Cross-shaped nanoporous poly(methyl methacrylate) fibers for selective adsorption of β ₂ -microglobulin and other middle-molecular-weight proteins

Background: Dialysis-related amyloidosis (DRA) is a serious complication in chronic kidney disease patients on long-term dialysis, caused by β 2 -microglobulin (β 2 -MG) accumulation, and remains challenging owing to the growing dialysis population and extended treatment duration. Objectives: To develop and evaluate stereocomplex poly(methyl methacrylate) (PMMA) adsorbent fibers with optimized cross-sectional and nanoporous structures for efficient, selective β 2 -MG removal. Methods: Structured PMMA fibers were fabricated via dry-wet spinning. The adsorption performance of optimized fibers was evaluated with serum containing β 2 -MG and other solutes, using scanning electron microscopy (SEM), three-dimensional transmission electron microscopy (3D-TEM), and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Pressure loss simulations compared fiber- and bead-packed columns. Results: Fibers with 12–15 nm pores exhibited maximal β 2 -MG adsorption. Cross-shaped fibers exhibited the highest blood-contact surface area and adsorption capacity. A thin surface-dense layer (<0.1 μm) improved β 2 -MG diffusion while limiting albumin uptake. TOF-SIMS confirmed uniform β 2 -MG penetration, with albumin confined near the fiber surface. Adsorption exceeded 50% for mid-weight proteins (~52 kDa), including IL-6, α 1 -microglobulin (α 1 -MG), and TNF-α. Pressure loss simulations showed that fiber-packed columns had lower resistance than bead-packed columns. Conclusions: Optimized cross-shaped PMMA fibers enable efficient, selective β 2 -MG removal and favorable flow dynamics for hemoperfusion therapies targeting mid-weight uremic toxins.