Making positively charged polymer biocompatible

Yadong Wang, University of Pittsburgh, DMR 1005766

Self assembly between cations (positively charged ions) and anions (negarively charged ions) is ubiquitous throughout nature. Important biological structures such as chromatin (DNA assembly) are assembled by a poly-cation and a poly-aninon. Biomedical importance of synthetic polycations arises from their affinity to polyanions such as DNA. However, the toxicity of synthetic poly-cations hampers the realization of their immense potential. We reason that to make a poly-cation biocompatible, our body has to be able to break it down and it should be made from parts naturally found in our body. This design philosophy guided us to a biocompatible poly-cation based on arginine (a positively charged natural amino acid). The poly-cation is orders of magnitude more compatible than conventional polycations. This biocompatibility diminishes when L-arginine is substituted with the un-natural D-arginine or when cells can’t break down the polymer. This design can lead to many biocompatible polycations that will significantly advance a wide range of applications including controlled release, tissue engineering, biosensing, and medical devices.

* BJ Zern, H Chu, AO Osunkoya, J Gao, and Y Wang: A Biocompatible Arginine-based Polycation , in press at Advanced Functional Materials

• Current applications of poly-cations

are limited by their low

biocompatibility.

• Our work on philosophy of

polycation design would lead to

next generations of biocompatible

poly-cations.

• The hugely improved

biocompatibility will enable

translation of polycation research in

delivery of biological therapeutics,

tissue engineering, biosensors, and

many other fields.

• AO Osunkoya is an African

American collaborator.

Making positively charged polymer biocompatible

Yadong Wang, University of Pittsburgh, DMR 1005766

The polymer will be compatible with our body even when highly positively charged if 1: our body can break it down and 2: the polymer is made from parts naturally found in our body.The top panel is a polymer made following this design philosophy. The green cells are alive, very few dead cells (red) are visible. Bottom panel: deviation from either rules, the polymer is toxic. Far more dead (red) cells than alive (green). This is validated in animals.