Development of Electroactive Tetra(aniline) Based Potential Biomaterials

Abstract

The electroactive tetra(aniline) TANI is an oligomer of poly(aniline) possessing intrinsic antioxidant properties. Two types of TANI-based materials were synthesized by solution polycondensation method. In the first part of the studies, a varying concentration of the synthesized TANI was incorporated as an electroactive segment in the terpolymers along with PEG6k and fumaric moieties. The synthesized material was structurally characterized by FTIR, 1H and 13C NMR spectroscopic studies and molecular weight was determined by the GPC technique. The electroactivity of the synthesized terpolymers was elucidated using UV-Vis-NIR spectroscopic and cyclic voltammetric techniques. The thermal properties of the synthesized terpolymers related to the content of TANI were explored by employing TGA and DSC analyses. WAXD analysis was performed to check the effect of TANI on the crystallinity of terpolymers. Due to hydrophobic and rigid behavior of TANI whereas hydrophilic and flexible behavior of PEG, the synthesized terpolymers were expected to self-assemble in aqueous medium. Hence the aqueous self-assembly of the synthesized terpolymers was investigated using SEM and DLS studies showing the aggregation behavior of the material. The antioxidant activity of the synthesized materials was determined using stable free radical (DPPH) assay. Furthermore, the therapeutic potential of the synthesized terpolymers having intrinsic antioxidative nature was explored in an oxidatively stressed diabetic animal model (SD rats). These terpolymers were also studied for their cytotoxicity, hydrolytic biodegradation, and effect of their antioxidant properties on multiple organ systems affected by oxidative stress. In the second part of the study, TANI was used as a hydrophobic segment along with mPEG as a hydrophilic segment in the synthesis of amphiphilic ABA (mPEG-TANImPEG) type triblock copolymers. The synthesized material was structurally elucidated by FTIR, 1H and 13C NMR spectroscopic techniques and molecular weight was estimated by using mass spectrometric (MALDI-TOF MS) analysis. The electrochemical properties of the synthesized triblock copolymers were studied by using UV-Vis-NIR spectroscopic and cyclic voltammetric studies. The synthesized amphiphilic triblock copolymers were investigated for their aqueous self-assembly. The critical micelle concentration (CMC) of the synthesized aggregates was determined by utilizing the Fluorescence probe experiment using pyrene as a hydrophobic probe. The CMC of the materials was tuned based on the oxidation state of the TANI segment embedded in triblock copolymers. The effect of pH, oxidation state and molecular weight on the aggregation behavior of triblock copolymers was also studied. The synthesized triblock copolymers possess the good antioxidant property that was investigated by a stable free radical DPPH assay. The biological evaluation of the synthesized material as a potential biomaterial was carried out based on their electroactive and antioxidant behavior. The biological studies were comprised of cytotoxic analysis (hemolytic assay), DNA interactions (binding and damaging assay), and antibacterial activity.