A Visible‐Light‐Regulated Chloride Transport Channel Inspired by Rhodopsin

Abstract

Inspired by the light‐regulating capabilities of naturally occurring rhodopsin, we have constructed a visible‐light‐regulated Cl−‐transport membrane channel based on a supramolecular host–guest interaction. A natural retinal chromophore, capable of a visible‐light response, is used as the guest and grafted into the artificial channel. Upon introduction of an ethyl‐urea‐derived pillar[6]arene (Urea‐P6) host, threading or de‐threading of the retinal and selective bonding of Cl− can be utilized to regulate ion transport. Based on the visible‐light responsiveness of the host–guest interaction, Cl− transport can be regulated by visible light between ON and OFF states. Visible‐light‐regulated Cl− transport as a chemical model permits to understand comparable biological ion‐selective transport behaviors. Furthermore, this result also supplies a smart visible‐light‐responsive Cl− transporter, which may have applications in natural photoelectric conversion and photo‐controlled delivery systems.

Chiral Nanochannels of Ordered Mesoporous Silica Constructed by a Pillar[5]arene-Based Host–Guest System

“…In order to further illuminate selective adsorption in the nanochannel of the LAP5@SBA-15 membrane, the ratio ( R = [ I – I 0 ]/ I 0 ) was calculated, where I 0 and I are the current at +2 V before and after adding with propranolol enantiomers. The ratio increased below 5 × 10 –4 M and formed a platform at a higher concentration; the trend was similar to the Langmuir absorption isotherm. , As reported in previous literature, a Langmuir linear fit equation is as follows: C / R = 1/ KR max + C / R max . R -PPL had a bigger K value in the nanochannel (Figure a), which illustrates the LAP5@SBA-15 hybrid membrane exhibiting a higher binding affinity for R -PPL entering its nanochannel.…”

“…The ratio increased below 5 × 10 −4 M and formed a platform at a higher concentration; the trend was similar to the Langmuir absorption isotherm. 44,45 As reported in previous literature, a Langmuir linear fit equation is as follows: C/R = 1/KR max + C/ R max . R-PPL had a bigger K value in the nanochannel (Figure 6a), which illustrates the LAP5@SBA-15 hybrid membrane exhibiting a higher binding affinity for R-PPL entering its nanochannel.…”

Rational ion transport management mediated through membrane structures

“…Specific ions can then be conducted or intercepted periodically by nanochannels. [ 27,28,74 ] For instance, a series of single (e.g., pH, [ 75 ] light, [ 76,77 ] electricity, [ 78 ] and magnetism [ 79 ] ) and double (e.g., ion and pH, [ 80 ] light and pH, [ 81 ] and electricity and pH [ 82 ] ) stimulus‐responsive gatings were obtained after decorating stimulus‐responsive molecules on the nanochannel walls. The ionic conductance of these membranes can be directly used to illustrate the closing and opening states of ion gating.…”

Tailoring CO2-Activated Ion Nanochannels Using Macrocyclic Pillararenes

“…In addition, taking advantage of the high selectivity and reversibility of host–guest systems, Li and co-workers proposed decorating the internal walls of nanochannels with host–guest systems for the construction of artificial ion gates . Recently, they described the visible-light-regulated chloride transport by introducing the ethyl-urea-derived pillararene into the nanochannel . Compared to other external-stimuli-responsive nanochannelssuch as those sensitive to light, − temperature, − and chirality , examples of gas-responsive nanochannels, − particularly CO 2 -responsive, are still rare.…”

“…49 Recently, they described the visible-lightregulated chloride transport by introducing the ethyl-ureaderived pillararene into the nanochannel. 50 Compared to other external-stimuli-responsive nanochannelssuch as those sensitive to light, 51−59 temperature, 60−63 and chirality 64,65  examples of gas-responsive nanochannels, 66−68 particularly CO 2 -responsive, are still rare. These results inspired us to design a macrocyclic receptor with CO 2 binding sites to better study CO 2 -activated ion nanochannels.…”