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

Abstract

Background:

Dialysis-related amyloidosis (DRA) is a serious complication in chronic kidney disease patients on long-term dialysis, caused by β₂-microglobulin (β₂-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 β₂-MG removal.

Methods:

Structured PMMA fibers were fabricated via dry-wet spinning. The adsorption performance of optimized fibers was evaluated with serum containing β₂-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 β₂-MG adsorption. Cross-shaped fibers exhibited the highest blood-contact surface area and adsorption capacity. A thin surface-dense layer (<0.1 μm) improved β₂-MG diffusion while limiting albumin uptake. TOF-SIMS confirmed uniform β₂-MG penetration, with albumin confined near the fiber surface. Adsorption exceeded 50% for mid-weight proteins (~52 kDa), including IL-6, α₁-microglobulin (α₁-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 β₂-MG removal and favorable flow dynamics for hemoperfusion therapies targeting mid-weight uremic toxins.