Cryogel with Modular and Clickable Building Blocks: Toward the Ultimate Ideal Macroporous Medium for Bacterial Separation.

The lack of practical platforms for bacterial separation remains a hindrance to the detection of bacteria in complex samples. Herein, a composite cryogel was synthesized by using clickable building blocks and boronic acid for bacterial separation. Macroporous cryogels were synthesized by cryo-gelation polymerization using 2-hydroxyethyl methacrylate and allyl glycidyl ether. The interconnected macroporous architecture enabled high interfering substance tolerance. Nanohybrid nanoparticles were prepared via surface-initiated atom transfer radical polymerization and immobilized onto cryogel by click reaction. Alkyne-tagged boronic acid was conjugated to the composite for specific bacteria binding. The physical and chemical characteristics of the composite cryogel were analyzed systematically. Benefitting from the synergistic, multiple binding sites provided by the silica-assisted polymer, the composite cryogel exhibited excellent affinity toward S. aureus and Salmonella spp. with capacities of 91.6 × 107 CFU/g and 241.3 × 107 CFU/g in 0.01 M PBS (pH 8.0), respectively. Bacterial binding can be tuned by variations in pH and temperature and the addition of monosaccharides. The composite was employed to separate S. aureus and Salmonella spp. from spiked tap water, 40% cow milk, and sea cucumber enzymatic hydrolysate, which resulted in high bacteria separation and demonstrated remarkable potential in bacteria separation from food samples.

Model-Based Dielectric Constant Estimation of Polymeric Nanocomposite.

The interphase region widely exists in polymer-based nanocomposites, which affects the dielectric properties of the nanocomposites. General models, such as the Knott model, are often used to predict the dielectric constant of nanocomposites, while the model does not take the existence of interphase into account, which leads to a large deviation between the predicted results and the experimental values. In this study, a developed Knott model is proposed by introducing the interphase region and appropriately assuming the properties of the interphase. The modeling results based on the developed model are in good agreement with the experimental data, which verifies the high accuracy of the development model. The influence of nanoparticle loading on the effective volume fraction is further studied. In addition, the effects of the polymer matrix, nanoparticles, interphase dielectric and thickness, nanoparticle size and volume fraction on the dielectric properties of the nanocomposites are also investigated. The results show that polymer matrix or nanoparticles with a high dielectric and thick interphase can effectively improve the dielectric properties of the materials. Small size nanoparticles with high concentrations are more conducive to improving the dielectric properties of the nanocomposites. This study demonstrates that the interphase properties have an important impact on the dielectric properties of nanocomposites, and the developed model is helpful to accurately predict the dielectric constant of polymer-based nanocomposites.

Estimating the dielectric constant of BaTiO3-polymer nanocomposites by a developed Paletto model.

Polymer-based nanocomposites with high dielectric constant have attracted the attention of many researchers, owing to their wide applications in advanced electronics. The experimental measurement of dielectric constant for every polymer-based nanocomposite system is not practically feasible, due to there being many polymer matrixes and nanofiller combinations. Therefore, there is rising interest in predicting the dielectric constant of polymer nanocomposites, using mathematical methods. In this study, we estimate the dielectric constant of polymer nanocomposites by considering astounding interphase properties. The Paletto model is modified, in order to predict the dielectric constant of a BaTiO3-polymer nanocomposite by properly assuming the interphase parameters, including the thickness of the interphase layer and the dielectric constant of the interphase region. Results from the modified Paletto model are verified by experimental data, indicating that the predicted values agree well with the experimentally determined dielectric constant, and thus the accuracy of the developed model. In addition, the particle concentration will significantly be underestimated if the influence of the interphase volume is ignored. Furthermore, the effects of different parameters, including the dielectric constant of polymer substrate, dielectric constant of particles, particle content, particle size, the thickness of the interphase layer as well as the dielectric constant of the interphase region on the dielectric constant of a BaTiO3-polymer nanocomposite are also investigated. The developed model provides a useful tool for predicting the dielectric constant of a BaTiO3-polymer nanocomposite, accompanied by interphase analysis.

Improved blood compatibility of polysulfone membrane by anticoagulant protein immobilization.

Two anticoagulant proteins, nattokinase and lumbrokinase, were successfully immobilized onto the dopamine-coated polysulfone (PSf) membrane surface by covalent bonding. X-ray photoelectron spectroscopy (XPS) and Zeta potential measurement confirmed the immobilization of these anticoagulant proteins. The immobilization yield of nattokinase and lumbrokinase reached to 35.2 and 33.4 µg/cm2, respectively. The water contact angle measurement revealed that the membrane surface hydrophilicity was improved after immobilizing the anticoagulant proteins. Meanwhile, the immobilized proteins retained their biological activity. Then blood compatible tests demonstrated that the modified membranes had lower static protein adsorption, platelet/erythrocyte adhesion, hemolysis, as well as longer blood clotting time, compared to virgin PSf membrane. In addition, the nattokinase-immobilized membrane showed a higher blood compatibility than BSA and lumbrokinase immobilized memrbanes, due to its' high bioactivity. Our research demonstrates that the dopamine-assisted immobilization of nattokinase and lumbrokinase can endow the membranes with improved blood compatibility as well as high biological activity, which may be expected to apply to blood-contacting materials.