Applications of Microstereolithography in Tissue Engineering

Microstereolithography is a microfabrication technique based on the light induced crosslinking
of a prepolymer according to a computer based design. The technology emerged in
the 1980’s as a rapid prototyping technique for the fabrication of small parts and devices. The
technique has evolved into an important research tool with a diverse range of applications
ranging from photonics to tissue engineering.
Two distinctly different branches of microstereolithography exist, differentiated by the
fundamental mechanics involved. The first branch, based on the initiation of curing by the
interaction of one photon of light with an initiator is a surface based technique. The
photosensitised prepolymer or ‘resin’ is illuminated typically with ultraviolet light in order to
cure the material within the first hundred micrometers of the surface and structures are
constructed in a layer-by-layer fashion. The second, more recently developed ‘branch’ of
microstereolithography was developed in the last decade of the twentieth century (although
the underlying principles were predicted as early as the 1930’s). Multiphoton polymerization
is a technique similar to multiphoton microscopy, in which two or more photons interact with
the photoinitiator within the lifetime of a virtual intermediate state, initiating curing. Due to
the low probability of this occurrence curing is only initiated in areas of very high photon
density, achieved by focusing a laser beam through a high numerical aperture objective into
the resin. Photocuring then occurs in the central area of the focal point, within the volume of
the resin.
The aim of this thesis was to investigate the applications of this technology (both one and two
photon) in tissue engineering, for the fabrication of bespoke tissue scaffolds and other
implantable devices. Photocurable oligomers based on bioresorbable materials already in
clinical use were also explored and their suitability for tissue engineering applications
investigated, with a focus on structuring and biocompatibility.