Spatiotemporal Control of Formation of Dynamic Protein Fiber Assemblies via Photophysical Effects of a Focused Laser Beam

Spatiotemporal control of the formation of highly ordered, protein fiber assemblies via photophysical effects of a focused laser beam is demonstrated. Focused irradiation with a continuous laser beam at an air/solution interface can accumulate tubulin proteins at/around the laser focus, which leads to the formation of highly ordered microtubule assemblies. The assemblies can exhibit various dynamic behaviors such as translational motion, bundling, and cilia-like beating with motor protein and chemical energy, revealing their biological activities. The protein accumulation with a focused laser beam is attributed to the local increases in concentration and temperature produced through two-types of photophysical effects, i.e., laser trapping by optical forces and heat generation by photoabsorption, which can fabricate complex microtubule assemblies without specific photochemical reactions and deuterated water solvents (i.e., physiological conditions). We anticipate that this laser method will provide fundamental insights into the structure-motion relationship of biomolecular assemblies and expand the bioengineering of protein assemblies.