Introduction

Multiphoton excited (MPE) fluorescence microscopy has been extensively used for biological imaging. With superior features such as minimum invasiveness, low photobleaching, and deep penetration depth, multiphoton microscopy has proven to be particularly suitable for three-dimensional (3D) imaging of thick tissues and living animals . Moreover, photopolymerization or photocrosslinking is a process which uses a combination of light with low molecular weight photoinitiators or photoactivators to trigger the respective reactions of polymerization or crosslinking . MPE photochemistry is the preferred technique to fabricate 3D tissue scaffolds and multiphoton microsurgery is also implemented in living tissues and cells.

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(a)Cultured COS7 cells transfected with eGFP. (b) SHG image of Collagen gel.