Development of a Prototype Tissue-Specific Photopolymerizable Bioengineered Matrix Utilizing Temperature-Responsive Copolymeric Hydrogels for Multi-Material Volumetric Photopolymerization

Abstract

This study addresses key limitations in tissue engineering—specifically, the inability of traditional additive bioprinting methods to fabricate complex, multi-material structures with the resolution and speed required for functional tissues. Volumetric photopolymerization methods, such as xolography and pulsed holographic photopolymerization, offer superior resolution and simultaneous whole-volume fabrication but require advanced materials. We present a prototype "liquid bioengineered tissue" matrix designed for such volumetric methods, specifically targeting bioengineered endometrium. The innovation is a biocompatible, temperature-responsive, photopolymerizable hydrogel based on Poly(N-Isopropylacrylamide) (PNIPAAm), with a Lower Critical Solution Temperature (LCST) near body temperature. This enables a phase transition from a homogeneous solution at room temperature to a precipitated state under physiological conditions. The matrix is made tissue-specific by conjugating solubilized glycoproteins and glycosaminoglycans from endometrial Extracellular Matrix (ECM) into the hydrogel. To enhance biological activity, a glycoprotein fraction from platelet lysate is chemically incorporated, extending growth factor stability. Synthesis involved radical polymerization of N-isopropylacrylamide to form PNIPAAm, enzymatic digestion of endometrial ECM, and subsequent component conjugation. The resulting hydrogels were purified and characterized. Particle size analysis confirmed nanoparticle formation suitable for a "morphogenetic matrix". The hydrogels remained optically transparent below the LCST, which is critical for volumetric photopolymerization. This PNIPAAm-based matrix, incorporating tissue-specific ECM components and platelet lysate factors, represents a foundational step towards enabling high-resolution volumetric photopolymerization for complex tissue engineering. While realizing pulsed holographic photopolymerization remains challenging, this matrix provides essential compatible materials for future volumetric bioprinting advances.