Functionalized nanoparticles for endotoxin binding in aqueous solutions

Nanoparticles consisting of a polystyrene core and a polyglycidyl methacryl ate shell were prepared by a two-step emulsion polymerization. The size and surface properties of the particles were characterized by scanning electro n microscopy, dynamic light scattering and polyelectrolyte titration techni ques. Particles were found to be monodisperse with a mean diameter of about 85 nm. Parent particles were modified with a number of different ligands i ncluding diamines of increasing chain length, amino acids and corresponding amines and higher molecular weight ligands like polymyxin B. The modified particles were tested for their endotoxin (ET) binding capacity in water an d physiological sodium chloride solution with the Limulus amebocyte lysate (LAL) assay. It was found that the ET binding properties of the different l igands depend both on the ability of the ligand to form Coulomb- and van de r Waals-interactions with the ET molecule influenced by the nature of the s uspension medium. Therefore, the choice of ligands for particle modificatio n has to consider minutely the conditions under which ET has to be removed, e.g. removal from pure water, dialysis fluids, plasma or blood. (C) 1999 E lsevier Science Ltd. All rights reserved.