Special Poster Session Biofabrication
Natural biological tissue usually contains a 3-dimensional architecture that is comprised of different cell types and structures of intracellular and extracellular matrix. Most importantly, in these well-optimized systems, defined function requires defined structure on macro- as well as microscopic levels. Biofabrication attempts to reproduce 3D structures of natural tissues by a variety of modern fabrication techniques, the foremost being 3D-Printing. However, a deep understanding of the target tissue template, ranging from cell population type to extra- and intracellular matrix structure, is required to allow for biomimetic replicate of tissue form and function.
A variety of microscopy techniques is available to answer the questions of template structure and construct quality, however, most commonly applied techniques have several drawbacks (e.g. removal of water, necessity of external dyes, photon scattering, low optical resolution) that complicate 3D imaging of living samples or may even alter sample structure due to light-matter interactions.
We use Multi-Photon Excitation Microscopy as a technique with the potential to provide in-depth tissue template analysis as well as quality control of biofabricated constructs.
This results in two major advantages of the system:
- Long wavelength light may be used to excite fluorochromes. This allows for the exploitation of the near infrared (NIR) optical window in biological tissue for excitation, thereby reducing absorption and scattering and effectively increasing penetration depth.
- The signal emission occurs confined in all three spatial dimensions as the signal intensity If is proportional to the excitation light intensity Iex to the power of n, with n being the number of interacting photons (If ∝ (Iex)n). Thus, only very high intensity illumination in the focal spot produces a signal.
- Availability of additional contrast caused by elastic optically nonlinear frequency multiplication effects, such as Second- or Third-Harmonic-Generation (SHG, THG), that are produced intrinsically by certain biopolymer structures, such as fibrous collagen I or myosin II.