Comparison of Alternative Protein Hydrogels for Delivering Myricetin: Interaction Mechanism and Stability Evaluation.

Food protein carriers from different sources might have distinct stabilizing and enhancing effects on the same small molecule. To elucidate the molecular mechanism, five different sourced proteins including soy protein isolates (SPIs), whey protein isolates (WPIs), edible dock protein (EDP), Tenebrio molitor protein (TMP), and yeast protein (YP) were used to prepare protein hydrogels for delivering myricetin (Myr). The results suggested that the loading capacity order of Myr in different protein hydrogels was EDP (11.5%) > WPI (9.3%) > TMP (8.9%) > YP (8.0%) > SPI (7.6%), which was consistent with the sequence of binding affinity between Myr and different proteins. Among five protein hydrogels, EDP had an optimum loading ability since it possessed the highest hydrophobic amino acid content (45.52%) and thus provided a broad hydrophobic cavity for loading Myr. In addition, these protein-Myr composite hydrogels displayed the core-shell structure, wherein hydrogen bonding and hydrophobic interaction were the primary binding forces between proteins and Myr. Moreover, the thermal stability, storage stability, and sustained-release properties of Myr were significantly enhanced via these protein delivery systems. These findings can provide scientific guidance for deeper utilization of food alternative protein sources.

Regulation Mechanism of Phenolic Hydroxyl Number on Self-Assembly and Interaction between Edible Dock Protein and Hydrophobic Flavonoids.

In this study, galangin (Gal), kaempferol (Kae), quercetin (Que), and myricetin (Myr) were chosen as the representative flavonoids with different phenolic hydroxyl numbers in the B-ring. The edible dock protein (EDP) was chosen as the new plant protein. Based on this, the regulation mechanism of the phenolic hydroxyl number on the self-assembly behavior and molecular interaction between EDP and flavonoid components were investigated. Results indicated that the loading capacity order of flavonoids within the EDP nanomicelles was Myr (10.92%) > Que (9.56%) > Kae (6.63%) > Gal (5.55%). Moreover, this order was consistent with the order of the hydroxyl number in the flavonoid's B ring: Myr (3) > Que (2) > Kae (1) > Gal (0). The micro morphology exhibited that four flavonoid-EDP nanomicelles had a core-shell structure. In the meantime, the EDP encapsulation remarkably improved the flavonoids' water solubility, storage stability, and sustained release characteristics. During the interaction of EDP and flavonoids, the noncovalent interactions including van der Waals forces, hydrophobic interaction, and hydrogen bonding were the main binding forces. All of the results demonstrated that the hydroxyl number of bioactive compounds is a critical factor for developing a delivery system with high loading ability and stability.

Self-assembly and interaction mechanisms of edible dock protein and flavonoids regulated by the phenolic hydroxyl position.

In this study, chrysin (Chr), baicalein (Bai), apigenin (Api) and galangin (Gal) were selected as the representative flavonoids with different position of phenolic hydroxyl groups, and edible dock protein (EDP) was used as a material to construct delivery system. Subsequently, the molecular interactions and functional properties of flavonoids-loaded EDP nanomicelles were investigated. Results exhibited that hydrogen bond, hydrophobic interaction and van der Waals force were the main driving forces for self-assembly of flavonoids and EDP molecules. Meanwhile, this self-assembly remarkably enhance the storage and digestion stability of flavonoid compounds. Among four flavonoids, the order of loading ability was: Api > Gal > Bai > Chr. Herein, Api had a largest loading capacity (6.74%) because of its active phenolic hydroxyl group in ring B. These results suggested that the position of phenolic hydroxyl groups in flavonoids is a key factor to regulate its self-assembly with protein molecules.

Effect of Pathogenesis-Based Individualized Thrombectomy on Treatment Result and Prognosis of Acute Intracranial Large-Artery Occlusion Patients.

AIM: To explore the effect of pathogenesis-based individualised thrombectomy on the clinical results and prognoses of acute intracranial large-artery occlusion. MATERIAL AND METHODS: A total of 151 patients were included in this prospective study and divided into the control group (stent thrombectomy, 53 cases), a direct aspiration first pass technique (ADAPT) group (52 cases) and the stent group (stent thrombectomy or a combination of stent thrombectomy and ADAPT, 46 cases) based on whether stent or ADAPT was used. We compared and analysed the patients? general information, the National Institutes of Health Stroke Scale (NHISS) score at admission, the time between the end of arteriography and revascularisation, the number of thrombectomies, the modified Rankin scale (mRS) score at three months and complications in the three groups. RESULTS: Compared with the control group, the time between the end of arteriography and revascularisation in the ADAPT group was significantly reduced (p < 0.05), and the patency rate after one thrombectomy significantly increased (p < 0.05). The positive prognosis rate was significantly increased in the stent and ADAPT groups compared with the control group (p < 0.05). CONCLUSION: The application of the ADAPT technique in patients with embolism-induced cerebral infarction can reduce the time of revascularisation. The use of stents in patients with atherosclerosis-induced cerebral infarction can increase the patency rate after one thrombectomy.

Cumulative effects of temperature on blood pressure during pregnancy: A cohort study of differing effects in three trimesters.

BACKGROUND: Little is known about the non-linear cumulative effects of temperature on blood pressure (BP) during pregnancy. We investigated the differing effects of daily ambient temperature on BP for up to 30 days in three trimesters. METHODS: The first, second, and third trimester analyses included 2547, 2299, and 2011 pregnant women, respectively, from a prospective cohort in Nanjing from January 2017 to January 2020. BP was measured at each follow-up visit. The individual daily temperature exposures were calculated for 30 days prior to the follow-up date. The Distributed Lag Non-linear Model was used to investigate the relationship between temperature and BP in each trimester. RESULTS: Temperatures under 15 °C elevate systolic, diastolic BP, and mean arterial pressure (SBP, DBP, and MAP) in the first trimester, while temperatures above 15 °C reduce SBP in the second and third trimesters. By using Distributed Lag Linear Models, we estimated that with a 1 °C decrease in daily temperature, the SBP and DBP increased by 0.32 (95 % CI: 0.12, 0.52) and 0.23 (95 % CI: 0.07, 0.39) mmHg, respectively, in the first trimester with a 20-day cumulative lag, while with a 1 °C increase in daily temperature, the SBP decreased by 0.23 (0.35, 0.10) mmHg in the third trimester with a 30-day cumulative lag. The significant effects of temperature mainly manifested between 2 and 4 weeks of exposure. CONCLUSIONS: Temperature has different effects on BP over three trimesters. Protective measures to reduce cold-related BP rise will help reduce the risk of hypertensive disorders of pregnancy.

Immobilized Lipase Based on Hollow Mesoporous Silicon Spheres for Efficient Enzymatic Synthesis of Resveratrol Ester Derivatives.

Enzymatic esterification of resveratrol is crucial for its potential application in lipophilic foods and drugs. However, the poor activity of the free enzyme hinders the reaction. In this work, the highly efficient enzymatic synthesis of resveratrol ester derivatives was achieved by immobilized lipase on hydrophobic modified hollow mesoporous silicon spheres (HMSS-C8). We preliminarily explored the use of Candida sp. 99-125 lipase (CSL) for the acylation of resveratrol, with a regioselectivity toward 3-OH- over 4'-OH-acylation. HMSS-C8 provided ideal accommodation for CSL with a loading capacity of up to 652 mg/g. The catalytic efficiency of CSL@HMSS-C8 was 15 times higher than that of free CSL, and the conversion of resveratrol reached 98.7% within only 2 h, which is the fastest value recorded in the current literature. After 10 cycles, the conversion remained up to 86.3%. Benefiting from better lipid solubility, the relative oxidation stability index values of oil containing monoester derivatives were 43.1%-68.8% and 23.9%-33.2% higher than that of refined oil and oil containing resveratrol, respectively. This research provides a new pathway for efficient enzymatic synthesis of resveratrol ester derivatives and demonstrates the potential application of resveratrol monoester derivatives as a group of excellent lipid-soluble antioxidants.

Preparation of Immobilized Lipase Based on Hollow Mesoporous Silica Spheres and Its Application in Ester Synthesis.

In this study, Candida rugosa lipase (CRL) was immobilized into modified hollow mesoporous silica (HMSS) materials with different hydrophobicity. Among propyl-(C3), phenyl-(C6), octyl-(C8), and octadecyl-(C18) modified HMSS as well as native HMSS, taking advantage of more hydrophobic microenvironment, the HMSS-C18-CRL showed exceptional performance in enzymatic esterification reaction. Using the novel HMSS-C18 with immobilized CRL (HMSS-C18-CRL), we investigated the esterification of phytosterols with polyunsaturated fat acid (PUFA) in a solvent-free system for the production of phytosterols esters. Response surface methodology (RSM) was applied to model and optimize the reaction conditions, namely, the enzyme load (5⁻25%), reaction time (10⁻110 min), molar ratio of α-linolenic acid (ALA)/phytosterols (1:1⁻7:1) and represented by the letters E, T, and M respectively. Best-fitting models were successfully established by multiple regressions with backward elimination. The optimum production was achieved at 70 min for reaction time, 20% based on the weight of substrate for enzyme loading, and 5.6:1 for ALA/phytosterols molar ratio. Under optimized conditions, a conversion of about 90 ± 2% was achieved. These results indicated that HMSS-C18-CRL demonstrates to be a promising catalyst and can be potentially applied in the functional lipid production.

Pravastatin alleviates lipopolysaccharide-induced placental TLR4 over-activation and promotes uterine arteriole remodeling without impairing rat fetal development.

Preeclampsia is associated with over-activation of the innate immune system in the placenta, in which toll-like receptor 4 (TLR4) plays an essential part. With their potent anti-inflammatory effects, statins have been suggested as potential prevention or treatment of preeclampsia, although evidence remains inadequate. Herewith, we investigated whether pravastatin could ameliorate preeclampsia-like phenotypes in a previously established lipopolysaccharide (LPS)-induced rat preeclampsia model, through targeting the TLR4/NF-κB pathway. The results showed that pravastatin reduced the blood pressure [maximum decline on gestational day (GD) 12, (101.33±2.49) mmHg vs. (118.3±1.37) mmHg, P<0.05] and urine protein level [maximum decline on GD9, (3,726.23±1,572.86) µg vs. (1,991.03±609.37) µg, P<0.05], which were elevated following LPS administration. Pravastatin also significantly reduced the rate of fetal growth restriction in LPS-treated rats (34.10% vs. 8.99%, P<0.05). Further pathological analyses suggested a restoration of normal spiral artery remodeling in preeclampsia rats by pravastatin treatment. These effects of pravastatin were associated with decreased TLR4/NF-κB protein levels in the placenta and IL-6/MCP-1 levels in serum. Additionally, no obvious abnormalities in fetal liver, brain, and kidney were found after administration of pravastatin. These results provide supportive evidence for use of pravastatin in preventing preeclampsia.

[Emission Factors of Heavy Metals in Size-resolved Particles Emitted from Residential Coal Combustion].

Based on a dilution sampling system and domestic burning tests, size-segregated particles emitted from burning of three kinds of honeycomb coals (in view of flaming and smoldering burning conditions) and four kinds of raw coals, were collected by cascade impactors (FA-3). The contents of V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Sb, and Pb were analyzed to get their emission factors (EFs) in different particle size fractions. Results indicated that:① Zn and Pb dominated the emitted mass of heavy metals from chunk (53.16%-65.76%) and honeycomb (96.08% in 0.43 µm) during the flaming combustion condition. However, the emission of Ni was increased from 30.70% to 52.36% in the smoldering condition. Thus, combustion condition may affect the composition of heavy metals in particle matters. ② In the flaming condition, both chunk and honeycomb emission factors of heavy metals were concentrated under 1.1 µm, while the larger sized particles in the range of 5.8-10 µm were distributed. So, heavy metal components may shift to the larger size of the particles at lower combustion temperatures. ③ Fine particle matters(PM) was divided into three categories based on the size distribution of 11 kinds of heavy metal emission factors. The maximum emission values of As and V fell under the PM size category of 5.8-10 µm. The fourth cycle transition metal elements, such as Cr, Mn, Cu, Ni, and Co, fell in the range of 1.1-2.1 µm and these elements represented similar emission characteristic features. Other elements, such as Pb, Sb, Cd, and Zn, were concentrated in sizes less than 0.43 µm. ④ The additive in the honeycomb during the process may import several kinds of heavy metals and may change the combustion temperature, which remodels the mechanism of heavy metal emission. Thus, honeycomb coal may emit different heavy metals under different combustion conditions.The heavy metal emission mechanism during honeycomb coal combustion needs further investigation and the emission reduction effects (especially of heavy metals) needs to be re-estimated.

[Size-resolved Emission Factors of Carbonaceous Particles from Domestic Coal Combustion in China].

China is one of the most important contributors to the global burden of carbonaceous aerosols, of which domestic coal combustion occupies a large fraction. Uncertainty in the emission factors (EFs) directly influences the accuracy of corresponding emission inventories. In the present study, based on domestic burning tests with a dilution sampling system, nine size-segregated particle classes emitted from the burning of three kinds of honeycomb coals (under flaming and smoldering burning conditions) and four kinds of chunk coals, including bituminous and lignite, were collected via a cascade impactor (FA-3). Organic and elemental carbon (OC and EC, respectively) were analyzed using the thermal-optical method. The EFs of particulate matter (PM), OC, and EC for nine size ranges were obtained. For honeycomb coals, the EFs of OC and EC in PM2.1 were 0.07 g·kg-1 and 0.002 g·kg-1, respectively, under flaming burning conditions and 0.10 g·kg-1 and 0.001 g·kg-1, respectively, under smoldering burning conditions. Carbonaceous particles exhibited higher EFs under flaming burning conditions. For chunk coals, the EFs of OC and EC in PM2.1 were 1.4 g·kg-1 and 0.02 g·kg-1, respectively, which are about one magnitude higher than those for honeycomb coal burning. Particulate matter and its associated carbonaceous components preferred to concentrate in fine particles. The EFs of carbonaceous components peaked at the size of ≤ 0.43 µm and 0.43-0.65 µm for honeycomb coal burning and chunk coal burning, respectively.

Genetic polymorphisms of CCL1 rs2072069 G/A and TLR2 rs3804099 T/C in pulmonary or meningeal tuberculosis patients.

CCL1, one of the members of the CC chemokine family, is an inflammatory mediator that stimulates the migration of human monocytes. CCL1 expression is induced by Mycobacterium tuberculosis and TLR ligands in macrophage. TLR2 plays critical role in host immune response against M. tuberculosis infection by regulating the macrophage activation and cytokine secretion. M. tuberculosis causes different clinical forms of tuberculosis (TB) disease. Single-nucleotide polymorphisms (SNPs) in the CCL1 gene and TLR2 gene may be associated with the development of different clinical forms of TB, depending on the different immune mechanisms. This study was to evaluate the possible association between CCL1 rs2072069 G/A or/and TLR2 rs3804099 T/C (T597C) polymorphisms and pulmonary tuberculosis (PTB) or/and tuberculous meningitis (TBM) in a sample of the Chinese adult population. A case-control study was designed to compare the allele frequency and genotype distribution between control (n=386) and TB (n=341) who had either PTB (n=230) or TBM (n=111). The genotype typing was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. TLR2 variant genotype 597CC was associated with susceptibility to PTB rather than to TBM. In the male PTB subgroup, 597CC genotype was identified in a higher rate, compared with male control subgroup. This study demonstrates that T597C polymorphism of TLR2 is a risk factor for susceptibility to PTB rather than to TBM in a sample of Chinese adult population. Patient gender may affect the outcome of M. tuberculosis infection. TLR2 gene may influence the development of PTB and TBM by different immune mechanisms.

Production of novel "functional oil" rich in diglycerides and phytosterol esters with "one-pot" enzymatic transesterification.

Diglycerides and phytosterol esters are two important functional lipids. Phytosterol esters mixed with dietary diglyceride could not only influence body weight but also prevent or reverse insulin resistance and hyperlipidemia. In this study, a kind of novel "functional oil" rich in both diglycerides and phytosterol esters was prepared with "one-pot" enzymatic transesterification. First, lipase AYS (Candida rugosa) was immobilized on the porous cross-linked polystyrene resin beads (NKA) via hydrophobic interaction. The resulting immobilized AYS showed much better transesterification activity and thermal stability to freeways. On the basis of the excellent biocatalyst prepared, a method for high-efficiency enzymatic esterification of phytosterols with different triglycerides to produce corresponding functional oils rich in both diglycerides and phytosterol esters was developed. Four functional oils rich in both diglycerides and phytosterol esters with conversions >92.1% and controllable fatty acid composition were obtained under the optimized conditions: 80 mmol/L phytosterols, 160 mmol/L triglycerides, and 25 mg/mL AYS@NKA at 180 rpm and 50 °C for 12 h in hexane. The prepared functional oil possessed low acid value (≤1.0 mgKOH/g), peroxide value (≤2.1 mmol/kg), and conjugated diene value (≤1.96 mmol/kg) and high diglyceride and phytosterol ester contents (≥10.4 and ≥20.2%, respectively). All of the characteristics favored the wide application of the functional oil in different fields of functional food.

Lipase immobilization on hyper-cross-linked polymer-coated silica for biocatalytic synthesis of phytosterol esters with controllable fatty acid composition.

In this study, a novel mixed-mode composite material, SiO(2)@P(MAA-co-VBC-co-DVB), was prepared via the hyper-cross-linking of its precursor, which was produced via suspension polymerization in the presence of SiO(2) particles. Candida rugosa lipase (CRL) was immobilized on the SiO(2)@P(MAA-co-VBC-co-DVB) particles via hydrophobic and weak cation-exchange interaction. The resulting immobilized CRL showed much better thermal stability and reusability in comparison to free CRL. On the basis of the excellent biocatalyst prepared, a method for high-efficiency enzymatic esterification of phytosterols with different fatty acids to produce the corresponding phytosterol esters was developed. Six phytosterol esters with conversions above 92.1% and controllable fatty acid composition were obtained under the optimized conditions: 80 µmol/mL phytosterols, 160 µmol/mL linolenic acid, and 15 mg/mL CRL@HPCS at 300 rpm and 50 °C for 7 h in 30 mL of isooctane. The prepared phytosterol esters possessed a low acid value (≤0.86 mg of KOH/g), peroxide value (≤3.3 mequiv/kg), and conjugated diene value (≤1.74 mmol/kg) and high purity (≥97.8%) and fatty solubility (≥28.9 g/100 mL). All the characteristics favored the wide application of phytosterol esters with controllable fatty acid composition in different fields of functional food.

Ultrasonic pretreatment for lipase-catalyed synthesis of phytosterol esters with different acyl donors.

This study is focused on the enzymatic esterification of phytosterols with different acyl donors to produce the corresponding phytosterol esters catalyzed by Canadia sp. 99-125 lipase under ultrasound irradiation. An ultrasonic frequency of 35 kHz, power of 200 W and time of 1h was determined to guarantee satisfactory degree of esterification and lipase activity. The influence of temperature, substrates concentration and molar ratio was investigated subsequently. The optimum production was achieved in isooctane system at 60°C with phytosterol concentration of 150 µmol/mL and phytosterol to fatty acid molar ratio of 1:1.5, resulting in a phytosterol esters conversion of above 85.7% in short reaction time (8h). Phytosterols esters could also be converted in high yields to the corresponding long-chain acyl esters via transesterification with triacylglycerols (above 90.3%) under ultrasound irradiation. In optimum conditions, the overall esterification reaction rate using the ultrasonic pretreatment process was above 2-fold than that of mechanical stirring process without damage the lipase activity.

Immobilization of Candida rugosa lipase on hydrophobic/strong cation-exchange functional silica particles for biocatalytic synthesis of phytosterol esters.

In this work, mixed-mode silica particles functionalized with octyl and sulfonic acid groups was conveniently prepared by co-bonding a mixture of n-octyltriethoxysilane and 3-mercaptopropyltriethoxysilane and then oxidized with hydrogen peroxide. Candida rugosa lipase (CRL) was immobilized on the mixed-mode silica particles via hydrophobic and strong cation-exchange interaction. The resulting immobilized CRL increased remarkably its stability at high temperature in comparison to free CRL. The immobilized CRL was used as biocatalysts for enzymatic esterification of phytosterols with free fatty acids (FFAs) to produce phytosterol esters. The phytosterols linolenate esterification degree of 95.3% was obtained under the optimized condition. Phytosterols esters could also been converted in high yields to the corresponding long-chain acyl esters via transesterification with methyl esters of fatty acids (80.5%) or triacylglycerols (above 95.5%) using mixed-mode silica particles immobilized CRL as biocatalyst. Furthermore, the immobilized CRL by absorption retained 78.6% of their initial activity after 7 recycles.

In-tube solid-phase microextraction based on hybrid silica monolith coupled to liquid chromatography-mass spectrometry for automated analysis of ten antidepressants in human urine and plasma.

A rapid, sensitive and automated in-tube solid-phase microextraction-liquid chromatography-mass spectrometry (in-tube SPME/LC-MS) method was developed for the analysis of ten antidepressants in urine and plasma. A hybrid organic-inorganic silica monolith with cyanoethyl functional groups was prepared and used as a sorbent for in-tube SPME. Integration of the sample extraction, LC separation and MS detection into a single system permitted direct injection of the diluted urine or plasma after filtration. Under the optimized conditions, good extraction efficiencies for the targets were obtained with no matrix interference in the subsequent LC-MS. Automation of the sampling, extraction and separation procedures was realized under the control of a program in this study. The total process time was 30 min and only 30 µL of urine or plasma was required in one analysis cycle. Good linearities were obtained for ten antidepressants with the correlation coefficients (R) above 0.9933. The limits of detection (S/N=3) for ten antidepressants were found to be 0.06-2.84 ng/mL in urine and 0.07-2.95 ng/mL in plasma. The recoveries of antidepressants spiked in urine and plasma were from 75.2% to 113.0%, with relative standard deviations less than 16.5%. The developed method was successfully used to analyze urine sample from ageing patients undergoing therapy with antidepressants.

Comparison of second-trimester maternal serum free-beta-human chorionic gonadotropin and alpha-fetoprotein between normal singleton and twin pregnancies: a population-based study.

BACKGROUND: The second-trimester maternal serum screening in twin pregnancy is still controversial, as the serum marker levels in twins are not as clear as those in singletons. This study aimed to evaluate the relationship between the levels of the second-trimester maternal serum free beta-human chorionic gonadotropin (free beta-HCG) and alpha-fetoprotein (AFP) in normal twin and singleton pregnancies and to estimate feasible analysis methods for utilizing these markers in second trimester screening for twin pregnancy. METHODS: On the basis of a prospective population-based study of second-trimester maternal serum screening, the concentrations of maternal serum AFP and free beta-HCG of 195 normal twin pregnancy and 26,512 singleton controls at gestational weeks 15 to 20 were measured by time-resolved fluoroimmunoassay in one laboratory. The levels of markers were compared between the twins and singletons using weight-correction and gestational age-specific model. RESULTS: According to the research protocol, 95 communities were randomly sampled, which covered the whole Jiangsu province, the east of China. A total of 26 803 pregnant women (98%), from the target population accepted prenatal screening for maternal serum AFP, beta-HCG detection, and all babies were followed up for at least six months. There were 197 (0.73%) twin pregnancies, of which one case had fetal trisomy 18, and one case with fetal anencephaly. The others were normal twin pregnancy. From a total enrollment of 26 803 women participants, 26 512 women with normal singleton pregnancies were selected as the model controls. The other 291 pregnancies, including trisomy 21, neural tube defect (NTD), trisomy 18, and other fetal abnormalities, were excluded. No significant differences were found in the medians of gestational age-specific maternal serum free beta-hCG and AFP in normal twin pregnancy comparing with twice those in model controls with the exception of the medians for free beta-hCG during the 16th gestational week (P = 0.012). CONCLUSION: The weight-correction and gestational age-specific levels of Chinese Han population maternal serum free beta-hCG and AFP in normal twins were twice the levels as those in the singleton controls during the 17-19 gestational weeks.

Preparation of organic-inorganic hybrid silica monolith with octyl and sulfonic acid groups for capillary electrochromatograhpy and application in determination of theophylline and caffeine in beverage.

An organic-inorganic hybrid silica monolithic column with octyl and sulfonic acid groups has been prepared by sol-gel technique for capillary electrochromatograhpy. The structure of hybrid monolith was optimized by changing the composition of tetraethoxysilane (TEOS), octyltriethoxysilane (C(8)-TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) in the mixture of precursors. Then, the obtained hybrid monolith was oxidized using hydrogen peroxide (30%, w/w) to yield sulfonic acid groups. The sulfonic acid group, which served as strong cation-exchanger, dominated the charge on the surface of the capillary column and generated stable electroosmotic flow (EOF) in a wide range of pH. The monolithic column was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and elemental analysis (EA), and the performance of column was evaluated in detail by separating different kinds of compounds with column efficiency up to 155,000 plates/m for thiourea. In addition, this monolithic column was also applied in the analysis of theophylline (TP) and caffeine (CA) in beverages. The detection limits were 0.39 and 0.48 microg/mL for theophylline and caffeine, respectively. The method reproducibility was tested by evaluating the intra- and inter-day precisions, and relative standard deviations of less than 3.9 and 8.4%, respectively, were obtained. Recoveries of compounds from spiked beverage samples ranged from 87.2 to 105.2%.

Selective sample pretreatment by molecularly imprinted polymer monolith for the analysis of fluoroquinolones from milk samples.

Water-compatible pefloxacin-imprinted monoliths synthesized in a water-containing system were used for the selective extraction of fluoroquinolones (FQs). The MIP monolith was synthesized by using methacrylic acid as the functional monomer, di(ethylene glycol) dimethacrylate as a cross-linker and methanol-water (10:3, v/v) as the porogenic solvent. The ability of the derivated MIP for selective recognition of FQs (ciprofloxacin, difloxacin, danofloxacin and enrofloxacin) and quinolones (flumequine, and oxolinic acid) was evaluated. The derivated monolith showed high selectivity and was able to distinguish between FQs and quinolones. A simple rapid and sensitive method using polymer monolith microextraction (PMME) based on the MIP monolith combined with HPLC with fluorescence detection was developed for the determination of four FQs from milk samples. Owing to the unique porous structure and flow-through channels in the network skeleton of the MIP monolith, phosphate buffer diluted milk samples were directly supplied to PMME; allowing non-specific bound proteins and other biological matrix to be washed out, and FQs to be selectively enriched. The limit of detection of the method was 0.4-1.6ng/mL and recovery was 92.4-98.2% with relative standard deviations less than 5.9%.

Combining poly (methacrylic acid-co-ethylene glycol dimethacrylate) monolith microextraction and octadecyl phosphonic acid-modified zirconia-coated CEC with field-enhanced sample injection for analysis of antidepressants in human plasma and urine.

A method based on poly (methacrylic acid-co-ethylene glycol dimethacrylate) monolith microextraction and octadecylphosphonic acid-modified zirconia-coated CEC followed by field-enhanced sample injection preconcentration technique was proposed for sensitive CE-UV analysis of six antidepressants (doxepin, clozapine, imipramine, paroxetine, fluoxetine and chlorimipramine) in human plasma and urine. A poly(methacrylic acid-co-ethylene glycol dimethacrylate) monolithic capillary column was introduced for the extraction of antidepressants from urine and plasma samples. The hydrophobic main chains and acidic pendant groups of the monolithic column make it a superior material for extraction of basic analytes from aqueous matrix. After extraction, the desorption solvent, which normally provided an excellent medium to ensure direct compatibility for field-enhanced sample injection in CE, was analyzed by CE directly. By the use of alkylphosphonate-modified zirconia-coated CEC for separation of the basic compounds of antidepressants, high separation efficiency and resolution were achieved because that both hydrophobic interaction between analytes and alkylphosphonate-modified zirconia coat and electrophoretic effect work on the separation of antidepressants. The best separation was achieved using a buffer composed of 0.3 M ammonium acetate (adjusted to pH 4.5 with 1 M acetic acid) and 35% ACN v/v, with a temperature and voltage of 20 degrees C and 20 kV, respectively. By applying both preconcentration procedures, LODs of 11.4-51.5 and 3.7-17.0 microg/L were achieved for the six antidepressants in human plasma and urine, respectively. Excellent method of reproducibility was found over a linear range of 50-5000 microg/L in plasma and urine sample.