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Chronic kidney disease, a growing public health concern affecting 11-13% of the global population is defined by an irreversible worsening of renal function which can lead to end stage renal disease (ESRD) [1]. Hemodialysis (HD) is the most widely used renal replacement therapy to purify the blood of ESRD patients and the majority of hemodialyzers on the market are composed of synthetic polymer membranes with large pore sizes that allow the removal of uremic toxins (UTs) of large molecular weight. Nevertheless, studies focused on the ultrafiltrate removed from ESRD patients identified the convective removal of useful and even vital compounds found in blood [2]. In this study, a novel cellulose acetate-based monophasic hybrid skinned amine-functionalized CA-SiO$_2$-(CH$_2$)$_3$NH$_2$ membrane was synthesized by an innovative method which combines the phase inversion and sol-gel techniques [3,4]. The morphological characterization of the hybrid membrane was performed by scanning electron microscopy (SEM) and the chemical composition was analyzed by Fourier transform infrared spectroscopy in attenuated total reflection mode (ATR-FTIR). Characterization of the monophasic hybrid CA-SiO$_2$-(CH$_2$)$_3$NH$_2$ membrane in terms of permeation properties was carried out in an in-house built single hemodialysis membrane module (SHDMM) under dynamic conditions. Permeation experiments were performed to determine the hydraulic permeability (Lp) and rejection coefficients to reference solutes pertaining to the metabolic functions of the kidney and determination of the molecular weight cut-off (MWCO). For comparison purposes, a pure cellulose acetate (CA) membrane was also synthesized and characterized. SEM confirmed asymmetric membrane cross-section structures and ATR-FTIR confirmed the covalent bonding between CA and SiO2. The permeation studies revealed for the novel anime-functionalized membrane an increase in the hydraulic permeability by an approximate factor of 2 when compared to the pure CA membrane. The two membranes under study showed to be fully permeable to small water-soluble uremic toxins, while retaining BSA. CA-SiO$_2$-(CH$_2$)$_3$NH$_2$ and pure CA membranes yielded an estimated MWCO of 24.5 kDa and 18.1 kDa, respectively.
