Towards a High-Flux Separation Layer from Hexagonal Lyotropic Liquid Crystals for Thin-Film Composite Membranes

Hexagonal lyotropic liquid crystals (HLLC) with uniform pore size in the range of 1~5 nm are highly sought after as promising active separation layers of thin-film composite (TFC) membranes, which have been confirmed to be efficient for water purification. The potential interaction between an amphiphile-based HLLC layer and the substrate surface, however, has not been fully explored. In this research, hydrophilic and hydrophobic microporous polyvinylidene fluoride (PVDF) substrates were chosen, respectively, to prepare TFC membranes with the active layers templated from HLLC, consisting of dodecyl trimethylammonium bromide, water, and a mixture of poly (ethylene glycol) diacrylate and 2-hydroxyethyl methacrylate. The pore size of the active layer was found to decrease by about 1.6 Å compared to that of the free-standing HLLC after polymerization, but no significant difference was observable by using either hydrophilic or hydrophobic substrates (26.9 Å vs 27.1 Å). The water flux of the TFC membrane with the hydrophobic substrate, however, was higher than that with the hydrophilic one. A further investigation confirmed that the increase in water flux originated from a much higher porosity was due to the synergistic effect of the hydrophilic HLLC nanoporous material and the hydrophobic substrate.

Light-steered locomotion of muscle-like hydrogel by self-coordinated shape change and friction modulation

Many creatures have the ability to traverse challenging environments by using their active muscles with anisotropic structures as the motors in a highly coordinated fashion. However, most artificial robots require multiple independently activated actuators to achieve similar purposes. Here we report a hydrogel-based, biomimetic soft robot capable of multimodal locomotion fueled and steered by light irradiation. A muscle-like poly(N-isopropylacrylamide) nanocomposite hydrogel is prepared by electrical orientation of nanosheets and subsequent gelation. Patterned anisotropic hydrogels are fabricated by multi-step electrical orientation and photolithographic polymerization, affording programmed deformations. Under light irradiation, the gold-nanoparticle-incorporated hydrogels undergo concurrent fast isochoric deformation and rapid increase in friction against a hydrophobic substrate. Versatile motion gaits including crawling, walking, and turning with controllable directions are realized in the soft robots by dynamic synergy of localized shape-changing and friction manipulation under spatiotemporal light stimuli. The principle and strategy should merit designing of continuum soft robots with biomimetic mechanisms.

Structural basis for active-site probes targeting Staphylococcus aureus serine hydrolase virulence factors

SummaryStaphylococcus aureus is a major cause of infection in the community and in hospitals. Serine hydrolases play key roles in bacterial homeostasis, in particular biofilms. Activity-based profiling has previously identified a family of serine hydrolases, designated fluorophosphonate-binding hydrolases (Fphs), which contribute to virulence of S. aureus in the biofilm niche. Here we report structures of the putative tributyrin esterase FphF, alone and covalently bound by a substrate analog, and small molecule inhibitors that occupy the hydrophobic substrate-binding pocket. We show that FphF has promiscuous esterase activity. Building from this, we extended our analysis to the wider Fph protein family using homology modeling and docking tools. We predict that other Fph enzymes, including FphB which was linked directly to virulence, may be more specific than FphF. This study provides insight into Fph function and a template for designing new imaging agents, diagnostic probes, and inhibitors to treat S. aureus infections.

Non-classical crystal growth on a hydrophobic substrate: learning from bivalve nacre

The hydrophobic substrate has an effect on the non-classical crystallization of nacreous aragonite crystals.

Synergistic effect of a “stellate” mesoporous SiO2@Au nanoprobe and coffee-ring-free hydrophilic–hydrophobic substrate assembly in an ultrasensitive SERS-based immunoassay for a tumor marker

Ultrasensitive SERS-based immunoassay induced by SiO2@Au nanoprobe and hydrophilic–hydrophobic assembly substrate.

Расчет линейного натяжения для простой модели поверхностного нанопузырька

The paper is devoted to the calculation of line tension for a simple model of a surface nano-bubble formed on a smooth hydrophobic substrate. It is shown that with the growth of the contact angle, at a certain critical value, the line tension changes its sign from positive to negative. This means that it begins to stretch the nanobubble, increasing its radius of curvature and thereby contributing to its stabilization