Functionalized silica nanoparticles coupled with nanoporous membrane for efficient ionic current rectification.

In the last few decades, tremendous effort has been dedicated to mimicking the efficient ionic current rectification (ICR) of biological nanopores. Nanoporous membranes and singular nanopores with ICR functionality have been fabricated using advanced, yet costly technologies. We herein demonstrate that a simple, novel, and robust ICR platform can be constructed using 80 nm silica nanoparticles and a piece of 15 nm track-etched polycarbonate membrane. Efficient ICR can be obtained when voltages of different polarities are applied across the membrane, due to the asymmetric electrophoretic migration of silica nanoparticles whose surfaces are modified with different functional groups. The effect of pore size, ionic strength, pH, voltage magnitude, and density of silica nanoparticles on the efficiency of the ICR system has been systematically investigated in this report. Our results clearly show that smaller pore, lower ionic strength, appropriate pH value, higher electrical field strength, lower density of silica nanoparticles can generally enhance the efficiency of the ICR system. The principles of this new ICR system may find many potential applications in controllable drug delivery, energy storage and water purification.

Inkjet Printing of Nanoscale Functional Patterns on 2D Crystalline Materials and Transfer to Soft Materials.

Nanometer-scale control over surface functionality is important in applications ranging from nanoscale electronics to regenerative medicine. However, approaches that provide precise control over surface chemistry at the nanometer scale are often challenging to use with higher throughput and in more heterogeneous environments (e.g., complex solutions, porous interfaces) common for many applications. Here, we demonstrate a scalable inkjet-based method to generate 1 nm-wide functional patterns on 2D materials such as graphite, which can then be transferred to soft materials such as hydrogels. We examine fluid dynamics associated with the inkjet printing process for low-viscosity amphiphile inks designed to maximize ordering with limited residue and show that microscale droplet fluid dynamics influence nanoscale molecular ordering. Additionally, we show that scalable patterns generated in this way can be transferred to hydrogel materials and used to create surface chemical patterns that induce adsorption of charged particles, with effects strong enough to overcome electrostatic repulsion between a charged hydrogel and a like-charged nanoparticle.

Crystal structures and Hirshfeld surface analysis of 5-amino-1-(4-meth-oxy-phen-yl)pyrazole-4-carb-ox-ylic acid and 5-amino-3-(4-meth-oxy-phen-yl)isoxazole.

The title compounds, C11H11N3O3, (I), and C10H10N2O2, (II), are commercially available and were crystallized from ethyl acetate solution. The dihedral angle between the pyrazole and phenyl rings in (I) is 52.34 (7)° and the equivalent angle between the isoxazole and phenyl rings in (II) is 7.30 (13)°. In the crystal of (I), the mol-ecules form carb-oxy-lic acid inversion dimers with an R(8) ring motif via pairwise O-H⋯O hydrogen bonds. In the crystal of (II), the mol-ecules are linked via N-H⋯N hydrogen bonds forming chains propagating along [010] with a C(5) motif. A weak N-H⋯π inter-action also features in the packing of (II). Hirshfeld surface analysis was used to explore the inter-molecular contacts in the crystals of both title compounds: the most important contacts for (I) are H⋯H (41.5%) and O⋯H/H⋯O (22.4%). For (II), the most significant contact percentages are H⋯H (36.1%) followed by C⋯H/H⋯C (31.3%).