There is considerable interest in dexamethasone, a synthetic glucocorticosteroid drug, and a number of reports detailing the controlled release of dexamethasone from polypyrrole have been published. However, polypyrroledoped with dexamethasone is poorly characterised. In this study, polypyrrole doped with dexamethasone was formed at relatively low applied potentials of 0.70 V or 0.80 V vs SCE by carrying out the electropolymerisation on an initial pre-layer of polypyrrole. These polymers displayed electroactive behaviour with a dexamethasone doping level of 0.30 ± 0.03 and using impedance measurements the charge-transfer resistance was computed as 400 Ω. Mixed ion transport was observed. In addition to the release of dexamethasone, hydrated sodium cations were incorporated to maintain charge neutrality on reduction of the polymer. Approximately 200 μg cm −2 of dexamethasone was released following 60 min on reduction of the polymer at −0.90 V vs SCE. It was possible to re-use the polymer to release the drug by repeated oxidation and reduction steps, where dexamethasone was incorporated during oxidation and released on reduction. During these events, sodium was accumulated within the polymer matrix and this high salt content accompanied with swelling and de-swelling events gave rise to the development of cracks in the polymer matrix.

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We have assessed the utility of morphological and microsatellite markers for tracing field hybridization between Lolium multiflorum and Lolium perenne in cereal-enclosed gene flow plots. The presence of awns on the inflorescence of F 1 hybrids was found to be a reliable, but underscoring, indicator of L. multiflorum paternity in L. perenne derived seed as determined by inheritance of species-specific alleles at the microsatellite locus 'H01 H06' in these progeny. A positive correlation was evident in the experimental treatment between the number of pollen donor plants in a given plot and the frequency of hybrid F 1 seed harvested from pollen receptor plants in that plot. These experiments have established the utility of naturally occurring heritable markers for the measurement of gene flow rates in field Ryegrass populations, with particular significance for risk assessment modeling of potential gene flow from transgenic grass cultivars.

a b s t r a c tIn this paper, attempts to dope polypyrrole (PPy) with two small sized anionic drugs, diclofenac sodium salt (NaDF) and valproic acid sodium salt (NaVPA), are described. For PPy doped with DF − , unusual patterns in growth and morphology were observed. During the deposition of the polymer, the rate of electropolymerisation decreased with increasing time and higher applied potentials. The polymer had features of an insulating film, while SEM confirmed the presence of crystal-like shards on the surface of the polymer. Analyses of these crystals indicate them to be drug that may have precipitated out of solution. These findings suggest that insoluble drug crystals are formed during electropolymerisation. The formation of PPy doped with a small soluble anti-epilepsy anionic drug, VPA − , was also studied; however it was not possible to incorporate this drug during electrochemical polymerisation. Again, this was explained in terms of the equilibrium between the anion and the acid forms of VPA. At pH values below 5.6, the equilibrium of the VPA − is shifted towards the insoluble HVPA. As the monomer is oxidised, there is a decrease in the local pH in the vicinity of the electrode and this causes the HVPA to precipitate from solution. This, in turn, prevents any PPy from being deposited at the electrode.