Investigation of salt effects on poly (sulfonic diphneyl aniline)

The polymers bearing both positive and negative charges, i.e. polyzwitterions, were investigated in order to use of drug delivery and especially gen transfer. It seems possible that these polymers can bind to the gen by means of their charges and they can release the gen after transportation if provided the required conditions such as, pH, salt concentration, etc. However, the aggregates of the aliphatic polyzwitterions are not so much stable and then decompose during transportation. Poly (sulfonic diphenyl aniline) (PSDA) is a water soluble and more stable aromatic polyzwitterion since it bears both positive and negative charges. Therefore, it bears the potential for the the use in controlled delivery of a gene or drug. In order to investigate the suitability of PSDA for this field, the zeta potential, hydrodynamic radius and ionic conductivity of the PSDA aggregates in aqueous solutions were measured as a function of pH, type of salt and salt concentration. SEM/STEM pictures of some samples were taken. It was found that PSDA can give some pH sensitive aggregates of which size and shape can change by salt type and concentration at very low pH values. It was concluded that PSDA can be used in drug and gen delivery systems and in preparing pH sensitive materials at very strong acidic media.