My Life in NCNST——Xu Hou(China)
When I was a child, I was always greatly interested in Nobel Prize Winners' stories, such as Marie Curie, Albert Einstein and Linus Pauling. Their interesting and wonderful lives inspire my love of science. So when I was in high school, I chose to be a science student. Later I graduated from Sichuan University, majoring in Biomedical Engineering. I was lucky to get the postgraduate recommendation from Sichuan University to pursue my PhD in Graduate University of Chinese Academy of Sciences. Since then, I began my academic career at National Center for Nanoscience and Technology (NCNST) in 2006.
In 2007, I successfully passed through the first year of my school life, and I selected courses related to my future research directions, such as Nanochemistry (92 points) , Materials Chemistry (93 points) , Inorganic Porous Material ( 94 points), et al. as my degree courses, and Surface Reactions and Catalysis (90 points), Chemical Biology New Progress (99 points), et al. as my non-degree courses. And I also successfully passed the PhD degree of English test.
After the school life, I began my research at NCNST. I think students were very lucky to have chances to face to face communicate with academicians of the Chinese Academy of Sciences and lots of great scientists all over the world at our center. From these communications, I learned a lot about scientific knowledge & the truth in life, and that enlarged my view. At that time, I hope sincerely to do something for scientific field in future. Meanwhile, our center provides us a variety of community activities, such as chorus, football team, academic committee, Center Open Day et al. These activities not only relax us after our research works, but also improve our body and increase communication between students and teachers. For example, I joined the academic committee, as one of the eight members of committee, I have the opportunity to be an editor in chief of Student Communication of National Center for Nanoscience and Technology to build a bridge for communication between teachers and students. In addition, I was very honored to serve as a student representative on the Center Open Day to give a popular science lecture to Beijing residents.
In 2008, I was working on biomimetic intelligent nanomaterials research. Learning from nature has inspired us to create novel artificial materials that allow us to better understand and imitate biology. Bio-inspired, in particular, owes much of its current development to advance in materials science and creative smart system designs. The development and application of bio-inspired nanochannels is a burgeoning new area of research. The important ion transport properties and potential applications of smart nanochannels continue to drive new developments in this area of materials science for various real-world applications, such as biosensors, energy conversion systems and nanofluidic devices. As outlined above, there is much scope for the design and development of new bio-inspired nanochannels with more complicated approach. There is particular potential for future collaboration between chemists, physicists, biologists and manufacturers –indeed, this will be essential in order for this area to flourish. On that occasion, there had been rapid progress in developing the smart nanochannels [Nat. Nanotechnol., 2008, 3, 73], such as specific ions (Nat. Nanotechnol., 2008, 3, 51), light (JACS, 2006, 128, 13553), pH (ACS Nano, 2009, 3, 603) and applied force (Nat. Mater., 2007, 6, 424). I participated in designing and building the pH gating DNA-nanochannel system which was controlled by collective folding of structured DNA molecules responding to the external stimulus, provided an artificial counterpart of switchable protein-made nanochannels (JACS, 2008, 130, 8345; highlight by Nature, 2008, 453, 960). In the second half of this year, I developed a biomimetic potassium responsive nanochannel system by modifying G-Quadruplex DNA, which is highly ordered DNA structure derived from G-rich sequences formed by tetrads of hydrogen-bonded guanine bases (JACS, 2009, 131, 7800; highlight by Nature China, 2009). Among the quadruplex-forming sequences, the human telomeric sequence d[AGGG(TTAGGG)3] has attracted tremendous interest due to its importance at telomere maintenance and cell aging or death. It is very interesting to note that the Nobel Prize in Physiology or Medicine 2009 jointly to Elizabeth H. Blackburn, Carol W. Greider and Jack W. Szostak for the discovery of "how chromosomes are protected by telomeres and the enzyme telomerase" which is one of the most important research background of my research work. In my work, I experimentally demonstrate a novel biomimetic nanochannel which can achieve a K+ response within a certain ion concentration range. The situation of the grafting G4 DNA on a single nanopore can closely imitate the in vivo condition, because the G-rich telomere overhang is attached to the chromosome. Therefore, I believe this artificial system could promote a potential to conveniently study biomolecule conformational change in confined space by the current measurement which is significantly different from the nanopore sequencing. Moreover, such a system as a basic platform could potentially spark further experimental and theoretical efforts to simulate the process of ion transport in living organism and boost the development of bio-inspired intelligent nanopore apparatus such as biosensors, molecular filtration and nanofluidic devices.
In 2009, based on our previous work and inspired by photo-electric effects of halobacteria and retina, we constructed a novel photoelectric conversion system in which photo-sensitive molecules are used as light-driven ion pumps and generate ion transmembrane motive force (Adv. Funct. Mater., 2010, 20, 2636). Meanwhile, fabrication and application of artificial nanochannels are becoming the focus of attention because, compared with their biological counterparts, they offer greater flexibility in terms of shape, size, as well as surface properties. I developed a novel approach, which is not subject to the solution environment restriction, to prepare the stable and controllable continuous change of ionic current rectification of the chemical/structure asymmetric artificial nanochannels by ion sputtering technology (Small, 2010, 3, 361). Later, my tutor Prof. Lei Jiang and I, corporately, wrote a Perspective for ACS Nano titled “Learning from Nature: Building Bio-Inspired Smart Nanochannels”. In this perspective, the concept of these bio-inspired systems can be used to build novel, biologically inspired nanomachines with precisely controlled functions in the near future by design more complicated functional molecules. On the one hand, we can simulate the process of ion transport in living organism by using the biomimetic nanochannels. On the other hand, the artificial nanochannel systems can investigate the chemistry, structure sizes of biomolecules and promote a potential to conveniently study biomolecule conformational change in confined space by current measurement.
In 2010, based on the symmetric/asymmetric design, I further experimentally demonstrate a biomimetic asymmetric responsive single nanochannel system (J. Am. Chem. Soc., 2010, 132, 11736), which displays the advanced feature of providing simultaneous control over both pH- and temperature-tunable asymmetric ionic transport properties. Such a system, as an example, could potentially spark further experimental and theoretical efforts with different complicated functional molecules to exploit more complex “smart” nanochannel systems. Next, as many cases of ion channels are under asymmetric pH environment in real life, and how to realize biomimetic nanochannels smart control of ionic transport properties under asymmetric pH stimuli is a challenging task especially for developing functional nanofluidics under asymmetric conditions. I had developed a biomimetic single ion channel system which can smart ionic transport control under transmembrane asymmetric pH stimuli for the first time. I also participated in designing and developing a temperature responsive single nanochannel system; a simple enantioselective sensing device based on a single artificial β-cyclodextrin modified nanochannel system, which shows highly selective recognition of histidine enantiomers through monitoring of ionic current signatures; a photoelectric conversion system that absorbs solar light in the form of electrochemical potential by taking advantage of a smart-gating proton-driven artificial nanochannel; a novel F0F1-ATPase/nanoporous membrane system, in which the two sides of F0F1-ATPase were separated macroscopically for the first time.
In 2011, as a student volunteer, I participated in the China Nano international conference. This fantastic conference gave me a broad understanding of the most forward issues, which the most needed places are, and make me witness the elegances of many great masters, which will be a tremendous asset in my life. Moreover, our center let us participate in all aspects of this conference, which provide a good opportunity for our comprehensive improvement of our academic ability which will be very useful for our future research career.
Finally, I would like to express my sincere appreciation to our center for not only providing a high academic platform, but also a very happy living atmosphere. Especially, the graduate students office's teachers for their encouragement and the powerfully support in our daily life. Thank you very much!