Electroactive PEDOT:PSS/HNTs Nanocomposites for Biological Application

One of the main challenges in smart biointerfaces concerns the development of materials able to respond to external stimuli and to show compatibility with biological environment. In the last decades, conductive polymers (CPs), have been widely studied and developed as electroactive materials for application in the neural fields. Poly(3,4-ethylenedioxythiophene):Polystyrene Sulfonate (PEDOT:PSS), an intrinsically conductive polymer, is nowadays widely used for its electrical, electrochemical, optical, and mechanical properties that make it an excellent choice for biointerfaces and bioelectronics due to its biocompatibility. Physico-chemical properties of this polymer can be improved through the formation of composites, in this work we used Halloysite Nanotubes (HNTs), an aluminosilicate clay mineral with an empty lumen, which modification increases the application field.<br/>Herein, it is investigated the use of HNTs as filler to obtain PEDOT:PSS/HNTs nanocomposites. Two different HNTs based fillers were used: i) pristine HNTs and ii) HNTs loaded with PEDOT:PSS.<br/>Physico-chemical properties of the thin films of PEDOT:PSS and HNTs nanocomposites were studied by mean of Atomic Force Microscopy (AFM) for morphological analysis, Force Spectroscopy to investigate the nanomechanical properties, Electric Current Spectroscopy to extract the local I-V characteristics in air, Cyclic Voltammetry (CV) for the capacitance of the films in water medium and Ellipsometric Spectroscopy (ES) to evaluate the films’ thickness and optical properties.<br/>Our study shows a very surprising results, despite HNTs are insulators, their presence in the PEDOT:PSS matrix enhance the electrical and electrochemical properties of PEDOT:PSS itself, and improve the stiffness of the material, making the proposed composite a better candidate for biological applications, for example, it could be used as stiffer materials for controlled drug release devices or manufacturing of prosthetics and medical devices.<br/>Also, results show that physico-chemical properties of PEDOT:PSS/HNTs composite films depends on PEDOT:PSS loading all over the HNTs structure.