Polyaniline-poly(styrene sulfonate) conducting hydrogels reinforced by supramolecular nanofibers and used as drug carriers with electric-driven release

Due to the very poor mechanical strength of polyaniline-poly(styrene sulfonate) (PANI-PSS) conducting hydrogels, we explored the possibility to improve the strength of PANI-PSS hydrogels using supramolecular nanofibers formed by self-assembly of sorbitol derivatives (DBS). The compressive strength of these reinforced hydrogels was found to be 11 times higher than that of the unreinforced one. SEM studies indicated that the in-situ formed DBS nanofibers and PANI-PSS chains are entangled, leading to improvement of the hydrogel strength. The conductivity of reinforced hydrogels measured by impedance was found to be 10(-4) S/cm, rather similar to that of the unreinforced hydrogels. In addition, the spectra of cyclic voltammetry for the reinforced and unreinforced hydrogels were almost the same. These results reveal that the presence of DBS nanofibers does not affect the electric properties of PANI-PSS hydrogels. As drug carriers with electric-driven release, the release rate of model drug Rhodamine B loaded within reinforced PANI-PSS hydrogels distinctly increased when an increase of voltage was applied. Furthermore, a pulse release could be realized when the voltage was alternatively applied. (C) 2015 Elsevier Ltd. All rights reserved.