Integrating Ionic Gate and Rectifier Within One Solid‐State Nanopore via Modification with Dual‐Responsive Copolymer Brushes

Abstract

A dual‐functional nanofluidic device is demonstrated that integrates the ionic gate and the ionic rectifier within one solid‐state nanopore. The functionalities are realized by fabricating temperature‐ and pH‐responsive poly(N‐isopropyl acrylamide‐co‐acrylic acid) brushes onto the wall of a cone‐shaped nanopore. At ca. 25 °C, the nanopore works on a low ion conducting state. When the temperature is raised to ca. 40 °C, the nanopore switches to a high ion conducting state. The closing/opening of the nanopore results from the temperature‐triggered conformational transition of the attached copolymer brushes. Independently, in neutral and basic solutions, the conical nanopore rectifies the ionic current. While in acid solutions, no ion rectifying properties can be found. The charge properties of the copolymer brushes, combined with the asymmetrical pore geometry, render the nanopore a pH‐tunable ionic rectifier. The chemical modification strategy could be applied to incorporate other stimuli‐responsive materials for designing smart multi‐functional nanofluidic systems resembling the “live” creatures in nature.

A biodegradable thermo-responsive hybrid hydrogel: therapeutic applications in preventing the post-operative recurrence of breast cancer

“…N-isopropylacrylamide (NIPAm) is a monomer that can be used to synthesize thermally sensitive polymers. 34 These polymers have been used widely to construct many thermo-sensitive systems, including hydrogels. Therefore, we integrated NIPAm with GNRs to develop a thermo-responsive hydrogel as the carrier for the chemophotothermal co-therapy of local breast cancer recurrence.…”

Bio-inspired smart gating nanochannels based on polymer films

“…For some applications dual/multiple-responsive nanochannels are required that design process is similar to that of single responsive ones, but requires two types of stimuli-responsive materials. According to this strategy, a dual-functional nanofluidic device is demonstrated by us that integrated the ionic gate and the ionic rectifier within one solid-state nanochannel [15]. The functionalities are realized by fabricating temperature-and pH-responsive poly (N-isopropyl acrylamide-co-acrylic acid) brushes onto the wall of a cone-shaped nanochannel (Figure 11(A)).…”

“…The data were measured in 0.1 M KCl, pH 7.2. Reproduced with permission [15]. combined with the asymmetrical pore geometry, render the nanochannel a pH-tunable ionic rectifier (Figure 11(C)).…”

“…In this article, we want to exhibit one particular transport effect that has been observed in a series of specific smart gating nanochannels which were mainly developed by our group [10][11][12][13][14][15][16][17]. Herein, this review is divided into three sections.…”

Bioinspired synthesis of optically and thermally responsive nanoporous membranes

“…[1][2][3] Environmentally responsive porous membranes (ERPMs) have a wide array of applications, including use in sensors, bioseparation, drug delivery systems and valves that serve to interconnect microfluidic systems and control interflow. [3][4][5][6][7][8][9][10][11][12] For decades, the efforts to develop ERPMs have been approached mainly through the coupling of environmentally responsive polymers to polymeric porous membranes. This technique allows for rapid 'on/ off' switching and flow control because it synergizes the chemical stability and mechanical strength of the polymer membrane with the fast response times of the free-ended polymer chains chemically bonded to them.…”