Takeshi Fukuma1
Kanazawa University1
Atomic force microscopy is a powerful technique that can visualize atomic- or molecular-scale structures, dynamics and properties even in liquids regardless of the conductivity of the sample. In the past decade, there has been significant advancement in the in-liquid AFM techniques. Owing to the development of low noise cantilever deflection sensors[1] and small amplitude operation mode, atomic or molecular resolution can be achieved routinely even with dynamic-mode AFM such as frequency modulation[2] and amplitude modulation AFM (FM- and AM-AFM). This allowed us to visualize subnanoscale surface structures of various biological samples[3]. In addition, the tip scanning scheme has been expanded from 2D to 3D[4] and now we can visualize the 3D distribution of water (i.e., hydration structures), organic solvents, ionic liquids and flexible molecular chains[5-7]. These unique capabilities should be particularly useful in the studies of nano-bio interfaces, where biomolecules, water and ions interact with each other to induce various biological phenomena. However, their applications to the studies on biomaterials have yet been limited. In this presentation, I would like to present our recent works to explore applications of high-resolution in-liquid AFM techniques to studies on nano-bio interfaces. Examples include molecular-scale investigations on cellulose[8] and chitin[9] nanocrystals and self-assembled structures of short peptides on graphite[10].<br/><br/>[1] T. Fukuma, M. Kimura, K. Kobayashi, K. Matsushige, and H. Yamada, Rev. Sci. Instrum. <b>76</b>, 053704 (2005).<br/>[2] T. Fukuma, K. Kobayashi, K. Matsushige, and H. Yamada, Appl. Phys. Lett. <b>87</b>, 034101 (2005).<br/>[3] H. Asakawa, K. Ikegami, M. Setou, N. Watanabe, M. Tsukada, and T. Fukuma, Biophys. J. <b>101</b>, 1270 (2011).<br/>[4] T. Fukuma, Y. Ueda, S. Yoshioka, and H. Asakawa, Phys. Rev. Lett. <b>104</b>, 016101 (2010).<br/>[5] H. Asakawa, S. Yoshioka, K. Nishimura, and T. Fukuma, ACS Nano <b>6</b>, 9013 (2012).<br/>[6] T. Ikarashi<i> et al.</i>, ACS Applied Nano Materials <b>4</b>, 71 (2021).<br/>[7] T. Ikarashi, K. Nakayama, N. Nakajima, K. Miyata, K. Miyazawa, and T. Fukuma, ACS Appl Mater Interfaces <b>14</b>, 44947 (2022).<br/>[8] A. Yurtsever, P. X. Wang, F. Priante, Y. Morais Jaques, K. Miyazawa, M. J. MacLachlan, A. S. Foster, and T. Fukuma, Sci. Adv. <b>8</b>, eabq0160 (2022).<br/>[9] A. Yurtsever, P. X. Wang, F. Priante, Y. Morais Jaques, K. Miyata, M. J. MacLachlan, A. S. Foster, and T. Fukuma, Small Methods <b>6</b>, 2200320 (2022).<br/>[10] A. Yurtsever, L. Sun, K. Hirata, T. Fukuma, S. Rath, H. Zareie, S. Watanabe, and M. Sarikaya, ACS Nano <b>17</b>, 7311 (2023).