Date of Award

6-7-2026

Document Type

Thesis

Publisher

Santa Clara : Santa Clara University, 2026

Department

Bioengineering

First Advisor

Maryam Mobed-Miremadi

Abstract

Chronic kidney disease affects approximately 800 million people worldwide, with more than 800,000 Americans living with end-stage kidney disease. Peritoneal dialysis provides patients with greater :flexibility and independence than traditional hemodialysis, but it is limited by the buildup of urea in the dialysate, which requires frequent fluid exchanges. Developing a system that continuously regenerates dialysate could help improve the efficacy of this treatment.

In this study, we developed the PeriDevice, a compact packed-bed reactor designed to remove urea from dialysate through enzymatic degradation. The 3D-printed device, using stereo lithography, filled with alginate microcapsules ( d = 1.5 mm) containing urease. The reactor design (73.5 mm length, 40.5 mm width, with 31 channels) was based on concepts including convection-diffusion-reaction transport, flow through porous media, and packed-bed permeability. Since dialysate flows through a bed of microcapsules, factors such as residence time, mass transfer, and urea diffusion into the capsules were expected to affect urea removal. Multiple reactor designs were tested to improve flow distribution, increase the active reactor volume, reduce pressure losses, prevent leakage, and maintain microcapsule integrity. Different microcapsule formulations were also investigated using calcium chloride and barium chloride crosslinking, with poly-L-lysine and genipin coatings evaluated for their ability to improve enzyme retention and mechanical stability.

The PeriDevice was tested using simulated uremic dialysate containing 100 mg/dL urea and a programmable syringe pump to control flow conditions. The final reactor design operated without leakage at therapeutic flow rates up to 110 mL/min and was successfully integrated into an automated circulation system. Separate testing confirmed that the encapsulated urease remained active after immobilization. When tested as a complete system, the reactor achieved a maximum urea removal efficiency of 26%. Although the target of 80% urea removal, calculated in terms of conversion, was not reached, the results suggest the potential of using immobilized enzymes for continuous dialysate regeneration. This work provides the foundation for additional multivariate optimization efforts encompassing Peridevice reactor design, microcapsule membrane formulation, and enzyme immobilization.

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