Browsing by Author "Tsubokawa, Hiroshi"

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In situ laser micropatterning of proteins for dynamically arranging living cells
(2013)
Okano, Kazunori
;
Matsui, Ai
;
Maezawa, Yasuyo
;
Hee, Ping-Yu
;
Matsubara, Mie
This study shows the modification of the surface of polymer-layered glass substrates to form biofunctional micropatterns through femtosecond laser ablation in an aqueous solution. Domains of micrometer size on a substrate can be selectively converted from proteinphobic (resistant to protein adsorption) to proteinphilic, allowing patterning of protein features under physiological aqueous conditions. When femtosecond laser pulses (800 nm, 1 kHz, 200-500 nJ per pulse) were focused on and scanned on the substrate, which was glass covered with the proteinphobic polymer 2-methacryloyloxyethylphosphorylcholine (MPC), the surface became proteinphilic. Surface analysis by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) reveals that the laser ablates the MPC polymer. Extracellular matrix (ECM) proteins were bound to the laser-ablated surface by physisorption. Since femtosecond laser ablation is induced under physiological aqueous conditions, this approach can form micropatterns of functional ECM proteins with minimal damage. This method was applied to pattern collagen, laminin, and gelatin on the substrate. Removal of an ECM protein from the substrate followed by replacement with another ECM protein was achieved on demand at a specific location and time by the same laser ablation method. Living cells adhered to the fabricated domains where ECM proteins were arranged. The modification of patterning during cell culture was used to control cell migration and form arrays of different cells.
Induction of Cell-Cell Connections by Using in situ Laser Lithography on a Perfluoroalkyl-Coated Cultivation Platform
(2011-03-21)
Okano, Kazunori
;
Yu, David
;
Matsui, Ai
;
Maezawa, Yasuyo
;
Hosokawa, Yoichiroh
This article describes a novel laser-directed microfabrication method carried out in aqueous solution for the organization of cell networks on a platform. A femtosecond (fs) laser was applied to a platform culturing PC12, HeLa, or normal human astrocyte (NHA) cells to manipulate them and to facilitate mutual connections. By applying an fs-laser-induced impulsive force, cells were detached from their original location on the plate, and translocated onto microfabricated cell-adhesive domains that were surrounded with a cell-repellent perfluoroalkyl (R(f)) polymer. Then the fs-laser pulse-train was applied to the Rf polymer surface to modify the cell-repellent surface, and to make cell-adhesive channels of several mm in width between each cell-adhesive domain. PC12 cells elongated along the channels and made contact with others cells. HeLa and NHA cells also migrated along the channels and connected to the other cells. Surface analysis by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) confirmed that the Rf polymer was partially decomposed. The method presented here could contribute not only to the study of developing networks of neuronal, glial, and capillary cells, but also to the quantitative analysis of nerve function.
Laser-Assisted Control of Protein Adsorption for Dynamically Arranging Viable Cells
(2013)
Okano, Kazunori
;
Matsui, Ai
;
Maezawa, Yasuyo
;
Matsubara, Mie
;
Hosokawa, Yoichiroh
Polymers and proteins covering glass surface were ablated by femtosecond laser pulses under physiological aqueous condition. The prepared micropatterns of proteins were confirmed by fluorescence imaging and their cell adhesion characteristics was demonstrated.