INCORPORATION OF SULFONATED CYCLODEXTRINS INTO POLYPYRROLE - AN APPROACH FOR THE ELECTRO-CONTROLLED DELIVERING OF NEUTRAL-DRUGS

The electro-controlled delivery of drugs based on the doping-dedoping mechanism of Electro-Conducting Polymers is restricted to charged subs tances acting as dopants. In order to overcome this limitation, this s tudy presents an approach where the trapping/delivering is based on ho st-guest interaction. As an example of a neutral guest, the molecule N -methylphenothiazine (NMP) is encapsulated in the host, heptasulphonat ed beta-cyclodextrin (beta-CDSO3-), which is tailor-made to dope PPy. The original synthetic method for beta-CDSO3- is based on sulphonation of the periodated beta-CD in the phase transfer medium. As a conseque nce of their size and of their multicharged character, beta-CDSO(3)(-) s are fixed dopants. The stability of the beta-CDSO3- entrapment is ch ecked by Optical Beam Deflection (mirage effect) measurements. The ion ic movements associated with the switching of the beta-CDSO3- doped PP y (PPy(+), beta-CDSO3-) film appear to be mainly due to cations with t his technique. Cyclic voltammetry experiments confirm the entrapment o f neutral NMP by simply dipping the PPy(+), beta-CDSO3- film in a CH3C N solution containing NMP. Repeated electrochemical cycling of such a reservoir electrode indicates the progressive elimination of NMP from the (PPy(+), beta-CDSO3- [NMP]) film.