pH and Calcium Cooperative Regulation Nanofluidic Gating Device
In living body, Ca 2+ -responsive ion channels play crucial roles in many biological activities. Inspired by nature, the design and fabrication of artificial smart nanochannels system become a very significant research subject, mimicking the biological Ca 2+ -responsive signals in ion channels. In this article, by using track-etched artificial polyethylene terephthalate (PET) multiporous membrane materials and modifying intelligent molecules O-Phospho-L-tyrosine (OPLT) through chemical
... ion method, we demonstrate a new biomimetic artificial smart responsive ion channel system, which presents the cooperative response to pH and calcium. The nanosystem shows ion selective transport, ion gating and ion rectification property, which is similar to the property of biological Ca 2+ -responsive ion channels. And the cooperative responsive property of pH and calcium in OPLT modified nanochannels was also investigated by measuring the current-voltage (I-V) curves. At a low pH value, the surface charge of the nanochannels walls is positive as a result of the amino group ( 3 NH + ) of OPLT, the nanosystem attracts the anions and inhibits the cations due to electrostatic interactions between the anions passing through the nanochannels and the nanochannels cations walls, resulting in ion current rectification property. Meanwhile, after adding calcium to the nanosystem, no significant changes of ion current are found. The system presents no calcium responsive property. At a high pH value, the surface charge of the nanochannels walls is negative due to the phosphate group ( 2 4 HPO -) of OPLT, the nanosystem shows cations-selective. After adding calcium to the solution, the bonding of phosphate group ( 2 4 HPO -) with calcium (Ca 2+ ) results in the neutralization of the surface charge in the nanochannels. This nanochannels switch the polarity of ion transport from cation-selective to non-selective, and turn from the highly conductive state to the low conductive state. The significant decline of the ion current can be observed. Thus, the OPLT modified nanofluidic gating device displays the cooperative effect of pH and calcium. This system provides a new idea for the multiple signal induced ion gating in conical nanochannel devices.