Advancements in the understanding of neurophysiology and the complexity of neural networks have led to a pressure for improvements in devices and materials that are able to interface with soft neural tissue chronically while minimally disturbing the surrounding tissue. Traditional neural prosthetics, including those patterned on silicon or polyimide, rely on stiff substrates for insertion. However, these materials are grossly mismatched in terms of modulus when compared to the tissues they stimulate and record from. Shape memory polymers (SMPs) have proven a more compatible substrate, leading to neural prosthetics that can both insert reliably while softening considerably after some time in vivo. However, a challenge with these systems remains in the permanent shank site created during implantation. If the permanent scar site volume could be reclaimed after implantation, the intimate connection between neurons and implant would increase the recording sensitivity of such an implant. In this study a hydrolytically unstable monomer containing an anhydride linkage is used to fabricate SMP substrates with highly tunable thermomechanical properties and degradation rates. Using a base system comprising the stoichiometric balance of the thiol tris[2-(3-mercaptopropionyloxy)ethyl] isocyanurate (TMICN) and the alkene 1,3,5-Triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TATATO), increasing ratios of methacrylic anhydride (MAH) were added to the base system. The resultant networks were tested using dynamic mechanical analysis (DMA), which showed that subsequent addition of up to 20wt% MAH demonstrated little effect on rubbery modulus (Gr) and glass transition (Tg). With these initial results, these thiol-ene/anhydride networks show promise as a high-Tg, tunably-degradable system with which substrates for transient neural electronics can be quickly and reliably fabricated.

Thiol-ene/anhydride networks for tunably degradable neural substrates

249th National Meeting (2015)

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