Etching and Doping of Pores in Polyethylene Terephthalate Analyzed by Ion Transmission Spectroscopy and Nuclear Depth Profiling

This work is devoted to the study of controlled preparation and filling of pores in polyethylene terephthalate (PET) membranes. A standard wet chemical etching with different protocols (isothermal and isochronous etching for different times and temperatures and etching from one or both sides of the films) was used to prepare the micrometric pores. The pores were filled with either a LiCl solution or boron deposited by magnetron sputtering. Subsequent control of the pore shape and dopant filling was performed using the nuclear methods of ion transmission spectroscopy (ITS) and neutron depth profiling (NDP). It turned out that wet chemical etching, monitored and quantified by ITS, was shown to enable the preparation of the desired simple pore geometry. Furthermore, the effect of dopant filling on the pore shape could be well observed and analyzed by ITS and, for relevant light elements, by NDP, which can determine their depth (and spatial) distribution. In addition, both non-destructive methods were proven to be suitable and effective tools for studying the preparation and filling of pores in thin films. Thus, they can be considered promising for research into nanostructure technologies of thin porous membranes.

Polymer Membranes with Vertically Oriented Pores Constructed by 2D Freezing at Ambient Temperature

Polymer membranes with well-controlled and vertically oriented pores are of great importance in the applications for water treatment and tissue engineering. On the basis of two-dimensional solvent freezing, we report environmentally friendly facile fabrication of such membranes from a broad spectrum of polymer resources including poly(vinylidene fluoride), poly(l-lactic acid), polyacrylonitrile, polystyrene, polysulfone and polypropylene. Dimethyl sulfone, diphenyl sulfone, and arachidic acid are selected as green solvents crystallized in the polymer matrices under two-dimensional temperature gradients induced by water at ambient temperature. Parallel Monte Carlo simulations of the lattice polymers demonstrate that the directional process is feasible for each polymer holding suitable interaction with a corresponding solvent. As a typical example of this approach, poly(vinylidene fluoride) membranes exhibit excellent tensile strength, high optical transparence, and outstanding separation performance for the mixtures of yeasts and lactobacilli.

Fabrication of a mercaptoacetic acid pillar[5]arene assembled nanochannel: a biomimetic gate for mercury poisoning

Mercury ion binding blocks potassium ion channels, which leads to toxicity in vivo. It is challenging to design a simple and efficient artificial system to mimic the sophisticated biological process of mercury poisoning. Herein, based on biomimetic strategies, a tunable mercury(ii) ion-gate modulated by mercaptoacetic acid-pillar[5]arene (MAP5) is reported. By virtue of the unique design of the host-guest competition, potassium ion transport can actualize the reversible switching between "on" and "off" in the absence and presence of mercury ions. Moreover, the MAP5-immobilized nanochannel is highly effective at distinguishing Hg²⁺ from other metal ions and can be used to detect Hg²⁺ and act as an excellent and robust gate valve for developing integrated circuits and nanoelectronic logic devices. This study paves a new way for better understanding the physiological phenomenon of mercury toxicity and shows great promise for biomedical research.

PEI/Zr⁴⁺-coated nanopore for selective and sensitive detection of ATP in combination with single-walled carbon nanotubes

By virtue of a biomimetic nanopore and single-walled carbon nanotubes, a new sensor for adenosine triphosphate (ATP) detection is designed. As compared to the routine approach, the present scenario does not entail the surface modification of nanopore with analyte-specific probes. The underlying mechanism relies on a symmetric nanopore sequentially modified with polyethyleneimine (PEI) and Zr(4+) that can quantitate the concentration of ATP-bound aptamer, while other free aptamers are removed by single-walled carbon nanotubes (SWNTs). The detection limit of the nanopore sensor is 27.46 nM, and the linear range is from 50 nM to 400 nM. The biosensor with an excellent selectivity against guanosine triphosphate (GTP), uridine triphosphate (UTP), and cytosine triphosphate (CTP) can be applied in the real samples such as Hela cell.