Photochemical additive manufacturing technologies can
produce complex
geometries in short production times and thus have considerable potential
as a tool to fabricate medical devices such as individualized patient-specific
implants, prosthetics and tissue engineering scaffolds. However, most
photopolymer resins degrade only slowly under the mild conditions
required for many biomedical applications. Herein we report a novel
platform consisting of amino acid-based polyphosphorodiamidate (APdA)
monomers with hydrolytically cleavable bonds. The substituent on the
α-amino acid can be used as a handle for facile control of hydrolysis
rates of the monomers into their endogenous components, namely phosphate
and the corresponding amino acid. Furthermore, monomer hydrolysis
is considerably accelerated at lower pH values. The monomers underwent
thiol-yne photopolymerization and could be 3D structured via multiphoton
lithography. Copolymerization with commonly used hydrophobic thiols
demonstrates not only their ability to regulate the ambient degradation
rate of thiol-yne polyester photopolymer resins, but also desirable
surface erosion behavior. Such degradation profiles, in the appropriate
time frames, in suitably mild conditions, combined with their low
cytotoxicity and 3D printability, render these novel photomonomers
of significant interest for a wide range of biomaterial applications.