Clevertex - Grado Zero Espace Srl

separation capacity, ion-exchange fibres present more attractiveness for use than other ion-exchange
materials.
Ion-exchange fibres have either a positive or a negative electric charge, which is compensated by
mobile counter-ions of opposite charge. The principle of ion-exchange is based on electroneutral
condition. Ion-exchange generally is a diffusion process, sensible to concentration gradients. Many
drugs are charged at physiological pH, therefore they can act as mobile counter-ion, and this allows
them to be used as drug delivery systems.
An example of an already commercialised ion-exchange fibre suitable for drug delivery is given by
Smopex ® fibres from SmopTech Co. in Turku/Finland.
Another possibility to obtain ion-exchange fibres is to graft ion-exchange groups to cotton, flax,
cellulose, wool, polyethylene, polystyrene, polyacrylonitrile, polyamide and carbon fibres. In- and exvivo
ion-exchange drug delivery systems have been developed. In-vivo the drugs can be released by
ions present in body fluids, whereas in ex-vivo applications the concentration of ions needed for the
exchange is determined by excretion through the skin. A research team in Finland at the Helsinki
University of Technology is working on ion-exchange fibres in transdermal iontophoresis. The aim of
the study is to develop a controlled drug delivery vehicle for trans-dermal iontophoresis using fibrous
ion-exchangers as a drug reservoir. For this purpose, positively charged model drugs; tacrine,
metoprolol (figure below), nadolol and propranalol are loaded into the ion-exchange groups of the fibre
and then released using a salt solution, containing counter-ion to the drug, and weak current,
iontophoresis [197].
N
NH2
Tacrine Metoprolol
Fig. 112 ........Chemical structures of Tacrine and Metoprolol
Researchers from the University of Belgrade developed cation-exchange fibres based on PAN with
the carboxylic group as functional group.
Further, the Thüringisches Institut für Textil- und Kunststoff-Forschung e.V. (TITK) is researching on
ion-exchange fibres on cellulosic basis. They developed a special process, the ALCERU ® technology,
to dissolve cellulose directly without any chemical modification for producing textile fibres in a
subsequent spinning process. The possible homogeneous integration of organic or inorganic additives
NH
OH
O
O
125