Research group of Professor Hou Xu of Xiamen University: anomalous ion transport behavior and dynamic regulation of ion rectification in curvature driven dynamic nano confined space

The transport of different ions is controlled by the cell membrane, and its regulation mechanism depends not only on the intrinsic structure of the channel and the physical and chemical properties of the inner surface, but also on the dynamic shape changes in their life process As a platform to simulate the ion transport performance of biological nano channel, the artificial nano channel membrane provides potential tools and scientific guidance for many applications in life science and material science In recent years, many artificial nano channel membranes have been developed for nanofluidics and biosensors, which regulate ion transport mainly by modifying functional molecules on the inner surface of the nano channel as stimulation response layer However, the dynamic shape change of biological nano channels is also very important, for example, in the physiological and pathophysiological process, there will be non-stop bending of nano channels between cells At present, the artificial nanochannels mainly modify the functional molecules on the inner surface of the nanochannels by static method to achieve the stimulation response Therefore, the adjustment of ion transport in static nano channels is realized by adjusting their effective channel size The newly reported current dynamic tunable nanopore or nanochannel is still to control the effective pore size through surface modification to achieve the purpose of adjusting ion current Therefore, it is still a challenging task to give the artificial nano channels dynamic shape change and fixed channel size to control ion transport Due to the selection of materials and the problem of nano scale space blocking, the current dynamic nano channel preparation method can hardly take both flexibility and nano size into account Although adjustable elastic nanochannels have been reported, the size of these nanochannels is more than three orders of magnitude of ion size, and they do not involve axial deformation Recently, Professor Hou Xu of Xiamen University further developed the concept of dynamic nano channel system and reported a dynamic curvature nano channel membrane system The system has an abnormal effect which depends on voltage, concentration and ion size The reversible conversion of ion rectification effect can be controlled in real time by adjusting curvature This is a new way to adjust the ion rectification in real time by using the dynamic change of channel curvature to adjust the ion transport in the nano channel This dynamic method can be used to construct the smart nano channel system, which has a broad application prospect in the fields of flexible nano flow control system, ion rectifier and nano generator Relevant research results were published in adv mater (DOI: 10.1002 / ADMA 201805130), an international famous journal, under the title of "dynamic curvature nachannel based membrane with acoustic transport behaviors and reversible correction switch" Brief introduction of Professor Hou Xu's research group: Professor Hou Xu has one professor, one ichem fellow, one specially appointed deputy researcher, four specially appointed assistant researchers, three postdoctors, six doctors and 11 masters, relying on the State Key Laboratory of solid surface physics and chemistry of Xiamen University and the collaborative innovation center of energy materials chemistry The current research work of the research group includes: colloid and interface chemistry, bionic and intelligent multi-scale pore / channel system, membrane science and technology, microfluidics, interface science, physical chemistry, electrochemistry and micro nano manufacturing applied to energy conservation and biomedicine Introduction to Professor Hou Xu, professor and doctoral supervisor of School of chemistry and chemical engineering, Xiamen University In 2006 and 2011, he received bachelor's degree and doctor's degree from Sichuan University and national nano center of Chinese Academy of Sciences respectively, and his tutor was researcher Jiang Lei In 2012, he carried out postdoctoral research in aizenberg research group of Harvard University, and joined Xiamen University in October 2015 He is an outstanding foreign talent introduced by Xiamen University relying on the youth program of national overseas high-level talent introduction program He has successively studied and worked in China National Nano Science Center, Wyss Bionic Engineering Research Institute of Harvard University, HST center of Harvard Massachusetts Institute of technology, State Key Laboratory of solid surface physics and chemistry of Xiamen University and other international first-class research institutions, mainly engaged in micro / nano scale porous membrane science and technology research At present, two international academic works have been published, and 28 papers have been published as the first and corresponding author, including nature (1), NAT Rev Mater (1), SCI Adv (1), NAT Commun (1), chem SOC Rev (1), angel Chem Int ed (2), J am Chem SOC (3), adv.mater (5) Chapter 1 At the same time, 11 national patents and 3 American patents were applied for The number of citations is more than 3100, and the h-index is 27 He has won the youth Chemistry Award of China Chemical Society, the key special chief scientist of national key R & D Program "nanotechnology", Fujian Outstanding Youth Fund (2018), the 12th batch of national "Thousand Talents Program" young talents (2016), Fujian Hundred Talents Program (2017), the future leader of SciFinder chemical field of American Chemical Society (2014, global 18 , Harvard University postdoctoral Career Development Award (10 in the University), Springer Paper Award (2013), excellent doctoral dissertation of Chinese Academy of Sciences (2012), first prize of national colloid and interface chemistry outstanding achievement award (2 in the country), national Lucasian outstanding graduate Award (2011), etc Academic posts: Deputy Director of physical chemistry of Youth Committee of China Chemical Express (2017 to date), young Editorial Committee of Applied Chemistry (2017 to date), deputy director of Youth Committee of State Key Laboratory of solid surface chemistry (2017 to date), and the first batch of Minjiang science communication scholars (2017 to date) Cutting edge research achievements: the abnormal ion transport behavior in curvature driven dynamic nano confined space and the real-time dynamic regulation of ion rectification Professor Hou Xu of Xiamen University further developed the concept of dynamic nano channel system, and reported a dynamic curvature nano channel membrane system The process of preparing the dynamic nano channel film is shown in Figure 1a, and the film thickness is about 15 microns In this paper, the carbon nano channels (CNS) with an inner diameter of about 8 nm are embedded in the deformable polydimethylsiloxane (PDMS) to form a bendable axial nano channel By means of pre bending and length adjustment, the asymmetric bending nano channels are constructed The shape of these channels is always asymmetric in the later deformation process At the same time, the uncurved nanochannels were prepared to study their ion transport properties during dynamic deformation The port grafting method is used to ensure that only cations can pass through the nanochannels, which is conducive to the study of the effect of the deformation of the nanochannels The authors found that the dynamic deformation of the nanochannels showed abnormal ion transport behavior (Fig 1b) The rectification ratio is defined as the current ratio under negative bias and positive bias in the nano channel Under the condition of low voltage (V, curve II), low concentration (C, curve I) or small size ions (s, curve III), the deformation of the nano channel will become the main factor affecting ion transport, and has different influence laws However, at high voltage / concentration / ion size, deformation has almost no effect on the ion rectification ratio, similar to the unbending nano channel: with the increase of voltage / concentration / ion size, the ion current is in a stable linear increase state (Fig 1c) Therefore, under the condition of low voltage / concentration / ion size, the dynamic control of ion rectification can be realized by the active deformation and recovery of nano channels to meet the specific needs of ion transmission or realize the dynamic switching of ion rectification Figure 1 Design of dynamic nano channel film and anomalous ion transport behavior (a) The preparation process of the deformable nanochannels; (b) the ion transport behavior in the dynamic nanochannels; (c) the anomalous ion transport behavior and the dynamic transformation diagram in the dynamic nanochannels (source: adv mater.) in order to obtain the asymmetric curved nano channel film, the author chooses pre bending as the first step to provide the carbon nanotube array with preset curvature according to the method in Figure 2A The curvature of the CNT array is 1.7 ± 0.04 (estimated by dividing the film thickness by the film length) at a horizontal pressure of 500 n Subsequently, the authors obtained straight and curved carbon nano channels by infiltrating and curing PDMS and ultra-thin sections (Fig 2a) The height of the S-shaped nano channel produced by the pre bending process is about 20 μ M the thickness of the film is cleverly designed as 15 μ m to ensure that the curvature of the nano channel is asymmetric By plasma oxidation, the port of carbon nano channel was opened and carboxyl group was grafted, and the hydrophobic interface was changed into hydrophilic interface The adsorption capacity of the plasma treated carbon nano channel is one order of magnitude higher than that of the commercial nano channel (polycarbonate porous membrane, aperture of 100 nm) (Fig 2b) According to TMS theory, KCl solution on both sides of the membrane has different concentration difference The selectivity of the membrane is calculated by measuring the potential difference on both sides In the experiment, the fitting curve of Φ to log (α L / α R) in Fig 2C shows that the plasma treated membrane has good cation selectivity, while the untreated membrane has almost no selectivity Fig 2 Preparation and cation selectivity of asymmetric curved nanochannel films (a) The preparation of asymmetric curved and straight nanochannels; (b) characterization of nitrogen adsorption desorption isothermal curve and pore size; (c) characterization of ion selective properties of nanochannels (source: adv mater.) the research results were published in the internationally famous journal adv mater (DOI: 10.1002 / ADMA 201805130) The first author of the paper is Wang Miao, a special associate researcher of Xiamen University, and the corresponding author is Professor Hou Xu of Xiamen University Nowadays, people and scientific research have been paid more and more attention in the economic life China has ushered in the "node of science and technology explosion" Behind the progress of science and technology is the work of countless scientists In the field of chemistry, in the context of the pursuit of innovation driven, international cooperation has been strengthened, the influence of Returned Scholars in the field of R & D has become increasingly prominent, and many excellent research groups have emerged in China For this reason, CBG information adopts the 1 + X reporting mechanism CBG information, chembeangoapp, chembeango official microblog, CBG wechat subscription number and other platforms jointly launch the column of "people and scientific research", approach the domestic representative research group, pay attention to their research, listen to their stories, record their demeanor, and explore their scientific research spirit.