"Femtosecond laser nanoprocessing and biomedical applications" by Mitsuhiro Terakawa

Speaker:
Senior Assistant Professor Mitsuhiro Terakawa, Department of Electronics and Electrical Engineering, Keio University, Japan.

Seminar Title:
Femtosecond laser nanoprocessing and biomedical applications

Abstract:
High-precision laser processing of biomaterials by optical focused field and scattered field excited by femtosecond laser pulse will be presented.
The focused field generated around a nanostructure can concentrate optical energy into a nanoscale space, which enables precise processing. By using this technique, both “materials in the vicinity of nano-structures” and the “nano-structure itself” can be a target of laser ablation. As for the former case, the focused optical field under biodegradable polymer microspheres, which were conjugated on cells, provides cell membrane perforation of multiple cells by a single shot of 800 nm femtosecond laser pulse. As for the latter case, an enhanced optical field generated on a shell of hollow microcapsules realizes localized disruption of the shell without any doping with metals or dyes. Our method has potential to realize novel light-triggered controlled release.
The scattered field excited by a femtosecond laser pulse is also useful for nanoablation. Interference of a scattered wave and an incident wave provides the formation of a ripple structure on a material surface. We demonstrated ripple structure formation on a poly-L-lactic acid (PLLA), a biodegradable polymer, film by using femtosecond laser pulses. High-spatial frequency periodic structure whose periodicity is approximately 100 nm was fabricated on the surface of PLLA, which would contribute to scaffold fabrication in tissue engineering by controlling cell adhesive properties on the surface of biodegradable polymers.