An electrochemical, in vitro bioactivity, and quantum chemical approach to nanostructured copolymer coatings for orthopedic applications A. Madhankumar • Suresh Ramakrishna • P. Sudhagar • Hyongbum Kim • Yong Soo Kang • I. B. Obot • Zuhair Mattoug Asad Gasem Received: 22 December 2013 / Accepted: 29 January 2014 / Published online: 28 February 2014 Ó Springer Science+Business Media New York 2014 Abstract Conducting polymers represent a promising platform toward coating materials for implant technologies in recent years. In this investigation, copolymers based on pyr- role (Py) and 3,4-ethylenedioxythiophene (EDOT) were electrodeposited on 316L SS with various feed ratio of Py/ EDOT through cyclic voltammetric technique. The surface and chemical structure of the synthesized copolymers were analyzed by SEM, AFM, FT-IR, and 1 H NMR spectroscopic analysis. The influence of comonomer feed ratio on electro- chemical corrosion behavior was investigated in stimulated body fluid. A significant lower corrosion current with nobler shift in corrosion potential and higher charge transfer resis- tance values of copolymer-coated 316L SS were obtained and the comparisons were made with uncoated as well as their homo polymers. Furthermore, in vitro cell culture studies were performed on MG63 osteoblast human cells to confirm the biocompatibility of copolymer coatings. Quantum chemical approach was employed to verify the obtained experimental outcomes. As a result of this investigation, it was concluded that the performance of coatings was strongly dependent to the monomer feed ratio and the copolymer synthesized with 50:50 feed ratio showed high corrosion protection efficiency with improved cell growth on MG63 osteoblast cell. Introduction Conducting polymers (CPs) have recently attracted consid- erable scientific and technological interest in consequence of their potential applications in secondary batteries, biosen- sors, solar cells, supercapacitors, and protection against corrosion [1–3]. CPs provide a unique combination of elec- trical conductivity as metals with processability as polymers. Many researchers have extensively studied to use CPs, such as polyaniline (PANI), polypyrrole (PPy), polythiophene (PTh), and their derivatives for corrosion protection of metals [4]. Among them, PANI family stands out for their excellent stability, higher corrosion inhibition owing to their different oxidations states as well as relatively low cost. Regrettably, the application of PANI coatings has been limited due to possible presence of benzidine moieties in the polymer backbone, which might yield toxic (carcinogenic) products upon degradation [5]. In contrast, the PPy and PTh family are probably more environmentally ‘‘friendly’’ materials and attracted considerable attention in biomedical applications in the last decade. Biocompatibility of some CPs has been recently veri- fied, opening a new field of research focused on the use of these polymers as coating materials for biomedical appli- cations. Polypyrrole (PPy) has recently utilized as bio- compatible coatings for implants and its biocompatibility has been well documented due to their nobler properties including good specific conductivity, chemical stability, ease polymerizability and compatibility with mammalian A. Madhankumar (&) Á I. B. Obot Á Z. M. A. Gasem Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran 31261, Kingdom of Saudi Arabia e-mail: madhankumar@kfupm.edu.sa S. Ramakrishna Á H. Kim Graduate School of Biomedical Science and Engineering/ College of Medicine, Hanyang University, Sungdong-gu, Seoul, South Korea P. Sudhagar Á Y. S. Kang Energy Materials Laboratory, WCU Program Department of Energy Engineering, Hanyang University, Seoul 133-791, South Korea 123 J Mater Sci (2014) 49:4067–4080 DOI 10.1007/s10853-014-8094-6