Elisa Pedone

An information rich biomedical polymer library

We have designed and prepared a library of polymers with the aim to use a minimum number of polymers to obtain relevant information about structure–property correlations. An active ester homopolymer precursor and two blocked copolymer active ester precursor polymers were used to prepare a library of 16 cationic functionalised polymethacrylamides. These precursor polymers are narrow molecular weight distribution (MWD) polymers prepared by copper mediated polymerisation. This allows a precursor polymer to be used to generate a family of functionalised polymers for study, all with the same molecular weight characteristics. The polycations were then prepared by the sequential conjugation of two amines from the following set: (2-aminoethyl)trimethylammonium chloride hydrochloride (TMA), 3-(dimethylamino)propylamine (DMA), histamine (His) and 1-amino-2-propanol (AP). The conjugates contained different amounts of tertiary amine, quaternary ammonium, imidazole and hydroxypropyl pendent moieties that were selected to provide differing degrees of charge density along the polymer main chain. The molecular weight characteristics, viscosities and aqueous solubility of the polycations were evaluated at pH 4 and 7 to determine property trends. These conjugates were assessed for their ability to complex plasmid DNA at pH 7.4 and 4.5 by agarose gel electrophoresis. Triple detection GPC analysis at different pH values relevant to the cellular environment and photon correlation spectroscopy results indicated that some polycations formed interpolyelectrolyte complexes of under 100 nm. Preliminary titration and cellular biocompatibility studies are also described.

Diethylstilbestrol glutamate as a potential substrate for ADEPT.

The combination of systemic toxicity, water insolubility and a labile chemical structure has limited the clinical use of diethylstilbestrol (DES) 1 for the treatment of prostate cancer. To determine if DES could potentially be a prodrug substrate for the pre-targeting strategy known as antibody directed enzyme prodrug therapy (ADEPT), the DES-glutamate 5 was prepared. The synthesis required the activation of the bis-t-butyl glutamate ester 2 to the isocyanate 3 followed by addition of DES 1. The desired DES-glutamate 5 was water-soluble and upon incubation with carboxypeptidase G2 (CPG2) underwent carbamate cleavage to give DES 1. A control reaction in the absence of CPG2 demonstrated that the enzyme was necessary for rapid glutamate cleavage to give DES 1. HPLC analysis was required to follow the reaction of DES-glutamate 5 with CPG2. These preliminary results suggest that it may be possible to examine an ADEPT strategy for DES provided enzymatic kinetics can be measured.