Novel thin-film nanofibrous composite membranes containing directional toxin transport nanochannels for efficient and safe hemodialysis application

Polymeric hemodialysis (HD) membranes with limited porosities, tortuous pores, and broad pore size distributions suffer from a trade-off between permeability-i.e., how fast toxins pass through the membranes- and selectivity-i.e., to what extent necessary proteins are retained. Here, a novel thin-film nanofibrous composite (TFNC) membrane, composed of an electrospun polyacrylonitrile (PAN) nanofibrous support layer and a chemically cross-linked polyvinyl alcohol (PVA) separation layer filled with heparin functionalized multi-walled carbon nanotubes (Hep-g-pMWCNTs), was demonstrated for efficient and safe HD application. Combining dialysis simulation experiments and pore-flow model, we demonstrated that the formation of free nanogaps at the interface between Hep-g-pMWCNTs and PVA matrix provided additional directional nanochannels for toxins to transport. The membranes showed efficient toxins removal without sacrificing selectivity (with the urea clearance of 88.2%, lysozyme clearance of 58.6%, and bovine serum albumin retention of 98.4% in a 4 h simulating dialysis). Especially, the efficiency in removing middle molecule toxins increased obviously compared with the values reported to date. Besides, the membranes exhibited excellent hemocompatibility: high resistance to protein adsorption, suppressed platelet adhesion, favorable anticoagulant activity, limited hemolysis ratio, and low complement activation. These facts suggested that the Hep-g-pMWCNTs/PVA/PAN TFNC membranes with superior comprehensive performances presented great potential for HD application.