Stimuli-responsive smart gating membranes

Abstract

Membranes are playing paramount roles in the sustainable development of myriad fields such as energy, environmental and resource management, and human health. However, the unalterable pore size and surface properties of traditional porous membranes restrict their efficient applications. The performances of traditional membranes will be weakened upon unavoidable membrane fouling, and they cannot be applied to cases where self-regulated permeability and selectivity are required. Inspired by natural cell membranes with stimuli-responsive channels, artificial stimuli-responsive smart gating membranes are developed by chemically/physically incorporating stimuli-responsive materials as functional gates into traditional porous membranes, to provide advanced functions and enhanced performances for breaking the bottlenecks of traditional membrane technologies. Smart gating membranes, integrating the advantages of traditional porous membrane substrates and smart functional gates, can self-regulate their permeability and selectivity via the flexible adjustment of pore sizes and surface properties based on the "open/close" switch of the smart gates in response to environmental stimuli. This tutorial review summarizes the recent developments in stimuli-responsive smart gating membranes, including the design strategies and the fabrication strategies that are based on the introduction of the stimuli-responsive gates after or during membrane formation, and the positively and negatively responsive gating models of versatile stimuli-responsive smart gating membranes, as well as the advanced applications of smart gating membranes for regulating substance concentration in reactors, controlling the release rate of drugs, separating active molecules based on size or affinity, and the self-cleaning of membrane surfaces. With self-regulated membrane performances, smart gating membranes show great power for use in global sustainable development.

Reversible encapsulation of silver nanoparticles into the helix of amylose (water soluble starch)

“…Thus we may state condently that the encapsulation and/or release of AgNPs might be due to the helical shape of amylose. 51 Our results (starch-capped encapsulated AgNPs) could deliver nanoparticles in the human body to cure the infections and diseases. Amylose (water soluble) can easily be detached from the surface of AgNPs which could be used as a drug release vehicle for biomedical and other pharmaceutical applications in the future.…”

“…48 It has been established that the functional gates in membrane pores (linear polymer chains, cross linked hydrogel networks, and microspheres) were responsible for drug delivery. [49][50][51] Dioscorea deltoidea has also been used as a raw material for the synthesis of steroidal drugs. Thus we may state condently that the encapsulation and/or release of AgNPs might be due to the helical shape of amylose.…”

Artificial Perspiration Membrane by Programmed Deformation of Thermoresponsive Hydrogels

“…In principle, the energy density of perspiration is about 2 MJ kg −1 (latent heat of water), [12] which is high enough considering the cooling efficiency of traditional coolers and the energy density of batteries (≈2 MJ kg −1 in the case of lithiumion batteries). [14][15][16][17][18] However, it is still challenging to use them for cooling, because the pore size of the hydrogels needs to be regulated at the water-air interface where evaporation happens. The maximum evaporation rate is determined by environment condition such as humidity so cannot be controlled by the device.…”

Microfabricated Drug Delivery Devices: Design, Fabrication, and Applications

“…[78][79][80][81] They could be fabricated into different functional components for a device such as valves, [82][83][84] gating membranes, [51,85] channels, and hinges [86,87] or serve as drug depots, [79,88] which can trigger and stop drug flux in response to environmental stimuli like pH, temperature, biological molecules, light, electromagnetic fields. [78][79][80][81] They could be fabricated into different functional components for a device such as valves, [82][83][84] gating membranes, [51,85] channels, and hinges [86,87] or serve as drug depots, [79,88] which can trigger and stop drug flux in response to environmental stimuli like pH, temperature, biological molecules, light, electromagnetic fields.…”