Reaction of poly(acrylamide-co-vinylamine) with tresyl-PEG in the presence of PC12 cells

Tresylation of an amine containing polymer film in the presence of PC12 cells did not result in a significant loss of cell viability, at least as assessed by trypan blue exclusion or MTT assay. PC12 cells were cultured atop reactive poly(acrylamide-co-vinyl amine) films or tissue culture polystyrene and exposed for 2 h to tresylated polyethylene glycol (TPEG) or unreactive hydrolyzed TPEG in 0.1 TES (N-tris hydroxymethyl-2-aminoethane sulfonic acid). The loss in trypan blue viability was limited ( 80% retained), provided the TPEG concentration was 10 μmol/g or less. Similarly when microencapsulated PC12 cells (in a non-reactive polyacrylate hydrogel) were exposed to TPEG (10 μmol/g in 0.1 TES) the loss of MTT activity was small. The loss of vaibility was attributed to the toxicity of the tresyl leaving group and not the reaction itself. Thus, it may be possible to surface modify cell containing microcapsules, at least under limited conditions, in order to improve their biocompatibility without compromising the viability of the enclosed cells. This should lead to the development of new (reactive) polymers for microencapsulation since biocompatibility need not be a design consideration in the first instance.