Fig. 3From: Recent trends in therapeutic application of engineered blood purification materials for kidney diseasea Schematic illustration of the preparation of NPCA beads. b Illustration of the removal mechanism of PBUTs by using NPCA. The symbol ’N’ in the scheme represents the richest type of N atoms, which are assigned to be pyridinic N, pyridonic/pyrrolic N and quaternary N in NPCA. Reproduced with permission [31]. Copyright 2021, ElsevierBack to article page