Multimaterial Segmented Fiber Printing for Gradient Tissue Engineering

In this work, we present a printing method to fabricate scaffolds consisting of multimaterial segmented fibers. Particularly, we developed a reproducible printing process to create single fibers with multiple discrete compositions and control over the distribution of particulate ceramics—namely hydroxyapatite (HA) and β-tricalcium phosphate (TCP)—within poly(ɛ-caprolactone)-based composite scaffolds. Tensile testing revealed that the mechanical integrity of individual segmented fibers was preserved compared with nonsegmented fibers, and microcomputed tomography and thermal analysis confirmed the homogeneous distribution of ceramics incorporated in the fiber compositions. Moreover, we printed and characterized composite scaffolds containing model inverse radial gradients of HA and TCP that could serve as a tunable platform to control the degradation rate of the scaffolds and match bone tissue ingrowth. The morphology of the gradient scaffolds was assessed, and their bulk compressive mechanical properties were found to be in the same range as human trabecular bone. Finally, scaffold degradation was monitored for up to 10 weeks in phosphate-buffered saline pH 7.4 and 0.1 M HCl solution, and scaffolds containing TCP in their composition showed increased degradation compared with those containing HA. This work provides a new methodology for the fabrication and characterization of porous scaffolds containing designer composition gradients that could serve as a platform for the preparation of complex scaffolds for tissue engineering applications.