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Chiral covalent organic frameworks (CCOFs) featuring chirality, stability, and good porosity have attracted a considerable amount of attention due to their important applications, such as asymmetric catalysis, chiral separation, and chiral recognition. In this study, a β-cyclodextrin (β-CD) covalent organic framework (β-CD-COF) diluted with polysiloxane OV-1701 was explored as a novel chiral stationary phase (CSP) for gas chromatography (GC) separation of racemates. The β-CD-COF coated capillary column had excellent selectivity, not only for the separation of linear alkanes, linear alcohols, fatty acid methyl esters mixture, the Grob mixture and positional isomers, but also for the resolution of chiral compounds, including chiral alcohols, aldehydes, ethers, and amino acid derivatives. In addition, the β-CD-COF-coated capillary column presented good repeatability and reproducibility. This work indicated the great potential of the CCOFs coated capillary column for the chromatographic separation of enantiomers.

Hydrogen-bonded organic frameworks (HOFs) are two dimensional (2D) or three dimensional (3D) porous crystalline materials constructed by Hydrogen bond interaction. In recent years, a variety of functional HOF materials have been successfully synthesized and used in structural identification, environmental pollutant removal, chiral resolution, drug delivery, fluorescence sensing, etc. Here, we first reported that a HOF to coated capillary column for high-resolution gas chromatographic separation of a wide range of analytes, including n-alkanes, n-alcohols, polycyclic aromatic hydrocarbons, and positional isomers, especially for racemates, the HOFs column showed excellent separation repeatability and reproducibility. The relative standard deviation (RSD) values for the retention times were in the range of 0.37-2.43% for run to run (n = 3), 0.38-2.51% for day-to-day (n = 3), and 0.31-2.54% for column-to-column (n = 3), respectively. Moreover, we applied density-functional theory to calculate the adsorption of enantiomers in HOF structures. This work proved that the HOFs had great application prospects as stationary phase in gas chromatography.

Herein, we describe a new chiral amorphous metal-organic polyhedra used as the stationary phase for high-resolution gas chromatography (GC). The chiral stationary phase was coated onto a capillary column via a dynamic coating process and investigated for a variety of compounds. The experimental results showed that the chiral stationary phase exhibits good selectivity for linear alkanes, linear alcohols, polycyclic aromatic hydrocarbons, isomers, and chiral compounds. In addition, the column has the advantages of high column efficiency and short analysis time. The present work indicated that amorphous metal-organic polyhedra have great potential for application as a new type of stationary phase for GC.

Chiral metal-organic cages (MOCs) are a new type of porous materials with unique molecular recognition ability, which have received research attention as a chiral stationary phase (CSP) for gas chromatography (GC). Herein, we report the detailed investigation of a chiral MOC ([Cu12(LPA)12(H2O)12], PA = L-phenylalanine, MOC-PA) as a novel stationary phase for GC separations. The MOC-PA capillary column exhibited a high-resolution performance for a wide range of analytes, including n-alkanes, n-alcohols, esters, aromatic compounds and the Grob mixture, positional isomers and racemates. In particular, MOC-PA coated column displayed good resolution and performance for amino acid derivatives. Moreover, the MOC-PA column showed excellent separation repeatability and reproducibility. The relative standard deviation (RSD) values for the retention times were in the range of 0.16-0.30% for run to run (n = 3), 0.31-0.77% for day-to-day (n = 3), and 3.6-4.7% for column-to-column (n = 3), respectively. The experimental results showed that MOC-PA had great potential as a GC stationary phase.

In this paper, molecularly imprinted photonic crystal hydrogels (MIPHs) were prepared by combining photonic crystals with molecular imprinting technology. The MIPHs were used as optical sensors for the rapid reorganization and detection of melamine in water samples. In this experiment, melamine was used as a template molecule, and the MIPHs were prepared by successive self-assembly, polymerization, and template removal. Morphological characterization by scanning electron microscopy (SEM) showed that the MIPHs possessed a highly ordered three-dimensional (3D) macroporous structure containing nanocavities. As optical sensors, the MIPHs were able to transform molecular recognition events into fluorescence signals for rapid and highly selective and sensitive recognition of the target molecule. Based on color changes of the MIPHs, the target analyte could be quickly identified by analysis with image software or even by observation with the naked eye. Under optimal conditions, the Bragg diffraction peak of the MIPHs shifted from 563 to 608 nm when exposed to melamine in mass concentrations of 10-11 to 10-6mol/L, whereas there were no obvious peak shifts when it was exposed to structural analogues of melamine.

In this work, a novel polymer membrane molecularly imprinted on a silanized glass substrate was prepared. Lysozyme was chosen as the template protein, and acrylamide and N,N'-methylenebisacrylamide were used as the functional monomer and crosslinking agent, respectively. The adsorption equilibrium time, maximum adsorption capacity, specific recognition ability, reusability, and application of the prepared lysozyme-imprinted polymer membrane were investigated experimentally. The prepared polymer membrane exhibited special recognition ability and could quickly adsorb lysozyme. Under optimal conditions, the adsorption equilibrium time of the prepared polymer membrane for lysozyme was 5 min, and the adsorption behavior conformed to the Langmuir adsorption model; the theoretical maximum adsorption capacity was 42.5 mg/g, and the adsorption capacity for an egg sample was 30 mg/g. Additionally, the polymer membrane showed a high selectivity toward the template protein, lysozyme, and exhibited no obvious adsorption of several interfering proteins; the imprinting factor was 3.0. The maximum adsorption capacity of the polymer membrane decreased by 5% after being reused five times. The polymer membrane was used for the adsorption of lysozyme in samples, and good results were obtained. This strategy has potential for the separation and enrichment of target proteins in complex biological samples.

Hydrophilic uridine molecularly imprinted core-shell structured polymers (MIPs) were prepared via the distillation precipitation polymerization method using uridine, methyl methacrylate, ethylene glycol dimethacrylate, and 2, 2-azobisisobutyronitrile as the template molecule, functional monomer, cross-linker, and initiator, respectively. The adsorption kinetic behavior, equilibrium, and selectivity of uridine onto the MIPs were investigated by conducting a series of batch adsorption experiments. The results showed that the pseudo-first-order kinetic model provided a good correlation for the adsorption of uridine onto MIPs. The linear correlation coefficient R2 was 0.9884. The Langmuir and Freundlich modeling of the adsorption showed that the adsorption of the imprinted molecule uridine onto MIPs was fitted well to the Freundlich equation. The R2 value was 0.980. The separation capability of the MIPs to uridine and its analog was evaluated as HPLC column filling. The MIPs chromatographic column has a selec...

Saliva protein separation by one-step aqueous two-phase extraction (ATPE) in the system of 15% (mass ratio if not specified) PEG-4000/8% NaH2PO4 was presented. The proteins extracted from the top and bottom phases were separated and characterized by high performance liquid chromatography (HPLC) respectively. Under the optimized gradient elution procedure, more saliva protein peaks in the two phases were shown. Saliva protein peaks in 50 min gradient were divided into ten specific groups which were classified into six sections based on the protein distribution in the top and bottom phases. Then, the top or bottom phase was performed the second step ATPE. Possible reasons for protein partition and retention difference are discussed briefly. Results show that some proteins can be separated completely in one-step ATPE, while some can be separated in the following two-step ATPE. The combination of two steps ATPE and HPLC provides a new way to achieve selective separation.

The thermal stability and pyrolysis pathway of liquid crystalline polysiloxanes containing benzyl ether and biphenyl mesogen were investigated by pyrolysis gas chromatography (Py-GC) and Py-GC/MS. The polysiloxanes were stable up to 250 °C.

Molecularly imprinted polymers (MIPs) with excellent molecular recognition ability have been used in chemical sensors, chromatographic separation and biochemical analyses. Thymidine is an important part of DNA for biomolecular recognition and the intermediate of many medicines. The polymers imprinted with the template of thymidine and 5'-Otosylthymidine have been prepared, using a non-proton solvent, acetonitrile as the porogen. Direct imprinting with thymidine could not form strong molecular interaction sites in this system. Relative MIPs were obtained by bulk polymerization and their adsorption capacities were investigated. The adsorption capacities of MIP (P 2 ) and nonimprinted polymer (P 20 ) for thymidine are 0.120 mg•g -1 and 0.103 mg•g -1 , respectively. The imprinting factor is 1.17. As 5'-O-tosylthymidine is more soluble than thymidine moiety in acetonitrile and give rise to more sites of molecular recognition. The results demonstrated that the imprinted polymers were able to bind and recognize thymidine moderately in acetonitrile. MIPs imprinted with 5'-O-tosylthymidine like nature enzymes displayed some recognition ability to its analogues. The insoluble derivatives in the non-proton solvent can be an effective template to prepare efficient imprinting recognition sites.

The thermal stability and pyrolysis mechanism of heptakis[3-O-methyl-2,6- di -O-(methoxybenzyl)]-β-cyclodextrin (MMBCD) were investigated by pyrolysis gas chromatography (Py-GC) and Py-GC/MS. MMBCD was stable up to 300 °C. Several optical and positional isomers were baseline separated using MMBCD as the stationary phase.