Additively Manufactured Semiflexible Titanium Lattices as Hydrogel Reinforcement for Biomedical Implants

Abstract

Hydrogels are one of the most widespread biomaterials used in tissue engineering. However, they possess weak mechanical properties and are often unstable in load‐bearing applications in vivo. A novel class of flexible Ti–6Al–4V titanium alloy lattices manufactured using laser powder bed fusion (L‐PBF) serves as a tunable reinforcement for hydrogels, providing them with additional mechanical stability and flexibility, while ensuring biocompatibility. A study on the design parameters of the structural elements of the lattices is performed to evaluate their influence on the mechanical properties of the structure. Mechanical testing of Ti–6Al–4V lattices shows a compressive modulus ranging from 38.9 to 895.5 kPa in the flexible direction. In the other two directions, the lattices are designed to have minimal flexibility. Lattices embedded in a 1% agarose hydrogel show a strain‐rate‐dependent, viscoelastic behavior given by the hydrogel component with the additional stiffness of the titanium lattice. Stress distribution upon loading is simulated using finite element analysis (FEA) and compared to experimental data using multiple regression statistical analysis. As a proof of concept, an intervertebral spinal disc implant is designed with mechanical properties matching the compressive moduli of the nucleus pulposus and anulus fibrosus reported in the literature.

Shape-defining alginate shells as semi-permeable culture chambers for soft cell-laden hydrogels

“…For example, different hydrogel concentrations can be used together to provide both structural support and a soft hydrogel matrix for cells to proliferate [8]. Alternatively, adding reinforcement structures to soft hydrogels generates structures with stiff macroscopic properties that still retain a softer microenvironment for cells [9][10][11]. Other approaches focus on the inclusion of nanoparticles or nanofibers to the hydrogel mixture to generate viscous and stiff composite hydrogels [12][13][14].…”