Glutathione transmembrane transmission gated by light-switches

Chiral Drug Resolution Nanochannels Inspired by Mitochondrial Membranes

Fungicides have been widely used in agricultural production; however, their extensive use has caused serious environmental pollution. Because of its high efficiency, low toxicity, and high selectivity, chiral fungicides can effectively reduce the amount of fungicides and increase the efficiency. Hence, how to efficiently separate the enantiomers of chiral drugs with different structures is of significant research value. The multispecific recognition and selective control of the mitochondrial membrane during the transfer of substances allow us to isolate and enrich monochiral pesticide enantiomers. In this study, based on the conical nanochannel modification by L-alanine pillar[5]arene, combined with the "synergistic effect of double-layer membrane channel" of the mitochondrial membrane in living organisms, three different modes of double-layer serial biomimetic nanochannels were constructed. At the same time, the effect of three different modes of the tandem double nanochannel on hand selectivity is investigated. The results demonstrate that the SOD-In double nanochannels exhibit the optimal separation performance. In the experiment, using current as the detection signal, the selectivity ratio of R-propranolol/S-propranolol was determined to be 43.67. The transmembrane transport selectivity coefficient α(R-/S-PPL) was 13.19 in the single molecule transmission experiment. This study provides an effective method for highly selective enrichment of single configuration chiral pesticides, promoting green agriculture development.

Gadolinium-Sensitive Artificial Nanochannel Membrane for Information Encryption

Inspired from ion channels in the myelinated axon of Xenopus laevis found to be affected by gadolinium on axonal currents, we present a solid nanochannel membrane sensitive to gadolinium (Gd3+), which can be achieved via the use of the macrocyclic triacetic acid derivative in the host-guest chemistry approach. The macrocyclic nanochannel has good responsiveness toward Gd3+, even at the nanomolar concentration level, evidenced by discernible changes in rectification, ionic conductance, and XPS analyses. Notably, the Gd3+-sensitive nanochannel membrane can be switched by the addition of a diethylenetriaminepentaacetic acid (DTPA) derivative. Further studies have indicated that the gated behavior of Gd3+ in the nanochannel can be attributed to the strong binding strength between DO3A and Gd3+, which induces a surface charge reversal within the nanochannel. The mechanism has been confirmed through several experimental techniques, including isothermal titration calorimetry (ITC) experiments, fluorescence titration experiments, and finite element analysis. Based on its Gd3+ responsiveness of the constructed ion channel, we successfully developed an advanced multilevel information encryption application of the artificial solid nanochannel membrane. Furthermore, it is anticipated that a more effective encryption system will be built by utilizing the bionic ion channel system's ease of use and straightforward functionalization.

Visible Light-Gating Responsive Nanochannel for Controlled Release of the Fungicide

Fungicides have been widely used to protect crops from the disease of pythium aphanidermatum (PA). However, excessive use of synthetic fungicides can lead to fungal pathogens developing microbicide resistance. Recently, biomimetic nano-delivery systems have been used for controlled release, reducing the overuse of fungicides, and thereby protecting the environment. In this paper, inspired by chloroplast membranes, visible light biomimetic channels are constructed by using retinal, the main component of green pigment on chloroplasts in plants, which can achieve the precise controlled release of the model fungicide methylene blue (MB). The experimental results show that the biomimetic channels have good circularity after and before light conditions. In addition, it is also found that the release of MB in visible light by the retinal-modified channels is 8.78 µmol·m-2·h-1, which is four times higher than that in the before light conditions. Furthermore, MB, a bactericide drug model released under visible light, can effectively inhibit the growth of PA, reaching a 97% inhibition effect. The biomimetic nanochannels can realize the controlled release of the fungicide MB, which provides a new way for the treatment of PA on the leaves surface of cucumber, further expanding the application field of biomimetic nanomembrane carrier materials.

Engineering solid nanochannels with macrocyclic host-guest chemistry for stimuli responses and molecular separations

Biological channels in the cell membrane play a critical role in the regulation of signal transduction and transmembrane transport. Researchers have been committed to building biomimetic nanochannels to imitate the above significant biological processes. Unlike the fragile feature of biological channels, numerous solid nanochannels have aroused extensive interests for their controllable chemical properties on the surface and superior mechanical properties. Surface functionalization has been confirmed to be vital to determine the properties of solid nanochannels. Macrocyclic hosts (e.g., the crown ethers, cyclodextrins, calix[n]arenes, cucurbit[n]urils, pillar[n]arenes, and trianglamine) can be tailored to the interior surface of the nanochannels with the performance of stimuli response and separation. Macrocycles have good reversibility and high selectivity toward specific ions or molecules, promoting functionalies of solid nanochannels. Hence, the combination of macrocyclic hosts and solid nanochannels is conducive to taking both advantages and achieving applications in functional nanochannels (e.g., membranes separations, biosensors, and smart devices). In this review, the most recent advances in nanochannel membranes decorated by macrocyclic host-guest chemistry are briefed. A variety of macrocyclic hosts-based responsive nanochannels are organized (e.g., the physical stimuli and specific molecules or ions stimuli) and nanochannels are separated (e.g., water purifications, enantimerseparations, and organic solvent nanofiltration), respectively. Hopefully, this review can enlighten on how to effectively build functional nanochannels and facilitate their practical applications in membrane separations.

Light-responsive nanochannels based on the supramolecular host–guest system

The light-responsive nanochannel of rhodopsin gained wider research interest from its crucial roles in light-induced biological functions, such as visual signal transduction and energy conversion, though its poor stability and susceptibility to inactivation in vitro have limited its exploration. However, the fabrication of artificial nanochannels with the properties of physical stability, controllable structure, and easy functional modification becomes a biomimetic system to study the stimulus-responsive gating properties. Typically, light-responsive molecules of azobenzene (Azo), retinal, and spiropyran were introduced into nanochannels as photo-switches, which can change the inner surface wettability of nanochannels under the influence of light; this ultimately results in the photoresponsive nature of biomimetic nanochannels. Furthermore, the fine-tuning of their stimulus-responsive properties can be achieved through the introduction of host–guest systems generally combined with a non-covalent bond, and the assembling process is reversible. These host–guest systems have been introduced into the nanochannels to form different functions. Based on the host–guest system of light-responsive reversible interaction, it can not only change the internal surface properties of the nanochannel and control the recognition and transmission behaviors but also realize the controlled release of a specific host or guest molecules in the nanochannel. At present, macrocyclic host molecules have been introduced into nanochannels including pillararenes, cyclodextrin (CD), and metal–organic frameworks (MOFs). They are introduced into the nanochannel through chemical modification or host–guest assemble methods. Based on the changes in the light-responsive structure of azobenzene, spiropyran, retinal, and others with macrocycle host molecules, the surface charge and hydrophilic and hydrophobic properties of the nanochannel were changed to regulate the ionic and molecular transport. In this study, the development of photoresponsive host and guest-assembled nanochannel systems from design to application is reviewed, and the research prospects and problems of this photo-responsive nanochannel membrane are presented.

Photoresponsive Solid Nanochannels Membranes: Design and Applications

Light stimuli have notable advantages over other environmental stimuli, such as more precise spatial and temporal regulation, and the ability to serve as an energy source to power the system. In nature, photoresponsive nanochannels are important components of organisms, with examples including the rhodopsin channels in optic nerve cells and photoresponsive protein channels in the photosynthesis system of plants. Inspired by biological channels, scientists have constructed various photoresponsive, smart solid-state nanochannels membranes for a range of applications. In this review, the methods and applications of photosensitive nanochannels membranes are summarized. The authors believe that this review will inspire researchers to further develop multifunctional artificial nanochannels for applications in the fields of biosensors, stimuli-responsive smart devices, and nanofluidic devices, among others.

Efficient Chiral Nanosenor Based on Tip-Modified Nanochannels

Enantiomers of various drug molecules have a specific effect on living organisms. Accordingly, developing a sample method for the efficient and rapid recognition of chiral drug enantiomers is of great industrial value and physiological significance. Here, inspired by the structure of ion channels in living organisms, we developed a chiral nanosensor based on an artificial tip-modified nanochannel system that allows efficient selective recognition of chiral drugs. In this system, l-alanine-pillar[5]arenes as selective receptors were introduced on the tip side of conical nanochannels to form an enantioselective "gate". The selective coefficient of our system toward R-propranolol is 4.96, which is higher than the traditional fully modified nanochannels in this work.