Water confined in nanoscale space behaves quite differently from that in the bulk.For example,in biological aquaporins and in carbon nanotubes,the traversing water molecules form a single file configuration.Water would stay in vapor state in extremely hydrophobic narrow nanopores owing to the physicochemical interactions between the water molecules and the surface of the nanopore.A spontaneous wet-dry transition has been identified in both biological and artificial nanopores.The nanopore is either fulfilled with liquid water or completely empty.Based on this mechanism,the wetting and dewetting processes inside nanopores have been further developed into highly efficient nanofluidic gates that can be switched by external stimuli,such as light irradiation,electric potential,temperature,and mechanical pressure.This review briefly covers the recent progress in the special wettability in nanoconfined environment,water transportation through biological or artificial nanochannels,as well as the smart nanofluidic gating system controlled by the water wettability.
Self-assembly is the fundamental principle, which can occur spontaneously in nature. Through billions of years of evolution, nature has learned what is optimal. The optimized biological solution provides some inspiration for scientists and engineers. In the past decade, under the multi-disciplinary collaboration, bio-inspired special wetting surfaces have attracted much attention for both fundamental research and practical applications. In this review, we focus on recent research progress in bio-inspired special wetting surfaces via self-assembly, such as low adhesive superhydrophobic surfaces, high adhesive superhydrophobic surfaces, superamphiphobic surfaces, and stimuli-responsive surfaces. The challenges and perspectives of this research field in the future are also briefly addressed.
Poly(N-isopropylacrylamide)(PNIPAAm)-based thermo-responsive surfaces can switch their wettability(from wettable to non-wettable) and adhesion(from sticky to non-sticky) according to external temperature changes. These smart surfaces with switchable interfacial properties are playing increasingly important roles in a diverse range of biomedical applications; these controlling cell-adhesion behavior has shown great potential for tissue engineering and disease diagnostics. Herein we reviewed the recent progress of research on PNIPAAm-based thermo-responsive surfaces that can dynamically control cell adhesion behavior. The underlying response mechanisms and influencing factors for PNIPAAm-based surfaces to control cell adhesion are described first. Then, PNIPAAm-modified two-dimensional flat surfaces for cell-sheet engineering and PNIPAAm-modified three-dimensional nanostructured surfaces for diagnostics are summarized. We also provide a future perspective for the development of stimuli-responsive surfaces.
There are many elaborate masterpieces exist in natural world. Learning from nature, people developed serial intelligent biomimetic devices. Biomimetic smart nanochannels received widespread attention for mimicking biological processes in bodies. Excellent stability, tailorable surface characteristics and nano-size effects rend polymer single nanochannel an ideal candidate for constructing sensitive and reproducible biosensors. Nanochannels are responsive for special analytes while appropriate recognition elements are modified in channels wall. In this review, we summarized recent works in contructing biosensors that are using polymer single nanochannels for detecting various analytes.
HOU GuangLeiPENG ZhiJianTIAN YeZHANG HuaChengJIANG Lei
