The performance of indwelling medical devices that depend on an interface with soft tissue is plagued by complex, unpredictable foreign body responses. Such devices—including breast implants, biosensors, and drug delivery devices—are often subject to a collection of biological host responses, including fibrosis, which can impair device functionality. This work describes a milliscale dynamic soft reservoir (DSR) that actively modulates the biomechanics of the biotic-abiotic interface by altering strain, fluid flow, and cellular activity in the peri-implant tissue. We performed cyclical actuation of the DSR in a preclinical rodent model. Evaluation of the resulting host response showed a significant reduction in fibrous capsule thickness (P = 0.0005) in the actuated DSR compared with non-actuated controls, whereas the collagen density and orientation were not changed. We also show a significant reduction in myofibroblasts (P = 0.0036) in the actuated group and propose that actuation-mediated strain reduces differentiation and proliferation of myofibroblasts and therefore extracellular matrix production. Computational models quantified the effect of actuation on the reservoir and surrounding fluid. By adding a porous membrane and a therapy reservoir to the DSR, we demonstrate that, with actuation, we could (i) increase transport of a therapy analog and (ii) enhance pharmacokinetics and time to functional effect of an inotropic agent. The dynamic reservoirs presented here may act as a versatile tool to further understand, and ultimately to ameliorate, the host response to implantable biomaterials.

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The electrode potential of zinc amalgams has been measured in potassium hydroxide solutions containing dissolved zincate. Curvature in the Nernst plots was observed at high zincate concentrations in agreement with the results of other workers. The curvature is explained as being due to the dependence of the hydroxyl and zincate ion activity on concentration in strong potassium hydroxide solutions. The data yield a value of −1.205V (vs. SHE) for the standard potential of the zinc, zincate ion electrode (I.U.P.A.C.—Stockholm convention) and −205.86 kcal for the free energy of formation of the zincate ion at 25°C.