolites and 9 other metabolites. The integrated biomarkers were constructed by 3 metabolites according to Receiver Operating Characteristic (ROC). Meanwhile, multiple metabolic pathways were found to be involved in the occurrence and development of OLP. CONCLUSION: Metabolomics can be used to characterize the characteristics of metabolic disorders in patients with OLP, which is also helpful to the early diagnosis of OLP and reveal the pathological process of OLP.

Selective recognition and enrichment of carbamazepine in biological samples by magnetic imprinted polymer based on reversible addition-fragmentation chain transfer polymerization.

A well-defined molecularly imprinted polymer (Fe3O4@CS@MIP) was synthesized via reversible addition-fragmentation chain transfer polymerization for magnetic solid-phase extraction coupled with high-performance liquid chromatography-diode array detector to detect carbamazepine (CBZ) in biological samples. The composition of Fe3O4@CS@MIP was selected by a two-step screening method. 4-vinyl pyridine, divinylbenzene and dimethylformamide were chosen as the functional monomer, cross-linker and porogen, respectively. The imprinted layer was coated on the surface of the chain transfer agent-modified magnetic chitosan nanoparticles. The prepared Fe3O4@CS@MIP was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller measurement and vibrating sample magnetometer. The results indicated that Fe3O4@CS@MIP had a large surface area (265.8 m2/g), high saturation magnetization (19.88 emu/g) and uniform structure. Besides, the binding property of the Fe3O4@CS@MIP was studied in detail. The Fe3O4@CS@MIP showed high imprinting factor (IF = 4.83) and desirable adsorption capacity (323.10 µmol/g) to CBZ. Under the optimum conditions, the developed method exhibited excellent linearity (R2>0.999) in the range of 0.01-0.5 mg/L and 1.0-30.0 mg/L, and the limits of detection were 1.0 µg/L and 9.6 µg/L for the urine and serum samples, respectively. Good recoveries (88.22%-101.18%) were obtained with relative standard deviations less than 4.83%. This work provided a practical approach for the selective extraction and detection of CBZ in real samples.

Enantioseparation of Six Antihistamines with Immobilized Cellulose Chiral Stationary Phase by HPLC.

A stereoselective high performance liquid chromatography method has been developed for the chiral separation of the enantiomers of six antihistamines, doxylamine, carbinoxamine, dioxopromethazine, oxomemazine, cetirizine and hydroxyzine. The effects of mobile phase additive, column temperature and flow rate on the retention time and resolution were studied. Enantiomeric separation of cetirizine, doxylamine and hydroxyzine were achieved on cellulose tris-(3,5-dichlorophenylcarbamate) immobilized on silica gel chiral stationary phase known as Chiralpak IC (RS = 3.74, RS = 1.85 and RS = 1.74, respectively).