Modulating the performance of lipase-hydrogel microspheres in a "micro water environment".

In our previous work, we successfully stimulated lipase activity in an anhydrous reaction system using porous polyacrylamide hydrogel microsphere (PPAHM) as a carrier of lipase and free water. However, the effect of the existence state and content of water in lipase-porous polyacrylamide hydrogel microsphere (L-PPAHM) on the interfacial activation remained unclear. In this work, L-PPAHM with different water contents were obtained by water mist rehydration and were used to catalyze the synthesis of conjugated linoleic acid ethyl ester (CLA-EE). The results revealed that there were three existence states of water in L-PPAHM: bound water, semi-bound water and free water, and free water provided the "micro water environment" for the interfacial activation of lipase. The reusability of L-PPAHM with different water contents showed that the activity and stability of L-PPAHM could be achieved by varying the water content of L-PPAHM. The proportion of free water in L-PPAHM increased, and the activity of L-PPAHM increased, but the strength of hydrogen bond interaction between PPAHM and lipase weakened, resulting in the decrease of stability. L-PPAHM with 2/3 of water absorption could ensure sufficient immobilized lipase activity and stability, and its water absorption property could reduce the free water generated during esterification, thus increasing the yield of CLA-EE.

Hydrogen-bonded lipase-hydrogel microspheres for esterification application.

Lipase is the most widely used enzyme in industry. Due to its unique "lid" structure, lipase can only show high activity at the oil-water interface, which means that water is needed in the catalytic esterification process. However, the traditional lipase catalytic system cannot effectively control "micro-water" in the esterification environment, resulting in the high content of free water, which hinders the esterification reaction and reduces the yield. In this paper, a promising strategy of esterification catalyzed by polyacrylamide hydrogel immobilized lipase is reported. The porous polyacrylamide hydrogel microspheres (PHM) prepared by inverse emulsion polymerization are used as carrier to adsorb lipase by hydrogen bonding interaction. These hydrogel microspheres provide a "micro-water environment" for lipase in the anhydrous reaction system, and further provide an oil-water interface for "interface activation" of lipase. The obtained lipase-porous polyacrylamide hydrogel microspheres (L-PHMs) exhibit higher temperature and pH stability compared with free lipase, and the optimum enzymatic activity reach 1350 U/g (pH 6, 40 °C). L-PHMs can still remain about 49% of their original activity after 20 reuses. Furthermore, L-PHMs have been successfully applied to catalyze the synthesis of conjugated linoleic acid ethyl ester. The results suggest that this immobilization method opens up a new way for the application of lipase in ester synthesis.

A lipase/poly (ionic liquid)-styrene microspheres/PVA composite hydrogel for esterification application.

Enzymes are particularly attractive as biocatalysts for the green synthesis of chemicals and pharmaceuticals. However, the traditional enzyme purification and separation process is complex and inefficient, which limits the wide application of enzyme catalysis. In this paper, an efficient strategy for enzyme purification and immobilization in one step is proposed. A novel poly (ionic liquid)-styrene microsphere is prepared by molecular design and synthesis for adsorbing and purifying high activity lipase from fermentation broth directly. By optimizing the surface morphologies and charge of the microspheres, the enzyme loading is significantly improved. In order to further stabilize the catalytic environment of lipase, the resulting lipase/poly (ionic liquid)-styrene microspheres are immobilized in physical crosslinking hydrogel to obtain a complex lipase catalytic system, which can be prepared into various shapes according to the requirements of catalytic environment. In the actual catalytic reaction process, this complex lipase catalytic system exhibits excellent catalytic activity (6314.69 ± 21.27 U mg-1) and good harsh environment tolerance compared with the lipase fermentation broth (1672.87 ± 36.68 U mg-1). Under the condition of cyclic catalysis, the complex lipase catalytic system shows the outstanding reusability (After 8 cycles the enzymatic activity is still higher than that of the lipase fermentation broth) and is easily separated from the products.

New horizons in the roles and associations of COX-2 and novel natural inhibitors in cardiovascular diseases.

Age-related cardiovascular disease is the leading cause of death in elderly populations. Coxibs, including celecoxib, valdecoxib, etoricoxib, parecoxib, lumiracoxib, and rofecoxib, are selective cyclooxygenase-2 (COX-2) inhibitors used to treat osteoarthritis and rheumatoid arthritis. However, many coxibs have been discontinued due to adverse cardiovascular events. COX-2 contains cyclooxygenase (COX) and peroxidase (POX) sites. COX-2 inhibitors block COX activity without affecting POX activity. Recently, quercetin-like flavonoid compounds with OH groups in their B-rings have been found to serve as activators of COX-2 by binding the POX site. Galangin-like flavonol compounds serve as inhibitors of COX-2. Interestingly, nabumetone, flurbiprofen axetil, piketoprofen-amide, and nepafenac are ester prodrugs that inhibit COX-2. The combination of galangin-like flavonol compounds with these prodrug metabolites may lead to the development of novel COX-2 inhibitors. This review focuses on the most compelling evidence regarding the role and mechanism of COX-2 in cardiovascular diseases and demonstrates that quercetin-like compounds exert potential cardioprotective effects by serving as cofactors of COX-2.

[Analysis of Correlation between TTF-1 and Sensitivity to First-line Chemotherapy and Prognosis in Patients with Small Cell Lung Cancer].

BACKGROUND: Thyroid transcription factor-1 (TTF-1) has been widely studied in non-small cell lung cancer, which is considered as an independent prognostic factor in patiens with non-small cell lung cancer. However, there are few studies on the prognostic value of TTF-1 in small cell lung cancer (SCLC). The purpose of this study was to explore the relationship between the expression state of TTF-1 and the sensitivity to first-line chemotherapy and prognosis in patients with SCLC. METHODS: A retrospective analysis was made on 234 patients with SCLC who were diagnosed and treated in The Affiliated Hospital of Qingdao University and received platinum-based chemotherapy. The clinical characteristics, treatment and survival of the patients were followed up. Chi χ² test and Logistic regression model were used to analyze the relationship between TTF-1 expression and chemotherapy response rate. Kaplan-Meier method and Cox proportional hazard regression model were used to analyze the effect of TTF-1 expression on survival time of patients. RESULTS: Among the 234 patients, the positive expression of TTF-1 was 188 cases (80.3%), and the negative expression of TTF-1 was 46 cases (19.7%). The objective response rate (ORR) of first-line chemotherapy in patients with positive expression of TTF-1 was higher than that in patients with negative expression of TTF-1 (70.7% vs 47.8%) (χ²=8.681, P=0.003). Logistic regression multivariate analysis showed that the expression state of TTF-1 was an independent predictor of ORR in first-line chemotherapy (OR=0.216, 95%CI: 0.076-0.615, P=0.004), however this difference was only reflected in LS-SCLC. The median progression free survival (PFS) of patients with negative expression of TTF-1 was shorter than that of patients with positive expression (6.9 months vs 9.0 months) (χ²=9.357, P=0.002). The median OS in TTF-1 negative group was shorter than that in TTF-1 positive group (13.3 months vs 20.1 months)(χ²=12.082, P=0.001). CONCLUSIONS: TTF-1 expression is an independent predictor of first-line chemotherapy response rate and survival in patients with SCLC, and may become a biomarker to predict the efficacy and prognosis of SCLC.

Novel Nonreleasing Antibacterial Hydrogel Dressing by a One-Pot Method.

A novel nonreleasing antibacterial hydrogel dressing with good reusability was prepared by polyethylene glycol dimethacrylate, N,N-methylene-bis-acrylamide, methyl methacrylate, 1-vinyl-3-butylimidazolium, and acrylamide. The ionic liquid of 1-vinyl-3-butylimidazolium was polymerized in the hydrogel to endow the hydrogel dressing with an antibacterial property. The successful synthesis of the hydrogel dressing was proven by FT-IR spectroscopy and energy-dispersive spectrometry. The morphology of the hydrogel was confirmed to be a porous and interconnected network structure by scanning electron microscopy. The resultant hydrogel dressing showed many desirable features, such as a good protein adsorption property and repeatable adhesiveness as well as excellent mechanical properties. Remarkably, the hydrogel dressing displayed broad antibacterial activity against bacteria Staphylococcus aureus and Escherichia coli and fungal Candida albicans. In addition, the hydrogel dressing applied locally on wounded skin of rats could effectively avoid early infection and further accelerate wound healing. The results indicated that the nonreleasing antibacterial hydrogel had potential application in wound dressing.

A novel catalytic material for hydrolyzing cow's milk allergenic proteins: Papain-Cu3(PO4)2·3H2O-magnetic nanoflowers.

Milk allergenic proteins are the main reason of cow's milk allergy. The most common method for removing milk allergenic proteins is enzymatic hydrolysis. However, the direct application of protease to hydrolyze allergens will lead to the introduction of new allergenic proteins. An ideal strategy for removing milk allergenic proteins without introducing new allergenic proteins is immobilization of protease. Herein, we established a simple method to synthesize a novel papain-Cu3(PO4)2·3H2O-magnetic nanoflowers (PCMNs). The PCMNs demonstrated 1556% higher activity than the free alkaline papain. Moreover, the PCMNs could hydrolyze most of allergenic proteins in cow's milk, generating low-sensitive milk. In cycle analysis, the PCMNs also exhibited good reusability and were easily separated from the product.

Combining sequence and Gene Ontology for protein module detection in the Weighted Network.

Studies of protein modules in a Protein-Protein Interaction (PPI) network contribute greatly to the understanding of biological mechanisms. With the development of computing science, computational approaches have played an important role in locating protein modules. In this paper, a new approach combining Gene Ontology and amino acid background frequency is introduced to detect the protein modules in the weighted PPI networks. The proposed approach mainly consists of three parts: the feature extraction, the weighted graph construction and the protein complex detection. Firstly, the topology-sequence information is utilized to present the feature of protein complex. Secondly, six types of the weighed graph are constructed by combining PPI network and Gene Ontology information. Lastly, protein complex algorithm is applied to the weighted graph, which locates the clusters based on three conditions, including density, network diameter and the included angle cosine. Experiments have been conducted on two protein complex benchmark sets for yeast and the results show that the approach is more effective compared to five typical algorithms with the performance of f-measure and precision. The combination of protein interaction network with sequence and gene ontology data is helpful to improve the performance and provide a optional method for protein module detection.