Electroconductive and injectable hydrogels based on gelatin and PEDOT:PSS for a minimally invasive approach in nervous tissue regeneration

This work describes the development of electroconductive hydrogels as injectable matrices for neural tissue regeneration by exploiting a biocompatible conductive polymer – poly(3,4-ethylenedioxythio- phene)-poly(styrenesulfonate) (PEDOT:PSS) – combined with a biomimetic polymer network made of gelatin. Our approach involved also genipin – a natural cross-linking agent – to promote gelation of gelatin networks embedding PEDOT:PSS. The achieved results suggest that physical–chemical properties of the resulting hydrogels, like impedance, gelation time, mechanical properties, swelling and degradation in physiological conditions, can be finely tuned by the amount of PEDOT:PSS and genipin used in the for- mulation. Furthermore, the presence of PEDOT:PSS (i) enhances the electrical conductivity, (ii) improves the shear modulus of the resulting hydrogels though (iii) partially impairing their resistance to shear defor- mation, (iv) reduces gelation time and (v) reduces their swelling ability in physiological medium. Additionally, the resulting electroconductive hydrogels demonstrate enhanced adhesion and growth of primary rat cortical astrocytes. Given the permissive interaction of hydrogels with primary astrocytes, the presented biomimetic, electroconductive and injectable hydrogels display potential applications as mini- mally invasive systems for neurological therapies and damaged brain tissue repair.