Mussel foot protein inspired tough tissue-selective underwater adhesive hydrogel.

Mussel foot proteins (Mfps) show strong adhesion to underwater substrates, making mussels tightly cling to reefs to withstand the sea current. Therefore, Mfps-inspired tissue adhesives have aroused much research interest, but tough underwater biological tissue adhesion is still a great challenge. Herein, we report a tough and reversible wet tissue-selective adhesive hydrogel made of poly(acrylic acid-co-catechol) and chitosan (CS). It provides negatively charged -COO-, positively charged -NH3+, catechol group and hydrophobic alkyl chain, resemble amino acids, catechol and hydrophobic units in Mfps. Due to the covalent/electrostatic attraction/π-π/cationic-π/hydrogen bonding, in addition to the hydrophobic interaction from the long hydrophobic alkyl chain of the catechol derivative, the hydrogel has a high cohesion strength and toughness, i.e., tensile stress, fracture strain and fracture toughness of ∼0.57 MPa, 2510% and 6620 J m-2, respectively. As a tissue adhesive, its adhesion bonding to the porcine skin surface is so strong that its adhesion strength is almost equal to the tearing strength of the hydrogel. The 180-degree peeling adhesion energy of the hydrogel to blood-wetted porcine skin is notably ∼1010 J m-2. It can tightly and seamlessly adhere to the porcine small intestine, and has a bursting pressure of up to 520 mmHg. The hydrogel can be handily debonded from the porcine skin surface in the presence of aqueous solution at pH 8.0, and its adhesiveness is reversible for at least 20 cycles. It is supposed that the synergistic interactions of the adhesive catechol group, displacement of water on the wet skin surface by the positively charged -NH3+ groups of CS and the water-repelling potential of the hydrophobic unit of the catechol derivative, the protection of the catechol group from oxidation into a less adhesive quinone group, and the energy dissipation capacity of the mechanically tough hydrogel contribute to the strong and repeatable wet tissue adhesion.

An Antifreezing/Antiheating Hydrogel Containing Catechol Derivative Urushiol for Strong Wet Adhesion to Various Substrates.

Tough adhesive hydrogels that can tightly bond to wet tissue/polymer/ceramic/metal surfaces have great potentials in various fields. However, conventional adhesive hydrogels usually show short-term and nonreversible adhesion ability, as the water component in a hydrogel readily transforms to vapor or ice in response to fluctuation of environment temperature, hindering their applications in extreme conditions such as in freezing Arctic and roasting Africa. For the first time, urushiol (UH), a natural catechol derivative with a long alkyl side chain, is used as a starting material to copolymerize with acrylamide for fabricating adhesive hydrogels, which contain hydrophobic/hydrophilic moieties, antifreezing agent, and adhesive catechol groups. The antifreezer/moisturizer glycerol/water binary solvent dispersed in the hydrogel endows it with antifreezing/antiheating property. The hydrophobic association and π-π interaction from UH moieties of the copolymer greatly improve its mechanical strength (tensile stress: ∼0.12 MPa with strain of ∼1100%, toughness: ∼72 kJ/m3, compression stress: ∼6.72 MPa at strain of 90%). The hydrogel can strongly adhere to various dry/wet biological/polymeric/ceramic/metallic substrates at temperatures ranging from -45 to 50 °C. Under ambient conditions, its adhesion force to porcine skin, glass, and tinplate may reach up to 160, 425, and 275 N/m, respectively. Even stored at -45 or 50 °C for 30 d, the hydrogel still maintains good flexibility and robust adhesion force. It also shows repeatable underwater adhesion to biological tissue, glass, ceramic, plastic, and rubber. This novel antifreezing/antiheating adhesive hydrogel may be applied in extremely cold or hot environments and in underwater conditions.

One-step recovery of noble metal ions from oil/water emulsions by chitin nanofibrous membrane for further recycling utilization.

A multifunctional membrane, prepared by filtration of partial deacetylated chitin nanofibers, was reported to realize one-step green recovery of noble metal ions from surfactant-stabilized oil/water emulsions. The chitin nanofibrous membrane (CNFM) has nanoporous structure with superhydrophilic and underwater superoleophobic surface and could effectively separate oil/water emulsion. Combining with the chelation ability/reduction of amino groups of chitin, CNFM could simultaneously extract noble metal ions from oily wastewater. Furthermore, the noble metal ions adsorbed on the CNFM could be in situ reduced into metal nanoparticles (NPs) by amino groups on chitin without adding extra reducing agents, to yield NPs-loaded CNFM. Surprisingly, the recovered NPs-loaded CNFM maintained excellent catalytic activities and even displayed peroxidase mimic behavior, showing high potentials in biosensing, green catalysis and related fields. Hence, this work provides a simple and sustainable way to realize directly recovery of noble metal ions from oil/water emulsion.

Role of serum vitamin A and E in pregnancy.

Serum levels of vitamin A and E in early, middle and late pregnancy were analyzed to evaluate vitamin nutritional status in pregnancy, and provide guidance for pregnant women about vitamin supplements in pregnancy. In total, 28,023 serum samples were randomly selected from pregnant women in early, middle and late pregnancy between January 2013 and June 2014 in Beijing. High performance liquid chromatography (HPLC) method was used to determine the concentration of serum vitamin A and E in pregnancy. The concentration of serum vitamin A in early, middle and late pregnancy was 0.33±0.08, 0.37±0.09 and 0.33±0.15 mg/l, respectively, total abnormal rate was 25.31%, and deficiency (24.98%) was the main feature. The rate of deficiency in the early pregnancy (38.22%) was greater than that in late pregnancy (35.13%). The serum vitamin E in early, middle and late pregnancy was 9.10±2.47, 14.24±3.66 and 15.80±5.01 mg/l, respectively, total abnormal rate was 5.60%, and excess (5.37%) was the main feature. The excess rate in early pregnancy was at the lowest level (0.50%), and reached the highest level (15.32%) in late pregnancy. The serum levels of vitamin A and E are different during pregnancy. Generally, vitamin A is deficient and vitamin E is in excess. Therefore, monitoring the vitamin A and E levels, and strengthening perinatal education and providing guidance for pregnant women to supply vitamins rationally play important role in guaranteeing maternal and fetal safety.

Diarylmaleimide-based branched oligomers: strong full-color emission in both solution and solid films.

Maleimide and benzene are employed as a dendron and a core, respectively, to construct two series of non-conjugate branched oligomers (B3G1 and B1G2) based on diarylmaleimide fluorophores by an alkylation reaction. Surface aryl groups are changed to tune the emissive color of branched oligomers from blue (λem = 480 nm) to red (λem = 651 nm), realizing full-color emission. The investigation on the photophysical properties of the oligomers indicates that they display intense emission in both solution and solid films, due to the suppression of intramolecular rotation and intermolecular interaction. Molecular simulation and natural transition orbital analysis show that the electron transition takes place in the individual arylmaleimide for the non-conjugate linkage of fluorophores in branched oligomers. It can avoid the unpredictability of the luminescence properties caused by the interaction of fluorophores. In addition, the good solubility, thermostability and oxidative stability of the branched oligomers make them have huge potential in the solution-processable photonic application. These results demonstrate that such a design strategy of non-conjugate branched oligomers is a very efficient and constructive method to obtain high-performance light-emitting materials in both solution and solid films.

[Screen and identify of differential proteins expressed in the placenta of Down's syndrome].

OBJECTIVE: To discuss protein marks expressed differentially in placenta of Down's syndrome by means of proteomics. METHODS: We collected placenta of 18 patients (from March 2009 to December 2009 at Beijing Obstetrics and Gynecology Hospital), and divided them into two groups, one was 10 patients with fetal Down's syndrome, the other was normal pregnancies (normal chromosome) with other diseases. We separated proteins expressed in placentas of two groups by two-dimensional difference gel electrophoresis (2D-DIGE), and then analyzed the differential protein spots by software Decyder 6.5, then, spots differentially expressed by 1.5 fold or more were analyzed by matrix assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS). In the end, the differential expressional levels of partially identified proteins were validated by western blot analysis. RESULTS: (1) Differential proteins of two groups protein spots of placentas separated by 2D-DIGE were analyzed by software Decyder 6.5 (these colored lights scattered in the image were protein spots), a total of 56 spots out of 352 were differentially expressed (P < 0.05) in two groups. We analyzed 17 protein spots (12 protein spots were over-expressed and 5 protein spots were down-expressed) differentially expressed by 1.5 fold or more by MALDI-TOF-MS. (2) Protein matching after searching protein database, 17 protein spots turn out to be 10 proteins. Four kinds [superoxide dismutase 1 (SOD1), peroxiredoxin 6 (PRDX6), heat shock protein 27 (HSP27), endoplasmic reticulum protein 29 (ERP29)] of them were validated by western blot analysis, the group of fetal Down's syndrome were 0.74 ± 0.12, 0.29 ± 0.10, 0.53 ± 0.16, 0.20 ± 0.09, the group of normal pregnancies were 0.51 ± 0.08, 0.34 ± 0.16, 0.18 ± 0.07, 0.35 ± 0.09, the results confirmed the observed changes in proteomics. CONCLUSIONS: Compared with normal pregnancies, there were differential proteins expressed in placenta of Down's syndrome. This approach might provide new screening markers in use for prediction of Down's syndrome, however, further study should be done to make these 4 proteins (SOD1, HSP27, ERP29, PRDX6) be new screening markers.

Proteomic analysis of the alteration of protein expression in the placenta of Down syndrome.

BACKGROUND: Down syndrome (DS) is the most common form of human aneuploidy, and there is no effective therapy for the chromosomal abnormalities. We aimed to unravel the molecular mechanisms underlying DS and to provide clues to prenatal screening. METHODS: A series of proteomics-based experiments was conducted using 19 patients with DS fetuses and 17 normal pregnancies. The proteome of placenta was investigated as displayed by two-dimensional difference gel electrophoresis (2D-DIGE), and comparisons were made between placentas that developed under DS and normal pregnancy conditions. Multivariate analysis of the resulting protein patterns revealed DS-specific protein expression. Matrix-assisted laser desorption/ionization (MALDI) time-of-flight/time-of-flight (TOF/TOF) high-resolution tandem mass spectrometer (MS)-based identification was successful for 12 out of 17 selected protein spots. RESULTS: Among those, three proteins involved in the resist of reactive oxygen species (ROS) and neurogenesis were more abundant in the DS placenta (superoxide dismutase 1, endoplasmic reticulum protein 29 and heat shock protein beta-1), while peroxiredoxin-6 involved in cell defense mechanism against ROS was expressed at a higher level in the normal pregnancies. CONCLUSION: Knowledge of the DS placenta proteome emphasizes the role of proteins involved in anti-oxidation during DS, and may form the basis of a potential approach to minimize the incidence of DS in the clinical setting.