Rapid and Direct Cell-to-Cell Adherence Using Avidin-Biotin Binding System: Large Aggregate Formation in Suspension Culture and Small Tissue Element Formation Having a Precise Microstructure Using Optical Tweezers

Nobuhiko Kojima, Ken Miura, Tomoki Matsuo, Hidenari Nakayama, Kikuo Komori, Shoji Takeuchi, and Yasuyuki Sakai

Effectively organizing isolated cells to tissue elements having an appropriate microstructure is a fundamental issue in future tissue engineering, but biological cell-to-cell adhesion is too weak to assemble single cells directly. In order to overcome the difficulty, we applied an Avidin-Biotin Binding System (ABBS) to cell surfaces, and avidinylated and biotinylated cells could mutually bind in the short time they were mixed together. Unlike conventional intact cells, ABBS helped make larger spheroids. Interestingly, avidinylated and biotinylated cell adherence occurred within 1 sec using laser trapping, enabling single cell manipulation. We showed precise, direct single-cell-based tissue assembly using ABBS and optical tweezers, followed by damage-free tissue culture. The combination of ABBS and single cell manipulation has considerable potential for use in application such as tissue engineering, regenerative medicine, and drug screening system.

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Massive Parallel Assembly of Microbeads for Fabrication of Microtools Having Spherical Structure and Powerful Manipulation by Optical Tweezers

Hisataka Maruyama, Ryo Iitsuka, Kazuhisa Onda, and Fumihito Arai

Production of functional microtools having an arbitrary shape by self-assembly of microparticles and heat treatment above the glass transition temperature of the microparticles was developed. Polystyrene microbeads were used as a material of the microtool. A solution including microparticles was dispersed onto the silicon substrate having microtool patterns fabricated by photolithography and etching. Dispersed particles were introduced to the pattern by gravity force. Microparticles in the pattern aggregate autonomously by surface tension through evaporation of the solution. Aggregated microparticles were fused by heating above the glass transition temperature (100°C). Fused microparticles were detached from the pattern by ultrasonic treatment and used as microtools. Produced microtool has spherical part since the microtool is made of microparticles. Spherical part is suitable for trapping point of optical tweezers. We demonstrated production of microtools using self-assembly and manipulation of the fabricated microtool on a chip.

DOI