A Ninhydrin-Type Urea Sorbent for the Development of a Wearable Artificial Kidney

The aim of this study is to develop polymeric chemisorbents with a high density of ninhydrin groups, able to covalently bind urea under physiological conditions and thus potentially suitable for use in a wearable artificial kidney. Macroporous beads are prepared by suspension polymerization of 5-vinyl-1-indanone (vinylindanone) using a 90:10 (v/v) mixture of toluene and nitrobenzene as a porogen. The indanone groups are subsequently oxidized in a one-step procedure into ninhydrin groups. Their urea absorption kinetics are evaluated under both static and dynamic conditions at 37 degrees C in simulated dialysate (urea in phosphate buffered saline). Under static conditions and at a 1:1 molar ratio of ninhydrin: urea the sorbent beads remove approximate to 0.6-0.7 mmol g(-1) and under dynamic conditions and at a 2:1 molar excess of ninhydrin approximate to 0.6 mmol urea g(-1) sorbent in 8 h at 37 degrees C, which is a step toward a wearable artificial kidney.