Intelligent Measurement and Control of Tissue Collagen for Bone Tissue Engineering

Second-harmonic-generation (SHG) microscopy is a new tool for observing the collagen fiber in tissue in vivo. However, conventional SHG microscopy equipped with 100-fs pulse laser is insufficient to visualize collagen fiber produced by cultured cell with high contrast because of low nonlinear susceptibility x(2) in low-order-structured, immature collagen. To enhance the image contrast while avoiding the sample damage, one has to increase a peak power of the laser light while maintaining the same average power as the 100-fs laser. In this paper, we enhanced the sensitive of SHG microscopy by use of a 10-fs Ti:Sapphire laser and succeeded to visualize collagen fibers produced by the cultured osteoblasts in vivo